The O,C,O-Coordinating Pincer-Type Ligand {2,6-[P(O)(OEt)₂]₂-4-t-Bu-C₆H₂}⁻ in Organotin Chemistry. Halide Exchange, Cyclization, and Novel Coordination Mode

Reactions in solution of the hypercoordinated organotin chlorides {2,6-[P(O)(OEt)2]2-4-t-Bu-C6H2}SnCl2X (X = Ph, Cl) with fluoride ions have been studied using temperature-dependent 119Sn and 31P NMR spectroscopy and electrospray mass spectrometry. The syntheses and molecular structures of the novel intramolecularly coordinated diorganotin difluoride {2,6-[P(O)(OEt)2]2-4-t-Bu-C6H2}SnF2Ph·0.5H2O (1), the heterocyclic compound {[1(Sn),3(P)-PhClSnOP(O)(OEt)-5-t-Bu-7-P(O)(OEt)2]C6H2}2 (3), and the monoorganotin difluoride hydroxide {{2,6-[P(O)(OEt)2]2-4-t-Bu-C6H2}SnF2OH}2 (6) are reported. In the crystal lattice, compound 1 forms an adduct composed of two tin moieties and a water molecule which are linked via F···H−O−H···F hydrogen bridges. The intramolecularly coordinated benzoxaphosphastannole derivative 3 is formed by intramolecular cyclization of {2,6-[P(O)(OEt)2]2-4-t-Bu-C6H2}SnCl2Ph with elimination of ethyl chloride and dimerization. The organotin difluoride hydroxide derivative 6 is a dimer in the solid state as a result of intermolecular hydroxide bridges. Also present are intramolecular Sn−O−H···OP hydrogen bonds. The configuration at tin is best described as a monocapped octahedron.