Self-assembled rings and coordination polymers starting from [RhCl2(CO)2] and diphosphane ligands

In the past few years we have reported on the synthesis of some 1D coordination polymers based on Rh(I) and Ir(I) halocarbonyls and some diphosphano ligands, confirming the high versatility of these ligands in coordination self-assembly. Significant results obtained with diphosphanes of general formula PPh2(CH2)nPPh2 (n=5-12) are here summarized. Generally, the formation of coordination rings is observed and sometimes these are the only species isolated; interestingly, rings with n=6 and 8, subsequently evolve to the corresponding polymers, probably through a reaction of ring-opening polymerization.