
TY  - JOUR
A1  - Baker, AT 
A1  - Ferguson, NJ 
A1  - Goodwin, HA 
A1  - Rae, AD 
T1  - Structural, Magnetic and Spectral Properties of Iron(II) and Nickel(II) Complexes of N<sup>1</sup>-(Pyridin-2-yl)-3,5-dimethylpyrazole
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1989
VL  - 42
IS  - 5
SP  - 623
EP  - 638
KW  - 
UR  - https://doi.org/10.1071/CH9890623 
N2  - Iron(II) and nickel(II) complexes of N1-(pyridin-2-yl)-3,5-dimethylpyrazole (L) are described. Salts of [FeL3]2+ undergo a reversible temperature-induced singlet (1A1) &#8596; quintet (5T2) transition, both in the solid state and in solution. The singlet- quintet change in acetone solution is characterized by &#916;H = 25 ± 2 kJ mol-1 and &#916;S = 95 ± 5 J K-1 mol-1. Mossbauer spectral data for solid [FeL3] [BF4]2 confirm a change in ground state for the metal atom with change in temperature and indicate two low-spin species at low temperatures and two high-spin species at elevated temperatures. The average M-N bond length changes accompanying the spin change have been estimated as 0.19 Å from data obtained by determination of the structures of [FeL3][ClO4]2 at 135 K and 294 K and of [NiL3][BF4]2 at 294 K by single-crystal X-ray diffractometry. The crystals were all refined as disordered structures in space group P3c1 with Z = 2. Crystal data: [FeL3] [ClO4]2 at 294 K, a = b 10.489(2), 17.521(5) Å ;[FeL3][ClO4]2 at 135 K, a = b 10.355(3), c 17.464(5) Å ; [NiL3] [BF4]2 at 294 K, a = b 10.404(3), c 17.618(8) Å . 
ER  -

