In order to study the properties of sulfur coordinated metal centres, the chromium and tungsten complexes [Cr(NO)(µ-′S4′)]2 (4), (NR4)2[W(NO)2(′S2′)2] (1) (R = Me (la), n-Bu (lb)), [W(NO)2(′S4′)] (2), [µ-O{W(NO)(′S4′)}2] (3) and [W(NPR3)(NO)(′S4′)] (5) (R = Me (5a), Et (5 b)) were synthesized (′S2′2- = 1.2-benzenedithiolate(2-); ′S4′2- = 1.2-bis(2-mercaptophenylthio)ethane(2-)). la and lb result from the reductive nitrosylation of Li2[W(′S2′)3] which was prepared by reduction of [W(′S2′)3] with n-BuLi. la was also obtained from [W(NO)2(Cl)2]n, ′S2′2- and NMe4+. Alkylation of la or lb by 1.2-dibromoethane yields 2, whose X-ray structure analysis shows that W is pseudooctahedrally coordinated by two trans thiolato S, two cis thioether S and two cis N atoms of linear W-NO groups. 2 was also obtained from [W(NO)2(CH3CN)4](BF4)2 or [W(NO)2(Cl)2]n and ′S4′2--. The reaction of [W(NO)2(Cl)2]n yielded the dinuclear oxo-bridged complex 3 as a by-product in small amounts. In preparative amounts, 3 was synthesized by hydrolysis of [W(Cl)(NO)(′S4′)]. In contrast to the analogous Mo complex, 2 does not react with N2H4; with the ligands PMe3 and PEt3, it gives the corresponding phosphiniminato complexes 5 and free phosphineoxides OPR3. In order to compare the [M(NO)2(′S4′)] complexes (M = Cr, Mo, W), the structure of [Cr(NO)2(′S4′)] was determined by X-ray structure analysis. The Cr complex exhibits the same molecular coordination geometry as 2. While growing crystals of [Cr(NO)2(′S4′)], the dinuclear Cr complex 4 was also formed. Its X-ray structure analysis shows each of the Cr centres to be coordinated pseudooctahedrally by five sulfur donors and one nitrosyl N donor. 4 was also obtained by the reaction of [Cr(CO)4(nor)] with ′S4′2- and NOBF4.
Synthesis of chloro and methyl imido cyclopentadienyl molybdenum and tungsten complexes. X-ray molecular structures of WCp*Cl3(NtBu), MoCp*ClMe2(NtBu) and WCp*ClMe2(NtBu)