Morrin Aoife and Moutloali Richard M and Killard Anthony J and Smyth Malcolm R and Darkwa James and Iwuoha Emmanuel I Electrocatalytic Sensor Devices Cyclopentadienylnickel Thiolato Schiff Base Monolayer Self Assembled on Gold Talanta 64 Pp 30 38 Issn 0039 9140, May 19, 2004
Journal of the Chemical Society Faraday Transactions, 1996
The oxidation of hydroxymethanesulfinic acid, HMSA, by acidic iodate has been studied by spectrop... more The oxidation of hydroxymethanesulfinic acid, HMSA, by acidic iodate has been studied by spectrophotometric techniques. The reaction presents clock reaction characteristics in which in excess iodate conditions there is an initial quiescent period that is followed by a rapid ...
A series of homochalcogenide and mixed-chalcogenide ligand complexes of palladium and platinum ha... more A series of homochalcogenide and mixed-chalcogenide ligand complexes of palladium and platinum have been prepared from the reactions of Pd(dppf)Cl2, (dppf=1,1′-bis(diphenylphosphino)ferrocene), Pd(dippf)Cl2 (1,1′-bis(diisopropylphosphino)ferrocene), and Pt(dppf)Cl2 with 1,2-benzenedithiol (HSC6H4SH) (a), 3,4-toluenedithiol (HSC6H3MeSH) (b), 3,6-dichloro-1,2-benzenedithiol (HSC6H2Cl2SH) (c), 2-mercaptophenol (HSC6H4OH) (d), thiosalicylic acid (HSC6H4CO2H) (e) and thionicotinic acid (HSC6H3NCO2H) (f). Single-crystal X-ray diffraction studies show that all complexes have distorted square-planar geometry. The complexes undergo two quasi-reversible or irreversible one-electron redox processes that involve the chalcogen ligands and diphosphinoferrocene ligands. The oxidation potentials of the chalcogen ligands increase when they bear electron-withdrawing substituents.Reaction of ferrocene anchored diphosphino palladium and platinum dichlorides with various dithiols provide a simple route to palladium and platinum thiolato complexes. Single-crystal X-ray structural analysis show that the complexes have square planar geometry. Electrochemistry of the complexes shows the effect of thiolato ligand substituents on the ease of oxidation of these complexes.
Acta Crystallographica Section E Structure Reports Online
In the title compound, [PdCl2(C5H8N2)(C12H12N2O)], the Pd atom adopts a slightly distorted trans-... more In the title compound, [PdCl2(C5H8N2)(C12H12N2O)], the Pd atom adopts a slightly distorted trans-PdCl2N2 square-planar arrangement. The different Pd—N bond lengths can be related to the the electron-withdrawing effect of the o-toluoyl group on the substituted pyrazole ligand. The complex crystallizes as centrosymmetric hydrogen-bonded dimers through N—H...Cl linkages.
ABSTRACT The reaction of Zn(OAc)2 with 3-ferrocenylpyrazol-1-ylmethylenepyridine (L1), 3-ferrocen... more ABSTRACT The reaction of Zn(OAc)2 with 3-ferrocenylpyrazol-1-ylmethylenepyridine (L1), 3-ferrocenyl-5-methylpyrazol-1-ylmethylenepyridine (L2), 3-ferrocenylpyrazol-1-ylethylamine (L3) and 3-ferrocenyl-5-pyrazol-1-ylethylamine (L4) afford the corresponding zinc complexes [Zn(CH3COO)2(L1)] (1), [Zn(CH3COO)2(L2)] (2), [Zn(CH3COO)2(L3)] (3), and [Zn(CH3COO)2(L4)] (4). These zinc complexes behave as catalysts or initiators for the ring opening polymerization of ϵ-caprolactone, depending on the nature of the ligands, to produce polymers that are capped with α,ω-dihydroxy, hydroxyl or ferrocenylpyrazolylethylamino end groups. Complexes 1 and 2 were found to act as catalysts when the [CL]/[C] ratios were varied from 100 to 800 to produce PCL with α,ω-dihydroxy and nearly the same molecular weight. Complexes 3 and 4 on the other hand act as initiators to produce a mixture of PCL that have polymers with ferrocenylpyrazolylethylamino and a hydroxyl as end groups as the major component of the mixture and minor species with α,ω-dihydroxy end group.
The title compound, [PdBr(C(14)H(21)S(2))] or [PdBr[C(6)H(3)(CH(2)S(i)Pr)(2)-2,6]], exhibits squa... more The title compound, [PdBr(C(14)H(21)S(2))] or [PdBr[C(6)H(3)(CH(2)S(i)Pr)(2)-2,6]], exhibits square-planar geometry at the Pd centre, with three atoms of the square plane provided by the rigid thiopincer ligand, i.e. 1,3-bis(thiomethyl)benzene.
The palladium(II) center in the title compound, trans-[PdCl2(C5H2F6N2)2].H2O, possesses a distort... more The palladium(II) center in the title compound, trans-[PdCl2(C5H2F6N2)2].H2O, possesses a distorted square-planar geometry. The NH groups are positioned on the same side of the PdN2Cl2 coordination plane. Four symmetry-independent strong hydrogen bonds of three types (N-H...Cl, N-H...Cl and O-H...Cl) hold the structure together.
The title compound {2-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-ylmethyl]-6-(3,5-dimethyl-1H-pyrazol... more The title compound {2-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-ylmethyl]-6-(3,5-dimethyl-1H-pyrazol-1-ylmethyl)pyridine}methylpalladium(II) tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [Pd(C(18)H(18)F(6)N(5))][B(C(8)H(3)F(6))(4)], crystallizes as discrete cations and anions. The cation possesses a pseudo-twofold axis about which positional disorder of the tridentate ligand is exhibited. The four substituents on the two pyrazole rings exhibit CH(3)/CF(3) disorder, while all other atoms are ordered. Thus, this disorder can be conveniently described 'locally' as compositional, while 'globally' for the entire tridentate ligand it is positional. The anion also exhibits typical rotational positional disorder in three of the CF(3) groups. All disordered CF(3) groups were modeled with idealized C(3v) geometry.
The title compound, [CoCl(2)(C(11)H(20)ClN(2))(2)], forms two intramolecular hydrogen bonds [grap... more The title compound, [CoCl(2)(C(11)H(20)ClN(2))(2)], forms two intramolecular hydrogen bonds [graph set S(5)] between the N atoms of the pyrazole ligands and the chloride ligands. This hydrogen-bonding motif is uncommon among related compounds but occurs here because of the bulk of tert-butyl substituents on the pyrazole ligands which shield the central metal atom to a significantly larger extent than pyrazole ligands with smaller 3,5-substituents.
Morrin Aoife and Moutloali Richard M and Killard Anthony J and Smyth Malcolm R and Darkwa James and Iwuoha Emmanuel I Electrocatalytic Sensor Devices Cyclopentadienylnickel Thiolato Schiff Base Monolayer Self Assembled on Gold Talanta 64 Pp 30 38 Issn 0039 9140, May 19, 2004
Journal of the Chemical Society Faraday Transactions, 1996
The oxidation of hydroxymethanesulfinic acid, HMSA, by acidic iodate has been studied by spectrop... more The oxidation of hydroxymethanesulfinic acid, HMSA, by acidic iodate has been studied by spectrophotometric techniques. The reaction presents clock reaction characteristics in which in excess iodate conditions there is an initial quiescent period that is followed by a rapid ...
A series of homochalcogenide and mixed-chalcogenide ligand complexes of palladium and platinum ha... more A series of homochalcogenide and mixed-chalcogenide ligand complexes of palladium and platinum have been prepared from the reactions of Pd(dppf)Cl2, (dppf=1,1′-bis(diphenylphosphino)ferrocene), Pd(dippf)Cl2 (1,1′-bis(diisopropylphosphino)ferrocene), and Pt(dppf)Cl2 with 1,2-benzenedithiol (HSC6H4SH) (a), 3,4-toluenedithiol (HSC6H3MeSH) (b), 3,6-dichloro-1,2-benzenedithiol (HSC6H2Cl2SH) (c), 2-mercaptophenol (HSC6H4OH) (d), thiosalicylic acid (HSC6H4CO2H) (e) and thionicotinic acid (HSC6H3NCO2H) (f). Single-crystal X-ray diffraction studies show that all complexes have distorted square-planar geometry. The complexes undergo two quasi-reversible or irreversible one-electron redox processes that involve the chalcogen ligands and diphosphinoferrocene ligands. The oxidation potentials of the chalcogen ligands increase when they bear electron-withdrawing substituents.Reaction of ferrocene anchored diphosphino palladium and platinum dichlorides with various dithiols provide a simple route to palladium and platinum thiolato complexes. Single-crystal X-ray structural analysis show that the complexes have square planar geometry. Electrochemistry of the complexes shows the effect of thiolato ligand substituents on the ease of oxidation of these complexes.
Acta Crystallographica Section E Structure Reports Online
In the title compound, [PdCl2(C5H8N2)(C12H12N2O)], the Pd atom adopts a slightly distorted trans-... more In the title compound, [PdCl2(C5H8N2)(C12H12N2O)], the Pd atom adopts a slightly distorted trans-PdCl2N2 square-planar arrangement. The different Pd—N bond lengths can be related to the the electron-withdrawing effect of the o-toluoyl group on the substituted pyrazole ligand. The complex crystallizes as centrosymmetric hydrogen-bonded dimers through N—H...Cl linkages.
ABSTRACT The reaction of Zn(OAc)2 with 3-ferrocenylpyrazol-1-ylmethylenepyridine (L1), 3-ferrocen... more ABSTRACT The reaction of Zn(OAc)2 with 3-ferrocenylpyrazol-1-ylmethylenepyridine (L1), 3-ferrocenyl-5-methylpyrazol-1-ylmethylenepyridine (L2), 3-ferrocenylpyrazol-1-ylethylamine (L3) and 3-ferrocenyl-5-pyrazol-1-ylethylamine (L4) afford the corresponding zinc complexes [Zn(CH3COO)2(L1)] (1), [Zn(CH3COO)2(L2)] (2), [Zn(CH3COO)2(L3)] (3), and [Zn(CH3COO)2(L4)] (4). These zinc complexes behave as catalysts or initiators for the ring opening polymerization of ϵ-caprolactone, depending on the nature of the ligands, to produce polymers that are capped with α,ω-dihydroxy, hydroxyl or ferrocenylpyrazolylethylamino end groups. Complexes 1 and 2 were found to act as catalysts when the [CL]/[C] ratios were varied from 100 to 800 to produce PCL with α,ω-dihydroxy and nearly the same molecular weight. Complexes 3 and 4 on the other hand act as initiators to produce a mixture of PCL that have polymers with ferrocenylpyrazolylethylamino and a hydroxyl as end groups as the major component of the mixture and minor species with α,ω-dihydroxy end group.
The title compound, [PdBr(C(14)H(21)S(2))] or [PdBr[C(6)H(3)(CH(2)S(i)Pr)(2)-2,6]], exhibits squa... more The title compound, [PdBr(C(14)H(21)S(2))] or [PdBr[C(6)H(3)(CH(2)S(i)Pr)(2)-2,6]], exhibits square-planar geometry at the Pd centre, with three atoms of the square plane provided by the rigid thiopincer ligand, i.e. 1,3-bis(thiomethyl)benzene.
The palladium(II) center in the title compound, trans-[PdCl2(C5H2F6N2)2].H2O, possesses a distort... more The palladium(II) center in the title compound, trans-[PdCl2(C5H2F6N2)2].H2O, possesses a distorted square-planar geometry. The NH groups are positioned on the same side of the PdN2Cl2 coordination plane. Four symmetry-independent strong hydrogen bonds of three types (N-H...Cl, N-H...Cl and O-H...Cl) hold the structure together.
The title compound {2-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-ylmethyl]-6-(3,5-dimethyl-1H-pyrazol... more The title compound {2-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-ylmethyl]-6-(3,5-dimethyl-1H-pyrazol-1-ylmethyl)pyridine}methylpalladium(II) tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [Pd(C(18)H(18)F(6)N(5))][B(C(8)H(3)F(6))(4)], crystallizes as discrete cations and anions. The cation possesses a pseudo-twofold axis about which positional disorder of the tridentate ligand is exhibited. The four substituents on the two pyrazole rings exhibit CH(3)/CF(3) disorder, while all other atoms are ordered. Thus, this disorder can be conveniently described 'locally' as compositional, while 'globally' for the entire tridentate ligand it is positional. The anion also exhibits typical rotational positional disorder in three of the CF(3) groups. All disordered CF(3) groups were modeled with idealized C(3v) geometry.
The title compound, [CoCl(2)(C(11)H(20)ClN(2))(2)], forms two intramolecular hydrogen bonds [grap... more The title compound, [CoCl(2)(C(11)H(20)ClN(2))(2)], forms two intramolecular hydrogen bonds [graph set S(5)] between the N atoms of the pyrazole ligands and the chloride ligands. This hydrogen-bonding motif is uncommon among related compounds but occurs here because of the bulk of tert-butyl substituents on the pyrazole ligands which shield the central metal atom to a significantly larger extent than pyrazole ligands with smaller 3,5-substituents.
Uploads
Papers by James Darkwa