Thiazole Complexes with Metal Atoms

All the early literature concerning thiazoles mentions numerous metallic complex-salts formed by addition to the thiazole of the aqueous solution of the metal salt and that could be used for identification purposes. The most usual complexes so obtained are platinum double salts, for example, (4-methylthiazole HC1)2 PtCU (m.p. deep 204°C) (25), or mercuric chloride derivatives, for example, 2,4-dimethyl-thiazole 2 HgCl (m.p. deep 176-177°C) (458). 

Erlenmeyer and Schmid (459), in the course of a fundamental comparison between pyridine and its isosteric thiazole structures, prepared the 

The first identified complexes of unsubstituted thiazole were described by Erlenmeyer and Schmid (461) they were obtained by dissolution in absolute alcohol of both thiazole and an anhydrous cobalt(II) salt (Table 1-62). Heating the a-CoCri 2Th complex in chloroform gives the 0 isomer, which on standirtg at room temperature reverses back to the a form. According to Hant2sch (462), these isomers correspond to a cis-trans isomerism. Several complexes of 2,2 -(183) and 4,4 -dithiazolyl (184) were also prepared and found similar to pyridyl analogs (185) (Table 1-63). Zn(II), Fe(II), Co(II), Ni(II) and Cu(II) chelates of 2.4-/ is(2-pyridyl)thiazole (186) and (2-pyridylamino)-4-(2-pyridy])thiazole (187) have been investigated. The formation constants for species MLr, and ML - (L = 186 or 187) have been calculated from data obtained by potentiometric, spectrophotometric, and partition techniques. 

TABLE 1-62. COMPLEXES OF THIAZOLE (Th) AND PYRIDINE (Py) WITH Co(H) SALTS (461) 

Thiazole complex Color Pyridine complex Color 

---

Since 1983 a large number of structures of thiazole derivatives have been determined by x-ray analysis. The structures of complexes with metal atoms were also obtained mixed copper(I) complexes with l,3-thiazolidine-2-thione and triarylphosphines have been found to be dimeric with the thione ligand bridging two metal atoms <9iiCA(i84)16l, 9IPOL935>. Monomeric complexes between... 

Raubenheimer et al. have developed a third route for transition metal NHC complexes with thiazol-2-ylidene, benzothiazol-2-yUdene and even isothiazol-5-ylidene ligands [45 9]. This method uses a thiazolyl transfer from lithium to a transition metal with subsequent protonation [47,49-54] or alkylation [41,45,46,48,51-56] of the nitrogen atom to generate the transition metal NHC complex. In this way, carbene complexes of copper(I)... 

The structure of (9-methyladenine)ZnCl2 is polymeric each zinc ion is tetrahedrally co-ordinated to two chlorine atoms (Zn—Cl = 2.22 AX and to N(l) and N(7) of neighbouring adenine moieties (Zn—N = 2.05 A).Complexes of the stoicheiometry [ML3][C104]2[L = thiabendazole (1)] contain the metal in an octahedral co-ordination with the chelating ligand co-ordinated via the nitrogens of the imidazole and thiazole rings. 

Thiamine is a monovalent cation with a structure that corresponds to a substituted pyrimidine bonded to a substituted thiazole. This structure leads to the presence of a quaternary N atom attached to the thiazole ring. Thus, thiamine - so-called vitamin Bl - exists as salts of the physiological chloride anion or one of a wide variety of other counter anions. For solubility reasons, thiamine is commercially available as its hydrochloride salt, namely thiaminium(2+) dichloride. The structures of thiamine metal complexes correspond to two groups those containing the divalent thiaminium cation and a cadmium complex as counterion, and those in which there is a direct cadmium-thiamine interaction. 

---