Synthesis and Spectroscopic Properties of Cobalt(II), Copper(I), and Silver(I) Complexes and Crystal Structure of a Cobalt(II) Complex with a Bidentate Diisonitrile Containing Two Amino Nitrogens in the Bridging Group

Abstract

The diisonitrile (L2), which includes two amino nitrogens in the bridging group, has been synthesized in six reaction steps from chlorobenzene. The reaction of cobalt(II) bromide hexahydrate or silver(I) tetrafluoroborate with L2 leads to the corresponding complexes, CoBr2L2 2 and AgL2 2BF4, whereas the copper(I) complex, CuL2 2BF4, is prepared by a ligand exchange reaction of tetrakis(acetonitrile)copper(I) tetrafluoroborate. By the usage of the molar conductances and mass spectra, tetrafluoroborates in CuL2 2BF4 and AgL2 2BF4 are ionized. The crystal structure of CoBr2L2 2 was determined by a single‐crystal X‐ray diffractometry. The crystal system of the trans six‐coordinate diisonitrile cobalt(II) complex is reported for the first time. The crystal analysis of CoBr2L2 2 shows that it adopts an octahedral geometry in which two Br groups are in trans positions. The bond lengths of Co–C and Co–Br are 1.888 and 2.7146 Å, respectively. Judging from the IR and NMR spectra and single‐crystal X‐ray diffractometry, the N≡C group in the complexes serves as a σ‐donor and the amino nitrogens in the bridging group are not coordinated to the metal. Hence, the structure of the cobalt(II) complex is a hexa‐coordinated pseudo‐octahedron with two trans bromides.