STRUCTURE OF BIS(TERT-BUTYL ISOCYANIDE)(MESO-TETRAPHENYLPORPHYRINATO)IRON(II)-BIS(TOLUENE)

The structure of bis(tert-butyl isocyanide)(meso-tetraphenylporphyrinato)iron(II)-bis(toluene) has been determined by three-dimensional, single-crystal X-ray diffraction methods. The material crystallizes with four formula units in space group C2h5-P21/c of the monoclinic system in a cell of dimensions a=22.113 (7) Å, b=12.581 (4) Å, c=19.455 (8) Å, β=94.55 (1)°, and V=5396 Å3 at -150 °C. The structure described by 408 variable parameters has been refined by full-matrix, least-squares techniques to values of the agreement index R (on F2, 8186 data including Fo2<0) of 0.071 corresponding to a value of R (on F, 6747 data having Fo2<3σ7(Fo2)) of 0.049. The geometry about the iron atom is approximately tetragonal with Fe-N(porph) separations of 2.000 (1), 2.010 (2), 2.005 (2), and 2.004 (2) Å and with Fe-CO-BuNC) separations of 1.901 (3) and 1.900 (3) Å. Although there are large deviations of the Fe-C-N-C moiety of the Fe-t-BuNC groups from linearity (Fe-C-N angles, 168.1 (2) and 169.9 (2)°; CNC angles, 159.1 (3) and 165.2 (3)°), we conclude, from crystal packing considerations, that the isocyanide geometry is essentially linear. Such a linear geometry may be expected in the corresponding isocyanide adducts of hemoproteins. © 1979, American Chemical Society. All rights reserved.