78217-10-4Relevant academic research and scientific papers
Singlet ? quintet spin transitions of iron(II) complexes with a P4Cl2 donor set. X-ray structures of the compound FeCl2(Ph2PCH=CHPPh2)2 and of its acetone solvate at 130 and 295 K
Cecconi,Di Vaira,Midollini,Orlandini,Sacconi
, p. 3423 - 3430 (2008/10/08)
While the pseudooctahedral compounds FeX2(dppen)2 with a P4X2 donor set (dppen = cis-1,2-bis(diphenylphosphino)ethylene; X = Cl, Br) maintain μeff values close to 5.0 μB over the range 90-300 K or exhibit smoothly decreasing μeff values with decreasing temperature, the corresponding solvates, with formula FeX2(dppen)2·nS (X = Cl, S = (CH3)2CO, CH2Cl2, CHCl3; X = Br, S = (CH3)2CO) exhibit abrupt temperature-induced spin transitions in the range 190-230 K between the singlet and quintet ground states. An X-ray structural investigation performed on the compound FeCl2(dppen)2·2(CH3)2CO at 295 K (high-spin isomer, space group P21/a, a = 17.867 (4) A?, b = 13.089 (4) A?, c = 11.519 (3) A?, β = 93.30 (3)°, Z = 2) and at 130 K (low-spin isomer, poor quality data, a = 17.02 (2) A?, b = 13.02 (2) A?, c = 11.28 (2) A?, β = 94.3 (1)0) has shown that the Fe-P bond distances decrease dramatically (by ca. 0.28, A? in the mean) in the quintet-to-singlet transition. Comparison with the structure of a polymorph of FeCl2(dppen)2 (295 K, high spin, space group P21/n, a = 16.086 (6) A?, b = 13.189 (6) A?, c - 10.840 (5) A?, β = 90.42 (5)°, Z = 2) indicates that crystal packing and the presence of solvent molecules in the lattice are the factors determining the magnetic properties of these compounds.
