This study reports the isolation and the structural (X-ray), UV-vis, and NMR characterization of a series of electron-rich Ru(II) acetylide complexes of the formula (η 2 -dppe)(η 5 -C 5 Me 5 )Ru(CtC)-1,4-(C 6 H 4 )X (1a-f; X ) NO 2 , CN, F, H, OMe, NH 2 ) and (η 2 -dppe)(η 5 -C 5 Me 5 )Ru(CtC)-1,3-(C 6 H 4 )F (1c-m), as well as the spectroscopic (near-IR and ESR) in situ characterization of the corresponding elusive Ru(III) radical cations. The spectroscopic data are discussed in connection with DFT computations, and a consistent picture of the electronic structure of these Ru(II) and Ru(III) acetylide complexes is proposed. Notably, the strong reactivity of the Ru(III) radicals evidenced in this contribution constitutes a major difference with the relative stability of the known iron analogues.

The complexes {Cp*(PP)Ru}2(μ-C⋮CC⋮C) (PP = dppm 5a, dppe 5b) have been synthesized from RuCl(PP)Cp* (1a/b) via the corresponding vinylidenes [Ru(CCH2)(PP)Cp*]+ (2a/b), deprotonation (KOBut) to the ethynyls Ru(C⋮CH)(PP)Cp* (3a/b), oxidative coupling ([FeCp2][PF6]) to the bis(vinylidenes) [{Ru(PP)Cp*}2{μ-(CCHCHC)}]2+ (4a/b), and deprotonation [dbu (4a), KOBut (4b)]. Electrochemistry of 5a/b revealed the expected sequence of four 1e redox steps, which occurred at significantly lower E° values than found for the Ru(PPh3)2Cp analogue. Single-crystal X-ray structure determinations are reported for 1a/b, 2a/b, 3a/b, 4a/b, and 5a/b, together with the oxidized products [5b][PF6] n (n = 1, 2). In the monocation [5b][PF6] the Ru−C(1) [1.931(2) Å] and C−C distances [1.248−1.338(3) Å] are intermediate between those found in 5b and the dication [5b]2+. The short Ru−C [1.857(5) Å] and experimentally equal C−C distances [1.269−1.280(6) Å] in [5b][PF6]2 confirm the anticipated dicarbene-cumulene structure for the RuCCCCRu bridge.

The reactions of FeCl(dppe)Cp* and Ru(CtCCtCH)L 2 Cp′ with Na[BPh 4 ] and 1,8diazabicyclo[5.4.0]undec-7-ene (dbu; 2 equiv) in a mixed thf/NEt 3 solvent afford {Cp*(dppe)-Fe}(CtCCtC){Ru(PP)Cp′} (PP ) dppe, Cp′ ) Cp*, 7; PP ) (PPh 3 ) 2 , Cp′ ) Cp, 8). Cyclic voltammetry shows that these mixed Fe/Ru complexes undergo sequential loss of up to three electrons, with the mono-and dioxidized species being isolated following chemical oxidation. Computational (DFT) and spectroscopic (IR, NMR, ESR, Mo ¨ssbauer) studies are consistent with a polarized ground-state structure with oxidation leading to the gradual evolution of cumulenic character in the FeC 4 Ru moiety and a greater degree of orbital mixing between the Fe, C, and Ru centers than found in the related heterometallic complex [{Cp*(dppe)-Fe}(CtCCtC){Re(NO)(PPh 3 )Cp*}] n+ ([6] n+ ). In contrast to the two-electron oxidation products derived from the diiron complex {Cp*(dppe)Fe}(CtCCtC){Fe(dppe)Cp*} (1) and iron/rhenium complex 6, the dications [7] 2+ and [8] 2+ feature a dominant contribution from a singlet ground state. Thus, while 6 behaves in a manner closely related to 1, 7 and 8 are more closely related to {Cp(Ph 3 P) 2 Ru}(CtCCtC){Ru(PPh 3 ) 2 Cp} (2) and {Cp*(dppe)Ru}-(CtCCtC){Ru(dppe)Cp*} (3), clearly demonstrating the pronounced role that choice of metal as well as formal electron count can play in tuning the electronic and magnetic properties of this fascinating class of compound.

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Reactions between HC triple bond CC triple bond CSiMe3 and several ruthenium halide precursors have given the complexes Ru(C triple bond CC triple bond CSiMe3)(L2)Cp'[Cp'= Cp, L = CO (1), PPh3 (2); Cp' = Cp*, L2= dppe (3)]. Proto-desilylation of 2 and 3 have given unsubstituted buta-1,3-diyn-1-yl complexes Ru(C triple bond CC triple bond CH)(L2)Cp'[Cp'= Cp, L = PPh3 (5); Cp'= Cp*, L2 = dppe (6)]. Replacement of H in 5 or 6 with Au(PR3) groups was achieved in reactions with AuCl(PR3) in the presence of KN(SiMe3)2 to give Ru(C triple bond CC triple bond CAu(PR3)](L2)Cp'[Cp' = Cp, L = PPh3, R = Ph (7); Cp' = Cp*, L2= dppe, R = Ph (8), tol (9)]. The asymmetrically end-capped [Cp(Ph3P)2Ru]C triple bond CC triple bond C[Ru(dppe)Cp*] (10) was obtained from Ru(C triple bond CC triple bond CH)(dppe)Cp* and RuCl(PPh3)2Cp. Single-crystal X-ray structural determinations of and are reported, with a comparative determination of the structure of Fe(C triple bond CC triple bond CSiMe3)(dppe)Cp* (4), and those of a fifth polymorph of [Ru(PPh3)2Cp]2(mu-C triple bond CC triple bond C) (12), and [Ru(dppe)Cp]2(mu-C triple bond CC triple bond C) (13).

Iron ore sintering involves the movement of a flame front down a particulate bed, and a series of physico-chemical reactions over a large temperature range. In the literature simple and more sophisticated iron ore sintering models have been reported. In this paper a more comprehensive numerical model which incorporates most of the significant processes and heat transfer modes proposed in earlier models is given. Therefore, sub-models are available to describe the relationship between airflow rate through the bed and flame front speed, the evaporation and condensation of water ahead of the front, the calcination of fluxes nearer to the front, the reactions that occur in the front and cooling of the bed with the departure of the front. Improvements were made to several areas -such as coke combustion, and the melting and solidification processes -to more accurately quantify the phenomena involved. More recent progress in understanding the fundamentals of sintering from BHP Billiton studies have also been incorporated into the model. To date, twelve sinter pot tests have been used for validation studies. Reasonably good agreement was obtained between predicted and measured results -in areas such as bed temperature profiles and waste gas temperature and compositions. Work is continuing to further improve the model, and broaden the validation work to include other bed temperature profile parameters.

In iron ore sintering, granule deformation and compaction can be responsible for significant losses in bed voidage and green bed permeability. In this study, uniaxial compression tests have been used to examine the bed strength of granulated single and binary iron ore sinter mixes. The results show that at low moistures, bed strength is dependent on the granule layer mass to nuclei mass ratio. For binary iron ore sinter mixes, bed strength was found to increase as levels of Channel Iron ore were increased. Permeability-moisture curves for a series of single ore sinter mixes were recorded to examine the key parameters that affect this relationship. The results confirmed that the porosity of the ore pore size distribution and contact angle all affect the shape or width of the curves and the moisture at maximum permeability. The height of the curves is determined by bed voidage and the granule size distribution. This study has demonstrated that provided sufficient water is available during granulation, both Channel Iron and Marra Mamba ores granulate well, forming packed beds with permeability and strength comparable with or higher than those formed from less porous Brockman and Itabirite ores.

This paper discusses simultaneous gravity and vertical gravity gradient measurements obtained with a newly designed recoil-compensated dropping chamber adapted to an FG5 absolute gravimeter. The new dropping chamber incorporates counterweights to compensate recoil effects. It has the same physical length as the standard FG5 dropping chamber but the free-fall distance was increased from 20 cm to 25 cm. The new drive train pulls on the centre of the system to reduce unwanted horizontal velocity and rotation of the free-falling test mass. The test-mass material was chosen to reduce possible magnetic eddy-current damping caused by external magnetic field gradients. External lead masses were used to change the gravity and vertical gravity gradient. The measurements agree well with the theoretical gravity field changes derived from the position of the external weights. The experiment clearly demonstrates the efficacy of using an absolute gravity meter to measure both the gravity and the gravity gradient signals caused by variations in the external gravity field. This technique shows promise for passive gravity-monitoring applications.