Table 2.

Infrared spectral bands and assignments of STG and its complexes.

Assignments	Compounds
	STG	Mg(II)	Ca(II)	Cr(III)	Zn(II)	Cu(II)	Se(IV)
N–H stretching	3357	3300	3316	3340	3341	3305	3340
C–H stretching	3059 2917 2850	2918 2850	2917 2849	2919	2918 2850	2923 2854	2918 2851
C=O stretching	1669	-	-	-	-	-	-
C=N stretching	1634	1645	1634	1652	1635	1644	1646
NH2 bending	1609	-	-	-	-	-	-
C–C and C–N stretching	1556 1514 1426	1516	1518 1426	1515 1427	1579 1514 1424	1518 1426	1517 1426
CH in plane bending	1324 1274	1335 1311 1275	1336 1277	1315	1335 1274	1372 1335 1275	1315
C–F stretching	1146 978	1138 1015	1056	1159 1013	1107 1013	1140 1048	1107 1013
CH out-of-plane bending	913 881 844 725	889 848 665	891	950 897 664	894 667	845 621	951 897 664
M–O stretching	-	504	515	556	557	558 515	555 519
M–N stretching	-	446	476	445	477	466 445	440