A new oxo centered basic p-chlorobenzoate bridging heterotrinuclear complex, [Cr2MnO(C7H4O2Cl)6(Py)3]C7H5O2Cl: Synthesis, X-ray crystal structure and theoretical DFT study

The direct reaction between p-chlorobenzoic acid and metal nitrate salts resulted in the formation of a novel heterometallic μ3-oxo trinuclear cluster with the formula [CrIII2MnIIO(C7H4O2Cl)6(Py)3]C7H5O2Cl (1), which has been characterized by elemental analysis, electronic and IR spectra, and single-crystal X-ray crystallography. The electronic spectrum of the complex exhibited two spin-allowed bands for CrIII in the regions 17 900 and 22 750 cm−1, which could be assigned to the transitions from 4A2g(F) to 4T2g(F) and 4T1g(F), respectively. We have also examined the Cambridge Structural Database to investigate the abundance of this type of complex in terms of the trivalent/divalent metal ions and the hetero/homometallic nature of the trinuclear cluster. We have studied the relative stability of the different cluster situations, calculating the energetic costs of a series of metal substitution reactions by means of high level DFT calculations. Moreover, we have analyzed the effect of the p-chlorine substituent in benzoic acid, since the formation of halogen bonding interactions in the solid state are important in determining the crystal packing of 1.

Graphical abstractHere, we report the synthesis and X-ray characterization of a new CrIII2MnII cluster using p-chlorobenzoic acid as a bridging carboxylate ligand, namely [CrIII2MnIIO(C7H4O2Cl)6(Py)3]C7H5O2Cl (1). We have focused our attention on the crucial role of halogen bonding interactions in determining the solid state architecture of 1. In addition, we have studied the influence of the carboxylate coordination on the ability of the chlorine to form halogen bonding interactions by means of DFT calculations in a model system.Figure optionsDownload full-size imageDownload as PowerPoint slide