Metal molecules, heteronuclear diatomic

In Chapter 1 we saw that in moving from homonuclear to heteronuclear diatomics a new factor enters - the atom characters are distributed differently over the filled and unfilled MOs. As only the filled orbitals contribute to the atomic charges, the Mulliken charge distribution reflects the polarity of the molecule. Similar information for the HOMO and FUMO permitted us to discuss properties such as Lewis acidity and basicity in terms of frontier-orbital characteristics. As we were able to unravel the DOS of the metal chain in terms of AO type, we can also interrogate the DOS of a heteroatomic system for information on the distribution of atomic character over the total DOS. That is, we can reveal the contributions or character of a chosen atom to the DOS. We can begin to appreciate the power of this tool by... 

Dissociation Energies, D /kJ mol- of Heteronuclear Diatomic d-Transition Metal Molecules. 

Two models have been used to predict dissociation energies for heteronuclear diatomic transition metal molecules, the valence bond model (9), which proposes a polar single bond, and the atomic cell model (7). Their success when compared with experiment is indicated by the following examples ... 

The maximum bond energy of a heteronuclear diatomic transition metal molecule has been suggested (2) as (670 84) kJ mol l. 

Table 6.1. Gaseous heteronuclear diatomic molecules AB(g) hydrogen halides HX interhalogen compounds XK alkali metal hydrides MH, and inter-alkali-metal compounds MM. Electric dipole moments, ionic characters, qjc equilibrium bond distances. Re, vibrational wavenumbers, < dissociation energies at zero K, Dq rednced masses of the predominant isotopomers, /tm and force constants,. ...

Table 8.1. Atomic charges in the 21 heteronuclear diatomic molecules formed hy comhination of H, the alkali metal Li, Na or K, and the halogen F, Cl or Br atoms experimental and calculated ionic characters, q Q atomic charges calculated by natural atomic orbital (NAO) analysis, and by topological analysis of the electron densities (AIM) [2]. All charges in atomic units. Note that the chemical formulae have been written in such a way that the atom carrying net positive charge is listed first.

Some homo- and heteronuclear small diatomic (H2, N2, 02, CO, and NO) and triatomic (C02, N20, and N02) molecules engage in strong interactions with transition metals, with consequent changes in structure and reactivity. We deal with the chemistry of NO and related redox derivatives, NO+ (nitrosonium) and NO-/ HNO (nitroxyl),1 as a case study for using state-of-the-art spectroscopic and kinetic methodologies together with modem theoretical calculations in order to visualize the impact of nitrosyl coordination. 

Comparison of Formation of Homonuclear and Heteronuclear Alkali Metal Diatomic Molecules in Bound Excited States by PA... 

Wang, H. and Stwalley, W.C., Ultracold photoassociative spectroscopy of heteronuclear aUcali-metal diatomic molecules, J. Chem. Phys., 108, 5767,1998. 

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