The first example of a direct Cu+– bond. Synthesis and crystal structure of two closely related copper(I) hexafluorosilicate π-complexes with 1-allylbenzotriazole of [Cu2(C6H4N3(C3H5))2(H2O)2SiF6]·2H2O and [Cu2(C6H4N3(C3H5))2(CH3OH)2(H2O)2]SiF6 compositio

[Cu2(C6H4N3(C3H5))2(H2O)2SiF6]·2H2O (I) and [Cu2(C6H4N3(C3H5))2(CH3OH)2(H2O)2]SiF6 (II) π-compounds were obtained by alternating current electrochemical synthesis, starting from ethanol–methanol solution containing 1-allylbenzotriazole, H2SiF6, CuSiF6·4H2O and copper wire electrodes. Both compounds were X-ray structurally investigated. In complex I a mid-point of the CC bond of one 1-allylbenzotriazole (L) molecule, the nitrogen atom from another L moiety, the oxygen atom from a water molecule and the fluorine atom from a SiF 6 2 - anion form the trigonal-pyramidal environment of the CuI center. One more water molecule is fixed in the crystal space by strong O–H⋯F and O–H⋯O hydrogen bonds. The bridging function of the L, Cu+ and SiF 6 2 - units results in a formation of infinite metal-organic layers. The metal surrounding in II differs from that in I by a presence of oxygen atom from the methanol molecule instead of fluorine atom from the SiF 6 2 - anion. An appearance of ⋯ SiF 6 2 - –CH3OH–Cu+–L–Cu+–H2O⋯ infinite layers in II instead of ⋯ SiF 6 2 - –Cu+–L–Cu+⋯ in I leads to a noticeable elongation of the unit cell of II along [0 1 0] direction in comparison with I. The structure I represents the first known example of the Cu+– SiF 6 2 - bond.