Scorpionates bearing nitro substituents: mono-, bis- and tris-(3-nitro-pyrazol-1-yl)borate ligands and their copper(i) complexes

Two scorpionates sodium trihydro(3-nitro-pyrazol-1-yl)borate (Na[H(3)B(3-(NO(2))pz)]) and sodium hydrotris(3-nitro-pyrazol-1-yl)borate (Na[HB(3-(NO(2))pz)(3)]), featuring electron withdrawing substituents, have been synthesized in high yield starting from 3(5)-nitropyrazole and sodium borohydride. The treatment of CuX (X = (CH(3)CN)(4)PF(6), Cl or I) with Na[H(3)B(3-(NO(2))pz)], Na[HB(3-(NO(2))pz)(3)] or the related bis(pyrazolyl)borate Na[H(2)B(3-(NO(2))pz)(2)] in the presence of triphenylphosphine or tert-butyl isocyanide afforded the corresponding (azolyl)borate supported copper(I) triphenylphosphine or tert-butyl isocyanide adducts. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear NMR spectroscopy. X-Ray crystal structures of [H(3)B(3-(NO(2))pz)]Cu[P(C(6)H(5))(3)](2), [H(2)B(3-(NO(2))pz)]Cu(CNt-Bu)(2), and [HB(3-(NO(2))pz)(3)]Cu[P(C(6)H(5))(3)], as well as that of the {[HB(3-(NO(2))pz)(3)]Na}(4) are also reported. The latter displays a particularly interesting tetrameric structure with each tris(pyrazolyl)borate adopting an unusual inverted configuration and serves as a bridging ligand for three different sodium ions.