The chemical characteristics of transition-metal organometallic nitrosyl complexes

• Main Author: Nurse, Charles Richmond
• Language: English
• Published: University of British Columbia 2010
• Online Access: http://hdl.handle.net/2429/25654

The reactions of (n⁵-C₅H₅)Cr (CO)₂ (NO) with halogens result in either (n⁵-C₅H₅)Cr (CO)₂X (NO) (X=C1 or Br) or [(n⁵-C₅H₅)Cr (NO)I]₂. Further treatment of the iodo-complex with excess I₂ or NO leads to the formation of (n⁵-C₅H₅)Cr (NO)₂I. This complex also results from thermal decomposition of the dimericiodo—complex. Reaction of (n⁵-C₅H₅)Cr (CO)(NO)(PPh₃) with halogens, or cleavage of the iodide bridges in [(n⁵-C₅H₅)Cr (NO)I]₂ with Lewis bases, results in a series of stable paramagnetic complexes, (n⁵-C₅H₅)Cr (NO)LX (L=Lewis base X=halide). In addition, the reactions of halogens with (n⁵-C₅Me₅)M(CO)₂(NO) (M=Cr, Mo and W) are described. Reaction of [(n⁵-C₅H₅)W (NO)I₂]₂ with thallium or sodium cyclopentadienide results in the electron—rich complexes (C₅H₅)₂W(NO)X (X=1 or N¹- C₅H₅). The fluxional behaviour and instantaneous molecular structures of these complexes are discussed. Reduction of [(n⁵-C₅H₅)Mo (NO)I₂]₂ with Na/Hg in the presence of non—cyclic conjugated dienes produces (n⁵-C₅H₅)Mo (NO) (n⁴-diene); the diene is coordinated in the rare s—trans conformation. An unusual solvent control is observed in the reaction of (C₅H₅)₂Mo(NO)I with the silver (I) salts, AgBF₄, or AgSbF₆. In CH₃CN, salts of the [(C₅H₅)₂Mo(NO)CH₃CN)]⁺ cation are formed in high yield, while in aqueous acetone the trimetallic species, [ {(n⁵-C₅H₅)Mo (NO) (OH)} ₃O]Y (Y=BF₄, of SbF₆), result. In CH₂Cl₂, a non-coordinating solvent, the insoluble adducts, (C₅H₅)₂Mo(NO)I.AgY (Y=BF₄ or SbF₆), precipitate in high yield, the organometallic reactant presumably functioning as a "soft" Lewis base. Reaction of (C₅H₅)₂Mo(NO)I with AICI₃ effects halide abstraction to give the unsolvated cation, [(n⁵-C₅H₅)₂Mo (NO)]. Addition of the strong acids HBF₄.OMe₂ or HPF₆(aq) to a CH₂Cl₂ solution of (n⁵-C₅H₄Me)₃Mn₃(NO)₄ (1)results in the reversible formation of the novel hydroxyimido complexes, [(n⁵-C₅H₄Me)₃Mn₃(NO)₃(NOH) ]Y (2a, Y=BF₄; 2b, Y=PF₆). Further treatment with acid induces reduction of the N-O bond to give [(n⁵-C₅H₄Me)₃Mn₃(NO)₃(NH)]Y (3a, Y=BF₄; 3b, Y=PF₆). X-ray crystallographic analyses of 2a and 3b have been performed in order to characterise the novel (μ₃-NOH) and (μ₃—NH) groups. The trimetallic imido complex is also one of the products of the reaction of [(n⁵-C₅H₄Me)Mn(CO)(NO)]₂ with HBF₄.OMe₂. In addition, the new amido complex, [(n⁵-C₅H₄Me)₂Mn₂(NO)₂(CO)(NH₂)]BPh₄, can be isolated from the reaction mixture after treatment with aqueous NaBPh₄. === Science, Faculty of === Chemistry, Department of === Graduate