SYNTHESIS AND LIGAND SUBSTITUTION-REACTIONS OF [TA(CO)(5)NH3](-1)

Protonation of Na-3[Ta(CO)(5)] in liquid ammonia provides the thermall y unstable Na[Ta(CO)(5)NH3], which may be isolated as the crystalline and deep violet salt [Ph(4)As][Ta(CO)(5)NH3]. Sodium amminepentacarbon yltantalate(1 -) reacts with PMe(3), PPh(3), P(OMe)(3), AsPh(3), SbPh( 3), CNtBu and CN- at about 0 degrees C in NH3/THF to give exclusively the corresponding [Ta(CO)(5)L](z). These have been isolated as tetraet hylammonium salts in 54-84% yields.