A structural variability of copper(I) chloride-tetrahydrothiophene adducts crystallizing in polymeric forms and exhibiting polymorphism: The role of the solvent

The function of the solvent in the self-assembling mode of [CuCl] with tetrahydrothiophene is reported. Copper(l) chloride has been used in the form of [CuCOCl] _n , which is slightly soluble in the most common solvents, and to allow an homogeneous phase reaction. The reaction of [CuCOCl] _n with THT gave [(CuCl)₂(THT)₃] _x ,1, in CH₃OH, [(CuCl)(THT)₂] _x ,2 in THF [(CuCl)(THT)] _x ,3, in CH₂Cl₂, and [(CuCl)₃(THT)₂] _x ,4, in DME. Compound1 consists of polymeric chains of centrosymmetric Cu₂Cl₂ dinuclear units bridged by THIT molecules running parallel to the [101] axis. In the structure of2 we found polymeric layers generated from the [(CuCl)(THT)] asymmetric unit by the center of symmetry and by the twofold axis. In compound3 the structure consists of layers generated through the center of symmetry by the [(Cu₂Cl₂)(THT)₂] asymmetric unit, while4 consists of layers generated through the center of symmetry by the [(Cu₃Cl₃)(THT)₂] asymmetric unit. Crystallographic details are as [ollows:2 is monoclinic, space group P2₁/c.a=9.657(3) A,b=6.441(2) A,c=11.459(3) A,\=111.96(2)°,V=661.0(4) A³. andR=0.075;3 is monoclinic, space group P2₁/n,a=19.327(7) A,b=6.703(2) A,c=10.116(3) A,ß=103.04(3)°,V=1276.7(7) A³ andR=0.043:4 is triclinic, space group Pl,a=12.513(2) A,b=6.698(1) A,c=9.651(1) A,=91.98(1)°,\=107.86(1)°,=74.59(1)°,V=741.2(2) A³, andR=0.044.     

Reactions of Alkynes with [RuCl(cyclopentadienyl)] Complexes: The Important First Steps

Cyclopentadienyl–ruthenium half‐sandwich complexes with η²‐bound alkyne ligands have been suggested as catalytic intermediates in the early stages of Ru‐catalyzed reactions with alkynes. We show that electronically unsaturated complexes of the formula [RuCl(Cp^)(η²‐RC≡CR′)] can be stabilized and crystallized by using the sterically demanding cyclopentadienyl ligand Cp^ (Cp^=η⁵‐1‐methoxy‐2,4‐tert‐butyl‐3‐neopentyl‐cyclopentadienyl). Furthermore we demonstrate that [RuCl₂(Cp^)]₂ is an active and regioselective catalyst for the [2+2+2] cyclotrimerization of alkynes. The first elementary steps of the reaction of mono(η²‐alkyne) complexes containing {RuCl(Cp*)} (Cp*=η⁵‐C₅Me₅) and {RuCl(Cp^)} fragments with alkynes were investigated by DFT calculations at the M06/6‐31G* level in combination with a continuum solvent model. Theoretical results are able to rationalize and complement the experimental findings. The presence of the sterically demanding Cp^ ligand increases the activation energy required for the formation of the corresponding di(η²‐alkyne) complexes, enhancing the initial regioselectivity, but avoiding the evolution of the system towards the expected cyclotrimerization product when bulky substituents are present. Theoretical results also show that the electronic structure and stability of a metallacyclic intermediate is strongly dependent on the nature of the substituents present in the alkyne.     

Minimal Periodic Orbit Structure of 2-Dimensional Homeomorphisms

We present a method for estimating the minimal periodic orbit structure, the topological entropy, and a fat representative of the homeomorphism associated with the existence of a finite collection of periodic orbits of an orientation-preserving homeomorphism of the disk D². The method focuses on the concept of fold and recurrent bogus transition and is more direct than existing techniques. In particular, we introduce the notion of complexity to monitor the modification process used to obtain the desired goals. An algorithm implementing the procedure is described and some examples are presented at the end.