N,N′,N″-Triphenylguanidinate(−1) complexes of ruthenium, osmium and iridium: synthesis and X-ray crystal structures

N,N′,N″-Triphenylguanidine (TpgH) reacts with [Ru(H)2(CO)(PPh3)3] in refluxing toluene and with [Os(H)2(CO)(PPh3)3] in refluxing o-xylene to yield the guanidinate(−1) complexes [RuH(Tpg)(CO)(PPh3)2] (1) and [Os(Tpg)2(CO)(PPh3)] (2), respectively. The reaction of TpgH with [RuCl2(PPh3)3] in refluxing toluene affords a new route to the known complex [Ru(Tpg)2(CO)(PPh3)] (3). Finally the reaction of mer-[Ir(H)3(PPh3)3] with TpgH in refluxing toluene yields the iridium(III) dihydride complex [Ir(H)2(Tpg)(PPh3)2] (4). X-ray crystal structure determinations are reported for (1) and (4).