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Innovative Medicines & Omics Synthesis and docking of diorganotin (IV) chelates

Figure 2. The optimized structure of Sn-complexes calculated using the B3LYP/LanL2DZ method

the ∠N–Sn–S angles are approximately 78°. In addition, a 3.2.2. Global reactivity descriptors
wider and more irregular range (96° – 120°) is observed Frontier orbital theory explains molecular behavior
for bond angles between Sn and the methyl carbon atoms through two key electronic states: the HOMO and the
(∠C–Sn–S and ∠C–Sn–C). first empty level above it (LUMO). The energy difference
As the bulkiness of the substituent increases, a slight between these frontier orbitals serves as a valuable indicator
decrease in the ∠O–Sn–N angle is observed: from methyl of the molecule’s stability and potential reaction pathways.
to ethyl, the reduction is 0.36°, from ethyl to phenyl, This energetic separation helps predict how readily the
0.07°, and from phenyl to chlorophenyl, 0.14°. A similar molecule can participate in chemical transformations.
trend is seen in the ∠N–Sn–S angle (0.27° → 0.20° → A small HOMO-LUMO gap indicates that the molecule
0.12°). Overall, the DFT-optimized structures reveal requires less energy to excite electrons, suggesting higher
no significant variations in Mulliken charges or bond reactivity, while a large gap implies greater chemical
lengths across chelates with different substituents, except stability.
for differences in bond angles. A separate table (Table 6) The HOMO reflects a molecule’s ability to donate
presents the computed electronic parameters, including the electrons, corresponding to ionization potential, while the
electron donation and acceptance tendencies (ionization LUMO reflects its ability to accept electrons, corresponding
potential and electron affinity), electronic distribution to electron affinity. Ionization potential represents the
characteristics (electronegativity and chemical hardness), energy needed to remove an electron from the molecule,
and reactivity indicators (electrophilicity index and with a high value indicating greater stability and inertness,
chemical potential). while lower values suggest increased reactivity. Electron

Volume 2 Issue 3 (2025) 73 doi: 10.36922/IMO025140019