Tetranuclear organometallic complexes containing Mo2O42+ and allylmolybdenum(ii) moieties

Paredes, Paloma; López-Calzada, Angel; Miguel, Daniel; Villafañe, Fernando

doi:10.1039/c0dt00570c

Cited by 10 publications

(3 citation statements)

References 62 publications

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“…First, L 1 specifically favors molybdenum in the maximum/minimum oxidation states by utilizing hard (catecholate) and soft (iminopyridine) donors. Second, L 1 likely geometrically precludes the formation of the metal–metal bond usually found in the mixed-valent complexes. – Third, as stated above, efficient π back bonding in the fac -Mo(CO) 3 leads to a particularly stable formally Mo(0) complex. To further demonstrate the fact that the stability of 4 is primarily due to the heterodinucleating ligand L 1 , we investigated the reactivity of Mo(CO) 6 with (Et 4 N) 2 [MoO 4 ] in the absence of L 1 .…”

Section: Results and Discussionmentioning

confidence: 91%

“…There are a significant number of stable mixed-valent dimolybdenum complexes in the literature. Some of these complexes combine molybdenum-oxo and molybdenum-carbonyl functionalities. – Most of these complexes demonstrate intermediate oxidation states of molybdenum, are supported by Mo–Mo bonds, and are obtained from the bimetallic Mo precursor [CpMo(CO) 2 ] 2 . Complex 4 is a rare example in which two molybdenum centers are (1) in their (typical) minimum and maximum oxidation states and (2) the dimolybdenum complex is not supported by a Mo–Mo interaction.…”

Section: Results and Discussionmentioning

confidence: 99%

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Combining [Mo^VIO₃] and [M⁰(CO)₃] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Kaluarachchige Don,

Palmer,

Ward

et al. 2023

Inorg. Chem.

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A functional model of Mo−Cu carbon monoxide dehydrogenase (CODH) enzyme requires the presence of an oxidant (metal-oxo) and a metal-bound carbonyl in close proximity. In this work, we report the synthesis, characterization, and reactivity of a heterobimetallic complex combining Mo(VI) trioxo with Mo(0) tricarbonyl. The formation of the heterobimetallic complex is facilitated by the xanthene-bridged heterodinucleating ligand containing a hard catecholate chelate and a soft iminopyridine chelate. A catechol-coordinated square-pyramidal [Mo VI O 3 ] fragment interacts directly with the iminopyridine-bound [Mo 0 (CO) 3 ] fragment via a single (oxo) bridge, with the overall disposition being related to the proposed first step in the CODH mechanism, where square-pyramidal [Mo VI O 2 S] interacts with the [Cu−CO] via a single sulfido bridge. Our attempt to obtain a sulfido-bridged analogue (using [MoO 3 S] 2− precursor) led to a mixture of products possibly containing different (oxo and sulfido) bridges. Despite a direct interaction between Mo(VI) and Mo(0) segments, no internal redox is observed, with the high lying occupied MOs being mostly d-π orbitals at Mo 0 (CO) 3 and the low lying unoccupied MOs being d-π orbitals at Mo VI O 3 . Due to the overall rigid structure, the heterobimetallic complex was found to be stable up to 100 °C in DMF-d 7 (based on 1 H NMR). The decomposition of the complex above this temperature does not produce CO 2 (based on gas chromatography), dissociating stable Mo(CO) 3 (DMF) 3 instead (based on IR). We also synthesized and studied the reactivity of the Mo(VI)/Cr(0) analogue. While this complex demonstrated more facile decomposition, no CO 2 production was observed. Density functional theory calculations suggest that the formation of [CO 2 ] 2− and its subsequent reductive elimination is endergonic in the present system, likely due to the stability of fac-Mo 0 (CO) 3 and the relative nucleophilic character of the carbonyl carbon engendered by back donation from Mo(0). The calculations also indicate that the replacement of one oxo by sulfido (both terminal and bridging), replacement of catechol with dithiolene, and replacement of Mo(0) with Cr(0) does not affect significantly the energetics of the process, likely requiring the use a less stable and less π-basic CO anchor.

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Section: Results and Discussionmentioning

confidence: 91%

Section: Results and Discussionmentioning

confidence: 99%

Combining [Mo^VIO₃] and [M⁰(CO)₃] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Kaluarachchige Don,

Palmer,

Ward

et al. 2023

Inorg. Chem.

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“…The isomer found in the solid structure may be described as cis, but the presence of a trans isomer in solution can not be discarded. On the other hand, allyldicarbonylmolybdenum(II) complexes usually display a nondissociative trigonal twist process in which there is an intramolecular rotation of the XL 2 triangular face, which would afford new sets of signals if it were slow enough. Finally, the well-known lability of the metal-nitrile bonds (Mo-NCNCN bonds in 1a and 1b ), would lead to decoordination of dicyanamide and eventually to the decomposition of the complex, and in fact the solutions became brown in a few minutes.…”

Section: Resultsmentioning

confidence: 99%

Coordination versus Coupling of Dicyanamide in Molybdenum and Manganese Pyrazole Complexes

et al. 2012

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The reactions of cis-[MoCl(η(3)-methallyl)(CO)(2)(NCMe)(2)] (methallyl = CH(2)C(CH(3))CH(2)) with Na(NCNCN) and pz*H (pzH, pyrazole, or dmpzH, 3,5-dimethylpyrazole) lead to cis-[Mo(η(3)-methallyl)(CO)(2)(pz*H)(μ-NCNCN-κ(2)N,N)](2) (pzH, 1a; dmpzH, 1b), where dicyanamide is coordinated as bridging ligand. Similar reactions with fac-[MnBr(CO)(3)(NCMe)(2)] lead to the pyrazolylamidino complexes fac-[Mn(pz*H)(CO)(3)(NH═C(pz*)NCN-κ(2)N,N)] (pzH, 2a; dmpzH, 2b), resulting from the coupling of pyrazol with one of the CN bonds of dicyanamide. The second CN bond of dicyanamide in 2a undergoes a second coupling with pyrazole after addition of 1 equiv of fac-[MnBr(CO)(3)(pzH)(2)], yielding the dinuclear doubly coupled complex [{fac-Mn(pzH)(CO)(3)}(2)(μ-NH═C(pz)NC(pz)=NH-κ(4)N,N,N,N)]Br (3). The crystal structure of 3 reveals the presence of two isomers, cis or trans, depending on whether the terminal pyrazoles are coordinated at the same or at different sides of the approximate plane defined by the bridging bis-amidine ligand. Only the cis isomer is detected in the crystal structure of the perchlorate salt of the same bimetallic cation (4), obtained by metathesis with AgClO(4). All the N-bound hydrogen atoms of the cations in 3 or 4 are involved in hydrogen bonds. Some of the C-N bonds of the pyrazolylamidino ligand have a character intermediate between single and double, and theoretical studies were carried out on 2a and 3 to confirm its electronic origin and discard packing effects. Calculations also show the essential role of bromide in the planarity of the tetradentate ligand in the bimetallic complex 3.

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Carboxylato Molybdenum(V) Complexes: X-Ray Structures of the Dinuclear Pivalato Complexes

Modec

2013

J Chem Crystallogr

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Tetranuclear organometallic complexes containing Mo2O42+ and allylmolybdenum(ii) moieties

Cited by 10 publications

References 62 publications

Combining [Mo^VIO₃] and [M⁰(CO)₃] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Combining [Mo^VIO₃] and [M⁰(CO)₃] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Coordination versus Coupling of Dicyanamide in Molybdenum and Manganese Pyrazole Complexes

Carboxylato Molybdenum(V) Complexes: X-Ray Structures of the Dinuclear Pivalato Complexes

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Tetranuclear organometallic complexes containing Mo2O42+ and allylmolybdenum(ii) moieties

Cited by 10 publications

References 62 publications

Combining [MoVIO3] and [M0(CO)3] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Combining [MoVIO3] and [M0(CO)3] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Coordination versus Coupling of Dicyanamide in Molybdenum and Manganese Pyrazole Complexes

Carboxylato Molybdenum(V) Complexes: X-Ray Structures of the Dinuclear Pivalato Complexes

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Combining [Mo^VIO₃] and [M⁰(CO)₃] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands

Combining [Mo^VIO₃] and [M⁰(CO)₃] (M = Mo, Cr) Fragments within the Same Complex: Synthesis and Reactivity of the Single Oxo-Bridged Heterobimetallics Supported by Xanthene-Based Heterodinucleating Ligands