Different complexation behaviour of a proton transfer compound obtained from pyridine-2,6-dicarboxylic acid and creatine with Tl(I), Cu(II), Fe(III), and Bi(III): synthesis, characterization, crystal structures and solution studies

The dif fer ent complexation meth ods of a pro ton trans fer com pound, (creatH)(pydcH)·H2O (pydcH2 = pyridine-2,6-di car box yl ic acid; creat = creatinine) with metal ions have been stud ied and for ma tion of [(Tl(pydcH)]n (1) , [(Fe(pydc)(H2O)2)2ox]·6H2O (2), [Cu(pydc)(pydcH2)]·2H2O (3) and (creatH)2[Bi(pydc)2]2·4H2O (4) are re ported. The char ac ter iza tion was per formed us ing IR spec tros copy and sin gle crys tal X-ray dif frac tion anal y sis. The Tl(I) com plex [(Tl(pydcH)]n (1) ob tained from (creatH)(pydcH)·H2O is a poly meric sys tem, show ing only the con tri bu tion of the an ionic spe cies of (creatH)(pydcH)·H2O to the complexation. The Fe(III) and the Cu(II) com plexes [(Fe(pydc)(H2O)2)2ox]·6H2O (2) (ox = ox a late) and [Cu(pydc)(pydcH2)]·2H2O (3) were also ob tained from (creatH)(pydcH)·H2O. The Bi(III) com plex (creatH)2[Bi(pydc)2]2·4H2O (4) is a dimeric sys tem, show ing both con tri bu tion of the cationic and an ionic frag ments. The com plexes 1–4 show a va ri ety of struc tural fea tures in clud ing mononuclear, binuclear, poly meric struc tures and un usual ligand for ma tion. In com pounds (1), (2), (3) and (4), a large num - ber of hy dro gen bonds are ob served. These in ter ac tions as well as p-p stack ing play an im por tant role in the for ma tion and sta bi li za tion of supra mo lecu lar sys tems in the crys tal lat tices. The stoichiometry and sta bil ity of the Cu(II), Tl(I) and Bi(III) com plexes with (pydc)(creat) and Fe(III) with pydc-ox mix ture in aque ous so lu tion were in ves ti gated by potentiometric pH ti tra tion.