Crystal and molecular structure of dimethoxyporphinato-germanium(IV)

Abstract

The crystal and molecular structure of dimethoxyporphinatogermanium(IV), (MeOkGeCP), has been determined by x-ray crystallographic methods. The compound crystallizes in the monoclinic system, a = 15.013 (5), b = 14.441 (5), c = 8.414 (4) Á., ß = 91.85 (2)°, space group P2\/c with four molecules per unit cell. The structure was solved through the application of Sayre's equation. The crystal structure is unusual in that the asymmetric unit consists of two crystallographically independent half-molecules located at centers of symmetry. The germanium coordination corresponds to that of a slightly distorted octahedron with the methoxy groups in apical positions. The averaged structures of the independent molecules are the same except for the orientation of the methoxy groups and the structures closely approximate Duh symmetry. The independent pyrrole rings have a geometry similar to that of the azapyrrole of free base porphine and there is a general "squaring-up" and overall contraction of the central core region of (MeOhGeCP) compared to the free base. The density of (MeO)2Ge(P) is the largest of all porphyrins, especially when normalized with respect to the central ion. The abnormally large density is probably due to the fact that the molecular centers are located at face centered positions so that the packing is based upon a close packed arrangement.

The crystal and molecular structure of chloro-.alpha.,.beta.,.gamma.,.delta.-tetraphenylporphinatomanganese(III)

“…In the majority of cases, if the purine (A) is substituted in the N(9) position, the metal will coordinate to N(7); the only known exception to this rule occurs2 in the trichloro(9-methyladenine)zincate(II) ion, [ZnCl3(9MA)]~, where the metal coordinates to N(l). In unsubstituted purines, the metal will coordinate to the imidazole nitrogen which is protonated in the free neutral ligand (N(7) for theophylline and N(9) for all other naturally occurring purines1); the only known exception to this rule is3 trichloro(adeninium)zinc(II), [ZnCl3(AH)j, where the metal coordinates to N (7). The N(9) position in this compound is…”

Isomers in the Chemistry of Germanium Coordination Compounds

“…The -and -Ge( 4 -tpp)(MeO) 2 [3,4] isomers are different not only by degree of distortion, but also by crystal class, -being monoclinic and -tetragonal. In additional -contains two crystallographically independent molecules.…”

“…Purple Ge( 4 -tpp)(MeO) 2 is only example, which exists in two isomeric forms, monoclinic [3] and tetragonal [4] and in addition, the monoclinic contains two crystallographicaly independent molecules. A six coordinate environment around each Ge(IV) is created by one tetradentate tpp ligand (4 N) and two unidentate MeO ligands (GeN 4 O 2 ).…”

“…Each Ge(II) atom is three coordinated. -anions have trigonal pyramidal structure with Cl -Ge -Cl angles in [5] with the mean values of 96.07 (3,78) o (molecule 1) and 96.04 (3, 2.63) o molecule 2; and in [6] 95. 6 (5.3) o (molecule 1) and 96.5 (4,5) o (molecule 2).…”

Germanium Coordination Compounds: Classification and Analysis of Crystallographic and Structural Data

“…The data for over thirty derivatives with coordination number six are given in [83,84,107,108], Also found are situations involving a bidentate plus four unidentate ligands [94], two bidentate and two unidentate ligands [85][86][87]99,109,110], three bidentate ligands [88,89,91], two terdentate ligands [100], one tetradentate and two unidentate ligands [92,[101][102][103][104][105][106], one penta-and one unidentate ligand [94][95][96][97][98] and by one hexadentate ligand [90], In six of the derivatives [85,103.106,108] six donor atoms create a near ideal Oh symmetry about Ge(IV). All the remaining examples exhibit a distorted geometry with a compressed tetragonal bipyramidal geometry.…”