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The reaction most often occurs at an aliphatic sp 3 carbon center with an electronegative, stable leaving group attached to it, which is frequently a halogen (often denoted X). The formation of the C–Nu bond, due to attack by the nucleophile (denoted Nu), occurs together with the breakage of the C–X bond.
The proper name for this molecule is either trans-2-fluoro-3-methylpent-2-ene because the alkyl groups that form the backbone chain (i.e., methyl and ethyl) reside across the double bond from each other, or (Z)-2-fluoro-3-methylpent-2-ene because the highest-priority groups on each side of the double bond are on the same side of the double bond ...
An example of a torsion-free module that is not flat is the ideal (x, y) of the polynomial ring k[x, y] over a field k, interpreted as a module over k[x, y]. Any torsionless module over a domain is a torsion-free module, but the converse is not true, as Q is a torsion-free Z-module that is not torsionless.
In particular, if the stereocenters are configured in such a way that the molecule can take a conformation having a plane of symmetry or an inversion point, then the molecule is achiral and is known as a meso compound. Molecules with chirality arising from one or more stereocenters are classified as possessing central chirality.
Zero field splitting (ZFS) describes various interactions of the energy levels of a molecule or ion resulting from the presence of more than one unpaired electron. In quantum mechanics , an energy level is called degenerate if it corresponds to two or more different measurable states of a quantum system.
The D- and L- prefixes describe the molecule as a whole, as do the (+) and (−) prefixes for optical rotation. In contrast, the ( R )- and ( S )- prefixes from the Cahn–Ingold–Prelog priority rules characterize the absolute configuration of each specific chiral stereocenter with the molecule, rather than a property of the molecule as a whole.
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 .
The complexification of the Lie algebra () is (;), the space of all n × n complex matrices with trace zero. [15] A Cartan subalgebra then consists of the diagonal matrices with trace zero, [ 16 ] which we identify with vectors in C n {\displaystyle \mathbb {C} ^{n}} whose entries sum to zero.