Can hybridization theory be applied to cobalt(III) complexes— A response to Pauling
✍ Scribed by C.K. Jørgensen
- Publisher
- Elsevier Science
- Year
- 1974
- Tongue
- English
- Weight
- 250 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0009-2614
No coin nor oath required. For personal study only.
✦ Synopsis
The suggestion of highly different radial functions of the five 3d orbitals is analyzed and shown not to rescue the hybridization description.
A recent commemorative volume [ 1 ] for De Broglie consisting of twenty articles about actual problems in quantum chemistry contains a contribution by Pauling and Keaveny which, to a large extent, is an answer to a paper [2] by the present author "The breakdown of the hybridization theory and the ligand field problem". Interestingly enough, Pauling and Keaveny do not argue that linear combinations of central atom orbitals of the d2sp3 type might be discussed even in the case of highly disparate radial functions, and they agree that in isolated atoms, the average radii of 3d, 4s, and 4p orbitals have the proportion [2] close to 1 : 3 : 4. Rather, Pauling and Keaveny suggest that some of the d orbitals contract and correspond to the non-bonding orbitals frequently treated by ligand field theory [3] and a few orbitals expand strongly obtaining radii comparable with 4s and 4p and participating in bonding after hybridization. Whereas 3d1° in a nickel atom with five identical orbitals has the average radius 0.55 A, the distribution (expanded)4 (contracted) lo-q for 4 = 4 corresponds [l] to average radii 1.64 and 0.43 A and the most stable situation (4 = 2) 3.31 and 0.48 A. Actually, this argument already applies to an atom in spherical symmetry and is comparable to the helium atom ground state having the Slater exponent 1.687 increased and decreased half a unit for the contracted and expanded 1 s orbital in the "unrestricted Hartree-Fock solution" with two different radial functions and slightly lower energy.