Metal derivatives of azoles,part VII. Pyrazolato-bridged dinuclear complexes containing either cyclopalladated or -platinated trimesitylphosphine or -arsine

Summary The halogen bridges of the dimeric, cyclometallated trimesityl-arsine and -phosphine complexes of palladium(II) and platinum(II), where M=Pd or Pt and E=P or As have been replaced with pyrazolate groups to give the corresponding and less symmetric pyrazolato-bridged complexes, where M=Pd or Pt, E=P or As, Pz=pyrazolato anion, and M=Pd, E=As, Pz=3,5-dimethylpyrazolato anion. In the case of the palladium complexes,¹H. n.m.r. clearly indicates the presence of only one isomer which is most likely to have thetrans configuration while the platinum complexes are mixtures of bothcis andtrans forms.Part VI, ref. 3c     

Bis(trimethylphosphine)silver(I) hexafluorophosphate

In the title two‐coordinate silver compound, [Ag(C₃­H₉­P)₂]­PF₆, the cation has crystallographically imposed mirror symmetry, and approximates very closely to m (D_3d) symmetry with fully staggered methyl groups in the solid state. The Ag atom has a nearly linear coordination geometry, with a P—Ag—P angle of 178.70 (4)°. The Ag—P bond lengths are 2.3746 (12) and 2.3783 (12) Å, which are ­significantly longer than the Au—P bond length of 2.304 (1) Å in the analogous two‐coordinate gold cation. The lack of intra­molecular steric effects within the present cations containing tri­methyl­phosphine (cone angle 118°), compared with those in known cations containing trimesityl­phosphine (cone angle 212°), provides a better comparison of M—P distances and thus more conclusive evidence that Au really is smaller than Ag.     

The molecular structure of gaseous bis(hexamethydisilylamido)mercury(II), Hg{N(Si(CH3)3)2}2, as determined by electron diffraction

Gaseous bis(hexamethydisilylamido)mercury(II), Hg{N(SiMe₃)₂)₂}₂, has been studied by electron diffraction at a nozzle temperature of ca 390 K.

The diffraction data are consistent with a model consisting only of monomers. By assuming the NHgN chain to be linear and the HgHSi₂ fragments to be planar, an equilibrium conformer with a staggered Si₂NHgNSi₂ skeleton of D_ad-symmetry may be brought into a nice agreement with the observed diffraction data. The relatively large value of the vibrational amplitude of the inter-ligand SiSi distance, 0.26(12) A, indicates that the ligands undergo large amplitude vibrations about the NHgN axis. Steric considerations as well as the magnitude of the rotational barrier as estimated from the diffraction data (ca. 2 kcal mol⁻¹) show that this motion is hindered. A model with an eclipsed, co-planar Si₂NHgNSi₂ backbone of D_adsymmetry could not satisfactorily be brought into agreement with the observed diffraction data.

The values of some relevant key-parameters are: r_a(Hg---N) = 2.01(2) A, r_a(Si---N) = 1.732(9) A, r_a(Si---C) = 1.883(6) A;HgNSi = 116.0(1.0)°, SiNSi = 128.0(2.0)°, NSiC= 111.8(1.2)° and SiCH = 111.0(2.0)°. The trimethylsilyl groups are twisted 25(3)° away from their references positions typified by one Si---C bond of each such group eclipsing the adjacent Hg---N bond, in such a way that the overall symmetry of the model is lowered from D_ad to S₄.     

Scaling in soft hadroproduction by positive projectiles in the range of 32–147 GeV/c

The total hadron multiplicity and the multiplicity in the three-jet events ine ⁺ e ^?-annihilation are considered. The formula for the total multiplicity (with account for the heavy quark contribution) agrees well with experiment. The value of the multiplicity for three-jet events is predicted.     

Structure of chlorotris(1,3,5-triaza-7-phosphaadamantane)platinum(II) chloride hydrate methanolate, [Pt(PTA)3Cl] [Cl]·H2O·CH3OH

The title compound chlorotris(PTA)platinum(II) chloride hydrate methanolate (PTA=1,3,5-triaza-7-phosphaadamantane), [C₁₉H₄₂Cl₂N₉O₂P₃Pt] is monoclinic, witha=10.832(1),b=21.306(7),c=12.702(3)Å,=100.42(5)°,V=2883(2)ų,Z=4,D _x=1.814 g cm^–3,=53.0 cm^–1,F(000)=1568,T=298K in space groupP2₁/c. The structure was solved by heavy atom and Fourier methods and refined toR=0.051 for 4319 unique observed reflections. The complex exhibits approximately square-planar geometry about the Pt atom and a significant trans effect, with bond lengths Pt-Cl1=2.3371(2), Pt-C12 (ionic)=4.463(4), Pt-P _{trans(to cl)}=2.233(2), Pt-P _cis,ave=2.323(3)Å and bond angles Cl-Pt-P _cisave 83.60(3), P _trans -Pt-P _cis,ave 96.49(6)°. The H₂O is apparently hydrogen bonded to two N atoms on different cations, and the methanol OH group to the chloride anion.