Chiral sulfur diphosphazanes derived from S-(Ph2P)2N(CHMePh) and its rhodium(I), (III) and iridium(III) complexes. Crystal structures of Ph2P(S)N(CHMePh)PPh2, {Ph2P(S)}2N(CHMePh) and [(Cp*)MCl{η2-P,S-Ph2PNHP(S)Ph2}]BF4, Cp*=η5-C5Me5; M=Rh, Ir

The reaction of S-(Ph2P)2N(CHMePh) with sulfur (1:1 molar ratio) in diethyl ether solution leads to S-Ph2P(S)N(CHMePh)PPh2 (1). The disulphide S-{Ph2P(S)}2N(CHMePh) (2), was obtained when the reaction was carried out in tetrahydrofuran with an excess of sulfur (1:5 molar ratio). 1 reacts with the solvated rhodium (I) complex [Rh(cod)Sx]BF4 to afford the cationic complex [Rh(cod){η2-S,P-Ph2P(S)N(CHMePh)PPh2}]BF4 (3). However, when the above reaction was carried out with 2, cleavage of the CN bond of the ligand occurred, to yield the complex [Rh(cod)(η2-S,S-{Ph2P(S)}2NH)]BF4 (4). Reactions of 1 with the fragments of Rh (III) and Ir (III) [Cp*MClSx]BF4 lead to cleavage of the CN bond of the ligand yielding cationic complexes, [(Cp*)MCl{η2-P,S-Ph2PNHP(S)Ph2}]BF4 (M=Rh, 5; Ir, 6]. Crystal structures of 1, 2, 5 and 6 have been determined by X-ray diffraction methods. Compounds 1 and 2 crystallize in the same space group P2(1)2(1)2(1). The molecular structure of 1 shows a nearly trigonal planar nitrogen atom bound to two different phosphorus atoms and to the chiral carbon atom. Compound 2 acquires a twisted conformation with the two sulfur atoms adopting mutually trans positions with respect to the PNP backbone.