Alice C. Sullivan

Synthesis and chemistry of the bis(trimethylsilyl)amido bis-tetrahydrofuranates of the group 2 metals magnesium, calcium, strontium and barium. X-ray crystal structures of Mg[N(SiMe3)2]2·2THF and related Mn[N(SiMe3)2]2·2THF

Abstract Transamination reactions utilizing the compound mercuric bis(trimethylsilyl)amide, Hg{N(SiMe3)2}2, in tetrahydrofuran (THF), and the metals Na, Mg, Ca, Sr, Ba and Al have been investigated. Thus the THF solvated compounds Na[N(SiMe3)2]·THF and M[N(SiMe3)2]2·2THF, M = Mg, Ca, Sr and Ba (1–4), have been prepared. The X-ray crystal structures of 1 and the related manganese compound Mn[N(SiMe3)2]2·2THF (5) are reported. Interaction of the silylamides, 2–4, with a range of crown ethers apparently proceeded with elimination of silylamine, (Me3Si)2NH, and novel ring opening of the crown ethers, generating species containing a donor alkoxide ligand with a vinyl ether function, presumably, O(CH2CH2O)nCHCH2 (n = 3−5). The silylamides 2–4 were also cleanly converted to the corresponding alkoxides (from 1H NMR data) in reactions with stoichiometric quantities of 3-ethyl-3-pentanol.

Allylic and benzylic oxidation using cobalt(II) alkyl phosphonate modified silica

Abstract The allylic and benzylic oxidation of a range of substrates proceeds in good yield using catalytic quantities of cobalt(II) alkyl phosphonate modified silica and tert-butyl hydroperoxide.

Main group and transition metal compounds with silanediolate [R2SiO2]2− and α,ω-siloxane diolate [O(R2SiO)n]2− ligands

Abstract This review is concerned solely with main-group and transition metal compounds incorporating Dn siloxy fragments of the type: O(R2SiO)n. Various reported routes to these metallasiloxane compounds from a range of ligand sources are discussed. Reactions involving siloxanolate ligand transfer with oligomerisation are featured. General structural and spectroscopic features of the compounds are outlined. A summary of reported chemistry for these metallasiloxane compounds is included. Selected information relating to the synthesis, structure and structural parameters of compounds is provided in tables organised according to periodic groups.

Synthesis and structure of the unusual dimeric lithium derivative of the tetraphenyldisiloxanediolate dianion

Abstract The synthesis and structure of the new compound bis[dipyridinodilithium tetraphenyldisiloxanediolate], [Ph 4 Si 2 O(OLiPy) 2 ] 2 ( 1 ), are described, and a number of unusual features discussed.

Development of a direct three-dimensional biomicrofabrication concept based on electrospraying a custom made siloxane sol.

We demonstrate here the discovery of a unique and direct three-dimensional biomicrofabrication concept possessing the ability to revolutionize the jet-based fabrication arena. Previous work carried out on similar jet-based approaches have been successful in fabricating only vertical wallpillar-structures by the controlled deposition of stacked droplets. However, these advanced jet-techniques have not been able to directly fabricate self-supporting archeslinks (without molds or reaction methods) between adjacent structures (walls or pillars). Our work reported here gives birth to a unique type of jet determined by high intensity electric fields, which is derived from a specially formulated siloxane sol. The sol studied here has been chosen for its attractive properties (such as an excellent cross-linking nature as well as the ability to polymerize via polycondensation on deposition to its biocompatability), which promotes direct forming of biostructures with nanometer (<50 nm) sized droplets in three dimensions. We foresee that this direct three-dimensional biomicrofabrication jet technique coupled with a variety of formulated sols having focused and enhanced functionality will be explored throughout the physical and life sciences.

Novel alkylmetal hydroxides. The crystal and molecular structures of bis(µ-hydroxy)-bis{tris(dimethylphenylsilyl)methylzinc}, [{Me2PhSi)3CZnOH}2] and µ4-oxohexa(µ-hydroxy)tetrakis{tris(trimethylsilyl)methylindium}, [O{(Me3Si)3Cln}4(OH)6]

The compounds [{(Me2PhSi)3CZnOH}2] and [O{(Me3Si)3Cln}4(OH)6] have been shown by X-ray diffraction to have structures based on four-membered M2O2-rings (M = Zn or ln).

Synthesis, photochemistry and X-ray crystal structures of the methyltris[bis(trimethylsilyl)amido] compounds MeTi[N(SiMe3)2]3 and MeZr[N(SiMe3)2]3

Abstract The synthesis and characterization of the compound methyltris[bis(trimethylsilyl)amido]titanium, MeTi[N(SiMe3)2]3 (1), is reported. In the presence of UV radiation or sunlight, 1 decomposed rapidly to the titanium(III) species Ti[N(SiMe3)2]3 (2). The X-ray crystal structures of the compounds MeM[N(SiMe3)2]3, M = Ti and Zr (3), are reported. Compound 3 was stable in sunlight, but the cyclometallated product [(Me3Si)2N]2 ZrN(SiMe 3 )SiMe 2 C H2 (4) was apparently formed (from 1H and 13C NMR data) when solutions of 3 were exposed to a source of UV radiation.

Cyclic cobaltadisiloxane compounds. Crystal structures of a pyridinolithium [bis(cyclosiloxy)cobalt] cobalt chloride and a bis(tetramethylethylenediaminolithium)-bis(cyclosiloxy)cobaltate

Abstract Reaction of CoCl 2 and dilithio tetraphenyldisiloxanediolate Ph 4 Si 2 O(OLi) 2 in tetrahydrofuran (THF) followed by removal of the THF, extraction of the residue with toluene, and treatment of the toluene solution with tetramethylethylenediamine (TMEDA) or pyridine (Py) has given the compounds bis [tetramethylethylenediaminolithium]-μ-[octaphenyltetrasiloxyspiro[5.5]cobalt], [TMEDALi] 2 -μ-[ Co(OSiPh 2 -OSiPh 2 O ) 2 ] and bispyridinolithium-μ-[octaphenyltetrasiloxyspiro[5.5]pyridino-cobalt]-μ-pyridinocobalt chloride, [Py 2 Li]-μ-[ Co(OSiPh 2 OSiPh 2 O ) 2 ]-μ-CoPyCl. Both compounds have been characterized by X-ray crystallography.

Oxidation of alcohols using cerium(IV) alkyl phosphonate modified silica

The oxidation of a range of alcohols to ketones or carboxylic acids proceeds in good yield using catalytic quantities of cerium(IV) phosphonate modified silica and sodium bromate as the re-oxidant.

Formation of ring-expanded products from certain combinations of tetraphenyldisiloxanediolates [(Ph2SiOM′)2O](M′= Li or Na) and group 4 metal chlorides MCl4

Experimental conditions and combinations of reagents have been varied in reactions between [(Ph2SiOM′)2O](M′= Li or Na) and Group 4 metal halides MCl4, with the broad aim of assessing their affects on the formation of ring-expanded products. Lithium-7 NMR spectroscopy was used to monitor the reaction between [(Ph2SiOLi)2O] and MgCl2·2thf in thf (tetrahydrofuran) which gives a ring-expanded product. The reaction between [(Ph2SiONa)2O], prepared in situ from sodium metal and (Ph2SiOH)2O, and TiCl4 in a 3 : 1 molar ratio gave the sodium-bridged compound [Ti{O(SiPh2O)2}3{Na(py)}2]·py, py = pyridine, the first example of a six-membered titanasiloxane ring. Further reaction with LiI gave the lithium-bridged analogue. The analogous reaction with HfCl4 gave the ring-expanded compound [Hf{Ph2Si(OSiPh2O)2}2(py)2]·2C6H5Me, the first examples of eight-membered hafnasiloxane rings. Results of 7Li, 29Si, and 23Na NMR, IR, and single-crystal X-ray diffraction studies are reported.