Search

Ferrocenyl diphosphine bridged diiron dithiolate complexes have been prepared and their redox properties investigated by CV and IR SEC supported by DFT calculations to give insight into their proton reduction and hydrogen oxidation activity.

Air and moisture stable diaryl dithiocarbamate salts, Ar2NCS2Li, result from addition of CS2 to Ar2NLi. They react cleanly to afford [Co(S2CNAr2)3] which decompose in amine solutions to give CoS2.

The reaction between differently substituted borasiloxanes and 2,5-bis(3-pyridylethynyl)thiophene provided the first example of luminescent borasiloxane-based chiral helices held together by N-B bonds. The starting building blocks and the helices were fully characterized, and the nature of the N-B bond rationalized by means of theoretical calculations.

[GeCl2(dioxane)] reacts with the neutral aza-macrocyclic ligands L, L = Me3tacn (1,4,7-trimethyl-1,4,7-triazacyclononane), Me4cyclen (1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) or Me4cyclam (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) and two mol. equiv. of Me3SiO3SCF3 in thf solution to yield the unusual and hydrolytically very sensitive [Ge(L)][O3SCF3]2 as white solids in moderate yield. Using shorter reaction times [Ge(Me3tacn)]Cl2 and [Ge(Me3tacn)]Cl[O3SCF3] were also isolated; the preparation of [Ge(Me4cyclen)][GeCl3]2 is also described. The structures of the Me3tacn complexes show κ(3)-coordination of the macrocycle, with the anions interacting only weakly to produce very distorted five- or six-coordination at germanium. In contrast, the structure of [Ge(Me4cyclen)][O3SCF3]2 shows no anion interactions, and a distorted square planar geometry at germanium from coordination to the tetra-aza macrocycle. Crystal structures of the Si(iv) complexes, [SiCl3(Me3tacn)]Y (Y = O3SCF3, BAr(F); [B{3,5-(CF3)2C6H3}4]) and [SiHCl2(Me3tacn)][BAr(F)], obtained from reaction of SiCl4 or SiHCl3 with Me3tacn, followed by addition of either Me3SiO3SCF3 or Na[BAr(F)], contain distorted octahedral cations, with facialκ(3)-coordinated Me3tacn. The open-chain triamine, Me2NCH2CH2N(Me)CH2CH2NMe2 (pmdta), forms [SiCl3(pmdta)][BAr(F)] and [SiBr3(pmdta)][BAr(F)] under similar conditions, containing mer-octahedral cations.

Five titanium arsine compounds have been synthesised via the reaction of TiCl(4) with AsPh(3) (1 : 1 and 1 : 2 equivalents), or one equivalent of Ph(2)AsCH(2)AsPh(2), (t)BuAsH(2) and As(NMe(2))(3). In general, 1 : 1 and 1 : 2 adducts of the type [TiCl(4)(L)(n)] (n = 1, L = AsPh(3), Ph(2)AsCH(2)AsPh(2), and (t)BuAsH(2); n = 2, L = AsPh(3)), were isolated and characterised. However, the reaction of TiCl(4) with As(NMe(2))(3) resulted in a novel exchange between a Cl and an NMe(2) group, yielding the product [TiCl(3)(NMe(2))(mu-NMe(2))(2)AsCl]. The crystal structure of [TiCl(3)(NMe(2))(mu-NMe(2))(2)AsCl] has been determined and showed that the titanium and arsenic atoms are linked via two bridging NMe(2) groups. Additionally, crystal structures for the 1 : 1 and 1 : 2 adducts, [TiCl(4)(AsPh(3))] and [TiCl(4)(AsPh(3))(2)] have been obtained, with Ti-As bond lengths of 2.7465(13) and 2.7238(7) A observed respectively. The decomposition of the compounds has been investigated using thermogravimetric analysis, aerosol-assisted and low pressure chemical vapour deposition.

Reactions of Fe(C-N-C)(N2)2, 1a, or Fe(C-NMe-C)(N2)2, 1b, C-N-C = 2,6-bis(arylimidazol-2-ylidene)pyridine, C-NMe-C = 2,6-bis(arylimidazol-2-ylidene)-3,5-dimethylpyridine, aryl = 2,6-iPr2C6H3, with silanes are described. Complex 1a with excess SiPhH3 and complex 1b with excess Si(tol)H3, Ph = phenyl, C6H5, tol = 2-methylphenyl, gave the complexes [Fe(C-N-C)(SiH2Ph)2(η2-H-SiH2Ph)], 2a, and [Fe(C-NMe-C)(SiH2tol)2(η2-H-SiH2tol)], 2b, respectively. Complex 1b with excess SiPhH3 gave [Fe(C-NMe-C)(SiH2Ph)2(H)2], 3, which was formulated as a dihydride based on the relaxation time T1(min) in the 1H-NMR spectra. Reaction of 1a with SiPh2H2 gave complex [Fe(C-N-C)(SiHPh2)2(η2-H2)], 4, while reaction with Si(mes)H3 gave complex [Fe(C-N-C)(SiH2mes)2(N2)], 5, mes = mesityl, 2,4,6-trimethylphenyl. The comparison of the reactivity with other ‘pincer’ complexes of iron and the mechanism leading to 2a–5 are discussed.

The reaction of NiBr2(DME), DME = 1,2-dimethoxyethane, with the ‘pincer’ pyridine dicarbene ligands (C-N-C) (2) and (C-NMe-C) (2Me), (C-N-C = 2,6-bis-[(DiPP)imidazol-2-ylidene]pyridine, C-NMe-C = 2,6-bis-[(DiPP)imidazol-2-ylidene]-3,5-dimethylpyridine, DiPP = 2,6-diisopropylphenyl) gave the square planar complexes [Ni(C-N(Me)-C)Br]Br, 3·(Br)− and 3MeMe·(Br)− respectively. Transmetallation from [(C-NMe-C)2Ag2](Ag6I8), 6MeMe·(Ag6I8)2− to NiBr2(DME) gave [Ni(C-NMe-C)Br](AgI2), 3MeMe·(AgI2)−. Reaction of 3·(Br)− with KPF6 resulted only in exchange of the ionic bromide, however the reaction of 3·(Br)− with AgBF4 in MeCN or AgOTf in THF resulted in the exchange of both coordinated and ionic bromides, giving rise to the square planar 4·(BF4)−2 and octahedral 5, respectively. In contrast, the reaction of 3MeMe·(AgI2)−, with excess AgOTf resulted in an unusual ‘reverse transmetallation’ leading to 6MeMe·(OTf)−. The substitution of tmeda in Ni(CH3)2(tmeda), tmeda = N,N,N′,N′-tetramethylethylenediamine, by 2 produced the complex 7, in which ring opening of the heterocyclic imidazole ring of one of the NHC functional groups has taken place.