The present disclosure relates to a ligand compound, a catalyst system for oligomerization, and a method for olefin oligomerization using the same. The catalyst system for oligomerization using the ligand compound according to the present disclosure has excellent catalytic activity, exhibits high selectivity to 1-hexene and 1-octene, and greatly reduces the production of the by-products, thereby enabling efficient preparation of alpha-olefin.

The present application provides, among other things, compounds and methods for metathesis reactions. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and/or stereoselectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and Z-selectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and E-selectivity. In some embodiments, provided technologies are particularly useful for preparing alkenyl fluorides. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-a. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-b.

The present application provides, among other things, compounds and methods for metathesis reactions. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and/or stereoselectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and Z-selectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and E-selectivity. In some embodiments, provided technologies are particularly useful for preparing alkenyl fluorides. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-a. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-b.

The present disclosure relates to a catalyst system comprising i) (a) an N.sup.2-phosphinyl bicyclic amidine chromium salt or (b) a chromium salt and an N.sup.2-phosphinyl bicyclic amidine and ii) an organoaluminum compound. The present disclosure also relate to a process comprising: a) contacting i) ethylene; ii) a catalyst system comprising (a) an N.sup.2-phosphinyl bicyclic amidine chromium salt complex or (b) a chromium salt and an N.sup.2-phosphinyl bicyclic amidine; ii) an organoaluminum compound, and iii) optionally an organic reaction medium; and b) forming an oligomer product in a reaction zone.

The present disclosure relates to a catalyst system comprising i) (a) an N.sup.2-phosphinyl bicyclic amidine chromium salt or (b) a chromium salt and an N.sup.2-phosphinyl bicyclic amidine and ii) an organoaluminum compound. The present disclosure also relate to a process comprising: a) contacting i) ethylene; ii) a catalyst system comprising (a) an N.sup.2-phosphinyl bicyclic amidine chromium salt complex or (b) a chromium salt and an N.sup.2-phosphinyl bicyclic amidine; ii) an organoaluminum compound, and iii) optionally an organic reaction medium; and b) forming an oligomer product in a reaction zone.

The invention relates to a one-pot method for preparing oxido (tetraalkoxido) tungsten compounds according to the general formula [W(O)(OR).sub.4] (I), originating from WCl.sub.6, hexamethyldisiloxane, an alcohol ROH and an amine or NH.sub.3 gas. The invention further relates to the use of a compounds [W(O)(OR).sub.4] (I) and to a substrate which has on one surface a tungsten layer or a layer containing tungsten which are suitable for producing photovoltaic elements, semiconductor elements or car exhaust catalytic converters. The method permits the preparation of defined products in a simple, cost-effective and reproducible manner in high purity and good to very good yields.

In an aspect, an artificial selenomelanin material comprises: one or more selenomelanin polymers; wherein the one or more selenomelanin polymers comprise a plurality of covalently bonded selenomelanin base units; and wherein a chemical formula of each of the one or more selenomelanin base units comprises at least one selenium atom. Optionally, each selenomelanin polymer is a pheomelanin. Preferably, the chemical formula of each of the one or more selenomelanin base units comprises at least one covalent bond with each of the at least one selenium atom.

In an aspect, an artificial selenomelanin material comprises: one or more selenomelanin polymers; wherein the one or more selenomelanin polymers comprise a plurality of covalently bonded selenomelanin base units; and wherein a chemical formula of each of the one or more selenomelanin base units comprises at least one selenium atom. Optionally, each selenomelanin polymer is a pheomelanin. Preferably, the chemical formula of each of the one or more selenomelanin base units comprises at least one covalent bond with each of the at least one selenium atom.

Described herein are IC devices that include molybdenum or a molybdenum compound, such as compounds including oxygen or nitrogen. The molybdenum may be deposited at a high concentration, e.g., at least 50% atomic density. Also described herein are mid-valent molybdenum precursors for depositing molybdenum, and reactions for producing the mid-valent molybdenum precursors. For example, the molybdenum precursors may be generated by reacting a higher-valent molybdenum compound with an amidinate or a formamidinate.

Provided are compositions comprising isotactic polyethers. Methods of making isotactic polyethers, and uses thereof are also disclosed. Also provided are bimetallic complexes that can be used as catalyst. Methods of making isotactic polyethers and bimetallic complexes and uses thereof are also disclosed. For example, a racemic bimetallic (salalen)CrCl polymerization catalyst was prepared and used alkyl diol, PO-oligomer triols, and aPPO and PCL diols as CSAs in order to produce α,ω-hydroxy telechelic iPPO. These telechelic polymers have controlled molecular weights and are semicrystalline. Amorphous α,ω-hydroxy telechelic PPO can also be produced by increasing the reaction temperature in conjunction with the use of CSAs.