Two New Groups of Homoleptic Rare Earth Pyridylbenzimidazolates: (NC12H8(NH)2)[Ln(N3C12H8)4] with Ln - Y, Tb, Yb, and [Ln(N3C12H8)2(N3C12H9)2][Ln(N3C12H8)4](N3C12H9)2 with Ln - La, Sm, Eu

The compounds (NC12H8(NH)2)[Ln(N3C12H8)4], Ln = Y, Tb, Yb, and [Ln(N3C12H8)2(N3H8)2(N3C12H9)2][Ln(N3C12H8)4](N3C12H9)2, with Ln = La, Sm, Eu, were obtained by reactions of the group 3 metals yttrium and lanthanum as well as the lanthanides europium, samarium, terbium, and ytterbium with 2-(2-pyridyl)-benzimidazole. The reactions were carried out in melts of the amine without any solvent and led to two new groups of homoleptic rare earth pyridylbenzimidazolates. The trivalent rare earth atoms have an eightfold nitrogen coordination of four chelating pyridylbenzimidazolates giving an ionic structure with either pyridylbenzimidazolium or [Ln(N3C12H8)2(N3C12H9)2]+ counterions. With Y, Eu, Sm, and Yb, single crystals were obtained whereas the La- and Tb-containing compounds were identified by powder methods. The products were investigated by X-ray single crystal or powder diffraction and MIR and far-IR spectroscopy, and with DTA/TG regarding their thermal behavior. They are another good proof of the value of solid-state reaction methods for the formation of homoleptic pnicogenides of the lanthanides. Despite their difference in the chemical formula, both types (NCi2H8(NH)2)[Ln(N3C12H8)4], Ln = Y (1), Tb (2), Yb (3), and [Ln(N3C12H8)2(N3C12H9)2][Ln(N3C12H8)4](N3C12H9)2, Ln = La (4), Sm (5), Eu (6), crystallize isotypic in the tetragonal space group /41. Crystal data for (1): T= 170(2) K, a = 1684.9(1) pm, c == 3735.0(3) pm, V= 10603.5(14) x 10^6 pm^3 R1 for Fo > 4a(Fo) = 0.053, wR2 = 0.113. Crystal data for (3): T = 170(2) K, a = 1683.03(7) pm, c = 3724.3(2) pm, V = 10549.4(14) x 10^6 pm^3 R1 for Fo > 4a(Fo) = 0.047, wR2 = 0.129. Crystal data for (5): T= 103(2) K, a = 1690.1(2) pm, c - 3759.5(4) pm, V= 10739(2) x 10^6 pm^3 R1 for Fo > 4a(Fo) = 0.050, wR2 = 0.117. Crystal data for (6): T= 170(2) K, a = 1685.89(9) pm, c = 3760.0(3) pm, V= 10686.9(11) x 10^6 pm^3 R1 for Fo > 4a(Fo) - 0.060, wR2 = 0.144.