Syntheses and characterization of new (pyrazolato)(pyrazole) rutheniums with κ3-polypyrazolylborates: Halogeno-anion binding through the tris(pyrazole) moiety

(Polypyrazolylborato)(benzonitrile) ruthenium(II) complexes [RuCl{BR(pz)3}(PhCN)2] (R = pz, H; pz = pyrazol-1-yl), prepared from trans-[RuCl2(PhCN)4] and K[BR(pz)3], were allowed to react with potassium 3,5-dimethyl-substituted polypyrazolylborate salt K[BH(3,5-Me2pz)3], and gave (pyrazolato)(pyrazole) species of [Ru{BR(pz)3}(3,5-Me2pz)(3,5-Me2pzH)2] {R = pz (1), H (2)}, respectively. Upon protonation with HBF4 (Et2O), the species 1 was converted to a fairly stable tris(pyrazole) derivative [Ru{B(pz)4}(3,5-Me2pzH)3]BF4 (3), which worked as a novel halogeno-anion receptor. Moreover, the complex [RuCl2(PhCN)4] was treated with K[BH(3,5-Me2-4-Brpz)3] in the presence of 3,5-dimethyl-4-bromopyrazole, 3,5-Me2-4-BrpzH, to afford [Ru{BH(3,5-Me2-4-Brpz)3}(3,5-Me2-4-Brpz)(3,5-Me2-4-BrpzH)2] and [Ru{BH(3,5-Me2-4-Brpz)3}(3,5-Me2-4-Brpz)(3,5-Me2-4-BrpzH)(PhCN)]. Single-crystal X-ray structural analyses were carried out for 1, 3 · CHCl3, [Ru{B(pz)4}(3,5-Me2pzH)2(OH2)]O3SC6H4CH3 · CH3OH, and [RuCl{B(pz)4}(3,5-Me2pzH)2] · CHCl3.