A quadruply-bonded [Cr2(guanidinate)4]4− tetraanion

Haywood, Joanna; Stokes, Francesca A.; Less, Robert J.; McPartlin, Mary; Wheatley, Andrew E. H.; Wright, Dominic S.

doi:10.1039/c1cc10194c

Cited by 11 publications

(3 citation statements)

References 25 publications

(6 reference statements)

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“…The alkyl exchange reactions in this work also bear resemblance to salt metathesis-like reactions involving cyclopentadienyl anion elimination from polar metallocenes. These include the reaction of [{Cp* 2 U} 2 (μ-η 6 :η 6 -C 6 H 6 )] with MX (M = K, X = N(SiMe 3 ) 2 , OC 6 H 2 (CMe 3 ) 2 -2,6-Me-4; M = Li, X = CH(SiMe 3 ) 2 , i PrNCMeN i Pr) to form [{Cp*XU} 2 (μ-η 6 :η 6 -C 6 H 6 )], reaction of [MnCp 2 ] with LiC 2 Ph in THF to provide 0.5 [{CpMn(μ-C 2 Ph)(THF)} 2 ], reaction of [MnCp 2 ] with 1 or 3 equiv of Li(hpp) to afford 0.5 [{CpMn(hpp)} 2 ] or [{LiMn(hpp) 3 } 2 ], reaction of [VCp 2 ] with 2 equiv of Li(hpp) to give 0.25 [{V 2 (hpp) 4 }Li(μ-Cp)Li(μ-Cp)Li{V 2 (hpp) 4 }][CpLi(μ-Cp)LiCp], and reaction of [CrCp 2 ] with 2 equiv of Li(MeNCHNMe) to yield 0.5 [Cr 2 (MeNCHNMe) 4 ] …”

Section: Results and Discussionmentioning

confidence: 99%

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

et al. 2013

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Reaction of [(XA2)UCl3{K(dme)3}] (XA2 = 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene) with 2 equiv of ((trimethylsilyl)methyl)lithium or neopentyllithium afforded red-orange [(XA2)U(CH2SiMe3)2] (1) and dark red [(XA2)U(CH2CMe3)2] (2), respectively. Reaction of 1 with an additional 1 equiv of LiCH2SiMe3 in THF yielded yellow [Li(THF) x ][(XA2)U(CH2SiMe3)3] (3), and reaction of [(XA2)UCl3{K(dme)3}] with 3 equiv of methyllithium in dme afforded yellow [Li(dme)3][(XA2)UMe3] (4). Reaction of 1 with 2.1 equiv of LiCH2CMe3 in benzene resulted in rapid conversion to 2, with release of 2 equiv of LiCH2SiMe3. Similarly, reaction of 1 with 3.3 equiv of MeLi in THF provided 4 as the [Li(THF) x ]+ salt, accompanied by 2 equiv of LiCH2SiMe3. These unusual alkyl exchange reactions resemble salt metathesis reactions, but with elimination of an alkyllithium instead of a lithium halide. Addition of a large excess of LiCH2SiMe3 to 2 or 4 did not generate detectable amounts of 1 by NMR spectroscopy, suggesting that the equilibrium in these reactions lies far to the side of complexes 2 and 4. In contrast, the reaction of [(XA2)Th(CH2SiMe3)2] (1-Th) with 2.2 equiv of LiCH2CMe3 yielded an approximate 1:1:3:1 mixture of [(XA2)Th(CH2CMe3)2] (2-Th), [(XA2)Th(CH2SiMe3)(CH2CMe3)] (5-Th), LiCH2SiMe3, and LiCH2CMe3.

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Section: Results and Discussionmentioning

confidence: 99%

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

et al. 2013

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“…While Cotton is well known for his group's work with homobimetallic complexes having the tetragonal paddlewheel geometry, the earliest of these compounds containing first row transition metals dates as far back as 1844. 22,23 Since then, tetragonal paddlewheel complexes containing multiple bonds between vanadium, [24][25][26][27][28][29][30] iron, 31,32 chromium, [33][34][35] cobalt, [36][37][38][39] and nickel [40][41][42] atoms have been synthesized. Of all the first row transition metals, chromium is the most prevalent metal found in metal-metal bonded species, likely owing to factors such as size and an intermediate electron count, allowing electrons to sufficiently populate metal-metal bonding orbitals without accessing orbitals with metal-metal anti-bonding character.…”

Section: Introductionmentioning

confidence: 99%

Metal–metal multiple bonding in C3-symmetric bimetallic complexes of the first row transition metals

2014

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Metal-metal multiple bonds have been an intense area of focus in inorganic chemistry for many decades as a result of their fundamentally interesting bonding properties, as well as their potential applications in multielectron transfer and small molecule activation processes. Much of what is known in this field revolves around 2nd and 3rd row transition metals, with fundamental knowledge lacking in the area of bonds between elements of the first transition series. The smaller size and tendency of first row ions to adopt high-spin electron configurations weaken metal-metal interactions and serve to complicate the interpretation of the electronic structure and bonding in bimetallic species containing first row transition metals. Furthermore, traditional tetragonal "paddlewheel" complexes dominate the metal-metal multiple bond literature, and only recently have researchers begun to take advantage of the weaker ligand field in three-fold symmetric bimetallic complexes to encourage more favourable metal-metal bonding interactions. In the past 5 years, several research groups have exploited three-fold symmetric frameworks to investigate new trends in metal-metal bonding involving the first row transition metals. This feature article serves to highlight recent achievements in this area and to use C3-symmetric systems as a model to better understand the fundamental aspects of multiple bonds featuring first row transition metals.

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“…28 The synthesis, characterisation, and optical properties of the compounds trans- 29 The reaction of chromocene, Cp 2 Cr, with dilithiated 2,3-diphenylguanidine [(PhNH) 2 CQNHQL 2 H 3 ] was reported to from the novel, quadruply-bonded tetraanion [Cr 2 (L 2 H) 4 ] 4À . 30 Lowcoordinate phosphorus compounds (Me 3 Si) 2 N-PQNSiMe 3 , (Me 3 Si) 2 N-P(QS)QN t Bu and (Me 3 Si) 2 N-P(QNSiMe 3 ) 2 were reacted with ( i PrO) 3 MRM(O i Pr) 3 (M = Mo, W) to produce four-and five-membered metallacycles with intact endocyclic or exocyclic MRM triple bonds. 1…”

Section: Multiple Metal-metal Bonded Complexesmentioning

confidence: 99%

Chromium, molybdenum and tungsten

Holder

2012

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

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This chapter reviews the literature reported during 2011 on some important advances in the areas of catalysis, bioinorganic, and organometallic chemistry for the chromium triad. Research highlights for each metal during the year are also given. HighlightsThe highlights include: (I) The first four-membered planar metallacycles, containing an MRM triple bond, obtained in reaction with (Me 3 Si) 2 N-PQNSiMe 3 ; 1 (II) chromium(III)-containing species used in reducing cholesterol, triglycerides, and carbohydrate, and affecting lipid metabolism; 2-4 (III) a study used to evaluate the effect chromium picolinate on swine growth performance, meat quality, and protein deposition in skeletal muscle; 5 (IV) a report based on the structure, photophysics, electrochemistry, DFT calculation, and in vitro antioxidant activity of coumarin Schiff base complexes of group 6 metal carbonyls; 6 (V) a new class of photochemically activated CO-releasing molecules; 7 (VI) a new coordination polymer, H[(Ce(H 2 O) 5 ) 2 -(Ce(pdc) 2 (H 2 O) 4 )(Ce(pdc) 3 )(PW 12 O 40 )]Á2H 2 O, that was found to be active for photocatalytic H 2 evolution under UV irradiation.

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A quadruply-bonded [Cr2(guanidinate)4]4− tetraanion

Abstract: The reaction of chromocene, Cp(2)Cr, with dilithiated 2,3-diphenylguanidine [(PhNH)(2)C=NH = L(2)H(3)] gives the novel, quadruply-bonded tetraanion [Cr(2)(L(2)H)(4)](4-).

Cited by 11 publications

References 25 publications

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

Metal–metal multiple bonding in C3-symmetric bimetallic complexes of the first row transition metals

Chromium, molybdenum and tungsten

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