Synthese und Struktur von [Cp2NbH(tBuBNtBu)], einer Verbindung mit side‐on koordiniertem Iminoboran

Dicoordinated boron compounds can no longer be considered as "exotic" species in boron chemistry: this is proved by the extensive chemistry of bis(dialkylamino)boron( 1 +) ions, alkylidene boranes, and imino boranes. The latter are characterized by high reactivity and chemical versatility. A special position is taken by amino imino boranes, whose chemistry is reported here. The presence of an amino group enhances the reactivity of imino boranes on the one hand and increases their kinetic stability on the other. New types of diamino boranes accessible via amino imino boranes often undergo intramolecular ring closure. These heterocycles are well suited to generate new types of cations of boron. Cycloaddition reactions using amino imino boranes open up a new heterocyclic chemistry of boron. The chemistry of N-functional amino imino boranes, which is still its infancy, shows much promise.

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“…Ed. Engl.27 (1988) [1603][1604][1605][1606][1607][1608][1609][1610][1611][1612][1613][1614][1615][1616][1617][1618][1619][1620][1621][1622]…”

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The Chemistry of Amino Imino Boranes

Nöth¹

1988

Angew. Chem. Int. Ed. Engl.

100

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“…The possible interconversion of 6 and 7 is involving an κ 2 -B,N-coordinated iminoborane ( 10 ) intermediate. − This is 22 kcal mol -1 lower in energy than 7 , and hence the formation of 6 from 7 is expected to be thermodynamically feasible. The barriers for rearrangement are only moderately high: 15 kcal mol -1 for interconversion of 7 to 10 ( TS 7 - 10 ) and 28 kcal mol -1 for rearrangement from 10 and 6 ( TS 10 - 6 ).…”

Section: Resultsmentioning

confidence: 99%

BN-Analogues of Vinylidene Transition Metal Complexes: The Borylnitrene Isomer

Bettinger

2007

Inorg. Chem.

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Density functional computations using the BP86 functional within the resolution-of-identity approximation and polarized triple-zeta basis sets are employed for the study of the three isoelectronic (CO)(4)FeL (L = CCH(2) (5), BNH(2) (6), NBH(2) (7)) as well as (CO)(4)Fe(NBcat) (9) (cat = catecholato) complexes. In all complexes 5-7, the ligand L prefers the equatorial position of a pseudo trigonal bipyramid. The borylnitrene complex 7 has a linear Fe-N-B arrangement; its Fe-L bond dissociation energy is similar to that of the vinylidene complex 5 and only slightly lower than that of 6. Nonetheless, 7 is less stable thermodynamically than 6 by 40 kcal mol(-1). Complexes of type 7 are expected to be reactive on the basis of the following findings: the HOMO-LUMO energy gap is small, the rearrangement from 7 to 6 via an iminoborane intermediate involves barriers of 15 and 28 kcal mol(-1), and the dissociation of a CO molecule to give (CO)(3)FeNBH(2) is only slightly endergonic (+7 kcal mol(-1) at 298.15 K). The catecholate bridge in 9 results in significant changes: the bipyramidal complex is no longer a minimum, but an isocycanato complex is obtained instead computationally.

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“…Among the numerous reactions of iminoboranes, 1,2‐additions of polar reagents across the BN multiple bond were thoroughly investigated 1. 2 In particular, hydrometallations with transition‐metal‐containing reaction partners, such as [Cp 2 Zr(H)Cl]4a,c and [Cp 2 NbH 3 ] (Cp=η 5 ‐C 5 H 5 ),4b afforded examples of transition‐metal‐bound iminoborane ligands. A coordination mode akin to that of side‐on‐bound alkynes was observed, with a varying degree of BN multiple bonding retained in the final compounds.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Characterization of Palladium and Platinum Iminoboryl Complexes

et al. 2005

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The presence of a triple bond between boron and nitrogen renders iminoboranes, XÀBNÀR, isoelectronic to alkynes, XÀCCÀR. This relationship stimulated intense experimental [1, 2] and theoretical [3] studies on these compounds. Indeed, their chemistry was extensively investigated for more than two decades, particularly in the research groups led by Paetzold [1] and Nöth. [2] Despite strong similarities in the structural properties of iminoboranes and alkynes, the polarity and relative weakness of the BN linkage [3] leads to its increased reactivity in comparison to that of the CC triple bond, and to the thermodynamic instability of iminoboranes towards cyclooligomerization.[1, 2] Low temperature, high dilution, and the presence of sterically demanding substituents on either side of the triple bond are generally necessary to hinder the otherwise favorable cyclization process and allow for the isolation of monomeric compounds.Among the numerous reactions of iminoboranes, 1,2-additions of polar reagents across the BN multiple bond were thoroughly investigated.[ [4b] afforded examples of transition-metal-bound iminoborane ligands. A coordination mode akin to that of side-on-bound alkynes was observed, with a varying degree of BN multiple bonding retained in the final compounds. Cyclodimerization of iminoboranes within the coordination sphere of different transition metals was also reported, yielding h 4 -coordinated diazadiboretidines. [1, 5a,c] [2+2] Cycloadditions of different XÀ BNÀR compounds with the short-lived complex [Cp 2 Ti= CH 2 ] yielded 1-aza-2-bora-4-titanacyclobutanes.[5b] However, in contrast to the wealth of reported transition-metal alkynyl complexes [L n M À C C À R], [6] corresponding iminoboryl compounds [L n MÀBNÀR] are unknown.We recently described the synthesis of trans-[(Cy 3 P) 2 Pt(Br){B (

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Synthese und Struktur von [Cp₂NbH(tBuBNtBu)], einer Verbindung mit side‐on koordiniertem Iminoboran

Cited by 14 publications

References 12 publications

The Chemistry of Amino Imino Boranes

The Chemistry of Amino Imino Boranes

BN-Analogues of Vinylidene Transition Metal Complexes: The Borylnitrene Isomer

Synthesis and Characterization of Palladium and Platinum Iminoboryl Complexes

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