TY - JOUR
T1 - Divalent carbon(O) chemistry, part 2
T2 - Protonation and complexes with main group and transition metal lewis acids
AU - Tonner, Ralf
AU - Frenking, Gemot
PY - 2008/4/7
Y1 - 2008/4/7
N2 - Quantum-chemical calculations with DFT (BP86) and ab initio methods (MP2, SCS-MP2) were carried out for protonated and diprotonated compounds N-H + and N-(H+)2 and for the complexes N-BH 3, N-(BH3)2, N-CO2, N-(CO 2)2, N-W(CO)5, N-Ni(CO)3 and N-Ni(CO)2 where N = C(PH3), (1), C(PMe3) 2 (2), C(PPh3)2 (3), C-(PPh3)(CO) (4), C(CO)2 (5), C-(NHCH)2 (6), C(NHCMe) 2 (7) (Me2N)2C=C=C(NMe2)2 (8) and NHC (9) (NHCH = N-heterocyclic carbene, NHC Me=N-substituted N-heterocyclic carbene). Compounds 1-4 and 6-9 are very strong electron donors, and this is manifested in calculated protonation energies that reach values of up to 300 kcal mol-1 for 7 and in very high bond strengths of the donor-acceptor complexes. The electronic structure of the compounds was analyzed with charge- and energy-partitioning methods. The calculations show that the experimentally known compounds 2-5 and 8 chemically behave like molecules L2C which have two L → C donor-acceptor bonds and a carbon atom with two electron lone pairs. The behavior is not directly obvious when the linear structures of carbon suboxide and tetraaminoallenes are considered. They only come to the fore on reaction with strong electron-pair acceptors. The calculations predict that single and double protonation of 5 and 8 take place at the central carbon atom, where the negative charge increases upon subsequent protonation. The hitherto experimentally unknown carbodicarbenes 6 and 7 are predicted to be even stronger Lewis bases than the carbodiphosphoranes 1-3.
AB - Quantum-chemical calculations with DFT (BP86) and ab initio methods (MP2, SCS-MP2) were carried out for protonated and diprotonated compounds N-H + and N-(H+)2 and for the complexes N-BH 3, N-(BH3)2, N-CO2, N-(CO 2)2, N-W(CO)5, N-Ni(CO)3 and N-Ni(CO)2 where N = C(PH3), (1), C(PMe3) 2 (2), C(PPh3)2 (3), C-(PPh3)(CO) (4), C(CO)2 (5), C-(NHCH)2 (6), C(NHCMe) 2 (7) (Me2N)2C=C=C(NMe2)2 (8) and NHC (9) (NHCH = N-heterocyclic carbene, NHC Me=N-substituted N-heterocyclic carbene). Compounds 1-4 and 6-9 are very strong electron donors, and this is manifested in calculated protonation energies that reach values of up to 300 kcal mol-1 for 7 and in very high bond strengths of the donor-acceptor complexes. The electronic structure of the compounds was analyzed with charge- and energy-partitioning methods. The calculations show that the experimentally known compounds 2-5 and 8 chemically behave like molecules L2C which have two L → C donor-acceptor bonds and a carbon atom with two electron lone pairs. The behavior is not directly obvious when the linear structures of carbon suboxide and tetraaminoallenes are considered. They only come to the fore on reaction with strong electron-pair acceptors. The calculations predict that single and double protonation of 5 and 8 take place at the central carbon atom, where the negative charge increases upon subsequent protonation. The hitherto experimentally unknown carbodicarbenes 6 and 7 are predicted to be even stronger Lewis bases than the carbodiphosphoranes 1-3.
KW - Bonding analysis
KW - Carbon
KW - Density functional calculations
KW - Donor-acceptor systems
KW - Protonation
UR - http://www.scopus.com/inward/record.url?scp=47949088303&partnerID=8YFLogxK
U2 - 10.1002/chem.200701392
DO - 10.1002/chem.200701392
M3 - 文章
AN - SCOPUS:47949088303
SN - 0947-6539
VL - 14
SP - 3273
EP - 3289
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 11
ER -