X-Ray Crystal Structures of cis- and trans-Dinitrobis(1,4-butanediamine)cobalt(III) Nitrates. Conformation of Seven-Membered Chelate Rings

Abstract

Abstract The structures of cis- and trans-dinitrobis(1,4-butanediamine)cobalt(III) nitrates were determined by the single-crystal X-ray diffraction method. cis-[Co(NO2)2(tmd)2]NO3 (tmd=H2N(CH2)4NH2) is monoclinic with the space group P21⁄a; the cell constants are a=23.878(4), b=8.403(1), c=16.675(3) Å, β=103.24(1)°; Z=8, and the final R value was 0.051. trans-[Co(NO2)2(tmd)2]NO3·H2O is triclinic with the space group P\bar1; the cell constants are a=9.753(3), b=13.909(4), c=6.327(1) Å, α=102.07(2), β=91.05(2), γ=87.83(3)°; Z=2, and the final R value was 0.058. Both complexes have a slightly distorted octahedral geometry around the cobalt center. The conformations of the seven-membered chelate rings have twist-chair and chair forms for the cis and trans complexes, respectively.