An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Combining two different redox-active organometallic moieties, we prepared the compounds [(Cym)-RuCl(dpf)](PF6), with Cym = p-cymene = 1-isopropyl-4-methylbenzene, and the diphosphinoferrocenes (dpf) 1,1'-bis(diphenylphosphino)ferrocene (dppf; complex 3), 1,1'-bis(diisopropylphosphino)ferrocene (dippf; complex 4), and 1,1'-bis(diethylphosphino)ferrocene (depf; complex 5) as well as the structurally characterized hydride complex [(C5Me5)RuH(dippf)] (2). In contrast to the case for 2, with an approximately staggered ferrocene conformation, the chloride complexes 3-5 exhibit a syn-periplanar ferrocene arrangement, due to a Cl center dot center dot center dot H(C5H4) interaction in the solid and in solution. The related new compounds [(Cym)RuH(dppf)](PF6) (6) and trinuclear (mu-dpf)[(Cym)RuCl2)](2) (7-9) were also obtained and identified by H-1 and P-31 NMR spectroscopy. The redox behavior of 2-6 and of the known [(C5Me5)RuH(dppf)] (1) was investigated using cyclic voltammetry, spectroelectrochemistry in the UV/vis/near-IR and ER regions, and, in part, by EPR. The first oxidation of the areneruthenium compounds 3-6 occurs reversibly at the ferrocene site, while the reduction proceeds via an ECE two-electron pattern under chloride dissociation. These results are compared to those obtained for the pentamethylcyclopentadienide/hydride complexes 1 and 2, which demonstrate unambiguously the ruthenium center as the site of the first electron loss. The different results for the two kinds of heterodimetallic d(5)/d(6) mixed-valent intermediates, (FeRuIII)-Ru-II for 1(+) and 2(+) and Fe-III Ru-II for 3(+) -6(+), are discussed with respect to the possible uses of such heterodinuclear systems in H-2 conversion catalysis.

Combining bifunctional phenylenediisocyanates O=C=N-(C6H4=C=O, C6H4 = m- or p-phenylene, with the electron-rich 8 π-electron heterocycle 1, 4-bis(tri-methylsilyl)-1, 4-dihydropyrazine 1 yielded products involving the insertion of both isocyanate finctions into the nitrogen-organosilicon bonds. The crystal structure of the 1:2 bis(insertion) product with m-phenylenediisocyanate is reported, revealing N-silylation and formation of urea functions.

Oxidative coupling of 2-aminopyrimidine with LiOCl produces 5-chloro-2,2′-azobis(pyrimidine) and 2,2′-azobis(5-chloropyrimidine) (abcp), both of which were structurally characterized. The symmetrical abcp was used as strongly π-accepting mono- and bis-chelate ligand in complexes with [(bpy)2Ru]2+, [(H6C6)ClRu]+, [(Ph3P)2Cu]+ and (OC)3ClRe. The π-acceptor capability of abcp results in low-energy MLCT transitions and facile reduction to isolable radical complexes of which the DFT-calculated and structurally characterized dicopper(I) species {(μ-abcp)[Cu(PPh3)2]2}(PF6) was studied by X- and W-band EPR and the complex {(μ-abcp)[Ru(bpy)2]2}(PF6)3 at 9.6, 230 and 285 GHz EPR frequency. The results indicate considerable metal–ligand orbital mixing in the singly occupied molecular orbitals.

The new complexes (RN=CH-CH=NR)Co(NO)(CO), R = isopropyl (1), 2,6-diisopropylphenyl (2) and p-tolyl (3), were synthesized and spectroscopically characterized. Compounds I and 2 could be crystallized for X-ray structure analysis, CO/NO disorder was observed for 1. The results indicate a negligible amount of charge transfer from the Co(NO)(CO) moiety to the 1,4-diaza-butadiene acceptor ligands in the ground state, in agreement with DFT calculations on I and as similarly reported for related 1,4-diaza-1,3-butadiene complexes of Ni(CO)(2) and Fe(NO)(2).

The compounds [(Cym)OsCl(dxpf)](PF6), Cym=p-cymene and dxpf: 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,1′-bis(diethylphosphino)ferrocene (depf) or 1,1′-bis(diisopropylphosphino)ferrocene (dippf), were synthesized and characterized by NMR (1H, 31P) and, in the case of [(Cym)OsCl(dppf)](PF6), by X-ray structure analysis of the acetonitrile solvate. EPR and UV–vis spectroelectrochemistry indicate the formation of an osmium(II)–ferrocenium species on reversible one-electron oxidation. The second oxidation and the reduction are electrochemically irreversible.

The four complexes [MCl(C5Me5)(N∧S)](PF6), M=Rh, Ir; N∧S=1-methyl-2-(methylthiomethyl)-1H-benzimidazole (mmb) and 1-methyl-2-(tert-butylthiomethyl)-1H-benzimidazole (mtb) were synthesized and characterized by spectroscopy, electrochemistry and X-ray crystallography (as methanol solvates). The essential coordination features, viz., longer M–S (ca. 2.38 Å) and shorter M–N bonds (ca. 2.09 Å) in five-membered chelate rings are common to all four species. Cyclic voltammetry reveals irreversible two-electron reduction to MI complexes and partially reversible oxidation to IrIV species for [IrCl(C5Me5)(mtb)]+. The results are discussed in comparison with those obtained for α-diimine (N∧N) complexes of the [MCl(C5Me5)]+ fragments.

Oxidation of [Cp*RuH(dppf)] (1), dppf=1,1′-bis(diphenylphosphino)ferrocene, and [(Cym)RuCl(dppf)](PF6) (2), Cym=p-cymene, occurs at ruthenium for 1 but yields a ferrocenium species for compound 2.

Reaction of OsCl3 with pentamethylcyclopentadiene in ethanol in air yields the ionic osmium(IV) compound [Cp*2OsCl](2)[OsCl6] which has been identified structurally and by vibrational spectroscopy. Under comparable conditions the RuCl3 homologue yields the ruthenium(III) compound [Cp*RuCl2](2), illustrating the more facile oxidation of the 5d element to the tetravalent state.

Neutral complexes (PPh3)2Cu(L) were obtained from (PPh3)2Cu(NO3) and the deprotonated forms of the three Schiff base ligands 2-(benzylideneimino)phenol (BimOH), 4-(benzylideneimino)resorcinol (Bim(OH)2) and N-(2,4-dihydroxy-5-isopropylphenyl)acetamide (DipaH3). The ligands were designed to model aminated intermediate forms of the topaquinone (TPQ) cofactor in the enzymatic cycle of copper-dependent amine oxidases. The ligands L are coordinated to the metal centers through imine-N and phenolate-O donor atoms to form five-membered chelate rings, in contrast to the six-membered chelate rings of salen-type Schiff base ligands. Compound (Bim(OH)O)Cu(PPh3)2·0.5CH3OH was structurally analyzed, it exhibits intramolecular aryl–aryl interactions between the ligands and intermolecular hydrogen bonds involving the free phenolic hydroxyl substituent, the coordinated phenolate oxygen atom and the methanol solvate molecule.

Reaction of 1,2-phenylenediamine with 2-pyridinecarboxaldehyde gave the new compound 1-(2-pyridylmethyl)-2-(2-pyridyl)benzimidazole (L) which reacted with [Cu(CH3CN)4](BF4) to form the title complex. Although the imine/2-(2-pyridyl) (‘α-diimine’) coordination setting in L appears well suited for forming a five-membered chelate ring, the crystal structure analysis of the bis(methanol) solvate revealed that the system rather opts for the formation of a partially saturated eight-membered chelate ring involving both pyridyl groups with a twist angle of 61.8° between the benzimidazole and 2-(2-pyridyl) moieties. In addition, L acts as a tridentate ligand, effecting dimerization of two chelate rings through the imine nitrogen centers of the imidazole groups. This dimerization gives rise to a ten-membered dimetalla ring. Tetracoordination at copper(I) is complemented by acetonitrile. The preference for this structure is attributed to the formation of unstrained metal centers with N–Cu–N angles between 105° and 118° and Cu–N distances of 2.03–2.05 Å.

Qualitatively similar metal coordination as in PQQ-dependent bacterial dehydrogenases was observed for the PQQ triester in the model complex I, although the unusual five-coordinate copper(I) center is smaller and softer than the Ca2+ ion of the native enzymes. The ambidentate PQQ thus prefers coordination through the O(5)/N(6)/O(7') atoms even without additional support from the protein scaffold.

Complexes of 2,5-bis(1-phenyliminoethyl)pyrazine (bpip), a symmetrical bis(bidentate) ligand which acts through two different chelate donor centres, one imine and one azine nitrogen atom per metal chelate site, have readily been obtained with Cr(CO)(4), Mo(CO)(4), W(CO)(4), Mn(CO)(3)Cl, Re(CO)(3)Cl, [Ru(bpy)(2)](2+) and [Cu(PPh3)(2)](+) fragments. The 'free' ligand and the dinuclear [{Cu(PPh3)(2)}(2)(mu-bpip)][BF4](2) were characterised crystallographically. The low-energy molecular conformation of free bpip is qualitatively different from the planar syn/trans/syn arrangement required in the bpip-bridged dicopper(I) compound (Cu ... Cu distance 6.944 Angstrom). Structural preferences and the pi acceptor properties of the conjugated bridging ligand bpip were studied using DFT calculations of the bpip(0/-/2-) chromophore and combined electrochemical and spectroscopic methods; bpip is a stranger pi acceptor than the related 2,5-bis(2-pyridyl)pyrazine but a poorer mediator of metal-metal interaction.

Not only Au-I and Hg-II species but also Cu-I(SR) fragments can bind in a highly dissymmetrical fashion to symmetrical diimine chelate ligands; the 2 + 1 coordination arrangement observed for the metal in two complexes (tmphen)Cu(SR) (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline) is characterised by obtuse angles alpha[N(1)-Cu-S] > 159 degrees and by two very different distances Cu-N(1) and Cu-N(2).

Double chelate coordination of [Cu(Ph3 P)2 ]+ stabilizes the radical anion of 2,2'-azobis(5-chloropyrimidine), which exhibits a N-N bond length of 1.345(7) Å in the complex (see picture). This is consistent with a one-electron reduced azo functionality.

Stabilisiert durch zweifache Chelatkoordination von {Cu(Ph3P)2}+ ist das Radikalanion von 2,2′-Azobis(5-chlorpyrimidin), das im Komplex (siehe Bild) eine N-N-Bindungslänge von 1.345(7) Å aufweist – in Übereinstimmung mit einer einfach reduzierten Azofunktion.