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Title: Some complexes of chromium with nitrogen and oxygen donor ligands
Author: Roberts, Andrew John
ISNI:       0000 0001 3520 8897
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1981
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A number of chromium(II) compounds have been prepared under anaerobic conditions and investigated by spectroscopic, magnetic and other techniques, also carried out in the absence of air. The new compounds of chromium(II) include those with substituted pyridines and thiocyanate, Cr(L)[2](NCS)[2] (L=3,5-dimethylpyridine, 3-bromopyridine, 3-iodopyridine, 3,5-dichloropyridine or iso-quinoline). These complexes all show antiferromagnetic behaviour and have been shown to possess a polymeric structure with bridging thiocyanate. Some complexes of 2,2'-dipyridylamine with chromium(II) have also been prepared including Cr(L)X[2] (L=2,2'-dipyridylamine; X=NCS, NCO or 1/2SO[4]) and Cr(L)[2]X[2] (L=2,2'-dipyridylamine; X=Cl, Br or I). The halide complexes have a distorted octahedral structure and show normal magnetic behaviour, whilst the others have polymeric structures and show antiferromagnetic behaviour, except for the sulphate which shows normal behaviour. These complexes include the first cyanato-chromium(II) complex which also provides the first example of bridging cyanate. Two new compounds of chromium(II) with the macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane ([14]aneN[4]) have been prepared i.e. Cr([14]aneN[4])XPF[6]. H[2]O, where X=Cl or Br; these have been shown to have a polymeric structure with bridging halide and also show antiferromagnetic behaviour. Chromium complexes of polymeric Schiff bases derived from 5,5'-methylenebis(salicylaldehyde) and either 4,4'-methylenebis(cyclohexylamine) or 3,3'-diamino-N-methyldipropylamine have been prepared and shown to contain chromium(III) contrary to earlier reports where they were said to contain chromium(II). A new series of chromium(II) complexes has been prepared where the axial aquo ligands of diaquotetra-u-carboxylatodichromium(II) complexes are replaced by thiocyanate. The complexes [Et[4]N][2][Cr[2(]RCOO)[4](NCS)[2]] (R=CH[3],CH[3]CH[2]) are diamagnetic and show evidence of a metal-metal bond as does the complex Cr(CH[3](CH[2])[16]COO)[2].H[2]O, which was also prepared.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Chemistry, general