Reactivity of alkynes toward M-η2-CS2 metal complexes. 3. The coupling products obtainable with bis(cyclopentadienyl)molybdenum fragments and their relative stability

Françoise Conan, Jean Sala-Pala, Jacques E. Guerchais, Jing Li, Roald Hoffmann, Carlo Mealli, René Mercier, Loïc Toupet

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10 Citations (Scopus)

Abstract

[Cp2Mo-η2-CS2] (1) is shown to react with one, two, and three molecules of activated alkynes. The nature of the different coupling products and the reaction conditions are described. In particular, while CF3O≡CCF3 reacts with 1 to give the metallacycle derivative [Cp2MoC(S)SC(R)=C(R) ] (2, R = CF3), the reaction of 1 with CO2MeC≡CCO2Me affords two isomers: 3, the analogue of 2 with R = CO2Me, and [Cp2 MoSC(S)C(R)=CR] (4, R = CO2Me). The complexes obtained from the reaction of HC≡CCN with 2 and 3, [CpMo{C5H4C(SCH=CHCN)SC(R)=CR}] (5, R = CF3; 6, R = CO2Me), correspond to a new type of combination of CS2 with two alkynes. Direct reaction of 1 with HC≡CCN does not yield an analogue of complexes 5 and 6 but gives depending on the experimental conditions either compound 7 [Cp2Mo-(C10H3N3S2)], the first example of a complex in which CS2 is combined with three molecules of alkyne, or [Cp2Mo(η2-CS3)] (8) and [S((Z)-CH=CHCN)2] (9). The crystal and molecular structures of complexes 2, 4, 6, and 7 have been determined by single-crystal X-ray diffraction studies. 2 crystallizes in the monoclinic space group P21/c with a = 13.032 (2) Å, b = 8.066 (2) Å, c _= 18.155 (2) Å, β = 124.70 (1)°, U = 1569 (1) Å3, and Z = 4. 4 crystallizes in the triclinic space group P1 with a = 7.662 (4) Å, b = 14.661 (5) Å, c = 15.414 (4) Å, α = 96.00 (3)°, β = 96.19 (3)°, γ = 90.79 (4)°, U = 1711.3 (5) Å3, and Z = 4. 6 crystallizes in the monoclinic space group P21/c with a = 10.246 (4) Å, b = 15.245 (9) Å, c = 15.140 (8) Å, β = 103.89 (5)°, U = 2296 (2) Å3, and Z = 4. 7 crystallizes in the orthorhombic space group Pbca with a = 22.089 (5) Å, b = 10.699 (2) Å, c = 15.660 (3) Å, U = 3701 (2) Å3, and Z = 8. Extended Hückel calculations and qualitative MO theory are used to analyze the electronic features of the most simple models obtainable from the coupling of CS2 with an alkyne molecule, namely, Cp2MoC(S)SC(R)=C(R) (complexes 2 and 3) and Cp2MoSC(S)C(R)=C(R) (complex 4). The study illustrates the major orbital effects and points out that in the course of the coupling reaction to form the latter complex, the metal may undergo an oxidation state change.

Original languageEnglish
Pages (from-to)1929-1941
Number of pages13
JournalOrganometallics
Volume8
Issue number8
Publication statusPublished - 1989

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

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