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Copper(I) and copper(II) complexes with tetradentate tripod ligands
O,-UTILIZATION & PROCESSING
327
LO57
SYNTHETIC MODELS FOR THE ACTIVE SITE OF HEMOCYANIN. T. N. Sorrel& M. L. Garrity, J. Ft. Richards, V. A. Vankai, Department of Chemistry, University of North Caroina, Chapel Hill, NC 27599-3290, USA. The purpose of modeling studies is to confirm the proposed structures for the active site in hemocyanin and to understand the intrinsic properties of the copperdioxygen interaction. We have synthesized a number of chelating ligands having imidazole residues coordinated to copper. Reaction of the copper(l) derivatives with dioxygen generates adducts which are stable at low temperatures. In certain cases, hydroxylation of an endogenous arene group is observed. A comparison of the observed reactivity of imidazole, benzimidazole, pyridine, pyrazole, and mixed-ligand complexes has been accomplished to help probe the important features of the hemocyanin active site.
LO58
COPPER(I) AND COPPER(R) COMPLEXES WITH TETRADENTATE TRIPOD LIGANDS. Jean P. Helin Zoltan Tyeklar and Kenneth D. Karlin. Dept. of Chemistry, State University of New York (SUNY) at Albany, Albany, NY 12222 Studies on mononuclear Cu(I) and Cu(II) cneters contianing aromatic nitrogen donor ligands are of interest because of the presence of Type 1 and Type 2 acitve sites in ‘blue’ copper proteins, nonblue copper oxidases and NOx reductases. To model sites we are studing a large series of tripodal tetradentate ligand [(PY-(CH&N-[(CH&,D][(CH2)1D’], where n, m and 1 are 1 or 2, PY = 2-pyridyl and D and D’ are PY and/or lMe-24midazolyl and/or 2-quinolinyl. Copper(I) and copper(R) complees with these ligands have been synthesized and characterized. UV-vis, EPR spectroscopic and electrochemical comparisons, along with sutides of the reactions of the Cu(1) derivatives with dioxygen, will be presented.
LO59
A CARBON-MONOXIDECOMPLEXOF REDUCED DOPAMINE-g-HE (DBH). N. J. Blackburn, K. Seagraves, & R. Shigeta, Oregon Graduate Center, Beaverton, OR 97006-1999, USA. A CO complex of reduced DBH has been prepared and characterized using absorption edge and FTIR spectroscopies. Kinetics of inhibition of DBH by CO are competitivewith the substrate 0,, indicating that 0, and CO compete for mutually exclusive binding sites on the protein. The value of v(C0) = 2089 cm-' is greater than those reported for hemocyanins or the CO complex of of cytochrome oxidase, and suggests that one of the histidines has %e en replaced by a less basic ligand. Preliminary measurements of the stoichiometryof CO binding indicate -0.5 mole CO bound Per CU. This result provides strong evidence for inequivalence of the Cu centers in reduced DBH and suggests that 0 binding and reduction occur at only one of the 2 Cu’s per catalytik unit.
327
LO57
SYNTHETIC MODELS FOR THE ACTIVE SITE OF HEMOCYANIN. T. N. Sorrel& M. L. Garrity, J. Ft. Richards, V. A. Vankai, Department of Chemistry, University of North Caroina, Chapel Hill, NC 27599-3290, USA. The purpose of modeling studies is to confirm the proposed structures for the active site in hemocyanin and to understand the intrinsic properties of the copperdioxygen interaction. We have synthesized a number of chelating ligands having imidazole residues coordinated to copper. Reaction of the copper(l) derivatives with dioxygen generates adducts which are stable at low temperatures. In certain cases, hydroxylation of an endogenous arene group is observed. A comparison of the observed reactivity of imidazole, benzimidazole, pyridine, pyrazole, and mixed-ligand complexes has been accomplished to help probe the important features of the hemocyanin active site.
LO58
COPPER(I) AND COPPER(R) COMPLEXES WITH TETRADENTATE TRIPOD LIGANDS. Jean P. Helin Zoltan Tyeklar and Kenneth D. Karlin. Dept. of Chemistry, State University of New York (SUNY) at Albany, Albany, NY 12222 Studies on mononuclear Cu(I) and Cu(II) cneters contianing aromatic nitrogen donor ligands are of interest because of the presence of Type 1 and Type 2 acitve sites in ‘blue’ copper proteins, nonblue copper oxidases and NOx reductases. To model sites we are studing a large series of tripodal tetradentate ligand [(PY-(CH&N-[(CH&,D][(CH2)1D’], where n, m and 1 are 1 or 2, PY = 2-pyridyl and D and D’ are PY and/or lMe-24midazolyl and/or 2-quinolinyl. Copper(I) and copper(R) complees with these ligands have been synthesized and characterized. UV-vis, EPR spectroscopic and electrochemical comparisons, along with sutides of the reactions of the Cu(1) derivatives with dioxygen, will be presented.
LO59
A CARBON-MONOXIDECOMPLEXOF REDUCED DOPAMINE-g-HE (DBH). N. J. Blackburn, K. Seagraves, & R. Shigeta, Oregon Graduate Center, Beaverton, OR 97006-1999, USA. A CO complex of reduced DBH has been prepared and characterized using absorption edge and FTIR spectroscopies. Kinetics of inhibition of DBH by CO are competitivewith the substrate 0,, indicating that 0, and CO compete for mutually exclusive binding sites on the protein. The value of v(C0) = 2089 cm-' is greater than those reported for hemocyanins or the CO complex of of cytochrome oxidase, and suggests that one of the histidines has %e en replaced by a less basic ligand. Preliminary measurements of the stoichiometryof CO binding indicate -0.5 mole CO bound Per CU. This result provides strong evidence for inequivalence of the Cu centers in reduced DBH and suggests that 0 binding and reduction occur at only one of the 2 Cu’s per catalytik unit.