Paper 1
The synthesis, characterisation and isolation of tetranuclear manganese carboxylate complexes with HQ, derivatives such as 5-chloro-8-hydroxyquinoline (Cl-HQ) and 2-(hydroxymethyl) pyridine (hmpH) have been reported by Christuo (1992).
Reaction mixtures containing Mn(O2CR)2, HO2CR (R = Me, Ph), NR’4MnO4 (R’ = Me, Et, Bu”), and L-L (L-L = HQ, Cl-HQ and hmp) in MeCN give red-brown solutions from which the products (NR’4)[Mn4O2(O2CMe)7(HQ)2] (R’= Bu”, Et, Me), (NMe4)[Mn4O2(O2CPh)7(HQ)2], (NMe4)[Mn4O2(O2CMe)7(Cl-HQ)2] and (NR’4)[Mn4O2(O2- CPh)7(hmp)2] (R’ = Me, Et, Bun). Single crystals were obtained from a solution of (NR’4)[Mn4O2(O2CMe)7(HQ)2] (R’= Bu”) and from a solution of (NR’4)[Mn4O2(O2- CPh)7(hmp)2] (R’ = Me). The complexes crystallise in orthorhombic space group P212121 and triclinic space group P1-.
The structures of the anions in the two compounds are very similar. The anion in both complexes possesses a Mn4O2 core in which each oxygen atom is bridging to three manganese ions. The seven carboxylate ligands each bridge between two manganese ions. The “body”-Mn to μ3-O distances are in the range of 1.875–1.907 Å (average 1.892 Å), whereas the “wingtip”-Mn to μ3-O distances are very slightly shorter (1.857–1.882 Å) (average 1.868 Å). The Mn–O–Mn angles (95.7(3)–97.3 (3)°). The central Mn…Mn distance is the shortest 2.82 Å, whereas the outer Mn…Mn distances are in the range 3.3–3.4 Å. The coordination number of each manganese ion is 6.
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Paper 2
Justyniak (2014) Synthesis an Arylmanganese(II) 8-Hydroxyquinolinate Tetranuclear Cluster. Reaction of 8-hydroxyquinoline with dimesitylmanganese [(Mes)2Mn]3 in toluene, crystallization from THF/toluene mixture at –25 °C for one week gave The dark red crystals of arylomanganese(II) tetranuclear cluster [(Mes)2Mn4(Q)6]·4PhMe were air-sensitive and changed into black in 10 min when exposed to air.
The complex crystallise in triclinic space group P1 ̄. Molecular studies showed that the centrosymmetric molecule contains two pairs of manganese atoms of different coordination modes formed by association of the two dinuclear [MesMn(Q)][Mn(Q)2] moieties. The symmetric [MesMn(Q)][Mn(Q)2] unit consists of one five-coordinate and one six-coordinate manganese(II) atom. The coordination sphere of the five-coordinate Mn(II) atom is completed by one terminally bound mesityl group, one chelated quinolin-8-olate anion, and the two μ2-O atoms of two other quinolin-8-olate anions, which themselves engage in chelation to the other Mn(II) atoms. The symmetric [MesMn(Q)][Mn(Q)2] unit consists of one five-coordinate and one six-coordinate manganese(II) atom. The coordination sphere of the five-coordinate Mn(II) atom is completed by one terminally bound mesityl group, one chelated quinolin-8-olate anion, and the two μ2-O atoms of two other quinolin-8-olate anions, which themselves engage in chelation to the other Mn(II) atoms. The six-coordinate Mn atom linked to two μ3-O atoms of the anions that chelate the mesityl-bound metal atom, and is chelated by two quinolin-8-olate ligands. This metal atom adopts a distorted octahedral coordination environment with essentially equal Mn–O and Mn–N bond lengths (average: 2.190 Å).
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Paper 3
Meanwhile, a family of asymmetric trinuclear chromium-oxo complexes including [Cr3O(O2CPh)4(HQ)3], [Cr3O(O2CPh)4(5-Cl-8-HQ)3] and [Cr3O(OAc)4(8-HQ)3] were described by Vincent (1995). One example, [Cr3(O2CPh)4(HQ)3] crystallizes in the triclinic space group P1-. The [Cr3O]7+ core of the complex is distinctly unsymmetric with Cr…Cr separations of 2.909(1), 3.235(1), and 3.466(2) Å. The Cr—O—Cr angles of 94.4(2), 118.1(2), and 130.2(2)°. The general feature of the magnetic data for [Cr3O(O2CPh)4(HQ)3] and [Cr3O(OAc)4(8-hqn)3] complexes is approximate for a timer with antiferromagnetic exchange within the chromium (III) trimeric unit.
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Paper 4
Dinuclear Sc2Q6 with the 8-quinolinolate ligands were prepared by Katkova (2011). Two scandium atoms are inequivalent due to different ligand surroundings. The complex crystallizes in the monoclinic space group P21/c. The Sc…Sc distance is 3.262 Å where three quinolinolate ligands are bridging and three ligands are terminal. The first Sc cation is coordinated by one terminal and three bridging ligands whereas the second Sc cation is coordinated by two terminal and three bridged ligands. Only oxygen atoms in these ligands are µ2- bridging. The terminal Sc–O distances are significantly shorter than the bridging Sc–O distances. The Sc–O and Sc–N bond lengths are in the range of 2.037(1)–2.276(1)Å and 2.315(2)–2.600(2)Å respectively.
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Paper 5
Tanaka (1983) presented the first single-crystal X-ray diffraction study on a μ-oxo dimeric vanadium [VO(C9H6NO)2]2O. The complex crystallise in monoclinic space group C2/c. The distorted octahedral six-coordination around the vanadium atom in a VO2Q2 unit is completed by the terminal oxygen atom, the oxygen atom bridging two vanadium atoms, and the two nitrogen and the two oxygen atoms of Q ligands. The V–O–V angle is 173.4(4)°. The V–O bond lengths are in the range of 1.587(6)–1.925(6)Å. The V–N bond lengths are 2.199(7) and 2.310(6)Å. The O–V–O angles are in the range of 90.8(2)–157.2(3)°.
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Paper 6
Shibahara and et al (2009), prepared many 8-quinolinolato vanadium (IV) complexes. Reaction of vanadium (III) chloride with 8-quinolinol (HQ) gave three dinuclear vanadium (IV) complexes: [V2O2Cl2(Q)2(H2O)2].HQ, and [V2O2Cl2(Q)2(X)2] where X = (C3H7OH) or (C4H9OH). Reaction of vanadium (III) chloride with 5-chloro-8-quinolinol (HClQ) gave four dinuclear vanadium (IV) complexes: [V2O2Cl2(ClQ)2(H2O)2].2HClQ, [V2O2Cl2(ClQ)2(X)2] .n C4H9OH where X = (C3H7OH), (C6H5CH2OH) and (C4H9OH). Reaction of vanadium (III) chloride with 5-fluoro-8-quinolinol (HFQ) gave two dinuclear vanadium (IV) complexes: [V2O2Cl2(FQ)2(H2O)2]. HFQ. 2H2O and [V2O2Cl2(FQ)2(C3H7OH)2]. The X-ray structures of all complexes (except [V2O2Cl2(Q)2(H2O)2].HQ, [V2O2Cl2(ClQ)2(H2O)2].2HClQ, and [V2O2Cl2(FQ)2(H2O)2]. HFQ. 2H2O) have been determined with variable space group. All the dinuclear complexes reported here have (V–O)2 rings. The V…V separation are in the range of 3.338(2) –3.3860(2)Å. The V–O–V angles are in the range of 106.57(4)–108.25(3)°. The V–O, V–N and V–Cl bond lengths are in the range of 1.9855(3)–2.13(2)Å, 2.09(1)–2.112(1)Å and 2.3677(5)–2.3761(5)Å respectively.
Magnetic measurements of [V2O2Cl2(Q)2(X)2] where X = (C3H7OH) or (C4H9OH), [V2O2Cl2(ClQ)2(X)2] where X = (C3H7OH) or (C6H5CH2OH) and [V2O2Cl2(FQ)2(C3H7OH)2] in solid state show very weak antiferromagnetic behaviour.
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Paper 7
Cheng (2002) prepared complexes of titanium (IV) and 8-hydroxyquinoline. Reaction Ti(OPri )4 and 8-hydroxyquinoline (HQ) resulted in [TiQ2(OPri )2]. To dried dichloromethane solution containing [TiQ2(OPri )2], five drops of deionized water were added. After standing for 3 days, orange crystals [TiQ2(µ-O)]4 .nH2O were obtained. The complex crystallise in tetragonal space group P21c4-. The skeleton of the tetramer is a [TiQ2(µ-O)]4 eight-membered ring. Each Ti atom is coordinated to two 8-hydroxyquinlinate ligands via both the nitrogen atoms and oxygen atoms. In addition, two bridging oxo ligands also coordinated to each Ti atom completing the distorted octahedral environment of each Ti atom. The Ti–O and Ti–N bond lengths are in the range of 1.79(1)–1.97(1)Å and 2.26(1), 2.29(1)Å respectively. The O–Ti–O, O–Ti–N and N–Ti–N are in the range of 92.5(5)–153.0(5)°, 74.7(5)–164.5(5)° and 83.1(5)° respectively.
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Paper 8
Weng Ng (2004) prepared Di-µ-ethoxy-bis[diethoxy(8-quinolinato)-titanium(IV) [Ti2(C9H6NO)2(C2H5O)6] complex with monoclinic space group P21/n. Manipulations were carried out under nitrogen, using standard Schlenk techniques. Titanium (IV) tetraethoxide was prepared from titanium (IV) tetrapropoxide (Fluka) and dry ethanol by the alkoxide exchange method and it was purified by vacuum distillation. 8-Hydroxyquinoline was added to the reagent in benzene. The mixture was stirred for a day and the solvent then removed under reduced pressure to furnish a yellow solid. The solid was crystallized from chloroform-hexane (3:4) to give pale-yellow crystals. The hydroxyquinolinate group chelates to the Ti atom in the centrosymmetric compound [Ti2(C9H6NO)2(C2H5O)6]. Two of the four ethoxy groups function as bridges, and the geometry of the six-coordinate Ti atom is that of an octahedron. The Ti–O–Ti angle is 107.3(1). The Ti–O and Ti–N bond lengths are in the range of 1.799(1)–2.065(1)Å and 2.294(1)Å respectively. The O–Ti–O, O–Ti–N are in the range of 72.7(1)–164.1(1)° and 75.3(1)–168.8(1)° respectively.
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Paper 9
Khavasi (2009) described chelates of the 8-hydroxy-2-methylquinolinate anion with Ti ion. In the centrosymmetric dinuclear compound [Ti2(C10H8NO)2(C2H5O)6] with monoclinic space group P21/n. The Ti atom is bonded to an N,O-bidentate quinolin-8-olate ligand, two terminal ethanolate anions and two bridging ethanolate anions in a distorted TiNO5 octahedral geometry. The Ti…Ti separation is 3.2948(13)Å. Manipulations were carried out under nitrogen, using standard Schlenk techniques. Titanium (IV) tetraethoxide was prepared from titanium (IV) tetrapropoxide (Fluka) and dry ethanol by the alkoxide exchange method and it was puried by vacuum distillation. 8-Hydroxyquinoline was added to the reagent in toluene. The mixture was stirred for a day and the solvent then removed under reduced pressure to furnish a yellow solid. The solid was crystallized from a dichloromethane n-hexane mixture to give yellow prisms of [Ti2(C10H8NO)2(C2H5O)6]. The Ti–O–Ti angle is 108.13(10)°. The Ti–O and Ti–N bond lengths are in the range of 1.808(3)–2.061(2)Å and 2.387(3)Å respectively. The O–Ti–O, O–Ti–N are in the range of 71.87(10)–161.18(11)° and 73.70(10)–161.53(12)° respectively.
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Paper 10
Two novel Fe(III) complexes with the HQ anion, namely [Fe8O4(O2CPh)10(HQ)4(OMe)2] and [Fe6O2(OH)2(O2CPh)10(HQ)2], were described by Christou (2016). Complex [Fe8O4(O2CPh)10(HQ)4(OMe)2] has P21/n space group whereas the complex [Fe6O2(OH)2(O2CPh)10(HQ)2] has Pbca space group.
Reactions using a variety FeIII starting materials and conditions, and that between preformed [Fe3O(O2CPh)6(H2O)3](NO3), HQ, and NEt3 in a 1:1:4 ratio in MeOH yielded a gray precipitate that gave dark red crystals of [Fe8O4(O2CPh)10(HQ)4(OMe)2] on recrystallization from CH2Cl2/hexanes. An alternative procedure giving a better yield of [Fe8O4(O2CPh)10(HQ)4(OMe)2] was developed involving the reaction of Fe(NO3)3 with HQ, PhCO2H, and NEt3 in a 2:1:4:6 ratio. Other ratios were also explored but proved inferior in terms of yield and/or purity of [Fe8O4(O2CPh)10(HQ)4(OMe)2]. Since complex [Fe8O4(O2CPh)10(HQ)4(OMe)2] contains two bridging MeO− groups, we explored whether the use of H2O as solvent might yield analogs with bridging OH− groups and possibly higher nuclearities. The 1:1 reaction of [Fe3O(O2CPh)6(H2O)3](NO3) with HQ did indeed yield a OH−-containing product, but it was the lower-nuclearity complex [Fe6O2(OH)2(O2CPh)10(HQ)2].
Complex [Fe8O4] lies on an inversion center and its structure contains an [Fe8(μ3-O)4]16+ core comprising a central [Fe2O2] rhombus whose oxide ions each connect to a triangular [Fe3O] unit. Additional monatomic bridges between [Fe2O2] and [Fe3O] units on each side are provided by μ-OMe−groups and μ-OR− arms of hqn− chelates. The conformation of the two [Fe3O] units about the bridging [Fe2O2] rhombus is anti, in accord with the inversion center. The peripheral ligation is provided by the 4 chelating/ bridging Q− groups and 10 benzoates in their common syn, syn η1:η1:μ-bridging mode.
The Fe–O–Fe angles are in the range of 92.74(9) –133.24(11)°. The Fe–O bond lengths are in the range of 1.844(2)–2.187(2)Å.
Complex [Fe6O2(OH)2(O2CPh)10(HQ)2] also lies on an inversion center and its structure contains an [Fe6(μ3-O)2(μ2-OH)2]12+ core consisting of two triangular [Fe3(μ3-O)] units, similar to those in [Fe8O4(O2CPh)10(HQ)4(OMe)2], joined together at two of their apexes by μ-OH− ions to give an almost planar Fe6 unit. The core of [Fe6O2(OH)2(O2CPh)10(HQ)2] can thus reasonably be described as that of [Fe8O4(O2CPh)10(HQ)4(OMe)2] without the central [Fe2O2] and with some changes to the bridging ligands. Each [Fe(μ-OH)Fe] linkage is additionally bridged by two syn,syn μ-benzoates. Also as in [Fe8O4(O2CPh)10(HQ)4(OMe)2], there is an additional monatomic bridge in each Fe3 triangle from the HQ− groups that chelate Fe2 and Fe2′ and bridge with their alkoxide arms the Fe2Fe3 and Fe2′Fe3′ edges; these monatomic bridges are trans. Peripheral ligation is completed by six additional η1:η1:μ- bridging benzoates.
The Fe–O–Fe angles are in the range of 93.16(6)–136.45(8)°. The Fe–O bond lengths are in the range of 1.8827(15)–2.0632(16)Å.
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Paper 11
Mabbs (1973) prepared µ-Oxo-bis-[bis-(2-methyl-8-hydroxyquinolinato) iron(iii)- chloroform complex with triclinic space group P1 ̄. Fe(2-mq)2,C1 (2-mq = 8-hydroxy- 2-methylquinolinato-) was first prepared as a black solid by treating stoichiometric amounts of 8-hydroxy-2-methylquinoline and anhydrous iron(iii) chloride in ethanol. [Fe(2-mq)2Cl] dissolved in ethanol was treated with triethylamine to produce [Fe(2-mq)2]2O which was recrystallised from chloroform. The Fe–O–Fe angle is 151.6(7)°. The Fe–O and Fe–N bond lengths are in the range of 1.760(11)–1.940(12)Å and 2.180(13)–2.211(13)Å respectively. The O–Fe–O and O–Fe–N angles are in the range of 114.8(5) –128.7(5)° and 78.0(5) –160.9(5)°.
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Paper 12
A tetra-iron(III) complex with the formula [Fe4(μ2-O)2Cl4(Hmq)4]·0.5H2O (Hmq= 2-methyl-8-hydroxyquinoline) was recently synthesised via solvothermal reaction and characterised by Liang et al.(2018). The reactions of FeCl3·6H2O and 2-methyl-8-hydroxyquinoline in the presence of Et3N in the 5:4:5 M ratio in a mixed CH3OH and CH3CN (1:3) solvent produced black crystals. The complex crystallise in monoclinic space group C2/c .
The geometry around each Fe centre is distorted trigonal bipyramidal with coordination to three oxygens, one nitrogen and one chlorine atom. Each pair of Fe centers is bridged by a μ2-phenoxo of mq , and two pairs of Fe centers are additionally linked by a μ2-O. Each Hmq group is coordinated to two Fe(III) ions in the 2.21 coordination mode. The shortest Fe⋯Fe distance between the neighboring tetranuclear units is 8.328(1)Å. The Fe–O–Fe angles are in the range of 107.49(1)–130.93(2)°. The average Fe…Fe distance is equal to 3.259(1) Å. The Fe–O bond lengths are in the range of 1.778(2)–2.060(2)Å. The Fe–N bond lengths are 2.146(3) and 2.147(3)Å. The Fe–Cl bond lengths are 2.233(1) and 2.235(1)Å. Antiferromagnetic exchange interactions dominate the magnetic properties.
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Paper 13
Telfer (2006) prepared tetranuclear double cubane, [Co4(mq)6Cl2] by reaction of the 8-hydroxyquinaldine ligand with a mixture of CoCl2 .6H2O and Co(OAc)2 .4H2O. The complex crystallizes in triclinic space group P1-. Two of the cobalt (II) ions coordinate to two deprotonated bidentate (mq) ligands, while the other two metal centers bind one bidentate (mq) ligand and one chloro ligand. The oxygen donor atoms of the (mq) ligands bridge either two or three cobalt (II) centers to build up the cubane structure. The Co–O–Co angles are 93.0(1), 98.7(1) and 108.2(2)°. The Co–O and Co–N bond lengths are in the range of 2.003(3)– 2.242(4)Å and 2.102(5)–2.129(4)Å. The Co–Cl bond length is 2.289(2)Å. The Co(II) centers in the double cubane complex [Co4(mq)6Cl2] is strongly antiferromagnetically coupled to each other at low temperature.
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Paper 14
Ray et al. (2007) explored the reactions of cobalt (II) with HQ as the ligand. Reaction of NaQ in MeOH with Co(OAc)2. 4H2O and NaN3 in ratio 4:3:4 in air produces the red plate-like crystals of complex [Co3(N3)4Q4(OH2)2]. 2H2O, were obtained by slow evaporation in DCM/EtOH (1:1) solution after 15 days. The complex crystallise in orthorhombic space group Pbca. The structure consists of homometallic mixed valent cobalt atoms linked by double EO azido bridges. The Co(III) and Co(II) ions in CoN4O2 environments and have slightly distorted octahedral geometries. For Co(III) two nitrogen from Q and two nitrogen atoms from EO azides occupy two in-plane positions and two oxygen atoms from Q occupy two apical positions. Around Co(II) four nitrogen atoms from EO azides occupy the four in-plane positions and two oxygen atoms from water molecules occupy apical positions. The Co(II)–N(azido) distances (2.128(4) and 2.172(4)Å) are longer than Co(III)–N(azido) distances (1.958(4) and 1.961(4) Å). The Co(III)–N(mq) bond lengths are 1.904(4) and 1.920(4)Å. The bond angles of CoIII–N(azido)–CoII are in the range between 99.64(16)° and 101.26(16)°. The Co(III)…Co(II), separation through EO azide 3.160Å. The Co(III)–O bond lengths are 1.909(3) and 1.920(3)Å. The Co(II)–O bond length is 2.026(4)Å. The O–Co(III)–O, O–Co(II)–O are 177.21(15) and 180° respectively. The O–Co(III)–N, O–Co(II)–N are in the range of 85.16(15)–92.71(16)° and 86.89(16)–93.11(16)° respectively. The N–Co(III)–N, N–Co(II)–N are in the range of 82.69(16)–175.88(17)° and 74.03(14)–180° respectively.
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Paper 15
Xu (2012) prepared A novel decanuclear Co(II) cluster, [Co10(Q)12(μ6-CO3)4]·2.5DMF (Q = 8-hydroxyquinoline). The red octahedral crystals were synthesized under solvothermal conditions. HQ was added to the mixture of Co(OAc)2·4H2O and N,N-dimethylformamide (DMF) in presence of trimethylamine. Single-crystal X-ray analysis reveals that compound crystallizes in the cubical space group Pa3ˉ. The asymmetric unit contains four crystallographically independent Co ions, four Q ligands and two CO32− anions. Each crystallographically independent Co(3) atom lies on the C3 axis and is surrounded by the other three Co atoms (Co(1), Co(2) and Co(4)) to form the decanuclear cluster by three-fold symmetry operation. All cobalt ions are coordinated to Q ligands and CO32− anions to form an approximate octahedron. Co(1) and Co(2) are coordinated to two μ2-O atoms from CO32− anions, two N atoms and two μ2-O atoms from chelated Q molecules. Another type of cobalt sites (Co(3) and Co(4)) is coordinated to three μ2-O atoms from Q and three μ2-O atoms from CO32− anions.
The Co–O bond lengths are ranged from 2.049(3) to 2.188(3) Å. The Co–N bond lengths are from 2.083(3) to 2.116(3) Å. The Co-μ2-O–Co angles (96.64(13)–99.59(14)°) are larger than the Co-μ3-O–Co angles ranging from 94.03(12) to 97.74(13)°. The nearest distance of Co–Co between two neighbouring clusters is approximate 7.985Å. The magnetic study shows that there exists an AF interaction within the complex.
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Paper 16
Turner (2014) prepared [Co4(OQ)4(BQ)2] and [Co4(OQ)8] complexes (where OQ = 8-Hydroxyquinolinolate and BQ = 2,7’-biquinoline-8,8’–diolate).
8-Hydroxyquinoline, SmCo5, and 1,2,4,5-tetramethylbenzene were placed in a thick-walled glass tube. The tube was evacuated, sealed, and placed in a furnace at 270 0C for 7 days. Microscopic yellow crystals were handpicked from a red glassy material and determined by X-ray crystallography to be [Co4(OQ)4(BQ)2]. The BQ ligand is the result of a 2,7’-coupling between two 8-quinolinolate anions, yielding a biquinoline- 8,80-diolate ligand. The complex crystallises in the monoclinic space group C2/c with half of the complex in the asymmetric unit. Both crystallographically unique cobalt centres have distorted N2O4 octahedral coordination environments comprising two chelating quinolinolate groups (one from the OQ ligand and one from the BQ ligand) and two oxygen atoms bridging the quinolinolate groups that are chelated to neighbouring cobalt atoms. The core of the complex can be viewed as two face-sharing pseudo-cubane motifs with Co…Co distances of 3.2Å. The two unique OQ ligands adopt μ2-2.21 and μ3-3.31 coordination modes. The fused BQ ligand chelates to two metals with one of the oxygen atoms coordinated to both. The Co–O bond lengths are within 2.000(2)–2.210(2)Å. The Co–N distances lie in range of 2.104(2)–2.140(2)Å.
8-Hydroxyquinoline, Co powder, 1,3,5-tri-tert-butylbenzene, and six drops of mercury were placed in a thick-walled glass tube. The tube was evacuated, sealed, and placed in a furnace at 200 0C for 7 days. Red single crystals were manually isolated and determined by X-ray diffraction to be [Co4(OQ)8]. The compound crystallises in the monoclinic space group C2/c and half of the complex is contained within the asymmetric unit. The core of the complex is similar to that of complex [Co4(OQ)4(BQ)2], with a face-sharing double pseudo-cubane structure. Both unique cobalt atoms adopt distorted octahedral coordination environments. The cobalt atoms at either end of the complex are coordinated to one chelating OQ ligand, one chelating μ3-OQ ligand that also bridges to both central metals, and two oxygen atoms from μ2-OQ ligands that chelate to the central metals (N2O4). The central cobalt atoms are chelated to two μ2-OQ ligands, which also bridge to other metals, and coordinated to two oxygen atoms from the μ3-OQ ligands attached to the other central metal. Bond lengths are as expected, with the shortest Co–O bond involving the simple chelating OQ ligand (2.0058(14)Å) and those involving m-oxygen atoms being longer (2.0863(12)–2.2708(15)Å). Co–N bonds do not vary greatly and lie in the range of 2.1042(14)–2.1861(14)Å.
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Paper 17
Cobalt and manganese ions clusters with the related compound 8-oxyquinolinate have been described by Baruah et al.(2015), including a tetranuclear Co cluster [Co4(oxyQ)6Cl2] capable of reacting with further cobalt (ii) chloride under solvothermal conditions in dimethylformamide to become decanuclear [Co10(oxyQ)12(μ6-CO3)4].(DMF)·H2O complex. The complex crystallise in cubic space group Pa3ˉ. Five cobalt (II) ions of the cluster are individually ligated to two oxyquinolinate chelating ligands. These chelating oxyquinolinate ligands are also involved in the μ2-Ooxyquinolinate bridge to connect neighbouring cobalt ions. This set of cobalt ions of the cluster is anchored to two independent oxygen atoms of two carbonate ligands. Thus, these cobalt ions are in the N2O4 type of an octa-coordinated environment. On the other hand, there are other five cobalt ions linked to three oxygen atoms of bridging carbonates and three oxygen atoms of bridging oxyquinolinates. This makes an O6 octahedral environment around these cobalt (II) ions. A similar synthetic approach was used to produce the decanuclear Mn cluster.
Both clusters possessed bridging carbonate ligands along with the oxyquinolinate ligands and were shown to display anti-ferromagnetic behaviour.
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Paper 18
Ray (2008) prepared a new Ni4 distorted cubane complex [Ni4(μ3-OMe)4Q4(MeOH)4] (where Q is the anion of 8-quino-linol). The large yellow-green crystals suitable for X-ray structure determination were obtained by reaction of Ni(O2CCH3) 4H2O, NaOH and NaQ in 1:1:1 molar ratio in MeOH medium at room temperature under reflux for 0.5 h. Single crystals were obtained by the slow evaporation of a dichloromethane solution of compound layered with methanol in 1:1 (v/v) ratio. The complex crystallizes in tetragonal I41/a space group.
The structure incorporates a distorted [Ni4(OMe)4] cubane core with two different types of Ni2O2 faces having Ni…Ni separations of 3.07 and 3.16 Å, respectively, where the μ3-O bridges are derived from methanol molecules. The peripheral coordinations around each distorted octahedral Ni(II) ion is completed by four terminal MeOH and four Q ligands.
The coupling between adjacent Ni ions is moderately antiferromagnetic for longer separation and the shorter separation feature a weak ferromagnetic super-exchange
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Paper 19
Liang (2012) prepared A new nickel(II) complex with 5,7-dichloro-8-hydroxylquinoline (H–ClQ), [NiCl(ClQ)(H–ClQ)(μ3-Cl)Ni(ClQ)(CH3CH2OH)(H–ClQ)] .CH3COCH3.
NiCl2 6H2O, H–ClQ, ethanol and acetone were placed in a thick Pyrex tube. The mixture was frozen in liquid N2, vacuumized and sealed. Then it was heated to and kept at 80 °C for three days. Green block crystals were harvested for X-ray diffraction analysis. The complex crystallise in monoclinic space group P21/n. Two Ni(II) complex units are bridged by a –Cl. Two Ni(II) atoms are chelated by two bidentate 5,7-dichloro-8-hydroxylquinolines and coordinated by one terminal Cl atom or ethanol ligand and one -Cl in a distorted octahedral coordination environment. The intraligand angles [av. 79.19(18)°] of N(1)–Ni–O(1) in the five-membered chelate rings are considerably smaller than the ideal value of 90°. The separation distance of Ni(1)–Ni(2) is 4.3554(3)Å. Depending on the linking groups, the Ni–Cl distance is either 2.3836(18) or 2.4375(16)Å. The average Ni–N and Ni–O distances are 2.059(5) and 2.0952(4)Å. In terms of bonding angle, the N–Ni–N are 173.59(19) and 177.52(19)°, and the N–Ni–O, N–Ni–O, Cl–Ni–Cl, N–Ni–O, N–Ni–O bond angles deviate from 90° more or less, suggesting a severe distortion in the Ni(II) octahedron. The Ni–Cl–Ni is 128.16(7)°. Each nickel(II) is coordinated by a neutral 5,7-dichloro-8-hydroxylquinoline.
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Paper 20
Liu (2019) prepared [Ni7(μ2-L1)6(μ3-L1)2(OAc)2(μ7-L2)(OCH3)]·CH3OH·CH3CN and [Ni7(μ2-L1)6(μ3-L1)3(SCN)2(μ7-L2)(CH3CN)]·(CH3OH)2·CH3CN (where HL1 = 8-hydroxyquinoline, H3L2 = 1,1,1-tris-(hydroxymethyl)ethane).
A mixture of Ni(OAc)2·6H2O, HL1, H3L2, NaHCO3, acetonitrile, and methyl alcohol was sealed in a 25 mL Teflon-lined stainless steel autoclave. The autoclave was heated at 120 °C for 72 h then cooled slowly to room temperature. Green blocky crystals of [Ni7(μ2-L1)6(μ3-L1)2(OAc)2(μ7-L2)(OCH3)]·CH3OH·CH3CN were harvested. The complex crystallise in triclinic space group P1̅. The crystallographic unit contains seven NiII ions, two acetic anions, one deprotonated methanol, six μ2-L1, two μ3-L1, and one μ7-L2. The disklike metal node consists of a hexanuclear Ni(II) wheel and a central Ni(II) center, and the seven Ni ions are six-coordinated respectively adopting distorted-octahedral geometries. The Ni1 are occupied by two μ2-O atoms from μ2-L1, O from μ3-L1, and O from an acetic anion, N from μ3-L1 and O from μ7-L2. The Ni2 are occupied by N from μ2-L1, O from μ3-L1, O from μ7-L2, and O from an acetic anion, two μ2-O atoms from μ2-L1. The Ni3 are occupied by two μ2-O atoms and one N atom from μ2-L1, O from μ3-L1, N from μ2-L1 and O from μ7-L2. The Ni4 occupied by O from μ3-L1, two μ3-O atoms from μ7-L2, and O from deprotonated methanol, O from μ3-L1 and O from μ7-L2. The Ni5 are occupied by two μ2-O atoms from μ2-L1, N from μ3-L1, O from μ7-L2, N from μ -L1 and O from μ3- L1. The Ni6 occupied by O from μ7-L2, O from deprotonated methanol, two μ1-O atom from an acetic anion and two μ2-O atoms from μ2-L1. The Ni7 occupied by two μ2-O atoms and one N atom from μ2-L1, O from μ7- L2, N from μ2-L1 and O from deprotonated methanol. The values of Ni−O and Ni−N bond lengths are in the range of 1.995(6)−2.248(6)Å and 2.032(8)−2.114(8)Å respectively. Three Ni(II) ions, coordinated with one μ3-O, forming a triangular conformation, and seven Ni(II) ions are bridged by six μ3-O in this way to form the disklike node configuration.
The complex [Ni7(μ2-L1)6(μ3-L1)3(SCN)2(μ7-L2)(CH3CN)]·(CH3OH)2·CH3CN was synthesized with a protocol different from that of [Ni7(μ2-L1)6(μ3-L1)2(OAc)2(μ7-L2)(OCH3)] by replacing Ni(OAc)2·6H2O with NiSO4·6H2O and adding NaSCN. Green flaky crystals were obtained. The complex crystallise in monoclinic space group P21/c. In the crystallographic unit, there are seven Ni(II) ions, two thiocyanate anions, an acetonitrile, six μ2-L1, three μ3-L1, and one μ7-L2. The disklike metal node is similar to that of [Ni7(μ2-L1)6(μ3-L1)2(OAc)2(μ7-L2)(OCH3)], composed of a hexanuclear Ni(II) wheel and a central Ni(II) center. The seven Ni ions are six-coordinated respectively adopting distorted octahedral geometries, and the details will not be described. The values of Ni−O and Ni−N bond lengths are in the range of 1.017(3)−2.342(3)Å and 2.031(4)−2.093(4)Å respectively. Three Ni(II) ions, coordinated with one μ3-O, form a triangular conformation, and seven Ni(II) ions are bridged by six μ3-O to form a disklike node configuration.
Magnetic measurements of both complexes show ferromagnetic coupling between the ions. …………………………………………………………………………………………………
Paper 21
Floriani (1983) prepared a tetranuclear copper (i) carbonyl complex [Cu(Q)(CO)]4 by reaction of Copper(I) chloride with a solution of sodium 2-methylquinolin-8-olate in tetrahydrofuran under a pressure of 60 atm of CO a t 65 0C. Copper and oxygen atoms arranged in acubane-like structure. The four copper atoms are at the vertices of a tetrahedron. Each copper has a pseudo-tetrahedral co-ordination provided by the bidentate quinolinolato anion, carbon monoxide, and the two bridging oxygens. Cu−O bond distances range from 2.01(2) to 2.08(2)Å and Cu−N from 2.00(2) to 2.12(2)Å. The Cu…C separations vary from 3.514(1) to 3.856(1)Å and the average Cu…Cu…Cu angle is 60.0°.
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Paper 22
SHARMA (1985) prepared tetrahedrally distorted square planar copper-HQ complexes with the formula [Cu(Q)(P)]2 and [Cu(Q)(S)]2 where HQ = 8-hydroxyquinoline and P and S are deprotonated phthalimide and succinimide respectively. Copper(ii) phthalimide and Copper(ii) suscinimide were prepared by the same method. The methanolic solutions of copper(ii) imide and 8-hydroxyquinoline were mixed in the ratio of 1:1 and then refluxed on a water bath for about half an hour which gave the crystals a yellowish-green colour. The magnetic properties of the complexes were examined and their susceptibilities at various temperatures pointed to a moderate antiferromagnetic superexchange interaction within a single dimeric unit.
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Paper 23
Kasai (1985) prepared the molecular structure of an anhydrous [Zn(C9H6NO)2]4 molecule in which distinct hexa- and penta-coordination geometries are expressed by two crystallographically independent Zn atoms. The complex crystallise in triclinic space group P1-. The molecule is centrosymmetric; four [Zn(C9H6NO)2] units being connected by oxygen atoms of 8-quinolate ligands. The two [Zn(C9H6NO)2] units connected by two bridging oxygen atoms form an asymmetric unit. Two asymmetric units related by a center of symmetry, connected by two bridging oxygen atoms, make the whole molecule tetrameric. The Zn−O−Zn angles are in the range of 96.6(2)−106.7(2)°. The Zn−O and Zn−N bond lengths are in the range of 1.956(4)−2.176(4)Å and 2.047(4)−2.178(5)Å respectively. The O−Zn−O and O−Zn−N angles are in the range of 77.0(2)−174.5(2)° and 76.9(2)−153.2(2)° respectively. The N−Zn−N angles are 90.2(2) and 116.6(2)°.
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Paper 24
Weng Ng (2009) prepared centrosymmetric [Zn4(C9H6NO)6(C2H3O2)2] .2H2O by reaction of zinc acetate dihydrate and 2-methyl-8-hydroxyquinoline (in 1:1 ratio) were loaded into a convection tube. The tube was filled with dry methanol and kept at 333 K. Crystals were collected a week. The complex crystallise in triclinic space group P1-. the Zn (II) atom that is bonded to one O atom of the acetate group is chelated by a quinolin-8-olate anion. This Zn atom is also bonded to the oxide O atoms of two other quinolin-8-olate anions, which themselves engage in chelation to the other Zn (II) atoms. The Zn (II) atom is five- coordinate in a square-pyramidal coordination geometry. The second Zn (II) atom is six-coordinate as it is linked to two oxide O atoms of the anions that chelate to the acetate-bound metal atom, and is chelated by two quinolin-8-olate ligands. The Zn−O−Zn angles are in the range of 94.70(8)−108.21(9)°. The Zn−O bond lengths are in the range of 2.000(2)−2.265(2)Å and Zn−N bond lengths are 2.093(3)−2.111(3)Å. The O−Zn−O and O−Zn−N angles are in the range of 76.48(8)−174.06(8)° and 75.65(9)−156.85(9)° respectively. The N−Zn−N angles is 97.67(10)°.
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Paper 25
Weng Ng (2009) prepared centrosymmetric dinuclear [Zn2(C10H8NO)2(CH3CO2)2(CH3OH)2] complex by reaction of zinc acetate and 2-methyl-8-hydroxyquinoline (in 1:2 ratio) were loaded into a convection tube. the tube was filled with dry methanol and kept at 333 K. Crystals were collected after several days. The complex crystallise in triclinic space group P1-. The Zn atom within a distorted NO4 trigonal–bipyramidal coordination geometry. The Zn−O−Zn angle is 104.81(16)°. The Zn−O bond lengths are in the range of 1.968(4)−2.092(3)Å and Zn−N bond length is 2.134(4)Å. The O−Zn−O and O−Zn−N angles are in the range of 75.2(2)−142.5(2)° and 79.8(2)−155.0(2)° respectively.
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Paper 26
Lewinski (2012) prepared tert-butylzinc complex stabilized by the quinolinate ligand [tBuZn(q)]3, the pentanuclear oxo cluster [(tBu)3Zn5(μ4-O)(q)5], and the tetranuclear hydroxo cluster [Zn(q)2]2[tBuZn(OH)]2.
Compound [tBuZn(q)]3 crystallizes in the P21/c space group and its molecular structure consists of three discrete monomeric units bridged by the oxygen atoms of the chelating quinoline ligands. The central core comprises a puckered six-membered Zn3O3 ring with the coordination environment of ZnCNO2 zinc atoms distorted from an ideal tetrahedral geometry due to the small bite angle of the quinoline ligand. The fourth coordination site on each zinc center is filled by the pyridine nitrogen atom of the quinolinate ligand. The Zn−N and Zn−O distances (average 2.105 and 2.036Å respectively). The O−Zn−O angles are 94.41(9), 94.01(10) and 97.48(9)°.
Compound [(tBu)3Zn5(μ4-O)(q)5] crystallizes in the P-1 space group and exists as an pentanuclear cluster centered by the encapsulated μ4-O2- ion. Formally its composition may be viewed as a cluster in which ZnO molecule is entrapped by three parent tBuZn(q) moieties and one bischelate Zn(q)2 moiety. Two zinc centers, coordinated by the oxygen and nitrogen atoms of two quinolinate ligands, and by an O ion have an idealized trigonal bipyramid geometry with the ZnN2O2 environment. Three other zinc centers have an idealized tetragonal geometry with different enviroments, [CZnN(μ-O)( μ4-O)] , [CZn(μ-O)3], and [CZn(μ-O)2(μ 4-O)]. The Zn−O and Zn−N bond lengths are in range of 1.939(3)−1.976(3)Å and 1.981(2)−2.077(4)Å. The Zn−O−Zn are in the range of 98.16(13)−119.15(14)°.
Compound [Zn(q)2]2[tBuZn(OH)]2 crystallizes in the P1 ̄ space group. The molecular structure represents a centrosymmetric dimer formed by the association of two dinuclear [Zn(q)2][tBuZn(OH)] moieties comprising the bis-chelate Zn(q)2 and tBuZnOH units. The basic skeletal arrangement can be described as an inversion-related, corner-removed, face-shared cubane. There are two four-coordinate zinc atoms with the terminally Zn-bound tert-butyl groups, the CZn(Oquinolate)2(Ohydroxy) core, and two six-coordinate zinc atoms with peripheral ligation provided by four chelating quinolinate groups. The most striking point of the structure is the presence of the Zn−OH moiety. The hydroxyl groups act as μ3-bridging ligands between the tetrahedral and octahedral zinc atoms with a Zn−O distance of 2.006(4) and 2.091(4)Å. The Zn−O are in range of 2.006(4)−2.094(4)Å and the Zn−N bond lengths are 2.136(5)−2.153(5)Å. The Zn−O−Zn are in the range of 98.64(17)−99.99(16)°.
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Paper 27
Liang (2013) prepared [Zn2(ClQ)4(CH3OH)2] and [Zn2(ClIQ)4] (H-ClQ = 5,7-dichloro-8-hydroxylquinoline, and H-ClIQ = 5-chloro-7-iodo-8- hydroxylquinoline).
Yellow block crystals of [Zn2(ClQ)4(CH3OH)2] was prepared by reaction of ZnCl2.2H2O, H-ClQ, methanol, NaOH solution were placed in a thick Pyrex tube. The mixture was frozen by liquid N2, vacuumed and sealed. Then it was heated at 80 0C for three days. The complex crystallise in triclinic space group P1 ̄. The complex looks like a kite. In the centrosymmetric binuclear complex, the Zn(1) atom that is bonded to one O atom of methanol is chelated by two quinolin-8-olate anions meanwhile one oxide O atom of the anion is linked to Zn(1A). The Zn(1) atom is also bonded to the oxide O atom of another quinolin-8-olate anion. Thus binuclear structure is formed by two μ2-O atoms, and the Zn atom is six-coordinate octahedral geometry. The Zn−O distances [2.032(3) and 2.071(3)Å] involving quinolin-8-olate are substantially shorter than the Zn−N distances [2.109(3) and 2.126(3)Å].
Using H-ClIQ and triethylamine to replace H-ClQ and NaOH solution, the procedure is similar to complex [Zn2(ClQ)4(CH3OH)2]. Yellow rhombic crystals suitable for X-ray diffraction analysis were harvested [Zn2(ClIQ)4]. The complex crystallise in monoclinic space group P21.
Similar to complex [Zn2(ClQ)4(CH3OH)2], the whole molecular complex seems also like a kite. Whilst in the centrosymmetric binuclear complex, the Zn(1) atom is only chelated by two quinolin-8-olate anions without the coordinated methanol; one oxide O atom of the anion is linked to Zn(1A). The Zn(1) atom is laso bonded to the oxide O atom of another quinolin-8-olate anion. Thus binuclear structure is formed by two μ2-O atoms. The Zn atom of complex is five-coordinate in a square- pyramidal geometry.
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Paper 28
Walker (2013) prepared Three new zinc 8-quinaldinolate complexes have been obtained from rearrangement reactions at elevated temperatures [Zn3(MQ)6], [Zn4Cl4(MQ)4] and [Zn4Cl2(MQ)6] (MQ = 8-quinaldinolate).
Compound [Zn3(MQ)6] was prepared by reaction of Zn(MQ)2 and 1,2,4,5-tetramethylbenzene (TMB) were placed in an evacuated sealed tube and heated at 270 0C for 6 days, resulting in a mixture of red crystals and brown amorphous material. The complex crystallise in triclinic space group P1 ̄.
The complex contains no internal symmetry and hence the entire complex resides within the asymmetric unit. The trinuclear complex adopts a bent geometry with the central zinc atom having a distorted octahedral coordination geometry (N2O4) and the peripheral zinc atoms having distorted square pyramidal coordination geometries (N2O3). Four of the six MQ ligands coordinate in 2.21 coordination modes, i.e. chelating to one metal with the oxygen further coordinating to an adjacent metal atom. Two of these ligands chelate to the central zinc, with one each on the terminal zinc atoms. The terminal metals also have MQ ligands in a purely chelating coordination mode. Overall, this leads to the central zinc being connected to each of the terminal zinc atoms by two μ2 oxygen atoms. The Zn−O−Zn angles are in the range of 100.10(15)−106.37(15)°. The Zn−O and Zn−N bond lengths are in the range of 1.980(3)−2.175(4)Å and 2.110(4)−2.193(4)Å respectively.
Compounds [Zn4Cl4(MQ)4] and [Zn4Cl2(MQ)6] were prepared by reaction of mixtures of Zn(MQ)2 and anhydrous ZnCl2 were combined with TMB and placed in an evacuated sealed tube at 270 0C for 6 days. The 3:1 reaction, and the 1:1 reaction for Zn(MQ)2 and ZnCl2 respectively. After cooling, the deep-red crystalline product was hand-picked from the mixture. Owing to the mixture of products, bulk analysis was conducted by PXRD, which showed the presence of [Zn4Cl4(MQ)4] and [Zn4Cl2(MQ)6] as the only crystalline products in both cases.
Both of the heteroleptic complexes are tetranuclear, with the four Zn atoms. Complex [Zn4Cl4(MQ)4] crystallises in P-1 with half of the complex contained within the asymmetric unit. The two unique zinc centres have different coordination environments. One zinc atom adopts an almost ideal tetrahedral coordination geometry with two chloride ligands and two μ2-oxygen atoms from quinaldinolate (MQ) ligands. The other zinc atom is coordinated by two (N,O)-chelating MQ ligands and adopts a distorted tetrahedral geometry. Overall, the complex has a cyclic form with the four zinc atoms being bridged by the 8-quinaldinolate oxygen atoms. Given that the bridging mode between the Zn atoms is similar. The Zn−O−Zn angles are 112.48(6) and 115.85(6)°. The Zn−O bond lengths are in the range of 1.9635(12)−1.9931(13)Å. The Zn−N bond lengths are 2.0463(16) and 2.0742(16)Å. The Zn−Cl bond lengths are 2.1884(5) and 2.2847(5)Å.
Complex [Zn4Cl2(MQ)6], crystallises in the triclinic space group P-1 with the asymmetric unit containing half of the complex. The two zinc atoms both have distorted square pyramidal geometries with different ligands in their coordination spheres. One of the Zn has a coordination sphere of ClNO3 and is chelated by one MQ ligand with two Zn–O interactions from MQ ligands chelated to adjacent metal atoms and one terminal chloride ligand. The second Zn has an N2O3 coordination sphere with two chelating MQ ligands and a Zn–O interaction from a neighbouring ligand. All three MQ ligands adopt 2.21 coordination mode. The Zn−O−Zn angles are in the range of 100.34(7)−108.81(8)°. The Zn−O and Zn−N bond lengths are in the range of 1.9879(17)−2.0981(7)Å and 2.0127(19)−2.168(2)Å. The Zn−Cl bond length is 2.2592(9)Å.
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Paper 29
Williams (2015) prepared a series of (8-quinolinolato) zinc ethyl complexes, [LZnEt] (where L = 8-Hydroxyquinoline derivatives ligands). The complexes were synthesised by reactions of diethyl zinc in toluene was added, dropwise with stirring, to a solution of 8-hydroxyquinoline in toluene. The solution was stirred for 12 h, after which time a yellow precipitate had formed. Single crystals, suitable for X-ray diffraction experiments, were isolated for compounds Zn-A, Zn-D from THF–hexane and toluene solutions, respectively.
General synthesis of initiators Zn-A, B, C, D, E and G, numbering scheme included
The crystal structure of Zn-A shows the complex to be a dimer with bridging phenoxide oxygen atoms. The geometry at the zinc centre is noticeably distorted with the angles involving the ethyl ligand. The Zn…Zn separation is 3.09986Å. The Zn–O bond lengths are 2.0776(14) and 2.0761(15)Å. The Zn–N and Zn–C bond lengths are 2.0866(17) and 1.984(2)Å respectively. The O–Zn–O angle is 83.46(6)°, N–Zn–O angles are 80.54(6) and 105.43(6)°, C–Zn–O angles are 129.36(8) and 117.05(8)°. The C–Zn–N angle is 128.80(8)°.
The crystal structure of Zn-D shows a trimeric, cyclic structure based on three EtZn-D units. The Zn3O3 ring has a “two-up one-down” arrangement for the quinolinolate ligands. All three zinc centres have distorted tetrahedral coordination geometries with angles in the ranges 81.20(7)–125.24(10)°, 80.85(7)–128.93(9)° and 80.57(7)–130.87(11)° at Zn1, Zn2 and Zn3 respectively. The Zn–O, Zn–N and Zn–C bond lengths are in the range of 2.0116(17)–2.0537(16)Å, 2.083(2)–2.097(2)Å and 1.975(3)–1.979(3)Å respectively.
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Paper 30
BARUAH (2015) prepared Tetra-nuclear zinc-8-oxyquinolate cluster. [Zn4(oxyQ)6X2].(solvent)2 (when X = Cl, Solvent = dimethylformamide, dimethylacetamide and dimethysulphoxide ; X = Br, solvent = dimethylformamide, oxyQ = quinolinate anion).
Complex [Zn4(oxyQ)6X2].(solvent)2 (when X = Cl) was synthesise by reaction of a solution of 8-hydroxyquinoline in methanol, zinc chloride was added and stirred for 15–20 min. A white precipitate was formed. Recrystallization of the white precipitate from DMF, DMA and DMSO yielded their corresponding solvates. The Clusters are isostructural; each belong to triclinic space group P-1 space group. Clusters have similar tetra-nuclear zinc core. Metal ions in the clusters are in two different types of environments. The zinc sites holding the halide ions are penta-coordinated while the other two zinc sites are hexa-coordinated. A procedure similar to that of [Zn4(oxyQ)6X2].(solvent)2 (when X = Cl) was used for preparation of complex [Zn4(oxyQ)6X2].(solvent)2 (when X = Br) in which zinc bromide was used in place of zinc chloride.
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Paper 31
Liang (2018) prepared two zinc(II) complexes, [Zn4(HOQ)6Ac2] (HOQ = 8-hydroxylquinoline) and [Zn4(MeQ)6Ac2] (MeQ = 2-methyl-8-hydroxylquinoline).
Reaction of Zn(OAc)2 · H2O, HOQ, methanol and chloroform were placed in a thick Pyrex tube, then the mixture was frozen by liquid N2, evacuated under vacuum, sealed and reacted at 110 °C for three days. Received yellow block crystals of complex [Zn4(HOQ)6Ac2].
Same processing step for complex [Zn4(HOQ)6Ac2] was carried out using MeQ instead HOQ. Yellow crystals of complex [Zn4(MeQ)6Ac2] were generated after three days. Both complexes crystallise in triclinic space group P1-. For complex [Zn4(HOQ)6Ac2] the Zn atom chelated by two 8-hydroxylquinoline anions is six coordination geometry, while the Zn atom, which is chelated by a 8-hydroxylquinoline anion and an acetate anion, is five coordinate in a square-pyramidal coordination geometry. For complex [Zn4(MeQ)6Ac2], compared with complex [Zn4(HOQ)6Ac2], in addition to the ligand (8-hydroxyquinoline is replaced by 2-methyl-8-hydroxyquinoline), the other are the same.
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