(1H-Benzo[d]imidazol-2-yl)(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl) methanone (L) and its complexes with copper and cobalt chlorides [CuLCl 2] (I) and [CoLCl2] (II) are synthesized and studied by IR spectroscopy. The structure of molecule L is determined by X-ray diffraction analysis. Molecule L crystallizes as a cis-trans isomer. The dihydroisoquinoline (A) and benzimidazole (B) fragments lie in the mutually perpendicular planes. The N-C bond lengths of fragment A (double bond N(1)-C(1) 1.278(3) Å, ordinary bond N(1)-C(9) 1.490(3) Å) differ noticeably. The N-C bond lengths in fragment B range from 1.327(4) to 1.389(4) Å. The C=O bond is 1.218(3) Å According to the data of IR spectroscopy and X-ray diffraction analysis, complexes I and II are assumed to have different structures with different coordination modes to the metal atom of molecule L: through the imine atoms N(1) and N(2) of fragments A and B in I and through the N(1) atom of the dihydroisoquinoline fragment and the O atom of the carbonyl group in II. © 2011 Pleiades Publishing, Ltd.