Two routes for the synthesis of mer-W(CO)(H)(NO)(PMe3)3 (4) are described, starting from mer-W(Cl)(CO)(NO)(PMe3)3 (1) or the borohydride complex mer-W(η 1-BH4)(CO)(NO)(PMe3)3 (3). The propensity of 4 to undergo insertion reactions has been investigated. 4 reacts with benzaldehyde, propionaldehyde, pivalaldehyde, benzophenone, acetophenone, and acetone to afford the corresponding alkoxide complexes mer-W(CO)(NO)(PMe3)3(OCHR‘R‘ ‘) (R‘ = H, R‘ ‘ = Ph (5a); R‘ = H, R‘ ‘ = CH2CH2CH3 (5b); R‘ = H, R‘ ‘ = CH2C(CH3)3 (5c); R‘ = Ph, R‘ ‘ = Ph (5d); R‘ = CH3, R‘ ‘ = Ph (5e); R‘ = CH3, R‘ ‘ = CH3 (5f)). Insertion of CO2 yields the formato-O complex mer-W(CO)(NO)(OCHO)(PMe3)3 (6). Reaction of 4 with CO leads to immediate loss of PMe3 and formation of trans,trans-W(CO)2(H)(NO)(PMe3)2. In a reversible way Fe(CO)5 and Re2(CO)10 insert into the W−H bond of 4, affording the isolable μ-formyl complex mer-W(CO)(NO)(PMe3)3[(μ-OCH)Fe(CO)4] (7a) and mer-W(CO)(NO)(PMe3)3[(μ-OCH)Re2(CO)9] (7b) as an equilibrium constituent. For both reactions equilibrium constants have been derived from VT-NMR measurements and ΔH values were calculated (−46 kJ/mol for 7a and −26 kJ/mol for 7b). An accompanying DFT analysis of the W−H bond demonstrated that a higher number of phosphine ligands in a W(CO)4 - n (H)(NO)(PMe3) n series increases the hydridic character of the H ligand and induces a stronger bond polarization. The relative ΔH values for the insertions of the metal carbonyls with n = 3 could be reproduced. The calculations also suggest that the main difference in the reactivity of Fe(CO)5 and Re2(CO)10 is not primarily an electronic effect but, rather, is due to steric influence. Compounds 3, 4, 6, and 7a were structurally characterized by X-ray diffraction studies.

Group 4 metal complexes containing the di(tert-butyl)cyclopentadienyl ligand (l,3-tBu2-r/5-CsH3) have been synthesized. The reaction of a mixture of 1,3-and 1,4-di(tert-butyl)cyclopentadiene isomers with KH in THF at -78°C gives the salt K+ [(1,]-(THF)I_3 2 as a white solid. Treatment of 2 with chlorotrimethylsilane in a 1:1 molar ratio gives the air-stable trimethylsilylcyclopentadienyl derivative Si(1,3-tBu2C5H3XCH3)3 3. The silyl derivative 3 is an excellent precursor for monocyclopentadienyl trichlorotitanium and zirconium compounds M (28)] as yellow oils which can be stored for weeks under an inert atmosphere. When the same reactions of (14) and (26) with B(C6Fs) 3 are carried out in a 2:1 molar ratio at room temperature, the complexes (29), Hf (30)] can be obtained as a mixture of syn-and anti-isomers as shown by NMR spectroscopic observations. The formation of (29) and (30) implies the stabilization of the 14-electron cationic intermediate by interaction with one methyl group of the neutral complexes (14) and (26). Complexes (27) and (28) undergo heterolytic dissociation of the Metal-MeB(C6Fs) 3 bonds, leading to the formation of the free [M(I,3-tBu2-r/5-CsH3)(r/5-CsHs)(CH3)] + 14-electron species, verified by 1H DNMR spectroscopy. When compound (27) was heated at 50°C the metallacyclic cation [Zr(1-tBu-3-CMezCH2-@-C5H3)(@-CsHs)] + (31) was formed. The alkyl derivatives synthesized and reported herein, activated with * Corresponding author. l X-ray diffraction studies.0022-328X/97/$17.00 © 1997 Elsevier Science S.A. All rights reserved.Pll S0022-3 28X(97)00034-X 156 J.l. Amor et al. / Journal of Organometallic Chemistry 535 (1997) [155][156][157][158][159][160][161][162][163][164][165][166][167][168] MAO, B(C6Fs) 3 or [Ph3C][B(C6Fs)4], polymerize ethylene with very low activity. The molecular structure of [Ti(1,3-tBu2-r/5-C5H3)C1(/x-O)] 3 6 has been determined by X-ray diffraction methods. © 1997 Elsevier Science S.A.

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Background: Micro-texturing is an increasingly used technique that aims at improving the functional behaviour of components during their useful life, and it is applied in different industrial manufacturing processes for different purposes, such as reducing friction on dynamic rubber seals for pneumatic equipment, among others. Micro-texturing is produced on polymer components by transfer from the mould and might critically increase the adhesion and friction between the moulded rubber part with the mould, provoking issues during demoulding, both on the mould itself and on the rubber part. The mould design, the coating release agent applied to the mould surface, and the operational parameters of the moulding/demoulding process, are fundamental aspects to avoid problems and guarantee a correct texture transfer during the demoulding process. Methods: In this work, the lack of knowledge about demoulding processes was addressed with an in-house test rig and a robust experimental procedure to measure demoulding forces (DFs) as well as the final quality of the moulded part, between thermoset polymers and moulds. After the characterization of several Sol-Gel coating formulations (inorganic; hybrid) the influence of several parameters was analysed experimentally, i.e.: Sol-Gel efficiency, texture effects, pattern geometry, roughness and material compound. Results: The results obtained from the experimental studies revealed that texture depth is the most critical geometrical parameter, showing high scatter among the selected compounds. Finally, the experimental results were used to compute a model through reduced order modelling (ROM) technique for the prediction of DFs. Conclusions: The characterization of DFs in a laboratory, with a specific device operated by a universal testing machine (UTM), provided valuable information that allows a fast and optimized introduction of texturing in rubber components. Selection of a novel Sol-Gel coating and the use of the ROM technique contributed to speed up implementation for mass production.

Background: Micro-texturing is an increasingly used technique that aims at improving the functional behaviour of components during their useful life, and it is applied in different industrial manufacturing processes for different purposes, such as reducing friction on dynamic rubber seals for pneumatic equipment, among others. Micro-texturing is produced on polymer components by transfer from the mould and might critically increase the adhesion and friction between the moulded rubber part with the mould, provoking issues during demoulding, both on the mould itself and on the rubber part. The mould design, the coating release agent applied to the mould surface, and the operational parameters of the moulding/demoulding process, are fundamental aspects to avoid problems and guarantee a correct texture transfer during the demoulding process. Methods: In this work, the lack of knowledge about demoulding processes was addressed with an in-house test rig and a robust experimental procedure to measure demoulding forces (DFs) as well as the final quality of the moulded part, between thermoset polymers and moulds. After the characterization of several Sol-Gel coating formulations (inorganic; hybrid) the influence of several parameters was analysed experimentally, i.e.: Sol-Gel efficiency, texture effects, pattern geometry, roughness and material compound. Results: The results obtained from the experimental studies revealed that texture depth is the most critical geometrical parameter, showing high scatter among the selected compounds. Finally, the experimental results were used to compute a model through reduced order modelling (ROM) technique for the prediction of DFs. Conclusions: The characterization of DFs in a laboratory, with a specific device operated by a universal testing machine (UTM), provided valuable information that allows a fast and optimized introduction of texturing in rubber components. Selection of a novel Sol-Gel coating and the use of the ROM technique contributed to speed up implementation for mass production.