Nature and Strength of Metal−Chalcogen Multiple Bonds in High Oxidation State Complexes

González-Blanco, Òscar; Branchadell, V.; Monteyne, Kereen; Ziegler, Tom

doi:10.1021/ic970613l

Cited by 24 publications

(19 citation statements)

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“…Consideration of the literature indicates that for many systems involving bonds to sulfur and selenium, e.g. E–H,6d E–C6d, E–P,47 and E–transition metal48,49,50 (E = S, Se), the bond to sulfur is generally the stronger; however, there are situations in which the reverse is observed. For example, the opposite trend has been observed for coordination of thio- and selenoethers to transition metals 51.…”

Section: Resultsmentioning

confidence: 99%

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [Tm^{Bu^t}]HgSePh and Its Relevance to the Toxicity of Mercury

2009

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One of the reasons for the toxic effects of mercury has been attributed to its influence on the biochemical roles of selenium. For this reason, it is important to understand details pertaining to the nature of Hg-Se interactions and this has been achieved by comparison of a series of mercury chalcogenolate complexes that are supported by tris (2-mercapto-1-t-butyl-imidazolyl) ]CdEPh, the Hg-EPh bonds are actually shorter than the corresponding Cd-EPh bonds, an observation which indicates that the apparent covalent radii of the metals in these compounds are dependent on the nature of the bonds. Furthermore, the difference in Hg-EPh and Cd-EPh bond lengths is a function of the chalcogen and increases in the sequence S (0.010 Å) < Se (0.035 Å) < Te (0.057 Å). This trend indicates that the chalcogenophilicity of mercury increases in the sequence S < Se < Te. Thus, while mercury is often described as being thiophilic, it is evident that it actually has a greater selenophilicity, a notion that is supported by the observation of facile selenolate transfer from zinc to mercury upon treatment of [Tm Bu t ]HgSCH 2 C(O)N(H)Ph with [Tm Bu t ]ZnSePh. The significant selenophilicity of mercury is in accord with the aforementioned proposal that one reason for the toxicity of mercury is associated with it reducing the bioavailability of selenium.

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Section: Resultsmentioning

confidence: 99%

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [Tm^{Bu^t}]HgSePh and Its Relevance to the Toxicity of Mercury

2009

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“…Recently, the BDE's of the four-coordinate Mo(V) complexes [MoQ(N[R]Ar) 3 ] were calorimetrically determined in solution . The values are 156 kcal/mol for Q = O and 104 kcal/mol for Q = S. Other MoO BDE's have been determined or theoretically estimated to fall in the 126−158 kcal/mol range. − Density functional calculations afford BDE's of 126 and 79 kcal/mol for [MoOCl 4 ] and [MoSCl 4 ], respectively …”

Section: Resultsmentioning

confidence: 99%

“…58 The values are 156 kcal/mol for Q ) O and 104 kcal/mol for Q ) S. Other ModO BDE's have been determined or theoretically estimated to fall in the 126-158 kcal/mol range. [59][60][61][62][63] Density functional calculations afford BDE's of 126 and 79 kcal/mol for [MoOCl 4 ] and [MoSCl 4 ], respectively. 63 Although the data are limited and do not apply to six-coordinate Mo(VI), a reasonable conclusion at this stage is that ModO/ ModS bond energy differences favor sulfur atom abstraction in the general case.…”

Section: Resultsmentioning

confidence: 99%

The Unperturbed Oxo−Sulfido Functional Group cis-Mo^VIOS Related to That in the Xanthine Oxidase Family of Molybdoenzymes: Synthesis, Structural Characterization, and Reactivity Aspects

et al. 1999

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The oxo-sulfido functional group cis-MoVIOS is essential to the activity of the xanthine oxidase family of enzymes but has proven elusive to synthesis in molecules containing no other four-electron ligands. A direct route to molecules containing this group has been achieved. The reaction system [MoO2(OSiPh3)2]/L in dichloromethane yields the complexes [MoVIO2(OSiPh3)2L] (L = phen (1), Me4phen (2), 4,4‘-Me2bpy (3), 5,5‘-Me2bpy (4), 2 py (5)) (74−96%), which are shown to have a distorted octahedral structure of crystallographically imposed C 2 symmetry (1, 5) with cis oxo and trans silyloxy ligands. The related reaction system [MoO3S]2-/2Ph3SiCl/L in acetonitrile affords the complexes [MoVIOS(OSiPh3)2L] (L = phen (6), Me4phen (7), 4,4‘-Me2bpy (8), 5,5‘-Me2bpy (9)) (36−69%). From the collective results of elemental analysis, mass spectrometry, 1H NMR, and X-ray structure determinations (6, 7), complexes 6−9 are shown to contain the cis-MoVIOS group in molecules with the same overall stereochemistry as dioxo complexes 1−5. The crystal structures of 6 and 7 exhibit O/S disorder, which was modeled in refinements with 50% site occupancies. The MoO (1.607(5) (6), 1.645(5) (7) Å) and MoS (2.257(3) (6), 2.203(2) (7) Å) bond distances obtained in this way are somewhat shorter and longer, respectively, than expected. Distances obtained by molybdenum EXAFS analysis using the GNXAS protocol for 6−9 (MoO 1.71−1.72 Å; MoS 2.18−2.19 Å) are considered more satisfactory and are in good agreement with EXAFS values for xanthine oxidase. Molybdenum K-edge data for 1 and 6−9 are reported. Reaction of 7 with Ph3P in dichloromethane results in sulfur abstraction and formation of [MoVOCl(OSiPh3)2(Me4phen)] (10), which has a distorted octahedral structure with cis O/Cl and cis silyloxy ligands. Sulfur rather than oxygen abstraction is favored by relative MoO/MoS bond strengths. Complexes 6−9 should allow exploration of the biologically significant cis-MoVIOS group.

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“…The Δ H (Mo−E) bond formation enthalpies are given in Table as Δ H (Mo−O) = −153.5 kcal/mol, Δ H (Mo−S) = −106.7 kcal/mol, and Δ H (Mo−Se) = −93.6 kcal/mol, respectively. The trend is set by a decrease in the π-overlaps as well as the electronegativity of the chalcogenides through E = O, S, Se, as discussed in more detail by Gonzalez-Blanco et al We include as well for comparison the enthalphy of formation of one Mo−Cl bond in MoCl 2 O 2 from MoClO 2 and Cl as Δ H (Mo−Cl) = −81.2 kcal/mol, Table .…”

Section: Resultsmentioning

confidence: 99%

The [2+2] Addition of Ethylene to Metal−Ligand Multiple Bonds: A Density Functional Study of Mo(E)OCl₂

Monteyne

Ziegler

1998

Organometallics

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We have studied the [2+2] cycloaddition of ethylene to Mo(E)OCl2 for E = S, Se, O, NH, PH, SiH2, and CH2 based on gradient-corrected density functional theory. The reactant Mo(E)OCl2 has for E = NH, PH, SiH2, and CH2 a preferred conformation with all atoms of the E ligand in the plane bisecting the Cl−Mo−Cl angle. The [2+2] cycloaddition takes place with ethylene approaching Mo(E)OCl2 perpendicular to the plane bisecting the Cl−Mo−Cl angle. The reaction enthalpy follows the order (in kcal/mol) SiH2 (−24.1) < CH2 (−15.6) < PH (−7.4) < NH (−0.9) < S (5.9) < Se (6.2) < O (12.0) < Cl (13.0). The ligands with the less electronegative heteroatom give rise to the more exothermic reaction, as they have lone pairs of sufficiently high energy to donate charge to π* of the incoming olefin and form a strong C−E bond. The activation energy for the addition follows the order (in kcal/mol) SiH2 (2.3) < CH2 (4.7) < PH (5.0) < S(16.6) < Se (16.6) < Cl (19.0) < NH (21.1) < O (25.8). Again, ligands with the less electronegative heteroatoms afford the lowest barrier for the addition since they have lone pairs that at an early stage of the reaction can interact, stabilizing with π* of the incoming ethylene. The investigation affords a rationale for why [2+2] addition of olefin to ME bonds is observed experimentally to be facile for E = SiH2 and CH2 but not for E = O.

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Nature and Strength of Metal−Chalcogen Multiple Bonds in High Oxidation State Complexes

Cited by 24 publications

References 40 publications

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [Tm^{Bu^t}]HgSePh and Its Relevance to the Toxicity of Mercury

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [Tm^{Bu^t}]HgSePh and Its Relevance to the Toxicity of Mercury

The Unperturbed Oxo−Sulfido Functional Group cis-Mo^VIOS Related to That in the Xanthine Oxidase Family of Molybdoenzymes: Synthesis, Structural Characterization, and Reactivity Aspects

The [2+2] Addition of Ethylene to Metal−Ligand Multiple Bonds: A Density Functional Study of Mo(E)OCl₂

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Nature and Strength of Metal−Chalcogen Multiple Bonds in High Oxidation State Complexes

Cited by 24 publications

References 40 publications

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [TmBut]HgSePh and Its Relevance to the Toxicity of Mercury

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [TmBut]HgSePh and Its Relevance to the Toxicity of Mercury

The Unperturbed Oxo−Sulfido Functional Group cis-MoVIOS Related to That in the Xanthine Oxidase Family of Molybdoenzymes: Synthesis, Structural Characterization, and Reactivity Aspects

The [2+2] Addition of Ethylene to Metal−Ligand Multiple Bonds: A Density Functional Study of Mo(E)OCl2

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On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [Tm^{Bu^t}]HgSePh and Its Relevance to the Toxicity of Mercury

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [Tm^{Bu^t}]HgSePh and Its Relevance to the Toxicity of Mercury

The Unperturbed Oxo−Sulfido Functional Group cis-Mo^VIOS Related to That in the Xanthine Oxidase Family of Molybdoenzymes: Synthesis, Structural Characterization, and Reactivity Aspects

The [2+2] Addition of Ethylene to Metal−Ligand Multiple Bonds: A Density Functional Study of Mo(E)OCl₂