Département de chimie moléculaire

Herein, Ca K-edge x-ray absorption spectroscopy (XAS) is developed as a means to characterize the local environment of Ca centers. The spectra for 6, 7, and 8 coordinate inorg. and mol. Ca complexes were analyzed and are primarily influenced by the coordination environment and site symmetry at the Ca center. The exptl. results are closely correlated to time-dependent d. functional theory (TD-DFT) calcns. of the XAS spectra. The applicability of this methodol. to complex systems was studied using structural mimics of the O-evolving complex (OEC) of PSII. Ca K-edge XAS is a sensitive probe for structural changes occurring in the cubane heterometallic cluster due to Mn oxidn. Future applications to the OEC are discussed. Crystallog. data are given. [on SciFinder(R)]