Selective cleavage of P-N bonds and the conversion of rhodium N-pyrrolyl phosphine complexes into diphosphoxane-bridged dimers

Rhodium(I) complexes trans-[RhCl(CO)(PR2{NC4H3C(O)ME-(2)})2] (R = Ph, NC4H4) react with water to give the diphosphoxane-bridged dimers [Rh2Cl2(CO)(2)(mu-PR2OPR2)(2)] following cleavage of the P-N bonds to the 2-acetyl-N-pyrrolyl groups. The two dimers have been crystallographically characterized and show a number of structural differences, with the PPh2OPPh2 compound possessing semibridging chloride and carbonyl ligands whereas the P(NC4H4)(2)-OP(NC4H4)(2) compound contains only terminal chlorides and carbonyls. No evidence for cleavage of the P-N bonds involving the unfunctionalized N-pyrrolyl groups in trans-[RhCl(CO)(P{NC4H4}(2)-{NC4H3C(O)Me-(2)})(2)] was observed.