Nitrido Dimers and Trimers of Tungsten Supported by tBuMe2SiO and CF3Me2CO Ligands, Respectively. Factors Influencing the Reductive Cleavage of Nitriles by Tungsten–Tungsten Triple Bonds and An Analysis of the Structure of the Cyclotrimer

Chisholm, Malcolm H.; Folting, Kirsten; Lynn, Matthew A.; Tiedtke, Darin B.; Lemoigno, Frédéric; Eisenstein, Odile

doi:10.1002/(sici)1521-3765(19990802)5:8<2318::aid-chem2318>3.3.co;2-7

Cited by 22 publications

(31 citation statements)

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“…Introduction of the electron‐donating R 2 group retards the reaction of the second slow step; with R 1 = H and R 2 = Bu t , 54 becomes isolable because of a slow conversion from 54 to 55 . The mechanism demonstrated here is quite different from the other precedented examples of the C≡N bond cleavage; [W(CBu t )(2,6‐diisopropylphenoxide) 3 ] and [W 2 (OR) 6 ] (R = Bu t , CMe 2 CF 3 ) are transformed into nitrido complexes in the reaction with nitriles, where a metathesis‐type mechanism has been postulated 93–96…”

Section: Transformation Of Nitrilescontrasting

confidence: 57%

Transformation of organic molecules on the low‐valent {M(Ph₂PCH₂CH₂PPh₂)₂} moiety derived from trans‐[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] or related complexes (M = MO, W)

Seino

Mizobe

Hidai

2001

The Chemical Record

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A zero-valent [M(Ph(2)PCH(2)CH(2)PPh(2))(2)] moiety (M = Mo, W) generated in situ by dissociation of the N(2) ligands in trans-[M(N(2))(2)(Ph(2)PCH(2)CH(2)PPh(2))(2)] can activate pi-accepting organic molecules including isocyanides and nitriles, which undergo the electrophilic attack caused by a strong pi-donation from a zero-valent metal center. Cleavage of a variety of C-X bonds (X = H, C, N, O, P, halogen) also occurs at their electron-rich sites through oxidative addition to form reactive intermediates, which subsequently degradate to yield smaller molecules either bound to or dissociated from the metal center. The mechanism is substantiated unambiguously by isolation of numerous intermediate stages.

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Section: Transformation Of Nitrilescontrasting

confidence: 57%

Transformation of organic molecules on the low‐valent {M(Ph₂PCH₂CH₂PPh₂)₂} moiety derived from trans‐[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] or related complexes (M = MO, W)

Seino

Mizobe

Hidai

2001

The Chemical Record

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“…Such perpendicular coordination seems to be effective for back‐donation from metal centers to the π*(CN) orbital. In the reaction of the ditungsten complex [W 2 (OCMe 2 CF 3 ) 6 ] with nitrile, an intermediate with a perpendicularly coordinated nitrile ligand to the WW bond has been proposed for the formation of a nitrido complex by Chisholm and co‐workers 9d. Hidai and co‐workers elucidated that strong π donation from a low‐valent metal center enhances nucleophilicity of the cyano carbon atom, which causes double protonation at this atom leading to CN bond scission 9e–g…”

mentioning

confidence: 99%

Cleavage of the CN Bond on a Triruthenium Cluster: Synthesis and Structure of a Triruthenium Complex Containing a μ₃‐Nitrido Ligand

Kawashima¹,

Takao²,

Suzuki³

2006

Angew Chem Int Ed

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Since a nitrile group contains an sp hybridized nitrogen atom as well as dinitrogen, cleavage of the CN bond of nitrile is regarded as an analogue of NN bond activation of dinitrogen. The nitrogenase enzyme was shown to catalyze reductive cleavage of the CN bond of nitrile.[1] Carbon-nitrogen bond cleavage of nitrile by using the dimolybdenum sulfido complex [(CpMo) 2 (S 2 CH 2 )(m-S)(m-SH)]under a dihydrogen atmosphere was demonstrated by Rakowski DuBois and co-workers.[2] Heterolytic cleavage of dihydrogen by the sulfido complex was proposed as a prerequisite for further CÀN bond cleavage. In general, the electronic property of the hydrido ligand continuously changes from "protonic" to "hydridic" depending upon whether it is combined with a metal center, thus the polyhydrido cluster effectively cleaves the CN bond of nitrile. We report herein cleavage of the CN bond of nitrile in the reaction of a triruthenium hydrido complex. Transformation of a nitrile ligand on a triiron framework has been elucidated in the pioneering studies performed by Kaesz and co-workers.[3] They showed step-wise reduction of a m 3 -nitrile ligand to give a m 3 -imido ligand through formation of a m 3 -alkylideneamido complex upon treatment with dihydrogen. In spite of several studies with trimetallic carbonyl clusters of iron, [3, 4] ruthenium, [5] and osmium, [6] C N bond cleavage has never been observed. [7] The m 3 -nitrido ligand of 2 was formed as a result of CN bond cleavage of benzonitrile. While there have been numerous examples of the CN bond cleavage of nitrile by way of hydration, [8] CN bond scission to form a metal nitride is rare. [9] To the best of our knowledge, this is the first example of C N bond cleavage performed on a trimetallic complex to form a m 3 -nitrido ligand.The molecular structure of 2 was determined by an X-ray diffraction study (Figure 1). [10] Although distinction between a m 3 -nitrido and a m 3 -imido ligand only on the basis of the Xray diffraction study is difficult, the diamagnetic property of 2 rules out the presence of a m 3 -NH group in 2; an 1 H NMR signal of the hydrido ligand was observed at d = À23.02 ppm. This is the first example of a m 3 -nitrido cluster complex for late transition metals, while several cubane-type complexes are known.[11] Structural parameters of 2 were quite similiar to those of isoelectronic and isostructural m 3 -methylidyne analogue, [(Cp*Ru) 3 (m 3 -CH)(m 3 -h 1 :h 3 :h 1 -CHCMeCH)(m-H)] (3). [12] This implies that the m 3 -nitrido ligand adopts an sp 3 configuration. In the case that the m 3 -N ligand is a threeelectron donor, complex 2 becomes diamagnetic and satisfies the 48-electron configuration. The RuÀN bond lengths (Ru(1)ÀN(1) = 2.037(5) , Ru(2)ÀN(1) = 1.922(6) , and Ru(3)ÀN(1) = 1.942(6) ) are similar to those found for the m 3 -imido complexes, [{Cp*Ru(m-H)} 3 (m 3 -NR)] and [(Cp*Ru) 3 (m 3 -NR)(m 3 -NR')(m-H)].

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“…When R = CMe 2 CF 3 , Schrock noted that MeCN reacts reversibly to give W 2 (OCMe 2 CF 3 ) 6 (NCMe) 2 30, which is presumably structurally related to the well‐ characterized Lewis base adducts M 2 (OR) 6 L 2 , e.g., L = py, PMe 3 , or an amine, which have two four‐coordinated metal atoms united by a M‐M triple bond 31. We recently reinvestigated this reaction and studied the equilibrium shown in 11 for both M = Mo and W and for R = Me and aryl 32…”

Section: Resultsmentioning

confidence: 99%

“…Similar reactivity was observed for W 2 (OSiMe t Bu 2 ) 6 , which also gave ( t Bu 2 MeSiO) 3 W≡N and PhC≡CPh. The molecular structures of these nitrides were of interest, with the fluoro alkoxide being a cyclotrimer with alternating W‐N short (double) and long (single) bond distances 32. It was also noted that the rate of cleavage of PhC≡N was suppressed with increasing [PhC≡N] concentration in the range 10 to 40 equivalents.…”

Section: Resultsmentioning

confidence: 99%

Factors influencing the reductive cleavage of C-X multiple bonds in their reactions with metal-metal multiple bonds (X = C, N, O, S)

Chisholm¹

2001

Chem. Record

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Though metal-metal multiple bonds of the transition elements are redox active, their reactivity towards C-X multiple bonds (X = C, N, O, S) vary greatly depending principally on: 1. The coordination geometry of the metal. 2. The oxidation state of the metal and the electronic configuration of the M-M bond. 3. The nature of the attendant ligands. Specific examples of C-X multiple bond activation at dimolybdenum and ditungsten centers are presented that illustrate the importance of these factors. Evidence is presented to support the view that reductive cleavage of a C-X multiple bond can be considered to be equivalent to an intramolecular redox reaction within a [M2CX] "cluster complex," for which the frontier orbital energies of the C-X and M-M multiple bonds are of paramount importance. Some applications of these C-X reductive cleavage reactions toward organic synthesis are described.

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Nitrido Dimers and Trimers of Tungsten Supported by tBuMe2SiO and CF3Me2CO Ligands, Respectively. Factors Influencing the Reductive Cleavage of Nitriles by Tungsten–Tungsten Triple Bonds and An Analysis of the Structure of the Cyclotrimer

Cited by 22 publications

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Transformation of organic molecules on the low‐valent {M(Ph₂PCH₂CH₂PPh₂)₂} moiety derived from trans‐[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] or related complexes (M = MO, W)

Transformation of organic molecules on the low‐valent {M(Ph₂PCH₂CH₂PPh₂)₂} moiety derived from trans‐[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] or related complexes (M = MO, W)

Cleavage of the CN Bond on a Triruthenium Cluster: Synthesis and Structure of a Triruthenium Complex Containing a μ₃‐Nitrido Ligand

Factors influencing the reductive cleavage of C-X multiple bonds in their reactions with metal-metal multiple bonds (X = C, N, O, S)

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Nitrido Dimers and Trimers of Tungsten Supported by tBuMe2SiO and CF3Me2CO Ligands, Respectively. Factors Influencing the Reductive Cleavage of Nitriles by Tungsten–Tungsten Triple Bonds and An Analysis of the Structure of the Cyclotrimer

Cited by 22 publications

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Transformation of organic molecules on the low‐valent {M(Ph2PCH2CH2PPh2)2} moiety derived from trans‐[M(N2)2(Ph2PCH2CH2PPh2)2] or related complexes (M = MO, W)

Transformation of organic molecules on the low‐valent {M(Ph2PCH2CH2PPh2)2} moiety derived from trans‐[M(N2)2(Ph2PCH2CH2PPh2)2] or related complexes (M = MO, W)

Cleavage of the CN Bond on a Triruthenium Cluster: Synthesis and Structure of a Triruthenium Complex Containing a μ3‐Nitrido Ligand

Factors influencing the reductive cleavage of C-X multiple bonds in their reactions with metal-metal multiple bonds (X = C, N, O, S)

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Transformation of organic molecules on the low‐valent {M(Ph₂PCH₂CH₂PPh₂)₂} moiety derived from trans‐[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] or related complexes (M = MO, W)

Transformation of organic molecules on the low‐valent {M(Ph₂PCH₂CH₂PPh₂)₂} moiety derived from trans‐[M(N₂)₂(Ph₂PCH₂CH₂PPh₂)₂] or related complexes (M = MO, W)

Cleavage of the CN Bond on a Triruthenium Cluster: Synthesis and Structure of a Triruthenium Complex Containing a μ₃‐Nitrido Ligand