The number of "incident pi bonds" is the sum of bond orders of explicitly connected atoms minus the "explicit degree".
Total potential energy of system U is expressed as a sum of bonding energies for all pairs of atoms forming this system.
Nevertheless, the rule to conform to the SMILES specification remains the same: square brackets are used if the total sum of bond orders is not equal to the standard valence.
Introduction of two amines on the pyridine ring enhances the electron-donating ability of the ligands (Scheme 10) which has also been indicated through crystal structure of complexes (17, 20, 23), and the sum of angles around nitrogen of N-heterocycle is 353° 360° (for example, the sum of bond angles in complex 20 = 360°, Fig. 5) which reveals sp2 hybridization of N-atom.
Total potential energy of system U is expressed as a sum of bonding energies for all pairs of atoms forming this system U={displaystyle sum_i{displaystyle sum_{j> i}left[{V}_Rleft({r}_{i j}right -{B}_{i j}right -{B}_{i}_{i j}^{V}_Rleftt]}} (3).
Non polar and internal energy contributions, which come from the sum of bond, angle and dihedral energies, constitute a small part of the enthalpy.
Valence sum rule: The sum of bond valences around any atom should be equal to the atomic valence, (eq 5).
Therefore if the bond valence, s ij, is set equal to the bond flux, the sum of bond valences around any ion, i, is equal to its valence, V i.
If it does, the atom's formal charge FC is added to the atom's positive or negative sum of bond orders iBOS to yield its oxidation state [Eq. (1)].[ 14b] This relationship is illustrated for CO and [Cr(CO 6] in Figure 7.
In contrast, the second principal component (PC2) includes only anionic descriptors: MWA, the molecular weight; nSKA, the number of non-H atoms; nBOA, the number of non-H bonds; SCBOA, the sum of conventional bonds (H-depleted); nDBA, number of double bonds; nOA, the number of oxygen atoms; nSA, the number of sulfur atoms; nFA, the number of fluorine atoms; and nHetA, the number of heteroatoms.
