metal-organic papers m2616 Klitgaard and Magnussen  [CrCl 3 (C 9 H 21 N 3 )] doi:10.1107/S1600536805037086 Acta Cryst. (2005). E61, m2616–m2617 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 Trichloro(1,4,7-trimethyl-1,4,7-triazacyclo- nonane)chromium(III) Søren Kegnaes Klitgaard* and Magnus Magnussen Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark Correspondence e-mail: sork@kiku.dk Key indicators Single-crystal X-ray study T = 122 K Mean (C–C) = 0.001 A ˚ R factor = 0.027 wR factor = 0.060 Data-to-parameter ratio = 78.1 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2005 International Union of Crystallography Printed in Great Britain – all rights reserved The structure of the title complex, [CrCl 3 (C 9 H 21 N 3 )], contains a distorted octahedral chromium(III) centre. The facial tridentate N-coordinating 1,4,7-trimethyl-1,4,7-triazacyclo- nonane ligand and three chloride ions make up the first coordination sphere. Comment The 1,4,7-trimethyl-1,4,7-triazacyclononane (tmtacn) ligand has become one of the classic ligands in coordination chem- istry (Wieghardt et al., 1982). In recent years, tmtacn–metal complexes have attracted attention in the area of ‘single- molecule magnets’, where tmtacn acts as a capping ligand in metal–cyanide cluster compounds, as described by Shores et al. (2004, and references therein). We report here the crystal structure of the title complex, [Cr(tmtacn)Cl 3 ], (I). Complex (I) was prepared as a precursor for the above- mentioned metal–cyanide cluster compounds and is isostruc- tural with the scandium(III) (Hajela et al., 1997), titanium(III) (Bodner et al., 1992), iron(III) (Silver & Trogler, 1995) and ruthenium(III) (Schneider et al., 1994) analogues. The bond lengths (Table 1) are similar to those of the tri-n- butyl-substituted analogous complex Cr(Bu 3 tacn)Cl 3 , (Wu & Stahly, 1995) [Cr—N = 2.142 (2)–2.154 (2) A ˚ ; Cr—Cl = 2.3196 (9)–2.3308 (9) A ˚ ]. The Cr—Cl and Cr—N bond lengths are shorter than those of the scandium [Sc—Cl = 2.406 (2) A ˚ ; Sc—N = 2.337 (2) A ˚ ] and titanium [Ti—Cl = 2.352 (1) A ˚ ; Ti— N = 2.256 (3) A ˚ ] analogues, which is in agreement with the decrease of the relative ionic radii. Experimental Complex (I) was prepared by adding one equivalent of the tmtacn ligand to an acetonitrile solution of [Cr(THF) 3 Cl 3 ]. Crystals suitable for X-ray diffraction were obtained by slow evaporation of the filtered acetonitrile solution. Received 30 September 2005 Accepted 10 November 2005 Online 16 November 2005