- Isolobal principle
The isolobal principle in
organometallic chemistry devised byRoald Hoffmann aims to improve the understanding ofchemical bonding in molecules by identifying molecules that share a commonfrontier orbital type, approximate energy and occupancy just asisoelectronic molecules share the same number ofvalence electron s and structure Ref|Hoffmann. When representing pairs of isolobal structures, they are connected through a two-pointed array with half an arrow below.The
methyl radical is isolobal with themetal carbonyl species manganese pentacarbonyl Mn(CO)5 because both molecules have a single electron in a hybrid orbital pointing away from the plane of the molecule (though they are not isoelectronic). This resemblance is reflected in the chemistry of both molecules. As the methyl radical can dimerize toethane , Mn(CO)5 can dimerize to (CO)5Mn-Mn(CO)5 and both radicals can even form Mn(CO)5CH3.In the same way iron tetracarbonyl Fe(CO)4 is isolobal with the
carbene CH2 because they both have two electrons contained in two hybrid orbitals. methylene dimerizes to ethylene and both fragments can couple to a carbene complex.External links
* [http://nobelprize.org/chemistry/laureates/1981/hoffman-lecture.pdf Nobel Prize in Chemistry 1981 lecture]
* More isolobal structures: [http://www.wellesley.edu/Chemistry/chem241/isolobal.html link]
* Even more isolobal structures [http://www.chem.uh.edu/Courses/Albright/Chem6312/ch15/chpt15.html Link]References
# "Building Bridges Between Inorganic and Organic Chemistry (Nobel Lecture)" Roald Hoffmann
Angewandte Chemie International Edition Volume 21, Issue 10, Date: October 1982, Pages: 711-724
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