title: Syntheses, Structures, and Reactivity of Polynuclear Pyrazolato Copper(I) Complexes, Including an ab-Initio XRPD Study of [Cu(dmnpz)](3) (Hdmnpz = 3,5-Dimethyl-4-nitropyrazole).
abstract: The reaction of [Cu(CH(3)CN)(4)](BF(4)) with 3,5-dimethyl-4-nitropyrazole (Hdmnpz) in the presence of triethylamine yields the new copper(I) complexes [Cu(dmnpz)](3) (1) and (Et(3)NH)(2)[Cu(4)(dmnpz)(6)] (2), depending on the experimental conditions. The reactivity of 1 and 2 toward neutral ligands such as triphenylphosphine, cyclohexyl isocyanide (RNC), and carbon monoxide has been investigated. In particular, both complexes readily react with RNC, giving the dinuclear complexes [Cu(dmnpz)(RNC)](2) (4) and [Cu(dmnpz)(RNC)(2)](2) (5), depending on the copper/RNC ratio, and with PPh(3), affording the dimeric derivative [Cu(dmnpz)(PPh(3))](2) (6). The crystal and molecular structure of 1 has been determined ab initio using X-ray powder diffraction data from conventional laboratory equipment. Crystals of 1 are monoclinic, C2/c, a = 20.057(2) Å, b = 13.816(2) Å, c = 7.883(1) Å, beta = 95.912(4) degrees; R(F) and R(wp) 0.067 and 0.039, respectively, for Rietveld refinement on 3900 data points collected in the range 17 < 2theta < 95 degrees (Cu Kalpha radiation). Crystals of 1 contain planar trimers, with the copper atoms bridged by exo-bidentate ligands and short intermolecular Cu.Cu contacts (3.329(7) Å). For complexes 2 and 4-6, single-crystal X-ray diffraction studies have been performed. Crystals of 2 are monoclinic, P2(1)/c, a = 11.026(1) Å, b = 13.456(2) Å, c = 18.668(5) Å, beta = 92.91(2) degrees, Z = 2. The ionic packing of 2 contains tetranuclear complexes, with the copper atoms connected by six dmnpz ligands. Crystals of 4 are triclinic, P&onemacr;, a = 7.418(1) Å, b = 9.780(1) Å, c = 11.177(3) Å, alpha = 109.61(2); beta = 101.34(3) degrees, gamma = 105.82(1) degrees, Z = 2. Crystals of 5 are triclinic, P&onemacr;, a = 9.506(4) Å, b = 9.957(2) Å, c = 11.658(4) Å, alpha = 86.73(2) degrees, beta = 79.54(2) degrees, gamma = 82.47(4) degrees, Z = 1. Crystals of 6 are triclinic, P&onemacr;, a = 11.379(2) Å, b = 13.592(2) Å, c = 14.409(3) Å, alpha = 81.22(1) degrees, beta = 85.21(1) degrees, gamma = 87.55(1) degrees, Z = 2. 4, 5, and 6 are binuclear complexes bearing one RNC, two RNC, and one triphenylphosphine ligands on each copper atom, respectively. The steric requirement of the dmnpz ligands, in the presence of RNC or PPh(3), forces the inner [Cu(2)(dmnpz)(2)] core of the three complexes into markedly different conformations.
authors.affiliation: Dipartimento di Chimica Inorganica, Metallorganica e Analitica, and Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Centro CNR, Università di Milano, Via Venezian 21, I-20133 Milano, Italy.
authors.forename: G. Attilio
authors.initials: GA
authors.lastname: Ardizzoia
authors.forename: Sergio
authors.initials: S
authors.lastname: Cenini
authors.forename: Girolamo
authors.initials: G
authors.lastname: La Monica
authors.forename: Norberto
authors.initials: N
authors.lastname: Masciocchi
authors.forename: Angelo
authors.initials: A
authors.lastname: Maspero
authors.forename: Massimo
authors.initials: M
authors.lastname: Moret