Phenylmalonate‐Containing Copper( II ) Complexes: Synthesis, Crystal Structure and Magnetic Properties

Three new copper( II ) complexes of formula [Cu(2,2′‐bpy)(Phmal)(H 2 O)]·2H 2 O ( 1 ), [{Cu(2,2′‐bpym)(Phmal)}] n ( 2 ) and [{Cu(phen)(Phmal)}] n ·3 n H 2 O ( 3 ) (Phmal = phenylmalonate; 2,2′‐bpy = 2,2′‐bipyridine; 2,2′‐bpym = 2,2′‐bipyrimidine; phen = 1,10‐phenanthroline) have been prepared and their structures determined by X‐ray diffraction techniques. Complex 1 is mononuclear whereas 2 and 3 are uniform chain compounds. The copper atoms in 1 − 3 are distorted square‐pyramidal: two nitrogen atoms from the bidentate nitrogen heterocycle and two carboxylate oxygen atoms from the phenylmalonate ligand build the equatorial plane; the axial position is filled either by a water molecule ( 1 ) or a carboxylate oxygen atom from another phenylmalonate group ( 2 and 3 ). The values of the intrachain copper−copper separation through the phenylmalonate‐carboxylate bridge in the anti ‐ syn conformation are 4.6853(7) ( 2 ) and 5.014(3) Å ( 3 ). The phenyl ring of the Phmal ligand in 1 produces an unusual intramolecular π−π stacking interaction with the Cu II −(aromatic 2,2′‐bpy) chelate ring. Intrachain edge‐to‐face phenyl−pyridyl and offset phen−phen‐type interactions occur in 2 and 3 , respectively. Magnetic susceptibility measurements of 2 and 3 in the temperature range 1.9−290 K show the occurrence of weak intrachain ferromagnetic interactions between the copper( II ) ions through the phenylmalonate‐carboxylate bridge [ J = +0.10(1) ( 2 ) and +0.31(1) cm −1 ( 3 )]. These values are compared with those reported for malonate‐containing copper( II ) complexes with the same exchange pathway through the anti ‐ syn carboxylate bridge. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)