Alkylation-Induced O-Atom Rearrangement in Nickel S-Oxygenates

Reactions of organic halides MeI and Br(CH 2 ) 3 Br with square planar nickel complexes of tetradentate N 2 SS‘ or N 2 S‘ 2 ligands (S‘ = RS( O)) have been explored for their potential to direct alkylation of metallosulfoxide sulfur and yield metal-bound organic sulfoxides. In fact, as established by spectroscopic and electrochemical signatures, isolated products were characterized as the result of O-atom rearrangements or transfers leading primarily to metallosulfones (Ni−SO 2 R) and metallothiolates (Ni−SR) (which were subsequently alkylated to nickel-bound thioethers). Proposed intermediates in the reactions of the monosulfoxide, Ni-4*, N -(2-mercapto-2-(methylpropyl))- N ‘-(2-sulfenato-2-(methylpropyl))-1,5-diazacyclooctanenickel(II) and the bis-sulfoxide, Ni-5*, N, N ‘-bis(2-sulfenato-2-(methylpropyl))-1,5-diazacyclooctanenickel(II), with 1,3-dibromopropane include S-bound R‘S−OR moieties resulting from ring closure of the pendant alkyl bromide on the nucleophilic sulfoxide oxygen. X-ray crystal structures of N -(sulfinato-2-(methylpropyl))- N ‘-(2-thia-2-(methylpropyl))-1,5-diazacyclooctanenickel(II) iodide and a bimetallic composed of two units of N -(2-mercapto-2-(methylpropyl))- N ‘-(2-sulfinato-2-(methylpropyl))-1,5-diazacyclooctanenickel(II) linked by (CH 2 CH 2 CH 2 ) are reported.