Nickel(II) DBM, Brown Form. A sample of the light-green form
of the complex was placed under a layer of dried warm (70 °C) solvent
(xylenes, toluene, or chlorobenzene) for 30 min or until the light-green
powder completely transformed to brown prismatic crystals. These were
separated from the warm supernatant fluid (drybox), rinsed with solvent,
and dried. Anal. Found: C, 71.3; H, 4.35. Calcd for [Ni(DBM)2]
(C30H22NiO4): C, 71.3; H, 4.39. A single crystal for X-ray study was
obtained from chlorobenzene.