Garry F. Warnock

Highly reduced organometallics XXVII. Synthesis, isolation and characterization of trisodium tricarbonylcobaltate(3 -), and initial studies on its derivative chemistry

Abstract Reduction of A[Co(CO) 4 ] by three equivalents of A (A = sodium or potassium) in liquid ammonia provides salts containing tricarbonylcobaltate(3 -). A satisfactorily pure sodium compound, Na 3 [Co(CO) 3 ] is described for the first time. Reactions of A 3 [Co(CO) 3 ] with two equivalents of Ph 3 ECl (E = Ge, Sn, Pb) provides 50–70% yields of trans -(Ph 3 E) 2 Co(CO) 3 − which have been isolated as analytically pure Et 4 N + salts. Treatment of liquid ammonia slurries of K 3 [Co(CO) 3 ] with three equivalents of NH 4 Cl in the presence of PR 3 or CNR, results in evolution of hydrogen gas and the formation of Co(CO) 3 L − . In the case of L = t-BuNC, the first such isocyanide substituted carbonylcobaltate(1 -) species was prepared and isolated in a 67% yield by this procedure. A possible pathway for the formation of Co(CO) 3 L − from K 3 [Co(CO) 3 ] is discussed in light of similar protonation reactions reported for other carbonylmetallate trianions.

Synthesis and ligand substitution reactions of [Ta(CO)5NH3]−1☆

Abstract Protonation of Na 3 [Ta(CO) 5 ] in liquid ammonia provides the thermally unstable Na[Ta(CO) 5 NH 3 ], which may be isolated as the crystalline and deep violet salt [Ph 4 As][Ta(CO) 5 NH 3 ]. Sodium amminepentacarbonyltantalate(1−) reacts with PMe 3 , PPh 3 , P(OMe) 3 , AsPh 3 , SbPh 3 , CNtBu and CN − at about 0°C in NH 3 /THF to give exclusively the corresponding [Ta(CO) 5 L] z . These have been isolated as tetraethylammonium salts in 54–84% yields.

Characterization of pentacarbonylvanadate(–III) and hydridopentacarbonylvnadate(–II) by 13C, 15V, and 1H n.m.r. spectroscopy

N.m.r. spectra of highly reduced vanadium carbonyls containing 99% enriched 13CO in liquid ammonia at –50 °C provide the first direct spectroscopic evidence for the existence of Na3[V(CO)5] and Na2[HV(CO)5] in solution.