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The crystal structure of dimethylsulfoxidepentammineruthenium (11)

Complexes have been formed between bivalent ions of cobalt, nickel, copper, zinc, mercury, and palladium and the the ligands 4,4'-dicarboxyethyl-3,3',5,5'-tetramethyldipyrromethene (mpmH) and 3,4'-dicarboxyethyl-5-chloro-3',4,5'-trimethyldipyrromethene (cpmH). The stereochemistry of these complexes has been investigated by measurement of magnetic susceptibility, and l H n.m.r. spectra, and U.V. visible spectra. An X-ray determination of the crystal and molecular structure of the complex Pd(mpm), is reported. The palladium atom lies on a crystallographic centre of symmetry and is necessarily coplanar with the four co-ordinated nitrogen atoms of the ligand. The unique bidentate ligand is not planar.THE stereochemistry of transition-metal complexes of dipyrromethenes has been much discussed. Porter,l who reported the preparation of bis(dipyrr0methene) complexes of the divalent ions of cobalt, nickel, palladium, copper, zinc, cadmium, and mercury concluded that steric interactions between groups in the 5-and 5'positions (I) precluded square planar stereochemistry for the metal ions. f 11Recent work has established that some metal ions will achieve tetrahedral configurations in order to overcome intermolecular steric repulsions. from studies of u.v.-visible spectra and magnetism, that It has been t Part I, J. E. Fergusson and C.

The structure of the title compound has been determined by X-ray methods. Crystals are monoclinic, space group P2,lc. with Z = 4 in a unit cell of dimensions a = 18.750(3), b = 10.108(2), c = 18.927(3) A, p = 92.19(1)".The structure was solved by the heavy-atom method and refined by block-diagonal least-squares methods to a residual R of 0.070 for 31 45 data considered observed. The structure contains well separated discrete molecules. The two bismuth atoms are linked by an oxygen bridge [mean Bi-O(br) 2.065(10) 8. Bi-O-Bi 142.4(7)"]. The configuration about the bismuth atoms is distorted trigonal bipyramidal with the oxygen atoms apical and phenyl groups equatorial. The perchlorate groups are weakly co-ordinated to the metal [mean Bi-O(perch1orate) 2.65(1) A], one being disordered. Other mean dimensions: Bi-C(Ph) 2.1 9(2) A, O(br)-Bi-C(Ph) 97.1 (I)", Bi-O-CI 132.3(8)'. N1G 2W1 THE class of compounds X*RIR,-O-RIR,*X (1; R = Ph or Me, 31 = Sb or Bi, X = halide, NO,, or pseudohalide) are well known,2-8 and their i.r. and conductance data have been interpreted in favour of non-ionic structures containing five-co-ordinate antimony and bismuth. A recent crystal structure analysis 2,3 has shown that for the compound [(Ph3Sb(N3)}20] coordination about the metal is close to regular trigonal bipyramidal. On the other hand, tetrahedral coordination about the metal, with ionic perchlorate groups, had been suggested, from i.r. studies, for [[R,Sb(ClO,)},O] iR = Ph (ref. 8) or Me (ref. 9):. reinvestigation of the i.r. spectra of these compounds and of [(Ph,Bi(ClO,)),O]and their hydrates has led to the postulation that the anhydrous perchlorate compounds have structures 4niilar to those of the series of compounds (l), and an S-ray analysis lo has established that [(Me3Sb(C10,)},0] also has a trigonal bipyramidal configuration at the Sb atoms. Since crystals of the anhydrous antimony compound could not be obtained in a satisfactory form, we have investigated the structure of the title bismuth compound in order to elucidate the stereochemistry at the metal atom and the nature of the perchlorate group environment in the solid. EXPERIMENTAL

The crystal structure of triphenylarsenic difluoride has been determined from three-dimensional X-ray diffractometer data. Crystals of Ph3AsF2 are orthorhombic, space group Pbcn, with four molecules of C18H15AsF2 in a unit cell of dimensions a = 6.270, b = 16.593, c = 14.519 Å; molecular symmetry C2 is required. The structure was solved by the heavy atom method and refined by full-matrix least-squares calculations to a final residual R of 0.054 for 979 intensities regarded as "observed" (I > 3σ(I)). The crystals contain well separated discrete molecules. The arsenic atom has near regular trigonal bipyramidal geometry with apical fluorine atoms (As—F 1.834(7) Å) and equatorial phenyl rings (mean As—C 1.925(5) Å). Idealized D3 symmetry is not achieved because of unequal rotations of the phenyl rings about the As—C bonds.