Polysulfido Chain in Binuclear Zinc(II) Complexes.

The synthesis and a detailed reactivity study of a binuclear zinc(II) bis(benzenethiolate) complex, [Zn 2 (BPMP)(SPh) 2 ] + ( 4 ), and an unprecedented binuclear zinc(II) pentasulfido complex, [Zn 2 (BPMP)(μ 2 -S 5 )] + ( 6 ), are presented. While one-electron oxidation of the coordinated benzenethiolate ligands in 4 by Cp 2 Fe + produces diphenyl disulfide and [Zn 2 (BPMP)(μ 2 -OH)] 2+ ( 5 ), a two-electron redox reaction between coordinated benzenethiolate ligands in 4 and elemental S (S 8 ) generated diphenyl disulfide and the binuclear zinc(II) pentasulfido complex 6 . Complex 6 features a chelating, dianionic, pentasulfido (S 5 2- ) chain and can consume up to a maximum of 3 equiv of PPh 3 to generate Ph 3 PS and 5 , while the reaction of 6 with 1 equiv of diphenylphosphinoethane allowed the isolation of [Zn 2 (BPMP)(μ 2 -S 4 )] + ( 7 ). A proteolysis reaction of the coordinated S 5 2- chain in 6 with fluoroboric acid (HBF 4 ), benzoic acid (PhCOOH), and thioacetic acid (MeCOSH) generates the complexes [Zn 2 (BPMP)(MeCN) 2 ] 3+ ( 1 ), [Zn 2 (BPMP)(μ 2 -PhCOO) 2 ] + ( 8 ), and [Zn 2 (BPMP)(μ 2 -SCOMe) 2 ] + ( 9 ), respectively, while the protonated S 5 2- chain liberates S 8 and hydrogen sulfide (H 2 S). Finally, the transfer of the coordinated benzenethiolate ligands in 4 and the S 5 2- chain in 6 to selected organic compounds, namely, PhCH 2 Br and PhC(O)Cl, for the generation of various organosulfur compounds is demonstrated.