metal-organic papers m1702 Kirsten et al.  [RhCl(C 19 H 17 P) 2 (CO)] doi:10.1107/S1600536806023798 Acta Cryst. (2006). E62, m1702–m1704 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 trans-Carbonylchlorobis[diphenyl(4-tolyl)- phosphine]rhodium(I) Leo Kirsten, Gideon Steyl* and Andreas Roodt Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa Correspondence e-mail: geds12@yahoo.com Key indicators Single-crystal X-ray study T = 100 K Mean (C–C) = 0.003 A ˚ Disorder in main residue R factor = 0.024 wR factor = 0.062 Data-to-parameter ratio = 18.4 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. Received 5 June 2006 Accepted 21 June 2006 # 2006 International Union of Crystallography All rights reserved The title compound, [RhCl(C 19 H 17 P) 2 (CO)], can be charac- terized as a Vaska-type complex containing a diphenyl(4- tolyl)phosphine ligand. The rhodium(I) metal centre has a square-planar coordination. The molecule is disordered, with the Rh atom lying on an inversion centre. The most important bond lengths and angles include Rh—P = 2.3315 (9) A ˚ , Rh— Cl(trans CO) = 2.405 (2) A ˚ , Rh—C(carbonyl) = 1.724 (11) A ˚ and Rh—C—O = 178.0 (6)  . Comment Rhodium(I) Vaska-type compounds containing chlorine and triphenylphosphine (PPh 3 ) have been extensively investigated in the past few decades (Ceriotti et al., 1983; Chen et al., 1991; Del Pra et al., 1979; Muir & Ibers, 1969; Otto et al. , 1999). Angoletta (1959) reported the original Vaska complex, [IrCl(PPh 3 ) 2 (CO)], in 1959, but it was Vaska & Di Luzio (1961) who later correctly formulated the complex. Functionalization of one of the phenyl rings of PPh 3 with various substituents has also been studied: 4-Me (Suomalainen et al., 2001), 4-Me-benzoate (Dutta et al., 2003), 4-MeO (Suomalainen et al., 2000). In this paper, the crystal structure of the title compound, (I), a 4-TolPh 2 P derivative, is presented. Compound (I) crystallizes with a square-planar geometry about the Rh I metal centre (Fig. 1). Selected bond lengths and angles are given in Table 1. The Rh atom lies on a centre of symmetry, with the Cl atom and carbonyl unit disordered with a ratio of 0.5:0.5. Further disorder in the solid state is observed for the H atoms of the 4-methyl group. The Rh—P, Rh—C and Rh—Cl bond distances are comparable with reported monofunctionalized phenyl– diphenylphosphine complexes (Table 2). The Rh—P bond in (I) is relatively long compared to those in similar structures (CSD, Version 5.27; Allen, 2002), but it correlates well with the tris-4-tolyl derivative (Otto et al. , 1999; Table 2). The short