2.0 x 10-4 k2, M-' 6' 5.9 k2k3/k-2, M-2 s-I 1.3 x 103 1.3 X 10, K,, M-I 17 not obsdbReferences 39 and 40. This is not observed even though [CN-] is a factor of 1.5-36 higher than in the G3 study. strength occurs, which results in the shift of the d-d band to higher energy.The crystal field stabilization energy (CFSE) for the squareplanar ds nickel(I1) complex should be greater than that for the d9 copper(I1) complex. This is reflected in shorter bonds for the nickel complex. Recent crystal structures17 show that the average equatorial bond lengths are 1.83 A for Ni"(H-,Aib3)-compared to 1.92 A for Cd1(H-,Aib3)-. The stability constant for the copper(I1) complex is larger because electron-pairing energy is required to form the low-spin square-planar nickel(I1) complex. The d8 nickel(I1) system shows a greater increase in stability constant for the Aib,, relative to the G3 complex, as compared to d9 copper(I1) system. This can be attributed to the larger gain in CFSE for the nickel(I1) system as the donor strength of the ligand increases.The nickel(II1,II) and copper(II1,II) reduction potentials have been measured for the complexes of Aibj6,16 and G3.33,34 The ratios of the stabilities of the complexes of divalent nickel and copper with Aib, and G3 are now known. This information can be used to calculate the ratios ( R , eq 20-22) of the stabilities of the 81-21 81-21-c -2H' trivalent metal complexes of these two ligands. The R values follow the sequence Cu" ( << Cu"' (lo",). In other words, Ni111(H-zAib3) is over 5000 times more stable than Ni111(H-2G3), and Cu"'(H_,Aib3) is almost 1.6 million times more stable than Cu11'(H-,G3). Thus, the inductive effect of the six methyl groups on the copper(II1) complex is enormous. The enhanced stability is consistent with previous observations of the increased thermal stability of the nickel(II1) and copper(II1) complexes of Aib,, relative to that of the corresponding complexes of G3.6 and the large CFSE, which is expectedfor a d8 trivalent metal ion with a square-planar geometry.32The reaction of Nin(HzAib3)-with cyanide ion is also markedly slower than the corresponding reaction of Ni"(H,G,)-. The values of the resolved rate constants for the reactions of both of these complexes with cyanide ion are given in Table VII. These complexes both rapidly form stable 1 : 1, cyanide ion mixed-ligand intermediates. The complexes react by a similar mechanism, with a rate step that depends on [CN-],, which carries the major portion of the reaction. The third-order rate constant for this process, kZk3/k+ as defined in eq 19, is -100 times smaller for the Aib, complex than the corresponding value for Ni"(H-,G,)-. In the case of the G3 complex, there is kinetic evidence for the formation of significant concentrations of a second intermediate, Ni"-(H-,G3)(CN-)>-. In the present study, there is no evidence for the formation of such a species, despite the use of cyanide concentrations up to 36 times that used in the G3 study. The failure to observe a second intermediate is presumably due to...

SUMMARYA mixture of DG[2Hg]~-inositol-1-and -4-phosphate and (meso) ~n~&nositol-Z and -5-phosphate is readily repared on a 100 milligram scale from the mixed isomers of The deblocked [ 2 H~]~-i n o s i t o l monophosphate isomers are obtained where the relative amounts of racemic m-inositol-1-phosphate > -4-phosphate > -2-phosphate > -5-phosphate. In addition a simple synthesis of DL-m-inositol-1-phosphate was developed which was found to be unsatisfactory for the preparation of deuterium-labeled product.di-Q-cyclohexylidene-[ f Hg]w-inositol by phosphorylation with tetrabenzylpyrophosphate.

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274ChemInform Abstract The meso-rhodin ester and the corresponding acid were prepared from meso-porphyrin IX dimethyl ester by an intramolecular Friedel-Crafts reaction following a known procedure. Both compounds were separated by preparative TLC. The Fe(III) complexes were prepared by a literature method. The investigation of all the compounds by means of UV, IR, 1H NMR and FAB mass spectrometry indicated that these species were synthesized as equimolar mixtures of the two isomers (I) and (II). Some separation of the isomers of (Ia)/(IIa) could be achieved by semipreparative HPLC. Even at 300 MHz, the two isomers of the free bases have very similar spectra. However, the difference between the two isomers is cleanly seen in the spectra of the Fe complexes, mixtures of the isomers can therefore be characterized in the complexed forms (no yields given).