Cumulated double bond systems as ligands : X. N-sulfinylaniline complexes of rhodium(I) and iridium(I) of the type [MCl(PR3)2L] in which L is coordinated via the π-NS and via the sulfur atom respectively; crystal and molecular structure of [RhCl(P-i-Pr3)2(4-MeC6H4NSO)]; determination of the 1J(103Rh15N) by 15N NMR spectroscopy

Abstract Each of the compounds [MCl(Pr 3 ) 2 (ArylNSO)] (M = Rh I , Ir I ; R = i-Pr, Cy: Aryl = C 6 H 5 , 4-MeC 6 H 4 , 4-ClC 6 H 4 , 2,4,6-Me 3 C 6 H 2 appears to exist as two isomers both in the solid state and in solution. The molecular and single crystal structure of one of the isomers of [RhCl(P-i-Pr) 3 ) 2 (4-Me 6 H 4 NSO)] shows that the N -sulfinylaniline ligand is in the cis -configuration and coordinated to the rhodium atom via the sulfur-atom. The ligand lies in a plane which includes the rhodium atom and is in agreement with the Rh-S distance of 2.10 A. IR results of the compounds (solid and solutions), 21 P NMR data and 15 N NMR of a 15 N labelled compound, which yielded a 103 Rh 15 N coupling constant of 15.5 Hz, show that in the second isomer the N -sulfinylaniline ligand is probably bonded to the metal atom via the π-NS bond. The ratio of the metal-π-NS bonded isomer and the metal-S bonded isomer decreases in the order Aryl = 4-ClC 6 H 4 > C 6 H 5 > 4-MeC 6 H 4 ; R = i-Pr > Cy and M = Rh > Ir. The interconversion of the two isomers is intramolecular and becomes observable on the 31 P NMR time scale at about 40° C for M = Rh. In the case of [Ir(P-i-Pr 3 ) 2 (4-MeC 6 H 4 NSO)], cyclometallation of the sul- finylaniline is observed via the ortho -carbon atom, whereas cyclometallation via P-i-Pr 3 is observed when the ortho -positions are blocked by methyl groups, e.g. when L = 2,4,6-Me 3 C 6 H 2 NSO.