Aminomethylene complexes of molybdenum(IV) and tungsten(IV) bearing 1,2-dithiolato ligands

The syntheses, spectroscopic data and the structures of molybdenum(IV) and tungsten(IV) aminomethylene complexes bearing 1,2-dithiolato ligands are pr esented. Oxidative decarbonylation of Cp*(CO)(2)M drop CNEt2 (1a,b) (a: M = Mo; b: M = W; Cp* = pentamethylcyclopentadienyl) with PhICl2 affords the a minocarbyne complexes cis-Cp*(Cl)(2)(CO)M drop CNEt2 (2a,b), which react wi th the 1,2-dithiolates Na-2(mnt) x DMF, (mnt(2-) = 1,2-dicyanoethene-1,2-di thiolate), Li-2(bdt) (bdt(2-)= 1,2-benzenedithiolate) and Li-2(Mebdt) (Mebd t(2-) =4-methyl-1,2-benzenedithiolate) to afford the substitution products Cp*(mnt)(CO)M drop CNEt2 (3a,b), Cp*(bdt)(CO)M drop CNEt2 (4a,b) and Cp*(Me bdt)(CO)W drop CNEt2 (5b), respectively. Treatment of 3b with HCl yields, a fter elimination of CO, the 16-electron aminomethylene complex Cp*(Cl)(mnt) W=C(H)NEt2 (6b). Addition of HCl to the M-C triple bond of complexes 4a,b a nd 5b, affords the 18-electron aminomethylene complexes Cp*(Ci)(bdt)(CO)M=C (H)NEt2 (7a,b) and Cp*(Cl)(Mebdt)(CO)W=C(H)NEt2 (8b), which upon heating lo se carbon monoxide to afford the 16-electron aminomethylene complexes Cp*(C l)(bdt)M=C(H)NEt2 (9a,b) and Cp*(Cl)(Mebdt)W=C(H)NEt2 (10b), respectively. An alternative approach to 9b offers the nucleophilic substitution reaction of Cp*(Cl)(3)W=C(H)NEt2 with Li-2(bdt). Complexes 2a-10b have been fully c haracterized and the crystal structures of the complexes 3b, 6b and 9b are discussed. 2001 Elsevier Science B.V. All rights reserved.