The complete sequence of steps of a tentative catalytic cycle for intramolecular hydroamination/cyclisation (IHC) of 4,5-hexadien-1-ylamine (1) by a prototypical cationic [Cp(2)ZrCH(3)](+) zirconocene precatalyst (2) has been examined by employing a gradient-corrected DFT method. The predicted smooth overall reaction energy profile is consistent with the available experimental data, thereby pro...

Femtosecond ring-opening dynamics of 1,3-cyclohexadiene (CHD) in gas phase upon two-photon excitation at 400 nm (=3.1 eV) was investigated by time-resolved photoelectron spectroscopy using 42 nm (=29.5 eV) high harmonic photons probing the dynamics of the lower-lying occupied molecular orbitals (MOs), which are the fingerprints of the molecular structure. After 500 fs, the photoelectron intensi...

A series of iso-structural complexes [(SIPr)AgX] (X = Cl, Br, I, OTf; SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolidene) were synthesised, including the first example of a N-heterocyclic carbene silver(I) complex containing an O-bound triflate. Bond Energy Dissociation and Natural Orbitals for Chemical Valence bond analyses (BEDA & ETS-NOCV) revealing a significant NHC → M σ-back-donation, whi...

The regulation of disulphide stress in actinomycetes such as Streptomyces coelicolor is known to involve the zinc-containing anti-sigma factor RsrA that binds and inactivates the redox-regulated sigma factor sigmaR. However, it is not known how RsrA senses disulphide stress nor what role the metal ion plays. Using in vitro assays, we show that while zinc is not required for sigmaR binding it is...

The rates of C H bond activation for various alkanes by [(N-N)Pt(Me)(TFEd(3))](+) (N N = Ar N C(Me) C(Me) N Ar; Ar = 3,5-di-tert-butylphenyl; TFE-d(3) = CF(3)CD(2)OD) were studied. Both linear and cyclic alkanes give the corresponding alkene-hydride cation [(N-N)Pt(H)(alkene)](+) via (i) rate determining alkane coordination to form a C H sigma complex, (ii) oxidative cleavage of the coordinated...

An efficient methodology for the synthesis of new and highly functionalized 2-azafluorenones via a three-component domino reaction involving C1-aryl acylation, C3-thiolation, and C4-cyanation has been developed. This domino reaction enables successful assembly of three new sigma bonds including a C-S bond and a C-N bond in a one-pot operation. Features of this strategy include the mild conditio...

The nuclear magnetic shielding tensor is a sensitive probe of the local electronic environment, providing information about molecular structure and intermolecular interactions. The magnetic shielding tensor of the water proton has been determined in hexagonal ice, but in liquid water, where the tensor is isotropically averaged by rapid molecular tumbling, only the trace of the tensor has been m...

Regioselective reaction of a lithium organocuprate (R2CuLi) and a polyconjugated carbonyl compound affords a remote-conjugate-addition product. This reaction proceeds particularly cleanly when the conjugation is terminated by a C-C triple bond. The reaction pathways and the origin of the regioselectivity of this class of transformations are explored with the aid of density functional calculatio...

Transcription initiation at the sigma 54-dependent glnAp2 promoter was studied to follow the state of polymerase as RNA synthesis begins. Sigma 54 polymerase begins transcription in abortive cycling mode, i.e. after the first bond is made, approximately 75% of the time the short RNA is aborted and synthesis must be restarted. Polymerase is capable of abortive initiation until it reaches a posit...

Molecular junction is a promising candidate for devices nowadays, especially the conjugated molecule with much higher conductance compared to sigma bond alkanes. The decay constant β, which describes the length-dependent conductance, is one of the most important parameters in molecular junctions. To investigate the decay constant, we introduce the exponential dependence first, and then explain ...