Bis(acetato-κO)bis­(pyridine-2-aldoxime-κ2 N,N′)nickel(II)

In the mononuclear title compound, [Ni(CH3COO)2(C6H6N2O)2], the NiII atom is coordinated by two pyridine-2-aldoxime (PaoH) ligands and two acetate groups, with cis coordination for the pairs of identical ligands. While each acetate group binds to the NiII atom by one O atom, each PaoH chelates the NiII atom through two N atoms. The O atom on PaoH is not deprotonated and does not participate in bonding to the NiII atom. Thus, the NiII atom exhibits an octa­hedral environment. Intra­molecular O—H⋯O hydrogen-bonding inter­actions and inter­molecular C—H⋯O hydrogen-bonding inter­actions are present in the structure. Adjacent mol­ecules pack along [100] through van der Waals forces

[1,2-Bis(diphenyl­phosphan­yl)ethane-2κ2 P,P′]tetra­carbonyl-1κ3 C,2κC-(μ-2-cyclo­pentyl-2-aza­propane-1,3-dithiol­ato-1:2κ4 S,S′:S,S′)diiron(II)(Fe—Fe)

In the title compound, [Fe2(C7H13NS2)(C26H24P2)(CO)4], the Fe2S2 core exhibits a butterfly-like shape, with two S atoms bridging the Fe–Fe dumbbell. Each of the two Fe atoms exhibits a distorted octa­hedral environment. One Fe atom is additionally bonded to three carbonyl C atoms, whereas the other Fe atom is additionally bonded to one carbonyl C atom and two P atoms of the chelating dppe [dppe = 1,2-bis­(diphenyl­phosphan­yl)ethane] ligand. Non-classical intra­molecular C—H⋯S hydrogen-bonding inter­actions are present in the structure. The packing of adjacent mol­ecules along [100] is accomplished mainly through van der Waals forces

Bis(acetyl­acetonato)oxido(triphenyl­phosphine oxide)vanadium(IV)

In the structure of the title compound, [V(C5H7O2)2O(C18H15OP)], the V atom adopts a slightly distorted octa­hedral geometry with its coordination completed by four O atoms of two acetyl­acetonate (acac) ligands, one oxo group and one O atom of the triphenyl­phosphine oxide (OPPh3) ligand

A triclinic polymorph of bis­(μ2-ethane­thiol­ato)-1:2κ2 S:S;3:4κ2 S:S-(μ4-disulfido-1:2:3:4κ4 S:S:S′:S′)tetra­kis­[tricarbonyl­iron(II)](2 Fe—Fe)

Next to the monoclinic polymorph [Cheng et al. (2005 ▶). Acta Cryst. E61, m892–m894], the triclinic title compound, [Fe4(C2H5S)2(S2)(CO)12], is the second known form of this composition. The structure is composed of an [Fe2(C2H5S)(S)(CO)6] subcluster, which is linked to its counterpart by an inversion centre located at the mid-point of the central disulfide bond. The Fe2S2 core of each subcluster exhibits a butterfly-like shape, with two S atoms bridging two Fe atoms. In the subcluster, each Fe atom is coordinated in a distorted octa­hedral coordination by three terminal carbonyl C atoms, two S atoms and one Fe atom. The crystal packing is accomplished through van der Waals inter­actions

Contribution of the vertical movement of dissolved organic carbon to carbon allocation in two distinct soil types under Castanopsis fargesii Franch. and C. carlesii (Hemsl.) Hayata forests

International audienceAbstractKey messageThe vertical transport of dissolved organic carbon (DOC) is an important determinant of carbon distribution across a soil profile. The transport of DOC down a soil profile can be largely influenced by incoming DOC and soil organic carbon (SOC) levels, which insulate DOC from adsorption processes regulated by soil texture and Fe/Al mineralogy.ContextUncertainties about how soil properties affect DOC transport through the soil profile require study because soils can differ strongly with respect to texture or Fe/Al mineralogy and yet retain similar quantities of DOC.AimsThis study aimed to assess the role of incoming DOC and native SOC in regulating DOC migration in soils and investigate the contribution of DOC movement to SOC allocation.MethodsWe leached a standard DOC solution extracted from Castanopsis carlesii litter through two distinct soil types, using two leaching strategies: single leaching and sequential leaching. The two soil types under a natural Castanopsis carlesii (Hemsl.) Hayata forest and a natural Castanopsis fargesii Franch. forest, respectively, differ strongly with respect to soil texture, Fe/Al oxide abundances, and SOC nature.ResultsWith single leaching, where each of six soil layers making up an entire 0–100-cm soil depth profile received single doses of standard DOC solution, deeper soil layers retained more DOC than upper soil layers, with native SOC largely masking the effects of soil texture and Fe/Al mineralogy on DOC migration. Following sequential leaching, where a sixfold larger amount of standard DOC solution sequentially percolated through the six soil layers, the upper soil layers generally retained more DOC than deeper layers. Nevertheless, in sequential leaching, desorption-induced transfer of carbon from upper soil layers to deeper soil layers resulted in greater total carbon retention than in single leaching.ConclusionForest subsoils (40–100 cm) are well below C saturation, but DOC vertical movement from top soils only transfers limited organic carbon to them. However, DOC vertical movement may greatly alter SOC allocation along the top soil profile (0–40 cm), with part of outer sphere native SOC displaced by incoming DOC and migrating downwards, which is a natural way to preserve SOC

Non-innocent bma ligand in a dissymetrically disubstituted diiron dithiolate related to the active site of the [FeFe] hydrogenases

International audienceThe purpose of the present study was to evaluate the use of a non-innocent ligand as a surrogate of the anchored [4Fe4S] cubane in a synthetic mimic of the [FeFe] hydrogenase active site. Reaction of 2,3-bis(diphenylphosphino) maleic anhydride (bma) with [Fe2(CO)6(µ-pdt)] (propanedithiolate, pdt = S(CH2)3 S) in the presence of Me3NO-2H2O afforded the monosubstituted derivative [Fe2(CO)5(Me2NCH2PPh2)(µ-pdt)] (1). This results from the decomposition of the bma ligand and the apparent C–H bond cleavage in the released trimethylamine. Reaction under photolytic conditions afforded [Fe2(CO)4(bma)(µ-pdt)] (2). Compounds 1 and 2 were characterized by IR, NMR and X-ray diffraction. Voltammetric study indicated that the primary reduction of 2 is centered on the bma ligand