Showing papers by "Georgina M. Rosair published in 1998"

Metalation of a Bis(thiophenyl)carborane Giving Both Exo and Endo Products. Synthesis and Structural Characterization of RuCl{7,8-(SPh)2-7,8-nido-C2B9H10}(p-cymene) and 1,2-(SPh)2-3-(p-cymene)-3,1,2-RuC2B9H9†

Abstract: Reaction of [7,8-(SPh)2-7,8-nido-C2B9H10]- with [RuCl2(p-cymene)]2 affords RuCl{7,8-(SPh)2-7,8-nido-C2B9H10}(p-cymene). Deprotonation of the carborane then treatment with the same reagent affords 1...

1‐[Chloro(diphenylphosphino)gold(I)‐P]‐2‐phenyl‐1,2‐dicarba‐closo‐dodecaborane(12)

Abstract: The title compound, 1-[(C6H5)2PAuCl]-2-(C6H5)-1,2-closo-C2B10H10 or [AuCl{(C6H5)2P(C8H15B10)}] is the first reported derivative of 1-[(C6H5)2P]-2-(C6H5)-1,2-closo-C2B10H10. The conformation of the cage phenyl group is comparable with the parent carbaborylphosphine, however the (C6H5)2PAuCl substituent is less tilted from an idealized radial position on C1 due to a balance between two opposing sets of intramolecular forces. The P—Au—Cl fragment adopts the expected linear geometry.

Synthesis and characterisation of derivatives of monocyclopentadienylbis(arene-1,2-dithiolato)titanium(IV); crystal structures of M[Ti(η5-C5Me5)(1,2-S2C6H4)2] [M = Tl or N(PPh3)2]

Abstract: Thallium(I) derivatives of monocyclopentadienylbis(arene-1,2-dithiolato)titanium, Tl[Ti(η5-C5HnMe5 – n)(S2C6H3R)2 (1–6; n = 0, 4 or 5; R = H or Me), have been synthesised and isolated in yields of 31–65% from reactions of the corresponding trichloromonocyclopentadienyltitanium reagents, Ti(η5-C5HnMe5 – n)Cl3 and thallium salts of the benzene-1,2-dithiol or toluene-3,4-dithiol in tetrahydrofuran. Reaction between Tl[Ti(η5-C5Me5)(1,2-S2C6H4)2] and bis(triphenylphosphine)iminium chloride, [N(PPh3)2]Cl, has also afforded the derivative [N(PPh3)2][Ti(η5-C5Me5)(1,2-S2C6H4)2] 7. Products have been characterised by elemental analysis, NMR, IR and mass spectroscopy, and by X-ray diffraction. The structure of 7, in the crystalline state as a tris(dichloromethane) solvate, comprises an ionic lattice containing discrete [Ti(η5-C5Me5)(1,2-S2C6H4)2]– anions of four-legged piano stool geometry with two chelating benzene-1,2-dithiolate ligands folded along the S· · ·S axis in exo and endo conformations, respectively, relative to the cyclopentadienyl ring. The crystal structure of Tl[Ti(η5-C5Me5)(S2C6H4)2] 1 contains two forms of the anion [Ti(η5-C5Me5)(S2C6H4)2]– in endo/endo and endo/exo conformations, respectively, which are unsymmetrically co-ordinated to the TlI cations. A TlI ion is connected by two Tl–S bonds to endo dithiolate ligands of each anion and there is also one Tl–S interaction between pairs of endo/endo and endo/exo forms. Additional weaker Tl· · ·S interactions to the TlI ions generate a linked chain of dimeric units. In solution, NMR spectra suggest a more symmetrical structure for all derivatives but shifts in resonances support the retention of co-ordinate links between the cyclopentadienylbis(arene-1,2-dithiolato)titanium anion and TlI.

Synthesis and characterisation of monocyclopentadienyl dithiolato complexes of niobium and tantalum; crystal structures of [Nb2(µ-O)(µ-η2∶η2-S2C2H4)(η5-C5H4Me)2Cl4] and [Nb2(µ-η1∶η2-S2C2H4)2(η5-C5H4Me)2O(S2C2H4)]†

Abstract: Reactions of tetrachloro(cyclopentadienyl)niobium with arenedithiolates yielded products [NbCp(1,2-S2C6H3R-4)2] (Cp = η5-C5H5; R = H 1 or Me 2), characterised primarily by analysis, 1H NMR and mass spectroscopy. Cyclic voltammetric studies on 1 and 2 showed two consecutive, quasi-reversible, reduction processes; ESR spectra of the initial products of chemical reduction were typical of those from niobium(IV) species with an unpaired electron largely centred on the metal and assigned to the anions [NbCp(1,2-S2C6H3R-4)2]–. Similar tantalum derivatives were less tractable, although properties of the more soluble species [TaCp′(1,2-S2C6H4)2] (Cp′ = η5-C5H4Me) are reported. Reactions of tetrachloro(methylcyclopentadienyl)-niobium or -tantalum with salts of ethane-1,2-dithiol (H2edt) were very susceptible to hydrolysis and the major isolable products of reactions using the sodium reagent (Na2edt) were [M2(µ-O)(µ-η2∶η2-edt)Cp′2Cl4] (M = Nb 4 or Ta 5), containing oxo and symmetrical dithiolate bridges. Reaction of [NbCp′Cl4] with 2 molar equivalents of Tl2edt formed the unsymmetrical compound [Nb2(µ-η1∶η2-edt)2Cp′2O(edt)] 6, containing a terminal oxide ligand, one chelating and two unsymmetrically bridging edt groups. Structures of compounds 4 and 6 have been determined in the solid state by X-ray crystallography; 1- and 2-D NMR spectra of the binuclear products support the retention of these structures in solution.

3‐(η3‐Allyl)‐3,3‐dicarbonyl‐4‐(dimethyl sulfido)‐3,1,2‐molybdadicarba‐closo‐dodecaborane(12)

Abstract: The title charge-compensated allyl carbamolybdaborane 3-(η3-C3H5)-3,3-(CO)2-4-SMe2-3,1,2-closo-MoC2B9H10 has been synthesized and its solid-state structure determined. In the solid state the conformation of the {Mo(η3-C3H5)(CO)2} fragment is such that the carbonyl ligands are approximately trans to the cage C atoms and the conformation of the allyl group is exo.