Synthesis, molecular structural studies and DFT calculations of tricarbonylrhenium(I) metal complexes containing nitrogen based N∩N donor polypyridyl ligands

•Metal complexes are having supramolecular non-covalent interactions.•DFT calculations were shown that bond energy gap is more due to the hydrogen bonding interaction.•Some of the complexes are having luminescence properties.

The reaction of [Re(CO)5Br] with the corresponding N,N′-donor polypyridyl ligands (L1–L8) leads to the formation of mononuclear tricarbonylrhenium(I) complexes having the general formula fac-[Re(L)(CO)3Br] (1–8), where L = dpt-NH2 (L1), Hbpp (L2), pypypm (L3), dppn (L4), dpp (L5), dpp3Me (L6), dppMe (L7) and bpzpy (L8). All these nitrogen donor planar ligands react with the metal precursor under nitrogen atmosphere to form tricarbonylrhenium(I) complexes [Re(N∩N)(CO)3Br] (1–8). All these metal complexes were isolated as neutral complexes and were characterized by FT-IR, 1H NMR, UV–Vis and Mass spectroscopic techniques. Complexes (1–6 & 8) were structurally determined by single-crystal X-ray diffraction technique. Single crystal X-ray crystallographic data conforms that the molecular structure of [Re(N∩N)(CO)3Br] is distorted octahedron around the rhenium atom with one Br-atom, facial arrangement of three CO groups and one polypyridyl ligand. The molecular orbital diagrams of the complexes (1–6 & 8) have been obtained from the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions for the metal complexes [Re(N∩N)(CO)3Br] have been calculated with the time-dependent DFT (TDDFT) method which are in good agreement with the experimental values.

Graphical abstractA new series of mononuclear rhenium(I) polypyridyl complexes have been synthesized by the reaction of metal precursor with bidentate polypyridyl ligands in toluene medium and these metal complexes has been characterized by the spectral studies. These mononuclear rhenium(I) polypyridyl complexes has the supramolecular structure with non-covalent interactions (hydrogen bonding, C–H⋯π and π–π [∼3.421 Å] stacking).Figure optionsDownload full-size imageDownload as PowerPoint slide