Organoselenium(II) and selenium(IV) compounds containing 2-(Me 2NCH 2)C 6H 4 moieties: solution behavior and solid state structure

Abstract

The cleavage of the Se–Se bond in [2-(Me 2NCH 2)C 6H 4] 2Se 2 ( 1) was achieved by treatment with SO 2Cl 2 (1:1 molar ratio) or elemental halogens to yield [2-(Me 2NCH 2)C 6H 4]SeX [X = Cl ( 2), Br ( 3), I ( 4)]. Oxidation of 1 with SO 2Cl 2 (1:3 molar ratio) gave [2-(Me 2NCH 2)C 6H 4]SeCl 3 ( 5). [2-(Me 2NCH 2)C 6H 4]SeS(S)CNR 2 [R = Me ( 6), Et ( 7)] were prepared by reacting [2-(Me 2NCH 2)C 6H 4]SeBr with Na[S 2CNR 2] · nH 2O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K[(SPMe 2)(SPPh 2)N] resulted in isolation of [2-(Me 2NCH 2)C 6H 4]Se–S–PMe 2 N–PPh 2 S ( 8). The compounds were characterized by solution NMR spectroscopy ( 1H, 13C, 31P, 77Se, 2D experiments). The solid-state molecular structures of 2, 4– 8 were established by single crystal X-ray diffraction. All compounds are monomeric, with the N atom of the pendant CH 2NMe 2 arm involved in a three-center-four-electron N⋯Se–X (X = halogen, S) bond. This results in a T-shaped coordination geometry for the Se(II) atom in 2, 4, 6– 8. In 5, the Se(IV) atom achieves a square pyramidal coordination in the mononuclear unit. Loosely connected dimers are formed through intermolecular Se⋯Cl interactions (3.40 Å); the overall coordination geometry being distorted octahedral. In all compounds hydrogen bonds involving halide or sulfur atoms generate supramolecular associations in crystals.