Semi-Rigid Bis-Phosphane Ligands for Metallamacrocycle Formation

Abstract

Efficient syntheses are described for the new bridging bis-phosphanes DPPN (4) and DPEN (5) built around the restricted rigidity of a 2,7-dialkoxynaphthalene backbone. These show marked preference for bridging pairs of metal atoms (PtII, Mo0) to form metallamacrocycles or oligomers. Single-crystal X-ray structure determinations of four dimeric complexes with PtII and Mo0 are reported. The dimeric platinum complexes can be obtained as the kinetically favoured trans,trans products, which isomerise to the cis,cis forms in the presence of free ligand. cis,cis-[Pt2Cl4(DPEN)2] (12) shows marked hydroformylation catalytic activity.