⁶³Cu FT-NMR Studies of Tetrahedral Copper(I)-Phosphorus Complexes

Abstract

Tetrahedrally coordinated copper(I) complexes C11L4X have been synthesized, L being P(OR)3, PR3 or P(R)n(OR)3-n, and X being a non-coordinating anion such as Perchlorate or tetrafluoroborate. Depending on the nature of the bound phosphorus ligand the Cu(I) complexes give well resolved 63 Cu NMR spectra including a quintet signal due to spin-spin coupling between 63 Cu and 31 P. The 63 Cu NMR spectra have been analyzed with reference to the chemical shift (), the shielding constant a* (given on an absolute atomic scale), the linewidth Av, and the coupling constant J( 63 Cu-31 P). Generally, the relative magnitude of these NMR parameters are in satisfactory agreement with results reported for isoelectronic Ni(O) complexes with the phosphorus ligands mentioned above. Furthermore, the NMR properties of the Cu(I) compounds are discussed in terms of cr-donor or 7r-acceptor capacities of the ligands coordinated, and stereochemical properties of the complexes.

Copper(I) Complexes of a Flexible Bis-phospholane Ligand: Route to Paddle-Wheel- and Box-Type Macrocycles

“…Because phospholane is a better σ donor than triphenylphosphine, a 1 J PCu value of ∼775 Hz is consistent with reported trends. By comparison, the reported 1 J PCu value for [Cu­{P­(OCH 3 ) 3 } 4 ]­ClO 4 is 1223 Hz . A 63 Cu­{ 1 H} NMR spectrum of complex 3 was also recorded and correlates well with the results obtained from the 31 P­{ 1 H} NMR spectrum (see Supporting Information).…”

“…It shows a broad quintet at 284.2 ppm with a 1 J CuP value of 780 Hz, a more precise value than that obtained from the 31 P­{ 1 H} NMR spectrum. The signal pattern is in agreement with published data . Even though the ESI­(+) mass spectrum of 3 shows only fragmentation peaks, the 31 P­{ 1 H} and 63 Cu NMR spectra indicate that the box-type structure is retained in solution.…”

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

“…35 Consequently only complexes with regular tetrahedral or cubic symmetry are NMR active. 36 We have chosen to use mainly 63 Cu NMR spectroscopy to be able to make comparisons with previous studies. 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.…”

“…Neither 63 Cu nor 65 Cu NMR signals could be observed from the complexes of copper() in triphenyl phosphite and tri-n-butylphosphine in spite of cooling. The absence of NMR signals for some of the copper() phosphite species have earlier been explained by equilibria with two-or three-coordinated species, 36 and large ligand cone angles 25 have been considered to cause steric hindrance within regular T d symmetry. The absence of NMR signals strongly indicates that the configuration around copper() deviates significantly from a regular tetrahedron.…”

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

“…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. ,, …”