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The salt elimination reactions of [NEt4][Mo(CSe)(CO)2(Tp*)] ([NEt4][2], Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with a range of metal halide complexes (ClMLn) have been investigated as a possible route to isoselenocarbonyl complexes [Mo(CSeMLn)(CO)2(Tp*)]. Thus the reactions of [NEt4][2] with [RuCl(L)2(η-C5R5)] provide molybdenum-ruthenium derivatives [Mo{CSeRu(L)2(η-C5R5)}(CO)2(Tp*)] (L = PPh3, R = H 4, L = CO, R = Me 5), both of which were structurally characterised. The molybdenum-iron derivative [Mo{CSeFe(CO)2(η-C5H5)}(CO)2(Tp*)] (6) was obtained from [NEt4][2] and [FeCl(CO)2(η-C5H5)] however its formulation currently rests on spectroscopic and microanalytical data. The reaction of [NEt4][2] with [RuH(NCMe)(CO)2(PPh3)2]PF6 affords the structurally characterised hydrido-isoselenocarbonyl complex [Mo{CSeRuH(CO)2(PPh3)2}(CO)2(Tp*)] (7) with no indication of coupling of the hydride and selenocarbonyl ligand.

The reaction of HB(NCH2PPh2)2C6H4-1,2 with [OsCl(Ph)(CO)(PPh3)2] affords the boryl pincer complex [OsCl(CO)(PPh3){B(NCH2PPh2)2C6H4}]. This complex, and its ruthenium analogue were observed to undergo various reactions involving substitution of the chloride and triphenylphosphine co-ligands to give new complexes [MCl(CO)(CNC6H2Me3){B(NCH2PPh2)2C6H4}] (M = Ru, Os), [MH(CO)(PPh3){B(NCH2PPh2)2C6H4}] (M = Ru, Os) and [Ru(κ2-S,S′-S2CNEt2)(CO){B(NCH2PPh2)2C6H4}]. The ruthenium complex [RuH(CO)(PPh3){B(NCH2PPh2)2C6H4}] was found to react with carbon disulfide and carbon monoxide to give the complexes [Ru(κ2-S,S′-S2CH)(CO){B(NCH2PPh2)2C6H4}] and [RuH(CO)2{B(NCH2PPh2)2C6H4}], respectively, the latter as an apparently interconverting mixture of cis and trans dicarbonyl isomers.

The reactions of N,N'-bis(phosphinomethyl)dihydroperimidine pro-ligands H2C(NCH2PR2)2C10H6-1,8 (R = Ph 1a, R = Cy 1b) with iridium(i) substrates have been investigated and shown to readily result in chelate-assisted C-H activation processes. The reaction of 1b with [Ir2Cl2(COE)4] (COE = cyclo-octene) affords the 18-electron iridium(iii) dihydrido complex [IrH2Cl{κ3-C,P,P'-C(NCH2PCy2)2C10H6}], which forms [IrHCl2{κ3-C,P,P'-C(NCH2PCy2)2C10H6}] under acidic (HCl) conditions. In contrast, reaction of 1a with [Ir2Cl2(COD)2] (COD = 1,5-cyclo-octadiene) affords the complex [IrCl(COD){κ2-P,P'-H2C(NCH2PPh2)2C10H6}], thermolysis of which affords cyclo-octene and the pincer-NHC complex [IrCl{κ3-C,P,P'-C(NCH2PPh2)2C10H6}]. The reaction of 1a with two equivalents of [Ir2Cl2(COD)2] provides the binuclear complex [Ir2{μ-H2C(NCH2PPh2)2C10H6}Cl2(COD)2] which is also observed to accumulate and then dissipate during the preceding thermolysis. Related binuclear complexes [M2{μ-H2C(NCH2PPh2)2C10H6}Cl4(η-C5Me5)2] (M = Ir, Rh) which obviate C-H activation were similarly synthesised.

Alum-treated wooden artefacts from the Oseberg collection display a great deal of morphological, structural and compositional inhomogeneity. Thus, an in-depth understanding of chemical processes underlying their degradation requires consideration of a variety of local environments. In addition to alum, sources of inorganic compounds include metal parts, corrosion products of which can migrate into the surrounding wood. In order to characterise the inorganic compounds a range of local environments, samples from several locations in a selection of composite objects have been investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDS). We have found that corrosion of iron rods used in reconstruction has formed iron(II) sulfates, which have migrated into the alum-treated wood to form sulfates containing combinations of potassium, aluminium, iron(II) and iron(III) cations. Reactions of alum were also evident from the presence of alunite in some samples. Areas with significant abundances of zinc sulfates, zinc sulfide and elemental sulfur were also detected. These results provide a first-time window into the complex array of inorganic species that can be present in such composite alum-treated objects.

The reaction of N,N′-bis(dicyclohexylphosphinomethyl)dihydroperimidine (H2C(NCH2PCy2)2C10H6-1,8, 1a) with [RuCl2(PPh3)3] in THF affords the perimidinylidene-based N-heterocyclic carbene (per-NHC) pincer complex [RuCl2(OC4H8){═C(NCH2PCy2)2C10H6}] (2) via chelate-assisted double C–H activation. In contrast, the reactions of the tetraphenyl analogue H2C(NCH2PPh2)2C10H6 (1b) with [RuCl2(PPh3)3] and of 1a with [RuCl(R)(CO)(PPh3)2] (R = Ph, CH═CHPh) do not result in C–H activation but rather give the asymmetric, PNP-coordinated complexes [RuCl2(PPh3){κ3P,N,P′-CH2(NCH2PPh2)2C10H6}] (3) and [RuCl(R)(CO){κ3P,N,P′-CH2(NCH2PCy2)2C10H6}] (R = Ph (4), CH═CHPh (5)), respectively, in which the ruthenium migrates rapidly between nitrogen donors. This provides insight into the mechanistic pathway by which the proligands 1 undergo per-NHC formation, as demonstrated by the thermal conversion of 4 to [RuHCl(CO){═C(NCH2PCy2)2C10H6}] (6) and benzene.

The reaction of HB(NCH2PPh2)2C6H4-1,2 with [MCl2(PPh3)3] (M = Ru, Os) affords the six-coordinate σ-borane complexes [MCl2(PPh3){σ-BH-κ2-P,P′-HB(NCH2PPh2)2-C6H4}], in which the B–H bond remains intact while coordinated to the metal center. Replacement of the unique phosphine by π-acceptor ligands, e.g., CO and CNC6H2Me3, induces B–H activation followed by spontaneous dehydrochlorination with the formation of the boryl pincer complexes [RuCl(CA)2{B(NCH2PPh2)2C6H4}] (A = O, NC6H2Me3-2,4,6).

The reactions of 1,8-diaminonaphthalene with paraformaldehyde and secondary phosphines (HPR2, R = Ph, Cy) directly afford N,N′-bis(phoshinomethyl)dihydroperimidines H2C(NCH2PR2)2C10H6 (R = Ph (1a), Cy (1b)), the methylene group of which undergoes chelate-assisted double C–H activation with [RhCl(PPh3)3] to afford dihydroperimidine-derived N-heterocyclic pincer carbene (per-NHC) complexes [RhCl{═C(NCH2PR2)2C10H6}] (R = Ph (2a), Cy (2b)). Insight into the mechanism of these C–H activation processes is provided by the reaction of 1b with [IrCl(CO)(PPh3)2] to provide the dihydroperimidinyl-hydrido complex [IrHCl(CO){CH(NCH2PR2)2C10H6}] (3b), which in turn reacts with silver salts Ag[Y] to afford, via hydride abstraction and subsequent C–H activation, the per-NHC ligated salts [IrHCl(CO){═C(NCH2PR2)2C10H6}] ([4b]Y, Y = PF6, SbF6, PO2F2).

The reaction of [Et4N][Mo(CSe)(CO)2(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with [Rh2(μ-Cl)2(η4-cod)2] (cod = cyclo-octa-1,5-diene) results in the formation of the tetrametallic com...

The successive treatment of terminal alkynes, HC≡CR (R = C6H4Me-4, SiMe3), with nBuLi and gray selenium affords LiSeC≡CR, which in turn reacts with [FeCl(CO)2(η-C5H5)], [NiCl(PPh3)(η-C5H5)], and [M...

The reactions of N,N'-bis(phosphinomethyl)dihydroperimidine pro-ligands H2C(NCH2PR2)2C10H6 (R = Cy 1a, R = Ph 1b) with [RuCl2(PPh3)3] give markedly different products. Chelate-assisted double C-H activation in the former affords the perimidinylidene-based N-heterocyclic carbene (per-NHC) pincer complex [RuCl2(OC4H8){κ(3)-P,C,P'-C(NCH2PCy2)2C10H6}] (2), while the latter reaction provides the asymmetric PNP-coordinated complex [RuCl2(PPh3){κ(3)-P,N,P'-CH2(NCH2PPh2)2C10H6}] (3), in which no C-H activation has occurred. Subsequent reactions of the per-NHC complex 2 with carbon monoxide and mesityl isocyanide readily displaced the labile THF ligand to afford the complexes [RuCl2(CA){κ(3)-P,C,P'-C(NCH2PCy2)2C10H6}] (A = O 4, A = NC6H2Me35). Double C-H activation of 1a and 1b was significantly more facile on reaction with [OsCl2(PPh3)3], providing the per-NHC complexes [OsHCl(PPh3){κ(3)-P,C,P'-C(NCH2PR2)2C10H6}] (R = Cy 7a, R = Ph 7b, respectively), each as two isomers. The reactions of 1b with [Ru2(μ-Cl)2Cl2(η-C6H3Me3)2] or [AuCl(THT)] (THT = tetrahydrothiophene) provide the bimetallic complexes [Ru2{μ-H2C(NCH2PPh2)2C10H6}Cl4(η-C6H3Me3)2] (8) and [Au2{μ-H2C(NCH2PPh2)2C10H6}Cl2] (9) without C-H activation occurring.

The reaction of [Et4N][Mo(CSe)(CO)2(Tp*)}] (Tp* = hydrotris(dimethylpyrazolyl)borate) with [Ir(NCMe)(CO)(PPh3)2]BF4 results not in the anticipated isoselenocarbonyl complex [(Tp*)(CO)2Mo−CSe−Ir(CO)...