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Title: Studies on transition metal polythia macrocyclic complexes
Author: Halcrow, Malcolm A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1991
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An introduction to macrocyclic coordination chemistry is presented and the general aims of the project are discussed. The syntheses and structural characterisation of the dimeric bi-octahedral complexes [Ni2(S4)2(μ-Cl)_2]^2+ (S_4 = [12]aneS_4, [14]aneS_4, of [Ni(H_2O)_6)]^2+ by [12]aneS_4 and [16]aneS_4 is discussed: [Ni[16]aneS_4)-(OH_2)_2]^2+ exhibits a trans-octahedral stereochemistry by x-ray crystallography. The syntheses and characterisation of the five-coordinate complexes [Ni([9]aneS_3)(PP)]^2+ (PP = diphosphine chelate) are presented. Four complexes in the series have been shown to adopt square-pyramidal geometries by single crystal x-ray analysis. The synthesis and single crystal structure of the square-pyramidal species [Ni([15]aneS_5)]^2+ is also described. [Ni([15]aneS_3)]^2+ forms six-coordinate adducts with Cl^-, CH_3CN and pyridine. An electrochemical study of the complexes [Ni([9]aneS_3)(PP)]^2+ is given. The reduction products [Ni([9]aneS_3)(PP)]^+ and [Ni([9]aneS_3)(PP)]^0 can be generated reversibly from the Ni^II precursors, and were assigned as square-pyramidal d^9 Ni^I and tetrahedral d^10 Ni^0 species respectively. The reaction of [Ni([9]AneS_3)(PP)]^+ with CO is investigated. The characterisation of the redox products of [Ni([9]aneS_3)_2]^2+ is also discussed: [Ni([9]aneS_3)_2]^3+ was formulated as an octahedral d^7 Ni^III complex. The synthesis and characterisation of the compounds [Rh([9]aneS_3)-(L)(L')]^+ (L,L' = C_2H_4, 0.5C_7H_8, 0.5C_8H_12, 0.5C_4H_6, CO, PR_3) is given. Single crystal x-ray analyses on four of these complexes show them to adopt a variety of five-coordinate geometries. The [Rh([9]aneS_3)]^+ fragment is shown to have high electrophilic character. Reactions of [Rh([9]aneS_3)-(L)(L')]^+ with electrophilic and nucleophilic substrates are discussed. The preparation and properties of the complexes [Ir([9]aneS_3)(L)(L')]^+ (L,L' = C_2H_4, C_8H_14, 0.5C_8H_12, 0.5C_4H_6, CO, PPh_3) are described. Three of these species are shown to have five-coordinate structures by x-ray crystallography. The electronic character of the species [M([9]aneS_3)(L)_2]^+ (M &61 Rh, Ir; L = C_2H_4, 0.5C_4H_6) is discussed. X-ray structural analyses of [16]aneS_4 show this ligand to adopt a rectangular conformation in the solid state. Molecular mechanics calculations on [16]aneS_4 and C_16H_32 are presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available