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Maximum overlap methods are effective tools for optimizing challenging ground‐ and excited‐state wave functions using self‐consistent field models such as Hartree‐Fock and Kohn‐Sham density functional theory. Nevertheless, such models have shown significant sensitivity to the user‐defined initial guess of the target wave function. In this work, a projection operator framework is defined and used to provide a metric for non‐aufbau orbital selection in maximum‐overlap‐methods. The resulting algorithms, termed the Projection‐based Maximum Overlap Method (PMOM) and Projection‐based Initial Maximum Overlap Method (PIMOM), are shown to perform exceptionally well when using simple user‐defined target solutions based on occupied/virtual molecular orbital permutations. This work also presents a new metric that provides a simple and conceptually convenient measure of agreement between the desired target and the current or final SCF results during a calculation employing a maximum‐overlap method.

 

We report a new method for regioselective aromatic bromination using lactic acid derivatives as halogen bond acceptors with N-bromosuccinimide (NBS). Several structural analogues of lactic acid affect the efficiency of aromatic brominations, presumably via Lewis acid/base halogen-bonding interactions. Rate comparisons of aromatic brominations demonstrate the reactivity enhancement available via catalytic additives capable of halogen bonding. Computational results demonstrate that Lewis basic additives interact with NBS to increase the electropositive character of bromine prior to electrophilic transfer. An optimized procedure using catalytic mandelic acid under aqueous conditions at room temperature was developed to promote aromatic bromination on a variety of arene substrates with complete regioselectivity.