TY - JOUR
T1 - Divalent carbon(0) chemistry, part 1
T2 - Parent compounds
AU - Tonner, Ralf
AU - Frenking, Gernot
PY - 2008/4/7
Y1 - 2008/4/7
N2 - Quantum-chemical calculations with DFT (BP86) and ab initio methods [MP2, SCS-MP2, CCSD(T)] have been carried out for the molecules C(PH,), (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), where NHC = N-heterocyclic carbene and NHCMe = N-methyl-substituted NHC. The electronic structure in 1-9 was analyzed with charge- and energy-partitioning methods. The results show that the bonding situations in L2C compounds 1-8 can be interpreted in terms of donor-acceptor interactions between closed-shell ligands L and a carbon atom which has two lone-pair orbitais L→C←L. This holds particularly for the carbodiphosphoranes 1-3 where L = PR3, which therefore are classified as divalent carbon(O) compounds. The NBO analysis suggests that the best Lewis structures for the carbodicarbenes 6 and 7 where L is a NHC ligand have C=C=C double bonds as in the tetraaminoallene 8. However, the Lewis structures of 6-8, in which two lone-pair orbitals at the central carbon atom are enforced, have only a slightly higher residual density. Visual inspection of the frontier orbitals of the latter species reveals their pronounced lone-pair character, which suggests that even the quasi-linear tetraaminoallene 8 is a "masked" divalent carbon(0) compound. This explains the very shallow bending potential of 8. The same conclusion is drawn for phosphoranylketene 4 and for carbon suboxide (5), which according to the bonding analysis have hidden double-lone-pair character. The AIM analysis and the EDA calculations support the assignment of carbodiphosphoranes as divalent carbon(0) compounds, while NHC 9 is characterized as a divalent carbon(II) compound. The L→C(1D) donor-acceptor bonds are roughly twice as strong as the respective L→ BH3 bond.
AB - Quantum-chemical calculations with DFT (BP86) and ab initio methods [MP2, SCS-MP2, CCSD(T)] have been carried out for the molecules C(PH,), (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), where NHC = N-heterocyclic carbene and NHCMe = N-methyl-substituted NHC. The electronic structure in 1-9 was analyzed with charge- and energy-partitioning methods. The results show that the bonding situations in L2C compounds 1-8 can be interpreted in terms of donor-acceptor interactions between closed-shell ligands L and a carbon atom which has two lone-pair orbitais L→C←L. This holds particularly for the carbodiphosphoranes 1-3 where L = PR3, which therefore are classified as divalent carbon(O) compounds. The NBO analysis suggests that the best Lewis structures for the carbodicarbenes 6 and 7 where L is a NHC ligand have C=C=C double bonds as in the tetraaminoallene 8. However, the Lewis structures of 6-8, in which two lone-pair orbitals at the central carbon atom are enforced, have only a slightly higher residual density. Visual inspection of the frontier orbitals of the latter species reveals their pronounced lone-pair character, which suggests that even the quasi-linear tetraaminoallene 8 is a "masked" divalent carbon(0) compound. This explains the very shallow bending potential of 8. The same conclusion is drawn for phosphoranylketene 4 and for carbon suboxide (5), which according to the bonding analysis have hidden double-lone-pair character. The AIM analysis and the EDA calculations support the assignment of carbodiphosphoranes as divalent carbon(0) compounds, while NHC 9 is characterized as a divalent carbon(II) compound. The L→C(1D) donor-acceptor bonds are roughly twice as strong as the respective L→ BH3 bond.
KW - Bonding analysis
KW - Carbon
KW - Carbon complexes
KW - Density functional calculations
KW - Donoracceptor systems
UR - http://www.scopus.com/inward/record.url?scp=47949093678&partnerID=8YFLogxK
U2 - 10.1002/chem.200701390
DO - 10.1002/chem.200701390
M3 - 文章
AN - SCOPUS:47949093678
SN - 0947-6539
VL - 14
SP - 3260
EP - 3272
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 11
ER -