Search

Abstract Molecular and crystal structure of the complexes F 2 B(AcAcX) (X = I, OCOCH 3 , SCN) have been studied by XRD method. All the compounds manifest noticeable distortions of the chelate ring due to intermolecular interactions of fluorine atoms with atoms of the α-substituent as well as with carbon atoms of the chelate ring. First detailed assignment of FT-IR spectra registered in crystalline state and in solution and FT-Raman spectra in crystalline state of acetoxy- and thiocyanato-substituted complexes has been carried out basing on DFT/B3LYP calculations in 6-311G (d, p) basis set. Raman spectra of the complexes with X = OCOCH 3 , SCN have been obtained for the first time including their low frequency region, previously unobserved for these compounds. All spectral results have been discussed in comparison with those for previously reported IR spectrum of the iodo-substituted complex. Observed in vibrational spectra evidence of intermolecular interactions is consistent with XRD data. Both XRD and spectral results prove that intermolecular interactions (IMI) involving O 2 BF 2 moiety play the key role in the crystal packing of these compounds and govern their related properties in crystalline state. Revealed in this study correlations may be suitable in subsequent studies of physical and chemical properties of boron difluoride β-diketonates. Graphical abstract Image 1 Highlights • Structure of α-substituted boron difluoride acetylacetonates is determined by XRD. • DFT calculations of the complexes are performed. • Detailed assignment of bands in IR and Raman spectra of two complexes is done. • Marker bands that demonstrate evidence of intermolecular interactions are revealed. • Correlations are found: νCC α vs electrophilicity index and ΔνBF vs melting points. [ABSTRACT FROM AUTHOR]

• Raman spectra of the F2B(AcAcX) with X= = H, Cl, Br, I were measured. • DFT calculations of the dimer and tetramer models remarkably fit experiment. • Combined investigation of non-covalent interactions in crystalline was performed. • Vibrational coupling νBF 2 +δC α H is essential for the band assignment and correlations. DFT calculations were carried out for two dimer forms and tetramers to model equatorial and axial noncovalent intermolecular interactions in the crystalline samples of F 2 B(AcAcX), where X = H, Cl, Br, I. Vibrational frequency shifts for dimer and tetramer models in reference to their monomer frequency values were analyzed in terms of their correlation with calculated energetic characteristics and experimental spectral and geometrical features. The role of intermolecular vibrational coupling in the νBF 2 range of the parent compound was shown. RDG plots and NCI isosurfaces in combination with vibrational spectra were applied to discriminate and describe different kinds of molecular interactions in the crystalline state of the compounds. In particular, halogen bonding and van der Waals bonds were revealed. Image, graphical abstract [ABSTRACT FROM AUTHOR]