Solid-state Zn-67 NMR spectra of model compounds for metallophoteins, such as [H2B(3,5-Me(2)pz)(2)](2)Zn (pz denotes pyrazolyl ring), have been obtained using low temperatures (10 K) to enhance the Boltzmann factor in combination with cross polarization (CP) from H-1 to Zn-67. Attempts to observe spectra of other model compounds, such as [H2B(pz)(2)](2)Zn, were hindered by long relaxation times of the protons. To decrease the proton relaxation times, the high-spin six-coordinate complex [HB(3,4,5-Me(3)pz)(3)](2)Fe has been investigated as a dopant. NMR and EPR measurements have shown that this Fe(II) dopant effectively reduces the H-1 spin lattice relaxation time, T-1, of the zinc samples in the temperature range 5-10 K with minimal perturbations of the H-1 spin lattice relaxation time in the rotating frame, T-1rho. Using this methodology, we have determined the Zn-67 NMR parameters of four- and six-coordinate zinc(II) poly(pyrazolyl) borate complexes that are useful models for systems of biological importance. The Zn-67 NMR parameters are contrasted to the corresponding changes in the Cd-113 NMR parameters for the analogous compounds. Further, these investigations have demonstrated that a temperature-dependent phase transition occurs in the neighborhood of 185 K for [HB(3,5-Me(2)pz)(3)](2)Zn; the other poly(pyrazolyl) borate complexes we investigated did not show this temperature-dependent behavior. This conclusion is confirmed by a combination of room-temperature high-field (18.8 T) solid-state Zn-67 NMR spectroscopy and low-temperature X-ray methods. The utilization of paramagnetic dopants should enable low-temperature cross polarization experiments to be performed on a wide variety of nuclides that are important in bioinorganic chemistry, for example, Mg-25, Ca-43, and Zn-67.