Diphenyl[(phenylsulfanyl)methyl]-λ5-phosphanethione

The title compound, C19H17PS2, results from the direct deprotonation of diphenylmethylphosphine sulfide and subsequent reaction with diphenyl disulfide. The C—P and C—S bond lengths of 1.8242 (18) and 1.8009 (18) Å, respectively, of the central P—C—S linkage are comparable to those found in the sulfonyl analogue, but are considerably longer than those reported for the dimetallated sulfonyl compound. The dihedral angle between the benzene rings of the diphenylmethyl moiety is 69.46 (7)°. No distinct intermolecular interactions are present in the crystal structure.


Comment
Methylene compounds with two anion-stabilizing substituents, such as phosphonium or sulfonyl moieties, have found special interest as precursors for the corresponding dimetallated methandiides (Kasani et al., 1999;Ong et al., 1999;Cantat et al., 2006;Cooper et al., 2010). These dianions were found to be excellent ligands for the preparation of carbene complexes exhibiting a unique electronic structure (Gessner et al., 2013). They allowed the synthesis of a variety of different complexes with early and late transition metals, but also with lanthanides and actinides (Cavell et al., 2001;Cantat et al., 2008;Harder, 2011;Liddle et al., 2011).
As part of our studies on the synthesis of novel methandiides for the preparation of carbene complexes, we have developed a ligand and its dianionic analogue with a thiophosphoryl and sulfonyl sidearm (Schröter & Gessner, 2012).
Thereby, the synthesis of a protonated precursor is best achieved via a two-step synthesis, with the first step being the lithiation of diphenylmethylphosphine sulfide and its reaction with diphenyl disulfide (Becker & Gessner, 2014a,b). This procedure furnishes the title compound, C 19 H 17 PS 2 , in good yield. Oxidation of the sulfide to the sulfone gives way to the final ligand (Gessner, 2012).
The bond lengths and angles in the title compound are comparable to the sulfonyl analogue, but deviate considerably from the dimetallated compound (Schröter & Gessner, 2012). These differences are most pronounced in the P-C-S backbone. While the title compound features C-P and C-S distances of 1.8242 (18) and 1.8009 (18) Å, respectively, the sulfonyl substituted dianion shows C-P av distances shortened by ≈ 7% [1.710 (4) Å] and C-S distances shortened by ≈ 11% [1.614 (3) Å] (Schröter & Gessner, 2012). Additionally, the P-C-S angle experiences a widening from 107.7 (1)° in the title compound to 121.4 (2)° in the methandiide. This is the result of a change in the hybridization of the central carbon atom from sp 3 in the title compound to sp 2 in the methandiide.
No distinct intermolecular interactions (such as C-H···S interactions) are present in the crystal structure of the title compound.

Refinement
The H atoms were refined on a riding model approximation in their ideal geometric positions with C-H = 0.95 Å for C-H(aromatic) and 0.99 for CH 2 atoms, respectively, with U iso (H) = 1.2U eq (C).

Figure 1
The molecular structure of the title compound. Displacement parameters are drawn at the 50% probability level. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.