335202-95-4Relevant academic research and scientific papers
Isomerisation and fragmentation of sulfur-containing organometallacycles on dicobalt centres induced by phosphorus donor ligands
King, Jason D.,Mays, Martin J.,Pateman, Giles E.,Raithby, Paul R.,Solan, Gregory A.,Conole, Grainne,McPartlin, Mary
, p. 202 - 210 (2001)
Treatment of the dibridged dicobalt complex [Co2(μ-PPh2){μ-η1(S): η1(C):η2(C)-SPhC(O)CR′CR}(CO)4 ] (R′ = R = H 1a) with L, at ambient temperature, affords an inseparable mixture of two mono-substituted isomeric complexes of general formula [Co2(μ-PPh2){μ-η1(S):η 1(C):η2(C)-SPhC(O)CHCH}(CO)3(L)] [L = P(OMe)3 2a/3a, PPhMe2 2b/3b], differing only in the metal centre at which L is coordinated. When the reaction is performed with [Co2(μ-PPh2){μ-η1(S):η 1(C):η2(C)-SPhC(O)CR′CR}(CO)4] [R′ = Me, R = H 1b], in which R′ and R are inequivalent, a similar mixture of inseparable isomers is isolated, [Co2(μ-PPh2){μ-η1(S):η 1(C):η2(C)-SPhC(O)-CMeCH}(CO)3(L)] [L = P(OMe)3 4a/5a, PPhMe2 4b/5b] and, in addition, a third separable isomer, [Co2(μ-PPh2)-{μ-η1(S):η 1(C):η2(C)-SPhC(O)CHCMe}(CO)3(L)] [L = P(OMe)3, 6a, PPhMe2 6b], in which R′ and R have interchanged. Addition of a further equivalent of L at elevated temperature to mixtures of 2/3 results in both carbonyl substitution and a rearrangement of the bridging ligand assembly to give [Co2(μ-SPh){μ-η1(P):η1(C) : η2(C)-PPh2CRCR′C(O)}(CO)2(L) 2] [R′ = R = H; L = P(OMe)3 7a, PPhMe2 7b] in high yield. A similar transformation is achieved on interaction of 4/5 and 6 with L leading to [Co2(μ-SPh){μ-η1(P):η1(C) :η2(C)-PPh2CRCR′C(O)}-(CO)2 (L)2] [R′ = Me, R = H; L = P(OMe)3 8a, PPhMe2 8b] and, in addition, [Co2(μ-SPh){μ-η1(P):η1(C) :η2(C)-PPh2-CR′CRC(O)}(CO)2(L )2] [R′ = Me, R = H; L = P(OMe)3 9a, PPhMe2, 9b], in which the positions of R′ and R are reversed. Reaction of 2a/3a with triphenylphosphine, gives the mixed phosphite-phosphine rearranged species [Co2(μ-SPh){μ-η1(P):η1(C) :η2(C)-PPh2CHCHC(O)}(CO)2{P(OMe) 3}(PPh3)] 10 as the sole product. The facility of the bridging ligands in 1 to undergo a range of bond-breaking (C-S and C-C) and bond-forming (C-S, C-P and C-C) reactions induced by phosphorus donor ligand addition is discussed and pathways postulated. The single crystal X-ray structures of 2b, 7a and 10 are described. The Royal Society of Chemistry 2001.
