Metal halide coordination compounds with quinazolin-4(3H)-one

Three coordination compounds of quinazolin-4(3H)-one (quinoz; C8H6N2O) with divalent group 12 halides are reported. In all complexes, coordination occurs via the nitrogen atom ortho to the quinazolinone carbonyl group. In the two chain polymers with composition [MX2(quinoz)], viz. (M = Cd, X = Br), catena-poly[[[quinazolin-4(3H)-one-kappa N-3]cadmium(II)]-di-mu-bromido], [CdBr2(C8H6N2O)](n) (I), and M = Hg, X = Cl, catena-poly[[[quinazolin-4(3H)-one-kappa N-3]mercury(II)]-di-mu-chlorido], [HgCl2(C8H6N2O)](n) (II), the divalent cations are five-coordinate, with four bridging halide and one terminal quinoz ligand. The Cd-II atom in (I) has an almost trigonal-bipyramidal coordination environment, whereas the Hg-II atom in (II) has a more distorted coordination environment. Likewise, the halide bridges in (II) are significantly more asymmetric than in (I). In both (I) and (II), quinoz ligands at adjacent cations along each strand are oriented in opposite directions, and the organic ligands of neighboring strands interdigitate with resulting pi-pi interactions. In contrast to the halide-bridged chain polymers (I) and (II), the adduct of quinoz with CdI2 is the tetrahedral complex [CdI2(quinoz)(2)], diiodidobis[quinazolin-4(3H)-one-kappa N-3]cadmium(II), [CdI2(C16H12N4O2)], (III). The Cd-II atom in this discrete complex is located on a twofold rotation axis. Disorder in (III) is reflected in an alternative minority orientation of the molecules for which the iodine sites closely match the position of the majority orientation. In view of the low site occupancy of only 0.0318 (8) angstrom, only the Cd-II position for this alternative orientation was taken into account during refinement. In all three compounds, classical N-H center dot center dot center dot O hydrogen bonds with donor-acceptor distances of ca 2.9 angstrom occur; they link the polymer chains in (I) and (II) into di-periodic networks and connect adjacent discrete complexes in (III) to mono-periodic strands.