508181-90-6Relevant academic research and scientific papers
Steric control of cyclometallation reactions in Schiff-base complexes of cobalt(I) containing an anchoring diphenylphosphanyl group
Klein, Hans-Friedrich,Beck, Robert,Floerke, Ulrich,Haupt, Hans-Juergen
, p. 3305 - 3312 (2007/10/03)
2-(Diphenylphosphanyl)alkyliminobenzaldehydes (2-Ph2PC6H4CHNR) react with [CoCH3(PMe3)4] forming five-membered metallacycles in complexes [(2-Ph2PC6H4CNR-C,P)Co (PMe3)3] [1: R = C2H5, 2: R = CH(CH3)2, 3: R = cyclo-C6H11] while the ortho-metallation pathway is selectively followed in the formation of [{2-Ph2PC6H3(CHNR)-C1,P}Co (PMe3)3] [4: R = C(CH3)3]. The presence of a four-membered cobaltocycle in the molecular structure of 4 was confirmed by X-ray analysis. Carbonylation of 2 and 3 gives the monocarbonyl derivatives [(2-Ph2PC6H4CNR-C,P)Co(C-O) (PMe3)2] [5: R = CH(CH3)2, 6: R = cyclo-C6H11] while 4 undergoes ring expansion by insertion forming [{2-Ph2PC6H3(CHNR)CO-C,P}Co(CO) (PMe3)2] [7: R = C(CH3)3], Monosubstitution occurs under 1 bar of ethene giving the π-ethene complexes [(2-Ph2PC6H4CNR-C, P)Co(C2H4)(PMe3)2] [8: R = CH(CH3)2, 9: R = cyclo-C6H11] and [{2-Ph2PC6H3(CHNR)-C1,P}Co (C2H4)(PMe3)2] [10: R = C(CH3)3]. The molecular structure of 9 shows an equatorial π-ethene ligand Iodomethane oxidizes 2 and 3 to afford the cobalt(II) complexes [(2-Ph2PC6H4CNR-C, P)CoI(PMe3)2] [11: R = CH(CH3)2, 12: R = cyclo-C6H11] and oxidatively adds to 4 to give mer-trans-[{2-Ph2PC6H3(CHNR)-C1, P}CoI(CH3)(PMe3)2] [13: R = C(CH3)3]. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
