Table 2. Number of structures and fragments containing carboxyl(ate) groups in the CSD.

Only low R-factor structures (R 0.05) are considered. Statistics were also collected for the anti conformer subgroups that take into account the carboxyl groups that are involved in intra- and intermolecular hydrogen bonds, respectively. Distances are in , angles in .

	No. of structures	No. of fragments	d(CO)	d(CO)	(OCO)	(CCO)	(CCO)	(CCOH)
Carboxyl-syn	6852	9295	1.22 0.02	1.31 0.02	124 1	123 2	113 2	111 3
Carboxyl-anti (intermolecular)	209	223	1.21 0.01	1.31 0.02	121 2	122 2	117 2	112 4
Carboxyl-anti (intramolecular)	760	945	1.22 0.01	1.30 0.02	121 1	120 2	118 2	110 4
Carboxylate	5353	6760	1.25 0.02		125 2	117 2