Transition metal complexes with sulfur ligands Part XCIII. Synthesis, structure and reactivity of [Mo IV(μ-S)(‘ buS 4’)] 2 (‘ buS 4’ 2−=1.2-bis(di(t-butyl)-2-mercaptophenylthio)ethane(2−))

Abstract

In search for model compounds of the active centers of enzymes containing Mo we obtained in DMF the binuclear complexes [MoS(‘S 4’)] 2 ( 1) (‘S 4’ 2−=1.2-bis(2-mercaptophenylthio)ethane(2−)) and [Mo(μ-S)(‘ buS 4’)] 2 ( 2) (‘ buS 4’ 2−=1.2-bis(3.5-di(t-butyl)-2-mercaptophenylthio)ethane(2−)) from either (a) H 2S and [MoCl 2(L)] or (b) H 2S, [MoCl 4(MeCN) 2] and L-H 2 (L‘S 4’, ‘ buS 4’). According to method (b) [MoS(‘N 2H 2S 2’)] 2 ( 3) (‘N 2H 2S 2’ 2−=1.2- bis(2-mercaptophenylthio)ethane(2−)) could also be prepared, being isolated as the solvate 3·2DMF. [Mo(μ- S)(‘ buS 4’)] 2·6CD 2Cl 2 ( 2·6CD 2Cl 2) was obtained as single crystals and characterized by X-ray structure analysis (monoclinic space group P2 1/ c, Z=2, a=1607.4(16), b=1540.3(14), c=1836.6(14) pm, β=111.43(6)°, R ( Rw)=0.065 (0.056)). 2 contains two enantiochiral [Mo(‘ buS 4’)] fragments which are connected via two sulfido bridges and one MoMo bond such that the Mo centers become seven-coordinate. 2 is electrochemically redox active, showing two oxidation and reduction waves each in the cyclic voltammogram (CH 2Cl 2), but does not react with either N 2H 4 and O 2 or CO and PMe 3. Attempts to prepare anionic [Mo(‘N 2H 2S 2’)] complexes with sulfido ligands led to NBu 4Cl·(NBu 4) 2[Mo 3(μ 3-S)(μ 2-S 2) 3S 6] ( 4) as the minor by-product. 4 was characterized by X-ray structure analysis (monoclinic space group P2 1/ c, Z=4, a=1274.4(7), b=1322.6(6), c=4143.8(15) pm, β=97.30(4)°, R ( R w)=0.098 (0.078)).