Angewandte Chemie (International ed. in English), Jan 31, 2018
The platinum complex [Pt(IBuPr')(IBuPr)][BAr] interacts with tertiary silanes to form stable ... more The platinum complex [Pt(IBuPr')(IBuPr)][BAr] interacts with tertiary silanes to form stable (<0 °C) mononuclear Ptσ-SiH complexes [Pt(IBuPr')(IBuPr)(η-HSiR)][BAr]. These compounds have been fully characterized, including X-ray diffraction methods, as the first examples for platinum. DFT calculations (including electronic topological analysis) support the interpretation of the coordination as an unusual η-SiH. However, the energies required for achieving a η-SiH mode are rather low, and is consistent with the propensity of these derivatives to undergo Si-H cleavage leading to the more stable silyl species [Pt(SiR)(IBuPr)][BAr] at room temperature.
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 19, 2016
The reactivity of cisplatin towards different nucleophiles has been studied by using density func... more The reactivity of cisplatin towards different nucleophiles has been studied by using density functional theory (DFT). Water was considered first to analyze the factors that govern the transformation of cisplatin into more electrophilic aquated species by using an activation-strain model. It was found that the selectivity and reactivity of cisplatin is a delicate trade-off between strain and interaction energies and that the second chloride is a worse leaving group than the first. When similar studies were carried out with imidazole, guanine (G), and adenine (A), it was found that in general the second nucleophilic substitution reactions have lower activation barriers than the first ones. Finally, simulations of the structural restrictions imposed by the DNA scaffold in intra- and interstrand processes showed that the geometries of the reaction products are nonoptimal with respect to the unrestrained A and G nucleophiles, although the energetic cost is not considerable under physiolo...
The referred elongated dihydrogen compounds cannot be described by simply interpolating dihydroge... more The referred elongated dihydrogen compounds cannot be described by simply interpolating dihydrogen and dihydrido models. According to the results reported here, it is more appropriate to describe them as complexes containing two hydrogen atoms moving freely ...
In order to explore possible ways for modulating the unusually rich chemistry shown by complexes ... more In order to explore possible ways for modulating the unusually rich chemistry shown by complexes of formula [L2Pt(mu-S)2PtL2] we have studied the influence of the nature of the terminal ligand L on the chemical properties of the {Pt2(mu-S)2} core. The systematic study we now report allows comparison of the behaviour of [Pt2(dpae)2(mu-S)2](dpae = Ph2As(CH2)2AsPh2) (1) with the already reported analogue [Pt2(dppe)2(mu-S)2](dppe = Ph2P(CH2)2PPh2). Complex 1 as well as the corresponding multimetallic derivatives [Pt(dpae){Pt2(dpae)2(mu-S)2}](BPh4)2 2, [M{Pt2(dpae)2(mu-S)2}2]X2 (M = Cu(II), X = BF4 3; M = Zn(II), X = BPh4 4; M = Cd(II), X = ClO4 5; M = Hg(II), X = Cl 6 or X2 = Cl(1.5)[HCl2](0.5) 6&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;) have been characterized in the solid phase and in solution. Comparison of structural parameters of 1 and 3-6&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; with those of the corresponding phosphine analogues, together with the results of the electrochemical study for 1, allow us to conclude that replacement of dppe by dpae causes a decrease in basicity of the {Pt2(mu-S)2} core. The study of the reactivity of 1 towards CH2Cl2 and protic acids has led to the structural characterization of [Pt(dpae)(S2CH2)] 9 and [PtCl2(dpae)] 10. Moreover, comparison with the reactivity of [Pt2(dppe)2(mu-S)2] indicates that the stability of the intermediate species as well as the nature of the final products in both multistep reactions are sensitive to the nature of the terminal ligand.
ABSTRACT The activation of hydrogen by complexes [Cp&#39;Ru(PTA)(2)Cl] (Cp&#39; = C5H5, C... more ABSTRACT The activation of hydrogen by complexes [Cp&#39;Ru(PTA)(2)Cl] (Cp&#39; = C5H5, C5Me5; PTA = 1,3,5-triaza-7-phosphaadamantane) in water was investigated in a comparative DFT study carried out using a discrete + continuum model based on a four-water-molecule cluster. As a starting point were chosen the eta(2)-H-2 dihydrogen complexes [Cp&#39;Ru(PTA)(2)(eta(2)-H-2)](+) (1H(2)), which are formed initially upon reaction of the chloride precursors with hydrogen gas. A rationale for the experimental data, showing that the monohydrido complex [CpRu(PTA)PTA(H)H](+) (4a) and the dihydrido complex [Cp*Ru(PTA)(2)(H)(2)]Cl (3b) are the stable products for the two systems, is proposed, together with an in-depth analysis of both ligand and solvent effects in the stability of the different species, leading to more general mechanistic implications for metal-mediated hydrogen activation in water.
IMOMM (Becke3LYP:MM3) calculations are performed on different proposed intermediates in the react... more IMOMM (Becke3LYP:MM3) calculations are performed on different proposed intermediates in the reaction pathway of biomimetic models of catalase and peroxidase enzymes. These calculations allow the identification of their ground state, structural features and relative energies. The relative energies are shown to depend heavily on the nature of the substrates involved in the reaction, and they are analyzed in detail for the case of the oxidation of alcohol to aldehyde by hydrogen peroxide. All the considered intermediates are found to be within a reasonable energy span.
The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2... more The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 3, dppp (1); n = 2, dppe (2)) metalloligands toward the CH(2)Cl(2) solvent has been thoroughly studied. Complex 1, which has been obtained and characterized by X-ray diffraction, is structurally related to 2 and consists of dinuclear molecules with a hinged [Pt(2)S(2)] central ring. The reaction of 1 and 2 with CH(2)Cl(2) has been followed by means of (31)P, (1)H, and (13)C NMR, electrospray ionization mass spectrometry, and X-ray data. Although both reactions proceed at different rates, the first steps are common and lead to a mixture of the corresponding mononuclear complexes [Pt[Ph(2)P(CH(2))(n)PPh(2)](S(2)CH(2))], n = 3 (7), 2 (8), and [Pt[Ph(2)P(CH(2))(n)PPh(2)]Cl(2)], n = 3 (9), 2 (10). Theoretical calculations give support to the proposed pathway for the disintegration process of the [Pt(2)S(2)] ring. Only in the case of 1, the reaction proceeds further yielding [Pt(2)(dppp)(2)[mu-(SCH(2)SCH(2)S)-S,S&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;]]Cl(2) (11). To confirm the sequence of the reactions leading from 1 and 2 to the final products 9 and 11 or 8 and 10, respectively, complexes 7, 8, and 11 have been synthesized and structurally characterized. Additional experiments have allowed elucidation of the reaction mechanism involved from 7 to 11, and thus, the origin of the CH(2) groups that participate in the expansion of the (SCH(2)S)(2-) ligand in 7 to afford the bridging (SCH(2)SCH(2)S)(2-) ligand in 11 has been established. The X-ray structure of 11 is totally unprecedented and consists of a hinged [(dppp)Pt(mu-S)(2)Pt(dppp)] core capped by a CH(2)SCH(2) fragment.
Computational chemistry is a valuable aid to complement experimental studies of organometallic sy... more Computational chemistry is a valuable aid to complement experimental studies of organometallic systems and their reactivity. It allows probing mechanistic hypotheses and investigating molecular structures, shedding light on the behavior and properties of molecular assemblies at the atomic scale. When approaching a chemical problem, the computational chemist has to decide on the theoretical approach needed to describe electron/nuclear interactions and the composition of the model used to approximate the actual system. Both factors determine the reliability of the modeling study. The community dedicated much effort to developing and improving the performance and accuracy of theoretical approaches for electronic structure calculations, on which the description of (inter)atomic interactions rely. Here, the importance of the model system used in computational studies is highlighted through examples from our recent research focused on organometallic systems and homogeneous catalytic proce...
Angewandte Chemie (International ed. in English), Jan 31, 2018
The platinum complex [Pt(IBuPr')(IBuPr)][BAr] interacts with tertiary silanes to form stable ... more The platinum complex [Pt(IBuPr')(IBuPr)][BAr] interacts with tertiary silanes to form stable (<0 °C) mononuclear Ptσ-SiH complexes [Pt(IBuPr')(IBuPr)(η-HSiR)][BAr]. These compounds have been fully characterized, including X-ray diffraction methods, as the first examples for platinum. DFT calculations (including electronic topological analysis) support the interpretation of the coordination as an unusual η-SiH. However, the energies required for achieving a η-SiH mode are rather low, and is consistent with the propensity of these derivatives to undergo Si-H cleavage leading to the more stable silyl species [Pt(SiR)(IBuPr)][BAr] at room temperature.
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 19, 2016
The reactivity of cisplatin towards different nucleophiles has been studied by using density func... more The reactivity of cisplatin towards different nucleophiles has been studied by using density functional theory (DFT). Water was considered first to analyze the factors that govern the transformation of cisplatin into more electrophilic aquated species by using an activation-strain model. It was found that the selectivity and reactivity of cisplatin is a delicate trade-off between strain and interaction energies and that the second chloride is a worse leaving group than the first. When similar studies were carried out with imidazole, guanine (G), and adenine (A), it was found that in general the second nucleophilic substitution reactions have lower activation barriers than the first ones. Finally, simulations of the structural restrictions imposed by the DNA scaffold in intra- and interstrand processes showed that the geometries of the reaction products are nonoptimal with respect to the unrestrained A and G nucleophiles, although the energetic cost is not considerable under physiolo...
The referred elongated dihydrogen compounds cannot be described by simply interpolating dihydroge... more The referred elongated dihydrogen compounds cannot be described by simply interpolating dihydrogen and dihydrido models. According to the results reported here, it is more appropriate to describe them as complexes containing two hydrogen atoms moving freely ...
In order to explore possible ways for modulating the unusually rich chemistry shown by complexes ... more In order to explore possible ways for modulating the unusually rich chemistry shown by complexes of formula [L2Pt(mu-S)2PtL2] we have studied the influence of the nature of the terminal ligand L on the chemical properties of the {Pt2(mu-S)2} core. The systematic study we now report allows comparison of the behaviour of [Pt2(dpae)2(mu-S)2](dpae = Ph2As(CH2)2AsPh2) (1) with the already reported analogue [Pt2(dppe)2(mu-S)2](dppe = Ph2P(CH2)2PPh2). Complex 1 as well as the corresponding multimetallic derivatives [Pt(dpae){Pt2(dpae)2(mu-S)2}](BPh4)2 2, [M{Pt2(dpae)2(mu-S)2}2]X2 (M = Cu(II), X = BF4 3; M = Zn(II), X = BPh4 4; M = Cd(II), X = ClO4 5; M = Hg(II), X = Cl 6 or X2 = Cl(1.5)[HCl2](0.5) 6&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;) have been characterized in the solid phase and in solution. Comparison of structural parameters of 1 and 3-6&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; with those of the corresponding phosphine analogues, together with the results of the electrochemical study for 1, allow us to conclude that replacement of dppe by dpae causes a decrease in basicity of the {Pt2(mu-S)2} core. The study of the reactivity of 1 towards CH2Cl2 and protic acids has led to the structural characterization of [Pt(dpae)(S2CH2)] 9 and [PtCl2(dpae)] 10. Moreover, comparison with the reactivity of [Pt2(dppe)2(mu-S)2] indicates that the stability of the intermediate species as well as the nature of the final products in both multistep reactions are sensitive to the nature of the terminal ligand.
ABSTRACT The activation of hydrogen by complexes [Cp&#39;Ru(PTA)(2)Cl] (Cp&#39; = C5H5, C... more ABSTRACT The activation of hydrogen by complexes [Cp&#39;Ru(PTA)(2)Cl] (Cp&#39; = C5H5, C5Me5; PTA = 1,3,5-triaza-7-phosphaadamantane) in water was investigated in a comparative DFT study carried out using a discrete + continuum model based on a four-water-molecule cluster. As a starting point were chosen the eta(2)-H-2 dihydrogen complexes [Cp&#39;Ru(PTA)(2)(eta(2)-H-2)](+) (1H(2)), which are formed initially upon reaction of the chloride precursors with hydrogen gas. A rationale for the experimental data, showing that the monohydrido complex [CpRu(PTA)PTA(H)H](+) (4a) and the dihydrido complex [Cp*Ru(PTA)(2)(H)(2)]Cl (3b) are the stable products for the two systems, is proposed, together with an in-depth analysis of both ligand and solvent effects in the stability of the different species, leading to more general mechanistic implications for metal-mediated hydrogen activation in water.
IMOMM (Becke3LYP:MM3) calculations are performed on different proposed intermediates in the react... more IMOMM (Becke3LYP:MM3) calculations are performed on different proposed intermediates in the reaction pathway of biomimetic models of catalase and peroxidase enzymes. These calculations allow the identification of their ground state, structural features and relative energies. The relative energies are shown to depend heavily on the nature of the substrates involved in the reaction, and they are analyzed in detail for the case of the oxidation of alcohol to aldehyde by hydrogen peroxide. All the considered intermediates are found to be within a reasonable energy span.
The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2... more The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 3, dppp (1); n = 2, dppe (2)) metalloligands toward the CH(2)Cl(2) solvent has been thoroughly studied. Complex 1, which has been obtained and characterized by X-ray diffraction, is structurally related to 2 and consists of dinuclear molecules with a hinged [Pt(2)S(2)] central ring. The reaction of 1 and 2 with CH(2)Cl(2) has been followed by means of (31)P, (1)H, and (13)C NMR, electrospray ionization mass spectrometry, and X-ray data. Although both reactions proceed at different rates, the first steps are common and lead to a mixture of the corresponding mononuclear complexes [Pt[Ph(2)P(CH(2))(n)PPh(2)](S(2)CH(2))], n = 3 (7), 2 (8), and [Pt[Ph(2)P(CH(2))(n)PPh(2)]Cl(2)], n = 3 (9), 2 (10). Theoretical calculations give support to the proposed pathway for the disintegration process of the [Pt(2)S(2)] ring. Only in the case of 1, the reaction proceeds further yielding [Pt(2)(dppp)(2)[mu-(SCH(2)SCH(2)S)-S,S&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;]]Cl(2) (11). To confirm the sequence of the reactions leading from 1 and 2 to the final products 9 and 11 or 8 and 10, respectively, complexes 7, 8, and 11 have been synthesized and structurally characterized. Additional experiments have allowed elucidation of the reaction mechanism involved from 7 to 11, and thus, the origin of the CH(2) groups that participate in the expansion of the (SCH(2)S)(2-) ligand in 7 to afford the bridging (SCH(2)SCH(2)S)(2-) ligand in 11 has been established. The X-ray structure of 11 is totally unprecedented and consists of a hinged [(dppp)Pt(mu-S)(2)Pt(dppp)] core capped by a CH(2)SCH(2) fragment.
Computational chemistry is a valuable aid to complement experimental studies of organometallic sy... more Computational chemistry is a valuable aid to complement experimental studies of organometallic systems and their reactivity. It allows probing mechanistic hypotheses and investigating molecular structures, shedding light on the behavior and properties of molecular assemblies at the atomic scale. When approaching a chemical problem, the computational chemist has to decide on the theoretical approach needed to describe electron/nuclear interactions and the composition of the model used to approximate the actual system. Both factors determine the reliability of the modeling study. The community dedicated much effort to developing and improving the performance and accuracy of theoretical approaches for electronic structure calculations, on which the description of (inter)atomic interactions rely. Here, the importance of the model system used in computational studies is highlighted through examples from our recent research focused on organometallic systems and homogeneous catalytic proce...
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