Different reaction temperatures have allowed the isolation of 1 : 1 and 1 : 2 adducts of phthalocyaninatocobaIt(i1) with pyridine and 4-methylpyridine. Thermal, vibrational, and magnetic-susceptibility analyses have provided useful information about the structural properties of these complexes ; e.s.r. and electronic spectra have permitted a detailed investigation of the ligand-field levels of the cobalt atom. All the adducts react with oxygen and form, at low temperatures, well characterized Co : O2 1 : 1 adducts.THE large number of papers on the properties and chemical reactivity of phthalocyanine complexes published in the last few years 1-4 emphasizes the continual interest shown in these compounds. Their structural similarity with the heme proteins suggests that transition-metal phthalocyanines can be used as model compounds for natural products; 2*5 in addition, the catalytic activity 6 9 7 shown in oxygen reduction or in oxidative dehydrogenation suggests that investigation of the catalysis mechanism can be further extended. The ability of [Co(pc)] [pc = phthalocyaninato(2 -)] to co-ordinate base molecules is well known and e.s.r. investigations on [Co(pc)] in basic solutions have been reported; 8 however, well characterized solid compounds have never been described. In the present paper, syntheses of 1 : 1 and 1 : 2 adducts of [Co(pc)] with pyridine (py) and 4-methylpyridine (4-Mepy) are described together with their vibrational, magnetic, and electronic properties ; the relation between planar and five-and six-co-ordination in such complexes has also been investigated.
EXPERIMENTAL
Synthesis ofComplexes.-Phthalocynninatocobalt (11) , [Co(pc)] . This complex was synthesized as previously d e ~c r i b e d , ~, ~ and both polymorphs, a and p, were obtained. PhthaZocyaninato(pyridine)cobaZt(II), [Co(pc) (py)]. A suspension of [Co(pc)], in either the ct or p form, was heated under reflux in purified pyridine until the solid was completely dissolved. After cooling to 100 O C , a blue amorphous powder similar to [Co(pc)] was obtained. The filtered solid was dried in vucuo (2 mmHg) to constant weight.Elemental and thermal analysis conclusively proved that a new complex, containing one py for each [Co(pc)] unit, had been obtained (see Table 1). The complex has a very low solubility and only dissolves in boiling py. Hence a better preparative method is to extract with
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