Palladium–catalysed alkyne alkoxycarbonylation with P,N chelating ligands revisited : a density functional theory study

Authors thank EaStCHEM and the School of Chemistry for support. The Bristol Chemical Synthesis Centre for Doctoral Training (BCS CDT) funded by the Engineering and Physical Sciences Research Council (EPSRC) (EP/G036764/1) and the University of Bristol are thanked for a PhD studentship (to T. A. S.).A revised in situ base mechanism of alkyne alkoxycarbonylation via a Pd catalyst with hemilabile P,N-ligands (PyPPh2, Py = 2-pyridyl) has been fully characterised at the B3PW91-D3/PCM level of density functional theory. Key intermediates on this route are acryloyl (η3-propen-1-oyl) complexes that readily undergo methanolysis. With two hemilabile P,N-ligands and one of them protonated, the overall computed barrier is 24.5 kcal mol-1, which decreases to 20.3 kcal mol-1 upon protonation of the second P,N-ligand. This new mechanism is consistent with all of the experimental data relating to substituent effects on relative reaction rates and branched/linear selectivities, including new results on the methoxycarbonylation of phenylacetylene using (4-NMe2Py)PPh2 and (6-Cl-Py)PPh2 ligand. This ligand is found to decrease catalytic activity over PyPPh2, thus invalidating a formerly characterised in situ base mechanism.PostprintPeer reviewe

A field study of team working in a new human supervisory control system

This paper presents a case study of an investigation into team behaviour in an energy distribution company. The main aim was to investigate the impact of major changes in the company on system performance, comprising human and technical elements. A socio-technical systems approach was adopted. There were main differences between the teams investigated in the study: the time of year each control room was studied (i.e. summer or winter),the stage of development each team was in (i.e. 10 months), and the team structure (i.e. hierarchical or heterarchical). In all other respects the control rooms were the same: employing the same technology and within the same organization. The main findings were: the teams studied in the winter months were engaged in more `planning’ and `awareness’ type of activities than those studies in the summer months. Newer teams seem to be engaged in more sharing of information than older teams, which maybe indicative of the development process. One of the hierarchical teams was engaged in more `system-driven’ activities than the heterarchical team studied at the same time of year. Finally, in general, the heterarchical team perceived a greater degree of team working culture than its hierarchical counterparts. This applied research project confirms findings from laboratory research and emphasizes the importance of involving ergonomics in the design of team working in human supervisory control

Palladium–catalysed Alkyne Alkoxycarbonylation with P,N Chelating Ligands Revisited: A Density Functional Theory Study (dataset)

Computational and experimental (NMR) data for the corresponding article