Synthesis and characterization of an infinite sheet of metal–alkyl bonds: unfolding the elusive structure of an unsolvated alkali-metal trisalkylmagnesiate

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To advance the catalytic applications of s-block mixed-metal complexes, sodium magnesiate [NaMg(CH SiMe ) ] (1) is reported as an efficient precatalyst for the guanylation of a variety of anilines and secondary amines with carbodiimides. First examples of hydrophosphination of carbodiimides by using a Mg catalyst are also described. The catalytic ability of the mixed-metal system is much greater than that of its homometallic components [NaCH SiMe ] and [Mg(CH SiMe ) ]. Stoichiometric studies suggest that magnesiate amido and guanidinate complexes are intermediates in these catalytic routes. Reactivity and kinetic studies imply that these guanylation reactions occur via (tris)amide intermediates that react with carbodiiimides in insertion steps. The rate law for the guanylation of N,N'-diisopropylcarbodiimide with 4-tert-butylaniline catalyzed by 1 is first order with respect to [amine], [carbodiimide], and [catalyst], and the reaction shows a large kinetic isotopic effect, which is consistent with an amine-assisted rate-determining carbodiimide insertion transition state. Studies to assess the effect of sodium in these transformations denote a secondary role with little involvement in the catalytic cycle.

Section: Resultsmentioning

confidence: 99%

“…[6,19,37] LiCH 2 SiMe 3 ,a mines, phosphines, and carbodiimides were purchased from Sigma-Aldrich and used as received. Hexane, benzene, and THF were dried by heating to reflux over sodium benzophenone ketyl and distilled under nitrogen or were passed through ac olumn of activated alumina (Innovative Te ch.…”

Section: General Considerationsmentioning

confidence: 99%

Structural and Mechanistic Insights into s‐Block Bimetallic Catalysis: Sodium Magnesiate‐Catalyzed Guanylation of Amines

Tullio

Hernán‐Gómez

Livingstone

et al. 2016

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“…Inspection of the sodium-carbon distances within 1 (Table 1) shows that there is no significant variation that would define a specific molecular unit. Thus all three Na-C distances in 1 lie within relatively small range [2.653 (4) 13 This ring-fused structure contrasts with those found for the monometallic components of 1, which are also highly aggregated but display polymeric chain arrangements made up in each case by association of {Mn2(CH2SiMe3)2} dimers 19 or {Na(CH2SiMe3)}4 tetramers. In all figures hydrogen atoms have been omitted for clarity and ellipsoids are drawn in 50% probability.…”

Section: Solid-state Structuresmentioning

confidence: 58%

“…12 Starting to fill this gap of knowledge and building on our previous work on main-group heterobimetallic (ate) compounds, 13 here we extend our studies to alkali-metal manganate chemistry. By systematically probing the co-complexation reactions of [MCH2SiMe3] (M = Na or K) with [Mn(CH2SiMe3)2] in a variety of solvent combinations, containing in some cases Lewis donors of different hapticities and coordinative properties, a new family of tris(alkyl) alkalimetal manganates is presented.…”

Section: Introductionmentioning

confidence: 99%

Structural and Magnetic Diversity in Alkali‐Metal Manganate Chemistry: Evaluating Donor and Alkali‐Metal Effects in Co‐complexation Processes

Uzelac

Borilović

Amores

et al. 2016

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This version is available at https://strathprints.strath.ac.uk/55900/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. FULL PAPER Structural and magnetic diversity in alkali-metal manganate chemistry: Evaluating donor and alkali-metal effects in cocomplexation processesMarina Uzelac, [a] Ivana Borilovic, [b] Marco Amores, [a] Thomas Cadenbach, [a], [c] Alan R. Kennedy, [a] Guillem Aromí,* [b] and Eva Hevia* [a] Abstract: By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M= Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors [bidentate TMEDA, 1,4-dioxane and 1,4-diazabicyclo[2,2,2] octane (DABCO)] has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali-metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray crystallographic, SQUID magnetization measurements and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2MMn (CH2SiMe3) (7)). Interestingly, the identity of the alkali-metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2(CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from -metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers exhibit antiferromagnetic coupling of their S= 5/2 moments with varying intensity depending on the nature of the exchange pathways.

“…This ate was first developed by our group [16] and has already shown great promise as an efficient precatalyst in hydroaminationr eactions of isocyanates and carbodiimides. This ate was first developed by our group [16] and has already shown great promise as an efficient precatalyst in hydroaminationr eactions of isocyanates and carbodiimides.…”

Section: Resultsmentioning

confidence: 99%

Molecular Manipulations of a Utility Nitrogen–Heterocyclic Carbene by Sodium Magnesiate Complexes and Transmetallation Chemistry with Gold Complexes

Hernán‐Gómez

Uzelac

Baillie

et al. 2018

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Expanding the scope and applications of anionic N-heterocyclic carbenes (NHCs), a novel series of magnesium NHC complexes is reported using a mixed sodium-magnesium approach. Sequential reactivity of classical imidazol- 2-ylidene carbene IPr with NaR and MgR (R=CH SiMe ) affords [(THF) Na(μ-IPr )MgR (THF)] (2) [IPr =:C{[N(2,6-iPr C H )] CHC] containing an anionic NHC ligand, whereas surprisingly sodium magnesiate [NaMgR ] fails to deprotonate IPr affording instead the redistribution coordination adduct [IPr Na MgR ] (1). Compound 2 undergoes selective C2-methylation when treated with MeOTf furnishing novel abnormal NHC complex [{aIPr MgR } ] (3). Dissolving 3 in THF led to the dissociation of this complex into MgR and aIPr with the latter isomerizing to the olefinic NHC IPr=CH . The ability of 2 and 3 to transfer their anionic and abnormal NHC ligands, respectively to Au metal fragments has been investigated allowing the isolation and structural characterization of [RAu(μ-IPr )MgR(THF) ] (4) and [aIPr AuR] (5) respectively. In both cases transfer of an alkyl R group is observed. However while 3 can also transfer its abnormal NHC ligand to give 5, in 4 the anionic NHC still remains coordinated to Mg via its C4 position, whereas the {AuR} fragment occupies the C2 position previously filled by a donor-solvated {Na(THF) } cation.