Cooperative dinitrogen capture by a diboraanthracene/samarocene pair

Xu, Song; Essex, Laura A.; Nguyen, Joseph; Farias, Phillip; Harman, W. Dean; Evans, William J.

doi:10.1039/d1dt03220h

Cited by 12 publications

(7 citation statements)

References 41 publications

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“…55−59 Owing to their small H−L gap, 9,10-R 2 -DHDBA derivatives also undergo facile and reversible two-electron reduction to the corresponding dianions, which are isoelectronic to anthracene. 60,61 [9,10-Me 2 -DBA] 2− , for example, has a significantly smaller H−L gap (2.19 eV) than anthracene (3.56 eV, Figure 1) and has been shown to activate H 2 reversibly, 62 split water, 63 capture N 2 in conjunction with a Sm(II) center, 64 and activate or couple a number of other small molecules. 65 Furthermore, [9,10-R 2 -DBA] 2− derivatives can act as catalysts in the hydrogenation of imines, anthracene, and diphenylketene 66 and in the reduction of CO 2 to Li 2 CO 3 and CO. 67 The first diboraacene in which two CR units were replaced by isosteric and isoelectronic BL units (L = neutral donor) is the N-heterocyclic carbene (NHC)-stabilized 9,10-(IDip) 2 -DBA (IDip = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene).…”

Section: ■ Introductionmentioning

confidence: 99%

Structure and Electronics of a Series of CAAC-Stabilized Diboron-Doped Acenes from 1,4-Diboranaphthalene to 6,13-Diborapentacene

Dietz,

Arrowsmith,

Drepper

et al. 2023

J. Am. Chem. Soc.

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This combined experimental and theoretical study examines the influence of acene elongation, boron atom position, and acene substitution pattern on the structure and electronics of cyclic alkyl(amino)carbene (CAAC)-stabilized diboraacenes and presents the first syntheses of neutral diboranaphthalene (DBN) and diborapentacene (DBP). Whereas 2,3-diethyl-substituted 1,4-(CAAC)2-Et2DBN is isolated as a mixture of a planar (structurally characterized) NMR-active conformer and a presumably bent EPR-active conformer, 6,13-(CAAC)2-DBP resembles 9,10-(CAAC)2-DBA (DBA = diboraanthracene), with a highly puckered 6,13-DBP core and a typical biradical EPR signal. Both species are easily reduced to their puckered dianions. DFT calculations confirm that 6,13-(CAAC)2-DBP is only stable in its bent conformation, whereas 1,4-(CAAC)2-Et2DBN exists as both flat closed-shell and bent open-shell biradical conformers, which interchange by thermally activated ethyl and CAAC rotation/diboraacene bending processes. An in-depth computational study of the series of unsubstituted, CAAC-stabilized, symmetrically diboron-doped acenes from 1,4-(CAAC)2-DBN to 6,13-(CAAC)2-DBP was carried out. The results show interesting trends dependent on the position of the boron atoms within the acene framework as well as on the relative orientation of the CAAC ligands, which enable fine-tuning of the electronic and structural features.

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Section: ■ Introductionmentioning

confidence: 99%

Structure and Electronics of a Series of CAAC-Stabilized Diboron-Doped Acenes from 1,4-Diboranaphthalene to 6,13-Diborapentacene

Dietz,

Arrowsmith,

Drepper

et al. 2023

J. Am. Chem. Soc.

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“…The replacement of endocyclic carbon units with isosteric and isoelectronic boron fragments within aromatic compounds has been shown to deeply affect the energies of the frontier molecular orbitals (MOs) and thus the electronic properties and reactivity of the resulting boracarbocycles. − 1,4-Diborabenzene (DBB) and the related 9,10-diboraanthracence derivatives, in particular, have started to show great potential for the activation of small molecules between their two boron centers − and as highly electron-donating 6π-aromatic ligands for the stabilization of half-sandwich complexes. − Thus, the doubly cyclic alkyl(amino)carbene (CAAC)-stabilized 1,4-diborabenzene 1 (see Figure ) has been used to stabilize three- and two-legged parent half-sandwich complexes of groups 6 ( V-M ) and 8 ( VI-M ), respectively, , as well as the first examples of stable actinide arene half-sandwich complexes …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactivity of Highly Electron-Rich Zerovalent Group 10 Diborabenzene Pogo-Stick Complexes

Dietz,

Arrowsmith,

Endres

et al. 2023

J. Am. Chem. Soc.

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A cyclic alkyl(amino)carbene (CAAC)-stabilized 1,4-diborabenzene (DBB, 1) reacts with the group 10 precursor [Ni(CO) 4 ] to yield the DBB pogo-stick complex [(η 6 -DBB)Ni-(CO)] (2) as a dark-green crystalline solid. The IR-spectroscopic and X-ray crystallographic data of 2 highlight the strong π-donor properties of the DBB ligand. The reaction of 1 with [M(nbe) 2 ] (M = Pd, Pt; nbe = norbornene) yields the unique zerovalent heavier group 10 arene pogo-stick complexes [(η 6 -DBB)M(nbe)] (3-M), isolated as dark-purple and black crystalline solids, respectively. 3-Pd and 3-Pt show strong near-IR (NIR) absorptions at 835 and 904 nm, respectively. Time-dependent density functional theory (TD-DFT) calculations show that these result from the S 0 →S 1 excitation, which corresponds to a transfer of electron density from a metal d orbital aligned with the z direction (d xz or d yz ) to a d orbital located in the xy plane (d xy or d x 2 −y 2 ), with the redshift for 3-Pt resulting from the higher spin-orbit coupling (SOC). In complex 2, electron donation from the nickel center into the carbonyl 2π* orbital destabilizes the DBB•••Ni interaction, resulting in an absorption at a higher energy. Complexes 2 and 3-M react with [Fe(CO) 5 ] to yield the doubly CO-bridged M(0)→ Fe(0) (M = Ni, Pd, Pt) metal-only Lewis pairs (MOLPs) 4-M as black (M = Ni, Pt) and dark-turquoise (M = Pd) crystalline solids. Furthermore, 3-Pt undergoes oxidative Sn−H addition with Ph 3 SnH to yield the corresponding Pt(II) stannyl hydride, [(η 6 -DBB)PtH(SnPh 3 )] (5).

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“…Within the field of main group chemistry, compounds such as frustrated Lewis pairs − or poly-Lewis acids (PLAs) containing main group elements as reactive sites–including octet compliant metallacyclo-compounds − along with systems of low-coordinate, electron-deficient Lewis centers anchored to organic backbones − –have been of special interest in the last decades, since most main group (semi-)metals are more abundant and the utilized compounds are often less toxic than analogous transition metal-based molecules. PLAs containing main group elements can be used in small molecule recognition, ,,,− anion sensing, ,,,,,,,− or in catalysis. ,− ,, This is why we focus on PLAs containing group 13 elements such as aluminum, boron, or gallium as active sites.…”

Section: Introductionmentioning

confidence: 99%

Hydroalumination of 1,8-Diethynylanthracenes–Al-based Bis-Lewis-Acids and their Isomerization and Complexation Behavior

et al. 2022

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Substituted anthracene derivatives−monomers and photodimers−bearing alkynyl units were treated with the bulky aluminum hydride [(SiMe 3 ) 2 HC] 2 AlH in hydroalumination reactions in order to investigate the influence of the substituents on the spacing between the alkynyl units. While 1,8bis[(trimethylsilyl)ethynyl]anthracene only resulted in the mono-hydroalumination product, 1,8-diethynylanthracene and its photo-dimer afforded the products of twofold hydroalumination. In the case of 1,8-diethynylanthracene, the product underwent a cis/trans-isomerization of one of the newly formed C�C bonds. This process was examined via quantum-chemical calculations. The twofold hydroaluminated syn-photo-dimer of 1,8-diethynylanthracene was treated with various donor molecules to gain insights into its host−guest chemistry.

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Cooperative dinitrogen capture by a diboraanthracene/samarocene pair

Abstract: The combination of a boron Lewis acid and a decamethylsamarocene, specifically 9,10-Me2-9,10-diboraanthracene with (C5Me5)2SmII(THF)2, in toluene leads to cooperative reductive capture of N2. The product crystallizes as the salt, [(C5Me5)2SmIII(THF)2][(C5Me5)2SmIII(η2-N2B2C14H14)],...

Cited by 12 publications

References 41 publications

Structure and Electronics of a Series of CAAC-Stabilized Diboron-Doped Acenes from 1,4-Diboranaphthalene to 6,13-Diborapentacene

Structure and Electronics of a Series of CAAC-Stabilized Diboron-Doped Acenes from 1,4-Diboranaphthalene to 6,13-Diborapentacene

Synthesis and Reactivity of Highly Electron-Rich Zerovalent Group 10 Diborabenzene Pogo-Stick Complexes

Hydroalumination of 1,8-Diethynylanthracenes–Al-based Bis-Lewis-Acids and their Isomerization and Complexation Behavior

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