aeH(3), 9.9 G (H(l) is cis to the a H). The calculation confirms the large -proton interaction and small /3-proton interaction, as the /3-proton coupling would be the same for all ß protons in a freely rotating methyl group, and hence the calculation yields extremes.

The thermally stable phosphinocopper(I) hydride cluster H8Cu8(PPh3)8 has been prepared from the reaction of (PPh3CuCl)4 and sodium trimethoxyborohydride in dimethylformamide (DMF). It crystallizes from DMF as H8Cue(PPh3)8• DMF in the centrosymmetric orthorhombic space group Pbca (Zk/,15; No. 61) with a = 40.10 ± 0.04, b = 22.46 ± 0.02, c ~21.86 ± 0.02 Á, and Z = 8. Observed and calculated densities are 1.367 ± 0.005 and 1.368 g cm-3, respectively. A single-crystal X-ray diffraction study based on counter data (sin 9max = 0.65, Cu Ka radiation) has led to the location of all 125 nonhydrogen atoms, the final discrepancy index being Rf = 9.2% for 3180 independent nonzero reflections. The crystal consists of discrete molecular units of H8Cu8(PPh3)8 and DMF, mutually separated by normal van der Waals distances. The H6Cue(PPh3)6 molecule contains a (slightly distorted) octahedral cluster of copper atoms. Two mutually trans faces of this octahedron are enlarged with their copper-copper distances ranging from 2.632 (6) to 2.674 (5) and averaging 2.655 ± 0,017 Á, while the remaining six copper-copper bond lengths range from 2.494 (6) to 2.595 (5), averaging 2.542 ± 0.044 Á. Each copper atom is apically bonded to a triphenylphosphine ligand with copper-phosphorus distances varying from 2.217 (7) to 2.262 (7), averaging 2.240 ± 0.017 A. Decomposition of the complex with CeHsCChD yields Ha and HD (but no D2) in varying proportions. An assay of liberated [ ]hydrogen indicates that the cluster is associated with six hydride ligands.Possible sites for these ligands (which were not located from the diffraction study) are discussed.

7 2 ir5* at 273 nm (/ = 0.29), and m -5* at 232 nm (/ = 0). These Xmax values are in good agreement with the observed spectrum of hexaphenylpentalene1 23456 (Xx 720 nm (log e 1.95), X2 380 nm (log e 3.99), and X3 310 nm (log e 4.52)) if one assumes that the presence of the phenyl groups shifts each peak to lower energy ( 14) There is some uncertainty as to whether the 285-nm band is due to methylpentalene or to its dimer.'

The reaction of azulene with Ru3(CO)12 leads, inter alia, to the formation of azulenetriruthenium heptacarbonyl, (C,pH?)Ru3(CO),, whose identity and stereochemistry have been elucidated via a single-crystal X-ray diffraction study. The complex is obtained as thin red plates crystallizing in the centrosymmetric monoclinic space group P2,/c (Clhs; No. 14) with ß = 17.183 (8_), b = 13.357 (11), and c = 16.410 (5) A; ß = 108.7 (1)°; p0bsd. = 2.19 (3) and pcalcd = 2.336 g cm"3 for = 627.46 and Z = 8. The structure was solved by means of Patterson and Fourier syntheses and was refined, by the method of least squares, to a final discrepancy index of Rp = 8.9% for 2285 independent nonzero reflections (Mo radiation; sin 0max = 0.36) collected with a Supper-Pace automated diffractometer. The two (C10H8)-Ru3(CO), molecules which define the crystallographic asymmetric unit are equivalent and have Cs symmetry within the limits of experimental error. Within each molecule the three ruthenium atoms define an isosceles triangle with Ru(l)-Ru(2) = Ru(l)-Ru(3) = 2.937 (4)-2.949 (4) and Ru(2)-Ru(3) = 2.740 (4)-2.741 (4) A. Each ruthenium atom is bonded to two terminal carbonyl ligands, with the seventh carbonyl group symmetrically bridging Ru(2) and Ru(3). Atom Ru(l) interacts with all atoms of the five-membered carbocyclic ring of the azulene ligand; Ru(2) and Ru(3) lie below the seven-membered ring and are linked, in a delocalized manner, to the remaining five carbon atoms of the azulene system.Relationships between (C10H8)Ru3(CO), and the tetrahedral cluster complex [(CH3)3C10H5]Ru4(CO)9 are also discussed.

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