yilma gultneh - Academia.edu (original) (raw)
Papers by yilma gultneh
Preparation of phosphites, metal complexes, oxides, selenides, and borohydride derivatives of pho... more Preparation of phosphites, metal complexes, oxides, selenides, and borohydride derivatives of phosphites Results and Discussion CATALYTIC ISOMERIZATION OF 3-BUTENENITRILE Introduction Mechanism of catalytic olefin isomerization Experimental Materials Techniques Results and Discussion Effect of solvent Effect of strength of the acid Effect of acid to complex ratio 101 Effect of ligand basicity 111 Effect of isomerism due to configuration at phosphorus 113 Effect of substituants on the 1,3,2dioxaphosphorinane ligand 113 Effect of the presence of added excess ligand Effect of substitution of oxygen in the ring by carbon 127 Asymmetric catalytic isomerization using Ni((-)-lla)A/FiCCOOH in benzene at 25''C 132 NiL^/Lewis Acid Systems 139 HYDROCYANATION OF OLEFINS 151 Introduction 151 Experimental Materials 160 Preparation 160 Catalysis procedure 161 iii Page Results and Discussion 164 Hydrocyanation of various olefins 164 Relative rates of hydrocyanation as a function of excess ligand to NiL4 ratio Effect of ZnCl2:NiL4 ratio on rate of catalytic hydrocyanation of norbomene Asymmetric hydrocyanation of norbomene and bicyclo[2.2.2]octene using chiral NiL^ complexes Catalytic asymmetric hydrocyanation of norbomene and bicyclo [2.2.2] octene by chiral mixed ligand Ni(0) complexes CATALYTIC HYDROGENATION OF OLEFINS xiii
![Research paper thumbnail of μ-Acetato-aqua-μ-(5-bromo-2-{1,3-bis[2-(5-bromo-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}phenolato)methanoldinickel(II) methanol disolvate monohydrate](https://attachments.academia-assets.com/74508029/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2011
l-Acetato-aqua-l-(5-bromo-2-{1,3-bis[2-(5-bromo-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}p... more l-Acetato-aqua-l-(5-bromo-2-{1,3-bis[2-(5-bromo-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}phenolato)methanoldinickel(II) methanol disolvate monohydrate
![Research paper thumbnail of Synthesis and Structure of a Binuclear Cu(II) Complex of 1,3- bis [N,Nbis(2-picolyl)amino]propan-2-ol](https://attachments.academia-assets.com/47825010/thumbnails/1.jpg)
](International Journal of Molecular Sciences, 2006
The synthesis and crystal structure of Cu(II) complex of a binucleating tridentate ligand 1,3-bis... more The synthesis and crystal structure of Cu(II) complex of a binucleating tridentate ligand 1,3-bis [N,N-bis(2-picolyl)amino]propan-2-ol (I) is being reported. The two chelating bispicolylamine arms in I are tethered by a 2-hydroxypropyl group with Cu(II) coordinating in a slightly distorted square planar geometry to give [Cu 2 (I)(OH 2 )(Cl)](ClO 4 ) 3 ·2H 2 O (II). The crystal data for II: Triclinic, space group Pī with cell dimensions of a = 13.345 (4) Å, b = 13.873 (4) Å, c = 12.867 (2) Å, α = 111.68 (2)°, β = 100.34 (2)°, γ = 65.83 (2)°, V = 2018.4 (9) Å 3 , F.W. = 962.46, ρ calc = 1.583 g cm -3 for Z = 2, µ = 13.93 cm -1
Journal of The American Chemical Society, 1991
ENDOR (electron nuclear double resonance) gave hyperfine couplings to nitrogen(s) on the bis(r-ox... more ENDOR (electron nuclear double resonance) gave hyperfine couplings to nitrogen(s) on the bis(r-oxo)-Mn1ILMdv complexes of CYCLAM (1,4,8,11-tetraazacyclotetradecane) and TMPA (tris(2-methylpyridy1)amine). PFSEPR (pulse field-sweep EPR) gave nitrogen hyperfine couplings consistent with the ENDOR results. The nitrogen hyperfine couplings from ENDOR were 9.2 MHz for CYCLAM and 11.2 MHz for TMPA. We provide justification that these couplings are due to a Fermi contact interaction with nitrogen 2s electron spin density at the axial nitrogens on the MnlI1, where this electron spin is contained in an antibonding e orbital along the MnI%itrogen bond. The relevant axial nitrogen ligands are secondary amine nitrogens in the case of CYeLAM and pyridyl nitrogens in the case of TMPA. Compared to quadrupolar couplings from unligated secondary amine or pyridine, the quadrupolar interaction for both types of nitrogen indicated a significant decrease in electric field gradient at the nitrogen nucleus due to interaction of the nitrogen lone pair with the manganese. Proton ENDOR showed exchangeable protons associated with the CYCLAM complex but not with the TMPA complex. We assign these exchangeable CYCLAM protons on the basis of their large 6.7-MHz hyperfine coupling as exchangeable protons on the secondary amine nitrogens at the Mnlll.
Journal of The Chemical Society, Chemical Communications, 1984
Hydrogen peroxide reacts with a Cu II complex of a m-xylyl binucleating ligand with concomitant h... more Hydrogen peroxide reacts with a Cu II complex of a m-xylyl binucleating ligand with concomitant hydroxylation to give a phenoxo-bridged complex (previously found as the product of the reaction of dioxygen with the Cu I analogue) whereas a newly synthesized ...
Inorganic Chemistry, 1984
Caution! While we have experienced no explosions during the handling of small quantities of these... more Caution! While we have experienced no explosions during the handling of small quantities of these materials, many structurally similar N-halo compounds are known to be powerful explosives. Due caution must be exercised while conducting experiments such as those described here. In a typical reaction, CF,=NCl, Br,, and CsF were allowed to react in a 100-mL glass reactor containing a Teflon-coated magnetic stirring bar at 22 OC in the absence of light. The mixture was stirred for an appropriate time, and the products were then separated by pumpng through a series of cold traps. Essentially pure CF3NClBr and CF3NBr, were then obtained by brief treatment with excess C2H4 at 22 OC to remove unreacted Br,, followed by reseparation. The reactions are summarized in .
Journal of The Chemical Society, Chemical Communications, 1987
... Kenneth D. Karlin,* Richard W. Cruse, and Yilma Gultneh Department of Chemistry, State Univer... more ... Kenneth D. Karlin,* Richard W. Cruse, and Yilma Gultneh Department of Chemistry, State University of New York (SUNY) at Alban y, Alban y, New York 12222 ... Acta, 1984,91, LSL 7 ; (d) NJ Blackburn, KD Karlin, M. Concannon, J. C. Hayes, Y. Gultneh, and J. Zubieta, J. Chem. ...
Inorganic Chemistry, 1992
... Auteur(s) / Author(s). KARLIN KD ; TYEKLAR Z. ; FAROOQ A. ; HAKA MS ; GHOSH P. ; CRUSE RW ; G... more ... Auteur(s) / Author(s). KARLIN KD ; TYEKLAR Z. ; FAROOQ A. ; HAKA MS ; GHOSH P. ; CRUSE RW ; GULTNEH Y. ; HAYES JC ; TOSCANO PJ ; ZUBIETA J. ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). Johns Hopkins univ., dep. ...
Inorganic Chemistry, 1992
The binding of 0 2 to copper(1) and its subsequent reactivity is important in a variety of chemic... more The binding of 0 2 to copper(1) and its subsequent reactivity is important in a variety of chemical and biological processes. We previously studied functional models of hemocyanins (arthropodal and molluscan 0 2 carriers) involving a class of 0 2 adducts [Cu~(Nn)(02)]2+ (2) et al. Inorg. Chem. 1992, 31, 1436-1451, where Nn are dinucleating ligands which employ two tridentate bis(2-pyridylethy1)amine (PY2) moieties, connected by a variable alkyl chain. Here, we report studies of O2 reactivity using R-substituted PY2 tridentate ligands and derived mononuclear Cu(1) precursor complexes [Cu(RPY2)]+ (3a, R = Me; 3b, R = PhCH2; 3c, R = Ph). The X-ray structure of the nearly "T-shaped" complex 3c(PF6) (CZOHZICUN~FSP) is reported; it crystallizes in the space group P2]/n, a = 10.037 (4) A, b = 14.406 (4) A, c = 15.210 (5) A, j 3 = 105.99 (3)O, D c a l~ = 1.61 g/cm', 2 = 4.
Journal of Chemical Education, 1985
Interest in studies of the reactivity of dioxygen with copper ion complexes arises from the fact ... more Interest in studies of the reactivity of dioxygen with copper ion complexes arises from the fact that copper-containing enzymes in biological systems ( 1 4 ) and-copper compounds in synthetic systems ( 6 8 ) have been established to be essential catalysts in oxidation and 02-mediated reactions. In order to deduce the structures and mechanism of action of the rotei in-active sites. a maior focus of research has utilized tke biomimetic apprbach (9-11); this approach involves the develo~ment of chemical model svstems that mimic the physicochemical and functional properties ot'the biological oxyeen carriers (which in living svsrems bind 0.1 reversibly andtransport it), oxygenases (;which incorporate an oxygen atom from 0 2 into biological substrates), and oxidases (which reduce Ozto hydrogen peroxide or water). In this article, we will focus on studies done in modeling the copper centers in the proteins hemocyanin (Hc) (a dioxygen carrier), tyrosinase (Tyr), and dopamine heta-hydroxylase (DbH) (mono-oxygenases),
Journal of The American Chemical Society, 1984
... a = 18.221 (3) A, b = 13.323 (3) A, c = 18.643 (4) A, and @ = 102.39 (2)'. T... more ... a = 18.221 (3) A, b = 13.323 (3) A, c = 18.643 (4) A, and @ = 102.39 (2)'. The structural features of these complexes are compared to those of other related compounds and to the active sites of the copper proteins. The biological relevance of the monooxygenase model system is ...
Journal of The American Chemical Society, 1987
J. A m . Chem. SOC. and the macrocycle is C(16)-C(b4) = 3.846 ( 5 ) %.; all other distances are l... more J. A m . Chem. SOC. and the macrocycle is C(16)-C(b4) = 3.846 ( 5 ) %.; all other distances are larger. Thus the bridging alkyl chains of isomers I1 and I11 are not expected to interfere significantly with the binding of axial ligands, although they may interfere with free rotation of bound axial ligands about the M-L bond. Preliminary N M R investigations of low-spin Fe(II1) complexes of hexyl I1 and
Journal of The American Chemical Society, 1984
... Dioxygen Binding to a Structurally Characterized Phenoxide-Bridged Copper( I) Complex Kenneth... more ... Dioxygen Binding to a Structurally Characterized Phenoxide-Bridged Copper( I) Complex Kenneth D. Karlin,* Richard W. Cruse, Yilma Gultneh, Jon C. Hayes, and Jon Zubieta Department of Chemistry Slate University of ... (7) Blackburn, NJ; Karlin, K. D.; Concannon, M.; Hayes, J ...
Journal of The American Chemical Society, 1985
... Reversible O2 and CO Binding by a New Series of Binuclear Copper(1) Complexes Kenneth D. Karl... more ... Reversible O2 and CO Binding by a New Series of Binuclear Copper(1) Complexes Kenneth D. Karlin,* Michael S. Haka, Richard W. Cruse, and Yilma Gultneh Department of Chemistry, State University of New York (SUNY ... 5) Blackburn, N. J.; Karlin, K. D.; Concannon, M.; Hayes ...
Journal of The American Chemical Society, 1982
Inorganica Chimica Acta, 1983
... of a Model Copper Monooxy-genase Reaction KENNETH D. KARLIN*, JON C. HAYES, RICHARD W. CRUSE,... more ... of a Model Copper Monooxy-genase Reaction KENNETH D. KARLIN*, JON C. HAYES, RICHARD W. CRUSE, YILMA GULTNEH, JOHN P ... N3 Models for Hemocyanin THOMAS N. SORRELL*, DONALD L. JAMESON, MITCH-ELL R. MALACHOWSKI and ANDREW S. BOROVIK ...
Inorganic Chemistry, 1992
The dinucleating phenol ligand LOH (LOH = 2,6-bis((bis(2-(2-pyridyl)ethyl)amino)methyl)phenol(l))... more The dinucleating phenol ligand LOH (LOH = 2,6-bis((bis(2-(2-pyridyl)ethyl)amino)methyl)phenol(l)) is reacted with Mn(C104)y6H20 in the presence of excess acetate anion and a base (NEt3) in methanol to produce the dinuclear Mn112 complex [Mn2(LO)(OAc)z]C104 (5) which crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 11.227 (3) A, b = 21.815 (8) A, c = 17.731 (7) A, a = 90.00 (3)O, B = 102.45 (3)O, and y = 90.00 (3)O, with four molecules per unit cell. The structure shows that two acetate anions and a phenoxy oxygen bridge the manganese ions. The [Mn2(LO)(p-OAc)2]+ cation has a noncrystallographic Cz axis with the two Mn(I1)
Inorganic Chemistry, 1985
Spectra were recorded with a Nicolet NT-200 WB spectrometer, as previously d e s~r i b e d . '~, ... more Spectra were recorded with a Nicolet NT-200 WB spectrometer, as previously d e s~r i b e d . '~, '~ Results and Discussion. The ,H N M R spectra for cis-and . Carboxyl coordination of nicotinate-2-d gives rise to a distinctly narrower resonance centered at ca. +9 ppm ( summarizes the electronic spectra of cis-and trans-H[Cr(mal),(nic-N),], bands V and IV, respectively. The ligand field spectra are consistent with a Cr(N2-04) formulation by comparison with the previously characterized Cr(N,-0,) complexes listed in . The striking similarity of band maxima and molar absorptivities for band IV and previously characterized tran~-Li[Cr(mal)~(py),] l 3 is the basis for the assignment of band IV as ~rans-H[Cr(mal)~(nic-N)~]. Therefore, since band V is also a bis(ma1onato) bis(nicotinic acid) complex, it must be assigned the cis configuration as this is the only other geometrical isomer possible. The larger molar absorptivities for the d-d transitions of this isomer are consistent with the cis assignment, due to the lower symmetry associated with the cis relative to the trans configuration. The geometrical assignments could be made directly from ,H N M R spectra for the complexes with deuteriumlabeled malonate,13 but so far we have not succeeded in obtaining the desired spectra. Deuteration of the coordinated malonates was carried out as described previously for tran~-Li[Cr(mal)~-(py),]13 and was confirmed by IR spectroscopy. Apparently, the malonate protons (deuterons) undergo facile exchange in solution. This may be due to intramolecular general-base catalysis promoted by the pyridyl carboxyl group, since this facile exchange is not observed in trans-Li[Cr(mal)2(py)z], which was assigned the trans configuration by malonate ,H N M R studies.13
![Research paper thumbnail of Di-μ-perchlorato-bis{μ-2-[(2-pyridyl)methylaminomethyl]phenolato)dicopper(II) acetonitrile disolvate](https://attachments.academia-assets.com/47825056/thumbnails/1.jpg)
](Acta Crystallographica Section E-structure Reports Online, 2009
Key indicators: single-crystal X-ray study; T = 200 K; mean (C-C) = 0.006 Å; R factor = 0.078; wR... more Key indicators: single-crystal X-ray study; T = 200 K; mean (C-C) = 0.006 Å; R factor = 0.078; wR factor = 0.199; data-to-parameter ratio = 31.4.
 (LOH = 2,6-bis{bis(2-(2-pyridyl)ethyl)aminomethyl}-4-methylphenol): Substituent effects](https://attachments.academia-assets.com/47825049/thumbnails/1.jpg)
](Inorganica Chimica Acta, 2006
The synthesis, structure and characterization of the dinuclear Mn(II) complex [Mn 2 (LO)(l-OAc) 2... more The synthesis, structure and characterization of the dinuclear Mn(II) complex [Mn 2 (LO)(l-OAc) 2 ](ClO 4 ) (1) where LOH = 2,6-bis-{bis(2-(2-pyridyl)ethyl)aminomethyl)}-4-methylphenol are reported. The reaction of Mn(ClO 4 ) 2 AE 6H 2 O with the dinucleating ligand LOH and H 3 CCOONa in the presence of NEt 3 in dry, degassed methanol and under an argon atmosphere, yields 1 as a colorless powder. The crystal structure of 1, determined by X-ray diffraction methods, shows a dinuclear Mn(II) complex in which two Mn(II) ions, each in six-coordinate approximate octahedral coordination, are bridged by the phenolate oxygen of LO À and by two acetate ions in a syn,syn-1,3-bridging mode. The Mn-Mn distance is 3.557(1) Å and Mn-O phenolate -Mn angle is 112.50(9)°. Cyclic voltammetry of 1 in acetonitrile solution shows a quasi-reversible wave at E 1/2 = 0.65 V, for the Mn 2 (II,II)/Mn 2 (II,III) redox process, and an irreversible oxidation peak at E p,c = 1.22 V versus Ag/AgCl for the Mn 2 (II,III) to Mn 2 (III,III) oxidation process. Controlled potential electrolysis of 1 in acetonitrile solution at 0.85 V (versus Ag/AgCl) takes up 1 F of charge per mole of 1 to yield a brown solution of the Mn 2 (II,III) state of the complex, which, however, is unstable and reverts back to the Mn 2 (II,II) state in solution at room temperature. Least square fitting of the variable temperature magnetic susceptibility measurements on powdered sample of 1 is obtained with g = 1.888, J = À2.75 cm À1 , Par = 0.008, TIP = 0. The low ÀJ value and the room temperature calculated magnetic moment of the complex (5.30 BM per Mn(II)), which is less than the spin-only moment of Mn(II), show that the two Mn(II) ions are weakly antiferromagnetically coupled.
Preparation of phosphites, metal complexes, oxides, selenides, and borohydride derivatives of pho... more Preparation of phosphites, metal complexes, oxides, selenides, and borohydride derivatives of phosphites Results and Discussion CATALYTIC ISOMERIZATION OF 3-BUTENENITRILE Introduction Mechanism of catalytic olefin isomerization Experimental Materials Techniques Results and Discussion Effect of solvent Effect of strength of the acid Effect of acid to complex ratio 101 Effect of ligand basicity 111 Effect of isomerism due to configuration at phosphorus 113 Effect of substituants on the 1,3,2dioxaphosphorinane ligand 113 Effect of the presence of added excess ligand Effect of substitution of oxygen in the ring by carbon 127 Asymmetric catalytic isomerization using Ni((-)-lla)A/FiCCOOH in benzene at 25''C 132 NiL^/Lewis Acid Systems 139 HYDROCYANATION OF OLEFINS 151 Introduction 151 Experimental Materials 160 Preparation 160 Catalysis procedure 161 iii Page Results and Discussion 164 Hydrocyanation of various olefins 164 Relative rates of hydrocyanation as a function of excess ligand to NiL4 ratio Effect of ZnCl2:NiL4 ratio on rate of catalytic hydrocyanation of norbomene Asymmetric hydrocyanation of norbomene and bicyclo[2.2.2]octene using chiral NiL^ complexes Catalytic asymmetric hydrocyanation of norbomene and bicyclo [2.2.2] octene by chiral mixed ligand Ni(0) complexes CATALYTIC HYDROGENATION OF OLEFINS xiii
Acta Crystallographica Section E Structure Reports Online, 2011
l-Acetato-aqua-l-(5-bromo-2-{1,3-bis[2-(5-bromo-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}p... more l-Acetato-aqua-l-(5-bromo-2-{1,3-bis[2-(5-bromo-2-oxidobenzylideneamino)ethyl]imidazolidin-2-yl}phenolato)methanoldinickel(II) methanol disolvate monohydrate
International Journal of Molecular Sciences, 2006
The synthesis and crystal structure of Cu(II) complex of a binucleating tridentate ligand 1,3-bis... more The synthesis and crystal structure of Cu(II) complex of a binucleating tridentate ligand 1,3-bis [N,N-bis(2-picolyl)amino]propan-2-ol (I) is being reported. The two chelating bispicolylamine arms in I are tethered by a 2-hydroxypropyl group with Cu(II) coordinating in a slightly distorted square planar geometry to give [Cu 2 (I)(OH 2 )(Cl)](ClO 4 ) 3 ·2H 2 O (II). The crystal data for II: Triclinic, space group Pī with cell dimensions of a = 13.345 (4) Å, b = 13.873 (4) Å, c = 12.867 (2) Å, α = 111.68 (2)°, β = 100.34 (2)°, γ = 65.83 (2)°, V = 2018.4 (9) Å 3 , F.W. = 962.46, ρ calc = 1.583 g cm -3 for Z = 2, µ = 13.93 cm -1
Journal of The American Chemical Society, 1991
ENDOR (electron nuclear double resonance) gave hyperfine couplings to nitrogen(s) on the bis(r-ox... more ENDOR (electron nuclear double resonance) gave hyperfine couplings to nitrogen(s) on the bis(r-oxo)-Mn1ILMdv complexes of CYCLAM (1,4,8,11-tetraazacyclotetradecane) and TMPA (tris(2-methylpyridy1)amine). PFSEPR (pulse field-sweep EPR) gave nitrogen hyperfine couplings consistent with the ENDOR results. The nitrogen hyperfine couplings from ENDOR were 9.2 MHz for CYCLAM and 11.2 MHz for TMPA. We provide justification that these couplings are due to a Fermi contact interaction with nitrogen 2s electron spin density at the axial nitrogens on the MnlI1, where this electron spin is contained in an antibonding e orbital along the MnI%itrogen bond. The relevant axial nitrogen ligands are secondary amine nitrogens in the case of CYeLAM and pyridyl nitrogens in the case of TMPA. Compared to quadrupolar couplings from unligated secondary amine or pyridine, the quadrupolar interaction for both types of nitrogen indicated a significant decrease in electric field gradient at the nitrogen nucleus due to interaction of the nitrogen lone pair with the manganese. Proton ENDOR showed exchangeable protons associated with the CYCLAM complex but not with the TMPA complex. We assign these exchangeable CYCLAM protons on the basis of their large 6.7-MHz hyperfine coupling as exchangeable protons on the secondary amine nitrogens at the Mnlll.
Journal of The Chemical Society, Chemical Communications, 1984
Hydrogen peroxide reacts with a Cu II complex of a m-xylyl binucleating ligand with concomitant h... more Hydrogen peroxide reacts with a Cu II complex of a m-xylyl binucleating ligand with concomitant hydroxylation to give a phenoxo-bridged complex (previously found as the product of the reaction of dioxygen with the Cu I analogue) whereas a newly synthesized ...
Inorganic Chemistry, 1984
Caution! While we have experienced no explosions during the handling of small quantities of these... more Caution! While we have experienced no explosions during the handling of small quantities of these materials, many structurally similar N-halo compounds are known to be powerful explosives. Due caution must be exercised while conducting experiments such as those described here. In a typical reaction, CF,=NCl, Br,, and CsF were allowed to react in a 100-mL glass reactor containing a Teflon-coated magnetic stirring bar at 22 OC in the absence of light. The mixture was stirred for an appropriate time, and the products were then separated by pumpng through a series of cold traps. Essentially pure CF3NClBr and CF3NBr, were then obtained by brief treatment with excess C2H4 at 22 OC to remove unreacted Br,, followed by reseparation. The reactions are summarized in .
Journal of The Chemical Society, Chemical Communications, 1987
... Kenneth D. Karlin,* Richard W. Cruse, and Yilma Gultneh Department of Chemistry, State Univer... more ... Kenneth D. Karlin,* Richard W. Cruse, and Yilma Gultneh Department of Chemistry, State University of New York (SUNY) at Alban y, Alban y, New York 12222 ... Acta, 1984,91, LSL 7 ; (d) NJ Blackburn, KD Karlin, M. Concannon, J. C. Hayes, Y. Gultneh, and J. Zubieta, J. Chem. ...
Inorganic Chemistry, 1992
... Auteur(s) / Author(s). KARLIN KD ; TYEKLAR Z. ; FAROOQ A. ; HAKA MS ; GHOSH P. ; CRUSE RW ; G... more ... Auteur(s) / Author(s). KARLIN KD ; TYEKLAR Z. ; FAROOQ A. ; HAKA MS ; GHOSH P. ; CRUSE RW ; GULTNEH Y. ; HAYES JC ; TOSCANO PJ ; ZUBIETA J. ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). Johns Hopkins univ., dep. ...
Inorganic Chemistry, 1992
The binding of 0 2 to copper(1) and its subsequent reactivity is important in a variety of chemic... more The binding of 0 2 to copper(1) and its subsequent reactivity is important in a variety of chemical and biological processes. We previously studied functional models of hemocyanins (arthropodal and molluscan 0 2 carriers) involving a class of 0 2 adducts [Cu~(Nn)(02)]2+ (2) et al. Inorg. Chem. 1992, 31, 1436-1451, where Nn are dinucleating ligands which employ two tridentate bis(2-pyridylethy1)amine (PY2) moieties, connected by a variable alkyl chain. Here, we report studies of O2 reactivity using R-substituted PY2 tridentate ligands and derived mononuclear Cu(1) precursor complexes [Cu(RPY2)]+ (3a, R = Me; 3b, R = PhCH2; 3c, R = Ph). The X-ray structure of the nearly "T-shaped" complex 3c(PF6) (CZOHZICUN~FSP) is reported; it crystallizes in the space group P2]/n, a = 10.037 (4) A, b = 14.406 (4) A, c = 15.210 (5) A, j 3 = 105.99 (3)O, D c a l~ = 1.61 g/cm', 2 = 4.
Journal of Chemical Education, 1985
Interest in studies of the reactivity of dioxygen with copper ion complexes arises from the fact ... more Interest in studies of the reactivity of dioxygen with copper ion complexes arises from the fact that copper-containing enzymes in biological systems ( 1 4 ) and-copper compounds in synthetic systems ( 6 8 ) have been established to be essential catalysts in oxidation and 02-mediated reactions. In order to deduce the structures and mechanism of action of the rotei in-active sites. a maior focus of research has utilized tke biomimetic apprbach (9-11); this approach involves the develo~ment of chemical model svstems that mimic the physicochemical and functional properties ot'the biological oxyeen carriers (which in living svsrems bind 0.1 reversibly andtransport it), oxygenases (;which incorporate an oxygen atom from 0 2 into biological substrates), and oxidases (which reduce Ozto hydrogen peroxide or water). In this article, we will focus on studies done in modeling the copper centers in the proteins hemocyanin (Hc) (a dioxygen carrier), tyrosinase (Tyr), and dopamine heta-hydroxylase (DbH) (mono-oxygenases),
Journal of The American Chemical Society, 1984
... a = 18.221 (3) A, b = 13.323 (3) A, c = 18.643 (4) A, and @ = 102.39 (2)'. T... more ... a = 18.221 (3) A, b = 13.323 (3) A, c = 18.643 (4) A, and @ = 102.39 (2)'. The structural features of these complexes are compared to those of other related compounds and to the active sites of the copper proteins. The biological relevance of the monooxygenase model system is ...
Journal of The American Chemical Society, 1987
J. A m . Chem. SOC. and the macrocycle is C(16)-C(b4) = 3.846 ( 5 ) %.; all other distances are l... more J. A m . Chem. SOC. and the macrocycle is C(16)-C(b4) = 3.846 ( 5 ) %.; all other distances are larger. Thus the bridging alkyl chains of isomers I1 and I11 are not expected to interfere significantly with the binding of axial ligands, although they may interfere with free rotation of bound axial ligands about the M-L bond. Preliminary N M R investigations of low-spin Fe(II1) complexes of hexyl I1 and
Journal of The American Chemical Society, 1984
... Dioxygen Binding to a Structurally Characterized Phenoxide-Bridged Copper( I) Complex Kenneth... more ... Dioxygen Binding to a Structurally Characterized Phenoxide-Bridged Copper( I) Complex Kenneth D. Karlin,* Richard W. Cruse, Yilma Gultneh, Jon C. Hayes, and Jon Zubieta Department of Chemistry Slate University of ... (7) Blackburn, NJ; Karlin, K. D.; Concannon, M.; Hayes, J ...
Journal of The American Chemical Society, 1985
... Reversible O2 and CO Binding by a New Series of Binuclear Copper(1) Complexes Kenneth D. Karl... more ... Reversible O2 and CO Binding by a New Series of Binuclear Copper(1) Complexes Kenneth D. Karlin,* Michael S. Haka, Richard W. Cruse, and Yilma Gultneh Department of Chemistry, State University of New York (SUNY ... 5) Blackburn, N. J.; Karlin, K. D.; Concannon, M.; Hayes ...
Journal of The American Chemical Society, 1982
Inorganica Chimica Acta, 1983
... of a Model Copper Monooxy-genase Reaction KENNETH D. KARLIN*, JON C. HAYES, RICHARD W. CRUSE,... more ... of a Model Copper Monooxy-genase Reaction KENNETH D. KARLIN*, JON C. HAYES, RICHARD W. CRUSE, YILMA GULTNEH, JOHN P ... N3 Models for Hemocyanin THOMAS N. SORRELL*, DONALD L. JAMESON, MITCH-ELL R. MALACHOWSKI and ANDREW S. BOROVIK ...
Inorganic Chemistry, 1992
The dinucleating phenol ligand LOH (LOH = 2,6-bis((bis(2-(2-pyridyl)ethyl)amino)methyl)phenol(l))... more The dinucleating phenol ligand LOH (LOH = 2,6-bis((bis(2-(2-pyridyl)ethyl)amino)methyl)phenol(l)) is reacted with Mn(C104)y6H20 in the presence of excess acetate anion and a base (NEt3) in methanol to produce the dinuclear Mn112 complex [Mn2(LO)(OAc)z]C104 (5) which crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 11.227 (3) A, b = 21.815 (8) A, c = 17.731 (7) A, a = 90.00 (3)O, B = 102.45 (3)O, and y = 90.00 (3)O, with four molecules per unit cell. The structure shows that two acetate anions and a phenoxy oxygen bridge the manganese ions. The [Mn2(LO)(p-OAc)2]+ cation has a noncrystallographic Cz axis with the two Mn(I1)
Inorganic Chemistry, 1985
Spectra were recorded with a Nicolet NT-200 WB spectrometer, as previously d e s~r i b e d . '~, ... more Spectra were recorded with a Nicolet NT-200 WB spectrometer, as previously d e s~r i b e d . '~, '~ Results and Discussion. The ,H N M R spectra for cis-and . Carboxyl coordination of nicotinate-2-d gives rise to a distinctly narrower resonance centered at ca. +9 ppm ( summarizes the electronic spectra of cis-and trans-H[Cr(mal),(nic-N),], bands V and IV, respectively. The ligand field spectra are consistent with a Cr(N2-04) formulation by comparison with the previously characterized Cr(N,-0,) complexes listed in . The striking similarity of band maxima and molar absorptivities for band IV and previously characterized tran~-Li[Cr(mal)~(py),] l 3 is the basis for the assignment of band IV as ~rans-H[Cr(mal)~(nic-N)~]. Therefore, since band V is also a bis(ma1onato) bis(nicotinic acid) complex, it must be assigned the cis configuration as this is the only other geometrical isomer possible. The larger molar absorptivities for the d-d transitions of this isomer are consistent with the cis assignment, due to the lower symmetry associated with the cis relative to the trans configuration. The geometrical assignments could be made directly from ,H N M R spectra for the complexes with deuteriumlabeled malonate,13 but so far we have not succeeded in obtaining the desired spectra. Deuteration of the coordinated malonates was carried out as described previously for tran~-Li[Cr(mal)~-(py),]13 and was confirmed by IR spectroscopy. Apparently, the malonate protons (deuterons) undergo facile exchange in solution. This may be due to intramolecular general-base catalysis promoted by the pyridyl carboxyl group, since this facile exchange is not observed in trans-Li[Cr(mal)2(py)z], which was assigned the trans configuration by malonate ,H N M R studies.13
Acta Crystallographica Section E-structure Reports Online, 2009
Key indicators: single-crystal X-ray study; T = 200 K; mean (C-C) = 0.006 Å; R factor = 0.078; wR... more Key indicators: single-crystal X-ray study; T = 200 K; mean (C-C) = 0.006 Å; R factor = 0.078; wR factor = 0.199; data-to-parameter ratio = 31.4.
Inorganica Chimica Acta, 2006
The synthesis, structure and characterization of the dinuclear Mn(II) complex [Mn 2 (LO)(l-OAc) 2... more The synthesis, structure and characterization of the dinuclear Mn(II) complex [Mn 2 (LO)(l-OAc) 2 ](ClO 4 ) (1) where LOH = 2,6-bis-{bis(2-(2-pyridyl)ethyl)aminomethyl)}-4-methylphenol are reported. The reaction of Mn(ClO 4 ) 2 AE 6H 2 O with the dinucleating ligand LOH and H 3 CCOONa in the presence of NEt 3 in dry, degassed methanol and under an argon atmosphere, yields 1 as a colorless powder. The crystal structure of 1, determined by X-ray diffraction methods, shows a dinuclear Mn(II) complex in which two Mn(II) ions, each in six-coordinate approximate octahedral coordination, are bridged by the phenolate oxygen of LO À and by two acetate ions in a syn,syn-1,3-bridging mode. The Mn-Mn distance is 3.557(1) Å and Mn-O phenolate -Mn angle is 112.50(9)°. Cyclic voltammetry of 1 in acetonitrile solution shows a quasi-reversible wave at E 1/2 = 0.65 V, for the Mn 2 (II,II)/Mn 2 (II,III) redox process, and an irreversible oxidation peak at E p,c = 1.22 V versus Ag/AgCl for the Mn 2 (II,III) to Mn 2 (III,III) oxidation process. Controlled potential electrolysis of 1 in acetonitrile solution at 0.85 V (versus Ag/AgCl) takes up 1 F of charge per mole of 1 to yield a brown solution of the Mn 2 (II,III) state of the complex, which, however, is unstable and reverts back to the Mn 2 (II,II) state in solution at room temperature. Least square fitting of the variable temperature magnetic susceptibility measurements on powdered sample of 1 is obtained with g = 1.888, J = À2.75 cm À1 , Par = 0.008, TIP = 0. The low ÀJ value and the room temperature calculated magnetic moment of the complex (5.30 BM per Mn(II)), which is less than the spin-only moment of Mn(II), show that the two Mn(II) ions are weakly antiferromagnetically coupled.