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Papers by daniel padron

Research paper thumbnail of Ice Force Criteria for Bering Sea Offshore Loading Terminals

Offshore Technology Conference, 1985

Research paper thumbnail of Synthesis and Properties of New (Phosphinoylmethyl)Pyridine N-Oxides

Zeitschrift für anorganische und allgemeine Chemie, 2013

ABSTRACT Syntheses for 2-[1-(diarylphosphinoyl)-1-(pyridin-2-yl)methyl]pyridines, (8a, b), and 2-... more ABSTRACT Syntheses for 2-[1-(diarylphosphinoyl)-1-(pyridin-2-yl)methyl]pyridines, (8a, b), and 2-[1-(diarylphosphinoyl)-1, 1-bis(methylpyridin-2yl)methyl]pyridines, (11a, b), (Ar = C6H5 and 2-CF3C6H4), based on substitution of 2-methylpyridine fragments onto the exo methylene carbon atom of 2-[(diaryl)phosphinoylmethyl]pyridine platforms, are described. N-oxidations of 8a, b and 11a, b produced the 2-[1-(diarylphosphinoyl)-1-(1-oxy-pyridin-2yl)methyl]pyridine N-oxides (5a, b) and the 2-[1-(diarylphosphinoyl)-1, 1-bis(1-oxy-methylpyridin-2-yl)methyl]pyridines (6a, b), respectively. The “short-arm“ pyridine fragment of 11a, b resists N-oxidation, and the fully oxidized molecules, 2-[1-(diarylphosphinoyl)-1, 1-bis(1-oxy-methylpyridin-2-yl)methyl]pyridine N-oxides (7a, b) were not isolated. Molecular mechanics calculations for gas phase 1:1 ligand/lanthanide complexes indicated that 5a should accommodate a tridentate NO(meNO)PO coordination mode with minimal steric strain. In contrast, 7a cannot form tetradentate NO(meNO)2PO chelates; however, tridentate binding should be accessible with minimal ligand strain. Coordination complexes of 8a, b, 5a, b, 6a, b and 11a, b with Ln(NO3)3 salts were isolated and a X-ray crystal structure for [Er(8a)(NO3)3(MeOH)2]·CH2Cl2, revealed a monodentate Er–O=P interaction. On the other hand, complexes formed by a more symmetrical trifunctional phenylphosphino-bis-2-methylpyridine N, N, P-trioxide ligand, (meNO)2PO*, {La[(meNO)2PO*)](OTf)2(MeOH)3(H2O)+}(OTf–) and {Pr[(meNO)2PO*)](OTf)(MeOH)4+}(OTf–)2, realized a tridentate coordination mode. Solvent extraction behaviors for EuIII and AmIII in nitric acid solutions using 5a, b, 6a, b, Ph3PO and the parent bifunctional ligand 2-[(diphenylphosphanyl)methyl]pyridine N, P-dioxide (3a) in 1, 2-dichloroethane were assessed, and 5a, b and 6a, b were found to behave more like Ph3PO than 3a.

Research paper thumbnail of Syntheses and coordination studies of 2-(diphenylphosphinomethyl)pyridine and its oxide towards mercury(II)

Research paper thumbnail of Syntheses and coordination studies of 2-(diphenylphosphinomethyl)pyridine N,P dioxide with Co2+, Ni2+, Cu2+ and Zn2+ tetrafluoroborate

Inorganica Chimica Acta, 2013

Several new coordination complexes of Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ were synthesized by the rea... more Several new coordination complexes of Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ were synthesized by the reaction of their corresponding tetrafluoroborate salts with 2-(diphenylphosphinomethyl)pyridine N,P dioxide, L. All structures were determined by single-crystal X-ray crystallography showing an octahedral environment around the metal centers. Single crystals of M(BF 4 ) 2 L 2 (S) 2 (M = Co 2+ , Ni 2+ or Zn 2+ ; S = MeOH or CH 3 CN) were obtained at À5°C by slow diffusion of ether into solutions of these complexes. When these crystals were re-dissolved in methanol and allowed to grow again at room temperature using the same technique and solvent system, the product obtained presented a 3:1 ratio ligand-to-metal. The complex [Cu(BF 4 ) 2-L 2 (MeOH)](BF 4 ), exhibits two units of L, one molecule of MeOH and one counter-anion coordinated to the Cu 2+ center. This can be attributed to the steric restrictions generated by the lower symmetry in this complex, a product of significant Jahn-Teller effects, which favors a long range interaction between the metal center and a less coordinative counter-anion, compared to a MeOH unit. A 1:1 ligand-to-metal ratio complex of Ni 2+ was also obtained by allowing the starting materials to react for only a short time. Attempts to obtain single crystal of complexes of Co 2+ , Cu 2+ or Zn 2+ in a 1:1 ratio were not successful. The resulting 3:1 ligand-to-metal products were fully characterized by elemental analysis, UV-Vis spectroscopy and FT-IR spectroscopy.

Research paper thumbnail of Syntheses and Coordination Studies of 2-(Phosphanylmethyl)pyridine Dioxide toward Silver (I)

European Journal of Inorganic Chemistry, 2013

The coordination properties of the 2-[(diphenylphosphanyl)methyl]pyridine N,P-dioxide ligand towa... more The coordination properties of the 2-[(diphenylphosphanyl)methyl]pyridine N,P-dioxide ligand towards three different silver(I) salts are described. The molecular structures of the coordination complexes obtained showed a strong dependence on the 2-[(diphenylphosphanyl)methyl]pyridine N,Pdioxide ligand and the binding ability of the counterion. The strongly binding trifluoroacetate ion yielded a unique planar

Research paper thumbnail of SOLICITUD -REGISTRO/AUTORIZACIÓN

Research paper thumbnail of Ice Force Criteria for Bering Sea Offshore Loading Terminals

Offshore Technology Conference, 1985

Research paper thumbnail of Synthesis and Properties of New (Phosphinoylmethyl)Pyridine N-Oxides

Zeitschrift für anorganische und allgemeine Chemie, 2013

ABSTRACT Syntheses for 2-[1-(diarylphosphinoyl)-1-(pyridin-2-yl)methyl]pyridines, (8a, b), and 2-... more ABSTRACT Syntheses for 2-[1-(diarylphosphinoyl)-1-(pyridin-2-yl)methyl]pyridines, (8a, b), and 2-[1-(diarylphosphinoyl)-1, 1-bis(methylpyridin-2yl)methyl]pyridines, (11a, b), (Ar = C6H5 and 2-CF3C6H4), based on substitution of 2-methylpyridine fragments onto the exo methylene carbon atom of 2-[(diaryl)phosphinoylmethyl]pyridine platforms, are described. N-oxidations of 8a, b and 11a, b produced the 2-[1-(diarylphosphinoyl)-1-(1-oxy-pyridin-2yl)methyl]pyridine N-oxides (5a, b) and the 2-[1-(diarylphosphinoyl)-1, 1-bis(1-oxy-methylpyridin-2-yl)methyl]pyridines (6a, b), respectively. The “short-arm“ pyridine fragment of 11a, b resists N-oxidation, and the fully oxidized molecules, 2-[1-(diarylphosphinoyl)-1, 1-bis(1-oxy-methylpyridin-2-yl)methyl]pyridine N-oxides (7a, b) were not isolated. Molecular mechanics calculations for gas phase 1:1 ligand/lanthanide complexes indicated that 5a should accommodate a tridentate NO(meNO)PO coordination mode with minimal steric strain. In contrast, 7a cannot form tetradentate NO(meNO)2PO chelates; however, tridentate binding should be accessible with minimal ligand strain. Coordination complexes of 8a, b, 5a, b, 6a, b and 11a, b with Ln(NO3)3 salts were isolated and a X-ray crystal structure for [Er(8a)(NO3)3(MeOH)2]·CH2Cl2, revealed a monodentate Er–O=P interaction. On the other hand, complexes formed by a more symmetrical trifunctional phenylphosphino-bis-2-methylpyridine N, N, P-trioxide ligand, (meNO)2PO*, {La[(meNO)2PO*)](OTf)2(MeOH)3(H2O)+}(OTf–) and {Pr[(meNO)2PO*)](OTf)(MeOH)4+}(OTf–)2, realized a tridentate coordination mode. Solvent extraction behaviors for EuIII and AmIII in nitric acid solutions using 5a, b, 6a, b, Ph3PO and the parent bifunctional ligand 2-[(diphenylphosphanyl)methyl]pyridine N, P-dioxide (3a) in 1, 2-dichloroethane were assessed, and 5a, b and 6a, b were found to behave more like Ph3PO than 3a.

Research paper thumbnail of Syntheses and coordination studies of 2-(diphenylphosphinomethyl)pyridine and its oxide towards mercury(II)

Research paper thumbnail of Syntheses and coordination studies of 2-(diphenylphosphinomethyl)pyridine N,P dioxide with Co2+, Ni2+, Cu2+ and Zn2+ tetrafluoroborate

Inorganica Chimica Acta, 2013

Several new coordination complexes of Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ were synthesized by the rea... more Several new coordination complexes of Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ were synthesized by the reaction of their corresponding tetrafluoroborate salts with 2-(diphenylphosphinomethyl)pyridine N,P dioxide, L. All structures were determined by single-crystal X-ray crystallography showing an octahedral environment around the metal centers. Single crystals of M(BF 4 ) 2 L 2 (S) 2 (M = Co 2+ , Ni 2+ or Zn 2+ ; S = MeOH or CH 3 CN) were obtained at À5°C by slow diffusion of ether into solutions of these complexes. When these crystals were re-dissolved in methanol and allowed to grow again at room temperature using the same technique and solvent system, the product obtained presented a 3:1 ratio ligand-to-metal. The complex [Cu(BF 4 ) 2-L 2 (MeOH)](BF 4 ), exhibits two units of L, one molecule of MeOH and one counter-anion coordinated to the Cu 2+ center. This can be attributed to the steric restrictions generated by the lower symmetry in this complex, a product of significant Jahn-Teller effects, which favors a long range interaction between the metal center and a less coordinative counter-anion, compared to a MeOH unit. A 1:1 ligand-to-metal ratio complex of Ni 2+ was also obtained by allowing the starting materials to react for only a short time. Attempts to obtain single crystal of complexes of Co 2+ , Cu 2+ or Zn 2+ in a 1:1 ratio were not successful. The resulting 3:1 ligand-to-metal products were fully characterized by elemental analysis, UV-Vis spectroscopy and FT-IR spectroscopy.

Research paper thumbnail of Syntheses and Coordination Studies of 2-(Phosphanylmethyl)pyridine Dioxide toward Silver (I)

European Journal of Inorganic Chemistry, 2013

The coordination properties of the 2-[(diphenylphosphanyl)methyl]pyridine N,P-dioxide ligand towa... more The coordination properties of the 2-[(diphenylphosphanyl)methyl]pyridine N,P-dioxide ligand towards three different silver(I) salts are described. The molecular structures of the coordination complexes obtained showed a strong dependence on the 2-[(diphenylphosphanyl)methyl]pyridine N,Pdioxide ligand and the binding ability of the counterion. The strongly binding trifluoroacetate ion yielded a unique planar

Research paper thumbnail of SOLICITUD -REGISTRO/AUTORIZACIÓN