Chemical element or an electrophile; similarly "Nu" denotes a nucleophile. "L" is used to represent a general ligand in inorganic and organometallic chemistry. "M" is also often used in place of a general metal. At least two additional, two-letter generic chemical symbols are also in informal usage, "Ln" for any lanthanide element and "An" for any actinide element. "Rg" was formerly used for any rare gas element, but the group of rare gases has now been renamed noble gases and the symbol "Rg" has now been assigned to the element roentgenium. Isotopes are distinguished by the atomic mass number (total protons and
Cobalt-59 nuclear magnetic resonance Cobalt-59 nuclear magnetic resonance Cobalt-59 nuclear magnetic resonance is a form of nuclear magnetic resonance spectroscopy that uses cobalt-59, a cobalt isotope. Co is a nucleus of spin 7/2 and 100% abundancy. The nucleus has a magnetic quadrupole moment. Among all NMR active nuclei, Co has the largest chemical shift range and the chemical shift can be correlated with the spectrochemical series. Resonances are observed over a range of 20000 ppm, the width of the signals being up to 20 kHz. A widely used standard is potassium hexacyanocobaltate (0.1M KCo(CN) in DO), which, due to its high symmetry, has a