Crystal Structure of Antitubercular Complex: <Emphasis Type="Italic">cis</Emphasis>-(chloro)-[<Emphasis Type="Italic">N,N</Emphasis>′-<Emphasis Type="Italic">bis</Emphasis>-(diethyl-2,2′-bipyridine-3,3′-dicarboxylate)]ruthenium(II) Monohydrate

Abstract  Diethyl-2,2′-bipyridine-3,3′-dicarboxylate (3 or L) reacts with RuCl₃ · 3H₂O to give cis-(Cl)-[Ru(L)₂Cl₂] · H₂O (4) and structure of the complex was determined by spectral (IR, ¹H-NMR), and mass spectroscopic data, elemental analyses and X-ray crystallography. The structure is solved in triclinic, space group p-1 with a = 10.658 (2), b = 12.446 (3), c = 14.186 (5) ?, α = 104.856 (3), β = 108.704 (3), γ = 94.973 (2)°, V = 1693.2 (8) ?³, Z = 2 with final R = 0.012. The geometry of the complex is shown to be a distorted octahedral with four nitrogens of two 2,2′-bipyridyl ligands in two different planes with Ru–N distance as 2.021 (2)−2.071 (3) ?. The cis-position is occupied by two chloride atoms with Ru–Cl distance as 2.4156 (12) and 2.4167 (13) ?. The trans-axial Cl2–Ru1–N and Cl1–Ru1–N4 angles are respectively, 172.42 (7) and 174.12 (7)°. A weak hydrogen bonding is observed between the two chlorides and hydrogens of neighbouring molecule [C–H···Cl distance as 2.72, 2.77 (4) ?]. A second type of weak hydrogen bonding is also observed between the oxygens of carboxylate groups and hydrogens of a neighbouring molecule [C–H···O distance as 2.53, 2.56 and 2.34 (4) ?]. Graphical Abstract  The structure of anti-tubercular precursor complexes, cis-(chloro)-[N,N′-bis-(diethyl-2,2′-bipyridine-3,3′-dicarboxylate)]ruthenium(II) monohydrate is solved by single crystal X-ray diffraction analysis which reveals geometry of the complex to be a distorted octahedral with four nitrogens of two 2,2′-bipyridyl ligands in two different planes. The cis-position is occupied by two chloride atoms.      

Experimental study of neutral-current and charged-current neutrino cross sections

Samples of 9200 muon-neutrino and 3800 muon-antineutrino interactions on nuclei were obtained with the fine-grain calorimeter of the CHARM Collaboration at the CERN 200 GeV narrow-band neutrino beam. The interactions were classified as either neutral-current or charged-current processes on an event-by-event basis. Neutral-current and charged-current cross sections in neutrino and antineutrino interactions are presented. From these results we deduce a statistically significant contribution of right-handed coupling to the neutral hadronic current, and a value of the electroweak mixing angle corresponding to sin²θ = 0.220 ± 0.014.     

Experimental study of differential cross sections dσdy in neutral current neutrino and antineutrino interactions

We present differential cross sections dσ/dy corrected for resolution and acceptance, for events induced by both the neutral- and charged-current interactions of neutrinos and antineutrinos. They are based on 8553 neutrino and 3578 antineutrino events obtained using the CHARM fine-grain calorimeter in the CERN 200 GeV narrow-band beam. From these differential cross sections we demonstrate that the coupling strength of the weak neutral current to the strange quark is compatible with being equal to that of the down quark. Assuming this equality we then describe the weak neutral current in terms of one parameter, sin²θ, which we find to be 0.222 ± 0.016. The charged-current differential cross sections yield values of the fractional momentum-weighted content of the nucleon for non-strange (0.12 ± 0.04) and strange (0.06 ± 0.04) sea quarks. Furthermore, from the strength of the allowed y² term in the neutral-current differential cross sections we put a limit of 3% on the presence of scalar or pseudoscalar contributions to the weak neutral current. This can alternatively be expressed in terms of the Callan-Gross violation parameter R, where we find R = 0 .10 ± 0.10.     

Layer-by-layer surface freezing of linear alcohols at the graphite/liquid interface

Differential scanning calorimetry (DSC), incoherent elastic neutron scattering, and neutron diffraction are used to demonstrate the presence of adsorbed solid multilayers of linear alcohols at the graphite-liquid alcohol interface. All alcohols studied (C(5)-C(18)) are found to form at least one monolayer. In addition all the even alcohols investigated (C(6)OH to C(18)OH) show multilayer formation. However, only the short odd alcohols (C(5)OH to C(11)OH) clearly exhibit additional features indicating multilayer formation.     

“Hummingbird” Behaviour of N‐Heterocyclic Carbenes Stabilises Out‐of‐Plane Bonding of AuCl and CuCl Units

An N‐heterocyclic carbene substituted by two expanded 9‐ethyl‐9‐fluorenyl groups was shown to bind an AuCl unit in an unusual manner, namely with the Au?X rod sitting out of the plane defined by the heterocyclic carbene unit. As shown by X‐ray studies and DFT calculations, the observed large pitch angle (21°) arises from an easy displacement of the gold(I) atom away from the carbene lone‐pair axis, combined with the stabilisation provided by weak CH???Au interactions involving aliphatic and aromatic H atoms of the NHC wingtips. Weak, intermolecular Cl???H bonds are likely to cooperate with the H???Au interactions to stabilise the out‐of‐plane conformation. A general belief until now was that tilt angles in NHC complexes arise mainly from steric effects within the first coordination sphere.     

A convenient one-pot synthesis of boroxoles from diboronic acid

The preparation of the boroxole motif traditionally relies on a 3-step process and the use of n-butyl lithium that can limit substrate scope. Herein during our exploration toward novel RORγ inhibitors, we identified a convenient one-pot preparation of the motif in good yields with good substrate scope.     

Efficient asymmetric hydrogenation of olefins with hydrazine-derived diphosphoramidites

Enantiopure, BINOL-derived diphosphoramidites built upon an achiral hydrazine spacer are efficient ligands for the hydrogenation of 2-(acetylamino)-3-(aryl)-propenoic methyl esters. The activity and enantioselectivity of the hydrazine derivatives were shown to be markedly influenced by the nature of the two NR substituents, symmetrical but bulky R groups leading to the best results. A diphosphosphoramidite obtained from (t)BuHNNH(t)Bu resulted in ee's as high as 95%. The present results contradict previous reports on "short" diphosphoramidites.     

2-Aminobenzamide and 2-Aminobenzoic Acid as New MALDI Matrices Inducing Radical Mediated In-Source Decay of Peptides and Proteins

One of the mechanisms leading to MALDI in-source decay (MALDI ISD) is the transfer of hydrogen radicals to analytes upon laser irradiation. Analytes such as peptides or proteins may undergo ISD and this method can therefore be exploited for top-down sequencing. When performed on peptides, radical-induced ISD results in production of c- and z-ions, as also found in ETD and ECD activation. Here, we describe two new compounds which, when used as MALDI matrices, are able to efficiently induce ISD of peptides and proteins: 2-aminobenzamide and 2-aminobenzoic acid. In-source reduction of the disulfide bridge containing peptide Calcitonin further confirmed the radicalar mechanism of the ISD process. ISD of peptides led, in addition to c- and z-ions, to the generation of a-, x-, and y-ions both in positive and in negative ion modes. Finally, good sequence coverage was obtained for the sequencing of myoglobin (17 kDa protein), confirming the effectiveness of both 2-aminobenzamide and 2-aminobenzoic acid as MALDI ISD matrices.