Molekül- und Kristallstruktur von Bis[chloro(μ-phenylimido)(η5-pentamethylcyclopentadienyl)tantal(IV)](Ta-Ta), [{TaCl(μ-NPh)Cp*}2]

“…30 Reduction of [TaCl 2 (NPh)Cp*] affords the unusual Ta() bimetallic species [{TaCl(µ-NPh)Cp* 2 } 2 ]. 31 Hydrogenation of [(NPN)TaMe 3 ] [NPN = PhP(CH 2 SiMe 2 -NPh) 2 ] affords diamagnetic [{(NPN)Ta} 2 (µ-H) 4 ], which reacts with N 2 to give the unprecedented η 1 :η 2 -N 2 complex 3 (Scheme 2). The end-on:side-on bonding mode was analysed using DFT methods and the principal bonding interactions identified.…”

Section: Vanadium Niobium and Tantalummentioning

confidence: 99%

21 Organometallic chemistry of bi- and poly-nuclear complexes

Low

2002

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

View full text Add to dashboard Cite

The dianion [Mo 2 (CO) 10 ] 2Ϫ was formed together with [Mo(O 2 CNMe 2 )(CO) 4 )] Ϫ following reaction of [Mo(CO) 6 ] with C(NMe 2 ) 4 , and isolated as the [C(NMe 2 ) 3 ] ϩ salt. 33 The structure, bonding, and photochemical behaviour of [M 2 (CO) 6 Cp 2 ] (M = Cr, Mo, W) together with substituted derivatives have been reviewed. 34 This work is complimented by reports which deal with solvent effects upon the formation of Mo-Mo dimers by radical self-termination of [Mo(CO) 3 (η 5 -C 5 H 4 Bu n )] ؒ , 35 and the photochemistry of the parent dimer in supercritical CO 2 . 36 Cleavage of the metal-metal bond in [Cr 2 (CO) 6 -Cp 2 ] and [Cr 2 (CO) 4 Cp 2 ] occurs upon reaction with bis(thiophosphoryl)disulfanes to give complexes featuring S 2 P(OR) 2 ligands. 37 Similar reactions with tetraalkylthiuram disulfides [R 2 NC(S)S] 2 resulted in Cr-Cr bond cleavage to give [Cr(S 2 CNR 2 )(CO) 2 Cp] at room temperature, while under more forcing conditions Cr 4 S 4 Cp n cubane derivatives were obtained, including the first dithiooxamide-bridged and doubly dithiocarbamate-bridged double cubanes: [Cp 6 Cr 8 S 8 {(C(S)NEt 2 ) 2 }] and [Cp 6 Cr 8 S 8 -(S 2 CNEt 2 ) 2 ]. 38 The chromium oxo-cubane [Cp*Cr(µ 3 -O)] 4 can be oxidised by both AgBF 4 or tcnq to give salts containing the [Cp*Cr(µ 3 -O)] 4 ϩ cation, which features significantly contracted Cr-Cr, Cr-O and Cr-Cp* distances. All of these cubanes are antiferromagnetic, with intra-cluster exchange coupling constants J = Ϫ211 to Ϫ266 cm Ϫ1 . Electrochemical studies of the series [CpЈCr(µ 3 -O)] 4 (CpЈ = Cp, Cp Me , Cp*) revealed that a dication can also be electrochemically generated in the case of complexes featuring the more electron donating Cp Me and Cp* ligands. The Cp complex can be reduced to the mono-anion. 39 Reduction of [Mo 2 (µ-S 2 CPCy 3 )(µ-Br)(CO) 5 (η 3 -C 3 H 5 )] (Na/Hg) affords the anion [Mo 2 (µ-S 2 CPCy 3 )(CO) 5 (η 3 -C 3 H 5 )] Ϫ , which reacts with ClCH 2 CMe᎐ ᎐ CH 2 to give the bis(allyl) complex [Mo 2 (µ-S 2 CPCy 3 )(CO) 5 (η 3 -C 3 H 5 )(η 3 -H 2 CCMeCH 2 )] (5), in which Scheme 2

show abstract

Four‐Electron Oxidative Formation of Aryl Diazenes Using a Tantalum Redox‐Active Ligand Complex

Zarkesh

Heyduk

2008

Angewandte Chemie

View full text Add to dashboard Cite

Transition-metal complexes capable of mediating multielectron transformations are critical components for a variety of small-molecule transformations. For example, the oxidation of CÀH bonds [1] and the reduction of protons to H 2 [2] are both two-electron transformations. The oxidation of water to O 2 is a four-electron process [3] and the reduction of nitrogen to ammonia is an overall six-electron process.[4] The design of metal complexes to promote or catalyze these multielectron reactions usually relies on one or more transition-metal ions capable of two-electron changes in a formal oxidation state. An alternative strategy is to incorporate redox-active ligands into the metal coordination sphere to supply reducing or oxidizing equivalents during a multielectron transformation.[5]Herein, we report the use of a tridentate redox-active ligand,, [6] coordinated to tantalum, to effect the fourelectron oxidative formation of aryl diazenes. In its reduced form, [ONO red ] 3À is a planar, tridentate ligand that coordinates to transition metals in a meridional geometry. The organometallic synthon TaMe 3 Cl 2 [7] has been used to prepare [ONO red ]TaMe 2 (1), which was then converted into the; 2 b, L = pyridine (py); Scheme 1). Oxidation of 2 b resulted in the quantitative elimination of (p-tolyl)N = N(ptolyl). To the best of our knowledge, this is the first example of N = N double bond formation and organic diazene elimination from a tantalum(V) bridging imido dimer. Oxidation studies of the related complex [ONO red ]TaCl 2 (4) with PhICl 2 suggest that the redox-active ligand plays the pivotal role of collecting oxidizing equivalents within the tantalum coordination sphere. The work presented herein highlights a new strategy for the design of metal complexes capable of multielectron oxidation reactions.The bridging imido complexes 2 a and 2 b were prepared via dimethyl complex 1 (Scheme 1). The methyl ligands of 1 are susceptible to protonolysis by anilines, which results in the formation of bimetallic complexes with two bridging imido ligands. As shown in Scheme 1, benzene solutions of 1 heated to reflux with two equivalents of NH 2 (p-tolyl) resulted in the formation of

show abstract

Molekül- und Kristallstruktur von Bis[chloro(μ-phenylimido)(η5-pentamethylcyclopentadienyl)tantal(IV)](Ta-Ta), [{TaCl(μ-NPh)Cp*}2]

Cited by 7 publications

References 4 publications

Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{CpTaCl(μ-PR)}2] (Cp = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)

Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{CpTaCl(μ-PR)}2] (Cp = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)

21 Organometallic chemistry of bi- and poly-nuclear complexes

Four‐Electron Oxidative Formation of Aryl Diazenes Using a Tantalum Redox‐Active Ligand Complex

Contact Info

Product

Resources

About

Molekül- und Kristallstruktur von Bis[chloro(μ-phenylimido)(η5-pentamethylcyclopentadienyl)tantal(IV)](Ta-Ta), [{TaCl(μ-NPh)Cp*}2]

Cited by 7 publications

References 4 publications

Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{Cp*TaCl(μ-PR)}2] (Cp* = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)

Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{Cp*TaCl(μ-PR)}2] (Cp* = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)

21 Organometallic chemistry of bi- and poly-nuclear complexes

Four‐Electron Oxidative Formation of Aryl Diazenes Using a Tantalum Redox‐Active Ligand Complex

Contact Info

Product

Resources

About

Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{CpTaCl(μ-PR)}2] (Cp = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)

Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{CpTaCl(μ-PR)}2] (Cp = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)