Nitridokomplexe von Molybdän(V); Synthesen, IR- und EPR-Spektren. Die Kristallstruktur von [Na(15-Krone-5)Na(THF)]2[MoNCl3 ·THF]4·2THF / Nitrido Complexes of Molybdenum(V); Syntheses, IR, and EPR Spectra. Crystal Structure of [Na(15-Crown-5)Na(THF)]2[MoNCl3·THF]4·2THF

Abstract

The molybdenum nitrido complexes [Na(15-crown-5)][MoNCl3] (1), [Na(15-crown-5)]2[MoNCl4] (2), and [Na(15-crown-5)Na(THF)]2[MoNCl3·THF]4·2THF (3) have been prepared by reactions of MoNCl3 with sodium naphthalide in tetrahydrofurane (THF) in the presence of 15-crown-5. According to the EPR spectra and in agreement with the IR spectra, 1 forms dimeric ions [MoNCl3]2 2~ via chloro bridges, whereas tetrameric units [MoNCl4]4 8~ and [MoNCl3 · THF]4 4~ are present in 2 and 3, respectively. 3 was characterized by an X-ray structure determination: space group P21/c, Z = 2, 1964 observed unique reflexions, R = 0.12. Lattice dimensions at —90 °C: a = 1173(1); b = 2083(3); c = 1750(2) pm; β = 112.3(7)°. The structure consists of an ensemble of associated ions around the central [MoNCl3 ·THF]4 4~ unit. In the latter, the four Mo atoms form a square and are bridged via linear, asymmetric Mo=N—Mo groups. The (MoN)4 square is enclosed in a cube of eight Cl atoms, the Mo atoms occupying four of the cube edges. Two Na+ ions are situated in the centres of two opposing cube faces, each of the other two Na+ ions is coordinated with two Cl atoms outside of the cube; these Na+ ions are also coordinated with one THF molecule and with one 15-crown-5 molecule, respectively. The crystal also contains non-coordinated THF molecules, which exhibit strong thermal motion and/or disorder.