Tautomeric Conversion of a Thiourea Ligand upon Formation of a Hypervalent Tellurium (II) Complex. Synthesis, and X-ray Structural Studies of N-Phenyl-N’-(1,3-Thiazol-2-YL)-Thiourea and Bromophenyl [1-Phenyl-3-(1’,3’-Thiazol-3’-ium-2’-YL)-isothioureidato]tellurium
Taylor & Francis
Phosphorus, Sulfur, and Silicon and the Related Elements
The divalent tellurium title complex (II) has been synthesized by addition of Ph2Te2 and Br2 to the ligand 1-phenyl-3-(2-thiazolyl)-2-thiourea (I).The molecular structures of I and II were subsequently determined by X-ray crystallographic methods. As a result, it was found that upon complexation, the ligand had undergone a transition from a thiourea to to an isomeric isothiourea, involving a transfer of a thiourea proton to the thiazolyl ring. This does not seem to influence the bonding properties of the ligand, and the reasons for this are discussed. The central tellurium atom is three-coordinate and its coordination sphere is T-shaped with a linear S-Te-Br sequence with bond lengths Te(1)-S(1) and Te(1)-Br(1) equal to 2.548(1) and 2.883(1) Å, respectively, and ∠ S(1)-Te(1)-Br(1)=174.49(2)°. At nearly right angles to this sequence, there is a Te(1)-C(11)(phenyl) bond of 2.127(3) Å.