Di-and Trinuclear Complexes with the Mono-and Dianion of 2,6-Bis(phenylamino)pyridine:High-Field Displacement of Chemical Shifts Due to the Magnetic Anisotropy of Quadruple Bonds

摘要

The monoanion of 2,6-bis(phenylamino)pyridine (HBPAP~-)has been found to support quadruply bonded Cr_2~(4+) and Mo_2~(4+)units in Cr_2(HBPAP)_4(1) and Mo_2(HBPAP)_4(2).The corresponding dianion BPAP~(2-)was able to stabilize the trinuclear complexes,(TBA)_2Cr_3(BPAP)_4(3)and (TBA)_2Ni_3(BPAP)_4(4), where TBA is the tetrabutylammonium cation. The dinuclear complexes have the typical paddlewheel configuration with Cr-Cr distances of about 1.87A and a Mo-Mo distance of 2.0813(5)A and exhibit a high-field displacement of the corresponding N-H signals caused by the magnetic anisotropy of the quadruple bonds.For the trinuclear complexes,3 has a linear chain of three chromium atoms arranged in an unsymmetrical fashion with two chromium atoms paired to give a quadruply bonded unit (Cr-Cr distance:1.904(3)A)and an isolated, square planar Cr_II unit at 2.589(3)A from the dimetal unit. On the other hand, the three nickel atoms in 4 are evenly spaced, having Ni…Ni distances of 2.3682(8)A. The trinuclear compounds show a twisted conformation with an overall torsion angle of about 30dge.