Electrical Conducting and Magnetic Properties of (Ethylenedithiotetrathiafulvalenothioquinone-1,3-diselenolemethide)2·FeBr4 (GaBr4) Crystals with Two Different Interlayer Arrangements of Donor Molecules

The effect of a sixth ligand in a series of low-spin thiocarbonyl-ligated iron(II)octaethylporphyrinates has been investigated. Sixcoordinate complexes have been synthesized and characterized by M?ssbauer and infrared spectroscopy and single-crystal X-ray structure determinations. The results are compared with the five-coordinate parent complex. The crystal structures of [Fe(OEP)(CS)(1MeIm)] and [Fe(OEP)(CS)(Py)] are reported and discussed. The 1-methylimidazole and pyridine derivatives exhibit Fe-C(CS) bond distances of 1.703(4) and 1.706(2) (angstrom) that are significantly longer than the 1.662(3) (angstrom) reported for five-coordinate [Fe (OEP)(CS)] (Scheidt, W. R.; Geiger, D. K. Inorg. Chem. 1982, 21, 1208). The trans Fe-N(ligand) distances of 2.112(3) and 2.1550(15) (angstrom) observed for the 1-methylimidazole and pyridine complex are ~0.13 (angstrom) longer than those observed for analogous bis -ligated complexes and are consistent with a significant structural trans effect for the CS ligand. M?ssbauer investigations carried out for five- and six-coordinate thiocarbonyl derivatives with several different sixth axial ligands reveal interesting features. All derivatives exhibit very small isomer shift values, consistent with a very strong interaction between iron and CS. The five-coordinate derivative has Fe = 0.08 mm/s, and the six-coordinate complexes exhibit Fe = 0.14 to 0.19 mm/s at 4.2 K. The five-coordinate complex shows a large quadrupole splitting ((delta)Eq = 1.93 mm/s at 4.2 K) which is reduced on coordination of the sixth ligand ((delta)Eq = 0.42-0.80 mm/s at 4.2 K). Addition of a sixth ligand also leads to a small decrease in the value of CS. Correlations in structural, IR, and Mossbauer results suggest that the sixth ligand effect is primarily induced by changes in(sigma)-bonding. The structure of [Fe(OEP)(CS)(CH3OH)] is briefly reported. Crystal data: [Fe(OEP)(CS)(1-MeIm)] crystallizes in the monoclinic system, space group P21/n, Z = 4, a = 9.5906(5) (angstrom), b = 16.704(4) (angstrom), c = 23.1417(6) (angstrom), = 100.453(7). [Fe(OEP)(CS)(Py)] crystallizes in the triclinic system, space group P, Z = 5, a = 13.9073(6) (angstrom), b = 16.2624(7) (angstrom), c = 22.0709(9) (angstrom),(alpha)= 70.586(1),(beta)= 77.242(1),(gamma)= 77.959(1). [Fe(OEP)(CS)(CH3OH)] crystallizes in the triclinic system, space group P, Z = 1, a = 9.0599(5) (angstrom), b = 9.4389(5) (angstrom), c = 11.0676(6) (angstrom),(alpha)= 90.261(1),(brta)= 100.362(1),(gamma) = 114.664(1).