Heterobimetallic lanthanide-gold coordination polymers: structure and emissive properties of isomorphous [nBu4N]2[Ln(NO3)4Au(CN)2] 1-D chains

A new series of lanthanide-containing dicyanoaurate coordination polymers, [(Bu4N)-Bu-n](2)[Ln(NO3)(4)Au(CN)(2)] (Ln = Nd, Eu, Gd or Tb), were synthesized and structurally characterized. They form an isomorphous series, crystallizing in the space group I2(1)2(1)2(1). The structure is composed of a one dimensional zigzag of Ln-N-C-Au-C-N-Ln chains with no intra-or inter-chain aurophilic interactions. The series is related to and can be described as a reduced dimensionality analogue of the previously studied Ln[Au(CN)(2)](3)center dot 3H(2)O. Unlike the Ln[Au(CN)(2)](3)center dot 3H(2)O series, there is no efficient energy transfer between dicyanoaurate and the lanthanide metal centers in the complexes and they essentially act as two separate emissive chromophores.