The structurally characterised silyl complexes, Os(κ-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 and Os(κ-S2CNMe2)(SiCl3)(CO)(PPh3)2, which have remarkably unreactive Si-Cl bonds

Treatment of Os(κ²-S₂CNMe₂)H(CO)(PPh₃)₂ with HSiMeCl₂ or HSiCl₃ gives in high yield Os(κ²-S₂CNMe₂)(SiMeCl₂)(CO)(PPh₃)₂ (1) or Os(κ²-S₂CNMe₂)(SiCl₃)(CO)(PPh₃)₂ (2), respectively. The crystal structures of both compounds have been determined and the Os-Si distances are 2.3672(10) Å for 1 and 2.3449(12) Å for 2. In solution, and under forcing conditions, both compounds are extraordinarily unreactive towards hydroxide ions.     

Thiolate-bridged heterometallic complexes of manganese and platinum: Synthesis and molecular structures of (CO)4Mn(μ-SPh)Pt(PPh3)2, (CO)3(PPh3)Mn(μ-SPh)Pt(PPh3)(CO), and (CO)3Mn(μ-SPh)Pt(PPh3)(Dppm)

A reaction of the dimer [Mn(CO)₄(SPh)]₂ with (PPh₃)₂Pt(C₂Ph₂) gave the heterometallic complex (CO)₄Mn(μ-SPh)Pt(PPh₃)₂ (I) and its isomer (CO)₃(PPh₃)Mn(μ-SPh)Pt(PPh₃)(CO) (II). A reaction of complex I with a diphosphine ligand (Dppm) yielded the heterometallic complex (CO)₃Mn(μ-SPh)Pt(PPh₃)(Dppm) (III). Complexes I–III were characterized by X-ray diffraction. In complex I, the single Mn-Pt bond (2.6946(3) ?) is supplemented with a thiolate bridge with the shortened Pt-S and Mn-S bonds (2.3129(5) and 2.2900(6) ?, respectively). Unlike complex I, in complex II, one phosphine group at the Pt atom is exchanged for one CO group at the Mn atom. The Mn-Pt bond (2.633(1) ?) and the thiolate bridge (Pt-S, 2.332(2) ?; Mn-S, 2.291(2) ?) are retained. In complex III, the Mn-Pt bond (2.623(1) ?) is supplemented with thiolate (Pt-S, 2.341(2) ?; Mn-S, 2.292(2) 0?) and Dppm bridges (Pt-P, 2.240(1)?; Mn-P, 2.245(2) ?). Apparently, the Pt atom in complexes I–III is attached to the formally double bond , as in Pt complexes with olefins.     

Stable radical adducts of diisopropylphosphoryl radicals with fullerene complexes (η2-C60)Os(CO)(PPh3)2(CNBut) and (η2-C70)Os(CO)(PPh3)2(CNBut)

It was determined by ESR spectroscopy that the UV irradiation of toluene solutions containing Hg[P(O)(OPrⁱ)₂ and the complex (²-C₆₀)Os(CO)(PPh₃)₂(CNBu^t) produces six stable regioisomeric adducts of phosphoryl radicals with complexes, which are not demetallated under UV irradiation and do not dimerize in the absence of UV irradiation. This is caused by the addition of the phosphoryl radicals to the carbon atoms of fullerene localized near the metal-containing moiety. The addition of the phosphoryl radicals to (²-C₇₀)Os(CO)(PPh₃)₂(CNBu^t) gives rise to the formation of nine stable regioisomeric radical adducts. A comparison of the composition of regioisomers of the radical adducts of C₇₀ with the phosphoryl radicals, which were formed directly from C₇₀ and from the radical adducts of ²-C₇₀)Os(CO)(PPh₃)₂(CNBu^t) by the demetallation of the latter, revealed an orienting effect of the osmium-containing moiety on the addition of the phosphoryl radicals to the fullerene complex.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1968–1972, September, 2004.     

[Cu(HIm)2(PPh3)2](BF4)的合成与晶体结构

A Cu(Ⅰ) complex with mix ligands [Cu(HIm)₂(PPh₃)₂](BF₄) was synthesized and characterized by elemental analysis, IRspectroscopy and X-ray diffraction crystallography. The crystal belongs to monoclinic system and P2₁/c space group, with cell parameters, a=1.2836(3)nm, b=1.5089(3)nm, c=2.0661(4)nm, α=90°, β=101.464(4)°,γ=90°, V=3.9219(13)nm³, Z=4 and D_c=1.374mg·m^-3. The Cu(Ⅰ) is coordinated by two Patoms from triphenylphosphine and two Natoms from imidazole to form the distorted tetrahedral geometry.     

对苯二甲酸二丙炔醇酯与Co2(CO)8、Mo2Cp2(CO)4和RuCo2(CO)11的反应

室温下对苯二甲酸二丙炔醇酯分别与Co2CO8Mo2Cp2CO4和RuCo2CO11反应得到三个有机金属化合物C6H4pCO2CH2C2Hμ2Co2CO621、C6H4pCO2CH2C2H2RuCo2CO922和HC2CH2OCOC6H4pCO2CH2C2HμMo2Cp2CO43。研究发现三种金属核对端炔氢的屏蔽作用依次为RuCo2CO9>Co2CO6>Mo2CO4Cp2。化合物1的晶体衍射发现属三斜晶系空间群a=8.1392b=8.8083c=11.3433β=96.2606°V=773.443Z=1Dc=1.748g·cm-3R=0.0513wR=0.1266。     

Some complexes containing Pt-C5-Co3 fragments: Molecular structure of trans-Pt{CCCC-μ3-C[Co3(μ-dppm)(CO)6(PPh3)]}2(PPh3)2 determined using synchrotron radiation

Reactions of platinum(II) chloro-phosphine complexes with Co₃(μ₃-CCCCCSiMe₃)(μ-dppm)(CO)₇ in the presence of NaOMe have given the compounds Pt{CCCC-μ₃-C[Co₃(μ-dppm)(CO)₇]}₂(dppe) (1), trans-Pt{CCCC-μ₃-C[Co₃(μ-dppm)(CO)₇]}₂(PEt₃)₂ (2) and trans-Pt{CCCC-μ₃-C[Co₃(μ-dppm) (CO)₆(PPh₃)]}₂(PPh₃)₂ (3), each of which contains two Co₃ clusters linked by C₅ chains to the Pt centre. Electrochemical studies (CVs) show the presence of both oxidation and reduction processes, the latter probably occurring on the CCo₃ cores. Ready reductive elimination of {Co₃(μ-dppm)(CO)₇}₂(μ₃:μ₃-C₁₀) occurs from 1 upon heating. The X-ray study of 3 was carried out using synchrotron radiation (Advanced Photon Source, Argonne, IL) to confirm its structure.     

Pyridine-2-thione (pySH) derivatives of silver(I): Synthesis and crystal structures of dinuclear [Ag2Cl2(μ-S-pySH)2(PPh3)2] and [Ag2Br2(μ-S-pySH)2(PPh3)2] complexes

Reaction of silver(I) halides with PPh₃ in acetonitrile and then with pyridine-2-thione (pySH) chloroform (1:1:1 molar ratio) has yielded sulfur bridged dimers of general formula, [Ag₂X₂(μ-S-pySH)₂(PPh₃)₂] (X = Cl, 1, Br, 2). Both these complexes have been characterized using analytical data, NMR spectroscopy and single crystal X-crystallography. The central Ag₂S₂ cores form parallelograms with unequal Ag–S bond distances (2.5832(8), 2.7208(11) Å) in 1 and (2.6306(4), 2.6950(7) Å) in 2, respectively. The Ag?Ag contacts of compounds 1 and 2 are 3.8425(8) and 3.8211(4) Å, respectively. The angles around Ag (in the range 87.19(2)–121.71(2)° in 1 and 87.81(2)–121.53(2)° in 2) reveal highly distorted tetrahedral geometry. There are inter dimer π–π stacking interactions between pyridyl rings (inter ring distances of 3.498 and 3.510 Å in complexes 1 and 2, respectively). The solution state ³¹P NMR spectroscopy has shown the existence of both monomers and dimers. The studies reveal relatively weaker intramolecular –NH?Cl hydrogen bonding in case of AgCl vis-à-vis that in CuCl which favored both a monomer and a dimer with AgCl, and only a monomer with CuCl.     

CO substitution in HRu3(CO)10(μ-COMe) by the unsaturated diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd): Synthesis and reactivity studies of the face-capped cluster Ru3(CO)7(μ3-COMe)[μ-P(Ph)CC(PPh2)C(O)CH2C(O)]

The reaction of the methylidyne-bridged cluster HRu₃(CO)₁₀(μ-COMe) (1) with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and Me₃NO furnishes HRu₃(CO)₈(μ-COMe)(bpcd) (2) and HRu₃(CO)₈(Ph₂PH)[μ-PPh₂CCC(O)CH₂C(O)] (3) as the major and minor products, respectively. The ¹H and ³¹P NMR data indicate that the bpcd ligand in 2 is chelated to one of the ruthenium atoms that is bridged by the hydride and methylidyne ligands. Thermolysis of 2 is accompanied by P-Ph bond cleavage and elimination of benzene to yield Ru₃(CO)₇(μ₃-COMe)[μ-P(Ph)CC(PPh₂)C(O)CH₂C(O)] (4). Compound 4 consists of a triangular ruthenium core that is face-capped by μ₃-COMe methylidyne and μ-P(Ph)CC(PPh₂)C(O)CH₂C(O) phosphido ligands. The kinetics for the conversion of 2 → 4 have been measured in toluene solvent over the temperature range 320-343 K, and based on the observed activation parameters and the inhibitory effect of added CO on the reaction, a rate-limiting step involving a dissociative loss of CO is supported. Heating 4 in the presence of H₂ afforded the phosphinidene-capped cluster H₃Ru₃(CO)₇(μ₃-PPh)[μ-CC(PPh₂)C(O)CH₂C(O)] (5). Crystallographic analysis of 5 has confirmed the loss of the methylidyne moiety and the cleavage of the phosphido PhP-C(dione) bond, and the presence of three edge-bridging hydrides is supported by ¹H NMR spectroscopy. The reaction of 4 with added PPh₃ and PMe₃ has been investigated; the uptake of a single phosphine ligand occurs regiospecifically at one of the phosphido-bound ruthenium centers to give Ru₃(CO)₆L(μ₃-COMe)[μ-P(Ph)CC(PPh₂)C(O)CH₂C(O)] (PPh₃, 6; PMe₃, 7). Compound 6 contains 48e- and exhibits a structural motif similar to that found in 4. Compound 7 readily adds a second PMe₃ ligand to yield the bis-substituted cluster Ru₃(CO)₆(PMe₃)₂(μ₂-COMe)[μ-P(Ph)CC(PPh₂)C(O)CH₂C(O)] (8). The solid-state structure of 8 confirms the loss of two ruthenium-ruthenium bonds and the conversion of the original face-capping μ₃-COMe ligand to a μ₂-COMe moiety that tethers two non-bonding ruthenium centers. The two PMe₃ ligands in 8 coordinate to the same ruthenium center, and the 9e- P(Ph)CC(PPh₂)C(O)CH₂C(O) ligand binds all three ruthenium atoms through the phosphine, phosphido, alkene, and carbonyl moieties. Near-UV irradiation of 8 leads to loss of CO and polyhedral contraction of the triruthenium frame to yield the 48e- cluster Ru₃(CO)₅(PMe₃)₂(μ₃-COMe)[μ-P(Ph)CC(PPh₂)C(O)CH₂C(O)] (9).     

Formation of the silylene-bridged complex Fe2(CO)6(μ2-SiCl2)3 from cis-Fe(CO)4(SiCl3)2: an experimental and computational study

Abstract  

Thermolysis of cis-Fe(CO)₄(SiCl₃)₂ results in the formation of the novel compound Fe₂(CO)₆(μ₂-SiCl₂)₃, which was characterized by single crystal X-ray diffraction. Density functional theory calculations were carried out to elucidate possible reaction steps leading to the formation of Fe₂(CO)₆(SiCl₂)₃, including CO dissociation and chlorine abstraction by a SiCl₃ radical generated from homolytic Fe–Si bond cleavage involving a singlet–triplet intersystem crossing.     

Tethered silyl complexes from nucleophilic substitution reactions at the Si-Cl bond of the chloro(diphenyl)silyl ligand in Ru(SiClPh2)(κ-S2CNMe2)(CO)(PPh3)2

Crystal structure determination of RuH(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (1) confirms that the triphenylphosphine ligands are arranged mutually trans. 1 reacts readily with HSiClPh₂ to eliminate H₂ and produce the six-coordinate silyl complex, Ru(SiClPh₂)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (2). Crystal structure determination of 2 reveals the same geometrical arrangement of ligands as in 1 with the silyl ligand replacing the hydride ligand. The chloride bound to silicon in 2 is replaced through reactions with 2-hydroxypyridine, 2-aminopyridine, and thallium acetate, producing, respectively, the mono-PPh₃ complexes, Ru(κ²(Si,N)-SiPh₂OC₅H₄N)(κ²-S₂CNMe₂)(CO)(PPh₃) (3), Ru(κ²(Si,N)-SiPh₂NHC₅H₄N)(κ²-S₂CNMe₂)(CO)(PPh₃) (4), and Ru(κ²(Si,O)-SiPh₂OCMeO)(κ²-S₂CNMe₂)(CO)(PPh₃) (5). Crystal structure determinations of 3, 4, and 5 confirm that in each case there is formation of a five-membered chelate ring tethering the silyl ligand to ruthenium. In the formation of 3, 4, and 5 the Si-ligand and the two S atoms of the dimethyldithiocarbamate ligand remain meridional but the remaining triphenylphosphine ligand and the carbonyl ligand are interchanged in position leaving the donor atom of the tether trans to the CO ligand. An alternative way of considering the tethered silyl ligands in 3, 4, and 5 is as tethered, base-stabilised, silylene ligands and the structural data give some support for a contribution from this bonding model.     

Synthesis and X-ray crystal structure of the dinuclear copper(I) complex [Cu2((Me-Pk)2En)(PPh3)4](ClO4)2 · 2CHCl3

The new dinuclear copper(I) complex, [Cu₂((Me-Pk)₂En)(PPh₃)₄](ClO₄)₂ · 2CHCl₃ (I), where (Me-Pk)₂En = N,N′-bis(1-pyridin-2-yl-ethylidene)ethane-1,2-diamine), has been synthesized and characterized by elemental analyses, FT-IR, and single-crystal X-ray diffraction method. In this complex, two Cu(PPh₃)₂ units are connected by one (Me-Pk)₂En bridging ligand. The coordination geometry around each copper(I) atom is a distorted tetrahedron formed by two N atoms from (Me-Pk)₂En and two P atoms from the PPh₃ ligands. The distance between two copper atoms is 7.06(1) ?.     

Synthesis and structures of Cs4[(UO2)2(C2O4)(SO4)2(NCS)2] · 4H2O and (NH4)4[(UO2)2(C2O4)(SO4)2(NCS)2] · 6H2O

Single crystals of Cs₄[(UO₂)₂(C₂O₄)(SO₄)₂(NCS)₂] · 4H₂O (I) and (NH₄)₄[(UO₂)₂(C₂O₄)(SO₄)₂(NCS)₂] · 6H₂O (II) have been synthesized and studied by X-ray diffraction. The crystals of both compounds are orthorhombic with the space group Pbam, Z = 2, and unit cell parameters a = 12.0177(3) ?, b = 18.6182(5) ?, c = 6.7573(10) ?, R = 0.0376 (I); a = 11.6539(9) ?, b = 18.3791(13) ?, c = 6.7216(5) ?, R = 0.0179 (II). The main structural units of crystals I and II are [(UO₂)₂(C₂O₄)(SO₄)₂(NCS)₂]⁴⁻ chains belonging to the crystal-chemical group A₂K⁰²B₂²M₂¹ (A = UO₂²⁺, K⁰² = C₂O₄²⁻, B² = SO₄²⁻, M¹ = NCS⁻) of the uranyl complexes. The uranium-containing chains are joined into a three-dimensional framework due to a system of electrostatic interactions with the cesium or ammonium ions in the structure of I. In the structure of II, this framework is additionally stabilized by hydrogen bonds involving the outer-sphere water molecules and ammonium ions. Original Russian Text ? I.V. Medrish, A.V. Virovets, E.V. Peresypkina, L.B. Serezhkina, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 7, pp. 1115–1120.     

Spanning [Pt2(μ-S)2(PPh3)4] metalloligands with 1,4-dimercurated durene

Reaction of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of durene-1,4-bis(mercuric acetate) [AcOHgC₆Me₄HgOAc] in methanol gives the polynuclear complex [{Pt₂(μ-S)₂(PPh₃)₄}₂(μ-1,4-C₆Me₄Hg₂)]²⁺, isolated as its and salts. Positive-ion ESI mass spectra indicate that [{Pt₂(μ-S)₂(PPh₃)₄}₂(μ-1,4-C₆Me₄Hg₂)]²⁺ undergoes fragmentation by successive loss of PPh₃ ligands, while the ESI mass spectrum of the salt showed additional ions [Pt₂(μ-S)₂(PPh₃)₄(HgC₆Me₄HgPh)]⁺ and [Pt₂(μ-S)₂(PPh₃)₄HgPh]⁺ as a result of phenyl transfer from to Hg. A single-crystal X-ray structure determination on [{Pt₂(μ-S)₂(PPh₃)₄}₂(μ-1,4-C₆Me₄Hg₂)](BPh₄)₂ shows that the cation crystallises on a centre of symmetry, with structural features that are comparable to those of the previously characterised complex [Pt₂(μ-S)₂(PPh₃)₄HgPh]BPh₄.     

Dynamic behavior of [(η-C5H4CH3)Cr(CO)2(μ-SBu)Pt(PPh3)2] in solution

The structure and dynamic behavior of complex [(η⁵-C₅H₄CH₃)Cr(CO)₂(μ-SBu)Pt(PPh₃)₂] in solution was studied by multinuclear (¹H, ¹³C, ³¹P) NMR spectroscopy including a phase-sensitive NOESY experiment. Increasing temperature causes rupture of the Cr-Pt bond in the three-membered ring of the complex and rotation of the S-Pt(PPh₃)₂ unit around the Cr-S bond line, followed by formation of a new Cr-Pt bond to close the ring. All activation parameters for this dynamic process have been determined.     

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.     

Reactions of Ru3(CO)12 with 2-pentynal-diethyl-acetal. The crystal structure of Ru2(CO)6[μ-η-{EtC2C(H)(OEt)2}CO{EtC2C(H)(OEt)2}] and its reactivity towards tetraethyl-orthosilicate

The title compound has been obtained in considerable yield by reacting Ru₃(CO)₁₂ with 2-pentynal-diethyl-acetal [CH₃CH₂CCC(H)(OEt)₂] (PDA) in hydrocarbon solvents. The X-ray analysis shows that the title complex belongs to the well known family of the flyover derivatives. Some X-ray structural studies have been reported, many years ago, on di-iron flyover complexes; in contrast only a few examples of diruthenium derivatives have been structurally characterized.The complex contains ethoxy-groups which could potentially undergo hydrolysis in the presence of tetraethyl-orthosilicate (TEOS) in the presence of catalysts. Reactions of complex Ru₂(CO)₆[μ-η⁴-{EtC₂C(H)(OEt)₂}CO{EtC₂C(H)(OEt)₂}] with TEOS in the presence of HCl or of NaF (as catalysts) have been attempted. An inorganic-organometallic sol-gel material containing the skeleton of the complex has been obtained and characterized with IR-Raman, XRD on powders and SEM microscopy.     

Reactions of Cu3(dppm)3(μ3-OH)(ClO4)2 (dppm = bis-(diphenylphosphino) methane) with Soft Heterocumulenes

The reaction of [Cu₃(dppm)₃(μ₃-OH)](ClO₄)₂ (1) with heterocumulenes (XCS; X = NPh, NMe and S) has been studied. The μ₃-OH ligand inserts into PhNCS and MeNCS only in the presence of methanol. Insertion products are formed in accord with earlier observations made with copper(I)-aryloxides. On heating, the insertion products convert to a S bridged cluster [Cu₄(dppm)₄(μ₄-S)](ClO₄)₂ (8), having a tetrameric core. However, in the reaction with CS₂, 1 is converted to 8 even at room temperature in the presence of methanol. On the other hand, the dimeric complex [Cu₂(dppm)₂(CH₃CN)₄](ClO₄)₂, reacts with CS₂ to give (diphenylphosphinomethyl)-diphenylphosphine sulfide, Ph₂P-CH₂-P(S)Ph₂ (dppmS), which forms the complex [Cu(dppmS)₂]ClO₄ (9). A single crystal X-ray crystallographic study of 9, the first copper(I) complex of dppmS has been taken up to confirm the mono-oxidation of the dppm ligand and the nuclearity of the complex. Reactions of complex 1 with heterocumulenes and with elemental sulfur, are compared.     

Ligand substitution in the mixed-metal cluster PhCCo2Ni(CO)6Cp by 2,3-bis(diphenylphosphino)maleic anhydride (bma): An intimate picture involving the stepwise conversion of the trinuclear cluster PhCCo2Ni(CO)4(η-bma)Cp to the mononuclear compound CpNi[PPh2CPhCC(PPh2)C(O)OC(O)]

Heating the mixed-metal cluster PhCCo₂Ni(CO)₆Cp with the diphosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) in 1,2-dichloroethane proceeds by CO loss and formation of the cobalt-bridged cluster PhCCo₂Ni(CO)₄(η²-bma)Cp (2). The bma ligand is fluxional in solution and is in equilibrium with the cobalt-chelated isomer, as demonstrated by VT IR and ³¹P NMR measurements. The van’t Hoff parameters (ΔH = 1.49 ± 0.02 kcal/mol; ΔS = 12.0 ± 0.1 eu) for the chelate-to-bridge equilibrium have been evaluated from IR band-shape analyses of the in-phase anhydride carbonyl stretching band over the temperature range 173-116 K. Cluster 2 readily loses CO to furnish the cluster PhCCo₂Ni(CO)₃(μ,η²-bma)Cp (3), where the 6e− donor bma ligand chelates one of the cobalt centers via the phosphine groups and is tethered to the second cobalt center by the maleic anhydride π bond. Continued heating of cluster 3 is followed by the formation of 50e− cluster Co₂Ni(CO)₄Cp[μ₂,η²,η¹-C(Ph)CC(PPh₂)C(O)OC(O)](μ₂-PPh₂) (4), which in turn gives the mononuclear complex CpNi[PPh₂CPhCC(PPh₂)C(O)OC(O)] (5) as the end-product of the thermolysis reaction. Each of these new compounds has been isolated and their thermolysis reactivity independently examined, allowing for the unequivocal sequence associated with the decomposition of PhCCo₂Ni(CO)₄(η²-bma)Cp to be established. Compounds 2-5 have been fully characterized in solution by IR and NMR(¹H, ¹³C, ³¹P) spectroscopies, and the solid-state structures of all four products have been determined by X-ray crystallography. The solution spectroscopic data of the new products are compared with the X-ray diffraction structures and the structural highlights of each compound are discussed. The coordination of the maleic anhydride π bond in PhCCo₂Ni(CO)₃(μ,η²-bma)Cp (3) provides crucial insight into one of the necessary requirements for P-C bond cleavage of the bma ligand at a tetrahedral cluster. The reactivity of the heterometallic cluster PhCCo₂Ni(CO)₄(η²-bma)Cp is contrasted with its homometallic analogue PhCCo₃(CO)₇(η²-bma).