WILL[AMS. Can. J. Chem. 62, 755 (1984). The ruthenium(l1) porphyrin complex R U ( O E P ) ( P P~~)~ (OEP = the dianion of octaethylporphyrin) has been prepared from Ru(OEP)(CO)EtOH, and the X-ray crystal structure determined; as expected, the six-coordinate ruthenium is situated in the porphyrin plane and has two axial phosphine ligands. Synthesized also from the carbonyl(ethano1) precursors were the corresponding tris(p-methoxypheny1)phosphine complex. and the Ru(TPP)L, (TPP = the dianion of tetraphenylporphyrin, L = PPh,, P(p-CH30C6H,),, PnBu3) and Ru(TPP)(CO)PPh3 complexes. Optical and 'H nmr data are presented for the complexes in solution. In some cases dissociation of a phosphine ligand to generate five-coordinate species occurs and this has been studied quantitatively in toluene at 20°C for the Ru(OEP)L2 and Ru(TPP)L2 systems. ~ Introduction Our continuing interest in, and development of, ruthenium porphyrin chemistry (1) led us to discover that ruthenium(I1) porphyrins containing tertiary phosphines as axial ligands were efficient catalysts for the decarbonylation of aldehydes (2), as well as for oxidation of substrates such as phosphines and sulfides by molecular oxygen through generation of hydrogen peroxide (3). The complexes also undergo two successive oneelectron electrochemical oxidations to yield first a ruthenium(11I) bisphosphine cation and then a ruthenium(II1) r-cation radical (4).We report here the details of the preparation and characterization of some of the ruthenium porphyrin -tertiary phosphine complexes, including the X-ray structure of RU(OEP)(PP~~),.? The dissociative equilibrium involving the loss of a phosphine ligand from the Ru(porp)L,, L = PPh,, P(p-CH30C6H4)3, complexes in toluene solution is also considered. Other groups ( 5 , 6) have described the synthesis of Ru-(TPP)(PPh,),, but the reported solution optical spectral data did not make allowance for the dissociation of phosphine.

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. Can. J. Chem. 64, 2440 (1 986).The rhodium(II1) octaethylporphyrin complex Rh(OEP)(PPh3)C1 (I) has been synthesized via Rh(II1) or Rh(1) precursors, and fully characterized both by spectroscopy and single~rystal data. The crystals, available as a bis(ch1oroform) solvate are triclinic, P1, a = 13.478(5), b = 14.300(5), c = 15.346(4)A, a = 102.33(2), P = 102.89(2), y = 90.56(3)", Z = 2, D, = 1.384gcm-'.The structure was determined from Mo diffractometer data and refined by least-squa;es methods to R = 0.095, R,. = 0.068 for 5189 reflections. The octahedrally coordinated rhodium atom is displaced by 0.077 A from the mean plane of thq four N atoms, towards the triphenylphosphine group. The average Rh -ring nitrogen distance is 2.024 A, Rh-P is 2.306 (3) [Traduit par la revue]

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Doubly vs. singly hydrogen-bonded arrangements in crystalline N-acylated amino acids R-CONH-CHR'-C02H are examined by energy calculations. The O(amide) is a significantly stronger proton acceptor than the O(carboxy1). Thus in one-third of the crystal structures the molecules form doubly hydrogen-bonded systems O-H-.O(amide) and N-H-O(amide), despite the general preference for the maximum number of proton acceptor sites to participate in hydrogen bonds, dictated by molecular packing and conformation. The energy results are consistent with the tendency for the molecules to be interlinked via single hydrogen bonds O-H-O(amide) and N-H-.O(carboxyl), rather than the reverse, and the total absence of the doubly hydrogen-bonded systems 0-H-O(carboxy1) and N-H-(carboxyl).