The resonance Raman (RR) spectra of blue copper proteins are unusually complicated, with at least five bands in the 400-cm-1 region. To explore the sources of this complexity we have examined RR spectra of LCuSR complexes [L = hydrotris(3,5-diisopropyl-1-pyrazolyl)borate], which are known to be close structural and electronic analogs of the blue Cu site. When the C atom which is attached to the S atom lacks a proton, a single prominent band is seen near 430 cm-1, assignable to the stretching mode of a short (ca. 2.1 angstrom) Cu-S bond, which is characteristic of the blue Cu site, and of the model complexes. The frequency decreases in the order R = tert-butyl > triphenylmethyl > pentafluorophenyl, consistent with the expected effect of increasing electron withdrawal on the Cu-S bond strength. Weaker bands are seen at lower frequencies, which are attributed to thiolate internal bending and to Cu-N[pyrazole] stretching coordinates. These assignments were confirmed with a normal coordinate analysis for the tert-butylthiolate complex, which accurately reproduced the frequencies and isotope shifts for perdeuteration of the tert-butyl substituent. When R = sec-butyl, three prominent bands are seen in the 400-cm-1 region instead of one. Normal mode analysis shows extensive mixing of Cu-S stretching with C-C-S and C-C-C bending coordinates in these three modes, occasioned by the inequivalences in the bending coordinates and the involvement of HC-CH torsion. Implications for the blue copper protein RR spectra are discussed.