A pseudotetrahedral nickel(II) complex with a tridentate oxazoline-based scorpionate ligand: chlorido[tris(4,4-dimethyloxazolin-2-yl)phenyl- borato]nickel(II)

摘要

Poly(pyrazol-1-yl)borates have been utilized extensively in coordination compounds due to their high affinity toward cationic metal ions on the basis of electrostatic interactions derived from the mononegatively charged boron centre. The original poly(pyrazol-1-yl)borates, christened 'scorpionates', were pioneered by the late Professor Swiatoslaw Trofimenko and have expanded to include various borate ligands with N-, P-, O-, S-, Se- and C-donors. Scorpionate ligands with boron-carbon bonds, rather than the normal boron-nitrogen bonds, have been developed and in these new types of scorpionate ligands, amines and azoles, such as pyridines, imidazoles and oxazolines, have been employed as N-donors instead of pyrazoles. Furthermore, a variety of bis- and tris(oxazolin-yl)borate ligands, including chiral ones, have been developed. Tris(oxazolin-2-yl)borates work as facially capping tridentate chelating ligands in the same way as tris(pyrazol-1-yl)borates. In the title compound, [Ni(C_21H_29BN_3O_3)Cl], the Ni~II ion is coordinated by three N atoms from the facially capping tridentate chelating tris(4,4-dimethyloxazolin-2-yl)phenylborate ligand and a chloride ligand in a highly distorted tetrahedral geometry. The Ni—Cl bond length [2.1851 (5) A] is comparable to those found in a previously reported tris(3,5-dimethylpyrazol-1-yl)hydroborate derivative [2.1955 (18) and 2.150 (2) A]. The molecular structure deviates from C_3v symmetry due to the structural flexibility of the tris(4,4-dimethyloxazolin-2-yl)phenylborate ligand.