Vibrational studies of (MLX5)n- type compounds
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The work presented in this thesis covers an infrared vibrational and X-ray structural study of the metal ion-halogeno bond in complexes of the type, (a) A₂[MLX₅ ] (A⁺ includes K⁺, Rb⁺, Cs⁺; M includes Cr(V), Mo(V), Tc(IV), Tc(V), Ru(III), Ru(IV), W(V) and Re(V); L includes o²-, OH-, Cl-, Br-, CO, H₂o; and includes Cl- and Br-) and (b) solid solutions K₂[ (Pt/M) Cl₆] (M (IV) = Ir (IV), Os (IV) , Re (V)). Cell parameters have been determined at 296K for all complexes (except K₃) RuCl₆] and K₂[Ru (CO) Cl₅]), while some have been calculated from data collected at 186K. The crystal structure of cs₂[MoOBr₅] has been completed. Infrared spectra have been recorded over two ranges, 4000 - 400 cm-¹and 400- 40 cm-¹, with those over the latter region being determined on samples held at 296, 237 and 179K. The experimental work divides into three principal sections. (a) Studies of complexes of ruthenium (III) and (IV). Monomeric An[RuX₅L] (n = 2,3; A⁺ includes K⁺, Rb⁺, Cs⁺; X- = Cl-, Br-; L includes co, H₂O, Cl-, B-r and dimeric A₃[Ru ₂x₉] (A⁺= K⁺, Rb⁺, Cs⁺; X-= Cl-, Br-) complexes have been studied. The dimers are new complexes and results obtained imply the existence of a metal ionmetal ion bond. (b) Studies of solid solutions K₂[(Pt/M)Cl₆] (M(IV) = Ir(IV), Os(IV), Re(IV)). Infrared, magnetic and structural properties were investigated and the n-bond component of the metal ion-chloro bond has been shown to have significant effects on the physical properties of the K₂[MCl₆] (M(IV) = Ir (IV), Os (IV) , Re(IV)) complexes. (c) Studies of complexes A₂[MLX₅] (A⁺ includes K⁺, Rb⁺, Cs⁺; M(n) = Cr (V), Mo (V), W (V), Tc (V), Re (V), Tc(IV); and L includes O²- and OH-). Again infrared and structural studies have been completed. The results from all of these sections give information on the properties of the metal ion-halogeno ligand bond and in particular show the manner in which this bond may adapt to environmental changes brought about by, (a) varying the counter cations, (b) altering the volume within the crystal lattice available to the anion [MLX₅]²-, (c) variation of the sixth ligand L and (d) varying oxidation states of the metal ion. The adaptability of the bond is considered to be due to the halogeno ligands being capable of both donating and accepting electrons to and from the metal ion.