PHOSPHANIMINE AND PHOSPHORANEIMINATO COMPLEXES OF IRON - THE CRYSTAL-STRUCTURES OF [FECL3(ME(3)SINPET(3))], [FECL2(ME(3)SINPET(3))](2), [FECL2(NPET(3))](2), AND [FE(O2C-CH3)(2)(NPET(3))](2)

The phosphanimine complexes [FeCl3(Me(3)SiNPEt(3))] (red-orange) and [FeCl2(Me(3)SiNPEt(3))](2) (colourless) have been prepared by reactions of Me(3)SiNPEt(3) with FeCl3 and FeCl2, respectively, in CH2Cl2 suspensions. Thermal decomposition of these donor-acceptor complexes in boiling toluene leads to the phosphoraneimirato complex [FeCl2(NPEt(3))](2) (black), whereas [Fe(O2C-CH3)(2)(NPEt(3))](2) (brown) is formed from iron(II) acetate and Me(3)SiNPEt(3) in boiling acetonitrile. The complexes are characterized by IR spectroscopy and by crystal structure determinations. [FeCl3(Me(3)SiNPEt(3)) (1): Space group P2(1)/c, Z = 8, structure determination with 4673 unique reflections, R = 0.033. Lattice dimensions at -15 degrees C: a = 1607.8, b = 1602.0, c = 1417.2pm, beta = 106.56 degrees. 1 forms monomeric molecules with tetrahedrally coordinated iron atoms. Bond lengths in average: Fe-N = 196.9 pm, Fe-Cl = 219.7 pm. [FeCl2(Me(3)SiNPEt(3))](2) (2): Space group P2(1)/c, Z = 4, structure determination with 4992 unique reflections, R = 0.048. Lattice dimensions at 20 degrees C: a = 1457.9, b = 1685.4, c = 1507.3 pm, beta = 116.74 degrees. 2 forms dimeric molecules, which are associated by chloro bridges. The iron atoms are tetrahedrally coordinated with trans positions of the phosphanimine ligands. Both lengths in average: Fe-N = 202.2 pm, Fe-Cl-terminal = 224.7 pm, Fe-Cl-bridge = 241.0 pm. [FeCl2(NPEt(3))](2) (3): space group P2(1)/n, Z = 2, structure determination with 2763 unique reflections, R = 0.039. Lattice dimensions at - 70 degrees C: a = 799.1, b = 1009.0, c = 1441.9 pm, beta = 93.45 degrees. 3 forms centrosymmetric dimeric molecules, in which the tetrahedrally coordinated iron atoms are associated by the nitrogen atoms of the phosphoraneiminato ligands. Bond lengths in average: Fe-N = 191.4 pm, Fe = Cl = 222.7 pm. [Fe(O2C-CH3)(2)(NPEt(3))](2) (4): Space group P2(1)/n, Z = 2 structure determination with 3005 observed unique reflections, R = 0.034. Lattice dimensions at -65 degrees C: a = 886.4, b = 1112.7, c = 1444.6 pm, beta = 90.60 degrees. 4 forms centrosymmetric dimeric molecules, in which the octahedrally coordinated iron atoms are associated by the nitrogen atoms of the phosphoraneiminato ligands with bond lengths Fe-N of 191.9 and 195.0 pm. The acetate groups are coordinated in a chelating fashion.