Molecular orbital treatments

For this class of thiazoles most of the chemical and physicochemical studies are centered around the protomeric equilibrium and its consequences. The position of this equilibrium may be determined by spectroscopic and titrimetric methods, as seen in each section. A simple HMO (Hiickel Molecular Orbitals) treatment of 2-substituted compounds however, may, exemplify general trends. This treatment considers only protomeric forms 1 and 2 evidence for the presence of form 3 has never been found. The formation energy reported in Table 1 is the energy difference in f3 units. 

Thermodynamic properties (71,72), force constants (73), and infrared absorption characteristics (74) are documented. The coordinatively unsaturated species, Ni(CO)2 and Ni(CO)2, also exist and the bonding and geometry data have been subjected to molecular orbital treatments (75,76). 

Coulson, C. A., and Fischer, I., Phil. Mag. 40, 386, Notes on the molecular orbital treatment of the hydrogen molecule."... 

Taylor, R., Proc. Phys. Soc. A64, 249, Complete molecular orbital treatment of the system H4. ... 

The foregoing discussion indicates that while there are difficulties in the way of a bonding role for 3d orbitals, for certain situations at least it is possible to conceive of ways in which these difficulties may be overcome. However, it is necessary to say that even for hypervalent molecules such as SF6 which seem to require the use of d orbitals, there are molecular orbital treatments not involving the use of d orbitals. In fact, as shown by Bent in an elegant exposition12, the MO model of SF6 involving the use of d orbitals is only one of several possibilities. The octahedral stereochemistry of SF6, traditionally explained in... 

APPENDIX A-MOLECULAR ORBITAL TREATMENT OF MANY-ELECTRON SYSTEMS... 

TOWARDS AN ACCURATE SEMI-EMPIRICAL MOLECULAR ORBITAL TREATMENT OF COVALENT AND NON-COVALENT BIOLOGICAL INTERACTIONS... 

However, more quantitative molecular orbital treatments still leave scope for improvement, and in particular a systematic treatment of the whole metallocene series, rather than of isolated members such as ferrocene, is much to be desired. Moreover, theoretical studies have generally neglected the bis-arene and mixed sandwich series, and in both cases such treatments would be of value in indicating the extent to which the mainly metal n level is or is not less anti-bonding than in the metallocenes. In this connection it is interesting to note that in the (Ch) Cr(Cp)- anion the mainly metal n dxz, dyz ) level may still lie relatively high since esr measurements 1 78) indicate the odd electron to... 

Our work was initiated on the reduced ternary molybdenum oxides with the thought that the metal cluster electron count (MCE) should be variable for the Mo308 cluster units. Based on Cotton s previous molecular orbital treatment of such clusters (16) it appeared that MCE s from 6 to 8 could be accommodated, but it was not clear whether the seventh and eighth electrons would occupy bonding or antibonding orbitals with respect to the M-M interactions. We thus set about to determine this from structural data on suitable compounds. The attempted replacement of Zn2+ with Sc3+ to secure the compound ZntSc°Mo308 was conducted via the reaction shown in equation 1. 

Scattering, Reactive, in Molecular Beams (Herschbach). Self-Consistent Field Molecular-Orbital Treatment of 10 319... 

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