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

Enantiopure 2-(chlorocarbonyl)phosphametallocenes [MCp*(2-{COCl}-3,4-Me2-5-Ph-PC4)] (M = Fe, Ru) react with phospholide anions to give 2-phosphametallocene-2′-acylphospholides K[MCp*(2-CO-2′-{3′,4′-Me2-5′-PhPC4}-3,4-Me2-5-Ph-PC4)] (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 C2- (or pseudo-C2- when M = Ru) symmetric form of [{MCp*(3,4-Me2-5-Ph-PC4)}2-2,2′-(CO)] (M = Fe, Ru; Fe, Fe) with high (>95%) diastereoselectivity. X-Ray structures of these ligands coordinated to [RuCp*Cl] and [PtCl2] 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.