The coordination chemistry of phosphonites

• Seven Mo(0) tetracarbonyl complexes of new phosphonite ligands have been synthesized and characterized by NMR spectroscopy.
• X-ray crystal structures of four of the complexes have been determined.
• The electron-donor abilities and steric effects of the phosphonite ligands can be independently adjusted.

Transition metal complexes of phosphonites are of interest as catalysts because transition metal complexes of the closely related phosphines (PR3), phosphinites (PR2XR), and phosphites (P(XR)3) have excellent catalytic properties for a variety of organic transformations. However, there has been surprisingly little research on the coordination chemistry of phosphonites. To help in remedying this deficiency, we have begun a study of the coordination chemistry of phosphonite ligands. In this project, seven new phosphonite ligands of the type RP(OR′O) (R = phenyl, 2-thienyl; ORO = 1,1′-bi-2-naphthoxy, 4-tert-butylphenoxy, and catechoxy) and their cis-Mo(CO)4 complexes have been synthesized. The complexes have been characterized by 31P, 13C, and 1H NMR spectroscopy, and X-ray crystal structures of four of the complexes have also been determined.

Seven cis-tetracarbonylmolybdenum complexes of RP(OR′O) phosphonite ligands (R = phenyl, 2-thienyl; ORO = 1,1′-bi-2-naphthoxy, 4-tert-butylphenoxy, and catechoxy) have been synthesized and characterized by multinuclear NMR spectroscopy and X-ray crystallography. These studies indicate that the electron-donor abilities depend on the R group while the steric effects depend on the R′ group.Figure optionsDownload as PowerPoint slide