Synthesis,Structural Characterization and Spectroscopic Properties of [Pt(bddn)]Cl<Subscript>2</Subscript> · 3.5H<Subscript>2</Subscript>O (bddn = 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane)

Abstract The reaction of the potentially tetradentate ligand 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn) with [PtCl₂(CH₃CN)₂] yields a mixture of complexes, where the ligand acts as bidentate SS, or tetradentate 2NS or NSSN. This mixture of complexes SS, 2NS, and NSSN was crystallized with dichloromethane/n-pentane (1:1) and crystals of [Pt(bddn)]Cl₂ (isomer NSSN) were obtained. The complex has been characterized by elemental analyses, mass spectrometry, conductivity, IR, ¹H, ¹³C{¹H}, ¹H{¹⁹⁵Pt}, ¹⁹⁵Pt{¹H}NMR, HSQC and NOESY spectroscopies, and X-ray diffraction. Compound [PtCl₂(bddn)] · 3.5H₂O crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 15.430(7) ?, b = 17.405(4) ?, c = 18.887(7) ?, β = 91.24(2)°, V = 5071(3) ?³, Z = 4, R ₁ = 0.0354, wR₂ = 0.1034. This compound consist of discrete cations [Pt(bddn)]²⁺, Cl⁻ anions and water molecules of crystallization. The platinum(II) is tetracoordinated by two azine nitrogen atoms and two sulfur atoms of the thioether-pyrazole ligand, in a distorted square planar geometry. Graphical Abstract Synthesis, Structural Characterization and Spectroscopic Properties of [Pt(bddn)]Cl ₂ · 3.5H ₂ O (bddn = 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane) Antonio de Leon, Josefina Pons*, Jordi García-Antón, Xavier Solans, Mercè Font-Bardia, Josep Ros* Reaction of the ligand 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn) with [PtCl₂(CH₃CN)₂], yields a mixture of complexes. The mixture was crystallized with dichloromethane/pentane (1:1) and crystals of [Pt(bddn)]Cl₂ · 3.5 H₂O was obtained. Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.     

Analysis of macrolide antibiotics in river water by solid-phase extraction and liquid chromatography-mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS) method was developed for the determination of five macrolides in natural water samples, using kitasamycin as surrogate. The macrolides were extracted from water samples using Oasis HLB cartridges. Pre-concentration factors up to 250 were obtained. Separation was carried out in an end-capped silica-based C18 column and mobile phases consisting of water/acetonitrile mixtures containing ammonium acetate. Detection was performed by mass spectrometry with a single quadrupole and a triple quadrupole using an electrospray interface. The quality parameters obtained with these two approaches were compared. The detection limits of the whole process were about 1 ng l(-1). The recoveries from 250 ml of water samples spiked at 25-125 ng l(-1) level were in the range 85-115%, except for azithromycin levels, which were around 70%. Erythromycin-H2O, clarithromycin and azithromyzin were found, at the sub ng l(-1) level, in the studied rivers.     

Triangular Nickel Complexes Derived from 2‐Pyridylcyanoxime: An Approach to the Magnetic Properties of the [Ni3(μ3‐OH){pyC(R)NO}3]2+ Core

A series of nickel complexes with nuclearity ranging from Ni₃ to Ni₆ have been obtained by treatment of a variety of nickel salts with the 2‐pyridylcyanoxime ligand. The reported compounds have as a common structural feature the triangular arrangement of nickel cations bridged by a central μ₃‐oxo/alkoxo ligand. These compounds are simultaneously the first nickel derivatives of the 2‐pyridylcyanoxime ligand and the first examples of isolated, μ₃‐O triangular pyridyloximate nickel complexes. Magnetic measurements reveal antiferromagnetic interactions promoted by the μ₃‐O and oximato superexchange pathways and comparison of the experimental structural and magnetic data with DFT calculations give an in‐depth explanation of the factors that determine the magnetic interaction in this kind of system.     

Stereoselective Aminoxylation of Biradical Titanium Enolates with TEMPO

A highly efficient and straightforward aminoxylation of titanium(IV) enolates from (S)‐N‐acyl‐4‐benzyl‐5,5‐dimethyl‐1,3‐oxazolidin‐2‐ones with TEMPO has been developed. A wide array of functional groups on the acyl moiety, including alkyl and aryl substituents, olefins, esters, or α‐cyclopropyl, as well as α‐trifluoromethyl groups, are well tolerated. This transformation can therefore produce the α‐aminoxylated adducts in excellent yields with high diastereomeric ratios (d.r.). In turn, parallel additions to the α,β‐unsaturated N‐acyl counterparts give the corresponding γ‐adducts with complete regioselectivity in moderate to good yields. Removal of the piperidinyl moiety or the chiral auxiliary converts the resultant adducts into enantiomerically pure α‐hydroxy carboxyl derivatives, alcohols, or esters in high yields under mild conditions. Finally, a new mechanistic model based on the biradical character of the titanium(IV) enolates has been proposed.     

Elucidating the 2D Magnetic Topology of the ‘Metal–Radical’ TTTA⋅Cu(hfac)2 System

The TTTA ? Cu(hfac)₂ polymer ( 1 ; in which TTTA=1,3,5‐trithia‐2,4,6‐triazapentalenyl, and hfac=(1,1,1,5,5,5)‐hexafluoroacetylacetonate) is one of the most prominent examples of the rational use of the ‘metal–radical’ synthetic approach to achieve ferromagnetic interactions. Experimentally, the magnetic topology of 1 could not be fully deciphered. Herein, the first‐principles bottom‐up procedure was applied to elucidate the nature and strength of the magnetic J_AB exchange interactions present in 1 . The computed J_AB values give rise to a 2D magnetic topology of ferromagnetic dimers (+11.9 cm^?1) coupled through weaker antiferromagnetic interactions (?3.0 and ?3.2 cm^?1) in two different spatial directions. The hitherto unknown origin of the antiferromagnetic interdimer interactions is thus unveiled. By using the 2D magnetic topology, the agreement between calculated and experimental χT(T) data is extraordinary. In the metal–radical TTTA ? Cu(hfac)₂ compound, the computational model transcends the local dimer cluster model owing to strong interactions between metal centers and organic radicals, thereby creating a de facto biradical. In addition, it is shown that the magnetic topology cannot be inferred from the polymeric [TTTA ??? Cu(hfac)₂]_n crystal motif, that is, from its chemical coordination pattern. Instead, one should think in terms of magnetic building blocks, namely, the de facto biradicals.     

A Theoretically‐Guided Optimization of a New Family of Modular P,S‐Ligands for Iridium‐Catalyzed Hydrogenation of Minimally Functionalized Olefins

A library of modular iridium complexes derived from thioether‐phosphite/phosphinite ligands has been evaluated in the asymmetric iridium‐catalyzed hydrogenation of minimally functionalized olefins. The modular ligand design has been shown to be crucial in finding highly selective catalysts for each substrate. A DFT study of the transition state responsible for the enantiocontrol in the Ir‐catalyzed hydrogenation is also described and used for further optimization of the crucial stereodefining moieties. Excellent enantioselectivities (enantiomeric excess (ee) values up to 99 %) have been obtained for a range of substrates, including E‐ and Z‐trisubstituted and disubstituted olefins, α,β‐unsaturated enones, tri‐ and disubstituted alkenylboronic esters, and olefins with trifluoromethyl substituents.     

Implementing PLS for distance-based regression: computational issues

Distance-based regression allows for a neat implementation of the partial least squares recurrence. In this paper, we address practical issues arising when dealing with moderately large datasets (n ~ 10⁴) such as those typical of automobile insurance premium calculations.     

N,N-Dialkyl-2-iodoanilines: a versatile source for the synthesis of Pd(ii) complexes. Synthesis of novel OCP- and CCN-pincer palladium complexes

The reactivity of a series of N,N-dimethyl-2-iodoanilines bearing different chelating "arms" at the 3-position with Pd(2)(dba)(3) has been explored. 3-[(Diphenylphosphino)methyl]-2-iodo-N,N-dimethylaniline reacted with Pd(2)(dba)(3) and PPh(3) under aerobic conditions to give the OCP-pincer complex , which was formed by sequential C(sp(3))-H activation/oxidation at the alpha-position of the aniline N atom. On the other hand, under similar reaction conditions, 3-[2-(dimethylamino)ethyl]-2-iodo-N,N-dimethylaniline afforded the CCN-pincer complex , after a second C-H activation process at the formyl group of the initially formed OCN-pincer complex. In contrast, 2-iodo-3-(1H-1,2,4-triazol-1-ylmethyl)-N,N-dimethylaniline and 2-iodo-3-(pyrazol-1-ylmethyl)-N,N-dimethylaniline reacted with Pd(2)(dba)(3) and PPh(3), respectively, to give the 6-membered azapalladacycles and , in which the aniline nitrogen is merely a spectator substituent. Finally, treatment of iodide complex with Tl(TfO) afforded the CN-bidentate cationic complex. Solid-state structures of palladium complexes, and CH(2)Cl(2).3CH(3)OH.5H(2)O were determined by X-ray analysis.     

Indene-based scaffolds. Design and synthesis of novel serotonin 5-HT6 receptor ligands

A series of novel indene derivatives designed by a scaffold selection gave access to several examples of (Z)-arylmethylideneindenes and indenylsulfonamides that acted as serotonin 5-HT(6) receptor ligands. Different synthetic multistep routes could be applied to these target compounds, each with their own complexity and limitations. A reasonable route involved the (3-indenyl)acetic acids as the key intermediates, and two alternatives were also examined. The first protocol used was a two-step sequence employing a modified Horner-Wadsworth-Emmons reaction, but better results were obtained with a procedure based on the condensation of indanones with the lithium salt of ethyl acetate, followed immediately by dehydration with acid and hydrolysis/isomerization under basic catalysis. (3-Indenyl)acetic acids were transformed to the corresponding acetamides, which were effectively reduced to indenylsulfonamides using an optimized procedure with AlH(3)-NMe(2)Et. The binding at the 5-HT(6) receptor was with moderate affinity (K(i) = 216.5 nM) for the (Z)-benzylideneindenylsulfonamide and enhanced affinity for the simple indenylsulfonamide counterpart (K(i) = 50.6 nM). Selected indenylsulfonamides were then tested, showing K(i) values as low as 20.2 nM.