Complexes of molybdenum-(II) and -(IV) and tungsten(II) with sterically hindered thiolate ligands. Synthesis, reactivity, and X-ray crystal structures of [PPH4][Mo(SC6H2Pri3,-2,4,6)3(CO)2] and [Mo(NNPh)(SC6H2Pri3-2,4,6)3(NCMe)]

Abstract

[MBr₂(CO)₄](M = MO or W) react with thiolate anions SR^– to give the anions [M(SR)₃(CO)₂]^–(SR = SC₆H₂Prⁱ₃-2,4,6, SC₆H₃Prⁱ₂-2,6, SC₆H₂Br-4-Prⁱ₂-2,6, SC₆H₂Me_3^–2,4,6, SC₆F₅). The complex [pph₄][Mo(SC₆H₂Prⁱ₃-2,4,6)₃(CO)₂] crystallises in space group P with a= 13.451 (2), b= 14.229(2), c= 19.862(3)Å, α= 96.11(1), β= 94.11(1), γ= 111.04(1)°, and Z= 2. Structure analysis based on 2 939 reflections with I₀ < 3.0σ(I₀) refined to R= 0.0755. The anion has a trigonal-bipyramidal structure with axial co-ligands. The complexes [M (SR)₃(CO)₂]^– react with CO to give [M(SR)₃(CO)₃]^–. [Mo(SC₆H₂Prⁱ₃-2,4,6)₃(CO)₂]^– reacts with neutral donors L to give [Mo(SC₆H₂Prⁱ₃-2,4,6)₃(CO)L]^–(L = MeCN, Bu^tCN, PMe₂Ph, or Bu^tNC) and with [N₂Ph][BF₄] in MeCN to give [Mo(NNPh)(SC₆H₂Prⁱ₃-2,4,6)₃(NCMe)]. This complex crystallises in space group Pnma with a= 9.962(3), b= 21.002(4), c= 27.646(4)Å, and Z= 4. Structure analysis based on 1 772 reflections with I₀ > 3σ(I₀) refined to R= 0.075. The NNPh and MeCN ligands occupy the axial sites of a trigonal bipyramid with the thiolates equatorial.