Diastereoselective synthesis and coordination chemistry of enantiopure keto-bis-(2-phosphametallocene)s

Enantiopure 2-(chlorocarbonyl)phosphametallocenes [MCp*(2-{COCl}-3,4- Me ₂-5-Ph-PC ₄)] (M = Fe, Ru) react with phospholide anions to give 2-phosphametallocene-2′-acylphospholides K[MCp*(2-CO- 2′-{3′,4′-Me ₂-5′-PhPC ₄}-3,4- Me ₂-5-Ph-PC ₄)] (M = Fe, Ru) and these have been converted into keto-bis-(2-phosphametallocene)s through reaction with [FeClCp* (tmeda)]; templation of this process with CuBr gives rise to the C ₂- (or pseudo-C ₂- when M = Ru) symmetric form of [{MCp*(3,4- Me ₂-5-Ph-PC ₄)} ₂-2,2′-(CO)] (M = Fe, Ru; Fe, Fe) with high (>95%) diastereoselectivity. X-Ray structures of these ligands coordinated to [RuCp*Cl] and [PtCl ₂] centres show that the spatial orientation of the very flexible keto-bis-(2-phosphametallocene) structure is highly responsive to the coordination sphere of the chelated platinum or ruthenium centre.