Cation–π interactionCation–π interaction is a noncovalent molecular interaction between the face of an electron-rich π system (e.g. benzene, ethylene, acetylene) and an adjacent cation (e.g. Li+, Na+). This interaction is an example of noncovalent bonding between a monopole (cation) and a quadrupole (π system). Bonding energies are significant, with solution-phase values falling within the same order of magnitude as hydrogen bonds and salt bridges.
Spectrochemical seriesA spectrochemical series is a list of ligands ordered by ligand "strength", and a list of metal ions based on oxidation number, group and element. For a metal ion, the ligands modify the difference in energy Δ between the d orbitals, called the ligand-field splitting parameter in ligand field theory, or the crystal-field splitting parameter in crystal field theory. The splitting parameter is reflected in the ion's electronic and magnetic properties such as its spin state, and optical properties such as its color and absorption spectrum.
Direct-attached storageDirect-attached storage (DAS) is digital storage directly attached to the computer accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage). DAS consists of one or more storage units such as hard drives, solid-state drives, optical disc drives within an external enclosure. The term "DAS" is a retronym to contrast with storage area network (SAN) and network-attached storage (NAS).
Crown etherIn organic chemistry, crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups (). The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., . Important members of this series are the tetramer (n = 4), the pentamer (n = 5), and the hexamer (n = 6). The term "crown" refers to the resemblance between the structure of a crown ether bound to a cation, and a crown sitting on a person's head.
PermanganateA permanganate (p@r'maeNg@neit,_p3r-) is a chemical compound with the manganate(VII) ion, MnO4−, the conjugate base of permanganic acid. Because the manganese atom has a +7 oxidation state, the permanganate(VII) ion is a strong oxidising agent. The ion is a transition metal ion with a tetrahedral structure. Permanganate solutions are purple in colour and are stable in neutral or slightly alkaline media. The exact chemical reaction depends on the carbon-containing reactants present and the oxidant used.
Methylcyclopentadienyl manganese tricarbonylMethylcyclopentadienyl manganese tricarbonyl (MMT or MCMT) is an organomanganese compound with the formula (C5H4CH3)Mn(CO)3. Initially marketed as a supplement for use in leaded gasoline, MMT was later used in unleaded gasoline to increase the octane rating. Following the implementation of the Clean Air Act (United States) (CAA) in 1970, MMT continued to be used alongside tetraethyl lead (TEL) in the US as leaded gasoline was phased out (prior to TEL finally being banned from US gasoline in 1995), and was also used in unleaded gasoline until 1977.
Monatomic gasIn physics and chemistry, "monatomic" is a combination of the words "mono" and "atomic", and means "single atom". It is usually applied to gases: a monatomic gas is a gas in which atoms are not bound to each other. Examples at standard conditions of temperature and pressure include all the noble gases (helium, neon, argon, krypton, xenon, and radon), though all chemical elements will be monatomic in the gas phase at sufficiently high temperature (or very low pressure).
