Can litter production and litter decomposition improve soil properties in the rubber plantations of different ages in Côte d’Ivoire?

Litter production and litter decomposition influence the availability of nutrients in the soil. The investigation aimed at characterizing the dynamics of leaf litter decomposition, and soil physico-chemical and biological parameters in rubber plantations of different ages. During a 12-months’ period, field studies were done in 7-, 12-, and 25-year-old rubber plantations. For measuring of litter decomposition and input from aboveground, 324 litter bags and 27 litter traps (1 m?×?1 m) were placed in 3 sampling areas per age class of rubber plantations. The soil parameters were also characterized. The results showed that the annual litter production and the amounts of organic carbon in leaves increased with the aging of the plantations. The annual decomposition constant (k) ranged from 0.0381?±?0.0040 year^?1 in the 25-year-old plantations to 0.0767?±?0.0111 year^?1 in the 7-year-old plantations. The annually decomposed litter mass varied between 2.7?±?0.3 t ha^?1 year^?1 in the 12-year-old plantations to 4.2?±?0.3 t ha^?1 year^?1 in the 25-year-old plantations. The soil of the 25-year-old plantations showed higher values of most physico-chemical and biological variables as compared to the 7-year-old plantations: annual litter production (+?32%), annual litter mass decomposed (+?11%), annual carbon (+?15%) and nitrogen (+?11%) inputs, soil organic carbon (+?52%), total nitrogen (+?32%), soil organic matter (+?52%), soil water content (+?74%), and the total density of soil invertebrates (+?121%). The results indicate an improvement of soil properties with the aging of the rubber plantations and the importance of this agricultural system for carbon sequestration.     

Oxidation of cobalt(II) to cobalt(III) in the presence of phosphorus and sulphur donors via –O–C bond cleavage: synthesis and structure of [CoIII(dppe)(EtOCS2)(COS2)] (dppe=1,2-bis(diphenyl phosphino)ethane)

An ethanolic solution of cobalt(II) reacts with dppe (1,2-bis(diphenyl phosphino)ethane) and etxant (ethyl xanthate) affording an intensely coloured Co^III complex, [Co^III(dppe)(etxant)(COS₂)], by eliminating [EtOC(S)(SEt)] via –O–C bond rupture. The structure of the cobalt(III) complex has been confirmed by X-ray crystallography, NMR and mass spectrometry.     

The formation of [RuCl(p-cymene)(Me2HPz)(PPh2OR)]Cl (Me2HPz=3, 5-dimethylpyrazole; R=H,Me and p-Tol) complexes from the cleavage of the P–N bond of a P-coordinated P(Me2Pz)Ph2 ligand by ROH molecules in a ruthenium(II) complex. Crystal structure of [RuCl(p-cymene)(Me2HPz)(PPh2OH)]Cl

The complex [RuCl₂(p-cymene)]₂ reacts with 1-(3,5-dimethyl)pyrazolyldiphenylphosphine (P(Me₂Pz)Ph₂) to give the complex RuCl₂(p-cymene)(P(Me₂Pz)Ph₂). This compound reacts with ROH molecules (R=H, Me and p-Tol) to give [RuCl(p-cymene)(Me₂HPz)(PPh₂OR)]Cl (R=H, Me and p-Tol) complexes, which contain both Me₂HPz and PPh₂OR coordinated molecules.     

Two intra-molecular inter-ligand C(aromatic)–H⋯O(carboxyl) interactions reinforce the formation of a single Cu(II)–N4(pza) bond in the molecular recognition between pyrazine-2-carboxamide (pza) and the (iminodiacetato)copper(II) chelate. Synthesis,molecular and crystal structure and properties of [Cu(IDA)(pza)(H2O)]·H2O

Aqua(pyrazine-2-carboxamide)(iminodiacetato)copper(II) monohydrate, [Cu(IDA)(pza)(H₂O)]·H₂O, was synthesised and characterised by thermal, spectral, magnetic and X-ray diffraction methods. Its crystal structure was solved to a final R1=0.058. The Cu(II) atom exhibits a square base pyramidal coordination (type 4+1) with IDA ligand in mer-tridentate configuration [Cu–N(aliphatic) 1.986(7), Cu–O(carboxyl) 1.933(6) and 1.938(5) Å], the Cu–N4(pza) bond [1.984(7) Å] and Cu–O(apical aqua) bond [2.347(8) Å]. The N4-monodentate ligand role of pza is in contrast with that of the N,O-bidentate pza-Cu(II) chelation in [Cu(pza)₂(ClO₄)₂] or [Cu(acac)(pza)(ClO₄)]·H₂O. In the molecular recognition between Cu(IDA) chelate and pza the Cu–N4(pyridine-like) coordination mode is preferred because it enables the additional contribution of two weak intra-molecular inter-ligand C(aromatic)–H⋯O (IDA) interactions.