58031-47-3Relevant academic research and scientific papers
Pressure-induced spin-state phase transitions in Fe(dppen)2Cl2 and Fe(dppen)2Br2
McCusker, James K.,Zvagulis, Maruta,Drickamer, Harry G.,Hendrickson, David N.
, p. 1380 - 1384 (2008/10/08)
The pressure-induced high-spin to low-spin transformation in solid Fe(dppen)2X2, where X = Cl or Br and dppen = cis-1,2-bis(diphenylphosphino)ethylene, has been studied by variable-pressure M?ssbauer spectroscopy. It is found that the dichloro complex undergoes an abrupt first-order phase transition in the region of 7-9 kbar, while the dibromo complex undergoes a more gradual transition starting at approximately 60 kbar. The somewhat more gradual nature of the transformation in the dibromo case likely reflects a first-order phase transition influenced by defect structures. In neither compound is the transition complete: approximately 20% of the molecules remain in the high-spin state for each compound at the highest pressures studied (70 kbar for the dichloro complex and 111 kbar for the dibromo complex). The difference in transition pressures is discussed in terms of lattice cooperativity, in addition to ligand field and polarizability effects manifested with increasing pressure.
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.
