Jahn-Teller distortion in 2-pyridyl-(1,2,3)-triazole-containing copper(ii) compoundsElectronic supplementary information (ESI) available: Experimental IR, UV/vis spectra, MS, additional crystallographic data and optimized coordinates of the DFT calculations. CCDC 1848970-1848974. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8nj03080d

The syntheses, characterization and experimental solid state X-ray structures of five low-spin paramagnetic 2-pyridyl-(1,2,3)-triazole-copper compounds, [Cu(L n ) 2 Cl 2 ], are presented in this study, for the following five L n ligands: L 1 = 2-(1-( p -tolyl)-1 H -(1,2,3-triazol-4-yl)pyridine), L 2 = 2-(1-(4-chlorophenyl)-1 H -(1,2,3-triazol-4-yl)pyridine), L 3 = 4-(4-(pyridin-2-yl)-1 H -(1,2,3-triazol-4-yl)benzonitril), L 4 = 2-(1-phenyl-1 H -(1,2,3-triazol-4-yl)pyridine) and L 5 = 2-(1-(4-(trifluoromethyl)phenyl)-1 H -(1,2,3-triazol-4-yl)pyridine). These five [Cu(L n ) 2 Cl 2 ] complexes each contain two bidentate 2-pyridyl-(1,2,3)-triazole (L n ) and two chloride ions as ligands, with the Cu-N(pyridine) bonds, Cu-N(triazole) and Cu-Cl bonds trans to each other. All five [Cu(L n ) 2 Cl 2 ] compounds display elongation Jahn-Teller distortion, either along opposite Cu-N(triazole) bonds, or along opposite Cu-Cl bonds, as indicated by their obtained solid state crystal structures. Quantum chemistry calculations, using density functional theory, indicated however that elongation Jahn-Teller distortion is in fact possible along any two opposite bonds in these octahedral compounds with the elongation distortion along the opposite Cu-N(triazole) bonds being the most stable structure. Octahedral copper( ii ) compounds, containing two 2-pyridyl-(1,2,3)-triazole ligands as well as two Cl ions, exhibit elongation Jahn-Teller distortion.