Hexacoordinate triphenylantimony(V) complex with tridentate bis-(3,5-di-tert-butyl-phenolate-2-yl)-amine ligand: Synthesis,NMR and X-ray study

The oxidative addition reaction of 4,6-di-tert-butyl-N-(2-hydroxy-3,5-di-tert-butyl-phenyl)-o-iminobenzoquinone (IBQ) to triphenylantimony(III) proceeds with the migration of hydroxyl-proton to a nitrogen atom to form tridentate O,N,O′-coordinated bis-(3,5-di-tert-butyl-phenolate-2-yl)-amine ligand. In accordance with ¹H, ¹³C, DEPT NMR data, the new hexacoordinate complex [bis-(3,5-di-tert-butyl-phenolate-2-yl)-amine]triphenylantimony(V), [(AP-AP)H]SbPh₃ (1) in solution has a C_s symmetry plane leading to the equivalence of two O,N-chelate o-aminophenolato moieties. The molecular structure of 1 · acetone was studied by a single-crystal X-ray. Compound 1 was found to be air-stable both in solid and in solution. Its oxidation by PbO₂ leads to paramagnetic [4,6-di-tert-butyl-N-(3,5-di-tert-butyl-phenolate-2-yl)-o-iminobenzosemiquinolato]triphenylantimony(V), [(AP-ISQ)]SbPh₃ (2).     

Intermediates of Asymmetric Oxidation Processes Catalyzed by Vanadium(V) Complexes

The [VO(acac)₂]/Schiff base [R-2-(N-3,5-di-tert-butylsalicylidene)amino-2-phenyl-1-ethanol, S-2-(N-3,5-di-tert-butylsalicylidene)amino-3,3-dimethyl-1-butanol, S-2-(N-3,5-di-tert-butylsalicylidene)amino-3-methyl-1-butanol, or R-2-(N-3,5-di-tert-butylsalicylidene)amino-3-phenyl-1-propanol]/H₂O₂ catalytic systems for the asymmetric oxidation of sulfides and the [VO(acac)₂]/(3bR,4aR)-2-(3,4,4-trimethyl-3b,4,4a,5-tetrahydrocyclopropa[3,4]cyclopenta[1,2-c]pyrazol-1-yl)ethanol/tert-butyl hydroperoxide/TBHP and VO(OAlkyl)₃/[2,2]paracyclophane-4-carboxylic acid N-(1,1-dimethylethyl)-N-hydroxamide/TBHP catalytic systems for the asymmetric epoxidation of allylic alcohols were studied using ¹³C, ⁵¹V, and ¹⁷O NMR spectroscopy. The key intermediates of these systems (peroxo and alkylperoxo complexes of vanadium(V)) were detected, their structures in solution were studied, and the reactivity was evaluated.     

Synthesis of aromatic tetracyclic tin compounds by template and transmetallation reactions: Alkyl vs aryl migration from tin to nitrogen

The syntheses of [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]diphenyltin (1) and [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]dichloro-phenyl-stannate (2) by template reactions using 3,5-di-tert-butylcatechol, aqueous ammonia and SnPh₂Cl₂ are reported. We also report the syntheses of compounds 2, [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]trichloro-stannate (4), [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)methylamine]chloro-methyltin (5), and [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)-n-butylamine]n-butyl-chlorotin (6) and [bis(3,5-di-tert-butyl-2-hydroxy-2-phenyl)amine]n-butyl-dichloro-stannate (7), performed by transmetallation reactions of the octahedral zinc coordination compound Zn[3,5-di-tert-butyl-1,2-quinone-(3,5-di-tert-butyl-2-hydroxy-1-phenyl)imine]₂ (3) with SnPhCl₃ or SnPh₂Cl₂, SnCl₄, SnMe₂Cl₂, Sn(nBu)₂Cl₂ and Sn(nBu)Cl₃, respectively. The X-ray diffraction structures of compounds 1, 2, 4 and 6 are reported. The transmetallation reactions with Sn(alkyl)₂Cl₂ afforded pentacoordinated tin compounds, where an alkyl group migrated from tin to nitrogen, while similar reactions with Sn-Ph compounds did not present any phenyl group migration.     

Photochemistry of <Emphasis Type="Italic">N</Emphasis>-substituted salicylic acid amides

The products of photolysis of N-substituted salicylic acid amides, viz., 2-hydroxy-3-tert-butyl-5-ethylbenzoic acid N-(4-hydroxy-3,5-di-tert-butylphenyl)amide (1) and 2-hydroxybenzoic acid N-[3-(4-hydroxy-3,5-di-tert-butylphenyl)prop-1-yl]amide (2), in heptane were studied by optical spectroscopy and stationary and nanosecond laser photolysis (Nd: YAG laser, 355 nm). It was shown by the method of partial deuteration of amides 1 and 2 that they exist in both the unbound state and as complexes with intraand intermolecular hydrogen bond. Amides 1 and 2 are subjected to photolysis, which results in the formation of a triplet state and phenoxyl radicals RO? presumably due to the absorption of the second photon by the excited singlet state. The formation of radical products due to N–H bond ionization was not observed. The main channel of decay of the triplet state and radicals RO? is triplet–triplet annihilation and recombination (k _r ≈ 2.3?10⁸ L mol^–1 s^–1), respectively. The UV irradiation of compounds 1 and 2 leads to the excitation of the amide groups, and no formation of radical products due to N–H bond ionization was observed.     

Triethylantimony(V) complexes with bidentate O,N-, O,O- and tridentate O,N,O′-coordinating o-iminoquinonato/o-quinonato ligands: Synthesis, structure and some properties

The novel triethylantimony(v) o-amidophenolato (AP-R)SbEt₃ (R = i-Pr, 1; R = Me, 2) and catecholato (3,6-DBCat)SbEt₃ (3) complexes have been synthesized and characterized by IR, NMR spectroscopy (AP-R is 4,6-di-tert-butyl-N-(2,6-dialkylphenyl)-o-amidophenolate, alkyl = isopropyl (1) or methyl (2); 3,6-DBCat is 3,6-di-tert-butyl-catecholate). Complexes 1–3 have been obtained by the oxidative addition of corresponding o-iminobenzoquinones or o-benzoquinones to Et₃Sb. The addition of 4,6-di-tert-butyl-N-(3,5-di-tert-butyl-2-hydroxyphenyl)-o-iminobenzoquinone to Et₃Sb at low temperature gives hexacoordinate [(AP-AP)H]SbEt₃ (4) which decomposes slowly in vacuum with the liberation of ethane yielding pentacoordinate complex [(AP-AP)]SbEt₂ (5). [(AP-AP)H]²⁻ is O,N,O′-tridentate amino-bis-(3,5-di-tert-butyl-phenolate-2-yl) dianion and [(AP-AP)]³⁻ is amido-bis-(3,5-di-tert-butyl-phenolate-2-yl) trianion. The decomposition of 4–5 accelerates in the presence of air. o-Amidophenolates 1 and 2 bind molecular oxygen to give spiroendoperoxides Et₃Sb[L-iPr]O₂ (6) or Et₃Sb[L-Me]O₂ (7) containing trioxastibolane rings. This reaction proceeds slowly and reaches the equilibrium at 15–20% conversion five times more than for (AP-R)SbPh₃ analogues. Molecular structures of 1 and 5 were determined by X-ray analysis.     

Synthesis of (4-hydroxy-3,5-di-tert-butylphenyl)-chloromethanediphenylphosphine oxide and its reactions with aprotic nucleophilic reagents

Reaction of (4-hydroxy-3,5-di-tert-butylphenyl)chloromethanediphenylchlorophosphonium chloride with trimethyl orthoformate affords (4-hydroxy-3,5-di-tert-butylphenyl)chloromethanediphenylphosphine oxide. The latter undergoes dehydrochlorination under the action of trimethyl orthoformate and O-methyl diethylphosphinate, and with diphenylchloro- and triphenyl phosphines it gives the corresponding phosphonium salts.     

Metallkomplexe von Farbstoffen. VIII Übergangsmetallkomplexe des Curcumins und seiner Derivate

Metal Complexes of Dyes. IX. Transition Metal Complexes of Curcumin and Derivatives The bidentate monoanions of curcumin[CU, (1, 7-bis(4-hydroxy-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione)], diacetylcurcumin[DACU, (1,7-bis(4-acetyl-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione)], dihydroxycurcumin[DHCU, (1,7-bis(4-hydroxiphenyl)-hepta-1,6-diene-3,5-dione)], dimethylcurcumin [DMCU, (1,7-bis(3,4-dimethoxyphenyl)-hepta-1, 6-diene-3,5-dione)] and trimethylcurcumin[TMCU, (1,7-bis(3,4-dimethoxyphenyl)-4-methylhepta-1,6-diene-3,5-dione)] form with chloro bridged complexes [(R₃P)MCl₂]₂ (M?Pd, Pt; R?phenyl, n-butyl, ethyl, tolyl), [η⁵-C₅Me₅)MCl₂]₂ (M?Rh, Ir), [(η⁶-p-cymene)RuCl₂]₂, [(η³-C₃H₅)PdCl]₂, di-μ-chlorobis[N-(diphenylmethylene)-glycinethylester-(C,N)]-dipalladium(II) and with [(η⁵-C₅Me₅)Co(CO)I₂] monochelate dye complexes. The structure of [(η⁶-p-cymene)(Cl)Ru(DMCU)] was determined by X-ray diffraction. The dichelates (DMCU)₂M with M?Cu, Ni, (CU)₂Pd and the trichelate (CU)₃Fe were obtained. Cationic bipyridine copper(II) complexes with CU, DHCU, and DMCU were sythesized by treating the dye ligands with copper(II) acetate, 2,2′-bipyridine and ammoniumtetrafluoroborate. In comparison to the free 1.3-diketones the dye complexes show a bathochromic shift in the UV/VIS spectra.     

Potassium and sodium 2,6-di-tert-butylphenoxides and their properties

The crucial factor of the reaction of 2,6-di-tert-butylphenol with alkali hydroxides is temperature, depending on which two types of potassium or sodium 2,6-di-tert-butylphenoxides are formed. These types exhibit different catalytic activity in the alkylation of 2,6-di-tert-butylphenol with methyl acrylate. More active forms of 2,6-Bu^t ₂C₆H₃OK or 2,6-Bu^t ₂C₆H₃ONa are synthesized at temperatures higher than 160 °C and are predominantly the monomers, which dimerize on cooling. The data of ¹H NMR, electronic, and IR spectra for the corresponding forms of 2,6-Bu^t ₂C₆H₃OK and 2,6-Bu^t ₂C₆H₃ONa isolated in the individual state are in agreement with cyclohexadienone structure. In DMSO or DMF, the dimeric forms of 2,6-di-tert-butylphenoxides react with methyl acrylate to form methyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate in 64–92% yield. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2138–2143, December, 2006.     

Synthesis and characterization of copper(II) and cobalt(II) complexes with two new potentially hexadentate Schiff base ligands. X-ray crystal structure determination of one copper(II) complex

Two new potentially hexadentate N₂O₄ Schiff base ligands 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy) phenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H₂L¹] and 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy)-5-tert-butylphenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H₂L²] were prepared from the reaction of 3,5-di-tert-butyl-2-hydroxy benzaldehyde with 1,2-bis(2′-aminophenoxy)benzene or 1,2-bis(2′-aminophenoxy)-4-t-butylbenzene, respectively. From the direct reaction of ligands [H₂L¹] and [H₂L²] with copper(II) and cobalt(II) salts in methanolic solution and in the presence of N(Et)₃ the neutral [CuL¹], [CuL²], [CoL¹] and [CoL²] complexes were prepared. All complexes were characterized by IR spectra, elemental analysis, magnetic susceptibility, mass spectra, molar conductance (Λ_m), UV-Vis spectra and in the case of [CuL²] with X-ray diffraction. X-ray crystal structure of [CuL²] showed that the complex contains copper(II) in a distorted square planar environment of N₂O₂ donors. Three CH/π interactions were observed in the molecular structure of latter complex.     

Effects of solvation on charge distribution of 1,2-semiquinonato/catecholatocobalt complexes containing bis(3-pyridyl) phenylvinylsilane

Recrystallization of [Co(3,5-dbbq)₂(L)₂] (3,5-dbbq?=?3,5-di-tert-butyl-1,2-benzoquinone; L?=?bis(3-pyridyl)phenylvinylsilane) from diethyl ether at ?20?°C produces trans-[Co(3,5-dbbq)₂(L)₂] while the recrystallization from toluene at ?20?°C gives trans-[Co(3,5-dbbq)₂(L)₂]·2PhMe. The complex exists as trans-[Co^III(3,5-dbsq)(3,5-dbcat)(L)₂] (3,5-dbsq?=?3,5-di-tert-butyl-1,2-semiquinonato; 3,5-dbcat?=?3,5-di-tert-butylcatecholato) in the solid state at 173?K. Differences in charge distribution between trans-[Co(3,5-dbbq)₂(L)₂] and trans-[Co(3,5-dbbq)₂(L)₂]·2PhMe have been observed based on the effective magnetic moments and IR spectra of the complexes along with their X-ray crystal structures.     

Thermal and photoinduced valence tautomerism of a chain compound

Herein reported is an example of one-dimensional coordination polymer [CoII(3,5-DBsq)2(dpg)]·(3,5-H2DBcat)2 (1) (3,5-DBsq = 3,5-di-tert-butylsemiquinonate, 3,5-H2DBcat = 3,5-di-tert-butyl-benzene-1,2-diol, dpg = meso-alpha,beta-di(4-pyridyl)glycol) capable of undergoing thermal and photoinduced valence tautomeric transitions.     

Impact of Group 10 Metals on the Solvent-Induced Disproportionation of o-Semiquinonato Complexes

The oxidation of [M^II(3,5-DTBCat)(DTBbpy)] (M=Ni ( [Ni] ), Pd ( [Pd] ), and Pt ( [Pt] ); 3,5-DTBCat=3,5-di-tert-butylcatecholato; DTBbpy=4,4′-di-tert-butyl-2,2′-bipyridine) afforded the dimeric {[Ni^II(3,5-DTBSQ)(DTBbpy)](PF₆)}₂ ( {[Ni](PF₆)}₂ ; 3,5-DTBSQ=3,5-di-tert-butylsemiquinonato) and monomeric semiquinonato (SQ) complexes [M^II(3,5-DTBSQ)(DTBbpy)](PF₆) (M=Pd ( [Pd](PF₆) ) and Pt ( [Pt](PF₆) )). The negative solvatochromic properties of the SQ complexes allowed us to estimate the relative order of their dipole moments: [Pd](PF₆) > [Pt](PF₆) > {[Ni](PF₆)}₂ . The complexes [Pd](PF₆) and [Pt](PF₆) adopt monomeric structures and are stable in CH₂Cl₂ and toluene, whereas they gradually disproportionate at room temperature to [M] and 3,5-di-tert-butylbenzoquinone (3,5-DTBBQ) in polar solvents such as THF, MeOH, EtOH, DMF, or DMSO. The results of spectroscopic studies suggested that the oxidized nickel complex adopts a monomeric structure ( [Ni](PF₆) ) in CH₂Cl₂, but a dimeric structure ( {[Ni](PF₆)}₂ ) in the other investigated solvents. In polar solvents, {[Ni](PF₆)}₂ may disproportionate to [Ni] and 3,5-DTBBQ at 323 K, thereby demonstrating a significant solvent- and metal-dependence in temperature. The relative activities of {[Ni](PF₆)}₂ and [M](PF₆) toward disproportionation are related to the electrochemically estimated K_dis values in CH₂Cl₂ and DMF. The present work demonstrates that solvent polarity and the dipole moments of the SQ complexes promote disproportionation, which can be controlled by a judicious choice of the metal ion, solvent, and temperature.     

Dinuclear nickel(II) complexes with Schiff base ligands: syntheses, structures and bio-relevant catalytic activities

Three Ni(II) complexes of cresol-based Schiff-base ligands, namely [Ni₂(L¹)(NCS)₃(H₂O)₂], (1) [Ni₂(L²)(CH₃COO)(NCS)₂(H₂O)] (2) and [Ni₂(L³)(NCS)₃] (3), (where L¹ = 2,6-bis(N-ethylpyrrolidineiminomethyl)-4-methylphenolato, L² = 2,6-bis(N-ethylpiperidineiminomethyl)-4-methylphenolato and L³ = 2,6-bis{N-ethyl-N-(3-hydroxypropyl iminomethyl)}-4-methylphenolato), have been synthesized and structurally characterized by X-ray single-crystal diffraction in addition to routine physicochemical techniques. Density functional theory calculations have been performed to understand the nature of the electronic spectra of the complexes. Complexes 1?C3 when reacted with 4-nitrophenyl phosphate in 50:50 acetonitrile?Cwater medium promote the cleavage of the O?CP bond to form p-nitrophenol and smoothly convert 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) either in MeOH or in MeCN medium. Phosphatase- and catecholase-like activities were monitored by UV?Cvis spectrophotometry and the Michaelis?CMenten equation was applied to rationalize all the kinetic parameters. Upon treatment with urea, complexes 1 and 2 give rise to [Ni₂(L¹)(NCS)₂(NCO)(H₂O)₂] (1??) and [Ni₂(L²)(CH₃COO)(NCO)(NCS)(H₂O)] (2??) derivatives, respectively, whereas 3 remains unaltered under same reaction conditions.     

Kinetic studies of dicopper complexes in catechol oxidase model reaction by using an approximationless evaluating method

The oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butyl-o-benzoquinone catalyzed by dinuclear copper(II) complexes {[Cu₂(L¹)(CF₃SO₃)₂(H₂O)₄]-(CF₃SO₃)₂ (1) and [Cu₂(L²O)](CF₃SO₃)₂ (2)| has been investigated in methanol saturated with O₂ at ambient temperature. Detailed kinetic studies were carried out and for the treatment the fitting software ZiTa was applied. On the basis of the results in the kinetic studies a possible mechanism of the catalytic reaction is proposed.This revised version was published online in December 2005 with corrections to the Cover Date.     

Synthesis of a re(VI)-catecholato complex by air oxidation of oxorhenium(V)

The complex [Re(ddcat)₃] (H₂ddcat?=?3,5-di-tert-butylcatechol) was prepared by the reaction of either cis-[Re^VO₂I(PPh₃)₂] or (n-Bu₄N)[Re^VOCl₄] with H₂ddcat in toluene in air. X-ray structure determination of the product unequivocally illustrates that the bidentate chelates are in the catecholato rather than the semiquinone form and that the metal has a formal oxidation state of +VI.     

Synthesis,characterization, and crystal structures of cobalt(II), copper(II), and zinc(II) complexes of a bidentate iminophenol

A bidentate iminophenol (HL = 2-((4-methoxyphenylimino)methyl)-4,6-di-tert-butylphenol derived from condensation of 4-methoxyaniline and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) was mixed with divalent metal salts to form the corresponding mononuclear metal complexes [M^II(L)₂] (M = Co (1), Cu (2), and Zn (3)). The complexes are characterized by different spectroscopic and analytical tools. X-ray crystal structures of the complexes revealed homoleptic mononuclear complexes with MN₂O₂ coordination. The cobalt(II) (1) and zinc(II) (3) complexes display a pseudo-tetrahedral coordination geometry, whereas the copper(II) complex (2) exhibits a distorted square-planar coordination. The zinc(II) complex (3) emits at 460 nm with a twofold enhancement of emission with respect to the free iminophenol.     

含不同芳香取代基的肼基二硫代甲酸甲酯-Ga~(3+)配合物的合成及抑菌活性

设计合成了4种含不同芳香取代基团的肼基二硫代甲酸甲酯配体(2-乙酰基吡啶肼基二硫代甲酸甲酯(L1-H)、2-甲酰基吡啶肼基二硫代甲酸甲酯(L2-H)、2-甲酰基噻吩肼基二硫代甲酸甲酯(L3-H)、2-甲酰基水杨醛肼基二硫代甲酸甲酯(L4-H))的镓配合物,对它们的抑菌活性进行了测试,并讨论了配体分子中不同芳香取代基对配合物抑菌活性的影响。在模拟生理条件下,L-H与Ga3+生成较稳定的单核配合物[Ga(L1)2]NO3(1)、[Ga(L2)2]NO3(2)、[Ga(L3)2]NO3(3)、[Ga(L4)2]NO3(4),各配合物对金黄色葡萄球菌和大肠杆菌表现出比Ga(NO3)3·9H2O强的抑制活性,抑制金黄色葡萄球菌的能力高于大肠杆菌,其中,1和2的活性比相应配体高,其余2个配合物与其配体之间无明显活性差异。L1-H和L2-H分子中吡啶基的较强吸电子效应可能是1和2具有较强抑菌活性的主要原因。4种配合物抑制黑曲霉生长的活性同样高于Ga(NO3)3·9H2O,其中3最强,并显著高于L3-H,其余配合物与相应配体间无活性差异。     

Supramolecular Architecture and a New Mode of Pyrazolate Coordination (η3) in the First Homoleptic Lanthanide Pyrazolate Complexes

A linear supramoleculecular array of anions and cations is present in the solvent-free potassium salt of the homoleptic erbium pyrazolate complex [K{Er(η²-tBu₂pz)₄}_n] ( 1 ). Treatment of 1 with [18]crown-6 in toluene/dimethoxyethane leads to formation of a charge-separated salt [Eq. (a)] in which the methyl group of a toluene molecule interacts with the potassium ion. tBu₂pz=3,5-di-tert-butylpyrazolate.     

Reactions of [(3,5-Di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-oxocyclohexa-2,5-dien- 1-ylidene)methyl]phosphonates with Phenols

Dialkyl [(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]phosphonates reacted with phenol and benzenediols in the presence of trifluoromethanesulfonic acid to give products of electrophilic substitution in the benzene ring, the corresponding diarylmethylphosphonates or [phenylenebis(arylmethylene)]- diphosphonates. The reaction of diphenyl [(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]phosphonate with 2-methylbenzene-1,3-diol at a ratio of 1: 1 afforded 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-6-hydroxy-7-methyl-2-phenoxy-2,3-dihydro-1,2λ⁵-benzoxaphosphol-6-one.     

Nuclearity Control in Molecular Copper Phosphates Derived from a Bulky Arylphosphate: Synthesis,Structural and Magnetic Studies

Starting from sterically encumbered 2,6-di-tert-butylphenyl phosphate (dtbppH₂) and co-ligand 3,5-dimethyl pyrazole (dmpz), it is possible to isolate either mono-, di- or tetranuclear copper phosphates by varying the copper source and making attendant changes in the reaction conditions. For example, reaction of copper nitrate with dtbppH₂ and dmpz at 60 °C leads to the isolation of the mononuclear copper phosphate [Cu(dtbppH)₂(dmpz)(MeOH)₂] ( 1 ) as the only product. However, the use of copper acetate in place of copper nitrate and conducting the reaction at the room temperature leads to the formation of both dinuclear [Cu(dtbpp)(dmpz)₂]₂ ( 2 ) and tetranuclear [Cu₂(dtbpp)(dmpz)₂(OAc)(MeO)]₂ ( 3 ) from the same reaction mixture. Compounds 2 and 3 could be isolated in pure form through fractional crystallization. Copper phosphates 1 – 3 have been characterized by both analytical and spectroscopic methods including EPR and magnetic measurements. The molecular structures of all three compounds were established through single crystal diffraction studies. Dc magnetic measurements indicate antiferromagnetic interactions between the metal centres in all the compounds.