N-[difluoro(methyl)silyl]carboxamides: Synthesis, structural features and theoretical estimating of Si←O dative bond energy

• The new original method of the synthesis of N-[difluoro(methyl)silyl]methylcarboxamides was proposed. • X-ray analysis of tree new N-[difluoro(methyl)silyl]carboxamides 1-3 was carried out. • The lengths of coordination bonds Si←O in studied structures depends on the presence and volume of substituents. • The energies of dative bond in amides 1-3 are near to coordination bonds in metal complexes according AIM analysis. The new original method of the synthesis of N-[difluoro(methyl)silyl]methylcarboxamides and related compounds based on the reaction of alkylation of N-trimethylsilyl derivatives by bifunctional silane ClCH 2 SiF 2 Me was use to prepare of N -{[difluoro(methyl)silyl]methyl}- N -methylacetamide, N -{[difluoro-(methyl)silyl]methyl}benzanilide and phenyl-N-phenyl-N-{[difluoro(methyl)silyl]methyl}carbamate. The structures of these compounds confirmed by NMR, FTIR and X-ray analysis. According to X-ray analysis data the lengths of coordination bonds C=O→Si in studied compounds are 1.969, 2.000 and 2.176 Å respectively. The lengths of Si-F ax. comprise 1.686, 1.661 and 1.632 Å respectively. QTAIM analysis was used to estimate the energy of co-ordination bond C=O→Si in these amides. Calculated data shows that its value varies within 14-30 kcal/mol that close to the energy of co-ordination bond in some metal-complexes.