New multidentate heteroscorpionate ligands: N-Phenyl-2,2-bis(pyrazol-1-yl)thioacetamide and ethyl 2,2-bis(pyrazol-1-yl)dithioacetate as well as their derivatives

Abstract

New multidentate heteroscorpionate ligands, N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,5-Me 2Pz) 2 ( 1), N-phenyl-2,2-bis(3,4,5-trimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,4,5-Me 3Pz) 2 ( 2), and ethyl 2,2-bis(3,5-dimethylpyrazol-1-yl)dithioacetate EtSCSCH(3,5-Me 2Pz) 2 ( 8), have been synthesized and their coordination chemistry studied. These heteroscorpionate ligands can act as monodentate, bidentate, or tridentate ligands, depending on the coordinate properties of different metals. Reaction of W(CO) 6 with 1 or 2 under UV irradiation yields monosubstituted carbonyl tungsten complexes W(CO) 5L (L = 1 or 2), in which N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide acts as a monodentate ligand by the s-coordination to the tungsten atom. In addition, these monosubstituted tungsten complexes have also been obtained by heating ligand 1 or 2 with W(CO) 5THF in THF. While similar reaction of Fe(CO) 5 with 1, 2, or 8 under UV irradiation results in tricarbonyl iron complexes PhHNCSCH(3,5-Me 2Pz) 2Fe(CO) 3 ( 5), PhHNCSCH(3,4,5-Me 3Pz) 2Fe(CO) 3 ( 6), and EtSCSCH(3,5-Me 2Pz) 2Fe(CO) 3 ( 9), respectively, in which N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide or ethyl 2,2-bis(pyrazol-1-yl)dithioacetate acts as a bidentate ligand through one pyrazolyl nitrogen atom and the C S π-bond in an η 2-C,S fashion side-on bonded to the iron atom to adopt a neutral bidentate κ 2-(π,N) coordination mode. Treatment of the lithium salt of 1 with Co(ClO 4) 2 · 6H 2O gives complex [PhNCSCH(3,5-Me 2Pz) 2] 2Co(ClO 4) with the oxidation of cobalt(II) to cobalt(III), in which N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide acts as a tridentate monoanionic κ 3-(N,N,S) chelating ligand by two pyrazolyl nitrogen atoms and the sulfur atom of the enolized thiolate anion.