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Ignition in low temperature combustion engines is governed by a coupling between low-temperature oxidation kinetics and diffusive transport. Therefore, a detailed understanding of the coupled effects of heat release, low-temperature oxidation chemistry, and molecular transport in cool flames is imperative to the advancement of new combustion concepts. This study provides an understanding of the low temperature cool flame behavior of butane isomers in the counterflow configuration through the addition of ozone. The initiation and extinction limits of butane isomers’ cool flames have been investigated under a variety of strain rates. Results revealed that, with ozone addition, establishment of butane cool diffusion flames was successful at low and moderate strain rates. iso-Butane has lower reactivity than n-butane, as shown by higher fuel mole fractions needed for cool flame initiation and lower extinction strain rate limits. Ozone addition showed a significant influence on the initiation and sustenance of cool diffusion flames; as ozone-less cool diffusion flame of butane isomers could not be established even at high fuel mole fractions. The structure of a stable n-butane cool diffusion flame was qualitatively examined using a time of flight mass spectrometer. Numerical simulations were performed using a detailed chemical kinetic model and molecular transport to simulate the extinction limits of the cool diffusion flames of the tested fuels. The model qualitatively captured experimental trends for both fuels and ozone levels, but over-predicted extinction limits of the flames. Reactions involving low-temperature species predominantly govern extinction limits of cool flames. The simulations were used to understand the effects of methyl branching on the behavior of n-butane and iso-butane cool diffusion flames.

Recent developments in the chemistry of homo- and heterometallic clusters of Iron, Cobalt and Nickel triads substituted with alkynes and related ligands are examined. New synthetic procedures, bonding modes and structural arrangements have been found. The old and recent applications of these clusters are discussed.

The reactions of the complexes Fe3(CO)12, H2FeRu3(CO)13, H2Ru4(CO)13 and CpNiRu3(H)3(CO)9 with 2(diphenylphosphino)ethyl-triethoxysilane give considerable yields of the complexes Fe3(CO)10L2 (1), H2FeRu3(CO)10L2 (2), Ru4(CO)10L3 (3) and CpNiRu3(H)3(CO)7L2 (4) where L = Ph2PCH2CH2Si(OEt)3. The complexes (1–3) have been characterized by analytical and spectroscopic techniques. The structure of (4) has been determined by X-ray analysis. The presence of a phosphine containing the –Si(OEt)3 group has been exploited for grafting complexes (3) and (4) on the mesoporous SBA-15 and the resulting inorganic–organometallic materials have been characterized by means of ICP-MS, FT-IR, DR-UV–vis spectroscopy, XRD and textural analysis.

The complex Co2(CO)6[μ-η2-(H3CC CCH2CH2OH)] (1) with the ligand 3-pentyn-1-ol (pol) has been synthesized following established procedures. Its structure has been determined by X-ray analysis. The complex Co2(CO)6(mbo) (mbo = 2-methyl-3-butyn-2-ol, HC CC(CH3)2OH), (3), along with the already known Co2(CO)6(bud) (bud = 1,4-butyn-diol, HOCH2C CCH2OH) (2), and Co2(CO)8 were reacted with 2(diphenylphosphino)ethyl-triethoxysilane [Ph2PCH2CH2Si(OCH2CH3)3] (dpts) and tris(hydroxymethyl)phosphine [P(CH2OH)3] (thp). With dpts, mono- and di-substituted complexes were obtained: these were characterized by analytical and spectroscopic techniques. The structures of Co2(CO)6(dpts)2 (5) and of Co2(CO)4(pol)(dpts)2 (8) have been determined by X-ray analysis. Complex (1) was reacted with 3-(triethoxysilyl)propyl isocyanate [(H3CCH2O)3Si(CH2)3NCO] (tsi): the new complex Co2(CO)6[H3CC CCH2CH2OC( O)NH(CH2)3Si(OCH2CH3)3] (9) was obtained and spectroscopically characterized. The complex has also been reacted with tetraethyl orthosilicate (teos); a new inorganic–organometallic material was obtained. Complex (5) has been grafted on the mesoporous material SBA-15. The hybrid inorganic–organometallic materials obtained have been characterized by inductively coupled plasma-mass spectrometry (ICP-MS), infrared spectroscopy (FT-IR) under vacuum conditions, X-ray diffraction (XRD) and scanning electron microscopy coupled to EDS probe (SEM–EDS).

The reactions of Fe3(CO)12 with 2-methyl-3-butyn-2-ol and 3-pentyn-1-ol in CH3OH/KOH solution lead, respectively, to the binuclear complex Fe2(CO)6(μ-CO)(μ-η2-[HCC{ C(CH3)2}C( O)(OCH3)]) (as the main product) and to the closed trinuclear hydridic complex (μ-H)Fe3(CO)9(μ3-η3-[H3CCC(CH2)(CH2)CO]) (as the unique product). The oxygenated ligands of these complexes are formed, respectively, by coupling of a formerly coordinated CO with a methoxy group and by coupling of a formerly coordinated CO with a deoxygenated alkynic residual.

The title compound has been obtained in considerable yield by reacting Ru3(CO)12 with 2-pentynal-diethyl-acetal [CH3CH2C CC(H)(OEt)2] (PDA) in hydrocarbon solvents. The X-ray analysis shows that the title complex belongs to the well known family of the flyover derivatives. Some X-ray structural studies have been reported, many years ago, on di-iron flyover complexes; in contrast only a few examples of diruthenium derivatives have been structurally characterized. The complex contains ethoxy-groups which could potentially undergo hydrolysis in the presence of tetraethyl-orthosilicate (TEOS) in the presence of catalysts. Reactions of complex Ru2(CO)6[μ-η4-{EtC2C(H)(OEt)2}CO{EtC2C(H)(OEt)2}] with TEOS in the presence of HCl or of NaF (as catalysts) have been attempted. An inorganic-organometallic sol-gel material containing the skeleton of the complex has been obtained and characterized with IR-Raman, XRD on powders and SEM microscopy.

The reactions of Fe3(CO)12 with but-2-yn-1,4-diol (BUD), 1,4-dichloro-but-2-yne (DCB), propargyl alcohol (PA) and propargyl chloride (PC) in KOH/CH3OH solutions (followed by acidification with HCl) and under thermal conditions have been examined. The complex Fe2(CO)6{H2CCCCH2} is the main product of the reactions with BUD or DCB in all conditions. The complexes Fe2(CO)6{H2CCC(H)C(OMe)O} and Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH3}CCH2} are the main products obtained respectively in the reactions with propargyl chloride (PC) or propargyl alcohol (PA) in basic methanolic solution. The structures of the three complexes have been determined by means of X-ray analysis. Complex Fe2(CO)6{H2CCCCH2} contains a butatrienyl ligand in an uncommon structural arrangement. The formation of complex Fe2(CO)6{H2CCC(H)C(OMe)O} requires CO and methanol activation; its ferrole like structure contains a coordinated acetate group. Complex Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH 3}CCH2} contains one Fe(CO)4 and one Fe2(CO)6 fragments linked through a carbon atom chain derived from the insertion of CO and dimerization of propargyl alcohol (with substitution of OCH3 from methanol in the place of OH). Comments on the syntheses and on the reaction pathways leading to the complexes are made.

The title complex is obtained by reacting Ru3(CO)12 with 1,4-dichloro-but-2-yne (ClCH2C CCH2Cl, DCB) in CH3OH/KOH solution (followed by acidification with HCl). The X-ray structure analysis shows that (μ-H)2Ru3(CO)9{μ3-η2-[H2C C(H)CCC( O)OCH3]} complex contains a “parallel” ene-yne acetyl substituent, H2C C(H)C CC( O)OCH3; the formation of such a ligand starting from DCB is – to our knowledge – unprecedented. The synthesis of complex (μ-H)2Ru3(CO)9{μ3-η2-[H2C C(H)CCC( O)OCH3]} occurs through the activation of CO and methanol. This process has been found for other reactions of functionalized alkynes with M3(CO)12 carbonyls (M = Fe, Ru) under basic methanolic conditions. The known hydridic cluster, (μ-H)Ru3(CO)9[μ3-η3-(MeCCHCH)] has been identified as the minor reaction product.

The reaction of Ru3(CO)12 with but-2-yn-1,4-diol (HOCH2CCCH2OH, BUD) in CH3OH/KOH followed by acidification with HCl leads to four products, one of which has been identified as the title complex (μ-Cl)Ru3(CO)9[μ3-η4-H2CCC(H)CH2]. This is an open cluster containing a bridging Cl atom on the open side and a C4H5 moiety bound to all the metals. The structure of the complex has been determined by X-ray analysis. The thermal reaction of Ru3(CO)12 with BUD has been revisited for a comparison with the results in alkaline solution. The main product is the allylic derivative HRu3(CO)9[HCCHCCHO].

The title complex (μ-H)Ru3(CO)9(μ3-η3-C3H3) has been obtained following two different reaction pathways: one is the deamination of diethylaminopropyne, HCCCH2NEt2, in the presence of Ru3(CO)12 under thermal conditions. The other is the reaction of trimethylsilylpropargyl alcohol, (HO)H2CCC(SiMe3) (TSPA), with Ru3(CO)12. The complex is obtained both under thermal conditions and in the reaction of the carbonyl with TSPA in CH3OH/KOH (followed by acidification). Other reaction products, deriving from the loss of Me3Si and of HCHO fragments from TSPA, have also been characterized. Complex (μ-H)Ru3(CO)9(μ3-η3-C3H3) has been spectroscopically characterized and its crystal structure was determined by an X-ray analysis. An isosceles triangle of Ru atoms with an edge bridged by an H atom, is coordinated by an allylic moiety σ-bonded to two Ru atoms and π-interacting with the third Ru atom.