Structures of hexakis(1-propyltetrazole)iron(II) bis(tetrafluoroborate), [Fe(CHN₄C₃H₇)₆](BF₄)₂, hexakis(1-methyltetrazole)iron(II) bis(tetrafluoroborate), [Fe(CHN₄CH₃)₆](BF₄)₂, and the analogous perchlorates. Their relation to spin crossover behaviour and comparison of Debye–Waller factors from structure determination and Mössbauer spectroscopy

Single-crystal structure determinations of the spin crossover compounds [Fe(ptz) 6 ]X 2 , and [Fe(mtz) 6 ]X 2 (ptz=C 3 H 7 N 4 CH, mtz=CH 3 N 4 CH, X=BF 4 , ClO 4 ) have been performed at different temperatures. The temperature dependence of the lattice constants was measured for the two mtz compounds between 300 and 110 K. The two different structure types for the ptz and mtz compounds are compared and discussed in relation to the physical properties associated with the temperature-induced and light-induced spin transitions. In particular, the atomic displacement parameters for the two inequivalent Fe complexes in the mtz structure were found to be significantly different