SYNTHESIS AND REACTIONS OF THE METAL BASE [(C5ME4H)CO(PME3)2]

The (tetramethylcyclopentadienyl)cobalt complex [(C5Me4H)Co(PMe3)2] (1), which is prepared from [CoCl(PMe3)3] and LiC5Me4H in 75% yield, behaves like a Lewis base and reacts with NH4PF6, CH3I, or CF3SO3CH3 by oxidative addition to give the cations [(C5Me4H)CoX(PMe3)2]+ (X = H, I, CH3; 2-4) isolated as PF6 salts. From 3 (X = I) and excess LiCH3 the dimethylcobalt(III) compound [(C5Me4H)Co(CH3)2(PMe3)] (5) is obtained. Treatment of the corresponding trifluoroacetato derivative [(C5Me4H)Co(PMe3)(OCOCF3)2] (6) with PMe3, P(OMe)3, and 1,2-C6H4(PPh2)2 leads, in the presence of NH4PF6, to the formation of the cationic complexes 7-9. The displacement of the two PMe3 ligands in 1 by (Ph2P)2NMe gives the rather unstable chelate compound {(C5Me4H)Co[(Ph2P)2NMe]} (10), which on treatment with NH4PF6 is transformed into the stable complex {(C5Me4H)CoH[(Ph2P)2NMe]}PF6 (11). The structure of 11 has been determined by X-ray diffraction methods.