Quantum & Physical Chemistry Computational Coordination Chemistry HARDWARE Did you know that:  The quantum mechanical wave equations can nowadays be solved for molecules with a precision that often surpasses experimental accuracy ?  Calculations on molecules have become an integrated part of chemical and physical research ? SOFTWARE: GAUSSIAN, MOLCAS, TURBOMOLE, ADF, MOLPRO, GAMESS, Constitute a range of programs capable of handling both DFT (up to ~1000 atoms) and highly correlated calculations (up to ~100 atoms )  Do you like chemistry at a conceptual level ?  Do you want to get insight into the electronic structure of the molecules you are studying?  Do you like computers ? Both the hardware and software are shared between the research groups computational coordination chemistry and quantum chemistry Research topics: Many transition metal ions occur as active centers in enzymes, in a coordination environment built from very specific and often quite complicated ligands (e.g. the porphyrin group in iron heme proteins). These ligands serve to provide the transition metal with the specific electronic structure that is crucial for its catalytic task in the enzyme. However, quite often the details of this electronic structure are not yet known: How are the electrons divided over the metal d orbitals ? What is the spin of the ground state ? How strong is the ligand field exerted by the ligands ? What is the character of the metal-ligand bonds: ionic or covalent ? How high in energy are the lowest excited states ? Can they play a role in the catalytic activity of the metal ? What is their nature (ligand field or charge-transfer ?) Experimentally, information concerning these questions is most often obtained from spectroscopic measurements: electronic absorption or emission, magnetic circular dichroism (MCD), electron spin resonance (ESR) spectroscopy. A more direct answer may be obtained from theoretical calculations. The results of these calculations also serve to interpret the experimental spectra. Computational investigation of the electronic structure of transition metal centers in enzymes. It is possible to make a thesis in the framework of these two topics. Furtherrmore, should you be interested in computational method development, subjects is this area can also be discussed. Our research group is also involved in ERASMUS exchange programs with Lund (Sweden) and Valencia (Spain) Traditional transition metal complexes are built from coordinative bond formation between a metal with an open d shell on the one hand and a number of closed-shell ligands on the other hand. The latter are so-called innocent ligands, e.g., OH 2, NH 3, CN -, CO. They participate in the bond by donating an electron pair to the metal. Non-innocent ligands are radicals: their HOMO contains a single electron. A simple example is NO. Coordinative bonds can only be formed with the cation, NO + (giving rise to a linear bond). However, another possibility is that a bond is formed by spin coupling between the single electron on NO and an unpaired electron on the metal (giving rise to a bend bond). By means of computations on different low-lying states in complexes with non-innocent ligands, NO or more complex ligands such as e.g. the o-iminobenzosemiquinonato radical, we hope to obtain more profound insight into these unconventional bonds. Contact details: o Kristin Pierloot ( room 03.15; tel 016 o Steven Vancoillie ( room 03.74; tel: 016 Transition metal complexes with non-innocent ligands: where are the unpaired electrons ? or Fe(II) tetraphenyl- Porphin? Fe(III) + NO Fe(II) + NO + ?