Nitrosyl complexes of vanadium, niobium, tantalum, tungsten, and iron

Treatment of V(CO)₅(NO) with trimpsi (trimpsi = BuSi(CH₂PMe₂)₃), followed by heating in THF, generates (trimpsi)V(CO)₂NO in moderate yields. (trimpsi)V(CO)₂NO has been studied by X-ray crystallography, ⁵¹V{¹H} NMR spectroscopy, and cyclic voltammetry. (trimpsi)V(CO)₂NO can be oxidised by the reaction with [Cp₂Fe] [BF₄], generating [(trimpsi) V(CO)₂NO] [BF₄]. Treatment of (trimpsi) V(CO)₂NO with one equiv of PhICl₂, Br₂, or I₂, or two equiv of C1NO, generates (trimpsi)VX₂ (NO) (X = CI, Br, I) in good yields. Treatment of (trimpsi)M(CO)₂NO (M = Nb, Ta) with I₂, followed by addition of excess PMe₃, provides (trimpsi)MI₂(NO)(PMe₃) in low to moderate yields. The reaction between (trimpsi)M(CO)₂NO (M - Nb, Ta) with one equiv of C1NO provides (trimpsi)M(NO) ₂Cl. These two complexes are thermally sensitive and have only been characterised by low-temperature IR and NMR spectroscopies. Treatment of (trimpsi)VCl₂ (NO) with p-toluic acid and Proton Sponge provides (trimpsi)V(O₂CPh-4-Me)₂(NO) in moderate yield. Alternatively, treatment of (trimpsi) V(CO)₂NO with benzoyl peroxide also generates a carboxylate complex, namely (trimpsi)V(O₂CPh)₂(NO). The reaction between (trimpsi)VCl₂(NO) and 0.5 equiv of MgR₂x(dioxane) (R = CH₂SiMe₃, CH₂CMe₃, Me) forms (trimpsi)V(R)Cl(NO) in good yields. Several attempts to form complexes of the type (trimpsi)VR₂(NO) have been unsuccessful. Treatment of [V(NO)₃Cl2][sub n] with excess THF generates mer-(THF)₃VCl₂(NO) in good yield. The reaction of mer-(THF)₃VCl₂(NO) with excess MeCN generates fac- (MeCN)₃VCl₂(NO). Both complexes have been characterised by X-ray crystallography. The reaction of VCI₄ with NO has been found to generate [NO][VCl₅] and VCI₃. [NO][VCl₅] can also be formed by the reaction of VC1₄ and C1NO. Treatment of [NO][VCl₅] with excess [NEt₃CH₂Ph][Cl] generates [NEt₃CH₂Ph]₂[VCl₆] in moderate yield, while exposure of a DME solution of [NO][VCl₅] to air generates (DME)VC1₂(O)(μ-O)V(O)C1₂(DME). The reaction between Fe(NO)₃Cl and [Ag][X] (X = BF₄, PF₆) forms Fe(NO)₃(η¹-X) in moderate yields. Alternatively, Fe(NO)₃( η¹-X) can also be formed by the action of [NO][X] upon Fe powder. Fe(NO)₃( η¹-BF₄) has been characterised by X-ray crystallography. During the course of this research [Fe(NO)₃(EtCN)][PF₆] and [Fe(NO)₃(μ-PO₂F₂)Fe(NO)₃][PF₆] have also been isolated and structurally characterised. The iron trinitrosyl complexes exhibit bent nitrosyl linkages and a molecular orbital rationale is given to explain these metrical parameters. The solid-state molecular structure of another trinitrosyl complex, namely fac-W(NO)₃C1₃, was also determined. fac-W(NO)₃Cl₃ exhibits linear nitrosyl ligands, and a rationale is provided to explain the difference between the iron and tungsten cases.Science, Faculty ofChemistry, Department ofGraduat