Metal-Only Lewis Pairs with Transition Metal Lewis Basas

2153 WordsFeb 20, 20189 Pages
Metal-Only Lewis Pairs with Transition Metal Lewis Basas Introduction: History of Metal-Metal Dative Bonding Concept In 1961, Vaska and Diluzio synthesized a lemon-yellow compound known as the organometallic complex trans-[IrCl(CO)(PPh3)2]. This was achieved by reducing iridium(III) to iridium(I) using just triphenylphosphine and an alcohol. This was significant because they had prepared an iridium carbonyl complex without the use of carbon monoxide. This complex has reversible dioxygen coordination, but more importantly, it is extremely reactive with acids, halides, and dihydrogen yielding stable Ir(III) addition products. The discovery of this Iridium complex meant that laboratories across the globe could now easily create, in one step and several hours, an air-stable compound that could undergo oxidative addition reactions. Also, the reaction could be monitored by watching the carbonyl C-O stretching band in the IR spectrum and NMR spectroscopy later on. Because Vaska’s complex was so stable, its reactivity was limited. The complex serves as an excellent molecular platform for defining how oxidative addition reactions make homo- and heterogeneous catalysis a reality. While the term “oxidative addition is a staple in inorganic chemistry and catalysis, the step transition metal Lewis basicity is almost never seen. There are numerous methods that a metal can cleave an element-element bond, from concerted, side-on cleavage to backside attack. Most oxidative addition

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