Synthesis and characterization of copper (I) and copper (II) complexes with 1,5-bis (benzimidazol-2-yl)-3-thiapentane

Abstract

Complexes with formula <span style="font-size: 14.0pt;font-family:HiddenHorzOCR;mso-bidi-font-family:HiddenHorzOCR">[Cu(BBES)X₂]_.nH₂O have been synthesized where BBES is a tridentate ligand containing bis-benzimidazolyl as pendant coordinating group and X is an exogenous anionic ligand (X = HCOO^- , CH₃COO^- ,Cl^-, Br^-, NO^-₃). Solution EPR spectroscopy on these complexes reveals that the ground state in these copper (II) complexes comprises <i style="mso-bidi-font-style:normal">^d </i>_x2-y2orbital. Cyclic voltammetric studies reveal that <i>E</i>_{<span style="font-size:14.0pt;font-family:Arial;mso-bidi-font-style:italic">1/2</span>}for Cu(II)/Cu(I) couple shifts cathodically with HCOO^- as the anionic ligand, implying that

binding of this anion stabilizes the Cu (II) state whereas <i>E</i>_{<span style="font-size:14.0pt; font-family:Arial;mso-bidi-font-style:italic">1/2</span>} , data for NCS^-indicates that this anion destabilizes Cu(II) state. Copper

<span style="font-size:14.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">(I) complex has also been synthesised in the presence of hydroquinone which shows a well-resolved NMR spectrum in the range <span style="font-size:14.0pt;font-family:Arial;mso-fareast-font-family:" times="" new="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">0-10 <span style="font-size:14.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">ppm.</span></span></span></span>