63 Cu NMR Studies of Copper (I) Complexes in Solution: Influence of Anion, Solvent and Temperature on the Linewidth and Chemical Shift of the Copper Resonance

Abstract

The behaviour of the

63Cu NMR Study of Copper(I) Carbonyl Complexes with Various Hydrotris(pyrazolyl)borates: Correlation between63Cu Chemical Shifts and CO Stretching Vibrations

“…As discussed above, no significant structural difference has been observed for the alkyl and phenyl substituted complexes. Kroneck and co-workers reported the dependence of the line width on temperature and solvents …”

“…The nuclear spin of 63 Cu ( I = 3 / 2 ) accelerates the quadrupole relaxation of copper(I) in a lower symmetrical environment. For example, some CuL 4 type tetrahedral complexes show well-shaped signals with narrow line width. − But digonal and trigonal copper(I) species usually cannot be detected by 63 Cu NMR, and even CuL 3 L‘ type tetrahedral complexes give very broad resonance lines because of the reduced symmetry. ,, …”

The coordination chemistry of copper(i) in liquid ammonia, trialkyl and triphenyl phosphite, and tri-n-butylphosphine solution

“…The line widths of the 63 Cu NMR signals are, in addition to the quadrupole moment effects, solvent and anion dependent, and also dependent on the presence of water and copper(), both of them broadening the line width. 16 Furthermore, the line widths have been found to increase with temperature and linearly with the viscosity. 37 The 63 Cu and 65 Cu NMR spectra were recorded at 106.05 and 113.63 MHz, respectively, on a Bruker 400 DRX spectrometer equipped with a multinuclear BBO probe.…”

“…The chemical shifts are rather constant in the different solvents, as expected (Table 3). 16 The tetrakis(trialkyl phosphite)copper() complex showing a 63 Cu NMR signal with the highest density of electrons around the copper() nucleus (δ = Ϫ15) is [Cu(P(OCH(CH 3 ) 2 ) 3 ) 4 ] ϩ and the one with the lowest electron density (δ = 3) is [Cu((OC 4 H 9 ) 3 ) 4 ] ϩ . The tetrakis(triisopropyl phosphite)copper() complex does show a slightly longer Cu-P bond distance, while the other complexes have essentially the same Cu-P bond lengths (Table 2).…”

“…The line broadening effects are 2% when 1% of the copper is present as copper(), while an increase in the copper() content to 9% results in a line broadening effect of 870%. 16 A single crystal X-ray determination of [Ag(NH 3 ) 3 ]NO 3 , crystallised from liquid ammonia, reveals a three-coordination around silver with a Ag-N bond distance of 2.281(7) Å. 7 A single crystal X-ray determination of the corresponding copper() complex precipitated from liquid ammonia was not possible to perform, but the authors stated that Guinier data reveal that the nitrate salts of the ammonia solvated copper() and silver() complexes are isostructural (same space group and similar unit cell parameters).…”