Ligand substitution in HC(O)CCo3(CO)9 with 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd): Diphosphine ligand fluxionality, decarbonylation of the formyl moiety and competitive P–Ph bond cleavage reactivity

Ligand substitution in the tetrahedrane clusters RCCo2Mo(η5-indenyl)(CO)8 with 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd): Influence of the carbyne and indenyl ligands on the stability of the substitution products and X-ray diffraction structures of HCCo2Mo(η5-indenyl)(CO)6(μ-bpcd) and CoMo(η5-indenyl)(μ-CPh)(CO)2(μ-bpcd)Cl

“…These latter two bands are readily assignable to the vibrationally coupled C@O groups of the dione ring [20]. The 31 P NMR spectrum of 2 displays a single 31 P resonance at d 29.70 that is consistent with the presence of a bridging bpcd and in agreement with those chemical shifts reported by us in other bpcd-bridged clusters [3,4,21]. Unfortunately the 31 P NMR data do allow us to unequivocally assign the metal-metal bond that is bridged by the bpcd ligand in cluster 2.…”

“…Accordingly, we have begun to devote a greater amount of our attention to the examination of the chemistry associated with the bpcd ligand. These particular ligands, whose structures are depicted below, react with RCCo 3 (CO) 9 to give the corresponding diphosphinesubstituted clusters RCCo 3 (CO) 7 (P-P) [1][2][3][4][5]. The RCCo 3 (CO) 7 (P-P) clusters are of interest as they display dynamic, non-dissociative chelate-to-bridge diphosphine isomerization about the cluster polyhedron and facile cluster/diphosphine activation at ambient temperatures.…”

“…With respect to the latter reactivity, we have found two decomposition manifolds for the RCCo 3 (CO) 7 (P-P) clusters that are influenced by the nature of the capping carbyne group. Scheme 1 illustrates the two cluster/ diphosphine activation reactions for the bpcd-substituted clusters PhCCo 3 (CO) 7 (bpcd) and HCCo 3 (CO) 7 (bpcd), where the benzylidene-containing cluster Co 3 (CO) 6 -[l 2 ,g 2 ,g 1 -C(Ph)C@C(PPh 2 )C(O)CH 2 C(O)](l 2 -PPh 2 ) and the phosphido-bridged cluster Co 3 (CO) 7 [l 2 ,g 2 ,g 1 -P(Ph)C@C(PPh 2 )C(O)CH 2 C(O)] are formed, respectively [3,4]. The former cluster arises from an oxidative cleavage of one of the Ph 2 P-C(dione) bonds, followed by the reductive coupling of the l 3 -benzylidyne group with the transient Co-C(dione) moiety, with the latter tricobalt cluster deriving from the loss of one of the phenyl groups from the bpcd ligand and the original methylidyne capping group.…”

Experimental and Computational Studies of the Isomerization Reactions of Bidentate Phosphine Ligands in Triosmium Clusters: Kinetics of the Rearrangements from Bridged to Chelated Isomers and X-ray Structures of the Clusters Os3(CO)10(dppbz), 1,1-Os3(CO)10(dppbzF4), HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6H4PPh2], and HOs3(CO)9[μ-1,2-PhP(C6HZhang1, Kandala2, Yang3 et al. 2011OrganometallicsSelf Cite21260View full textAdd to dashboardCite

“…Our interest in the coordinative flexibility of diphosphine ligands in polynuclear clusters , led us to measure the kinetics for the conversion 2 → 3 . The isomerization reactions were conveniently monitored by UV−vis spectroscopy, under CO, over the temperature range 318−343 K; the first-order rate constants given in Table were obtained.…”

“…One of us (M.G.R.) has held a long-term interest in the synthesis and mechanistic study of Ru 3 , Os 3 , and tetrahedrane clusters, containing rigid diphosphine ligands. ,− Several of these reports have addressed the dynamic isomerization of the ancillary diphosphine ligand about the cluster core, as illustrated for the cluster compound Os 3 (CO) 10 (dppen) (where dppen = (Z)-1,2-bis(diphenylphosphino)ethylene) in eq . This particular reaction is reversible, and the thermodynamically favored isomer contains a chelating dppen ligand with a K eq value of 6.9 over the temperature range 358−373 K .…”