Dinuclear transition metal compounds of a decadentate pyrazole-containing chelating ligand. X-ray crystal structure of Co 2(tthd)(ClO 4) 4(H 2O) 2(MeOH) 1.75

Abstract

A potentially decadentate ligand, 1,1,4,7,10,10-hexakis(3,5-dimethyl-1-pyrazolylmethyl)-1,4,7,10-tetraazadecane (tthd), has been synthesized from the reaction of tri-ethylenetetramine with six equivalents of N-hydroxymethyl-3,5-dimethylpyrazole. The tthd ligand forms coordination compounds, M 2(tthd)(ClO 4) 4(H 2O) x , when M is Co, Ni, Cu, Zn and Cd and x = 4–8; and M 2(tthd)(A) 2(ClO 4) 2(H 2O) x when M is Co and Ni, A is NCS or Cl, and x = 4–8. The cobalt compound, Co 2(tthd)(ClO 4) 2(H 2O) 2(MeOH) 1.75, crystallizes in the triclinic space group P1, a = 1.959(2), b = 1.5657(3), c = 2.1244(3) nm, α = 105.5(1), β = 96.9(1), γ = 112.1(1). Due to severe disorder of the anions the structure could only be refined to an R w, value of 0.099. The ligand acts as a decadentate, dinucleating ligand. The cobalt ions are distorted octahedrally surrounded by five N-atoms of the tthd ligand and an O-atom of water occupying the sixth coordination place. The other perchlorate compounds have very similar structures, as can be concluded from spectroscopic data. In the thiocyanate and chloride compounds the anions have replaced the coordinated water molecules, resulting in octahedral Ni compounds. With Co thiocyanate, however, tthd acts as an octadentate ligand, resulting only in five-coordinated compounds.