Crystallographic characterization of rare-earth cyanotriphenylborate complexes and the cyanoborates [NCBPh₃]¹⁻, [NCBPh₂Me]¹⁻, and [NCBPh₂(μ-O)BPh₂]¹⁻

Abstract

The investigation of the coordination chemistry of rare-earth metal complexes with cyanide ligands led to the isolation and crystallographic characterization of the Ln III cyanotriphenylborate complexes dichlorido(cyanotriphenylborato-κN)tetrakis(tetrahydrofuran-κO)lanthanide(III), [LnCl2(C19H15BN)(C4H8O)4] [lanthanide (Ln) = dysprosium (Dy) and yttrium Y)] from reactions of LnCl3, KCN, and NaBPh4. Attempts to independently synthesize the tetraethylammonium salt of (NCBPh3)− from BPh3 and [NEt4][CN] in THF yielded crystals of the phenyl-substituted cyclic borate, tetraethylazanium 2,2,4,6-tetraphenyl-1,3,5,2λ4,4,6-trioxatriborinan-2-ide, C8H20N+·C24H20B3O3 − or [NEt4][B3(μ-O)3(C6H5)4]. The mechanochemical reaction of BPh3 and [NEt4][CN] without solvent produced crystals of tetraethylazanium cyanodiphenyl-λ4-boranyl diphenylborinate, C8H20N+·C25H20B2NO− or [NEt4][NCBPh2(μ-O)BPh2]. Reaction of BPh3 and KCN in THF in the presence of 2.2.2-cryptand (crypt) led to a crystal of bis[(2.2.2-cryptand)potassium] 2,2,4,6-tetraphenyl-1,3,5,2λ4,4,6-trioxatriborinan-2-ide cyanomethyldiphenylborate tetrahydrofuran disolvate, 2C18H36KN2O6 +·C24H20B3O3 −·C14H13BN−·2C4H8O or [K(crypt)]2[B3(μ-O)3(C6H5)4][NCBPh2Me]·2THF. The [NCBPh2(μ-O)BPh2]1− and (NCBPh2Me)1− anions have not been structurally characterized previously. The structure of 1-Y was refined as a two-component twin with occupancy factors 0.513 (1) and 0.487 (1). In 4, one solvent molecule was disordered and included using multiple components with partial site-occupancy factors.