Financiado para publicación en acceso aberto: Universidade da Coruña/CISUGThe following are the Supplementary data to this article: https://ars.els-cdn.com/content/image/1-s2.0-S0167732221018882-mmc1.docx[Abstract] In a previous paper some of us presented the structure and some properties of a new family of ionic liquids, ILs, with a common cation, 1-butyl-3-methyl imidazolium (the popular [C4C1Im]⁺ or [BMIM]⁺) and a variety of anions based in thiocyanate (SCN)¯: one reference sample and ten with anionic metal complexes of different valences: Al¹¹¹, Mn¹¹, Fe¹¹, Cr¹¹¹, Ni¹¹, Hg¹¹, Zn¹¹, Co¹¹ and Cu¹, resulting, respectively, [BMIM](SCN), [BMIM]₃ Al(SCN)₆, [BMIM]₄ Mn(SCN)₆, [BMIM]₃ Fe(SCN)₆, [BMIM]₃ Cr(SCN)₆, [BMIM]₄ Ni(SCN)₆, [BMIM]₂ Hg(SCN)₄, [BMIM]₂ Zn(SCN)₄, [BMIM]₂ Co(SCN)₄ and [BMIM]₃ Cu(SCN)₄. In this paper we show experimental measurements of electrical conductivity of these ILs in a broad temperature range (about 90 K). Viscosity has been measured for six compounds in a wide temperature range. In addition, the diffusion coefficient for both ions forming the IL has been measured for some of the samples using NMR-Dosy technique. In spite of being very similar compounds from a chemical point of view, they present very different transport property values. Thus, viscosity varies more than two orders of magnitude among those metal thiocyanate ILs, being the highest for the compound with Al and the lowest for that with Hg. Moreover, differences between ionic conductivity and diffusion coefficient values extend more than one order of magnitude among the thiocyanate ILs. These three properties will be related in pairs, thus through Walden’s rule we compare molar conductivity and fluidity, while using Kohlrausch’s law and Nerst-Einstein equation molar conductivity and diffusion coefficient are related. Also, diffusion coefficient and fluidity (the inverse of viscosity) are compared by means of Stokes-Einstein relationship. In addition, we calculate the Laity interionic friction coefficients for both anions of the IL with Hg. Finally, a theoretical model is suggested to explain all the experimental evidences reported.We acknowledge the financial support of Ministerio de Economía y Competitividad MINECO) (MAT2017-86109-P and MAT2017-89239-C2-(1.2)-P); and Xunta de Galicia (AGRU 015/11. GRC ED431C 2016/001 and ED431D 2017/06). All these research projects were partially supported by FEDER. Also, D.A. acknowledges Gil Dávila Foundation for his postgraduate grant. Funding for open access charge: Universidade da Coruña/CISUG.Xunta de Galicia; ED431C 2016/001Xunta de Galicia; ED431D 2017/06https://ars.els-cdn.com/content/image/1-s2.0-S0167732221018882-mmc1.doc
