Reactions of π-cyclopentadienyltriphenylphosphinemetal diiodides and π-cyclopentadienylcarbonylmetal diiodides (M = Co,Rh, Ir) with 1,4-dilithio-1,2,3,4-tetraphenylbutadiene

Reactions between π-cyclopentadienyltriphenylphosphinemetàl diiodides (M = Rh and Ir) and 1,4-dilithio-l,2,3,4-tetraphenylbutadiene result in the formation of 1-(π-cyclopentadienyl)-l-triphenylphosphine-2,3,4,5-tetraphenylrhodole and 1-(π-cyclopentadienyl)-1-triphenylphosphine-2,3,4,5-tetraphenyliridole, respectively, in low yield. Reactions between π-cyclopentadienyltriphenylphosphinecobalt diiodide or π-cyclopentadienylcarbonylcobalt diiodide do not produce the expected cobaltacyclopentadiene complexes, but instead a low yield of π-cyclopentadienyl-(π-tetraphenylcyclobutadiene)cobalt. The trimeric rhodium complex (π-C₅H₅Rh)₃(CO)(PhCCPh) has been isolated from a reaction between 1,4-dilithio-l,2,3,4-tetraphenylbutadiene and π-cyclopentadienylcarbonylrhodium diiodide. The importance of metallocyclic intermediates in the formation of polynuclear complexes of this type is discussed.     

Side chain modified sterols as probes into insect molting hormone metabolism. I: synthesis of monofluorophytosterols

25- and 26-monofluorophytosterols were synthesized from stigmasterol as potential arthropod-activated competitive inhibitors of side chain hydroxylations occuring in ecdysone biogenesis.     

Sesquiterpenes from termite soldiers. Structure of amiteol,a new 5β, 7β, 10β-eudesmane from amitermesexcellens

The defense secretions of termite soldiers in the genera $\text{Amitermes}$, $\text{Noditermes}$, and $\text{Prorhinotermes}$ contain sesqueterpene hydrocarbons, alcohols and ethers. Three new eudesmanes possessing the hitherto unknown 5β, 7β, 10β configuration were identified from $\text{Amitermes}$$\text{excellens}$.     

Time-resolved fluorescence depolarization studies of rotational relaxation in viscous media

Rotational relaxation times (τ_roi) were measured for xanthene dyes in several n-alcohols, ethylene glycol and glycerol by following the fluorescence depolarization using a single photon counting technique. Additional studies were made of the fluidity of the hydrocarbon micellar interior using pyrene derivatives as fluorescent probes. While the correlation between τ_roi and viscosity for the smaller n-alcohols is good, as anticipated by the models of Stokes—Einstein—Debye and later Perrin, a saturation in this correlation is observed in more viscous systems in accordance with recent molecular dynamics calculations. The influence of molecular structure on both viscosity and rotational relaxation times is also discussed. Pyrene, 1-pyrene suphonic acid and 1-pyrene butyeric acid exhibit rapid reorientation τ_roi ? 10^?9 s, in glycerol and micellar systems.     

Reaction of carboxamide with Cu2Oisonitrile complex; formation of a new chelated copper(I) complex

Reaction of carboxamides with Cu₂O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu₂Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu₂Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described.     

Syntheses of metal carbonyls: XVII. Formation of a heteronuclear organometallic cluster containing ruthenium and rhodium; crystal and molecular structure of {[Rh(η-C5Me5)]3Ru(CO)3](μ3-CO)2}

Ru(C₆Me₆)(C₂H₄)₂ reacts with Rh(C₅Me₅)(CO)₂ to give the known dinuclear complex [Rh(C₅Me₅)(CO)]₂ and the new heteronuclear cluster complex {[Rh(C₅Me₅)]₃[Ru(CO)₃](μ₃-CO)₂} which has been fully characterized by a single crystal X-ray diffraction study.     

Crystal structure of dimeric p-phenoxyphenyltellurium(IV) trichloride

p-PhOC₆H₄TeCl₃ crystallises with a dimeric molecular unit. The two approximately square pyramidal coordination polyhedra are linked trans to each other through two bridging chlorine atoms. The dimeric units are further connected through Te…Cl secondary interactions producing a distorted octahedral geometry about each tellurium atom. The crystals are triclinic, space group P$\text{1}$, with unit cell dimensions a 8.521(2), b 10.917(2), c 14.813(2) Å, α 81.84(1), β 83.38(1), γ 88.41(1)°, V 1353.4(4) ų and Z = 2(dimers) from 3887 observed reflections [I > 3σ(I)], R = 0.0359.     

The compatibility of the cyano and alkyl chloride functions in phenylthioalkylation reactions of O-silylated enolates

The compatibility of the cyano group and of chlorides with the conditions of phenylthioalkylation O-sitylated enotates has been demonstrated.     

Cyclometallation reactions XII. On the effect of various leaving groups on internal metallation reactions with alkylmanganese complexes

The interaction of azobenzene and MnR(CO)₅ (R  Me, Et, CH₂Ph, CH₂-C₆Me₅, COCF₃, COCH₂C₆F₅, COCH₂OPh, Ph or C₆F₅) affords M$\text{n(C}{}_6\text{H}{}_4\text{NN}$Ph)-(CO)₄, together with a binuclear complex Mn₂(CO)₆(C₁₂H₁₀N₂) in some cases. The metallation reaction is shown to proceed most readily with Mn-(CH₂Ph)(CO)₅; with this reagent, the metallated complexes M$\text{n(C}{}_6\text{H}{}_4\text{CH}{}_2\text{P}$Me₂)-(CO)₃[PMe₂(CH₂Ph)] (two isomers) and M$\text{n(C}{}_6\text{H}{}_4\text{CH}{}_2\text{A}$sMe₂(CO)₄ have been obtained on treatment with EMe₂(CH₂Ph) (E  P and As, respectively).     

Dicyclopentadienyl-η1-cyclooctatrienyltitanium and dicyclopentadienyl-η3-cyclooctatrienylniobium

Dicyclopentadienyl-η¹-cyclooctatrienyltitanium and -η³-cyclooctatrienylniobium are prepared from (C₅H₅)₂MCl₂ (M = Ti, Nb) and two equivalent amounts of i-PrMgCl in the presence of an excess of cyclooctatetraene. For the preparation of (C₅H₅)₂NbC₈H₉ the presence of NaBH₄ is also necessary. The products obtained are characterized by IR, mass and ¹H NMR spectroscopy. Reactions with HCl, thermal decomposition reactions, magnetic measurements and elemental analyses were performed to establish the structures.     

The preparation of di- and tri-phenylstannyl esters of aromatic dithio acids,and some of their reactions

Some crystalline di- and tri-phenylstannyl esters [ArCS₂SnPh₃ and (ArCS₂)₂SnPh₂] of aromatic dithio acids have been prepared in good yields and characterized. Preferential cleavage of the SnS bond of the ester was observed by treating them with primary and secondary amines as well as with phenacylidenetetramethylenesulfurane.     

Trinuclear π-cyclopentadienyl bridging sulphido derivatives of iron

The reaction of [Fe(π-C₅H₅)(CO)₂]₂ with the dialkyl disulphides R₂S₂ (R = CH₃, C₂H₅, t-C₄H₉ or CH₂C₆H₅) affords, as well as dinuclear derivatives of the type [Fe(π-C₅H₅)(CO)SR]₂, trinuclear species of formula [Fe₃(π-C₅H₅)₃(CO)₂(S)SR].     

Sulfur heterocycles. I. Use of 4,4-dimethyl-1,3-oxathiolane-3,3-dioxide as a carbonyl anion equivalent

The title heterocycle is used as a carbonyl anion equivalent in the preparation of aldehydes and α-silyl ketones; the key step is the thermal demasking of the heterocycle by loss of isobutylene and sulfur dioxide.     

NMR study of water reorientation in molybdic acids: MoO3 · 2H2O and yellow MoO3 · H2O

Proton NMR relaxation times (T₂, T₁, T_1?) are reported for powder samples of MoO₃ · 2H₂O and yellow MoO₃ · H₂O in the temperature range 150–325 K and at 20 and 60 MHz. No translation of hydrogen atoms is detected but the spin-lattice relaxation behavior indicates reorientation of H₂O molecules. The waters coordinated to Mo atoms undergo 180° flips (about their C₂ axes) with similar motional parameters in both compounds. The interlayer waters in MoO₃ · 2H₂O undergo 180° flips with different parameters. An assumed Arrhenius-type temperature dependence of correlation times leads to preexponential factors which are “anomalously” low. The possible involvement of temperature-dependent activation barriers is discussed.     

Sulfur heterocycles. II. The hydroxyoxathiolane to acyloin rearrangement

Thermal control of demasking conditions may be used to convert hydroxyoxathiolanes into either α-hydroxyaldehydes or the corresponding ring-expanded acyloins.     

Magnetic susceptibility of ruthenium(III) in tris-ethylenediamine salts. Effect of outer sphere ligands

The paramagnetic susceptibility of Ru(III) in tris-ethylenediamine salts has been measured as a function of temperature. In all cases the iodide salt exhibits a greater susceptibility than the bromide salt. This difference may be attributed to a larger degree of temperature independent paramagnetism in the iodide complex due to the presence of low lying charge transfer states.     

The vibrational spectra and normal coordinate analysis of tetracyclopropyllead

All the fundamental frequencies observed in IR and Raman spectra have been assigned to the normal modes of the molecule (C₃H₅)₄Pb (C₃H₅ = cyclopropyl). The calculated force field is compared to that of (C₃H₅)₂Hg and the Cmetal stretching force constants are discussed along with those of Me₄Pb and Me₂Hg; The similarity of the spectra of cyclopropyllead and cyclopropyl-mercury proves that the vibrations of cyclopropyl structural units are isolated in both molecules.