BLUE COPPER PROTEINS - SYNTHESIS, CHEMISTRY, AND SPECTROSCOPY OF CUIN3(SR) AND CUIIN3(SR) ACTIVE-SITE APPROXIMATIONS - CRYSTAL-STRUCTURE OF POTASSIUM PARA-NITROBENZENETHIOLATO(HYDROTRIS(3,5-DIMETHYL-L-PYRAZOLYL)-BORATO)CUPRATE(I) DIACETONE, K[CU(HB(3,5-ME2PZ)3)-(SC6H4NO2)].2C3H6O

The cuprous complexes K[Cu(HB(3,5-Me2pz)3)(SR)] (SR = p-nitrobenzenethiolate or O-ethylcysteinate; HB(3,5-Me2pz)3= hydrotris(3,5-dimethyI-l-pyrazolyl)borate) can be prepared by the reaction of Cu(SR) or [Cu(SR)]-(CIO4) with KHB(3.5-Me2pz)3at room temperature. The structure of the complex with SR = p-nitrobenzenethiolate has been determined by X-ray diffraction methods. The complex crystallizes in the triclinic space group C1-P1 with two molecules in a unit cell of dimensions a = 10.60(2) Å, b = 18.17 (4) Å, c = 10.33 (4) Å, a = 93.57 (5)°,β = 116.20 (7)°, and γ = 71.89 (5)°. Least-squares refinement of the 117 variables has led to a value of the conventional R index (on F) of 0.092 for 678 independent reflections having F02>3σ(F02). The geometry about the Cu1 atom, which is coordinated to three nitrogen atoms and one sulfur atom, is trigonally distorted tetrahedral. The cupric complexes Cu(HB(3,5-Me2pz)3)(SR) (SR = p-nitrobenzene-thiolate or O-ethylcysteinate) have been prepared by the reaction of KHB(3,5-Me2pz)3with the corresponding [Cu(SR)]-(CIO4) derivatives at -78°C. UV-visible, laser Raman, and EPR data are used to show that the Cu1complexes have a very similar structure to that of the Cu1 complex characterized by X-ray diffraction methods. The Cu1complex Cu(HB(3,5-Me2pz)3(OR) (OR = p-nitrobenzenephenolate, OC6H4NO2) was prepared by the reaction of NaOC6H4NO2-2H2O with CuBr(HB(3,5-Me2pz)3in tetrahydrofuran at room temperature. The UV-visible, laser Raman, and EPR data for this complex are used in the interpretation of the spectra of the Cu11N3(SR) and Cu11N3(SR) complexes. The spectral properties of the Cu11N3(SR) complexes are similar to those of the blue (type 1) copper proteins and allow certain definite conclusions to be drawn concerning the origin of the distinctive UV-visible, resonance Raman, and EPR spectral features of the proteins. © 1979, American Chemical Society. All rights reserved.