Carbodiylides C(ECp*)₂ (E=B–Tl): Another Class of Theoretically Predicted Divalent Carbon(0) Compounds

Nearly Degenerate Isomers of C(BH)2: Cumulene, Carbene, or Carbone?

“…A similar shape was found for the HOMOÀ1 of the substituted homologues CA C H T U N G T R E N N U N G (ECp*) 2 (Al to Tl), attesting to some E-E attraction. [7] The electron-density profile of the HOMOÀ1 accounts for the rather acute central bond angles in CA C H T U N G T R E N N U N G (ECp*) 2 (Al to Tl) and 1 b. This density is visible in the area of charge concentration between the boron atoms in the Laplacian distribution of bent C(BH) 2 (Figure 4b).…”

“…The change of a local-mode frequency w a from the corresponding normal-mode frequency w m in an ACS is measured by the coupling frequency [Eq. (7)], which absorbs all masscoupling effects with all other N vib À1 local modes. The sum of all j w coup j adopts a minimum if the set of local vibrational modes is unique.…”

“…These force con-stants can be converted into more interpretable bond-order parameters (n) with the help of suitable reference molecules (Scheme 1). [61][62][63][64] For this purpose we assume the reference bond orders n BC = 1 for CH 3 BH 2 (2), n BC = 2 for H 2 C=BH (3), n BB = 1 for C 4 B 2 H 10 (4) (diborocyclohexane), n BB = 2 for HB=BH (5), n BH = 1 for BH 3 (6), and n BH = 1 = 2 for B 2 H 6 (7) (electron deficient bonding in H-B-H bridges). Accordingly, the following power relationships are obtained from the B3LYP/6-31GA C H T U N G T R E N N U N G (d,p) data in Table As discussed in the section above, the p bonding in 1 a results for two two-electron three-center B À C bonds, which together with the s bonding should lead to a bond order significantly larger than 2.…”

“…[1c-g] The carbone bonding model nicely explains why C 3 O 2 has a bent gas-phase equilibrium geometry with aA C H T U N G T R E N N U N G (C-C-C) = 1568, [5] the larger bending angle relative to carbodiphosphoranes and carbodicarbenes coming from the higher p-acceptor strength of CO. [6] Theoretical searches for synthetically viable carbones have found that carbodiylides CA C H T U N G T R E N N U N G (ECp*) 2 (E = Al to Tl; Cp* = pentamethylcyclopentadienyl) are strongly bonded molecules with E-C-E bending angles of 100-1058. [7] In contrast to the heavier group 13 homologues, CA C H T U N G T R E N N U N G (BCp*) 2 was computed to have a linear B-C-B arrangement. This finding was explained in terms of a Cp*B=C=BCp* structure with electron-sharing bonds and boron in the formal oxidation state III, at variance with the carbodiylides CA C H T U N G T R E N N U N G (ECp*) 2 (E = Al to Tl) that possess donor-acceptor bonds Cp*E!…”

Structure and property of complexes of group 13 diyl containing subvalent silylone using energy decomposition analysis with natural orbitals for chemical valence

“…[19,20] Recently, Frenking et al reported the quantum-chemical calculations with the results suggested that the carbone ligands C(XCp*) 2 with X = B -Tl are synthetically accessible compounds that belong to the growing numbers of divalent carbon(0) compounds called carbones. [21] The main purpose of this investigation is to apply charge and energy decomposition analysis in a description of metal-ligand bonding in donoracceptor interaction of silylone ligands Si(XCp*) 2 (X = B, Al, Ga, In, Tl) in transition metal complexes [W(CO) 5 -Si(XCp*) 2 ] (W5-SiX) (scheme 1).…”