Crystal and molecular structure of 1,2,3,4,5,6,7,8-octaethylporphinatodichlorotin(IV) nitromethane solvate

Abstract

2507of the ThzNilv-type structure decreases. This suggests that the degree of order of the ThzNi17-type structures of Pr2C017 and NdzC017 is lowest. Therefore, the ThzNi~v-type compounds for these R elements do not exist. The degree of order of the ThzNi~7-type structures of Ce2C0~7 and Ho2Co17 is nearly ideal. One therefore gets only traces of the ThzZnlv-type structure even after prolonged annealing at lower temperatures. Dy2C017 appears to lie in between these two extreme cases. This is the reason that both modifications i.e.ThzNit7+ThzZnlv-type, are obtained in almost equal proportions below 1200°C.Since those R elements, studied in this work are uniformly distributed throughout the whole rare-earth series, the results obtained for their AzB17 compounds can generally be applied to all the RzCox7 compounds (Fig. 1). Buschow (1966) and Givord, Givord & Lemaire (1972) have explained the polymorphism of RzCo~v in terms of the radii ratios of R and Co atoms. No doubt the atomic radii of R and Co atoms are important factors in the formation of RECO~7. However, the atomic ratio model alone cannot explain the polymorphism of R2Co17 over the rare-earth series and the degree of order of R2Co17 of the Th2Ni17-type structure.In our opinion, the valence-electron concentration and the electron-spatial correlation play a deciding role in the stabilization of one or more of the polymorphic forms of R2C0~7 for a particular R element at a particular temperature.

The structures of (5,10,15,20-tetramethylporphyrinato)nickel(II) and (5,10,15,20-tetramethylchlorinato)nickel(II)

“…(14) A is in the range observed for these porphyrins. The major difference among these structures is the previously observed increase in the Ni-C m distance upon going from the fl-carbon substituted to the meso-substituted porphyrin (Cullen & Meyer, 1973). This increase is accompanied by a decrease in the C,,--Cm--C,, angle.…”

Preparation and characterization of the anionic complex potassium dicyano(meso-tetraphenylporphinato)iron(III) bis(acetone)

“…Similar angle inequivalences (2.5-4.0°) have been observed for the /3-pyrrole alkyl substituents of a number of octaethylporphyrin derivatives. 33 The refined atoms of the phenyl rings of [Fe(TPP)(CN)2]_ were well behaved with (C-H)av = 0.94 (4) A. The average C-C bond distance in the phenyl groups is 1.379 (11) Á.…”

“…The unit cell volume of 2188 Á3 and a cell content of two K[Fe(TPP)(CN)2]-2(CH3)2C=0 led to a calculated density of 1.329 g/cm3; the experimentally determined density was 1. 33 2.7 X I0-6, (c) 6.8 X 10-6, (d) 1.4 X -5, (e) 5.4 X 10-5, (broken line) 3.5 X 10-3 M. High KCN concentration isosbestic points are marked with arrows.…”

Crystal and molecular structure of dimethoxyporphinato-germanium(IV)

“…Although the octahedral nature of germanium in germanium porphyrins has been known for some time on the basis of NMR studies,1-2 recently there has been a surge of general interest in the molecular and electronic structures of group 4 metalloporphyrins. Thus, independent x-ray crystallographic structure determinations have been reported for dichloroa,iS,7,5-tetraphenylporphinatotin(IV), (Cl)2Sn(TPP),3 and dichloro-1,2,...,8-octaethylporphinatotin(IV), (Cl)2Sn(OEP),4 and extended Huckel calculations have been carried out with Si, Ge, Sn, and Pb porphyrin structures.5 '6 In the case of the latter, the influence of the geometry of the molecule on the electronic spectrum of the macrocycle was the point of principal interest.…”