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

Abstract

Reactions of [Cp*MCl 2] 2 ( 1a: M=Rh, 1b: M=Ir; Cp*=C 5Me 5) with 2-methoxyphenylphosphines at room temperature gave the corresponding 1η-P coordination complexes, [Cp*MCl 2(PPh 3− n R n )] ( 2: n=1; 4: n=2; 6b: n=3 for R=C 6H 4-2-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= PPh 2(C 6H 4-2- 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(C 6H 4-2-MeO)(C 6H 4-2- 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(C 6H 4-2-MeO) 2(C 6H 4-2- O)), whereas the reaction with 1b at reflux in EtOH generated Cp*Ir(TMMPP- P, O, O′) ( 8b) (TMMPP- P, O, O′= P(C 6H 4-2-MeO)(C 6H 4-2- 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 KPF 6, giving [Cp*Rh{ PPh 2(C 6H 4- O-CRCHCH CR}](PF 6) ( 9a: R= p-MeC 6H 4; 9b: R=Ph) with a ( P, O, C) tridentate ligand, in which X-ray crystal analysis of 9a was performed.