A dinuclear manganese(II) complex {[Na2(H2O)4Mn2(μ-pmtz)4(NCS)2]·xH2O}n with 5-(pyrimidyl)tetrazolato bridges involved in 1D ladder-like chains: Synthesis, X-ray structure, magnetic properties and DFT calculations

A dinuclear manganese(II) unit of the composition {[Na2(H2O)4Mn2(μ-pmtz)4(NCS)2]·xH2O}n (1·xH2O) (x = 3 or 0.5), where pmtz = 5-(pyrimidyl)tetrazolate(1−), involved in 1D ladder-like chains mediated through pmtz bridges, was prepared and characterized by elemental analysis, FT-IR spectroscopy, simultaneous thermogravimetric (TG) and differential thermal (DTA) analyses, single crystal X-ray analysis and magnetic measurements, accompanied by DFT calculations. The magnetic data, treated with the spin Hamiltonian formalism, revealed a weak antiferromagnetic exchange mediated via the κ2N1,N7:κN2 chelating/bridging mode of pmtz. This finding was also supported by the DFT calculations performed on the experimentally determined geometry of the dinuclear manganese(II) unit at the B3LYP/TZVP and B2PLYP/TZVP levels of theory.

Graphical abstractAn unusual 1D ladder-like manganese(II) complex, {[Na2(H2O)4Mn2(μ-pmtz)4(NCS)2] ·xH2O}n (1·xH2O) (x = 3 or 0.5), involving two types of 5-(pyrimidyl)tetrazolato (pmtz) bridges has been prepared. The magnetic analysis revealed a very weak antiferromagnetic exchange mediated by the κ2N1,N7:κN2 chelating/bridging mode of pmtz. The non-isotropic axial zero-field splitting term, D, was essential for a proper description of the overall magnetic behaviour. A weak antiferromagnetic exchange was also supported by the DFT calculations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► An unusual 1D ladder-like chain assembled from 5-(pyrimidyl)tetrazolato bridged dinuclear manganese(II) units. ► An antiferromagnetic exchange mediated through the tetrazole rings was found. ► DFT calculations at the B3LYP and B2PLYP/TZVP levels support a weak isotropic exchange.