Executive Summary : | Activation of small molecules (CO₂, H₂, O₂, H₂O) by catalysis is at the heart of chemistry and vital for greener energy in storage and activation of hydrogen gas, for an environment in mitigation of CO₂, and for the synthesis of fine chemicals and chiral drug molecules. Consequently, the design and preparation of sustainable catalysts which can activate small molecules are highly desirable. Although the early main group, namely frustrated Lewis pairs (FLPs), have been used for the activation of small molecules, however, late main groups organochalcogens have not been studied. The late main group elements (MGEs) elements are more electronegative than the early MGEs and thus expected to favor redox cycling in catalytic reactions involving small molecules. Further, heavier main group elements offer a favorable energy gap (less than 4 eV) due to substantial mixing of bonding, HOMO with unoccupied non/anti-bonding orbitals because of weaker bonding involved in the molecules. A HOMO-LUMO energy gap of ≤4 eV is characteristic of many TM-catalysts and is crucial for activating small molecules by donating and accepting electrons to and from anti-bonding and bonding MOs, respectively. Nonetheless, activation of small molecules by the late MGEs is difficult due to the sufficient valence electrons and unavailability of a vacant coordination site, which is very much required for the initiation step in the activation of small molecules. It is difficult to stabilize organoselenium having Se(VI) oxidation state because of the un-stability of the highest oxidation state of Se attributed to periodic anomalous behavior of period 4th elements (Ga, Ge, As, Se, Br) as they appear after the filling of 3d-orbital in Zn for the first time and experience in contraction in size and high ionization energy. Because of the thermodynamic un-stabilty of Se(VI), organoselenium(VI) compounds serve as good oxidizing agents as they decompose or reduce to Se(IV) or Se(II). However, if organoselenium(VI) can be synthesized and stabilized, it could serve as a promising catalyst for many synthetic reactions and activation of small H₂ and CO₂ molecules because selenium, in its highest oxidation state, is highly Lewis acidic as it bears a high positive charge and could have HOMO-LUMO energy gap of ≤4 eV. Consequently, it interacts with small molecules and consequently activates them in a catalytic manner in synthetic transformation and could be explored in asymmetric transformations; when embedded with a chiral auxiliary. In this proposal, a new synthetic design for stabilizing unstable hexavalent organoselenium, which will exhibit diverse properties by activating small molecules, chiral Lewis acidic organo-catalyst, towards asymmetric transformations, has been proposed. The successful outcome of the proposal will lead to a new avenue in main-group chemistry for catalysis and result in several high-impact international journals and a couple of patents. |