Spin crossover in chromium(II) complexes and the crystal and molecular structure of the high spin form of bis[1,2-bis(diethylphosphino)ethane]di-iodochromium(II)

From the variation of magnetic properties with temperature trans-bis[1,2-bis(diethylphosphino)ethane]-di-iodochromium(II) undergoes a sharp S= 2 to S= 1 spin-state transition between 165 and 175 K.