The strong Lewis acid tungsten oxo complex of calix[4]arene can be obtained in both hydrated and non-hydrated forms. This complex coordinates a water molecule inside the cavity via strong O···W interactions with relatively short distances of 2.284(4) and 2.329(2) Å for the tungsten oxo complex of calix[4]arene··H2O·aniline (1), and the tungsten oxo complex of calix[4]arene·H2O·toluene (2·toluene), respectively. The strong interactions are also deduced by the relatively high H2O elimination temperature observed by TGA and DSC (above 200 °C). The coordinated water molecule inside the calix[4]arene cavity is characterized by a strong IR absorption at 3616 cm–1, and a narrow resonance at ~1.2 ppm (the chemical shifts of the uncoordinated water are 1.55 and 1.60 ppm in C6D6 and CDCl3, respectively). This water molecule gives rise to H-bonds with aniline in 1. The tungsten oxo complex of 5,11,17,23-tetrabromocalix[4]arene (4), also binds H2O as the characteristic signatures are observed. The successful removal of H2O in 2, is performed under mild conditions using bis(tetrahydrofuran)-uranyl nitrate as a competitive Lewis acid. When this reaction is performed in acetonitrile, butyronitrile or tert-butylnitrile, the corresponding tungsten oxo complexes of calix[4]arene·acetonitrile (3), ·butyronitrile (5), and ·tert-butylnitrile (6) are obtained. The use of uranyl as a H2O abstractor is unprecedented. The X-ray structure of 3 consists of a tungsten oxo complex of calix[4]arene coordinated by an acetonitrile molecule (d(W···N = 2.412(2) Å). The tetra-5,11,17,23-choromethyl-25,26,27,28-tetrahydroxycalix[4]arene reacts with M(O)Cl4 (M = Mo, W) in a 1:1 stoichiometry, via a tetra Friedel–Crafts addition of benzene or toluene, followed by a lower-rim complexation of the metal oxide, to form "flower-shaped" calix[4]arenes. This "one pot" double functionalization is unprecedented.Key words: calix[4]arene, tungsten, molybdenum, X-ray, host–guest, Friedel–Crafts, Lewis acid, uranyl, DSC, TGA.

The 5,11- and 5,17-diisocyano-25,26,27,28-tetra-n-propoxycalix[4]arene bridging ligands (calix(NC)2) have been prepared in four steps with 34 and 30% global yields, respectively. Their corresponding Ag(I) complexes have been prepared from the direct reaction of the ligand with AgBF4 and are characterized from various spectroscopic and physical techniques. The MALDI-TOF spectra indicate the presence of polymers or oligomers of the type {Ag(calix(NC)2)(BF4)}n. The compounds have been characterized further from TGA, DSC, and XRD and compared with the oligomeric species 5,11,17,23-tetraisocyano-25,26,27,28-tetra-n-propoxycalix[4]arene silver(I) (as a BF4– salt).Key words: silver, calix[4]arene, polymer, isocyanide, photosensitive, thermal gravimetric analysis.

In a search for minor ryanoids from the plant Ryania Speciosa Vahl, we recently characterized 11 new members of that family of natural compounds. Most of them represent ryanodine (1) and dehydroryanodine (2) with a modified stage of oxidation in ring C. A second member of the new 4-deoxy series has been identified.Key words: minor natural ryanoids, ryanodine, dehydroryanodine, deoxyryanoids.

The title compound (10) was prepared from the calix[4]arene precursor (11) to form the ligand 5,11‐bis(methyl(diphenylphosphino))‐25,26,27,28‐tetra‐n‐propoxy calix[4]arene (12), which was reacted with [Rh(COD)Cl]2 (COD = 1,5‐cyclooctadienyl) and TlPF6 as chloride scavenger, in 31% overall chemical yield. The dimer structure in solution was demonstrated by the measurements of the 31P NMR spin‐lattice relaxation time (T1) in comparison with the ligand itself. Computer modeling shows that the dimer macrocycle exhibits many possible conformers, including some with obvious steric hindrance about the Rh atom, but no apparent ring stress. 10 was tested for the catalytic homogeneous hydroformylation of hex‐1‐ene and compared with other closely related analogue systems recently reported in the literature.magnified image