Organoselenium(II) and selenium(IV) compounds containing 2-(Me2NCH2)C6H4 moieties: solution behavior and solid state structure

The cleavage of the Se–Se bond in [2-(Me2NCH2)C6H4]2Se2 (1) was achieved by treatment with SO2Cl2 (1:1 molar ratio) or elemental halogens to yield [2-(Me2NCH2)C6H4]SeX [X = Cl (2), Br (3), I (4)]. Oxidation of 1 with SO2Cl2 (1:3 molar ratio) gave [2-(Me2NCH2)C6H4]SeCl3 (5). [2-(Me2NCH2)C6H4]SeS(S)CNR2 [R = Me (6), Et (7)] were prepared by reacting [2-(Me2NCH2)C6H4]SeBr with Na[S2CNR2] · nH2O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K[(SPMe2)(SPPh2)N] resulted in isolation of [2-(Me2NCH2)C6H4]Se–S–PMe2N–PPh2S (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 CH2NMe2 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.

Organoselenium(II) compounds containing the 2-(Me2NCH2)C6H4 moiety were prepared and their hypervalent nature was investigated both in solution and the solid state. The molecular structure of the new [2-(Me2NCH2)C6H4]SeCl3, [2-(Me2NCH2)C6H4]SeS(S)CNR2 [R = Me, Et] and [2-(Me2NCH2)C6H4]Se–S–PMe2N–PPh2S derivatives was established by X-ray diffraction. In the crystals, a network of intermolecular X⋯H contacts (X = Cl, I, S) generates different supramolecular architectures, i.e. discrete dimers, polymeric chains or layer structures.Figure optionsDownload as PowerPoint slide