Synthesis and Characterization of Coordination Compounds of Chelating Ligands Containing Imidazole Groups. The Crystal and Molecular Structures of the Dinuclear CuI and CuII Compounds dicopper(I)Bis(perchlorate) and ...

Article abstract of DOI:10.1021/ja00377a012

Copper(I) and copper(II) coordination compounds with general formulas Cu^II(L)(anion)2, Cu^II2(L)(anion)4, and Cu^I(L)(anion)2 have been prepared and characterized, where L stands for one of the sexadentate benzimidazole-containing ligands N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-1,2-ethanediamine (abbreviated EDTB), N,N,N',N'-tetrakis<(1-methyl-2-benzimidazolyl)methyl>-1,2-ethanediamine (NMEDTB), N,N,N',N'-tetrakis<(1-benzyl-2-benzimidazolyl)-methyl>-1,1-ethanediamine (NBEDTB), N,N,N',N'-tetrakis<(5-methyl-2-benzimidazolyl)methyl>-1,2-ethanediamine (5-MEDTB),or N,N,N',N'- tetrakis<(5,6-dimethyl-2-benzimidazolyl)methyl>-1,2-ethanediamine (5,6-DMEDTB).The electronic and ECR spectra of all compounds of the composition Cu^II(L)(anion)2 are identical with those for Cu(EDTB)(anion)2 and suggest a structure similar to the one found for Cu(EDTB)(BF4)(BF3OC2H5), which has been described as highly distored square pyramid.ECR and electronic spectra of the compounds Cu2(L)(anion)2 indicate different coordination geometries in the presence of different anions.In compounds with Cl^- or Br^- the Cu^II atom appears to have trigonal-bipyramidal coordination geometry.Square-pyramidal geometry seems more likely for compounds Cu2(L)X4, where X=NO3^-, BF4^-, or ClO4^-.The crystal and molecular structures of II2(NMEDTB)(NO3)3>NO3*4H2O (1) and of Cu^I2(EDTB)(ClO4)2 (2) have been determined by single-crystal X-ray analysis.Both compounds crystallize in space group C2/c.For compound 1, a=19.159 (4) Angstroem b=15.907(2) Angstroem, c=16.816(3) Angstroem, β=109.57(2)deg, V=4829.0 Angstroem ³, Z=4, d_measd=1.51(1) g cm^-3, and d_calcd=1.49 g cm^-3.The intensities of 4241 independent reflections were measured on an automatic diffractometer, 2670 of which were considered as observed (I>2?(I)).For compound 2, a=13.849 (2) Angstrom, b=18.913(2) Angstroem, c=14.062(2) Angstroem, β=102.10(1) deg, V=3592.2 Angstroem ³, Z=4, d_measd=1.65(1) g cm^-3, and d_calcd=1.68 g cm^-3.A total of 3522 independent reflections were measured, 2627 of which were considered as observed.Both structures were solved by heavy-atom methods and refined by using least-squares techniques to a residual R value of 0.046 for 1 and 0.039 for 2.Structure 1 consists dinuclear Cu2(NMEDTB)(NO3)3⁺ cations having C2 symmetry, a disordered nitrate ion, and disordered water molecules.The coordination geometry around each copper ion can be described as square pyramidal with two equatorial benzimidazole nitrogen atoms, one equatorial amine nitrogen atom, one equatorial oxygen atom of monodentante coordinating nitrate ion, and one axial oxygen atom of a nitrate ion which is bridging to the axial position of the copper ion in the cation.Structure 2 consists of dinuclear Cu^I2(EDTB)²⁺ cations having C2 symmetry and perchlorate ions.Each copper is linearly coordinated by two benzimidazole nitrogen atoms, with short Cu-N bonds of 1.869(4) and 1.876(4) Angstroem, respectively.The Cu-Cu ...