Geometry, stability and aromaticity of β-diketiminate-coordinated alkaline-earth compounds

Li, Yuanyuan; Chen, Haohua; Qu, Lingbo; Bai, Ruopeng; Lan, Yu

doi:10.1016/j.cclet.2019.06.001

“…The singlet at −48.7 ppm in the 31 P NMR spectrum is slightly down‐field shifted compared to 4 . The 1 H and 13 C NMR spectra of 7 prove that addition of EtNCO breaks the conjugated electronic system of the C 3 N 2 Ga ring in 5 , [38] since the γ‐CH (5.36 ppm) and γ‐C (70.6 ppm) resonances are significantly up‐field shifted compared to those of 5 . The 31 P NMR spectrum displays a singlet at −70.7 ppm.…”

Section: Resultsmentioning

confidence: 85%

Synthesis and Reactivity of Heteroleptic Ga‐P‐C Allyl Cation Analogues

Li

¹

,

Wölper

²

,

Haberhauer

³

et al. 2020

Angew. Chem. Int. Ed.

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Oxidative addition of cyclic alkyl(amino)carbenecoordinated phosphinidenes (Me cAAC)PX to LGa affords gallium-coordinated phosphinidenes LGa(X)-P(Me cAAC) (L = HC[C(Me)N(2,6-i-Pr 2 C 6 H 3)] 2 ;X = Cl 1,B r2), which react with NaBAr F 4 and LiAl(OR F) 4 to [LGaP(Me cAAC)][An] (An = B(C 6 H 3 (CF 3) 2) 4 3,B (C 6 F 5) 4 4,A l(OC(CF 3) 3) 4 5). The cations in 3-5 show substantial Ga À Pd ouble bond character and represent heteronuclear analogues of allyl cations according to quantum chemical calculations.The reaction of 4 with 4dimethylaminopyridine (dmap) to adduct 6 confirms the strong electrophilic nature of the gallium center,w hereas 5 reacts with ethyl isocyanate with C À Cbond formation to the g-Ca tom of the b-diketiminate ligand and formation of compound 7. Scheme 1. Structurallyc haracterized cations A-F (E:R= I, H, Me, Et); F:R= Si(i-Pr)[CH(SiMe 3) 2 ] 2); A, D:E= Si, Ge) and resonance structures of allyl and heavier homologues.

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“…[37] The 1 HNMR spectrum of 6 shows resonances of the bdiketiminate ligand, the carbene and dmap.T he singlet at 5.42 ppm (g-CH)isup-field shifted compared to that of 4,and the resonance of the NMe 2 group is displayed at 3.15 ppm. Thesinglet at À48.7 ppm in the 31 PNMR spectrum is slightly down-field shifted compared to 4.T he 1 Ha nd 13 CNMR spectra of 7 prove that addition of EtNCO breaks the conjugated electronic system of the C 3 N 2 Ga ring in 5, [38] since the g-CH (5.36 ppm) and g-C (70.6 ppm) resonances are significantly up-field shifted compared to those of 5.T he 31 PNMR spectrum displays asinglet at À70.7 ppm.…”

Section: Angewandte Chemiementioning

confidence: 82%

Synthesis and Reactivity of Heteroleptic Ga‐P‐C Allyl Cation Analogues

Li

¹

,

Wölper

²

,

Haberhauer

³

et al. 2020

Angewandte Chemie

9

0

View full text Add to dashboard Cite

Oxidative addition of cyclic alkyl(amino)carbenecoordinated phosphinidenes (Me cAAC)PX to LGa affords gallium-coordinated phosphinidenes LGa(X)-P(Me cAAC) (L = HC[C(Me)N(2,6-i-Pr 2 C 6 H 3)] 2 ;X = Cl 1,B r2), which react with NaBAr F 4 and LiAl(OR F) 4 to [LGaP(Me cAAC)][An] (An = B(C 6 H 3 (CF 3) 2) 4 3,B (C 6 F 5) 4 4,A l(OC(CF 3) 3) 4 5). The cations in 3-5 show substantial Ga À Pd ouble bond character and represent heteronuclear analogues of allyl cations according to quantum chemical calculations.The reaction of 4 with 4dimethylaminopyridine (dmap) to adduct 6 confirms the strong electrophilic nature of the gallium center,w hereas 5 reacts with ethyl isocyanate with C À Cbond formation to the g-Ca tom of the b-diketiminate ligand and formation of compound 7. Scheme 1. Structurallyc haracterized cations A-F (E:R= I, H, Me, Et); F:R= Si(i-Pr)[CH(SiMe 3) 2 ] 2); A, D:E= Si, Ge) and resonance structures of allyl and heavier homologues.

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“…Moreover, we speculated that the change of geometry may lead to the weakening of carborane's aromaticity. 96 Therefore, the nucleus-independent chemical shift 97 (NICS) is calculated to quantitatively evaluate the aromaticity of the o-carborane moiety in the key reductive elimination transition states. Because the carborane is a dimensional cage structure, the position of the virtual ghost atom is put at the geometric center of the conjugated carborane sphere (see ESI † Part 5).…”

Section: Regioselectivitymentioning

confidence: 99%