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The cis isomer, whose full name is cis-diamminedichloroplatinum(II), was shown in 1969 by Barnett Rosenberg to have antitumor activity, and is now a chemotherapy drug known by the short name cisplatin. In contrast, the trans isomer (transplatin) has no useful anticancer activity.
See: cis–trans isomerism. cis (left) and trans (right) configured double bond in maleic acid and fumaric acid. cis (left) and trans (right) isomerism in a ring system. The descriptors cis (lat. on this side of) [2] and trans (lat. over, beyond) [3] are used in various contexts for the description of chemical configurations: [4] [5]
Traditionally, double bond stereochemistry was described as either cis (Latin, on this side) or trans (Latin, across), in reference to the relative position of substituents on either side of a double bond. A simple example of cis–trans isomerism is the 1,2-disubstituted ethenes, like the dichloroethene (C 2 H 2 Cl 2) isomers shown below. [7]
E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry.It is an extension of cis–trans isomer notation (which only describes relative stereochemistry) that can be used to describe double bonds having two, three or four substituents.
For ML a 4 L b 2, two isomers exist.These isomers of ML a 4 L b 2 are cis, if the L b ligands are mutually adjacent, and trans, if the L b groups are situated 180° to each other. It was the analysis of such complexes that led Alfred Werner to the 1913 Nobel Prize–winning postulation of octahedral complexes.
Simple cis and trans isomers may be indicated with a prefixed cis-or trans-: cis-but-2-ene, trans-but-2-ene. However, cis-and trans-are relative descriptors. It is IUPAC convention to describe all alkenes using absolute descriptors of Z-(same side) and E-(opposite) with the Cahn–Ingold–Prelog priority rules (see also E–Z notation).
And each of these cis-trans isomers can possibly have stable "chair" or "boat" conformations (although the barriers between these are significantly lower than those between different cis-trans isomers). The two isomeric complexes, cisplatin and transplatin, are examples of square planar MX 2 Y 2 molecules with M = Pt.
For monoalkenes, the configuration is often indicated by the prefixes cis- (from Latin "on this side of") or trans- ("across", "on the other side of") before the name, respectively; as in cis-2-pentene or trans-2-butene. The difference between cis-and trans-isomers. More generally, cis–trans isomerism will exist if each of the two carbons of ...