Allylic C-H acetoxylation with a 4,5-diazafluorenone-ligated palladium catalyst: a ligand-based strategy to achieve aerobic catalytic turnover

Pd-catalyzed C-H oxidation reactions often require the use of oxidants other than O(2). Here we demonstrate a ligand-based strategy to replace benzoquinone with O(2) as the stoichiometric oxidant in Pd-catalyzed allylic C-H acetoxylation. Use of 4,5-diazafluorenone (1) as an ancillary ligand for Pd(OAc)(2) enables terminal alkenes to be converted to linear allylic acetoxylation products in good yields and selectivity under 1 atm O(2). Mechanistic studies have revealed that 1 facilitates C-O reductive elimination from a π-allyl-Pd(II) intermediate, thereby eliminating the requirement for benzoquinone in this key catalytic step.     

Action of Weyl group on zero-weight space

For any simple complex Lie group, we classify irreducible finite-dimensional representations ρ for which the longest element $w_0$ of the Weyl group acts non-trivially on the zero-weight space. Among irreducible representations that have zero among their weights, $w_0$ acts by ±Id if and only if the highest weight of ρ is a multiple of a fundamental weight, with a coefficient less than a bound that depends on the group and on the fundamental weight.     

Study of the deformation characteristics of window security film by digital image correlation techniques

This paper presents a speckle-displacement measurement technique based on the digital image correlation to study the notch sensitivity and crack bridging of window security film. It is used to protect existing glazing against hurricanes, blast and terrorist explosions. The window security film is laminated to the interior side of the glass window by means of a special adhesive. When the glass is breaking, the window film keeps all glass fragments together.The proposed sub-pixel registration of the displacement field is achieved using a calculation technique based on the centre of mass localization of the complex spectrum. This approach increases the computational efficiency for displacements smaller than one pixel and performs with high precision when optimal values of the input correlation parameters are used. In order to achieve a high accuracy of the algorithm, optimization of these input image correlation parameters is offered. For larger displacements an iterative procedure which preserves the precision is successfully implemented.The speckle pattern is created by small white dots sprayed on the previously black painted film surface. As a result, white light illumination can be used which significantly simplifies the experiments.     

Kinematics of haylage bale in 3D space as a body of one fix point and two rotations

This paper presents mechanical-mathematical matrix simulation of haylage bale kinematics in 3D space as a body of one fix point and two rotations. There are defined: the matrices of transition from the coordinate system connected stationary with the body to the starting (global) coordinate system; the position vector, absolute linear speed and absolute linear acceleration of bale arbitrary point; the vector of absolute angular velocity and absolute angular acceleration projected in the starting and in the local coordinate systems of the body. Numerical example is provided.     

Intercalation of Coordinatively Unsaturated FeIII Ion within Interpenetrated Metal–Organic Framework MOF‐5

Coordinatively unsaturated Fe^III metal sites were successfully incorporated into the iconic MOF‐5 framework. This new structure, Fe^III‐iMOF‐5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single‐crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid‐state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe^III, whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe^III ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn^II within the MOF‐5 SBU. This new MOF structure displays the potential for metal‐site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials.     

Synthesis and Isolation of Organogold Complexes through a Controlled 1,2‐Silyl Migration

During our efforts toward the synthesis of naturally occurring polyprenylated polycyclic acylphloroglucinol using a Au^I‐catalyzed 6‐endo dig carbocyclization, we isolated stable vinyllic gold intermediates. Optimization lead to isolated yields of up to 98 %, using 2‐(di‐tert‐butylphosphino)biphenyl as the ligand. This transformation is derived from a silyl rearrangement that can be fully controlled according to the nature of the substituent on the ynone. This selective transformation does not require basic conditions to prevent protodeauration. These vinylgold complexes are the first isolated intermediates during a silyl migration with gold(I). More than 16 new organogold complexes were synthesized and characterized by single‐crystal X‐ray diffraction. Reactivity of these complexes is also presented.