TY - JOUR

T1 - Low-valent group-13 chemistry. Theoretical investigation of the structures and relative stabilities of donor-acceptor complexes R3E-E′R′ and their isomers R2E-E′RR′

AU - Timoshkin, Alexey Y.

AU - Frenking, Gernot

PY - 2002/6/19

Y1 - 2002/6/19

N2 - The results of quantum chemical calculations at the gradient-corrected density functional theory (DFT) level with the B3LYP functional of the donor-acceptor complexes R3E-E′R′ and their isomers R2E-E′RR′, where E, E′ = B-TI and R, R′ = H, Cl, or CH3, are reported. The theoretically predicted energy differences between the donor-acceptor form R3E-E′R′ and the classical isomer R2E-E′RR′ and the bond dissociation energies of the E-E′ bonds are given. The results are discussed in order to show which factors stabilize the isomers R3E-E′R′. There is no simple correlation of the nature of the group-13 elements E, E′ and the substituents R, R′ with the stability of the complexes. The isomers R3E-E′R′ come stabilized by; π donor groups R′, while the substituents R may either be σ or; π-bonded groups. Calculations of CI3B-BR′ [R′ = CI, cyclopentadienyl (Cp), or Cp*] indicate that the Cp* group has a particularly strong effect on the complex form. The calculations show that the experimentally known complex CI3B-BCp* is the strongest bonded donor-acceptor complex of main-group elements that has been synthesized until now. The theoretically predicted B-B bond energy is Do = 50.6 kcal/mol. However, the calculations indicate that it should also be possible to isolate donor-acceptor complexes R3E-E′R′ where R′ is a σ-bonded bulky substituent. Possible candidates that are suggested for synthetic work are the borane complexes (C6F5)3B-E′R′ and tBu3B-E′R′ (E′= AI-TI) and the alane complexes CI3AI-E′R′ (E′= Ga-TI).

AB - The results of quantum chemical calculations at the gradient-corrected density functional theory (DFT) level with the B3LYP functional of the donor-acceptor complexes R3E-E′R′ and their isomers R2E-E′RR′, where E, E′ = B-TI and R, R′ = H, Cl, or CH3, are reported. The theoretically predicted energy differences between the donor-acceptor form R3E-E′R′ and the classical isomer R2E-E′RR′ and the bond dissociation energies of the E-E′ bonds are given. The results are discussed in order to show which factors stabilize the isomers R3E-E′R′. There is no simple correlation of the nature of the group-13 elements E, E′ and the substituents R, R′ with the stability of the complexes. The isomers R3E-E′R′ come stabilized by; π donor groups R′, while the substituents R may either be σ or; π-bonded groups. Calculations of CI3B-BR′ [R′ = CI, cyclopentadienyl (Cp), or Cp*] indicate that the Cp* group has a particularly strong effect on the complex form. The calculations show that the experimentally known complex CI3B-BCp* is the strongest bonded donor-acceptor complex of main-group elements that has been synthesized until now. The theoretically predicted B-B bond energy is Do = 50.6 kcal/mol. However, the calculations indicate that it should also be possible to isolate donor-acceptor complexes R3E-E′R′ where R′ is a σ-bonded bulky substituent. Possible candidates that are suggested for synthetic work are the borane complexes (C6F5)3B-E′R′ and tBu3B-E′R′ (E′= AI-TI) and the alane complexes CI3AI-E′R′ (E′= Ga-TI).

UR - http://www.scopus.com/inward/record.url?scp=0037134821&partnerID=8YFLogxK

U2 - 10.1021/ja0201754

DO - 10.1021/ja0201754

M3 - Article

C2 - 12059251

VL - 124

SP - 7240

EP - 7248

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 24

ER -