Synthesis and study of the stability of phosphane palladacycles

The chemistry of cyclometalated compounds has attracted much research interest in past years. They are known for their ample applications in numerous fields: organic synthesis, photochemistry, catalysis, and as potential biologically active materials. Numerous Palladacycles bearing Ph₂PCH₂PPh₂-P,P, (dppm) were described before showing different ways of coordination.

We now report Palladacycles of the type [Pd₂(Ph₂PCH₂PPh₂−P,P)₂(C,N:C,N)] can undergo a spontaneous slow chelate−to−bridging diphosphine coordination shift in solution when (C,N:C,N) is derived from −4,4´−sulfonyldianiline or −4,4´−oxydianiline and 2,3,4-trimethoxybenzylidene. Following this strategy a synthetic procedure was devised that culminates in isolation of the first crystallographically characterized tetranuclear palladium structures.