An intermolecular Lewis pair based on tin acid and phosphonium ylide base functions

The tin-containing Lewis acid group (C2F5)3Sn was combined with a phosphonium ylide as base function in one molecule: o-[(C2F5)3Sn]-C6H4(Ph)2PCMe2. It was prepared by reacting the ortho-lithiated triphenylphosphoniumdimethylmethylide (o-Li-C6H4)(Ph)2PCMe2 with the stannyl chloride (C2F5)3SnCl to afford o-[(C2F5)3Sn]-C6H4(Ph)2PCMe2 in 86 % yield. It forms a ring structure with a bond between tin and the ylidic carbon atom both in solution and in the solid state and can thus be considered as a hidden frustrated Lewis pair. The title compound is unreactive towards H2, CO2, CS2, PhNCO and decomposes in the presence of SO2 or NH3. However, it is active in the catalytic reduction of CO2 with pinacolborane, H-BPin. The title compound reacts slowly with H-BPin in an unselective reaction from which a reduction product with cleaved C2F5 group, the phosphonium stannate (II) o-[(C2F5)2Sn]-C6H4(Ph)2PCHMe2, could be obtained in small amounts.