Packing and Isomorphous Series

It seems clear that all cases of structure control by crystal packing effects are unlikely to be noted much less proven. However, we think that the probable importance of the concept can be buttressed by noting effects that can be catalogued under this general rubric. In this section we will note the occurrence of a number of complexes having, after appropriate cell reduction, similar cell constants and form isomorphous series. We will comment on members of the series that have features that are reasonably ascribed to crystal packing effects. We start with the highest symmetry crystal systems and work towards the triclinic systems. 

The isomorphous series (b) that has members that differ only in the nature of the anion (BFJ or CIOJ) would be reasonably expected. However, the occurence of the o-bonded phenyl complex in this series is unexpected. All remaining members of the series in the monoclinic systems do not appear unusual or unexpected in any sense. 

The first two isomorphous groups listed in Table XXVIII may be noted to have one complex common to both Ni(OEP). Members of the two series differ in the extent of their n-n interactions members of the first series were catalogued into Group W and members of the second series into Group I. The obvious question of why Ni(OEP) crystallizes in both series is not clear, however, preliminary evidence suggests that the occurence of the compound in the first series results from a template effect. In our hands the first crystalline form of Ni(OEP) is found to always contain small amounts of HjOEP the second contains less or none. Further work is needed to completely clarify the matter. The crystal packing effects of the third series were mentioned earlier and are detailed elsewhere  

5-DiEtMeBPheod 4,5-diethyl methylbacteriopheophorbide d mesoporphyrin IX dimethyl ester Methyl Pheophorbide a Ethyl Chlorophyllide a or b Methyl Chlorophyllide a Methyl Pyrochlorophyllide a 3-vinyl-8-(E-2-nitrovinyl-l)deutero monoanion of 21-Methyl-5,10,15,20-tetraphenylporphyrin monoanion of 21-Phenyl-5,10,15,20-tetraphenylporphyrin dianion of 5,15-dimethyl-2,3,7,8,12,13,17,18-octaethylporphyrin 

HaMeso IX DME MePheo a Mg(EtChl a, b) Mg(MeChl a) Mg(MePyrChl a) NOaProto IX DME N-CH3TPP N-PhTPP ODM (P-N4) 

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