An essential guide and reference to CIF for programmers, data managers handling crystal-structure information and practising crystallographers.
Formula with each discrete bonded residue or ion shown as a separate moiety. See the _chemical_formula_ category description for rules for writing chemical formulae. In addition to the general formulae requirements, the following rules apply: (1) Moieties are separated by commas ','. (2) The order of elements within a moiety follows general rule (5) in the _chemical_formula_ category description. (3) Parentheses are not used within moieties but may surround a moiety. Parentheses may not be nested. (4) Charges should be placed at the end of the moiety. The charge '+' or '-' may be preceded by a numerical multiplier and should be separated from the last (element symbol + count) by a space. Pre- or post-multipliers may be used for individual moieties.Examples:
|'C7 H4 Cl Hg N O3 S'|
|'C12 H17 N4 O S 1+, C6 H2 N3 O7 1-'|
|'C12 H16 N2 O6, 5(H2 O1)'|
|'(Cd 2+)3, (C6 N6 Cr 3-)2, 2(H2 O)'|