Reaction of Ru3(CO)42 with tetraphenylporphine and tetra-p-isopropylphenylporphine affords ruthe-nium^!) carbonyl-porphine complexes which in past investigations have been formulated as the monocarbonyls Ru(CO)(TPP) and Ru(CO)O'-Pr-TPP), respectively. A recent X-ray study of the tetraphenylporphine reaction product recrystallized from chloroform-ethanol has led to reformulation of this product as the dicarbonyl Ru(CO)2(TPP), containing markedly bent (154°) Ru-C-O bonds. The nature of these compounds after recrystallization from chloroform-ethanol has been reinvestigated. Chemical and spectroscopic experiments show (i) no CO evolution when monopyridinates are formed with excess pyridine, (ii) no mass spectral peaks due to dicarbonyl ions such as Ru(CO)2TPP+, (iii) an ABCD pattern of phenyl o-H and m-H pmr signals (z-Pr-TPP complex) which collapses to an AA'BB' pattern at elevated temperatures, (iv) methyl and methylene pmr signals (z-Pr-TPP complex) whose chemical shifts are indicative of axially coordinated ethanol. These observations are incompatible with the dicarbonyl description but are consistent with the formulations Ru(CO)(TPP)(EtOH) and Ru(CO)(z-Pr-TPP)(EtOH). The composition and structure of the TPP reaction product has been confirmed by an X-ray determination. The compound Ru(CO)(TPP)(EtOH) crystallizes in space group C2-PI of the triclinic system in a cell of dimensions a = 10.078 (4), b = 11.819 (5), c = 8.883 (4) Á; a = 101.37 (5), ß = 106.12 (4), and y = 65.91 (3)°. A density of 1.416 g cm-3 calculated for one molecule in the unit cell agrees with that of 1.39 (1) g cm™3 observed by flotation of the crystals in aqueous ZnCl2. The structure has been solved and refined by standard methods, based on 2906 unique reflections collected by counter methods using monochromatized Mo Ka radiation. The final agreement index is 7.5%. The molecule has crystallographically imposed T symmetry and hence the CO and EtOH groups are disordered and the RuN4 portion of the molecule is planar. The overall deviations from planarity of the porphinato core are very small. The distances within the porphinato core are in good agreement with those reported for other metalloporphyrins. The Ru-O(Et) distance is 2.21 (2) A, and the EtOH group has its expected geometry. The Ru-C (of CO) distance is 1.77 (2) Á and the Ru-C-O bond is essentially linear, the bond angle being 175.8 (1.9)°.In recent years the range of metalloporphine and porphyrin complexes has been expanded by the synthesis of species containing second-and third-row transition metal ions,3 including ruthenium(II, III).4-11(1) Northwestern University.(2) Massachusetts Institute of Technology.(3) P.

The structure of histamine free base has been determined from three-dimensional X-ray data, collected by counter methods. The tautomer obtained in the solid state by recrystallization from benzene is 5-(2aminoethyl)imidazole, with no evidence for the coexistence of 4-(2-aminoethyl)imidazole. The imidazole and NH2 groups are trans to one another across the C-C bond of the ethyl group. The nitrogen and carbon atoms of the imidazole ring are coplanar. The dihedral angle between this plane and the plane of the carbon and nitrogen atoms of the aminoethyl side chain is 66.3°. Distances within the molecule are in good agreement with recent X-ray and neutron diffraction results on the orthorhombic form of L-histidine, despite the fact that orthorhombic lhistidine is a derivative of 4-ethylimidiazole, rather than 5-ethylimidazole. In histamine free base there is an -• • -N hydrogen bond involving the N-H function of the imidazole ring with the NH2 group on the side chain of an adjacent molecule. In this way infinite zig-zag chains of imidazole molecules are formed in the crystal. Histamine free base cry stallizesin space group C22-P2i of the monoclinic system, in a cell of dimensions a = 7.249 (2), b = 7.634 (3), c = 5.698 (2) A, and ß = 104.96 (2)°. A density of 1.218 g/cm3 45678910calculated for two molecules in the unit cell agrees with that of 1.20 (1) g/cm3 observed by flotation in an ethyl benzoate-iodobenzene medium. A total of 548 unique reflections was collected using Cu Ka X-radiation, prefiltered with Ni foil. The structure was solved by direct methods and refined by least-squares methods to a final agreement index on Fof 3.1 %.

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