ZnTPP + L: ^L:ZnTPP (6) cases cannot be assigned merely to "noncoordinating" vs "coordinating" solvents since there are at least six AD and AHD solvents in common to the regressions in both eq 4 and eq 5.Clearly, solvent dipolarity has an important role in each instance of the solvent shifting the Soret peak even though the size of that shift is smaller for NiPPDME. On the other hand, for NiPPDME in the presence of strong EPD solvents (i.e., piperidine) in which nickel assumes a higher C.N., the Soret band shows a large red shift not unlike ZnTPP with ligands of comparable basicity.9 Just as Nappa and Valentine observed for ZnTPP,8 the Soret band

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with our experimental value of 0.044 is therefore undoubtedly fortuitous, but clearly the calculation tends to support a much lower yield than the 0.18-0.19 values usually employed. A new absolute determination of the quantum yield is strongly suggested by these studies.

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Ortho-, meta-and para-isomers of N-(pyrimidin-4-yl)aminobenzoic acid and their methyl esters were investigated by electron impact mass spectrometry. Their fragmentation was found to be strongly dependent on the position of the substituent in the aminobenzoic moiety. Two different kinds of ortho effect were studied and confirmed with the aid of deuterium-labelled derivatives.