BIS(ARYLDIAZENE) DERIVATIVES OF IRON(II) - PREPARATION, CHARACTERIZATION, AND PROPERTIES OF THE 1ST COMPLEXES CONTAINING 2 DIAZENE LIGANDS BONDED TO THE SAME CENTRAL METAL - THE X-RAY CRYSTAL-STRUCTURES OF HEXACOORDINATE [FEH(4-CH3C6H4NNH)(P(OET)3)4]+ AND PENTACOORDINATE [FE(4-CH3C6H4N2)(P(OET)3)4]+ CATIONSS

The complexes [FeH(ArN=NH)L4]BPh4(1) and [Fe(ArN=NH)2L4](BPh4)2(2) [L = P(OEt)3; Ar = 4-CH3C6H4 (a), 4-CH3OC6H4(b), 4-FC6H4(C)] were prepared by reacting hydride FeH2L4 with aryldiazonium cations in CH2C12 at –80 °C. Their characterization by 1H and 31P{1H} NMR (with 15N isotopic substitution) is reported. The reaction of bis(diazene) 2 with triethylamine was investigated and led to the synthesis of new pentacoordinate [Fe(ArN2)L4]+(3) [Ar = 4-CH3C6H4 (a), 4-CH3OC6H4(b), 4-FC6H4 (c)] aryldiazenido complexes, which were isolated and characterized by infrared and 31P{1H} NMR spectroscopy. The structures of compounds la and 3a were determined crystallographically. The compounds crystallize in the space group P21/n (a = 21.271 (8) Å, b = 15.727 (4) Å, c = 20.580 (7) Å, β = 1 12.77 (3)°, and Z = 4) and P1 (a = 14.834 (8) Å, b = 18.942 (10) Å, c = 11.738 (6) Å, a = 100.59 (4)°, β = 90.36 (5)°, 7 = 95.52 (4)°, and Z = 2), respectively. Both structures were solved by heavy-atom techniques and were refined by least-squares calculations to R = 0.0839 and 0.0779, respectively. In la the iron cation is six-coordinate with the diazene and the hydride ligand in mutually cis position. The structure of 3a consists of discrete cations and anions. The cation is five-coordinate with coordination geometry close to trigonal bipyramidal with an equatorial single-bent aryldiazenido group. Significant angles and distances are the following: Fe–N(l) =1.672 (9) Å, N(1)–N(2) = 1.224 (13) A; Fe-N(1)–N(2) = 166.6 (9)°, N(1)-N(2)–C(p-tolyl) = 120.3 (10)°. © 1986, American Chemical Society. All rights reserved