Borotropic shifting of the [hydrotris(2 ′ -furyl)pyrazol-1-yl]borate ligand in high-coordinate lanthanide complexes

The coordination of hydrotris[3-(2 ′ -furyl)pyrazol-1-yl]borate (Tp2-Fu, C21H16BN6O3) to lanthanide(III) ions is achieved for the first time with the complex [Ln(Tp2-Fu)2](BPh4) · xCH2Cl2 (1-Ln has Ln   = Ce and x   = 2; 1-Dy has Ln   = Dy and x   = 1). This was accomplished via both hydrous (Ln   = Ce) and anhydrous methods (Ln   = Dy). When isolating the dysprosium analogue, the filtrate produced a second crop of crystals which were revealed to be the 1,2-borotropic-shifted product [Dy( κ 4-Tp2-Fu)( κ 5-Tp2-Fu*)](BPh4) (2) {Tp2-Fu*   = hydrobis[3-(2 ′ -furyl)pyrazol-1-yl][5-(2 ′ -furyl)pyrazol-1-yl]borate}. We conclude that the presence of a strong Lewis acid and a sterically crowded coordination environment are contributing factors for the 1,2-borotropic shifting of scorpionate ligands in conjunction with the size of the conical angle with the scorpionate ligand.
Source: Acta Crystallographica Section C - Category: Chemistry Authors: Tags: crystal structure lanthanide high-coordinate borotropic shifting icosahedral dysprosium cerium scorpionate research papers Source Type: research