Syntheses and X-Ray Crystal Structures of 2-Aminoindenes and Aminocymantrenes

Substituted 2-aminoindenes have been synthesized in almost quantitative yields by reactions of amines such as methylpiperazine, trimethylethylenediamine, 1,4-diaza-cycloheptane and N,N′-dimethylethylenediamine with 2-indanone. The 2-aminoindenes can be deprotonated and reacted with BrMn(CO)₃(Py)₂ to produce the respective aminoindenyl-cymantrenes in yields between 55–70%. The X-ray crystal structures of 2-(methylpiperazine)indenyl-cymantrene 5 (P1 , a = 12.667(3) Å, b = 16.630(3) Å, c = 17.382(3) Å, α = 72.70(3)°, β = 74.59(3)°, γ = 88.66(3)°, V = 3364.1(12) Å ³, Z = 8, R1(2σ(I)) = 4.02%, wR2(2σ(I)) = 10.30%) and the HClO₄ adduct of 2-(trimethylethylenediamine)-indenyl-cymantrene 6 (Cc, a = 23.722(5) Å, b = 6.9080 Å, c = 13.264 Å, β = 111.77(3)°, V = 2018.6(7) Å 3, Z = 4, R1(2σ(I)) = 2.94%, wR2(2σ(I)) = 7.90%) were determined. In both complexes the indenyl-carbon bonded to nitrogen displays significantly longer bonds to manganese [223.5(3)–225.8(3) pm] than the other four carbon atoms [213.3(3)–219.1(3) pm]. The short indenyl-nitrogen bonds of 136.2(4) and 137.8(4) pm are indicative of a substantial multiple bond character. The complexation of Zn²⁺ by the nitrogen atoms of 6 results in significant shifts of the CO stretching frequencies.     

Ir-catalyzed C-H activation in the synthesis of borylated ferrocenes and half sandwich compounds

The complex generated from 1/2[Ir(OMe)(cod)]2 and 4,4'-di-tert-butyl-2,2'-bipyridine catalyzes the regioselective borylation of ferrocenes, CpMn(CO)3 and CpMo(CO)3CH3 with a stoichiometric amount of B2pin2.     

Cooperative effects in binuclear zirconocenes: Their synthesis and use as catalyst in propene polymerization

The mono- and bis-cyclopentadienyl compounds 1-(Cp″)-4-(CH₃)C₆H₄ (1) and 1, 4-(Cp″)₂C₆H₄ (2) (Cp″ = 3,4-dimethylcyclopenta-1,3-diene-1-yl) have been synthesized. The reactions of the lithium salts of 1 and 2 with CpZrCl₃ · dme (dme = dimethoxyethane) and Cp*ZrCl₃(CP* = C₅(CH₃)₅) yielded the mono- and bi-nuclear bridged zirconocenes 1-(Cp″ZrCpCl₂)-4-(CH₃)C₆H₄ (3), 1,4-(Cp″ZrCpCl₂)₂C₆H₄ (4) and 1,4-(Cp″ZrCp*Cl₂)₂C₆H₄ (5). When activated with methylaluminoxane (MAO), the mono- and bi-nuclear zirconocenes 3 and 4 catalyse the polymerization of propene. The influence of the catalyst composition on the polymerization kinetics and molecular weight is discussed.     

Quantum and classical correlations in quantum Brownian motion

We investigate the entanglement properties of the joint state of a distinguished quantum system and its environment in the quantum Brownian motion model. This model is a frequent starting point for investigations of environment-induced superselection. Using recent methods from quantum information theory, we show that there exists a large class of initial states for which no entanglement will be created at all times between the system of salient interest and the environment. If the distinguished system has been initially prepared in a pure Gaussian state, then entanglement is created immediately, regardless of the temperature of the environment and the nonvanishing coupling.     

Quantum information and triangular optical lattices

The regular structures obtained by optical lattice technology and their behavior are analyzed from the quantum information perspective. Initially, we demonstrate that a triangular optical lattice of two atomic species, bosonic or fermionic, can be employed to generate a variety of novel spin-1/2 models that include effective three-spin interactions. Such interactions can be employed to simulate specific one-or two-dimensional physical systems that are of particular interest for their condensed matter and entanglement properties. In particular, connections between the scaling behavior of entanglement and the entanglement properties of closely spaced spins are drawn. Moreover, three-spin interactions are well suited to support quantum computing without the need to manipulate individual qubits. By employing Raman transitions or the interaction of the atomic electric dipole moment with magnetic field gradients, one can generate Hamiltonians that can be used for the physical implementation of geometric or topological objects. This work serves as a review article that also includes many new results.     

Efficient factorization with a single pure qubit and logN mixed qubits

It is commonly assumed that Shor's quantum algorithm for the efficient factorization of a large number N requires a pure initial state. Here we demonstrate that a single pure qubit, together with a collection of log 2N qubits in an arbitrary mixed state, is sufficient to implement Shor's factorization algorithm efficiently.