The 1 : 1 reaction between PRC12 (R = C,H, Me,4,6) and (Me,Si)2S in toluene yields (RPS)4 (1) which slowly disproportionates under mild conditions ( 3 5 -4 0 "C, 3 d) to (RPSZ)2 ( 2 ) . Both structures have been determined by X-ray diffraction. Compound (1 ) is monoclinic, space group Cc, with a = 2 299.3( 7), b = 1 167.9(3), c = 1 937.8(6) pm, S = 130.65(2)", and Z = 4; R = 0.050 for 3 209 unique observed reflections. The eight-membered (PS), ring adopts the crown conformation but is disordered. Compound ( 2 ) is monoclinic, space group P2,/c, with a = 890.1 (2), b = 1 845.2( 12), c = 641.3(1) pm, p = 98.74(1)", and 2 = 2; R = 0.062 for 904 unique observed reflections. The four-membered ring with two trans exocyclic sulphurs possesses a crystallographic centre of symmetry.Very few phosphorus-sulphur ring compounds of the type (RPS), are described in the literature: (PhPS)3 has been shown l o 2 to contain a five-membered ring, with one exocyclic P a , and Lappert and co-workers reported a six-membered (Rps)3 ring with R = C6H2But3-2,4,6. In the courw of our study of the reactions of organosilicon and organotin sulphides with phosphorus-halogen bonds, which enable phosphorus sulphides to be prepared under very mild conditions, we have synthesised a compound with the composition (RPS), (1 ; R = C6H2Me3-2,4,6 = mesityl). The molecular ion peak could not be observed in the mass spectrum and the proton-decoupled jlP n.m.r. spectrum showed only a single line, so a crystal structure determination was required to establish the size of the PS ring. On warming a solution of compound (l), white crystals of (RPS2)2 (2; R = C6H2Me3-2,4,6) separated, which were also employed for Xray structure elucidation. ExperimentalPhosphorus-31 n.m.r. spectra were recorded on a Bruker W P 80 SY Fourier-transform spectrometer with 85% &Po4 as external standard, mass spectra by electronic ionisation (e.i.) and field desorption (f.d.) at 70 eV (1.12 x lo-'' J) on a Varian CH5 spectrometer. Solvents were dried and distilled before use. Elemental analyses were performed by Beller in Gottingen.

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Abstract The Compound [S(AUPPh3)2] · CH2Cl2 was prepared from Ph3PAuCl and H2S in CH2Cl2 and characterised by X-ray structure determination [P21/c, a = 1851.6(4), b = 2225.1(6), c = 880.3(2) pm, β = 96.32(1)°, Z = 4, R = 0.053]. A constrained refinement of the light atom positions was necessary because of pseudosymmetry. Ph3PAuPF6 reacts with Se(Sn)(CH3)3)2 to give [Se(AuPPh3)3]+PF6- which was also characterised by X-ray methods [P1̄, a = 1539.5(6), b = 1800.5(7), c = 2289.5(9) pm, α = 89.35(3), β = 72.44(3), γ = 69.75(3)°, Z = 4, R = 0.061]. There are two formula units in the asymmetric unit. Both structures show short Au···Au contacts (ca. 300-340 pm).

AbstractThe nature of the products which are formed in the reaction of tris(trimethylsilyl)Methylfluorosilanes (Me3Si)3C -SiF2R with KOH depends on the bulkiness of the substituents R. The condensed siloxane is obtained for R = F . The crystal structure determination of this siloxane (Me3Si)3C -SiF2-O -SiF2-C (SiMe3)3 shows that the Si -O - Si unit is linear. A fluorosilanol as well as a siloxane could be isolated for R = Me. 1,3-Migration of one or two trimethylsilyl groups from the carbon to the oxygen takes place for R = phenyl, rm-butyl or silylamine, with formation of siloxanes which are isomeres o f the expected silanols.