Metallathiirenes. 3. Thiocarbamoyl and alkoxythiocarbonyl complexes of molybdenum(II) and tungsten(II)

Synthetic routes to thiocarbamoyl (thiocarboxamide) complexes of divalent m olybdenum and tungsten are reported: The reaction of fac-[Mo(CO)(3)(NCMe)(3 )] with N,N-dimethyl thiocarbamoyl chloride (Me2NC(=S)CI) at low temperatur e provides a thermally labile intermediate (1) presumed on the basis of sub sequent transformations to be [Mo(eta (2)-SCNMe2)-Cl(CO)(3)(NCMe)]. Reactio ns of 1 with K[HB(pz)(3)] (pz = pyrazol-1-yl), NaC5H5, bipy, or tmeda provi de the complexes [Mo(eta (2)-SCNMe2)(CO)(2){HB(pz)(3)}] (2), [Mo(eta (2)-SC NMe2)(CO)(2)(eta -C5H5)] (3), [Mo(eta (2)-SCNMe2)Cl(CO)(2)(bipy)] (4), and [Mo(eta (2)-SCNMe2)Cl(CO)(2)(tmeda)] (5), respectively. The complex cis, ci s, trans-[Mo(eta (2)-SCNMe2)Cl(CO)(2)(PPh3)(2)] (6) results from the oxidat ive addition of Me2NC(=S)Cl to [Mo(NCMe)(2)(CO)(2)(PPh3)(2)] and is one of two isomers obtained from the reaction of 1 with PPh3. The complex 2 may al so be obtained from reaction of (i) K[Mo(CO)(3){HB(pz)(3)}] with Me2NC(=S)C l; (ii) [Mo(CO)(3)(eta (6)-C7H(8))] With Me2NC(=S)Cl and K[HB(pz)(3)]; and (iii) K[HB(pz)(3)] with either 5 or 6, Sequential treatment of either [Mo(C O)(3)-(NCMe)(3)] or [MO(CO)(3)eta (6)-C7H8)] With ClC(=S)OR (R=C6H4Me-4, C6 H5) and K[HB(pz)(3)] provides the complexes [Mo(eta (2)-SCOR)(CO)(2){HB(pz) (3)}] [R = C6H4Me-4 (7a), C6H5 (7b)]. Attempts to prepare a mononuclear thi ocarbamoyl complex by addition of elemental sulfur or propene episulfide to the aminomethylidyne complex [Mo(equivalent to (CNPr2)-Pr-i)(CO)(2){HB(pz) (3)}] (8) were unsuccessful; however addition of [Fe-2(CO)(9)] to 8 provide d the thermally unstable complex [MoFe(mu -(CNPr2)-Pr-i)(CO)(5){HB(pz)(3)}] (9), which reacts with sulfur to provide the heterobimetallic bridging thi ocarbamoyl complex [MoFe(mu -(SCNPr2)-Pr-i)(CO)(5){HB(Pz)(3)}] (10) Treatin g fac-[W(CO)(3)(NCMe)(3)] sequentially with Me2NC(=S)Cl and K[HB(pz)(3)] pr ovided [W(eta (2)-SCNMe2)(CO)(2){HB(pz)(3)}] (11); however replacing Me2NC( =S)Cl with ClC(=S)OC6H4Me-4 led to [WCl(CO)(3){HB(pz)(3)}] (12).