Thiolate coordination in binuclear oxomolybdenum(V) complexes. The x-ray crystal structures of the alkylammonium salts of [Mo2O2(OCH3)(SCH2CH2CH2S)3]− and [Mo2O2(SCH2CO2)4]2−

Abstract Reaction of [ n -Bu 4 N] 2 [Mo 2 O 7 ] with propane-1,3-dithiol in methanol yields the triply-bridged binuclear complex [ n -Bu 4 N][Mo 2 O 3 (OCH 3 )(SCH 2 CH 2 CH 2 S) 3 ] ( 1 ). Complex 1 exhibits the confacial bioctahedral geometry characteristic of this class of complexes. In contrast, the reaction of [ n -Bu 4 N] 4 [Mo 8 O 26 ] with 2-mercaptoacetic acid and triethylamine in methanol results in the isolation of a complex [Et 3 NH] 2 [Mo 2 O 2 (SCH 2 CO 2 ) 4 ] ( 2 ), representing the first example of a new class of binuclear molybdenum(V) species. The structure is characterized by a ‘ trans -planar’ [Mo 2 O 2 S 2 (thiolate)] 4+ core and an unusually long Mo ⋯ Mo distance of 3.078(1) A. Crystal data. Complex 1 : triclinic space group P 1 , a = 9.310(2), b = 11.328(2), c = 19.954(3) A, α = 74.93(1), β = 78.19(1), γ = 81.53(1)°, V = 1979.2(10) A 3 , Z = 2, D calc , = 1.369 g cm 3− ; structure solution and refinement based on 5292 reflections, R = 0.0570. Complex 2 : monoclinic space group P 2 1 / n , a = 10.861(4), b = 13.559(4), c = 11.011(4) A, β = 104.14(2)°, V = 1572.1(11) A 3 , Z = 2, D calc , = 1.664 g cm −3 ; 2133 reflections, R = 0.0560.