Molecular structure geometrical parameters

Our DFT calculations revealed that coordination of nitric oxide to the series of intrazeolite TMI leads to the formation of the bent MNO adducts of various spin states exhibiting generally the Cs microsymmetry with mirror plane defined by the M-N-0 moiety. Optimized structures of some representative mononitrosyl complexes are depicted in Figure 2.8, and their selected geometric parameters and molecular properties are listed in Table 2.4. 

Doms, L., H. J. Geise, C. Van Alsenoy, L. Van den Enden, and L. Schafer. 1985. The Molecular Orbital Constrained Electron Diffraction (MOCED) Structural Model of Quadricyclane Determined by Electron Diffraction Combined with Ab Initio Calculations of Potential and Geometrical Parameters. J. Mol. Struct. 129, 299-314. 

The key observation is that there is a systematic relationship between the geometrical parameters defining the reaction . When the Y-M bond is lengthened (Ar) under the various influences of a particular crystal and molecular environment, the rest of the tetrahedral structure (YMX angle, M-X bond length, r,) responds in a standard, predictable, way. [See, for example, the correlation shown in Fig. 5, which is discussed also by Dunitz (1979).] This must represent, in the particular circumstances, the most favourable, i.e. the minimum energy, pathway for the structural change... 

This is not all. In fact, the structural and dynamic information at a molecular level that are contained in the NRMD profiles of a paramagnetic system comprise geometrical parameters (distances and angles), which determine the position of protons relative to the paramagnetic site the... 

Computational quantum chemistry has emerged in recent years as a viable tool for the elucidation of molecular structure and molecular properties, especially for the prediction of geometrical parameters, kinetics and thermodynamics of highly labile compounds such as nitrosomethanides. However, they are difficult objects for both experimental (high toxicity, redox lability, high reactivity, explosive character etc.) and computational studies, even with today s sophisticated techniques (e.g. NO compounds are often species with open-shell biradical character which requires the application of multi-configuration methods). 

The molecular structure of the surfactant influences the form of the aggregate, and there are some geometrical empirical rules (Israelachvili et al, 1977, Israelachvili, 1992) illustrated in Figure 9.2, based on the geometrical parameters of the surfactant molecule. In particular the volume V occupied by the surfactant, the head area... 

Figure 4.9 Molecular representation of ((AdAr0)3tacn)U(C02) with core structure and geometric parameters in A and degrees, and possible mechanism of C02 reduction by a less-bulky U1" complex [75].

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