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The '''mesomeric effect''' or '''resonance effect''' in [[chemistry]] is a property of [[substituent]]s or [[functional group]]s in a [[chemical compound]]. The effect is used in a qualitative way and describes the electron withdrawing or releasing properties of substituents based on relevant [[resonance structure]]s and is symbolized by the letter '''M'''. The mesomeric effect is negative ('''-M''') when the substituent is an electron-withdrawing group and the effect is positive ('''+M''') when based on resonance the substituent is an electron releasing group.
'''''Rosencrantz & Guildenstern Are Dead''''' is a [[comedy|humorous]], [[Theatre of the Absurd|absurdist]], [[tragedy|tragic]] and [[existentialism|existentialist]] [[play]] by [[Tom Stoppard]], first staged in [[1966]].
*Examples of -M substituents: [[acetyl]] (UPAC ethanoyl) - [[nitrile]] - [[nitro]]
The play is structured as the inverse of [[William Shakespeare|Shakespeare's]] ''[[Hamlet]]''. Two minor characters in the original, [[Rosencrantz]] and [[Guildenstern]], are the leads in this play; they are on-stage here when they are off-stage in Shakespeare's play, with the exception of a few short scenes taken directly from the original.
*Examples of +M substituents: [[alcohol]] - [[amine]]
The net electron flow from or to the substituent is determined also by the [[inductive effect]]. It's important to note that the mesomeric effect as a result of p - orbital overlap (resonance) has absolutely no effect on this inductive effect, as the inductive effect is purely to do with the [[electronegativity]] of the atoms and their structural chemistry (which atoms are connected to which).
The two characters and those they encounter often confuse their names, as they are not certain of their own identities. They are portrayed as two clowns or fools in a world that is beyond their understanding; they cannot identify any reliable feature or the significance in words or events. Their own memories are not reliable or complete and they misunderstand each other as they stumble through philosophical arguments while not realizing the implications to themselves.
The concepts of mesomeric effect, '''mesomerism''' and '''mesomer''' were introduced by [[Christopher Kelk Ingold|Ingold]] in 1938 as an alternative to the [[Linus Pauling|Pauling's]] synonymous concept of [[resonance effect|resonance]] <ref>''If It's Resonance, What Is Resonating?'' Kerber, Robert C. . J. Chem. Educ. '''2006''' 83 223. [http://www.jce.divched.org/Journal/Issues/2006/Feb/abs223.html Abstract]</ref>. Mesomerism is in this context is often encountered in German and French literature but in English literature the term resonance dominates.
Several important themes in the play:
* [[Existentialism]] - why are we here? Why should Rosencrantz and Guildenstern do anything unless someone asks them to? They find themselves as pawns in a gigantic game of [[chess]], yet make no effort whatsoever to escape.
* [[Free will]] vs. [[determinism]] - is it their choice to perform actions, or are they fated to live the way they do? The implication the play gives is that it doesn't matter what choices Rosencrantz and Guildenstern make, their fate has been sealed. ''Hamlet'' ends with the news of their deaths, so they have to die.
* Search for value - what is important? What is not? Does anything matter? If we are all going to die, why do we continue to live?
== External links==
These themes, and the presence of two central characters who almost appear to be two halves of a single character, are shared with [[Samuel Beckett]]'s ''[[Waiting for Godot]]'', and the two plays are often compared.
* IUPAC [[Gold Book]] [http://www.iupac.org/goldbook/M03844.pdf definition]
== See also ==
The play was filmed in 1990, directed by Stoppard, starring [[Gary Oldman]] and [[Tim Roth]] in the leading roles, [[Richard Dreyfuss]] as the player, [[Joanna Roth]] as [[Ophelia (character)|Ophelia]] and [[Iain Glen]] as Hamlet.
* [[List of publications in chemistry#Organic chemistry|Important publications in organic chemistry]]
== External linksReferences ==
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[[Category: PlaysChemical bonding]] ▼* [http://www.imdb.com/title/tt0100519/ IMDB entry of the film adaptation]
* [http://www.mala.bc.ca/~johnstoi/introser/stoppard.htm Lecture] (public ___domain) by Ian Johnston of Malaspina University-College
[[de:Mesomerer Effekt]]
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