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tert-Butylthiophosphinidene complex [tBuSP-W(CO)5 ] was generated by dissociation of 1-(tert-butylthio)phosphirane-W(CO)5 complex under mild conditions. The formation of transient [tBuSP-W(CO)5 ] was indicated by trapping reactions with 2,3-dimethyl-1,3-butadiene, alkynes, phenanthrene-9,10-dione, and methanol. The LUMO of [MeSP-W(CO)5 ] is significantly lower in energy than those of [Me2 NP-W(CO)5 ], [MeOP-W(CO)5 ], and [Me2 PP-W(CO)5 ]. The HOMO of [MeSP-W(CO)5 ] contains a significant contribution from the in-plane lone pair of P and the LUMO shows a typical π* characteristic. Since stabilized by sulfur lone pair and coordinated by W(CO)5 , [tBuSP-W(CO)5 ] undergoes facile and reversible cycloadditions with alkenes and alkynes.

Seasonal snow cover in mountainous regions will affect local climate and hydrology. In this study, we assessed the role of altitude in determining the relative importance of temperature and precipitation in snow cover variability in the Central Tianshan Mountains. The results show that: (a) in the study area, temperature has a greater influence on snow cover than precipitation during most of the time period studied and in most altitudes. (b) In the high elevation area, there is a threshold altitude of 3,900 ± 400 m, below which temperature is negatively correlated whereas precipitation is positively correlated to snow cover, and above which the situation is the opposite. Besides, this threshold altitude decreases from snow accumulated period to snow stable period and then increases from snowmelt period to snow-free period. (c) Below 2,000 m, there is another threshold altitude of 1,400 ± 100 m during the snow stable period, below (above) which precipitation (temperature) is the main driver of snow cover. (Less)

Spatial and temporal patterns of trends in annual and seasonal precipitation over Germany during 1951–2013 were analysed using the ensemble empirical mode decomposition (EEMD) method. Three widely used and recognized high-resolution observation-based gridded precipitation products, the Climatic Research Unit (CRU) time-series data, Global Precipitation Climatology Centre (GPCC) Full Data Reanalysis data and the EU-FP6 project ENSEMBLES derived data set (EOBS), were used and compared. Comparison among different products showed that the CRU used a considerably lower number of gauge stations (maximum 36) in the construction of gridded product over Germany and should be used with great caution for other applications, and overall CRU presented less precipitation and smaller inter-annual variability; GPCC and EOBS agreed well in the spatial and temporal distribution of seasonal and annual precipitation, as well as the identified trends. The spatiotemporal analysis of trends showed that trends in precipitation during 1951–2013 were, in most cases, highly nonlinear and varying over time. In particular, the spring, summer and autumn precipitation showed large variations in trends. Therefore, the assumption of linear trends on which previous studies were based is invalid. Annual precipitation showed increasing trends in over 66% of Germany (particularly northern and eastern Germany), and the magnitude of increasing trends were generally enhanced over time, e.g. GPCC showed that the average magnitude of increasing trends rose from 6.3% for the 1951–1980 period to 12% for the 1951–2013 period. There were considerable spatial and temporal variabilities in trends in seasonal precipitation totals over Germany. This study is among one of the first studies applying the EEMD method to a comprehensive analysis of time-varying trends in precipitation over Germany, which is expected to improve our understanding of the complex and nonlinear regional climate system. (Less)

Projected increases in temporal precipitation variability, including intra-annual and interannual variability, will likely have important impacts on terrestrial ecosystem productivity. The direction and magnitude of these impacts and how they vary across biomes, however, remain largely uncertain. Here, we review published literature that investigated the effect of different characteristics of temporal precipitation variability on vegetation productivity. We first reviewed commonly used methods, including manipulation experiments, process-based modeling, and data-driven analysis, and further discussed their strengths and limitations. Then, we summarized state-of-the-art research on this topic by categorizing the results based on the characteristics of temporal precipitation variability. Given the same amount of growing season precipitation, a more extreme precipitation regime, characterized as fewer but larger precipitation events, tends to have a negative impact on vegetation productivity of most ecosystems except xeric grasslands and wet-cold forests. Precipitation in the early growing season was found to be particularly important to vegetation productivity. Greater interannual precipitation variability tends to decrease vegetation productivity, but the reported patterns are complex, as both concave-up and concave-down precipitation-productivity relations were found. Despite the progress made so far, critical challenges and knowledge gaps remain, such as the global-scale impacts across different biomes, the role of biological adaption, and the contribution of individual precipitation events. Future research needs to combine manipulation experiments across a broad spectrum of ecosystem types and environmental gradients with model-data integration strategies to disentangle the interactions between abiotic and biotic factors controlling vegetation responses to precipitation variability. This article is categorized under: Science of Water > Hydrological Processes Water and Life > Nature of Freshwater Ecosystems. (Less)

The wide occurrence of carbon-phosphorus bond activation in modern organic synthesis, catalyst deactivation, and biological process has attracted interest for synthetic applications. Over the past few decades, transition-metal-mediated transformations have become extremely powerful tools in organic synthesis. In this review, considerable progress that has been made in catalytic activations and transformations of carbon-phosphorus bonds within the coordination sphere of transition metals is described. Mechanistic information is also presented, and it is hoped that this review not only provides an account of the state of the art in the field, but also highlights the future potential of these reactions in organic synthesis.

A 1-phosphaacenaphthylene has been obtained by the deprotonation and collapse of the phosphorus bridge of an appropriate 7-phosphanorbornenium salt. DFT computations showed that the molecule has an elongated P=C double bond of 1.736 A with a strained C–P=C angle of 88.9°. The P lone pair corresponds to the HOMO–2. Its complexation by [W(CO)5] or AuCl induced a clean addition of methanol and water to the P=C double bond. The water addition product was characterized by X-ray crystal structure analysis.

International audience; Monometallic gold(I)-alkynyl-helicene complexes (1a,b,) and bimetallic gold(I)-alkynyl-helicene architectures featuring the presence (2a,b) or absence (3a,b) of aurophillic intramolecular interactions were prepared by using different types of phosphole ligands (mono-phosphole L1 or bis-phospholes L2,3). The influence of the Au(I) d10-metal center(s) on the electronic, photophysical and chiroptical properties of these unprecedented phosphole-gold(I)-alkynyl-helicene complexes were examined. Experimental and theoretical results highlight the importance of ligand-to-ligand-type charge transfers and the strong effect of presence or absence of Au(I)-Au(I) interactions in 2a,b.

Samples of typical street dust were collected from Jiansheng Town, Chongqing City and classified into four groups on the basis of particle size: 0–75, 75–150, 150–300, and 300–1000 μm. The pollutant content and heavy metal composition of the samples were investigated. The particles in the 0–75, 75–150, 150–300, and 300–1000 μm groups had mass fractions of 20.82% ± 8.86%, 24.68% ± 9%, 30.83% ± 9.76%, and 23.68% ± 15.56%, respectively. The highest concentration of nutritional pollutants was detected in the 300–1,000 µm group, with total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) concentrations of 3.07 ± 2.48, 0.64 ± 0.39, and 83.79 ± 65.28 g/kg, respectively. The lowest concentration of nutritional pollutants was observed in the 150–300 μm group, with TN, TP, and TOC concentrations of 1.78 ± 1.22, 0.51 ± 0.20, and 36.74 ± 24.64 g/kg, respectively. The nutritional pollutants presented similar mass fractions in the street dust samples with different particle sizes. Vegetation significantly affected the TOC content in the samples. The TOC content of the streets with rich vegetation was 1.90 ± 0.56 times that of the streets with less vegetation. The 150–300 µm group had the highest heavy metal mass percentage. Among the heavy metals detected in street dust, Cd, Cr, and Ni were mainly residuals; Cu and Pb were oxidizable; and Zn was mainly acid-extractable. © 2015 American Institute of Chemical Engineers Environ Prog, 2015

Electrophilic terminal phosphinidene complexes [Ar-Ar-P-W(CO)5 ] (Ar-Ar: biaryl or an analogue thereof) undergo a spontaneous insertion of the phosphorus atom into the vicinal CH bonds to give annelated phospholes. Twelve examples are described, including biphenyl, thienyl, pyrrolyl, and benzofuryl groups as biaryl moieties. The activation energy of the insertion reaction is quite low (about 2 kcal mol(-1) ).

Combining compliant electrode arrays in open-mesh constructs with hydrogels yields a class of soft actuator, capable of complex, programmable changes in shape. The results include materials strategies, integration approaches, and mechanical/thermal analysis of heater meshes embedded in thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) hydrogels with forms ranging from 2D sheets to 3D hemispherical shells.

Benzophospholes are obtained by intramolecular cyclization reactions of phosphinophenylalkynes involving a C—P bond cleavage and arylphosphination of the CC bond using a Pd(OAc)2/CuI bimetallic catalyst system.

International audience; new angle: The insertion of a 2,2′-biphosphole subunit into π-conjugated systems offers a new way to control the HOMO-LUMO gap. Tuning of the dihedral angle (θ) between the two phosphorous heterocycles, either by metal coordination or covalent bonding through the P substitution can lead to control of the band gap. These new π-conjugated systems can be used as emitting materials in white organic light-emitting devices (WOLEDs).

The reaction of tributylphosphane with a 7-(2′-formyl-2-biphenylyl)phosphanorbornadiene P-W(CO)5 complex leads to the 5-phosphaphenanthrene P-W(CO)5 complex via an intramolecular phospha-Wittig condensation. This complex is stable enough for detection by 31P NMR spectroscopy but cannot be isolated due to its high reactivity. It is trapped by addition of MeOH or cycloaddition with 2,3-dimethylbutadiene or a nitrileimine. The adducts were characterized by X-ray crystal structure analysis.

In this paper, a model using the energy approach was established to investigate the formation of fish-eye shape in the gigacycle fatigue failure. The model was used to predict the size of the fish-eye formed by a given subsurface inclusion. The predicted results were comparable with the fractography of SNCM439 steel and other experimental results of gigacycle fatigue available in the literature. The current model can capture the fish-eye shape and can be used to predict the life of crack initiation during fatigue failure.

The C factor, representing the impact of plant and ground cover on soil loss, is one of the important factors of the Modified Universal Soil Loss Equation (MUSLE) in the Soil and Water Assessment Tool (SWAT) to model sediment yield. The daily update of C factors in SWAT was originally determined by land use types and plant growth cycles. This does not reflect the spatial variation of C values that exists within a large land use area. We present a new approach to integrate remotely sensed C factors into SWAT for highlighting the effect of detailed vegetative cover data on soil erosion and sediment yield. First, the C factor was estimated using the abundance of ground components extracted from remote sensing images. Then, the gridding data of the C factor were aggregated to hydrological response units (HRUs), instead of to land use units of SWAT. In the end, the C factor values in HRUs were integrated into SWAT to predict sediment yield by modifying the ysed subroutine. This substitution work not only increases the spatial variation of the C factor in SWAT, but also makes it possible to utilize other sources of C databases rather than those from the United States. The demonstration in the Dage basin shows that the modified SWAT produces reasonable results in water flow simulation and sediment yield prediction using remotely sensed C values. The Nash–Sutcliffe efficiency coefficient (ENS) and R2 for surface runoff range from 0·69 to 0·77 and 0·73 to 0·87, respectively. The coefficients ENS and R2 for sediment yield were generally above 0·70 and 0·60, respectively. The soil erosion risk map based on sediment yield prediction at the HRU level illustrates instructive details on spatial distribution of soil loss. Copyright © 2011 John Wiley & Sons, Ltd.

A DFT study suggests that the conversion of arsolylcarbenes into arsenines as described by Markl proceeds via arsabenzvalenes. A similar conversion does not work with phospholylcarbenes. However, we have found that, in some cases, 1-diazoalkylphosphole sulfides are converted into phosphinine sulfides whose in situ reduction by triphenylphosphite affords the dicoordinate phosphinines.

Correcting an earlier report, the reaction of 1-phenyl-3,4-dimethylphosphole (1a) with an excess amount of dimethyl acetylenedicarboxylate (DMAD) at room temperature affords the stable cyclopentadienylidenephosphorane 3a resulting from unexpected deoxygenation of initially formed [phosphole + 2DMAD] adduct 2a by the starting phosphole. The identity of 3a was established by X-ray crystal structure analysis. DFT calculations on a model [1+2] adduct similar to 2a shows a bent allenic structure and an ambident reactivity for the terminal carbon of the (DMAD) 2 chain. Cyclopentadienylidenephosphorane 3b is also obtained with 1-benzyl-phosphole 1b. With 1-stannylphosphole 1c, a 1:3 adduct with a seven-membered ring (i.e., 5) is obtained. It was also characterized by X-ray crystal structure analysis. Finally, with 1-benzyl-2-benzoylphosphole 1d, the P lone pair has lost its nucleophilicity and a [4+2] cycloaddition takes place with the dienol tautomer of the unsaturated ketone to give phosphindole 6, also characterized by X-ray.

Phospholes react with aldimines at 170 °C in the presence of mild Lewis acids to give C2-bridged biphospholes in good yields. The mechanism includes a series of [1,5] shifts of the P-substituents around the phosphole ring, a P–H + aldimine condensation, and the formation of a transient three-membered ring that dimerizes.

The first general synthesis of phospholides and annelated phospholides starting from open-chain precursors is presented.

A novel four-step route towards phosphinines involves the cycloaddition of corresponding phospholes with diverse alkynes, followed by oxidation and oxygen—sulfur exchange at the phosphorus.

The palladium-catalyzed reaction of 2-arylthiophenes (I) with alkynes (II) leads selectively to adducts (III) in moderate yields, whilst the reaction with thiophenes (IV) bearing a 2,6-dimethylphenyl or mesityl moiety proceeds via an other pathway affording products (V).

Silacycles play a very important role in modern organic chemistry and materials science. Construction of silacyclic skeletons via metal-mediated or catalyzed Si-C bond cleavage has attracted much recent attention. Several interesting and useful synthetic strategies have been reported in the literature. In this review, we have summarized recent developments on metal-mediated or catalyzed Si-C bond cleavage, which lead to the synthesis of silacycles, including silacyclobutenes, silacyclopentanes, silacyclopentadienes (siloles), 6-membered silacycles, and their derivatives.

The reaction of benzothiophenes and thiophenes with symmetrical diarylacetylenes leads to the cleavage of C—Br and C—S bonds and C—H activation in one pot.

A simple and efficient palladium-catalyzed three-component domino reaction of bromothiophenes with internal alkynes has been developed to produce benzo[b]thiophenes in moderate to good yields.

A novel four-step route towards phosphinines involves the cycloaddition of corresponding phospholes with diverse alkynes, followed by oxidation and oxygen—sulfur exchange at the phosphorus.

Reaction of zirconacyclopentadienes with 2-iodobenzyl halide and 2-iodobenzoyl halide afforded benzocycloheptene derivatives and benzocycloheptenone derivatives in good to high yields.

Zirconaindenes reacted with allyl halides in the presence of ZnX2 ( X= Cl or Br) and a catalytic amount of Pd(PPh3)4 to give naphthalene derivatives in good yield.

Using 1-R-3,4-dimethylphosphole-N-phenylmaleimide cycloadducts as synthetic equivalents of phosphinidenes [R–P], the following sequence has been developed: [R–P] + R1X → RR1PX → RR1P–OR2.

A practical and efficient method was developed for the synthesis of propargylamines in a one-pot procedure from aldehydes, amines, and alkynes by using CuI as catalyst and succinic acid as additive. By using this protocol, a wide range of propargylamines was obtained in high yields.

Under mild conditions, iodine promotes the direct alkylation of 1,3-dicarbonyl compounds with benzylic alcohols or benzylic acetates.