Solid-State ~(63)Cu and ~(65)Cu NMR Spectroscopy of Inorganic and Organometallic Copper(Ⅰ) Complexes

摘要

Solid-state ~(63)Cu and ~(65)Cu NMR experiments have been conducted on a series of inorganic and organometallic copper(l) complexes possessing a variety of spherically asymmetric two-, three-, and four-coordinate Cu coordination environments. Variations in structure and symmetry, and corresponding changes in the electric field gradient (EFG) tensors, yield ~(63/65)Cu quadrupolar coupling constants (C_q) ranging from 22.0 to 71.0 MHz for spherically asymmetric Cu sites. These large quadrupolar interactions result in spectra featuring quadrupolar-dominated central transition patterns with breadths ranging from 760 kHz to 6.7 MHz. Accordingly, Hahn-echo and/or QCPMG pulse sequences were applied in a frequency-stepped manner to rapidly acquire high SIN powder patterns. Significant copper chemical shielding anisotropies (CSAs) are also observed in some cases, ranging from 1000 to 1500 ppm. ~(31)P CP/MAS NMR spectra for complexes featuring ~(63/65)Cu-~(31)P spin pairs exhibit residual dipolar coupling and are simulated to determine both the sign of C_q and the EFG tensor orientations relative to the Cu-P bond axes. X-ray crystallographic data and theoretical (Hartree-Fock and density functional theory) calculations of ~(63/65)Cu EFG and CS tensors are utilized to examine the relationships between NMR interaction tensor parameters, the magnitudes and orientations of the principal components, and molecular structure and symmetry.