680 Acta Cryst. (1993). B49, 680-685 Structure of trans-M(CO)(C4N3)(PPh3)2.1.SC6H6 (M= Ir and Rh): the Pyramidal Geometry of the Tricyanomethanide Anion (C4N3) BY JU-CHUN WANG,* L. J. SHIH, YIH-JrUN CHEN AND YU WANG'{" Department of Chemistry, Soochow University, Taipei, 11102, Taiwan AND FRANK R. FRONCZEK AND STEVEN F. WATKINS Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA (Received 27 May 1992; accepted 9 February 1993) Abstract The crystal structures of two tricyanomethanide (TCM) complexes have been determined. Compound (1), trans-bis(triphenylphosphine)carbonyl(2,2-di- cyanoethylideneamino)iridium(I) (the ligand 2,2-di- cyanoethylideneamino = TCM), was studied at both 298 K (RT) and 135 K (LT). Crystal data: triclinic, a = 11.549(3), b = 12.528 (2), c = 16.931 (2)/~, a= 91.13 (1), /3 = 99.45 (2), y = 114.87 (2) °, final R = 0.039 and wR = 0.054 for the RT structure, and triclinic, a = 11.330 (4), b = 12.337 (4), c = 16.908 (4)]k, a=91.61(2), fl=99.60(3), y= 114.48 (3) °, final R = 0.036 and wR = 0.046 for the LT structure. The RT structure of (2), trans-bis(tri- phenylphosphine)carbonyl(2,2-dicyanoethylidene- amino)rhodium(I), is very similar to the RT structure of (1). Crystal data: triclinic, a = 11.759(3), b = 11.779 (5), e = 16.352 (3),~, a = 102.21 (2), fl = 104.61 (2), y = 94.92 (3) °, final R = 0.070 and wR = 0.079. In both cases the TCM ligand is coordinated to the metal, near linearly through nitrogen, and both metal centers have a distorted square-planar geometry. In the RT structure, the geometry of TCM is planar with one set of unusually large dis- placement parameters for one of the cyano groups. In the LT structure of (1), these large anisotropic displacement parameters were resolved into half- populated C and N sites of disordered cyano groups. The geometry of TCM is thus slightly, pyramidal, with the central C atoms lying 0.115 A out of the plane defined by the three C atoms (C1, C2, C431) bonded to it. Introduction The tricyanomethanide anion (TCM) can coordinate to transition metals through its N end [-N--C--- C(CN)2] with apparent planar geometry. The title * To whom correspondence should be addressed. "{" Department of Chemistry, National Taiwan University, Taipei, Taiwan. © 1993 International Union of Crystallography Printed in Great Britain - all rights reserved Table 1. Experimental details trans-lr(CO)(C4N3)- trans-Rh(CO)(C,N3)- (PPh3)~. 1.5C6H 6 (1) (PPh 3)~. 1.5C6H6 (2) Temperature (K) 298 135 298 Crystal system Triclinic Triclinic Triclinic M, 862.74 952.04 Space group PI PI PI a (A) I 1.549 (3) 11.330 (4) 11.759 (3) b (,~) 12.528 (2) 12.337 (4) 11.779 (5) c (,~,) 16.931 (2) 16.908 (4) 16.352 (3) a () 91.13 (1) 91.61 (2) 102.21 (2) /3 ( ) 99.45 (2) 99.60 (2) 104.61 (2) 2' ( ) 114.87 (2) 114.48 (3) 94.92 (3) V (A ~) 2181.5 (7) 2108.4 (12) 2118.9 (21) z 2 2 2 D, 1.449 1.500 1.352 A (Mo Ka) (A) 0.71073 0.71073 No. of reflections for 25 25 25 lattice parameters 0 range for lattice 10-15.5 11-15 9-12.5 parameters () # (ram ~) 3.16 3.27 0.51 Crystal color Yellow Yellow Yellow Crystal size (mm) 0.25×0.28 × 0.40 x 0.48 × 0.15 x0.15 x 0.50 0.63 0.20 Diffractometer type Enraf-Nonius CAD-4 Data collection method 020 scans Absorption correction type Empirical tO scans Transmission min.--max. 0.746- 1.00 0.641- 1.00 0.821 - 1.00 Standard reflections 3, every 3, every 3, every 72000 s 10000 s 3600 s Variation of standards (%) - 6 - 12.1 - 40 Measured reflections 8061 9248 5850 Independent reflections 7676 9118 5514 Observed reflections 6359 8160 2818 [1 > 3o-(I)] 20 range ( ) 2-50 2-54 2-45 hklrange - 13<h< 12 0<h< 14 - 12<h< 12 0<k<14 -15<k<14 0<k<12 -20<1<20 -21</<21 -17</<17 Refinement based on F F F R, wR 0.039, 0.054 0.036, 0.046 0.070, 0.079 0.039, 0.055* S 1.762 2.190 2.276 1.809* (,a/~r)m,~ 0.04 0.05 0.03 0.05* No. of parameters refined 265 275 279 263* Ap (e ,~ ~) -0.994, 0.986 - 1.665, 1.464 - 1.363, 0.776 - 0.950, 0.968* w 4F,,:/[o'2(1 ) +"(0.02F,,:):] Source of atomic scattering factors International Tablesfor X-ray Crvstallograph.v (1974, Vol. IV) * Values for disordered model of the RT structure of (1). compounds, trans-Ir(CO)(PPh3)2(TCM) (1) and trans-Rh(CO)(PPh3)2(TCM) (2), were the first reported examples of monomeric N-end TCM- transition-metal complexes (Lenarda & Baddley, Acta Crystallographica Section B ISSN 0108-7681 ©1993