Cyclometallated ruthenium complexes with P-stereogenic monophosphines containing a polycyclic aromatic substituent

Reactions of optically pure P-stereogenic ortho-tolyl substituted phosphines with [RuCl2(p-cymene)]2 afforded the corresponding kP-coordinated ruthenium(II) dichlorides (C1′, C2') even in the presence of sodium acetate. In contrast, the ruthenium cyclometallated (k2-C,P) complexes (C3eC9) were obtained with phosphines containing a polycyclic aromatic substituent (L3-L9), namely 1-naphthyl, 9-phenanthryl or 1-pyrenyl. Some diastereoselectivity in the cyclometallation process has been observed for the most bulky ligands. The new compounds have been used as catalytic precursors in the reduction of acetophenone to 1-phenylethanol by transfer hydrogenation

Lithium cations in a self-assembled electrostatic nanocapsule

Cascade self-assembly of small components, without the employment of preformed hosts, yielded a {Ni12Li2} nanometric capsule with multiple endo- and exo-guests (water molecules, Li+, and Et3NH+ cations) linked to selective hydrophilic and hydrophobic binding sites of NiII hexanuclear metallamacrocycles. The synthesis was achieved by using (Bu4N)N3 as a starting reagent instead of the conventional sodium azide to selectively introduce the Li+ cations

Biaryl formation in the synthesis of endo and exo-platinacycles

The reactions of cis-[Pt2(4-MeC6H4)4(m-SEt2)2] with bifunctional ligands ArCH NCH2(2-XC6H4) containing a C-X bond at the ortho positions of the benzyl ring (Ar = 4-ClC6H4, X = Br (1d); Ar = 2,4,6-(CH3)3C6H2, X = Br (1e); Ar = 2,4,6-(CH3)3C6H2, X = Cl (1f); Ar = 2-CH3C6H4, X = Br (1h); Ar = 2,6-F2C6H3, X = Br (1i)) in refluxing toluene were studied. Several types of platinum(II) cyclometallated compounds containing a biaryl linkage were obtained: i) endo-five-membered with a Pt-C(sp2) bond (2d, 2h), ii) endo-six-membered with a Pt-C(sp3) bond (2e, 2f), and iii) exo-five membered with a Pt-C(sp2) bond (2i). The formed biaryl linkage involves the metallated ring for 2i and the non-metallated ring for the endo-metallacycles. The reaction of compounds 2 with PPh3 produced the corresponding phosphine derivatives, some of which (3d, 3e, 3h and 3i) were characterised crystallographically. In addition, compound [PtBr{2-CH3C6H3C6H4CH NCH2(2-C6H4Br)}SEt2] (2c) containing a seven-membered endo-metallacycle was also obtained and characterised crystallographically

Kinetico-mechanistic studies on the formation of seven-membered [C,N]-platinacycles: the effect of methyl or fluoro substituents on the aryl ancillary ligands

The reactions of dinuclear [Pt2(4-RC6H4)4(μ-SEt2)2] (R = Me or F), or mononuclear [Pt(4-RC6H4)2(SMe2)2] (R = Me or H), platinum(II) compounds with imines of the general formula 2-X,6-YC6H3CH[double bond, length as m-dash]NCH2Ph (X = Br, Y = F; X = Cl, Y = F; X = Br, Y = H) produced seven-membered [C,N]-platinacycles. The reaction consists of the initial formation of cyclometallated platinum(IV) compounds followed by a three step process: reductive elimination, isomerisation of the resulting non-cyclometallated intermediate and a final cycloplatination process. Combined 1H NMR and UV-Vis kinetico-mechanistic studies indicated that the rate determining step of the process depends on the nature of the aryl-Pt ligand (phenyl, p-tolyl or p-fluorophenyl)

Na2MnIII6 LnIII clusters with a non-equivalent core: chiral vs. meso isomerism

A wide family of clusters with the Na2MnIII6 LnIII core derived from an enantiomerically pure or a racemic mixture of Schiff bases lead to the characterization of a unique case of chiral/meso isomers with C3/D3d symmetry respectively, involving the rearrangement of the cluster bond parameters and the change from hepta- to hexacoordination of the central LnIII cation

Synthesis of polycycles by single or double domino nucleophilic substitution. Diels-Alder reaction

New hexacyclo and octacyclo compounds have been synthesized by a short route whose key step consists of a single or double domino nucleophilic substitution of neopentyl‐type iodides with potassium cyclopentadienide, followed by intramolecular Diels-Alder cycloaddition

Template arrangement of {Ni3(&m3-OH)(SO4)(R-NO)2}+ fragments around Na+ cations: An unprecedented {Ni12Na} unit linked by oximate and sulfate bridges

Anovel {−Ni12Na2-Ni-}n chain has been characterized fromthe reaction between 2-pyridylcyanoxime, (pyC{CN}NOH), and nickel(II) sulfate. The template synthesis around a Na+ cation gives an unprecedented arrangement of four nickel triangles coordinated to the central sodium ion by sulfato bridges

Polymorphism of Sildenafil: A New Metastable Desolvate

A new anhydrous polymorph of the free base of sildenafil and two solvates (acetonitrile and propanenitrile) have been discovered and fully characterized. The new polymorph can be considered a desolvate of the acetonitrile solvate and is related to the most stable form I by morphotropism. The new polymorph can only be obtained by desolvation of the acetonitrile solvate. Thus, this study is a new example of the importance of this multicomponent family of solid forms in the discovery of new polymorphs of active pharmaceutical ingredients

Morphotropism and 'Quasi-Isostructurality' in the Three High Z′ Concomitant Polymorphs of Efinaconazole

The crystal structures of the three efinaconazole anhydrous forms have been solved by single-crystal X-ray diffraction showing a very rare case of nearly isostructural polymorphism. The analysis of their crystal structures revealed that forms I and III are 'quasi-isostructural' polymorphs and are morphotropically related to form II. The identical conformational and supramolecular environment can explain the concomitant polymorphism phenomenon observed for this important active pharmaceutical ingredient

Anionic guests in prismatic cavities generated by enneanuclear nickel metallacycles

The combination of polydentate aminated ligands with the 2-pyridyloxime-nickel-azide system leads to series of clusters with unprecedented topologies. Among them, a remarkable family of {Ni9} metallacycles that are capable of selective encapsulation of azide/halide anions in a cryptand-like cavity through hydrogen-bond interactions has been characterized