The first heterometallic copper-cerium polyoxometalate, [{CeIV(OAc)}CuII3(H2O)(B-α-GeW9O34)2]11- (1), is composed of an unprecedented copper(II)-trisubstituted Weakley-type tungstogermanate subunit stabilized by coordination of a {Ce(OAc)}3+ group at the vacant position. The title species contains a central {CeIVCuII3O18} rhomblike cluster that belongs to a new {(4fext)(3dext)(3dint)2} type and magnetically behaves as a triangular Cu3 system with overall antiferromagnetic exchange affected by the structural distortions the vicinity of diamagnetic CeIV induces.
