The complex [CuL(NO3)2] · CH3CN(I), where L is 1-(3-methyl-1-phenylpyrazol-5-onylidene-4)-3,3-dimethyl-1,2,3,4- tetrahydroisoquinoline, is synthesized and studied by X-ray diffraction and IR and electronic absorption spectroscopies. Complex I is prepared by the reaction of copper(II) nitrate crystal hydrate with L in acetonitrile. The coordination polyhedron of the Cu atom in I is a distorted (4 + 1) five-vertex polyhedron, and ligand L in the structure acts as N,O-bidentate bridge. The nitrate groups in I perform different structural functions: monodentate-terminal and anisobidentate. Structure I is composed of polymeric chains -L-Cu(NO 3)2-L- and solvate acetonitrile molecules arranged between the chains. © 2005 Pleiades Publishing, Inc.