Transition‐Metal‐Mediated Cleavage of a SiSi Double Bond

Hickox, Hunter P.; Wang, Yu‐Zhong; Xie, Yaoming; Chen, Mingwei; Wei, Pingrong; Schaefer, Henry F.; Robinson, Gregory H.

doi:10.1002/ange.201503069

Cited by 11 publications

(2 citation statements)

References 80 publications

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“…227 On the other hand, the reaction with iron pentacarbonyl Fe(CO) 5 affords the related donor−acceptorstabilized dark purple iron complex 706b in high yield. 678 The solid-state structures exposed trigonal planar coordination spheres around the tricoordinate Si(0) atoms with slightly shortened SiSi double bond lengths of 2.206( 12 611 Interestingly, the reaction of the two-coordinate disilene derivative 572 with the organic azide DippN 3 provides the first NHC-stabilized siladiimide complex 59 in 35% yield as already mentioned above. 579 In the course of the past decade, the parent silylene (H 2 Si:) and dichlorosilylene (Cl 2 Si:) have been successfully trapped with the aid of donor(−acceptor)-stabilization and isolated as shown above (cf., section 2.4.2.3).…”

Section: Chemical Reviewsmentioning

confidence: 69%

NHCs in Main Group Chemistry

et al. 2018

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Since the discovery of the first stable N-heterocyclic carbene (NHC) in the beginning of the 1990s, these divalent carbon species have become a common and available class of compounds, which have found numerous applications in academic and industrial research. Their important role as two-electron donor ligands, especially in transition metal chemistry and catalysis, is difficult to overestimate. In the past decade, there has been tremendous research attention given to the chemistry of low-coordinate main group element compounds. Significant progress has been achieved in stabilization and isolation of such species as Lewis acid/base adducts with highly tunable NHC ligands. This has allowed investigation of numerous novel types of compounds with unique electronic structures and opened new opportunities in the rational design of novel organic catalysts and materials. This Review gives a general overview of this research, basic synthetic approaches, key features of NHC-main group element adducts, and might be useful for the broad research community.

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Section: Chemical Reviewsmentioning

confidence: 69%

NHCs in Main Group Chemistry

et al. 2018

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“…Reaction with an excess of Fe(CO) 5 afforded a bimetallic Fe 2 (CO) 6 complex with CO insertion into the Si−Si bond. 258 Cleavage of the Si−Si bond was also observed upon treatment of 150 with equiv of pyridinium chloride, which gave the Fe(CO) 3 complex 151 with two silylene (silylidene) ligands [(IDipp)SiHCl] residing in the axial positions of a distorted trigonal bipyramid (Scheme 43). 259 While the chlorosilylene ligand in 151 was generated by HCl transfer to the silicon atoms, related isolable silicon(II) NHC adducts of the type [(IDipp)SiX 2 ] (154, X = Cl; 155, X = Br) had been prepared before independently by the groups of Filippou, Roesky, and Stalke by reduction of the silicon(IV) chloride and bromide precursors 152 and 153, respectively (Scheme 44).…”

Section: Siliconmentioning

confidence: 99%

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

2019

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N-Heterocyclic carbenes (NHC) are nowadays ubiquitous and indispensable in many research fields, and it is not possible to imagine modern transition metal and main group element chemistry without the plethora of available NHCs with tailor-made electronic and steric properties. While their suitability to act as strong ligands toward transition metals has led to numerous applications of NHC complexes in homogeneous catalysis, their strong σ-donating and adaptable π-accepting abilities have also contributed to an impressive vitalization of main group chemistry with the isolation and characterization of NHC adducts of almost any element. Formally, NHC coordination to Lewis acids affords a transfer of nucleophilicity from the carbene carbon atom to the attached exocyclic moiety, and low-valent and lowcoordinate adducts of the p-block elements with available lone pairs and/or polarized carbon-element π-bonds are able to act themselves as Lewis basic donor ligands toward transition metals. Accordingly, the availability of a large number of novel NHC adducts has not only produced new varieties of already existing ligand classes but has also allowed establishment of numerous complexes with unusual and often unprecedented element−metal bonds. This review aims at summarizing this development comprehensively and covers the usage of N-heterocyclic carbene adducts of the p-block elements as ligands in transition metal chemistry.

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Cleavage of a P=P Double Bond Mediated by N‐Heterocyclic Carbenes

et al. 2017

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The reaction of the bulky diphosphenes (Rind)P=P(Rind) (1; Rind=1,1,3,3,5,5,7,7‐octa‐R‐substituted s‐hydrindacen‐4‐yl) with two molecules of N‐heterocyclic carbene (NHC; 1,3,4,5‐tetramethylimidazol‐2‐ylidene) resulted in the quantitative formation of the NHC‐bound phosphinidenes NHC→P(Rind) (2), along with the cleavage of the P=P double bond. The reaction times are dependent on the steric size of the Rind groups (11 days for 2 a (R=Et) and 2 h for 2 b (R=Et, Me) at room temperature). The mechanism for the double bond‐breaking is proposed to proceed via the formation of the NHC‐coordinated, highly polarized diphospehenes 3 as an intermediate. Approach of a second NHC to 3 induces P−P bond cleavage and P−C bond formation, which proceeds through a transition state with a large negative Gibbs energy change to afford the two molecules of 2, thus being the rate‐determining step of the overall reaction with the activation barriers of 80.4 for 2 a and 29.1 kJ mol−1 for 2 b.

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Transition‐Metal‐Mediated Cleavage of a SiSi Double Bond

Cited by 11 publications

References 80 publications

NHCs in Main Group Chemistry

NHCs in Main Group Chemistry

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

Cleavage of a P=P Double Bond Mediated by N‐Heterocyclic Carbenes

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