CO substitution in the mixed-metal clusters PhCCo2Ni(CO)6Cp and PhCCo2Mo(CO)8Cp by (Z)-Ph2PCH=CHPPh2. X-ray diffraction structures and proof of ligand bridging in PhCCo2Ni(CO)4[(Z)-Ph2PCH=CHPPh2]Cp and PhCCo2Mo(CO)6[(Z)-Ph2PCH=CHPPh2]Cp

Synthesis of the chiral tetrahedral clusters RCCo2NiCp(CO)4(bmf) (R=H, Ph) and thermally promoted diphosphine ligand activation: Regiospecific P–C bond scission and X-ray diffraction structure of Co2NiCp(CO)4[μ2,η2,η1-C(H)CC(PPh2)C(O)OCH(OMe)](μ-PPh2)

“…The IR spectral data for the terminal Co-CO bands in RCCo 2 NiCp(CO) 4 (bmf) are in excellent agreement with those data reported for PhCCo 2 -NiCp(CO) 4 [(Z)-Ph 2 PCH@CHPPh 2 ], whose diphosphine ligand bridges the two cobalt centers [3]. The carbonyl stretching band belonging to the ester moiety of the bmf ring in both products is found at 1767 cm À1 and is insensitive to the nature of the l 3 -hydrocarbyl capping ligand in each cluster [12].…”

“…hypho polyhedral cluster opening in going from HCCo 2 NiCp(CO) 4 (bmf) to Co 2 NiCp(CO) 4 [l 2 ,g 2 ,g 1 -C(H)C@C(PPh 2 )C(O)OCH(OMe)](l-PPh 2 ) [17]. The Co(1)-Co (2) and Ni-Co(1) bond distances of 2.612(5) and 2.463(5) Å , respectively, are unremarkable relative to other structurally characterized Co and Ni containing clusters of this genre [1][2][3]18]. and the internuclear distance of 3.85(2) Å between the NiÁ Á ÁCo (2) centers rules out any direct bonding between these atoms, consistent with Polyhedral Skeletal Electron Pair (PSEP) theory that guides the polyhedral opening in Co 2 NiCp-(CO) 4 )[l 2 ,g 2 ,g 1 -C(H)C@C(PPh 2 )C(O)OCH(OMe)](l-PPh 2 ) [17].…”

“…The ligand substitution behavior of the mixed-metal clusters RCCo 2 NiCp(CO) 6 (R = Ph, H) with the rigid diphosphine ligands (Z)-Ph 2 PCH@CHPPh 2 and 2,3-bis(diphenylphosphino)maleic anhydride (bma) has been recently studied by our groups [1][2][3]. While the former archetypal diphosphine reacts with PhCCo 2 NiCp(CO) 6 to furnish the stable cobalt-cobalt bridged cluster PhCCo 2 NiCp(CO) 4 -[(Z)-Ph 2 PCH@CHPPh 2 ], the latter diphosphine, with its electron-withdrawing maleic anhydride moiety, displays more diverse reaction chemistry.…”

Regiospecific and sequential P–C bond activation/cluster transformations in the reaction of PhCCo2MoCp(CO)8 with the diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf)

“…Both bmf-substituted clusters exist as a ca. 70:30 mixture of diastereomers in solution and are obtained in good yield from thermolysis of the RCCo 2 NiCp(CO) 6 in the presence of added bmf ligand. Here the bridging bmf ligand is equatorially disposed across the Co-Co bond in each product, as deduced by NMR analyses.…”

“…The course and outcome of these reactions depend on several variables, one of which is the metallic composition of the cluster, as shown in Scheme 1 for the phenyl-capped clusters PhCCo 3 (CO) 7 (bma) and PhCCo 2 NiCp(CO) 4 (bma). Thermolysis of the bma-substituted Co 3 and Co 2 Ni clusters furnishes the structurally different phosphido-bridged clusters Co 3 (CO) 6 [l 2 ,g 2 ,g 1 [6] clusters have been shown to be stable under conditions comparable to those used to promote the transformations illustrated in Scheme 1. The synthesis and reactivity of the chiral clusters HCCo 2 NiCp(CO) 4 (bmf) and PhCCo 2 NiCp(CO) 4 (bmf) have recently been described by us [4].…”