Synthesis, crystal structures, Hirshfeld surfaces and DFT calculations of two isomers of oxaspirocyclic compound

Abstract

Two isomers of oxaspirocyclic compound: 3-cyclopentyl-1,5-dioxaspiro[5.5]undecane-2,4-dione (Z-1) and 8-cyclohexyl-6,10-dioxaspiro[4.5]decane-7,9-dione (Z-2) were synthesized by the reaction of cycloalkanones with distinct dioxaspiro moieties in a formic acid-triethanolamine and DMF solution. Compound Z-1 was monoclinic, P 1 21/c 1 space group with lattice parameters: a = 10.2056(11) Å, b = 5.9697(5) Å, c = 21.7646(18) Å, β = 90.985(4) °, V = 1325.8(2) Å3, Z = 4, F(000) =544. Compound Z-2 was triclinic, P-1 space group with lattice parameters: a =5.761(2), b = 10.310(4), c = 12.377(5) Å, α =68.294(4) °, β = 79.837(5) °, γ = 87.492(5) °, V =672.1(4) Å3, Z = 2, F(000) = 272. The IR spectra were compared with the calculated vibrational frequencies using the DFT/B3LYP/ G-31(d, p) method. It was observed that the energy gaps of Z-1 and Z-2 were 7.075 eV and 7.073 eV, respectively, indicating lower chemical reactivity between the two molecules. Intermolecular interactions were investigated by Hirshfeld surface, showing predominant H···H interactions in the two molecules. In addition, the stabilization energy and the nucleophilic and electrophilic attack regions were studied by NBO and MEP analysis, respectively.