No abstract

If one considers the benzene spacers as corners and the ethano bridges as edges of polyhedra. C,,H,, is a tetrahedron. CjnHtr a prism, and C,,H,, a cube. The faces of the polyhedra correspond to the openings on the surface of the molecule. an area suri-ounded by n corners corresponding to a [2.] metacyclophane window (71.

[structure: see text] A novel alkali cation selective probe is described which exhibits unique ICT and binding properties, allowing the ratiometric titration of sodium cations in the presence of other alkali metal ions.

Mesitylphosphaacetylene (1b) has been synthesized by AlCl 3 initiated elimination of bis(trimethylsilyl) ether from the phosphaalkene 2b . This new phosphaalkyne undergoes [3+2] cycloaddition reactions with diazo compounds ( → 6a , b ), azides ( → 8a-c ), and nitrile oxides ( → 10a , b ) to yield five-membered heterocyclic products. The mesoionic reaction partners 11 and 13 react with 1b under elimination of CO 2 and COS, respectively, to furnish the 1,3-aza-and 1,3-thiaphospholes 12 and 14 . Reaction of 1b with buta-1,3-diene leads to the diphosphatricyclooctene 18 ; it has been shown that the 1-phosphacyclohexa-1,4-diene 15 (characterized by an X-ray structure analysis of its W(CO) 5 complex 17 ) is an intermediate in the multistep reaction. Moreover, 1b has been characterized by Diels-Alder reactions with the cyclobutadiene 19 and the azacyclobutadiene 21 to afford the Dewar hetarenes 20 and 22 .