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The new complexes [W2Cp2(CO)4(μ-L2)] (Cp = η5-C5H5; L2 = Ph2PCH2PPh2 (dppm), Me2PCH2PMe2 (dmpm)) have been prepared from [W2Cp2(CO)4] and the corresponding diphosphine at room temperature. Decarbonylation of the dppm complex in refluxing n-octane gives the triply bonded compound [W2Cp2(CO)2(μ-dppm)] as the major product, along with a small amount of the oxo complex [W2Cp2(μ-CH2PPh2)(O)(μ-PPh2)(CO)], which results from a P−C(sp3) cleavage in the dppm ligand. Both compounds (as their dibenzene and toluene solvates, respectively) have been characterized through single-crystal X-ray studies. The analysis of the dicarbonyl complex, carried out at 200 K, reveals the presence of linear semibridging carbonyls experiencing an incipient dynamic disorder that at higher temperatures might be observed as a fully developed disorder of each carbonyl between its two asymmetric dispositions. The latter is consistent with a structure determination carried out previously on the same compound at 291 K and with its dynamic behavior in solution. This air-sensitive complex adds oxygen readily to give the W(I)−W(V) oxo derivative [W2Cp2(O)2(CO)2(η1-dppm)]. Photochemical decarbonylation of [W2Cp2(CO)4(μ-L2)] proceeds via the hydrido cyclopentadienylidene complexes [W2(μ-η1:η5-C5H4)Cp(μ-H)(CO)3(μ-L2)] to finally give the corresponding dicarbonyls [W2Cp2(CO)2(μ-L2)]. The latter react readily with tBuNC at room temperature or below to give [W2Cp2(μ-η1:η2-CNtBu)(CO)2(μ-L2)], which, when L2 = dppm, isomerizes at room temperature to give [W2(μ-η1:η5-C5H4)Cp(μ-H)(CNtBu)(CO)2(μ-dppm)].

Three types of expandable graphite (EG) differing in particle size and expansion volume, are compared as flame retardant additives to rigid polyurethane foams (RPUFs). In this paper we discuss microstructure, thermal stability, fire behavior, and compression performance. We find that ell size distributions were less homogeneous and cell size was reduced. Furthermore, thermal conductivity increased along with EG loading. Thermogravimetric analysis (TGA) showed that EG only increased residue yield differently. The results indicate that a higher expansion of EG increased the limiting oxygen index (LOI) value, whereas a bigger particle size EG improved the rating of the vertical burning test (UL94). Results from the cone calorimeter test showed that a bigger particle size EG effectively reduced peak of heat release rate (pHRR). Furthermore, a higher expansion, led to a decrease in smoke production (TSP). The combination of both characteristics gives extraordinary results. The physical–mechanical characterization of the EG/RPUF foams revealed that their compression performance decreased slightly, mostly due to the effect of a bigger size EG.

Complexes containing one or two Fmes ligands (Fmes = 2,4,6-tris(trifluoromethyl)phenyl = nonafluoromesityl) either trans or cis are obtained by treating palladium(II) chloro complexes with Li(Fmes):  trans-[PdCl2L2] (L = tetrahydrothiophene (tht), PPh3) lead to trans-[Pd(Fmes)ClL2] (L = tht, PPh3) or trans-[Pd(Fmes)2L2] (L = tht); [PdCl2(L-L)] (L-L = 1,5-cyclooctadiene, 2,2‘-bipyridine) give [Pd(Fmes)Cl(L-L)] (L-L = COD, bipy) or [Pd(Fmes)2(bipy)]. The structures of two complexes containing two Fmes ligands in trans and cis arrangement, trans-[Pd(Fmes)2(tht)2] (2) and [Pd(Fmes)2(bipy)] (6), respectively, have been determined by X-ray diffraction. In spite of the severe steric congestion the complexes are four coordinated. Distortions due to the bulkiness of the ortho substituents and short Pd···F3C-ortho distances are observed. The high degree of steric crowding is also responsible for slow rotation around the Pd−P bonds in the complex trans-[Pd(Fmes)Cl(PPh3)2]. ΔG ⧧ associated with this motion is 12.8 kcal mol-1, one of the highest values reported so far for rotation around M−PPh3 bonds. Complexes 2 and 6 are redox inactive by cyclic voltammetry in the range −1.8 to +1.8 V.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Evaluation of the thermal conductivity and mechanical properties of water blown polyurethane rigid foams reinforced with carbon nanofibers

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