Platinum and rhenium phosphine carbonyl thiolate complexes

The heterometallic complex (CO)₃(PPh₃)Re(μ-SPr)Pt(PPh₃)(CO) (I) was formed in the reaction of Re₂(μ-SPr)₂(CO)₈ with (PPh₃)₂Pt(C₂Ph₂), together with (CO)₃(PPh₃)Re(μ-SPr)₂Re(CO)₄ (II), which was also prepared by an alternative synthesis. Compounds I and II were characterized by X-ray diffraction. In I, the Re-Pt single bond, 2.7414(5) Å, is supplemented by a thiolate bridge with shortened bonds: Pt-S (2.336(2) Å) and Re-S (2.449(2) Å). The Re-P (2.469(2) Å) and Pt-P (2.329(2) Å) bonds are also shortened. Complex II resulting from replacement of one CO group in the starting rhenium complex by triphenylphosphine has no M-M bond, and the Re-S and Re-P bond lengths (2.511(2)–2.527(2) and 2.517(3) Å) are close to the length of single bonds. It is assumed that the platinum atom in I is attached to the formally double bond Re ? SPr arising upon dissociation of Re₂(μ-SPr)₂(CO)₈.     

Phenyltellurium halide complexes of iron cyclopentadienyl dicarbonyl: Synthesis and molecular structures of CpFe(CO)2TePh, CpFe(CO)2TeBr2Ph, CpFe(CO)2TeBrPh(μ-Br)Br3TePh, and PhTeI3(C4H8O)

The bromination of CpFe(CO)₂TePh (I) affords the monomeric complex CpFe(CO)₂TePhBr₂ (II) as the major product and crystals (III), being a cocrystallizate of complexes II and CpFe(CO)₂TeBrPh(μ-Br)TePhBr₃ (IIIA). Complex IIIA contains a PhTeBr₃ molecule, which is weakly bound because of the lone electron pair (LEP) of the bridging bromine atom of molecule II. An analogous weak interaction with the LEP of oxygen in tetrahydrofuran (Te…O 2.893 ?) is observed in the PhTeI₃(THF) adduct (IV), which is a dimer with two bridging iodine atoms and can be obtained by the crystallization of PhTeI₃ from THF. According to the X-ray diffraction data, the Fe-Te distances in compounds II and IIIA (on the average, 2.5 ?) differ slightly and are similarly shortened by 0.2 ? compared to the sum of the covalent radii of iron and tellurium. The secondary interactions Te…halide and Te…π system of the phenyl ligand are discussed. Original Russian Text ? Yu.V. Torubaev, A.A. Pasynskii, I.V. Skabitskii, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 5, pp. 347–352.     

Synthesis and structure of mixed-metal thiolate complex Cp′Cr(CO)2(μ-SBu)Pt(PPh3)2: Side-on-coordination of Cr-S double bond with platinum

The reaction of [Cp′Cr(CO)₂(μ-SBu)]₂ (1) (Cp′ = MeC₅H₄) with (PPh₃)₂Pt(PhCCPh) gives Cp′Cr(CO)₂(μ-SBu)Pt(PPh₃)₂ (2) which could be regarded as a product of the substitution of acetylene ligand at platinum by a monomeric chromium-thiolate fragment. According to the X-ray diffraction analysis 2 contains single Cr-Pt (2.7538(15)) and Pt-S (2.294(2) Å) bonds while Cr-S bond (2.274(3) Å) is shortened in comparison with ordinary Cr-S bonds (2.4107(4)-2.4311(4) Å) in 1. The bonding between Cr-S fragment and platinum atom is similar to the olefine coordination in their platinum complexes.     

Electro-elastic interactions and second order anisotropic constitutive equations

Piezoelectricity is usually expressed as an interaction between mechanical and electrical variables. The physics involved is hence governed by a coupling between Maxwell's equations of electromagnetism and the equations of elasticity. Such a coupling takes us through the piezoelectric constitutive relations. In this work, the second order anisotropic constitutive equations are treated, and in particular, the number of independent material constants is computed for all the 32 crystallographic classes.Paper presented, in reduced version, at the 12th Italian National Congress of Theoretical and Applied Mechanics (AIMETA '95), October 1995, Naples, Italy.     

Transition to Chaos in the Floating Half Zone Convection

The transition process from steady convection to chaos is experimentally studied in thermocapillary convections of floating half zone. The onset of temperature oscillations in the liquid bridge of floating half zone and further transitions of the temporal convective behaviour are detected by measuring the temperature in the liquid bridge. The fast Fourier transform reveals the frequency and amplitude characteristics of the flow transition. The experimental results indicate the existence of a sequence of period-doubling bifurcations that culminate in chaos. The measured Feigenbaum numbers are δ2 =4.69 and δ4 = 4.6, which are comparable with the theoretical asymptotic value δ=4.669.