Metallathiirenes. 3.¹ Thiocarbamoyl and Alkoxythiocarbonyl Complexes of Molybdenum(II) and Tungsten(II)

Abstract

Synthetic routes to thiocarbamoyl (thiocarboxamide) complexes of divalent molybdenum and tungsten are reported: The reaction of fac-[Mo(CO)3(NCMe)3] with N,N-dimethyl thiocarbamoyl chloride (Me2NC(S)Cl) at low temperature provides a thermally labile intermediate (1) presumed on the basis of subsequent transformations to be [Mo(η2-SCNMe2)Cl(CO)3(NCMe)]. Reactions of 1 with K[HB(pz)3] (pz = pyrazol-1-yl), NaC5H5, bipy, or tmeda provide the complexes [Mo(η2-SCNMe2)(CO)2{HB(pz)3}] (2), [Mo(η2-SCNMe2)(CO)2(η-C5H5)] (3), [Mo(η2-SCNMe2)Cl(CO)2(bipy)] (4), and [Mo(η2-SCNMe2)Cl(CO)2(tmeda)] (5), respectively. The complex cis,cis,trans-[Mo(η2-SCNMe2)Cl(CO)2(PPh3)2] (6) results from the oxidative 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 also be obtained from reaction of (i) K[Mo(CO)3{HB(pz)3}] with Me2NC(S)Cl; (ii) [Mo(CO)3(η6-C7H8)] 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(CO)3(NCMe)3] or [Mo(CO)3(η6-C7H8)] with ClC(S)OR (R = C6H4Me-4, C6H5) and K[HB(pz)3] provides the complexes [Mo(η2-SCOR)(CO)2{HB(pz)3}] [R = C6H4Me-4 (7a), C6H5 (7b)]. Attempts to prepare a mononuclear thiocarbamoyl complex by addition of elemental sulfur or propene episulfide to the aminomethylidyne complex [Mo(⋮CNiPr2)(CO)2{HB(pz)3}] (8) were unsuccessful; however addition of [Fe2(CO)9] to 8 provided the thermally unstable complex [MoFe(μ-CNiPr2)(CO)5{HB(pz)3}] (9), which reacts with sulfur to provide the heterobimetallic bridging thiocarbamoyl complex [MoFe(μ-SCNiPr2)(CO)5{HB(pz)3}] (10). Treating fac-[W(CO)3(NCMe)3] sequentially with Me2NC(S)Cl and K[HB(pz)3] provided [W(η2-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).