Base induced P–C bond cleavage in a coordinated bis(dimethylphosphino)methane ligand

Abstract

Treatment of fac-[Mn(CNR)(CO)₃{(PMe₂)₂CH₂}]ClO₄ (1a R = Ph, 1b R = ^tBu) with KOH produced the cleavage of one of the P–C bonds of the coordinated dmpm ligand, resulting in the formation of phosphine–phosphinite complexes fac-[Mn(PMe₂O)(CNR)(CO)₃(PMe₃)] (2a,b). Alkoxides such as NaOMe and NaOEt promoted similar processes in 1a,b, yielding fac-[Mn(CNR)(CO)₃(PMe₃)(PMe₂OR′)]ClO₄ (3a R = ^tBu, R′ = Me; 3b R = Ph, R′ = Me; 4a R = ^tBu, R′ = Et; 4b R = Ph, R′ = Et) derivatives. The phosphinite ligand in 2a,b can be sequentially protonated by addition of 0.5 and 1 equivalent of HBF₄ leading to fac-[{Mn(CNR)(CO)₃(PMe₃)(PMe₂O)}₂H]BF₄ (6a,b) and fac-[Mn(CNR)(CO)₃(PMe₃)(PMe₂OH)]BF₄ (5a,b), respectively.