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Pyrazolyl based ligands in transition metal complexes

University of British Columbia

Several uninegative/ multidentate pyrazolyl based ligands were synthesized [eg. HBPZ₃₋, HBpz”₃₋, MeGapz₃₋/ MeGapz” ₃₋, H2BpZ₂₋/ Me2Bpz₂₋/ Me2GapZ₂₋/ Me2Gapz"₂₋/ Me₂Gapz(OCH₂CH₂NH₂)⁻Me₂Gapz(OCH₂CH₂CH=CH₂)⁻ ; pz pyrazolyl/ pz" = 3, 5 dimethylpyrazolyl]. These ligands were reacted with the sterically hindered metal complex, HBpz*₃MCl (M = Co, Ni; pz* = 3-iPr-4-Br-pyrazolyl) and the mixed-ligand transition metal complexes of general formulae, HBpz*₃ML, were isolated. The X-ray crystal structure of one such complex, HBpz*₃Nipz"₃BH was determined showing a near octahedral arrangement of ligands about the nickel centre. The electronic spectra of the nickel complexes were recorded and compared to predicted transitions. The electronic spectra of the four coordinate nickel complex, HBpz*₃NiCl, fit a d⁸, tetrahedral, ligand field model. The six coordinate complexes, HBpz*₃NiL (L = HBPZ₃, HBpz"₃, MeGapz₃, MeGapz”₃), fit a d⁸, octahedral, ligand field model. The unsymmetrical pyrazolylgallate ligands were reacted with the rhodium dimer [Rh(CO)₂CI]₂ to give the square planar complexes, LRh(CO) [L = Me2Gapz(OCH₂CH₂NH₂), Me₂Gapz(OCH₂CH₂CH=CH₂)]. These rhodium[I] complexes appeared to undergo oxidative additions of Mel, allylbromide and I₂. Furthermore these rhodium[I] complexes appeared to bind the small gas molecules, CO and ethene. A number of heterobimetallic complexes, with direct metal-metal bonds, were prepared and isolated from the reaction of the molybdenum anion, HBpz"₃(CO)₃MO⁻ with the transition metal halides, [CuPPb₃Cl]₄, SnR₃Cl (R = Me, Ph) and GePh₃Cl.

Text

2010-08-22

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http://hdl.handle.net/2429/27610

Chemistry

University of British Columbia

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