The solution electronic absorption spectra of low-symmetry mixed ligand complexes—III. Bromochlorotetrakis(pyridine)nickel(II) in chloroform

[Ni(HF2)(3-Clpy)4]BF4 (py = pyridine): Evidence for Spin Exchange Along Strongly Distorted F···H···F– Bridges in a One-Dimensional Polymeric Chain

“…For an r –5 variation of the LF parameters, this translates into a 15–38% increase in these. Both the σ- and π-parameter values for 3-chloropyridine are smaller than those previously reported for pyridine ( e σ py = 4243 cm –1 , e π py = 438 cm –1 ) in trans -NiCl 2 (py) 4 . This is not unexpected because of the inductive effect of the Cl-substituent, but also the much higher donor strength of the bifluoride ligands as compared to Cl – may invalidate the assumption of parameter transferability and contribute to the observed difference.…”