S. J. MAGINN AND R. J. DAVEY 255 V = 1043.3 A 3 Z=4 Dx = 1.39 Mg m -3 Data collection Stoe Stadi-2 diffractometer ~o s c a n s Absorption correction: none 957 measured reflections 772 independent reflections 557 observed reflections [IFI > 4cr(IFI)l gint = 0.026 0max = 50 ° Refinement Refinement on F R -- 0.0465 wR = 0.0465 S = 0.74 557 reflections 94 parameters All H-atom parameters refined 0.45 x 0.25 × 0.20 mm Clear h = -28 ~ 28 k=0~6 l =049 1 standard reflection per layer of k monitored every 25 reflections intensity variation: >2% of I Unit weights applied (A/tr)max = 0.002 Apmax = 0.12 e ~-3 Apmin = -0.13 e ~-3 Atomic scattering factors from International Tables for X-ray Crystallography (1974, Vol. IV) Lists of structure factors, anisotropic displacement parameters, H-atom coordinates and complete geometry have been deposited with the British Library Document Supply Centre as Supplementary Publication No. SUP 71516 (8 pp.). Copies may be obtained through The Technical Ed- itor, International Union of Crystallography, 5 Abbey Square, Chester CH1 2HU, England. [CIF reference: HA1056] References Granger, M. M. & Coiliot, M. F. (1985). Acta Cryst. C41, 542-543. Ito, Y., Matsuura, T., Tabata, K., Meng Ji-Ben, Fukuyama, K., Sasaki, M. & Okada, S. (1987). Tetrahedron, 43, 1307-1312. Johnson, C. K. (1965). ORTEP. Report ORNL-3794. Oak Ridge National Laboratory, Tennessee, USA. Koji6-Prodi6, B., Bresciani-Pahor, N. & Horvati6, D. (1990). Acta Cryst. C46, 430-432. Shields, K. G. & Kennard, C. H. L. (1977). J. Chem. Soc. Perkin Trans. 2, pp. 463-465. Sheldrick, G. M. (1976). SHELX76. Program for Crystal Structure Determination. Univ. of Cambridge, England. Sheldrick, G. M. (1985). SHELXS86. Program for the Solution of Crystal Structures. Univ. of G6ttingen, Germany. Velden, G. P. M. van der & Noordik, J. H. (1979). J. Cryst. Mol. Struct. 10, 83-92. Velden, G. P. M. van der & Noordik, J. H. (1980). J. Cryst. Mol. Struct. 9, 283-294. Table 1. Fractional atomic coordinates and equivalent isotropic displacement parameters (A2) * * a Ueq = ( l /3)EiEjUqa i aj ai. tj. x y z Ueq C(l) 0.05674 (11) 0.1495 (5) 0.2361 (3) 0.053 (2) C(2) 0.06132 ( 1 3 ) 0.3522 (6) 0.3090 (4) 0.060 (2) C(3) 0.11540 ( 1 4 ) 0.4519 (6) 0.3057 (4) 0.070 (2) C(4) 0.16412 ( 1 3 ) 0.3382 (7) 0.2237 (4) 0.077 (2) C(5) 0.16191 ( 1 3 ) 0.1389 (7) 0.1492 (5) 0.074 (2) C(6) 0.10800 (13) 0.0428 (6) 0.1560 (4) 0.062 (2) C(7) 0 0.0309 (7) ] 0.055 (2) F(I) 0.21733 (8) 0.4348 (4) 0.2177 (3) 0.118 (3) 0(1) 0 -0.1663 (6) ] 0.088 (3) Table 2. Selected geometric parameters (]k, C(1)--C(2) 1.374 (4) C(1)--C(6) C(2)--C(3) 1.393 (4) C(1)--C(7) C(3)--C(4) 1.377 (5) C(7)--0(1) C(4)--C(5) 1.353 (5) C(4)--F(1) C(5)--C(6) 1.376 (4) C(7)--C(1)--C(2) 123.2 (3) F(1)--C(4)--C(5) C(7)--C(1)--C(6) 118.2 (3) C(3)--C(4)--C(5) C(2)--C(1)--C(6) 118.5 (3) C(4)--C(5)--C(6) C(1)--C(2)--C(3) 121.8 (3) C(5)--C(6)--C(1) C(2)--C(3)--C(4) 116.7 (3) C(I)--C(7)--O(1) F(1)--C(4)--C(3) 117.3 (4) C(I)--C(7)--C(I') o) 1.396 (4) 1.493 (3) 1.217 (5) 1.364 (3) 118.9 (3) 123.8 (3) 118.4 (3) 120.8 (3) 119.3 (2) 121.4 (2) The data were collected, by two-circle diffractometer, in layers of k and, therefore, inter-layer scale factors were refined (final values of these ranged between 0.73 and 0.94). Structure solu- tion was by SHELXS86 (Sheldrick, 1985) and the refinement used SHELX76 (Sheldrick, 1976). Acknowledgement is made to both Liverpool Univer- sity, for the use of the two-circle diffractometer, and to the SERC, for continued support of the Chemical Data- bank Service at the Daresbury Laboratory. © 1994 International Union of Crystallography Printed in Great Britain - all rights reserved Acta Cryst. (1994). C50, 255-259 Substitution Effects on the Structure of o-Aryliminophosphoranes ANTONIO L. LLAMAS-SAIZ AND CONCEPCION FOCES-FOCES* Departmento de Cristalograffa, Instituto de Quhnica-Ffsica 'Rocaso/ano', CSIC, Serrano 119, E-28006 Madrid, Spain (Received 10 February 1993; accepted 15 June 1993) Abstract The iminophosphorane group in (o-dimethylamino- phenylimino)triphenylphosphorane, C26H2sN2P, lies almost in the benzene plane [C6--C1--N1 l--P12 = -8.3 (3) °] giving rise to an inward distortion of the external angle at C1. The conformation adopted by the dimethylamino group reflects the electronic repulsion between both N-atom lone pairs and places one methyl almost eclipsed by the benzene ring [C3--C2--N31--C33 = - 14.5 (3y']. The optimized geometry (AM1) of o-dimethylaminobenzene shows both groups equally twisted (-27.8") but to a lesser extent than in (o-dimethylaminophenylimino)tri- phenylphosphorane. Acta Crystallographica Section C ISSN 0108-2701 ©1994