Theoretical bond length

Quantum mechanical calculation of molecular dynamics trajectories can sim ulate bon d breakin g and frtrm ation.. Although you dt) n ot see th e appearance or disappearan ce ofhonds, you can plot the distan ce between two bonded atom s.. A distan ce excccdi n g a theoretical bond length suggests bond breaking. 

The recently determined X-ray crystal structure of cyclopentacorannulene 25 provides an additional opportunity to test the performance of theory in predicting the minimum energy structures of nonplanar conjugated systems. Table 4 presents the C-C bond lengths in the crystal and a comparison with ab initio values calculated at HF/3-21G and HF/6-3IG levels. The agreement between experimental and theoretical bond lengths is very satisfactory with root mean square devia-... 

Experimental and Theoretical Bond Lengths (A) in Chrysene (Burns and Iball, 1960)... 

Table 1 Selected theoretical bond lengths and bond angles...

Gibbs, G. V., E. P. Meagher, M. D. Newton, and D. K. Swanson (1981). A comparison of experimental and theoretical bond length and angle variations for minerals, inorganic solids and molecules. In Structure and Bonding in Crystals, Vol. I (M. O Keeffe and A. Navrotsky, eds.) New York Academic Press, pp. 195-226. 

Figure 4.15 shows the calculated equilibrium geometries of the group 14 complexes Si2(NHC )2-Pb2(NHC )2 [47]. The theoretical bond lengths and angles of the molecules agree quite well with the experimental values of the complexes Si2(NHC° PP)2-Sn2(NHC PP)2. The lead complex Pb2(NHC )2 has not yet been synthesized. 

Table 2. Theoretical bond lengths and hydration energies compared with experimental data (in parentheses). Values in bold are relativistic density functional results from Collins (1997) calculated using the Perdew (1986) exchange-correlation functional. Values in brackets are HF results.

The bond lengths given in Table P8-10 have been reported for ovalene (XXVI). Using a library source or a computer program, obtain HMO bond orders for ovalene and calculate theoretical bond lengths using a relation from Section 8-12. Make a comparison plot for ovalene of the type shown in Fig. 8-16. (See caption of Fig. 8-16 for values of k and s.)... 

Table 2 shows experimental and theoretical bond lengths for a set of charged hexacarbonyls M(CO)g which are isoelec-tronic with W(CO)e, calculated by MP2/II and DFT/II using two different functionals (BP86 and B3LYP). The theoretically predicted M-CO distances are always slightly longer than the experimental values taken from X-ray structure analysis. The... 

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