A pseudoatom molecular orbital approach to substituent effects in organic Compounds. III. HH coupling constants in substituted ethylenes, ethanes, and benzenes

Abstract Ring and ester proton chemical shifts in six series of substituted methyl pyridinecarboxylates have been measured. Results for ring protons ortho and para to the substituent can generally be accounted for by additive substituent, ester and nitrogen effects. Shifts for protons meta to the substituent, when compared with analogous shifts in monosubstituted benzenes, provide evidence of substituent–nitrogen interactions. In particular, a special effect is noted for series where both the proton and substituent are adjacent to the nitrogen. The origin of this effect is discussed. The ester proton results lead to essentially the same conclusions. Although this probe is much less sensitive to substituent effects, the same special effect is evident for the methyl 6‐X‐picolinate series.

Chemical shift

10.1002/mrc.1270070110

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Citations (18)

The use of population localised orbitals to interpret molecular orbital calculations

Chemical Physics (1979)

W.S. Verwoerd

Slater-type orbital

Localized molecular orbitals

Orbital overlap

Non-bonding orbital

10.1016/0301-0104(79)80115-9

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Citations (35)

Some new theorems and methods for establishing the relationship between the symmetry of a molecular orbital and its energy

Journal of the Chemical Society Faraday Transactions 2 Molecular and Chemical Physics (1978)

W. T. Dixon

Some theorems are derived connecting the symmetry properties of molecular orbitals with their relative energies, for particular types of system. For example, when two identical fragments are joined by a single atomic orbital, or by two identical orbitals, the energies of the symmetrical m.o.s. alternate with those of the antisymmetrical m.o.s.The theorems are used in the construction of correlation diagrams in which chosen interactions within a system are varied. By this purely diagrammatical procedure it is possible to estimate the relative m.o. energies in systems for which the m.o. parameters are not specified exactly.

10.1039/f29787400511

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Citations (3)

The stereochemistry of metal complexes as an indication of f-orbital participation in the metal–ligand bonding

Journal of the Chemical Society A Inorganic Physical Theoretical (1967)

S. F. A. Kettle A. J. Smith

The irreducible representations spanned by the seven f-orbitals in all common point group symmetries are given. Those point groups in which an irreducible representation is spanned by the f-orbitals but not by s-, p-, or d-orbitals are discussed, and molecular geometries which would be indicative of f-orbital participation described. A survey of the available crystal structure data is given and compared with the theory.

Orbital overlap

Representation

Crystal (programming language)

10.1039/j19670000688

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Citations (16)