| The objective of the work presented in this thesis has been to make a contribution to the frontier field of photo-crystallography by carrying out Density Functional Theory investigation of transient excited states in relatively large molecular transition metal complexes. The challenges associated with this objective are applicability of Density Functional Theory (originally a ground-state method) vs conventional ab initio correlated methods to study the excited states in molecular systems, and the computational effort connected with first-principle quantum mechanical studies on large systems: until recently calculations on such systems have been difficult (even with DFT), and only the use of super-computer power has made our goals possible. We have successfully modeled and described geometrical and electronic structures of photo-induced transient states in several transition metal complexes: [Ru(NH 3)4(NO)L]n+, [RuCl4(NO)L] n−, [RuCl4(CO)(H2O)]1−, biologically relevant FeP′(NO), d8-d 8 bi-nuclear platinum(II) [Pt2(H2P2O 5)4]4− and rhodium(I) [Rh2(1,3-diisocyanopropane) 4]2+ compounds. The purpose is to provide a foundation for accurate, qualitative description of the structure and energetics of the excited states of these complexes, and in particular, a better understanding of the nature and behavior of these molecular systems which play an important role in photochemical reactions. |
