Affiliation: | aInstitute of Inorganic Chemistry and Metallurgy of Rare Elements, Wrocław University of Technology, ul. Wybrzeze Wyspiańskiego 27, 50-370 Wrocław, Poland bInstitute of Physics, Wrocław University of Technology, Wrocław, Poland cInstitute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, 50-950 Wrocław, Poland dFaculty of Computer Sciences and Management, Wrocław University of Technology, Wrocław, Poland |
Abstract: | Nickel(II) chromate complex with imidazole (HIm) was isolated from the [Ni2+–HIm–CrO42−] system in various experimental conditions, i.e. reagent molar ratios and nickel(II) salts. The catena(μ-CrO4-O,O′)[Ni(HIm)3H2O] (1) crystallizes in monoclinic crystal system—space group P21/n with cell parameters: a=11.784(2), b=8.899(2), c=13.934(3) (Å), β=95.19(3) (°). The unit cell contains two independent helixes, left- and right-handed, stabilized by intrahelical and interhelical hydrogen bonds (HB) and π–π interactions. The cis coordination of the CrO42− anions and the HB systems appeared to be the main determinants of the helical architecture. To the best of our knowledge the cis-chromate coordination was observed for the first time. The cis coordination causes the distortion of the nickel octahedron, which was analysed by 4 K single crystal electronic spectra with D4h symmetry approximation (gaussian resolution and crystal field parameters). This symmetry was also confirmed with the polarised electronic spectra. The magnetic properties of the complex suggest the occurrence of weak intrachain antiferromagnetic interactions between the magnetic NiII center. The computational DFT studies of complex 1 assuming three possible isomers mer[(HIm)3]–cis[(CrO42−)2], mer–trans and fac–cis suggested that the main contribution to the stability of 1 might have interhelical and intrahelical hydrogen bonds. |