Received 30 September 2010
In the title compound [systematic name: 3,3'-Dibutyl-1,1'-(5-methyl-m-phenylenedimethylene)diimidazol-1-ium bis(hexafluoridophosphate)], C23H34N42+·2PF6-, the imidazole rings are inclined at angles of 68.06 (7) and 75.05 (8)° with respect to the central benzene ring. In the crystal, molecules are linked into one-dimensional columns along  via weak intermolecular C-HF hydrogen bonds. The crystal structure is further consolidated by weak C-H(arene) interactions. One of the n-butyl groups is disordered over two sites with refined occupancies of 0.694 (5) and 0.306 (5). In addition, four of the F atoms of one of the PF6- cations are disordered over two sites with occupancies of 0.64 (3) and 0.36 (3).
For general background to imidazoline-2-ylidenes, see: Arduengo et al. (1991). For the organometallic and coordination chemistry of N-heterocyclic carbene ligands, see: Chen et al. (2002); Zhou et al. (2008); Hahn & Jahnke (2008); Danopoulos et al. (2007); Bourissou et al. (2000); McGuinness & Cavell (2000); Garrison et al. (2001). For catalytic studies related to organic synthesis, see: Cavell & McGuinness (2004); Liu et al. (2007). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986). For standard bond-length data, see: Allen et al. (1987).
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5143 ).
RAH, AW and SGT thank Universiti Sains Malaysia (USM) for the FRGS fund (203/PKIMIA/671115), the short term grant (304/PKIMIA/639001) and the Research University Grant (1001/PKIMIA/813023). HKF and CKQ thank USM for the Research University Grant (1001/PFIZIK/811160) and CKQ also thanks USM for a research fellowship.
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