Publications (35) View all
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Article: An ab Initio Investigation of Lithium Ion Hydration
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ABSTRACT: The structures, frequencies, and interaction energies of small lithium−water clusters, Li(H2O)n+, n = 1−4, were calculated by ab initio Hartree−Fock theory with small- and medium-sized basis sets (STO-3G, 3-21G, 6-31G*, 6-31G**, 6-31+G*, 6-31+G*(5d), 6-311G*). The interaction energies were corrected for basis set superposition error (BSSE) by Mayer's CHA/CE formalism. The CHA/CE/6-31+G*//HF/6-31+G* level gives an excellent description of the binding energy. The geometry and symmetric stretch frequency for Li(H2O)4+ of 248 cm-1 (255 cm-1 expt) are well described at the HF/6-31G* level. The choice of partition of the supermolecule was demonstrated to be of minor importance (±4 kJ/mol). The binding energies were rationalized on crowding around the ion and a weakening Li−O interaction. The first ab initio calculation (STO-3G, 3-21G, 6-31G*, 6-31+G*) of a full second-solvation sphere of a metal cation is presented ([Li(H2O)4+](H2O)n, n = 4,8). The second solvation sphere of four waters raises the frequency of the Li−O vibration by 18 cm-1 (7%).The Journal of Physical Chemistry 02/2013; 100(2):601-605. -
Article: An ab Initio and Raman Investigation of Sulfate Ion Hydration
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ABSTRACT: The Raman spectra of ammonium sulfate solution are measured. The geometries, energies, and vibrational frequencies of various isomers of SO42- (H2O)n, n = 0−6 are calculated at various levels up to MP2/6-31+G*. These properties are studied as a function of increasing cluster size. The experimental and theoretical vibrational spectra are compared.The Journal of Physical Chemistry A 02/2013; 105(5):905-912. · 2.95 Impact Factor -
Article: An ab Initio, Infrared, and Raman Investigation of Phosphate Ion Hydration
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ABSTRACT: The low-frequency infrared and Raman spectra of sodium and potassium phosphate solutions have been measured and discussed. The geometries, energies, and vibrational frequencies of various isomers of PO43-(H2O) n, n = 0−6 are calculated at various levels up to MP2/6-31+G*. These properties are studied as a function of increasing cluster size. The experimental and theoretical vibrational spectra are compared.The Journal of Physical Chemistry A 02/2013; 107:8746-8755. · 2.95 Impact Factor -
Article: Preparation of a Diphosphine with Persistent Phosphinyl Radical Character in Solution: Characterization, Reactivity with O(2), S(8), Se, Te, and P(4), and Electronic Structure Calculations.
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ABSTRACT: A new, easily synthesized diphosphine based on a heterocyclic 1,3,2-diazaphospholidine framework has been prepared. Due to the large, sterically encumbering Dipp groups (Dipp = 2,6-diisopropylphenyl) on the heterocyclic ring, the diphosphine undergoes homolytic cleavage of the P-P bond in solution to form two phosphinyl radicals. The diphosphine has been reacted with O(2), S(8), Se, Te, and P(4), giving products that involve insertion of elements between the P-P bond to yield the related phosphinic acid anhydride, sulfide/disulfide, selenide, telluride, and a butterfly-type perphospha-bicyclobutadiene structure with a trans,trans-geometry. All molecules have been characterized by multinuclear NMR spectroscopy, elemental analysis, and single-crystal X-ray crystallography. Variable-temperature EPR spectroscopy was utilized to study the nature of the phosphinyl radical in solution. Electronic structure calculations were performed on a number of systems from the parent diphosphine [H(2)P](2) to amino-substituted [(H(2)N)(2)P](2) and cyclic amino-substituted [(H(2)C)(2)(NH)(2)P](2); then, bulky substituents (Ph or Dipp) were attached to the cyclic amino systems. Calculations on the isolated diphosphine at the B3LYP/6-31+G* level show that the homolytic cleavage of the P-P bond to form two phosphinyl radicals is favored over the diphosphine by ∼11 kJ/mol. Furthermore, there is a significant amount of relaxation energy stored in the ligands (52.3 kJ/mol), providing a major driving force behind the homolytic cleavage of the central P-P bond.Inorganic Chemistry 10/2012; · 4.60 Impact Factor -
Article: Lewis base stabilized oxophosphonium ions.
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ABSTRACT: Totally OXOme! Monomeric oxophosphonium ions have been prepared from N-heterocyclic phosphenium ions and triethylamine or pyridine N-oxides (see picture; Dipp=2,6-diisopropylphenyl). Their structures were confirmed by single-crystal X-ray crystallography.Angewandte Chemie International Edition 09/2012; 51(43):10836-40. · 13.45 Impact Factor
