Three-Fold Intramolecular Ring-Closing Metatheses Involving Square-Planar Platinum Complexes with cis-Phosphorus Donor Ligands: Syntheses, Structures, and Properties of Parachute-like Complexes

Reactions of the phosphite and phosphine complexes cis-PtCl 2((PX(CH2)mCH=CH2)3)2 (X/m = O/3, O/4, O/5, -/5, -/6) with Grubbs' catalyst, followed by hydrogenations, yield cis-PtCl2(P(X(CH2)(2m+2)X)3P) (6-40%). Crystal structures establish parachute-like motifs in which one X(CH2)(2 m+2)X bridge lies roughly in the platinum coordination plane, and the others lie above and below.