Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization

The desymmetrization of the cyclic (alkyl)­(amino)­carbene-supported diboracumulene B₂(cAAC^Me)₂ (cAAC^Me = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe^Me (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp–sp² diboron compound B₂(cAAC^Me)₂(IMe^Me), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp²–sp² diboron compounds by adduct formation with IMe^Me and CO, respectively. Furthermore, B₂(cAAC^Me)₂(IMe^Me) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C–H activation and facile twofold hydrogenation, the latter resulting in B–B bond cleavage and the formation of the mixed-base parent borylene (cAAC^Me)­(IMe^Me)­BH

Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization

The desymmetrization of the cyclic (alkyl)­(amino)­carbene-supported diboracumulene B₂(cAAC^Me)₂ (cAAC^Me = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe^Me (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp–sp² diboron compound B₂(cAAC^Me)₂(IMe^Me), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp²–sp² diboron compounds by adduct formation with IMe^Me and CO, respectively. Furthermore, B₂(cAAC^Me)₂(IMe^Me) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C–H activation and facile twofold hydrogenation, the latter resulting in B–B bond cleavage and the formation of the mixed-base parent borylene (cAAC^Me)­(IMe^Me)­BH

Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization

The desymmetrization of the cyclic (alkyl)­(amino)­carbene-supported diboracumulene B₂(cAAC^Me)₂ (cAAC^Me = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe^Me (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp–sp² diboron compound B₂(cAAC^Me)₂(IMe^Me), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp²–sp² diboron compounds by adduct formation with IMe^Me and CO, respectively. Furthermore, B₂(cAAC^Me)₂(IMe^Me) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C–H activation and facile twofold hydrogenation, the latter resulting in B–B bond cleavage and the formation of the mixed-base parent borylene (cAAC^Me)­(IMe^Me)­BH

Diboran(4)yl Platinum(II) Complexes

The platinum diboran(4)­yl complexes <b>1</b>–<b>3</b> have been prepared by the selective oxidative addition of one B–Hal bond in aryl-substituted diboranes(4) Hal₂B₂Ar₂ (Hal = Cl, Ar = mes, dur; Hal = I, Ar = mes). Because of the electron deficiency of the remote B2 atom, all species show a rare dative Pt–B bonding interaction, whose magnitude is strongly dependent on the nature of the halide substituent

Synthesis and Structure of a Carbene-Stabilized Boraallene Coordinated to Rhodium

Reaction of the (B,C-η²)-1-aza-2-borabutatriene rhodium complex <b>1</b> with 1,3-dimethylimidazol-2-ylidene) (<i>I</i>Me, <b>2</b>) afforded the N-heterocyclic carbene-stabilized (C,C-η²)-1-boraallene rhodium complex <b>3</b>, which has been characterized in solution and by X-ray crystallography. Density functional theory calculations were carried out to elucidate the observed base-induced B–C to C–C coordination mode shift, which suggested that the latter is 25 kJ/mol lower in energy

Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization

The desymmetrization of the cyclic (alkyl)­(amino)­carbene-supported diboracumulene B₂(cAAC^Me)₂ (cAAC^Me = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe^Me (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp–sp² diboron compound B₂(cAAC^Me)₂(IMe^Me), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp²–sp² diboron compounds by adduct formation with IMe^Me and CO, respectively. Furthermore, B₂(cAAC^Me)₂(IMe^Me) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C–H activation and facile twofold hydrogenation, the latter resulting in B–B bond cleavage and the formation of the mixed-base parent borylene (cAAC^Me)­(IMe^Me)­BH

Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization

The desymmetrization of the cyclic (alkyl)­(amino)­carbene-supported diboracumulene B₂(cAAC^Me)₂ (cAAC^Me = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe^Me (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp–sp² diboron compound B₂(cAAC^Me)₂(IMe^Me), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp²–sp² diboron compounds by adduct formation with IMe^Me and CO, respectively. Furthermore, B₂(cAAC^Me)₂(IMe^Me) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C–H activation and facile twofold hydrogenation, the latter resulting in B–B bond cleavage and the formation of the mixed-base parent borylene (cAAC^Me)­(IMe^Me)­BH

Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization

The desymmetrization of the cyclic (alkyl)­(amino)­carbene-supported diboracumulene B₂(cAAC^Me)₂ (cAAC^Me = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe^Me (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp–sp² diboron compound B₂(cAAC^Me)₂(IMe^Me), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp²–sp² diboron compounds by adduct formation with IMe^Me and CO, respectively. Furthermore, B₂(cAAC^Me)₂(IMe^Me) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C–H activation and facile twofold hydrogenation, the latter resulting in B–B bond cleavage and the formation of the mixed-base parent borylene (cAAC^Me)­(IMe^Me)­BH

Diboran(4)yl Platinum(II) Complexes

The platinum diboran(4)­yl complexes <b>1</b>–<b>3</b> have been prepared by the selective oxidative addition of one B–Hal bond in aryl-substituted diboranes(4) Hal₂B₂Ar₂ (Hal = Cl, Ar = mes, dur; Hal = I, Ar = mes). Because of the electron deficiency of the remote B2 atom, all species show a rare dative Pt–B bonding interaction, whose magnitude is strongly dependent on the nature of the halide substituent

Synthesis of the First Heteroaryl-Substituted Boryl Complexes: Strong Stabilizing Effects of Boron–Aryl π‑Conjugation

The first examples of heteroarylboryl complexes were prepared and have been found to be unreactive toward a range of strong reductants, strong Lewis bases, and halide-abstraction reagents. The inertness of the complexes is attributed to strong π-conjugation between the π-basic heteroaryl groups and the π-acidic boron atom. This hypothesis is supported by comparison of the structural and spectroscopic properties of the heteroarylboryl complexes with analogous previously reported homoarylboryl complexes, with the former showing greater coplanarity of the aryl ring with the boron atom and much less facile reactivity