Structural and spectroscopic characterization of DMF complexes with nitrogen, carbon dioxide, ammonia and water. Infrared matrix isolation and theoretical studies

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2018-02, Vol.190, p.423-432
• Main Authors: Sałdyka, Magdalena, Mielke, Zofia, Haupa, Karolina
• Format: Article
• Language: English
• Subjects: Ab initio calculations; Hydrogen bond; Matrix isolation; Molecular complexes; N,N-dimethylformamide; Van der Waals interaction
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2017.09.046

An infrared spectroscopic and MP2/6-311++G(2d,2p) study of the complexes between N,N-dimethylformamide (DMF) and nitrogen, carbon dioxide, water, ammonia trapped in solid argon matrices is reported. The 1:1 molecular complexes have been identified in the DMF/B/Ar matrices (B=N2, CO, H2O, NH3); their structures were determined by comparison of the spectra with the results of calculations. The analysis of the experimental and theoretical data indicate that the DMF-N2, CO complexes present in the matrices are stabilized by (C=)O⋯N and (C=)O⋯C van der Waals interactions. In turn, in the DMF-H2O, NH3 complexes the (C=)O⋯H(OH) and (C=)O⋯H(NH2) hydrogen bonding is present in which the carbonyl group of DMF acts as a proton acceptor. In all systems studied the C-H⋯X (X=N, C, O) bonding is a second intermolecular force stabilizing the planar complexes. Some spectral features indicate that for DMF-H2O, DMF-NH3 systems the nonplanar structures with the C=O⋯H interaction are also present. The study demonstrated the strong sensitivity of the CH stretching wavenumber to an involvement of the C-H and/or C=O groups of DMF in an intermolecular interaction. [Display omitted] •1:1 DMF-B molecular complexes (BN2, CO, H2O, NH3) are trapped in argon matrices.•DMF-N2, CO systems are formed by (C)O⋯N and (C)O⋯C van der Waals interactions.•DMF-H2O, NH3 complexes are stabilized by the (C)O⋯H hydrogen bonds.•CH stretch is very sensitive to interaction of CH and/or CO groups with B.