Low-frequency i.r. spectral assignments for transition metal poly(1-pyrazoyl)borate complexes

Abstract The low-frequency i.r. spectra (650-150 cm −1 ) of M [HB(pz) 3 ] 2 , M [B(pz) 4 ] 2 and M [HB(3,4,5-(CH 3 ) 3 pz) 3 ] 2 , where M is Fe, Co, Ni, Cu and Zn, have been measured and assigned. The M -N stretching bands are assigned based on the metal—isotope substitution method and are correlated with their CFSE. The low-frequency i.r. spectra of the spin-equilibrium complex Fe[HB(3,5-(CH 3 ) 2 pz) 3 ] 2 has been interpreted for room and liquid nitrogen temperatures.