Modeling the Metal Center of Cys4 Zinc Proteins

We present here a 67Zn solid-state NMR investigation of several model complexes of zinc coordinated by four sulfurs. The lineshapes were obtained at a variety of magnetic fields from 11.7 T (500 MHz for 1H) to 21.15 T (900 MHz for 1H) and at ambient temperature down to 10 K. The quadrupole coupling constants, C q's, ranged from 3.25 to 16.7 MHz throughout the series, while the average bond distances only spanned 2.34−2.36 Å. Reasonable agreement with experiment was achieved in the molecular orbital calculations using DFT methods and the local density approximation to predict electric field gradients.