eta(2)-alkynyl and vinylidene transition metal complexes. 7. Hydroamination of neutral tungsten-vinylidene complexes

Primary and secondary amines 2a-d have been found to react in THF at room t emperature with the vinylidene complexes [W(=C=CHR)(eta (5)-C5H5)(CO)(NO)] (R = C(CH3)(3) (1), R = Si(CH3)C(CH3)(3) (4)), affording the aminocarbene d erivatives [W{=C((NRR2)-R-1)CH2C(CH3)(3)}(eta (5)-C5H5)(CO)(NO)] and [W{=C( (NRR2)-R-1)CH2Si(CH3)(2)C(CH3)(3)}(eta (5)-C5H5)(CO)(NO)] (R-1 = H, R-2 = n -C4H9 (3a, 5a); R-1 = H, R-2 = CH(CH3)(2) (3b, 5b); R-1 = H, R-2 = C(CH3)(3 ) (3c, 5c); R-1 = R-2 = (CH2)(4) (3d, 5d)). At short reaction time the nucl eophilic addition of both primary and secondary amines to 1 occurs at the c arbonyl carbon atom, leading stereoselectively to the thermodynamically les s stable eta (2)-carbamoyl-(Z)-vinyl complexes [W{sigma-(Z)-CH=CHC(CH3)(3)} -{eta (2)-C(O)(NRR2)-R-1} (eta (5)-C5H5)(NO)] (R-1 = H, R-2 = n-C4H9 (6a); R-1 = H, R-2 = CH(CH3)(3) (6b); R-1 = H, R-2 = C(CH3)(3) (6c); R-1 = R-2 = (CH2)(4) (6d)). At higher amine concentration and prolonged reaction time 6 a-d form the corresponding aminocarbene complexes 3a-d. The structure of 6b has been authenticated by a single-crystal X-ray diffraction analysis.