INSERTION CHEMISTRY OF HTC(CO)(3)(PPH(3))(2)

The technetium(I) monohydride complex HTc(CO)(3)(PPh(3))(2) (1) has been prepared by treatment of the trihydride H3Tc(PPh(3))(4) with CO(g) in benzene. Reaction of 1 with [p-(t)Bu(C6H4)N-2]PF6 affords [Tc(CO)(3)(NHN(p-(t)Bu(C6H4))(PPh(3))(2)]PF6 (2a) in 67% yield. The molecular structure for 2a was determined by X-ray diffraction to have the following parameters: space group P2(1)/n, a = 14.030(3) Angstrom, b = 14.123(3) Angstrom, c = 25.227(5) Angstrom, beta = 96.09(2)degrees, monoclinic, and Z = 4. Addition of 1 equiv of 1,8-diazabicyclo[5.4.0]undecene to MeCN solutions of 2a gives the neutral diazene complex, c(CO)(3)(NN(p-(t)Bu(C6H4))(PPh(3))(2) (2b). Treatment of 1 with the heterocumulenes CS2 and N(CH3)CS, yields Tc(CO)(2)(eta(2)-S2CH)(PPh(3))(2) (3) and Tc(CO)(2)(eta(2)-N(CH3),SCH)(PPh(3))(2) (4). Complex 1 also reacts with electron-deficient acetylenes. When 1 is treated with 1 equiv of dimethylacetylenedicarboxylate, Tc(CO)(2)[-C(CO(2)Me)=CH(C(O)OMe)](PPh(3))(2) (5) is obtained. In 5, the acetylene ligand is coordinated through both a vinylic carbon atom and a carbonyl oxygen atom forming a five-membered chelate ring. Treatment with the less electrophilic acetylene methyl propiolate affords Tc(CO)(3)[-C(CO(2)Me)=CH2](PPh(3))(2) (6) in 57% yield.