Platinum complexes featuring pyridine bis-N-heterocyclic-imidazol-2-ylidene/-mesoionic-triazol-5-ylidene donors as pincer ligands and chloro (-Cl), acetonitrile (-NCCH3) or cyano (-CN) groups as ...auxiliary ligands are prepared as highly strained organometallic phosphors. X-ray structures of four of these complexes confirm a distorted square planar geometry, where the pincer ligand and its mesityl wingtips occur in a twisted conformation to each other. Electrochemical and photophysical characterization have been carried out and the experimental results are interpreted with the aid of density functional theory calculations. Emission responses of complexes under exposure to different vapors and mechanical shear are reported. Notably, the platinum complex featuring pyridine bis-imidazol-2-ylidene and a weakly donating acetonitrile auxiliary ligand exhibited strong aquachromic and mechanochromic emission responses, showing color changes from sky blue to green or yellow-green.
By employing time-resolved Fourier transform infrared emission spectroscopy, the fragments HCl (v=1-3), HBr (v=1), and CO (v=1-3) are detected in one-photon dissociation of 2-bromopropionyl chloride ...(CH(3)CHBrCOCl) at 248 nm. Ar gas is added to induce internal conversion and to enhance the fragment yields. The time-resolved high-resolution spectra of HCl and CO were analyzed to determine the rovibrational energy deposition of 10.0±0.2 and 7.4±0.6 kcal mol(-1), respectively, while the rotational energy in HBr is evaluated to be 0.9±0.1 kcal mol(-1). The branching ratio of HCl(v>0)/HBr(v>0) is estimated to be 1:0.53. The bond selectivity of halide formation in the photolysis follows the same trend as the halogen atom elimination. The probability of HCl contribution from a hot Cl reaction with the precursor is negligible according to the measurements of HCl amount by adding an active reagent, Br(2), in the system. The HCl elimination channel under Ar addition is verified to be slower by two orders of magnitude than the Cl elimination channel. With the aid of ab initio calculations, the observed fragments are dissociated from the hot ground state CH(3)CHBrCOCl. A two-body dissociation channel is favored leading to either HCl+CH(3)CBrCO or HBr+CH(2)CHCOCl, in which the CH(3)CBrCO moiety may further undergo secondary dissociation to release CO.
Platinum complexes featuring pyridine bis-N-heterocyclic-imidazol-2-ylidene/-mesoionic-triazol-5-ylidene donors as pincer ligands and chloro (-Cl), acetonitrile (-NCCH
3
) or cyano (-CN) groups as ...auxiliary ligands are prepared as highly strained organometallic phosphors. X-ray structures of four of these complexes confirm a distorted square planar geometry, where the pincer ligand and its mesityl wingtips occur in a twisted conformation to each other. Electrochemical and photophysical characterization have been carried out and the experimental results are interpreted with the aid of density functional theory calculations. Emission responses of complexes under exposure to different vapors and mechanical shear are reported. Notably, the platinum complex featuring pyridine bis-imidazol-2-ylidene and a weakly donating acetonitrile auxiliary ligand exhibited strong aquachromic and mechanochromic emission responses, showing color changes from sky blue to green or yellow-green.
Platinum complexes featuring pyridine bis-N-heterocyclic imidazol-2-ylidene/triazol-5-ylidene donors are prepared and screened for vapo/mechanochromic attributes.
In this dissertation, quantum chemistry computational theory is used to study the electronic structure and properties of a number of polyatomic molecules and ions. Some general characteristics of ...this work are the use of molecular symmetry and the use of relativistic methods to enable the treatment of molecules containing heavy atoms. SYMCOE, a computer program for generating symmetry orbitals by the projection operator method, is described. Ab initio restricted Hartree-Fock calculations were performed on the ground states and excited states of C$\sb{60}$, C$\sbsp{60}{+}$, C$\sbsp{60}{-}$, C$\sbsp{60}{-2}$, and C$\sbsp{60}{-3}$. The photoelectron spectrum of C$\sb{60}$ was computed by the $\Delta$SCF method. Electron affinities and excitation energies were obtained. C$\sbsp{60}{-}$ was computed to be more stable than C$\sb{60}$. C$\sbsp{60}{-2}$ was estimated to be more stable than C$\sb{60}$ while C$\sbsp{60}{-3}$ was estimated to be higher in energy than C$\sb{60}$. Restricted Hartree-Fock ab initio calculations using relativistic core potentials were performed on C$\sb{60}$M (M = O, F, K, Ca, Mn, Cs, Ba, La, Eu, U) complexes with M as the central atom in the C$\sb{60}$ truncated icosahedron. The carbon cage accepted 0-2 electrons from the metals, and for the larger central atoms, the ionization potentials of these complexes are almost constant. The electronic structure of actinocene molecules, M(C$\sb8$H$\sb8$)$\sb2$ (M = U, Np, Pu), was studied by performing spin-orbit configuration-interaction calculations where relativistically derived core potentials were used. The magnetic moment of the Np(C$\sb8$H$\sb8$)$\sb2$ were also computed. The ground states of U(C$\sb8$H$\sb8$)$\sb2$, Np(C$\sb8$H$\sb8$)$\sb2$, and Pu(C$\sb8$H$\sb8$)$\sb2$ were calculated to have quantum number $\vert$M$\sb{\rm J}\vert$ = 3, 5/2, and 0, respectively. The visible absorption spectra of U(C$\sb8$H$\sb8$)$\sb2$ and Np(C$\sb8$H$\sb8$)$\sb2$ were found to be due to f $\to$ d transitions and that of Pu(C$\sb8$H$\sb8$)$\sb2$ was found to be due to $\pi\to$ d charge-transfer transitions.
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