Reactions of bis[dichloro(pentamethylcyclopentadienyl)rhodium(III) and -iridium(III)] with aromatic phosphine bearing a methoxy group at an ortho-position: double insertion of 1-alkynes into a RhO bond

Reactions of [Cp*MCl2]2 (1a: M=Rh, 1b: M=Ir; Cp*=C5Me5) with 2-methoxyphenylphosphines at room temperature gave the corresponding 1η-P coordination complexes, [Cp*MCl2(PPh3−nRn)] (2: n=1; 4: n=2; 6b: n=3 for R=C6H4-2-MeO). Reaction of 1 with (2-methoxyphenyl)diphenylphosphine at reflux in diglyme underwent demethylation to afford Cp*MCl(MMMPP-P,O) (3) (M=Rh, Ir; MMMPP-P,O=PPh2(C6H4-2-O)) with a (P,O) chelating ligand. In the reaction with bis(2-methoxyphenyl)phenylphosphine, Cp*MCl(BMMPP-P,O) (5) (M=Rh, Ir; BMMPP-P,O=PPh(C6H4-2-MeO)(C6H4-2-O)) was generated at reflux in a mixture of diglyme and MeOH. Tris(2-methoxyphenyl)phosphine reacted with 1a at reflux in MeOH to give Cp*RhCl(TMMPP-P,O) (7a) (TMMPP-P,O=P(C6H4-2-MeO)2(C6H4-2-O)), whereas the reaction with 1b at reflux in EtOH generated Cp*Ir(TMMPP-P,O,O′) (8b) (TMMPP-P,O,O′=P(C6H4-2-MeO)(C6H4-2-O)2) with a (P,O,O′) tridentate ligand. Crystal structural analyses of 3a, 5a and 8b were carried out. Complex 3a underwent a double insertion of alkyne into a RhO bond on treatment with phenylacetylene or p-tolylacetylene in the presence of KPF6, giving [Cp*Rh{PPh2(C6H4-O-CRCHCHCR}](PF6) (9a: R=p-MeC6H4; 9b: R=Ph) with a (P,O,C) tridentate ligand, in which X-ray crystal analysis of 9a was performed.