Hypercoordinated triorganotellurium(IV) derivatives of chalcogen-centred organophosphorus ligands

Abstract

Triorganotelluronium complexes of type [{2-(Me2NCH2)C6H4}nPh3-nTe]L [(L = S2PMe2, n = 3 (1), 1 (2); L = (EPPh2)2N, E = S, n = 3 (3); E = Se, n = 3 (4), 2 (5), 1 (6) and L = (SPPh2)(O2SC6H4CH3-4)N, n = 3 (7), 2 (8), 1 (9)] were obtained by salt metathesis reactions between triaryltelluronium halides of type [{2-(Me2NCH2)C6H4}nPh3-nTe]X (X = Cl, Br) and the alkali metal salt of the corresponding organophosphorus acid in a 1:1 molar ratio. The new ionic species were characterized by multinuclear NMR spectroscopy and mass spectrometry. The NMR spectra show similar resonances for each series of triorganotelluronium complexes (1 and 2, 3–6 and 7–9). The 1H NMR spectra suggest intramolecularly coordinated pendant arms in solution for compounds bearing two or three 2-(Me2NCH2)C6H4 groups. Single-crystal X-ray diffraction studies revealed strong N→Te intramolecular interactions in compounds 2, 4, 6 and 7, which result in hypercoordinated triorganotelluronium(IV) cations with different distorted coordination geometries. Further secondary bonding interactions (S⋅⋅⋅Te in 2 and Se⋅⋅⋅Te in 6) lead to cation–anion associations, while H⋅⋅⋅E (E = S, Se) contacts between cations and anions resulted in different supramolecular networks in 2, 4 and 6 and in discrete cation–anion pairs in 7.