Geoffrey Wilkinson

Triphenylphosphonium and trimethyl-phosphonium hexachloroosmates (IV) and their reactions with alkylating agents; Methyl and trimethylsilylmethyl osmium compounds; trans-di-chlorotetrakis(trimethylphosphine)-osmium(II); Tetrakis(trimethyl-silylmethyl)oxoosmium(VI)

Abstract The reported synthesis of tetrachlorobis(triphenylphosphine) osmium(IV) is shown to proceed via initial formation of a salt, [Ph 3 PH] 2 [OsCl 6 ], front which the corresponding [Me 3 PH] + salt can be obtained by exchange; the latter salt reacts with acetone to give [Me 3 PC(OH)Me 2 ] 2 [OsCl 6 ]. The action of methyl and trimethylsilylmethyl alkylating agents on the hexachloroosmates and on OsCl 3 (PPh 3 ) 3 to give σ-alkyls is reported. The complex trans -OsMe 2 (PPh 3 ) 4 reacts with carbon monoxide to give the corresponding bis acetyl. The complex trans -OsCl 2 (PMe 3 ) 4 is resistant to attack by alkylating agents. The interaction of bis(trimethylsilylmethyl)magnesium with OsO 4 in pentane at −70°C yields (Me 3 SiCH 2 ) 4 OsO.