Chemical Bonding Paradigms And Implications On Reactivity Of Homobimetallic Carbido Complexes

Abstract

Abstract newlineChemical bonding models have been a pivotal component in the development of modern chemistry. It has contributed to a credible pool of scientific knowledge along with providing compelling inspiration and evidence for the experimental pursuits of molecules with exquisite structural and electronic attributes. The continuously developing chemistry of carbon compounds is a prototype to truly comprehend the above statements. Carbon atom (3P; 2s2 2pz1 2px1 2py0) is known to exhibit a wide variety of coordination viz. hypercoordinate, planar tetra coordinate, dicoordinate to terminal monocoordinate bonding modes. While the dicoordinate carbenes and carbones mostly employ main group substitution adjacent to the carbon centre, a complimentary and large class of dicoordinate carbon compounds feature a carbon atom sandwiched between two transition metal fragments (TM). Such and#956;-carbido complexes are broadly classified into three categories i) metallacarbyne; ii) organometalliccumulene/allene type, and iii) bent metallacarbene. The structure, bonding and reactivity of the latter two categories are not well established, and form the prime focus of this thesis. We have carried out electronic structure, bonding and reactivity studies of selected homobimetallic and#61549;-carbido complexes within the density functional formalism at the M06/def2-TZVPP//BP86/def2-SVP level of theory. Quantitative bonding analysis using energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) method has been carried out at BP86/TZ2P level. newlineThe first part of the thesis investigates the bonding in organometallic allenes and their heavier analogues, and establish their complex relationship with the organic allene C(CH2)2. The organometallic allenes are seen to show structural variety depending upon the electronic and geometrical attributes of the terminal transition metal fragment.