Labile complexes of the (RuTp(pn))+ (Tp = tripyrazolylborate, pn = Ph2PCH2CH2NMe2) fragment including the dinitrogen ligand

X-ray crystallography and nuclear magnetic resonance spectroscopy were done to characterize the (RuTp(pn))+ fragment. It was found that the fragment has a strong sigma acceptor and a weak pi donor through which reversible complexes with a variety of sigma donor ligands such as dinitrogen, water, acetone, CO and vinylidene, can be formed. Theoretical calculations and crystallographic data revealed that the order of increasing stabilities of the (TpRu(pn)L)+ complexes with respect to the ligands are CF3SO3- < acetone or water < CH3CN < N2 < CO < vinylidene.