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Crystal Structure of the Orthorhombic Modification of a Mononuclear Peroxotitanium(IV) Dipicolinate
Author(s) -
Manohar H.,
Schwarzenbach D.
Publication year - 1974
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19740570416
Subject(s) - triclinic crystal system , chemistry , orthorhombic crystal system , crystallography , pentagonal bipyramidal molecular geometry , diffractometer , bond length , crystal structure , ligand (biochemistry) , bipyramid , chelation , norbornane , bent molecular geometry , stereochemistry , inorganic chemistry , biochemistry , receptor , organic chemistry
The deep red diaquoperoxotitanium dipicolinate [TiO 2 (C 7 H 3 O 4 N) (H 2 O) 2 ]2H 2 O crystallises in a pleochroic triclinic and a nonpleochroic orthorhombic modification. The structure of the former has been reported earlier. The structure of the latter, described in this paper, has been determined from X‐ray diffractometer data and refined to R = 0.034. In both forms the complex occurs as the free acid, but the modes of packing are completely different. Bond lengths and angles agree closely. As in the other peroxotitanium(IV) chelate structures so far determined, titanium has an approximately pentagonal bipyramidal coordination with the peroxo group and the chelate ligand occupying equatorial sites and the waters forming the apices. The relationship proposed earlier between the basicity of the ligands and the bond lengths and colours of the related compounds is substantiated. The final difference Fourier maps obtained with normal and modified refinement procedures clearly reveal bonding electron densities. They indicate a pentagonal bipyramidal sp 3 d 3 hybridisation of titanium with bent Ti‐O peroxo bonds, again in agreement with the triclinic form and other peroxotitanium chelates.