Crystal structures and magnetic studies of six new nickel(II) amine mu-oxalato compounds

Six new nickel(II) binuclear oxalato-bridging compounds were obtained and c rystal structures were solved at room temperature. Factors influencing the nitrite coordination modes are discussed. [mer-Ni-2(3,3'-diamino-N-methyldi propylamine)(2)(OH2)(2)(mu-OX)]Cl-2. 3H(2)O (I), Ni2C16Cl2H48N6O9 is a mu-o xalato bridged dimer with a Medpt ligands in the mer conformation, a nitro( N) ligand trans to the N-methyl group and a water ligand trans to an oxalat o oxygen. Green [fac-Ni-2(3,3'-diamino-N-methyldipropylamine)(2)(ONO)(2)(mu -OX)] (II), Ni2C16H38N8O8 is also a mu-oxalato bridged dimer with a fac-Med pt, making this substance unique since it is the only fac-dpt compound ever made. The nitro(O) ligand is trans to the N-methyl group. Violet [mer-Ni-2 (3,3'-diamino-N-methyldipropylamine)(2)(NO2)(2)(mu-OX)]. 2H(2)O (III), Ni2C 16H42N8O10 is interesting as this compound came from the same reaction pot as II. The two are readily separated by hand since their colors differ dras tically. It is also a mu-oxalato bridged dimer with mer-Medpt but the nitro ligand is (O) bound and trans to an oxalato oxygen. [mer-Ni-2(N-(3-aminopr opyl)-1,3-propanediamine)(2)(OH2)(2)(mu-OX)]Cl-2 (IV), Ni2C14Cl2H38N6O6 is also a mu-oxalato bridged dimer with an unmethylated dpt ligand in mer conf ormation. The sixth position of the coordination sphere is a water located trans to an oxalato oxygen. [mer-Ni-2(N-(3-aminopropyl)-1,3-propanediamine) (2)(OH2)(2)(mu-OX)]Cl(NO2) (V), Ni2C14ClH38N7O8. The amine ligand of both n ickels are mer, an oxalato bridge links the two metal centers and a water o ccupies a site trans to an oxalato oxygen. It is surprising to find a nitro ligand as a counter ion while a water occupies a coordination site. Normal ly, one would expect displacement of the aquo ligand by NO2-. [mer-Ni-2(N-( 2-aminoethyl)-1,3-propanediamine)(2)(OH2)(2)(mu-OX)](ClO4)(2) (VI), Ni2C12C l2H34N6O14. The mer-aep and the mu-oxalato ligands fill five positions of t he coordination sphere of this dimer. The other positions are taken up by w ater molecules located trans to an oxalato oxygen. The structures of all si x compounds were determined and the temperature dependence of their magneti c susceptibility were also established. (C) 1999 Elsevier Science S.A. All rights reserved.