Heteronuclear complexes derived from the molecular ion [Hg(SCN)4]2−: Variance in bridging matrices, nuclearities and architectures with the change in complementary units

Abstract: Five neutral heteronuclear compounds of the type [M(tren)(μ-NCS) z Hg(SCN)4− z ] n [M=Cu/Zn/Cd, z =1, n =1, 1/2/3; M=Ni, z =2, n =2, 4; M=Pb, z =3, n =∞, 5; tren=tris(2-aminoethyl)amine] have been synthesized and characterized. X-ray structural analyses reveal that the tetrahedral [Hg(SCN)4]2− unit forms a single Hg–SCN–M end-to-end bridge with Cu(II), Zn(II) and Cd(II) of the complementary unit [M(tren)(S) z ]2+, affording dinuclear 1–3, respectively, with a trigonal bipyramidal geometry around the heterometal ions. In tetranuclear 4, four single Hg–SCN–Ni bridges bind two different octahedrally coordinated Ni(II) centers forming a cyclic loop. A heteropolynuclear chain with heptacoordinated Pb(II) in 5 results through alternate single and double NCS bridges. Multiple N–H⋯N, N–H⋯S, C–H⋯N, C–H⋯S hydrogen bonds in 1–5 and S⋯S interactions in 1–4 promote increased dimensionalities. EPR and variable-temperature (2–300K) magnetic data of 1 and 4 have been interpreted in terms of their structures. [Copyright &y& Elsevier]