Syntheses, structural determination, and binding studies of binuclear nine-coordinate (MnH)4[Ho2III(Dtpa)2] · 12H2O and polynuclear nine-coordinate {(MnH)[HoIII(Egta)] · 3H2O}n

Abstract

Two novel rare earth metal coordination compounds, (MnH)₄[Ho₂^III(Dtpa)₂] · 12H₂O (I) (Mn = methylamine, H₅Dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaaceticacid) and {(MnH)[Ho^III(Egta)] · 3H₂O}_n (II) (H₄Egta = ethyleneglycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) have been successfully synthesized through direct heating reflux and characterized by FT-IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction techniques (CIF files CCDC nos. 890878 (I) and 1457061 (II)). Complex I shapes a binuclear nine-coordinate structure with distorted tricapped trigonal prismatic conformation and crystallizes in the triclinic crystal system with space group P1̄. The central Ho³⁺ ion is coordinated by three nitrogens and six oxygens from two octadentate Dtpa ligands. The cell dimensions are as follows: a = 9.8420(10), b = 12.1319(13), c = 13.2931(15) Å, α = 89.223(2)°, β = 68.4280(10)°, γ = 72.1280(10)° and V = 1396.0(3) ų. Complex II adopts a polynuclear nine-coordinate structure with pseudo-monocapped square antiprismatic conformation and crystallizes in the monoclinic crystal system with space group C2/c. The central Ho³⁺ ion is coordinated by two nitrogens and seven oxygens from two octadentate Egta ligands. The crystal data are as follows: a = 38.4755(13), b =13.5569(5), c = 8.7343(3) Å, β = 100.135(3)° and V = 4484.8(3) ų.