Abstract: The new osmium (VII1) oxo fluoride obtained from the reaction of KrF2 and Os04 in anhyd... more Abstract: The new osmium (VII1) oxo fluoride obtained from the reaction of KrF2 and Os04 in anhydrous HF solution and originally identifed as OsOF6 is shown by quantitative material balance, electron diffraction, NMR and vibrational spectroscopy, and density functional ...
The hydrolysis and carbonate complexation of the alkaline earth cations Ca2+and Sr2+were investig... more The hydrolysis and carbonate complexation of the alkaline earth cations Ca2+and Sr2+were investigated by using a combined experimental and modeling approach. The modeling approach uses both macroscopic thermodynamic models and molecular modeling at the density functional theory (DFT) level. The molecular modeling calculations identify possible speciation schemes in the thermodynamic modeling and provide molecular level insight into the macroscopically observed
Density functional theory (DFT) and coupled cluster theory (CCSD(T)) were used to study the addit... more Density functional theory (DFT) and coupled cluster theory (CCSD(T)) were used to study the addition of CO2 to group 4 (MO2)n and group 6 (MO3)n (n = 1, 2, 3) nanoclusters. The structures and energetics arising from Lewis acid-base addition (physisorption) and formation of CO3(2-) (chemisorption) of CO2 to these clusters were predicted. Physisorption and chemisorption of CO2 are predicted to be thermodynamically allowed for group 4 (MO2)n clusters, with chemisorption being more favored energetically. Correlations of the ligand binding energies (LBEs) for the group 4 clusters are made with the fluoride affinities and M-O and M═O bond strengths of the clusters. The LBEs for chemisorption on the Zr and Ti clusters are consistent with published experimental and computational studies of bulk solids. Physisorption LBEs for the Ti and Zr clusters are more exothermic than the bulk values, as the cluster models allow for better relaxation at the metal sites. Chemisorption is not predicted to...
Dalton transactions (Cambridge, England : 2003), Jan 20, 2016
Niobium oxotriazide, [NbO(N3)3], was prepared in a fluoride-azide exchange reaction between [NbOF... more Niobium oxotriazide, [NbO(N3)3], was prepared in a fluoride-azide exchange reaction between [NbOF3] and an excess of Me3SiN3 in SO2 solution. In acetonitrile solution, the fluoride-azide exchange resulted in the isolation of the adduct [NbO(N3)3·2CH3CN]. The subsequent reaction of [NbO(N3)3] with 2,2'-bipyridine (bipy) resulted in the isolation of the bipyridine adduct [(bipy)NbO(N3)3]. The pentaazido anion [NbO(N3)5](2-) was obtained by the reaction of [NbO(N3)3] with two equivalents of ionic azide. The novel niobium oxoazides were fully characterized by their vibrational spectra, impact, friction and thermal sensitivity data and, in the case of [(bipy)NbO(N3)3], Cs2[NbO(N3)5], and [PPh4]2[NbO2(N3)5] by their X-ray crystal structures.
Journal of the American Chemical Society, Jan 16, 2015
Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by ele... more Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by elemental analysis, multinuclear NMR spectroscopy, X-ray crystallography, and powder X-ray diffraction. The remarkable cobalt fluoride (19)F NMR chemical shifts (-716 to -759 ppm) were studied computationally, and the contributing paramagnetic and diamagnetic factors were extracted. Additionally, the complexes were shown to be active in the catalytic fluorination of p-toluoyl chloride. Furthermore, two examples of cobalt(III) bis(perfluoroalkyl)complexes were synthesized and their reactivity studied. Interestingly, abstraction of a fluoride ion from these complexes led to selective formation of cobalt difluorocarbene complexes derived from the trifluoromethyl ligand. These electrophilic difluorocarbenes were shown to undergo insertion into the remaining perfluoroalkyl fragment, demonstrating the elongation of a perfluoroalkyl chain arising from a difluorocarbene insertion on a cobalt metal ...
A break in periodicity occurs in the actinide series between plutonium and americium as the resul... more A break in periodicity occurs in the actinide series between plutonium and americium as the result of the localization of 5f electrons. The subsequent chemistry of later actinides is thought to closely parallel lanthanides in that bonding is expected to be ionic and complexation should not substantially alter the electronic structure of the metal ions. Here we demonstrate that ligation of californium(III) by a pyridine derivative results in significant deviations in the properties of the resultant complex with respect to that predicted for the free ion. We expand on this by characterizing the americium and curium analogues for comparison, and show that these pronounced effects result from a second transition in periodicity in the actinide series that occurs, in part, because of the stabilization of the divalent oxidation state. The metastability of californium(II) is responsible for many of the unusual properties of californium including the green photoluminescence.
The journal of physical chemistry. A, Jan 26, 2015
Aqueous metal ions play an important role in many areas of chemistry. The acidities of [Be(H2O)4]... more Aqueous metal ions play an important role in many areas of chemistry. The acidities of [Be(H2O)4](2+), [M(H2O)6](2+), M = Mg(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), and Hg(2+), and [M(H2O)n](2+), M = Ca(2+) and Sr(2+), n = 7 and 8, complexes have been predicted using density functional theory, second-order Møller-Plesset perturbation theory (MP2), and coupled cluster CCSD(T) theory in the gas phase. pKa's in aqueous solution were predicted by using self-consistent reaction field (SCRF) calculations with different solvation models. The most common binding motif of the majority of the metal +2 complexes is coordination number (CN) 6, with each hexaaquo cluster having reasonably high symmetry for the best arrangement of the water molecules in the first solvation shell. Be(2+) is tetracoordinated, but a second solvation shell of 8 waters is needed to predict the pKa. The Ca(2+) and Sr(2+) aquo clusters have a coordination number of 7 or 8 as found in terms of th...
Chemical communications (Cambridge, England), Jan 4, 2015
Reactions of laser-ablated U atoms with (CN)2 produce UNC, U(NC)2, and U(NC)4 as the major produc... more Reactions of laser-ablated U atoms with (CN)2 produce UNC, U(NC)2, and U(NC)4 as the major products, identified from their Ar matrix infrared spectra and precursors partially and fully substituted with (13)C and (15)N. Mixed isotopic multiplets substantiate product stoichiometries. Band positions and quantum chemical calculations verify the isocyanide bonding.
Abstract: The new osmium (VII1) oxo fluoride obtained from the reaction of KrF2 and Os04 in anhyd... more Abstract: The new osmium (VII1) oxo fluoride obtained from the reaction of KrF2 and Os04 in anhydrous HF solution and originally identifed as OsOF6 is shown by quantitative material balance, electron diffraction, NMR and vibrational spectroscopy, and density functional ...
The hydrolysis and carbonate complexation of the alkaline earth cations Ca2+and Sr2+were investig... more The hydrolysis and carbonate complexation of the alkaline earth cations Ca2+and Sr2+were investigated by using a combined experimental and modeling approach. The modeling approach uses both macroscopic thermodynamic models and molecular modeling at the density functional theory (DFT) level. The molecular modeling calculations identify possible speciation schemes in the thermodynamic modeling and provide molecular level insight into the macroscopically observed
Density functional theory (DFT) and coupled cluster theory (CCSD(T)) were used to study the addit... more Density functional theory (DFT) and coupled cluster theory (CCSD(T)) were used to study the addition of CO2 to group 4 (MO2)n and group 6 (MO3)n (n = 1, 2, 3) nanoclusters. The structures and energetics arising from Lewis acid-base addition (physisorption) and formation of CO3(2-) (chemisorption) of CO2 to these clusters were predicted. Physisorption and chemisorption of CO2 are predicted to be thermodynamically allowed for group 4 (MO2)n clusters, with chemisorption being more favored energetically. Correlations of the ligand binding energies (LBEs) for the group 4 clusters are made with the fluoride affinities and M-O and M═O bond strengths of the clusters. The LBEs for chemisorption on the Zr and Ti clusters are consistent with published experimental and computational studies of bulk solids. Physisorption LBEs for the Ti and Zr clusters are more exothermic than the bulk values, as the cluster models allow for better relaxation at the metal sites. Chemisorption is not predicted to...
Dalton transactions (Cambridge, England : 2003), Jan 20, 2016
Niobium oxotriazide, [NbO(N3)3], was prepared in a fluoride-azide exchange reaction between [NbOF... more Niobium oxotriazide, [NbO(N3)3], was prepared in a fluoride-azide exchange reaction between [NbOF3] and an excess of Me3SiN3 in SO2 solution. In acetonitrile solution, the fluoride-azide exchange resulted in the isolation of the adduct [NbO(N3)3·2CH3CN]. The subsequent reaction of [NbO(N3)3] with 2,2'-bipyridine (bipy) resulted in the isolation of the bipyridine adduct [(bipy)NbO(N3)3]. The pentaazido anion [NbO(N3)5](2-) was obtained by the reaction of [NbO(N3)3] with two equivalents of ionic azide. The novel niobium oxoazides were fully characterized by their vibrational spectra, impact, friction and thermal sensitivity data and, in the case of [(bipy)NbO(N3)3], Cs2[NbO(N3)5], and [PPh4]2[NbO2(N3)5] by their X-ray crystal structures.
Journal of the American Chemical Society, Jan 16, 2015
Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by ele... more Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by elemental analysis, multinuclear NMR spectroscopy, X-ray crystallography, and powder X-ray diffraction. The remarkable cobalt fluoride (19)F NMR chemical shifts (-716 to -759 ppm) were studied computationally, and the contributing paramagnetic and diamagnetic factors were extracted. Additionally, the complexes were shown to be active in the catalytic fluorination of p-toluoyl chloride. Furthermore, two examples of cobalt(III) bis(perfluoroalkyl)complexes were synthesized and their reactivity studied. Interestingly, abstraction of a fluoride ion from these complexes led to selective formation of cobalt difluorocarbene complexes derived from the trifluoromethyl ligand. These electrophilic difluorocarbenes were shown to undergo insertion into the remaining perfluoroalkyl fragment, demonstrating the elongation of a perfluoroalkyl chain arising from a difluorocarbene insertion on a cobalt metal ...
A break in periodicity occurs in the actinide series between plutonium and americium as the resul... more A break in periodicity occurs in the actinide series between plutonium and americium as the result of the localization of 5f electrons. The subsequent chemistry of later actinides is thought to closely parallel lanthanides in that bonding is expected to be ionic and complexation should not substantially alter the electronic structure of the metal ions. Here we demonstrate that ligation of californium(III) by a pyridine derivative results in significant deviations in the properties of the resultant complex with respect to that predicted for the free ion. We expand on this by characterizing the americium and curium analogues for comparison, and show that these pronounced effects result from a second transition in periodicity in the actinide series that occurs, in part, because of the stabilization of the divalent oxidation state. The metastability of californium(II) is responsible for many of the unusual properties of californium including the green photoluminescence.
The journal of physical chemistry. A, Jan 26, 2015
Aqueous metal ions play an important role in many areas of chemistry. The acidities of [Be(H2O)4]... more Aqueous metal ions play an important role in many areas of chemistry. The acidities of [Be(H2O)4](2+), [M(H2O)6](2+), M = Mg(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), and Hg(2+), and [M(H2O)n](2+), M = Ca(2+) and Sr(2+), n = 7 and 8, complexes have been predicted using density functional theory, second-order Møller-Plesset perturbation theory (MP2), and coupled cluster CCSD(T) theory in the gas phase. pKa's in aqueous solution were predicted by using self-consistent reaction field (SCRF) calculations with different solvation models. The most common binding motif of the majority of the metal +2 complexes is coordination number (CN) 6, with each hexaaquo cluster having reasonably high symmetry for the best arrangement of the water molecules in the first solvation shell. Be(2+) is tetracoordinated, but a second solvation shell of 8 waters is needed to predict the pKa. The Ca(2+) and Sr(2+) aquo clusters have a coordination number of 7 or 8 as found in terms of th...
Chemical communications (Cambridge, England), Jan 4, 2015
Reactions of laser-ablated U atoms with (CN)2 produce UNC, U(NC)2, and U(NC)4 as the major produc... more Reactions of laser-ablated U atoms with (CN)2 produce UNC, U(NC)2, and U(NC)4 as the major products, identified from their Ar matrix infrared spectra and precursors partially and fully substituted with (13)C and (15)N. Mixed isotopic multiplets substantiate product stoichiometries. Band positions and quantum chemical calculations verify the isocyanide bonding.
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