A boron-boron linked large metallacarborane cluster: Characterization and X-ray structure of 8,9′-[closo-{3-Co(η-C5H5)-1,2-C2B9H10}]2

The 8,9′-[closo-{3-Co(η⁵-C₅H₅)-1,2-C₂B₉H₁₀}]₂ (1) species, in which two large closo-CoC₂B₉ sub-clusters are connected by a B-B bond, is unexpectedly obtained from the reaction of closo-[3-Co(η⁵-C₅H₅)-1,2-C₂B₉H₁₁] with sulfur in the presence of aluminium chloride under reflux conditions. The solid state conformation of 1 seems to be the result of a pair of intramolecular C-H?H-B dihydrogen bonds between the protonic H atoms of the C₅H₅ fragment of a sub-cluster and the hydridic H atoms of the C₂B₉H₁₁ fragment in the other sub-cluster in 1.     

Synthesis, properties and structures of methyldiphenylphosphonium 1-indenylide, 1-C9H6PMePh2, and its chiral tricarbonylchromium(0) complex Cr(η-1-C9H6PMePh2)(CO)3

The hitherto unknown indenyl-derived ylide, methyldiphenylphosphonium 1-indenylide, 1-C₉H₆PMePh₂ (1) and its chromium(0) complex, Cr(η⁵-1-C₉H₆PMePh₂)(CO)₃ (2) have been synthesized and characterized spectroscopically and crystallographically. The structures and properties of 1 and 2 are compared with those of the analogous C₅H₄PMePh₂ and its chromium complex, Cr(η⁵-C₅H₄PMePh₂)(CO)₃. Compound 2, obtained as a racemic mixture, exhibits planar chirality resulting from coordination of the prochiral aromatic ligand.     

Structures of cationic metallacarborane complexes [(η-9-Me2S-7,8-C2B9H10)Ni(μ-Cp)Ni(η-9-Me2S-7,8-C2B9H10)]+ and [Cp*Ru(Me2S-C2B9H10)RuCp*]+

The structures of the metallacarborane cations [(-9-Me₂S-7,8-C₂B₉H₁₀)Ni(-Cp)Ni(-9-Me₂S-7,8-C₂B₉H₁₀)]⁺ (2) and [Cp*Ru(Me₂S-C₂B₉H₁₀)RuCp*]⁺ (4b) were established by X-ray diffraction analysis. These results confirmed the triple-decker structure proposed for complex 2 earlier, whereas complex 4b proved to be 13-vertex dimetallacarborane rather than the triple-decker complex, as has been suggested earlier.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1879–1883, September, 2004.     

Nonsymmetrical iron bis(carborane) complexes (η-1-ButNH-1,7,9-C3B8H10)Fe(η-9-L-7,8-C2B9H10) (L = SMe2, NMe3)

Visible light irradiation of the benzene complex [(η-1-Bu^tNH-1,7,9-C₃B₈H₁₀)Fe(η-C₆H₆)]⁺ in the presence of the charge-compensated carborane anions [9-L-7,8-C₂B₉H₁₀]⁻ (L = SMe₂, NMe₃) affords ferracarboranes (η-1-Bu^tNH-1,7,9-C₃B₈H₁₀)Fe(η-9-L-7,8-C₂B₉H₁₀). Their structures were established by X-ray diffraction analysis.     

Cyclopentadienyl chromium and tungsten complexes with halide, methyl and σ-phenylethynyl ligands: Structures of (η-C5H5)Cr(NO)2(-CC-C6H5), (η-C5H5)Cr(NO)2I and [(η-C5H4)-COOCH3]W(CO)3Cl

With copper(I) iodide as catalyst, σ-alkynyls, compounds (η⁵-C₅H₅)Cr(NO)₂(CC-C₆H₅) (5), [(η⁵-C₅H₄)-COOCH₃]Cr(NO)₂(CC-C₆H₅) (10), and [(η⁵-C₅H₄)-COOCH₃]W(CO)₃(CC-C₆H₅) (13), were prepared from their corresponding metal chloride 1, 6 and 12. Structures of compound 3, 5 and 12 have been solved by X-ray diffraction studies. In the case of 5, there is an internal mirror plane passing through the phenylethynyl ligand and bisecting the Cp ring. The phenyl group is oriented perpendicularly to the Cp with an eclipsed conformation. The twist angle is 0° and 118.4° for -CC-Ph and two NO ligands, respectively. The orientation is rationalized in terms of orbital overlap between ψ₃ of Cp, dπ of Cr atom, and π^∗ of alkynyl ligand, and complemented by molecular orbital calculation. The opposite correlation was observed on the chemical shift assignments of C(2)-C(5) on Cp ring in compounds 6 and 12, using HetCOR NMR spectroscopy. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of ¹³C NMR data and compared with the calculations via density functional B3LYP correlation-exchange method.     

Unsaturation in binuclear cyclopentadienylchromium carbonyl thiocarbonyls: Viability of (η-C5H5)2Cr2(CS)2(CO)3 in contrast to (η-C5H5)2Cr2(CO)5

The cyclopentadienylchromium carbonyl thiocarbonyls Cp₂Cr₂(CS)₂(CO)_n (n = 4, 3, 2, 1) have been studied by density functional theory using the B3LYP and BP86 functionals. The lowest energy Cp₂Cr₂(CS)₂(CO)₄ structure can be derived from the experimentally characterized unbridged Cp₂Cr₂(CO)₆ structure by replacing the two terminal carbonyl groups furthest from the Cr-Cr bond with two terminal CS groups. The two lowest energy Cp₂Cr₂(CS)₂(CO)₃ structures have a single four-electron donor η²-μ-CS group and a formal Cr-Cr single bond of length ∼3.1 Å. In contrast to the carbonyl analogue Cp₂Cr₂(CO)₅ these Cp₂Cr₂(CS)₂(CO)₃ structures are viable with respect to disproportionation into Cp₂Cr₂(CS)₂(CO)₄ and Cp₂Cr₂(CS)₂(CO)₂ and thus are promising synthetic targets. The lowest energy Cp₂Cr₂(CS)₂(CO)₂ structures have all two-electron donor CO and CS groups and short CrCr distances around ∼2.3 Å suggesting the formal triple bonds required to give the chromium atoms the favored 18-electron configurations. These Cp₂Cr₂(CS)₂(CO)₂ structures are closely related to the known structure for Cp₂Cr₂(CO)₄. In addition, several doubly bridged structures with four-electron donor η²-μ-CS bridges are found for Cp₂Cr₂(CS)₂(CO)₂ at higher energies. The global minimum Cp₂Cr₂(CS)₂(CO) structure is a triply bridged triplet with a CrCr triple bond (2.299 Å by BP86). A higher energy singlet Cp₂Cr₂(CS)₂(CO) structure has a shorter Cr-Cr distance of 2.197 Å (BP86) suggesting the formal quadruple bond required to give each chromium atom the favored 18-electron configuration.     

Molecular Packing in the Crystal Structures of Mixed-Ligand Complexes [ZnPhen{(i-C4H9)2PS2}2] and [Zn(2,2′-Bipy){(i-C4H9)2PS2}2]

Volatile mixed-ligand complexes of Zn(i-Bu₂PS₂)₂ with Phen and 2,2-Bipy have been synthesized. The crystal structures of the complexes ZnPhen{(i-C₄H₉)₂PS₂}₂ and Zn(2,2-Bipy){(i-C₄H₉)₂PS₂}₂ were determined by single crystal X-ray diffractometry (CAD-4 diffractometer, MoK radiation, 2100 F_hkl, R = 0.0423 for the first complex and 2003 F_hkl, R = 0.0486 for the second). The crystals are monoclinic with cell dimensions a = 17.580(4), b = 9.969(2), c = 19.175(4) , = 90.33(3)°, V = 3360(1) ³, Z = 4, d _calc = 1.313 g/cm³, space group P2/n (for the Phen complex); a = 24.219(5), b = 11.386(2), c = 24.916(5) , = 97.70(3)°, V = 6809(2) ³, Z = 8, d _calc = 1.249 g/cm³, space group C2/c (for the 2,2-Bipy complex). The complexes are constructed from discrete monomer molecules. The coordination polyhedra of the Zn atoms are distorted tetrahedra formed by two S atoms of the two monodentate i-Bu₂PS ₂ ^- ligands and two N atoms of the cyclic bidentate Phen or 2,2-Bipy molecules. Intermolecular interactions and packings in the structures are analyzed.     

Effect of high external pressures on the vibrational spectra of Zeise’s complexes, K[Pt(η-C2H4)Cl3] and [Pt(η-C2H4)Cl2]2

The pressure dependences (dν/dP) of the main IR and Raman bands of Zeise’s complexes, K[Pt(η²-C₂H₄)Cl₃] and [Pt(η²-C₂H₄)Cl₂]₂, have been determined for the first time for selected pressures up to ∼33 kbar with the aid of diamond-anvil cells. Neither complex undergoes a pressure-induced structural change throughout the pressure range investigated. The dν/dP values range from −0.13 to 0.79 cm⁻¹ kbar⁻¹. The negative values have proved particularly informative in identifying the location of the CC stretching modes of the Pt-ethylene groups, a topic of considerable disagreement in the literature.     

Mixed-ligand complex compounds [Pb(Phen)×{(iso-C4H9)2PS2}2] and [Pb(2,2′-Bipy){(iso-C4H9)2PS2}2] and formation of supramolecular assemblies in their crystal structures

Mixed-ligand complex compounds [Pb(Phen)(i-Bu₂PS₂)]₂ (I) and [Pb(2,2′-Bipy)(i-Bu₂PS₂)]₂ (II) were synthesized. Their structures were determined from X-ray diffraction data (X8 APEX diffractometer, MoK _α radiation, 6392 _Fhkl , R = 0.0233 for I and 3937 F _hkl , R = 0.0252 for II). Crystals I are triclinic: a = 10.2662(3) Å, b = 12.3037(2) Å, c = 14.8444(4) Å; α = 92.054(1)°, β = 103.473(1)°, γ = 105.561(1)°, V = 1746.89(8) ų, Z = 2, ρ_calc = 1.532 g/cm³, space group P . Crystals II are monoclinic: a = 9.3462(3) Å, b = 26.3310(12) Å, c = 28.5345(13) Å; β = 96.436(1)°, V = 6977.9(5) ų, Z = 8, ρ_calc = 1.489 g/cm³, space group P2₁/n. The structures are built from mononuclear molecules. In both structures, the intermolecular contacts between the Pb and S atoms of the neighboring mononuclear molecules form supramolecular assemblies involving two molecules. The environment of the Pb atoms in the assemblies is a pentagonal bipyramid, N₂S₄₊₁. The assemblies are joined into ribbons by π-π interactions of the Phen rings in I and C…C short contacts between the pyridine rings in II. Original Russian Text Copyright ? 2008 by R. F. Klevtsova, E. A. Sankova, T. E. Kokina, L. A. Glinskaya, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 1, pp. 123–131, January–February, 2008.     

Low-temperature X-ray diffraction study of [CuII(1,10-C12H8N2)3]2+{CoIII[η5-(3)-1,2-C2B9H11]2} 2? ·CH3CN

Single crystal XRD is used to study the crystal structure of a new compound containing the dicarbollyl cluster anion Co(III) with the composition [CuPhen₃][Co(C₂B₉H₁₁)₂]₂·CH₃CN, where Phen is 1,10-phenanthroline. The crystallographic data: C₄₆H₇₁B₃₆N₇Co₂Cu, M = 1292.66, monoclinic system, P2₁/c space group, unit cell parameters a = 14.7178(2) ?, b = 19.5640(4) ?, c = 22.8663(5) ?, β = 106.6601(7)°, V = 6307.75(33) ?³, Z = 4, d _x = 1.361 g/cm³, T = 100 K, μ = 0.90 mm⁻¹. The structure is solved by the direct method and refined by the full-matrix LSM in an anisotropic-isotropic (for H atoms) approximation up to the final agreement factors R ₁ = 0.0370, wR ₂ = 0.0869 for 13,807 I _hkl ≥ 2 σ _I out of 18,295 measured I _hkl . The structure consists of [CuPhen₃] cations, Co(C₂B₉H₁₁)₂ anions, and acetonitrile molecules MeCN. The central Cu atom in the cation in the general position, and its coordination geometry is a distorted extended octahedron formed by six nitrogen atoms of the three bidentate Phen ligands. The coordination of Cu(II) in the cation is (2+2+2) with two long axial and four shorter equatorial Cu-N bonds, whose average lengths are 2.239(2) ? and 2.077(1) ? respectively. Each anion has its own position of the -C₂-groups; for Co(1), it is a quasi-gauche-configuration; for Co(2), a quasi-trans-configuration.     

Functionalised tetraarylstannanes Sn[C6H4-R]4 (R=-CH(CH2O)2, -CHO, -COOH, -CHN-NH-C6H3-2,4-(NO2)2, -CH2OH, -CO-NH-CH2-COO-CH3, -CH[N(C2H4)2O]2)

Reaction of tin tetrachloride with the appropriate Grignard reagent gave Sn[C₆H₄-CH(OCH₂)₂]₄ (2), which was transformed to Sn[C₆H₄-CHO]₄ (3) and its hydrazido and amino derivatives Sn[C₆H₄-CHN-NH-C₆H₃-2,4-(NO₂)₂]₄ (5) and Sn{C₆H₄-CH[N(C₂H₄)₂O]₂}₄ (8). Oxidation of (3) produced Sn[C₆H₄-COOH]₄ (4) while reduction of (3) gave Sn[C₆H₄-CH₂-OH]₄ (6). From the acid 4, an amino acid Sn[C₆H₄-CO-NH-CH₂-CO-OCH₃]₄ (7) could be obtained by reaction with the methyl ester of glycine. All compounds were isolated in pure form with yields of 40-64% and were characterised by spectroscopic means (heteronuclear NMR) or by X-ray structure determination (3).     

Alternative syntheses and X-ray diffraction analyses of the parent tricarbaborane compounds [nido-7,8,9-C3B8H11], [nido-7,8,10-C3B8H11] and [1-(η-C5H5)-closo-1,2,4,10-FeC3B8H11]

Reaction of the neutral tricarbaborane nido-7,8,9-C₃B₈H₁₂ (1) with triethylamine in CH₂Cl₂ led to quantitative deprotonation and isolation of the corresponding Et₃NH⁺ salt of the [nido-7,8,9-C₃B₈H₁₁]⁻ anion (2). This was converted into PSH⁺ and Me₄N⁺ salts via metathetic cation exchange. Heating of the solid Me₄N⁺[7,8,9-C₃B₈H₁₁]⁻ in mineral oil at 350 °C for 2 h resulted in thermal rearrangement and isolation of the cage isomeric compound Me₄N⁺[7,8,10-C₃B₈H₁₁]⁻. Finally, compound 1 was directly complexed via reaction with [CpFe(CO)₂]₂ (Cp = η⁵-C₅H₅) to generate the ferratricarbollide sandwich [1-Cp-closo-1,2,4,10-FeC₃B₈H₁₁] (4) in 60% yield. The structures of all the generic compounds of tricarbollide chemistry, 1 (PSH⁺ salt), 2 (MePPh₃⁺salt), and 4, were established unambiguously by an X-ray diffraction analysis.     

Synthesis and structures of the silyl bridged bis(indenyl) diruthenium complexes and a novel indenyl nonanuclear ruthenium cluster Ru9(μ6-C)(CO)14(μ3-η:η:η-C9H7)2

Thermal treatment of C₉H₇SiMe₂C₉H₇ and C₉H₇Me₂SiOSiMe₂C₉H₇ with Ru₃(CO)₁₂ in refluxing xylene gave the corresponding diruthenium complexes (E)[(η⁵-C₉H₆)Ru(CO)]₂(μ-CO)₂ [E = Me₂Si (1), Me₂SiOSiMe₂ (2)]. A desilylation product [(η⁵-C₉H₇)Ru(CO)]₂(μ-CO)₂ (3) was also obtained in the latter case. Similar treatment of C₉H₇Me₂SiSiMe₂C₉H₇ with Ru₃(CO)₁₂ gave a novel indenyl nonanuclear ruthenium cluster Ru₉(μ₆-C)(CO)₁₄(μ₃-η⁵:η²:η²-C₉H₇)₂ (5) with carbon-centered tricapped trigonal prism geometry, in addition to the diruthenium complex (Me₂SiSiMe₂)[(η⁵-C₉H₆)Ru(CO)]₂(μ-CO)₂ (4) and the desilylation product 3. Complex 4 can undergo a thermal rearrangement to form the product [(Me₂Si)(η⁵-C₉H₆)Ru(CO)₂]₂ (6). The molecular structures of 1, 2, 4, 5, and 6 were determined by X-ray diffraction.     

Synthesis and crystal structure of highly soluble ansa-titano- and zirconocene dichloride complexes [Me2Si(η-C5H2(SiMe3)2]2MCl2 (M=Ti, Zr)

The synthesis and X-ray characterization of ansa-metallocene dichloride titanium and zirconium complexes of the type [Me₂Si(η⁵-C₅H₂(SiMe₃)₂)₂]MCl₂ (M=Zr (1), Ti (2)) are reported. The complexes have been tested for ethylene polymerization.     

Synthesis and reactions of cycloheptadienyl and cyclooctadienyl tungsten complexes: X-ray crystal structure of [W(CO)2(PPh3)2(η-C7H9)][BF4]

Protonation of the cycloheptatriene complex [W(CO)₃(η⁶-C₇H₈)] with H[BF₄] · Et₂O in CH₂Cl₂ affords the cycloheptadienyl system [W(CO)₃(η⁵-C₇H₉)][BF₄] (1). Complex 1 reacts with NaI to yield [WI(CO)₃(η⁵-C₇H₉)], which is a precursor to [W(CO)₂(NCMe)₃(η³-C₇H₉)][BF₄], albeit in very low yield. The dicarbonyl derivatives [W(CO)₂L₂(η⁵-C₇H₉)]⁺ (L₂=2PPh₃, 4, or dppm, 5) were obtained, respectively, by H[BF₄] · Et₂O protonation of [W(CO)₂(PPh₃)(η⁶-C₇H₈)] in the presence of PPh₃ and reaction of 1 with dppm. The X-ray crystal structure of 4 (as a 1/2 CH₂Cl₂ solvate) reveals that the two PPh₃ ligands are mutually trans and are located beneath the central dienyl carbon and the centre of the edge bridge. The first examples of cyclooctadienyl tungsten complexes [WBr(CO)₂(NCMe)₂(1-3-η:5,6-C₈H₁₁)] (6) and [WBr(CO)₂(NCMe)₂(1-3-η:4,5-C₈H₁₁)] (7) were synthesised by reaction of [W(CO)₃(NCR)₃] (R=Me or Prⁿ) with 3-Br-1,5-cod/6-Br-1,4-cod or 5-Br-1,3-cod/3-Br-1,4-cod (cod=cyclooctadiene), respectively. Complexes 6 and 7 are precursors to the pentahapto-bonded cyclooctadienyl tungsten species [W(CO)₂(dppm)(1-3:5,6-η-C₈H₁₁)][BF₄] and [W(CO)₂(dppe)(1-5-η-C₈H₁₁)][BF₄] · CH₂Cl₂.     

Synthesis of (C8H11N)2·Zn(OAc)2, (C8H11N)2·Cu(OAc)2, and (C8H11N)2·CuCl2 complexes and application to the Henry reaction

(C₈H₁₁N)₂·Zn(OAc)₂ (1a), (C₈H₁₁N)₂·Cu(OAc)₂ (1b), and (C₈H₁₁N)₂·CuCl₂ complexes are synthesized by a simple one-pot method. The crystal structures of 1a, 1b, and 1c are determined by X-ray crystallography. The complexes are also characterized by NMR, IR, MS, and elemental analysis and used as the catalysts applied to the Henry reaction; moderate to high yields are obtained at room temperature.     

Synthesis, structure, and thermal decomposition of [H2(4,4′-Bipy)][In(H2O)2(NCS)4]2 and [HUr]2[In(H2O)(NCS)5] · 2H2O

The reaction of indium thiocyanate with bipyridine (4,4-Bipy) and urotropine (Ur) gave [H₂(4,4′-Bipy)][In(H₂O)₂(NCS)₄]₂ (I) and [HUr]₂[In(H₂O)(NCS)₅] · 2H₂O (II), which were identified using elemental analysis, IR spectra, and thermogravimetric analysis. The thermal decomposition of compound I and II ends at 650 and 640°C, respectively, and gives In₂O₃. X-Ray diffraction analysis of compound I showed that complex anions in the crystal form chains through O-H…S hydrogen bonds. The anion chains form a close packing of columns with bipyridine cations located in the voids. Original Russian Text ? S.P. Petrosyants, A.B. Ilyukhin, V.A. Ketsko, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 6, pp. 951–955.     

两个含有平行交替链的新型二氰胺配位高聚物: {Mn(dmpz)[N(CN)2]2}2和{Cu(dmpz)[N(CN)2]2}2

Two new dicyanamide coordination polymers, {Mn(dmpz)[N(CN)2]2}2 (1) and {Cu(dmpz)[N(CN)2]2}2 (2)(dmpz=3,5-dimethylpyrazole), were synthesized and characterized by single crystal X-ray diffraction analysis and IR spectroscopy. In 1 and 2 the metal ions have two different coordination modes, where one is coordinated to four dicyanamide anions and two monodentate dmpz molecules to form a slightly distorted octahedral geometry, while the other adopts octahedral geometry, surrounded by four nitrile N atoms and two amide N atoms of the dicyanamide anions. Both complexes contain two alternating chains that are parallel to each other.     

Crystal structures of mixed-ligand complexes [CoPhen{(i-C4H9)2PS2}2], [Co(2,2′-Bipy){(i-C4H9)2PS2}2] and the development of dimer assemblies in them

X-ray diffraction data have been used to determine crystal structures of coordination compounds [CoPhen{ (i-C₄H₉)₂PS₂}₂] (I) and [Co(2,2′-Bipy){ (i-C₄H₉)₂PS₂}₂] (II) (X8-APEX diffractometer, MoK _α∔ -radiation, 3083 F _hkl , R = 0.0647 for I and 5381 F _hkl , R = 0.0597 for II). I is triclinic, a = 11.244(1) Å, b = 14.892(2) Å, c = 21.419(4) Å, α = 71.867(4)°, β = 81.553(4)°, γ = 76.777(4)°, V = 3306,9(8) ų; Z = 4, ρ_calc = 1.321 g/cm³, space group ; II is monoclinic, a = 14.693(2) Å; b = 20.868(3) Å, c = 11.417(1) Å; β = 106.46(5)°; V = 3357.1(7) ų, Z = 4, ρ_calc = 1.254 g/cm³, space group P2₁/c. The structures are built from discrete mononuclear molecules. Coordination polyhedra of Co atoms are distorted octahedra formed by four S atoms of two bi-dentate chelating ligands (i-C₄H₉)₂PS ₂ ⁻ and two N atoms of two bi-dentate chelating Phen or 2,2′-Bipy molecules. The interaction of the molecules in the structures of I and II has been analyzed. It has been found that the molecules of I and II form dimer ensembles owing to π-π-interactions of Phen or 2,2′-Bipy. Original Russian Text Copyright ? 2005 by R. F. Klevtzova, L. A. Glinskaya, T. E. Kokina, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 4, pp.705–714, July–August, 2005.     

Synthesis and molecular structure of [Re2(μ:η-C24H18N4)(CO)6] containing the rtct-tetrakis(2-pyridyl)cyclobutandiyl ligand, derived from the reaction of [Re2(CO)8(MeCN)2] and 1,2-bis(2-pyridyl)ethene

The reaction of the labile compound [Re₂(CO)₈(CH₃CN)₂] with trans-1,2-bis(2-pyridyl)ethene (C₁₂H₁₀N₂) at room temperature in tetrahydrofuran affords the compounds [Re₂(μ:η³-C₁₂H₁₀N₂)(CO)₈] (1) and the oxidative addition product [Re₂(μ-H)(μ:η³-C₁₂H₉N₂)(CO)₇] (2). When the reaction is carried out at temperatures of refluxing tetrahydrofuran, besides compounds 1 and 2, the oxidative addition product [Re₂(μ-H)(μ:η⁴-C₁₂H₉N₂)(CO)₆] (3), the insertion product [Re₂(μ:η⁴-C₁₂H₁₀N₂)(CO)₈] (4) and [Re₂(μ:η⁶-C₂₄H₁₈N₄)(CO)₆] (5) are obtained. Compound 5 contains the organic ligand rtct-tetrakis(2-pyridyl)cyclobutandiyl which is derived from a [2 + 2] cycloaddition of 1,2-bis(2-pyridyl)ethene mediated by its coordination to the bimetallic framework. The molecular structures of 1, 2, 4 and 5 were confirmed by X-ray crystallographic studies.