Syntheses and Structures of Tungsten <i>o</i>-(Diphenylphosphino)benzaldehyde Complexes Bearing π-Bonded Aldehyde Groups

Reaction of the bidentate ligand Ph2P(o-C6H4)C(O)H (abbreviated as PCHO) with W(CO)3(η3-(MeNCH2)3) at room temperature affords W(CO)3(η1-PCHO)(η3-PCHO) (1), which subsequently loses a carbonyl ligand to give W(CO)2(η3-PCHO)2 (2). Further treatment of 2 with PCHO in refluxing benzene results in carbon−carbon coupling of the PCHO ligands to produce W(CO)(η3-PCHO)(η3-(PCHO)2) (3). The structures of 1−3 have been determined by an X-ray diffraction study. The PCHO ligands in these compounds act as chelating phosphine−aldehydes with the aldehyde groups coordinating in a π fashion.