Mario A. Natiello

On the quantum theory of valence and bonding from the ab intio standpoint

Abstract Ab initio calculations of valence, degree of bonding and anisotropy were performed according to the definitions by Armstrong et al. Some numerical results are given for selected molecules.

The through-space transmission of 13C19F coupling constants via an intermediate bond: A polarization propagator analysis

Abstract Inner projections of the polarization propagator were used to study the indirect through-space transmission of the Fermi contact term of CF couplings via a CX (X = F, H) intermediate bond. When X = H a large capability for transmitting this component is observed. But for X = F a notable inhibition of this transmission mechanism is observed. The role of the fluorine lone pairs in this behaviour is discussed.

A polarization propagator analysis of the through-space transmission of non-contact terms of FF coupling constants

Abstract The IPPP method (inner projections of the polarization propagator) is extended to include the orbital and dipolar interactions of spin-spin coupling constants. As an example, calculations of the through-space components of FF couplings are carried out at the INDO level of approximation in fluorinated derivatives of cis-fluoropropene. The orbital and dipolar through-space couplings are much smaller than the Fermi contact term. However, the first one, though small, is not negligible.

Reply to “comments on the quantum theory of valence and bonding: Choosing between alternative definitions”

Abstract In this Reply, to the preceding, Comment of Mayer, we indicate that there is no reason to prefer Mayers definitions to ours (or conversely) when in the usual range of validity.

A polarization propagator analysis of the geminal 31P-31P coupling in bis(difluorophosphino)amine⋆

Inner projections of the polarization propagator (IPPP) are used to decompose in through-space and through-bond contributions the two-bond P-P coupling in PF2-NH-PF2. This study is carried out using a ground state INDO wavefunction. Results for a phosphorus sp and spd atomic basis sets are compared. Several experimental trends are correctly reproduced using either of them. It is concluded that the overlap of the lone pair of both P atoms constitutes a very efficient pathway for transmitting through-space the spin information associated to the Fermi contact term.

Transmission mechanisms of four-bond 19F19F coupling constants in fluoropropenes: A theoritical and experimental study

Abstract Four-bond FF couplings were measured in cis- and trans-isomers of 1,3-diflouro- and 1,3,3,3-tetraflouro-propene. These couplings show a pronounced depedence on the member of flourines attached to the sp 3 carbon atom. This dependence is much larger for the cis-isomers than for the trans ones. A theoretical analysis of transmission mechanisms of the Fermi contact, orbital and dipolar interacting terms is carried out using inner projections of the polarization propagator at the INDO level of approximation. For each interacting term three different coupling pathways are considered, namely, through-space, σ- and π-electron contributions. Trends for each mechanism are discussed and results are compared with the experimental values.

The Indirect Through-Space Transmission of C—H Couplings Via an Intermediate Bond

The transmission of a C—H coupling via one intermediate C—H bond in N-methyl-2-pyridone is studied. The IPPP method is used to predict the qualitative features of this and other couplings of the molecule. Experimental results are also presented, and compared with the theoretical predictions. The combined use of theory and experiment allows to provide a compatible picture of the structural properties of the molecule as well as of the transmission mechanisms involved in the different couplings.