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

Two novel rare earth metal coordination compounds, (MnH) 4 [Ho 2 III (Dtpa) 2 ] · 12H 2 O ( I ) (Mn = methylamine, H 5 Dtpa = diethylenetriamine- N , N , N ′, N ″, N ″-pentaaceticacid) and {(MnH)[Ho III (Egta)] · 3H 2 O} n ( II ) (H 4 Egta = 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 P 1̄. The central Ho 3+ 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) Å 3 . Complex II adopts a polynuclear nine-coordinate structure with pseudo-monocapped square antiprismatic conformation and crystallizes in the monoclinic crystal system with space group C 2/ c . The central Ho 3+ 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) Å 3 .