Synthesis, isolation, and characterization of trisodium tricarbonyliridate(3-), Na-3[Ir(CO)(3)]. Initial studies on its derivative chemistry and structural characterizations of trans-[Ir(CO)(3)(EPh3)(2)](-), E = Ge, Sn, andtrans-[Co(CO)(3)(SnPh3)(2)](-)

Reduction of Na[Ir(CO)(4)] by sodium metal in (Me2N)(3)PO, followed by trea tment with liquid ammonia, provided high yields (ca. 90%) of unsolvated Na- 3[Ir(CO)(3)], a thermally stable, pyrophoric orange solid. This substance c ontains iridium in its lowest known formal oxidation state of -3 and has be en characterized by IR spectroscopy, elemental analyses, and derivative che mistry, i.e., by its conversion to the triphenylgermyl and triphenylstannyl complexes, trans-[Ir(CO)(3)(EPh3)(2)](-), E = Ge, Sn. Single-crystal X-ray structures of the tetraethylammonium salts of these species, as well as [C o(CO)(3)(SnPh3)(2)](-), confirm the trigonal bipyramidal nature of the anio ns, originally predicted on the basis of their IR spectra in the carbonyl s tretching frequency region. These structural characterizations provide impo rtant additional evidence for the presence of metal tricarbonyl units in Na -3[M(CO)(3)], M = Co, Ir..