Synthesis, experimental and computational studies of new (trifluorosilyl)propyl derivatives of cyclic imides of dicarboxylic acids

New (trifluorosilyl)propyl derivatives of cyclic dicarboxylic acid imides 1-[3-(trifluorosilyl)propyl]pyrrolidine-2,5‑dione, 1-[3-(trifluorosilyl)propyl]piperidine-2,6‑dione and 2-[3-(trifluorosilyl)propyl]-1H-isoindole-1,3(2H)‑dione were synthesized and structurally characterized by FTIR, NMR spectroscopy, mass spectrometry and elemental analysis. Intramolecular coordination interaction O→Si and the influence of the hydrocarbon chain length on the strength of the coordination interaction in Si-fluoroethyl and Si-fluoropropyl derivatives of cyclic imides of dicarboxylic acids were characterized by DFT calculations. The geometric, energetic and electronic characteristics of the investigated molecules were also determined. The intramolecular O→Si coordination bond, closing the six-membered chelate cycle SiCCN(C=O), is observed in the (trifluorosilyl)ethyl derivative phthalimide in the gas, and in the (trifluorosilyl)ethyl derivative succinimide the O→Si coordination bond is observed both in the gas phase and in DMSO solution. The coordination bond O→Si, closing the seven-membered chelate cycle SiCCCN(C=O), is found in the (trifluorosilyl)propyl derivative succinimide in the gas phase. Quantum chemical calculations were carried out at the M06/6–311G** and MP2/6–311++G**//M06/6–311G** levels with the 6–311G** basis set.