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The structures of the large neutral boranes 2,2'-bi(nido-decaboranyl), 2,2'-(B10H13)2, m.p. 178 "C, and 2,6'bi(nido-decaboranyl), 2,6'-( B,0H13),, m.p. 154 "C, have been established by single-crystal X-ray diffraction.The 2,2' isomer is tetragonal, space group /4,cd, with a = 11.901 (3), c = 23.1 35(4) A, molecular symmetry Cz ; the 2,6' isomer is orthorhombic, space group Pbca, with a = 14.673(3), b = 19.765(4), and c = 11.580(3) A.The intercluster B-B bond lengths are respectively 1.692(3) and 1.679(3) A, and there is a lengthening of 0.01 5 A of the adjacent cluster B-B distances when compared with the corresponding distances in decaborane(l4) itself.The lH-{llB) and llB n.m.r. behaviour of the two isomeric conjuncto-boranes has been investigated and the results for the 2 2 ' isomer are discussed in some detail. Infrared and U.V. spectroscopic data are presented. The unambiguous determination of the structures permits a discussion of possible synthetic mechanisms. 1980 791 26 nimol) recovered by sublimation at ca. 60 "C (15 Pa).

The oxime of isopropyl phenyl ketone (2-isomer) with NaOAc-Na,PdCl, gives [Pd,(ON=CPr*Ph),] and whereas pinacolone oxime carbopalladates regiospecifically on the t-butyl group, the dimethylhydrazone carbopalladates only on the methyl group: acetone oxime 0-ally1 ether palladates on the central carbon atom of the ally1 group with nucleophilic attack (e.g. by OMe-) on the terminal carbon atom.

The crystal structures of triphenylgallium and triphenylindium have been determined. Both compounds crystallise with Z = 4 in a unit cell of space group Pbcn, but they are not iso-structural. In the indium compound short intermolecular contacts suggest that weak association occurs by donation of electrons from a phenyl group of one molecule to the vacant p-orbital of indium in another molecule. Similar but weaker association may also occur in the gallium compound.TRIMETHYLALUMINIUM is dimeric in the solid state,l the association being either by way of three-centre bonds or through A1-C-H A1 bridges.3 We have shown that triphenylaluminium is also dimeric, with bridging phenyl groups. In the crystal of dimethylphenylaluminium ti the dimers have phenyl bridges, which indicates that phenyl is a better bridging group than is methyl. In the iso-structural crystals of trimethylindium and trimethylthallium weak inter-molecular bonds occur, such that the approximately trigonalplanar molecules make short contacts with methyl groups of neighbouring molecules, each metal atom thereby achieving trigonal-bipyramidal co-ordination. If the greater bridging tendency of phenyl relative to methyl extends to Group I11 metals other than aluminium, then the triphenyl complexes of gallium, indium, and thallium might be expected to associate in the solid state, and we have therefore investigated the crystal structures of triphenyl-gallium and -indium.