The authors introduce the notion of crown-like orders and introduce powerful tools for counting the endomorphisms of orders of this type. r r r r r r r r @ @ @ @ @ @ 1 3 5 7 2 4 6 8 r r r r r r r r @ @ @ @ @ @ 3 3 3 3 3 3 3 1 3 5 7 2 4 6 8 Figure 1: The fence and crown of order 4 r r r r r r r r r r r r · · · · · · @ @ @ @ @ @ @ @ @ @ −5 −3 −1 1 3 5 −4 −2 0 2 4 6 Figure 2: The infinite fence F

Rare-earth metal alkyl tri(tert-butoxy)silanolate complexes [Ln{mu,eta2-OSi(O(t)Bu)3}(CH2SiMe3)2]2 (Ln = Y (1), Tb (2), Lu (3)) were prepared via protonolysis of the appropriate tris(alkyl) complex [Ln(CH2SiMe3)3(thf)2] with tri(tert-butoxy)silanol in pentane. Crystal structure analysis revealed a dinuclear structure for with square pyramidal geometry at the yttrium centre. The silanolate ligan...

This paper describes a synthetic approach to a novel D-glucose-conjugated 15-crown-5 ether having a spiroketal structure starting from a 1-C-vinylated glucose derivative. The approach consists of the glycosylation of the vinylated glucose derivative to give an ethyleneoxy spacer derivative using bismuth(III) triflate, the conversion of the 1-C-vinyl group of the glucoside produced into a carbox...