{4-[(7-Chloro-4-quinolyl)amino]-N,N-diethylpentanaminium}(triphenylphosphine)gold(I) dinitrate

The title compound, [Au(C18H27ClN3)(C18H15P)](NO3)2, is a coordination complex of gold(I) triphenylphosphine with the N atom in the quinoline ring of the common antimalarial compound chloroquine (CQ). The pendant diethylamino group of the CQ ligand was found to be protonated. The complex exhibits a nearly linear coordination geometry around the AuI atom [N—Au—P = 176.94 (6)°], with Au—N and Au—P bond lengths of 2.070 (2) and 2.2338 (7) Å, respectively. The diethylammonium group and one of the two nitrate counter-ions are disordered with occupancy ratios of 0.519 (4):0.481 (4). The nitrate anions are hydrogen bound to both the amino and ammonium groups of the N,N-diethylpentanaminium fragment of the CQ.

The title compound, [Au(C 18 H 27 ClN 3 )(C 18 H 15 P)](NO 3 ) 2 , is a coordination complex of gold(I) triphenylphosphine with the N atom in the quinoline ring of the common antimalarial compound chloroquine (CQ). The pendant diethylamino group of the CQ ligand was found to be protonated. The complex exhibits a nearly linear coordination geometry around the Au I atom [N-  ], with Au-N and Au-P bond lengths of 2.070 (2) and 2.2338 (7) Å , respectively. The diethylammonium group and one of the two nitrate counter-ions are disordered with occupancy ratios of 0.519 (4):0.481 (4). The nitrate anions are hydrogen bound to both the amino and ammonium groups of the N,Ndiethylpentanaminium fragment of the CQ.  (1996); Navarro et al. (1997,2004). Widespread use of CQ has led to cross-resistance, limiting the efficacy of CQ-related treatments for malaria, see: World Health Organization (2010).

Experimental
Crystal data [Au(C 18 H 27 Table 1 Hydrogen-bond geometry (Å , ). In the title complex ( Fig. 1) gold(I) is coordinated to the nitrogen atom in the quinoline ring as proposed earlier (Navarro et al. 1997). The complex exhibits a nearly linear coordination geometry around gold, with an N-Au-P angle of 176.94 (6)°.
The Au-N and Au-P bond distance are 2.070 (2) Å and 2.2338 (7) Å, respectively. These bond distances are similar to those found in thre structure of (triphenylphosphine)gold(I) chloride, with Au-P 2.2313 (4) Å (Borissova et al., 2008), as well as the Au-N and Au-P distances in the structure of the cationic pyridine adduct (triphenylphosphine)gold(I) pyridine tetrafluoroborate, with Au-N 2.073 (3) Å and Au-P 2.2364 (8) Å (Thwaite et al., 2004). The pendant diethylamino group (N4) of the CQ ligand in the title complex was found to be protonated, and the nitrate anions are hydrogen bound to both the N1 amino and N4 ammonium groups of the 1,4-pentanediamine fragment of the CQ.

Refinement
Hydrogen atoms on carbon were included in calculated positions and were refined using a riding model at C-H = 0.95, 0.98 and 0.99 Å and U iso (H) = 1.2, 1.5 and 1.2 × U eq (C) of the aryl, methyl and methylene C-atoms, respectively. The hydrogen atom on N4 was refined semi-freely with the help of a distance restraint at N-H = 0.88 Å and U iso (H) = 1.2 × U eq (N).
The presence of a residual electron density peak and the proximity of a nitrate anion indicated that N5 was protonated.
Hydrogen atoms on N5 were included in calculated positions and were refined using a riding model at N-H = 0.93 Å and U iso (H) = 1.2 × U eq (N) .
supplementary materials sup-2 Figures Fig. 1. A view of the title complex, with displacement ellipsoids shown at the 50% probability level. H atoms on carbon have been omitted for clarity; primed atoms represent the disordered fraction of the NO 3 ion and the diethylammonium group.