Reductive electrocrystallization at a constant current density (1 1 .0-11.5 pA/cm2) of millimolar solutions of [ M (~~Y ) , ] ( P F~)~, where M = Fe, Ru, or Os, and bpy = 2,T-bipyridine in acetonitrile containing 0 . 1~ Bu4NPF, results in the formation of dark crystals on the Pt cathode. The crystals grow as long, thin, and shiny needles having a hexagonal cross section of 0.14.5 mm in diameter.
1.Introduction. -A recent article began by stating that 'tris(2,2'-bipyridine)ruthenium(II), Ru(bpy)?, has evolved from a quite esoteric complex ion of a rare platinum metal into an immensely popular, almost magic compound' [l]. We present here evidence of new crystalline materials derived from this molecule and the related species [Fe(bpy),12+ and [Os(bpy)J2+ which gives further support for this statement. Despite the multiple electrochemical [2] and photochemical [3] studies that have been performed with [Ru(bpy),]'+ for over two decades, there was no indication that these novel crystalline materials had been previously communicated.Part of the impetus behind the present work stemmed from our recent success in preparing the first crystalline CRYPTATIUM in 1991 ; a neutral, expanded-atom type species, structure 1, formed by the reductive electrocrystallization of sodium tris(2,2'-bipyridy1)cryptate [4a]. The overall interest in the electrochemical properties of similar macrobicycles, macrocycles, and even of carbon clusters was directed by the possibility of manipulating and transforming them into novel materials with unique properties [4b].The reduced complex 1 can be represented as [Na' c (bipy),], where (bipy), stands for the tris(2,2'-bipyridyl) cryptand, not for three isolated bpy groups. The X-ray structure of this CRYPTATIUM was solved and indicated that the extra unpaired electron that was added to the system upon electrocrystallization was localized in one of the three bipy units of the cryptand [4a].
