Kinetics of wetting of a compacted powder by aqueous solutions of surface active agents

Summary The capillary rise of aqueous solutions of anionic wetting agents into a compacted powder of an organic chromium complex is discussed on the basis of the Washburn-Rideal equation expanded to account for the porous structure parameters.At the porosity 1 —/6, corresponding to the loosest packing of monodisperse spheres the penetration rate is found to be mostly governed by the effective tensions operative at the moving three phase line of contact in case no deflocculation intervenes.

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Zusammenfassung Der Kapillaraufstieg wässeriger Lösungen anionischer Netzmittel in gepreßtem Pulver eines organischen Chrom-Komplexes wird durch die erweiterte Gleichung vonWashburn-Rideal wiedergegeben, in der die Parameter der porösen Struktur mit einbezogen werden.Bei der Porosität 1 —/6, die der lockersten Anordnung gleichförmiger Kugeln entspricht, wird die Eindringgeschwindigkeit meistens durch die an der sich bewegenden Dreiphasengrenze wirkenden Grenzflächenspannungen bestimmt, wenn keine Peptisation eintritt.

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Paper presented at the XII Intern. Congr. Fat Research, Milan, September 1974.     

Chelating diphos ligands with inorganic backbones. Crystal structure of [PtCl2{(PPh2O)2SiPh2}]

The metallo-phosphaalkenes (η⁵-C₅Me₅)(CO)₂FeP=C(R)(SiMe₃) (Ia: R = SiMe₃, Ib: R = Ph) and MeO₂C---CC---CO₂Me undergo a dipolar [3+2]-cycloaddition to afford the metallo-heterocycles [(η⁵-C₅Me₅)(CO)

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=C(R)SiMe₃] (IIIa,b) with exocyclic P=C double bonds.     

The μ3-cyclopentadienylidene ligand: X-ray structure of [Ru4(CO)5 {P(OMe)3}(μ3-C5H4)2(η-C5H5)2]

UV irradiation of [Ru₂(CO)₄(η-C₅H₅)₂] yields the tri- and tetra-ruthenium complexes [Ru₂(CO)₄(η-C₅H₅){η-C₅H₄Ru(CO)₂(η-C₅H₅)}] and [Ru₄(CO)₆(μ₃-C₅H₄)₂(η-C₅H₅)₂]. The μ₃-C₅H₄ ligand in the latter has been characterised through an X-ray diffraction study on [Ru₄(CO)₅{P(OMe)₃}(μ₃-C₅H₄)₂(η-C₅H₅)₂].     

2,2′-Bis((di-tert-butylphosphino)methyl)-1,1′-biphenyl (ditbi): a bulky analogue of bisbi. The crystal structure of [Rh2Cl2(1,5-cod)2(μ-ditbi)]

Diphosphine 2,2′-bis(di-tert-butylphosphino)methyl)-1,1′-biphenyl (ditbi) is synthesised by the addition of to 2,2′-bis(bromomethyl)-1,1′-biphenyl, followed by deprotection with diethylamine. Treatment of [Rh₂Cl₂(1,5-cod)₂], with ditbi gives [Rh₂Cl₂(1,5-cod)₂(μ-ditbi)] (2) as confirmed by its X-ray crystal structure determination. Hydroformylation of 1-hexene using [Rh(acac)(CO)₂]/ditbi as catalyst gave n- and iso-heptanal in a ratio of 1:1.     

Neutron diffraction structure analysis of [(μ-H)(μ-NCHCF3)Os3(CO)10] at 20 K

The characterisation of (μ-H)(μ-NCHCF₃)Os₃(CO)₁₀ by neutron single crystal structure analysis at 20 K is reported. The 1,1,1-trifluoroethylidenimido ligand derived from the reaction of trifluoroacetonitrile with H₂Os₃(CO)₁₀ bonds as a three-electron donor, symmetrically bridging the same edge of the Os₃ cluster as the μ-hydride ligand.     

Chloro­bis­(tri­phenyl­phosphine)­nickel(I)

Crystals of the title compound, [NiCl(C₁₈H₁₅P)₂], contain one mol­ecule per asymmetric unit with no short intermolecular interactions. This is noteworthy since previous studies have reported that the formally 15‐electron species oligomerizes in the solid state. The nickel(I) centre has a distorted trigonal–planar coordination geometry, the origin of which is suggested to be electronic in nature.     

Mechanochemistry: opportunities for new and cleaner synthesis

The aim of this critical review is to provide a broad but digestible overview of mechanochemical synthesis, i.e. reactions conducted by grinding solid reactants together with no or minimal solvent. Although mechanochemistry has historically been a sideline approach to synthesis it may soon move into the mainstream because it is increasingly apparent that it can be practical, and even advantageous, and because of the opportunities it provides for developing more sustainable methods. Concentrating on recent advances, this article covers industrial aspects, inorganic materials, organic synthesis, cocrystallisation, pharmaceutical aspects, metal complexes (including metal-organic frameworks), supramolecular aspects and characterization methods. The historical development, mechanistic aspects, limitations and opportunities are also discussed (314 references).     

Chiral palladium bis(phosphite)PCP-pincer complexes via ligand C-H activation

The synthesis of a range of chiral palladium bis(phosphite) pincer complexes has been achieved via C-H activation of the parent ligands and one of the complexes formed shows good activity in the catalytic allylation of aldehydes.     

Synthesis and reactivity of cobalt boryl complexes

The reaction between [Co(PMe3)4] and B2(4-Mecat)2 (4-Mecat = 1,2-O2-4-MeC6H3) or between [Co(PMe2Ph)4] and B2(cat)2 (cat = 1,2-O2C6H4) affords the paramagnetic Co(II) bisboryl complexes [Co(PMe3)3[B(4-Mecat)]2] and [Co(PMe2Ph)3{B(cat)]2] respectively, both of which have been structurally characterised. ESR data and preliminary diboration and boryl transfer reactivity studies are also presented. The reaction between [CoMe(PMe3)4] and B2(cat)2 affords the Co(I) monoboryl complex [Co(PMe3)4[B(cat)]].