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

Abstract

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.

Preparation of Energetic Poly(azolyl)borates as New Environmentally Benign Green‐Light‐Emitting Species for Pyrotechnics

“…The Raman spectrum exhibits bands attributable to the boron‐hydrogen stretching vibration at 2409 cm –1 , which is similar to values in complexes containing bis(pyrazolyl)borate ligands33 or hydridopoly(azolyl)borates in general. [22, 24, 25, 29, 34, 35] In the region between 3141 cm –1 and 3084 cm –1 the C–H stretching vibration of the nitroimidazole moiety is clearly visible, as well as the NO 2 asymmetric and symmetric valence vibrations found in the range between 1490–1545 cm –1 and 1315–1375 cm –1 , respectively 25,26,34,35. As expected from the obtained NMR spectroscopic data no traces of boric acid can be found.…”

“…The Raman spectrum shows the clear evidence of the BH 2 fragment by exhibiting a band at 2449 cm –1 which is characteristic for boron–hydrogen stretching vibrations in comparable complexes. [22, 24, 25, 29, 33–35] At 3140 cm –1 the band corresponding to the C–H stretching vibration of the imidazole moiety is visible as well as the NO 2 asymmetric and symmetric valence vibrations found in the range between 1490–1564 cm –1 and 1301–1375 cm –1 , respectively 25,26,34,35. As already mentioned, small residues of acetonitrile remained in the solid product and the corresponding bands are displayed in the Raman spectrum [pure acetonitrile: 2943 (100), 2253 (73), 921 (26), 382 (20) cm –1 ;44 acetonitrile residues: 2944 (10), 2266 (4), 955 (3), 388 (2) cm –1 ].…”

“… Dihydridobis(3‐nitro‐1, 2, 4‐triazolyl)borate ( 1 ),23 dihydridobis(3, 5‐dinitro‐1, 2, 4‐triazolyl)borate ( 2 ),24 dihydridobis (3‐nitropyrazolyl)borate ( 3 ),25 and hydridotris(3‐nitropyrazolyl) borate ( 3 )26 anions. …”

Synthesis, Characterization, and Crystal Structures of Scorpionate Complexes with the Hydrotris[3‐(2′‐thienyl)pyrazol‐1‐yl]borate Ligand

“…The dimensions within the two independent substrate molecules differ only trivially (Table 2) (Table S3, Supporting Information). [36][37][38][39][40][41][42] The presence of the Tn substituents apparently has little impact on the manner of coordination of the tridentate ligand or on the approach and coordination of the phosphine ligand. In both forms (i.…”

Characterization of Cu-ligand bonds in tris-pyrazolylmethane isocyanide copper(I) complexes based upon combined X-ray diffraction and theoretical study

“…Current progress in the synthesis of (RNC)Cu I compounds allows the classification of the reported species to the following types, viz. homoleptic species [Cu(CNR) n ] + (n = 3 and 4) [29,30] and mixed-ligand complexes bearing, apart isocyanide ligand(s), different C- [31][32][33], N- [34][35][36][37], X-(X = halogen) [38] and other donor ligands [39,40]. To the best of our knowledge, no theoretical studies focused on elucidation of ligand properties and activation of RNC species by copper(I) centers are known.…”