Synthesis and crystal structures of [Ph3PCH2PPh3]I2 dichloromethane disolvate and [Ph3PCH2PPh3](BI4)2

Abstract

Reaction of BI3 with carbodiphosphorane, C(PPh3)2, gives a mixture of the dicationic compounds, methylenebis(triphenylphosphonium) diiodide dichloromethane disolvate, C37H32P22+·2I-·2CH2Cl2 or [Ph3PCH2PPh3]I2·2CH2Cl2(I), methylenebis(triphenylphosphonium) bis(tetraiodoborate), C37H32P22+·2BI4 - or [Ph3PCH2PPh3](BI4)2 (II). Solvents are the source of the protons at the ylidic C atom. The P - C - P angle is 124.1 (2)° for (I) and 121.7 (3)° for (II), while the two P - C bond lengths are 1.804 (4) and 1.807 (5) Å in (I), and 1.817 (5) and 1.829 (5) Å in (II). In the crystal of (I), the protons of the central P - CH2 - P C atom exhibit weak C - H⋯I hydrogen bonds with the respective anions. The anions in turn are linked to the dichloromethane solvent molecules by C - H⋯I hydrogen bonds. In the crystal of (II), one of the BI4- anions is linked to a phenyl H atom via a weak C - H⋯I hydrogen bond.