CHEMM01

PROC-NAME: CHEMM01 Type_1

PURPOSE: To check that the moiety formula follows the CIF-dictionary definition.

PROCEDURE:

Read the formula according to the CIF rules and xcheck against the sum formula.

IF _chemical_formula_moiety contains an invalid character then issue ALERT B
   "Alert B The moiety formula contains an invalid character."
IF _chemical_formula_moiety contains an invalid element symbol then issue ALERT A
   "Alert A The moiety formula contains an invalid element symbol."
IF _chemical_formula_moiety contains elements in the wrong order then issue ALERT B
   "Alert B The moiety formula contains elements in the wrong order."

_chemical_formula_moiety has the identical format to _chemical_formula_sum, namely C, H, then alphabetical, with the exception that the individual unconnected independent entities in the structure are listed separately. A common mistake is to attempt to depict organometallic coordination with this entry. Such coordination can be given under _chemical_formula_structural or _chemical_formula_IUPAC if desired, but must never be given as _chemical_formula_moiety. Furthermore, do not use subscript formatting: C10 H20 is correct, C~10~ H~20~ is not. Nesting of parentheses is also not allowed.

Correct examples:
_chemical_formula_moiety    'C7 H4 Cl Hg N O3 S'
_chemical_formula_moiety    'C12 H17 N4 O S 1+, C6 H2 N3 O7 1-'
_chemical_formula_moiety    'C12 H16 N2 O6, 5(H2 O1)'
_chemical_formula_moiety    '(Cd 2+)3, (C6 N6 Cr 3-)2, 2(H2 O)'

Formulae like '[Co Re (C12 H22 P)2 (C O)6].0.5C H3 O H' and
'(Pt (N H3)2 (C5 H7 N3 O)2) (Cl O4)2' are INCORRECT for _chemical_formula_moiety.
However these can be given as:
_chemical_formula_IUPAC '[Co Re (C12 H22 P)2 (C O)6].0.5C H3 O H'
_chemical_formula_structural '(Pt (N H3)2 (C5 H7 N3 O)2) (Cl O4)2'

Full list of validation algorithms