All-nitrogen crowns

All-nitrogen crowns having the nitrogens predominantly unsubstituted. . 184... 

Almost as soon as Pedersen announced his discovery of the crown ethers (see Chaps. 2 and 3) it was recognized by many that these species were similar to those prepared by Busch and coworkers for binding coinage and transition metals (see Sect. 2.1). The latter compounds contained all or a predominance of nitrogen and sulfur (see also Chap. 6) in accordance with their intended use. The crown ethers and the polyazamacrocycles represented two extremes in cation binding ability and preparation of the intermediate compounds quickly ensued. In the conceptual sense, monoazacrowns are the simplest variants of the macrocyclic polyethers and these will be discussed first. 

This geometry is undoubtedly imposed by the skeletal stabilizing unit. Other eight membered phosphorus(III)-nitrogen rings, (MePNMe)i, (9) and (PrNO G NP) (11) are crown shaped containing all chemically equivalent phosphorus atoms. In XI, because the phosphorus atoms are of two sets and one set is in a highly protected environment, the possibility of selective, "cavitand," coordination at phosphorus sites exists. 

MeCN)][SbCl6]3 (106) have also been isolated. The dication has bismuth encompassed by the crown ether and bonded to all ether oxygen atoms, and the chlorine atom [Bi-Cl 2.479(6) A] and the pair of acetonitrile nitrogen atoms [Bi-N 2.82(2) and 2.86(3) A] are bound from the opposite side to the crown ether. The trication adopts a sandwich structure in which bismuth is bound to all four oxygen atoms of each crown ether [Bi-0 2.436(5) and 2.545(5) A]. The acetonitrile nitrogen atom occupies a position between the two ligands [Bi-N 2.650(9) A],... 

General. Toluene, chlorobenzene, and o-dichlorobenzene were distilled from calcium hydride prior to use. 4-Dimethylaminopyridine (Aldrich Chemical Co) was recrystalled (EtOAc), and the other 4-dialkylaminopyridines were distilled prior to use. PEG S, PEGM s, PVP s, and crown ethers were obtained from Aldrich Chemical Co., and were used without purification. BuJ r and BU. PBr were recrystallized (toluene). A Varian 3700 VrC interfaced with a Spectraphysics SP-4000 data system was used for VPC analyses. A Dupont Instruments Model 850 HPLC (also interfaced with the SP-4000) was used for LC analyses. All products of nucleophilic aromatic substitution were identified by comparison to authentic material prepared from reaction in DMF or DMAc. Alkali phenolates or thiol ates were pre-formed via reaction of aqueous NaOH or KOH and the requisite phenol or thiophenol in water under nitrogen, followed by azeotropic removal of water with toluene. The salts were transferred to jars under nitrogen, and were dried at 120 under vacuum for 20 hr, and were stored and handled in a nitrogen dry box. 

All of our results Indicate that Increased productivity Is associated with reduced budworm success. In the Montana study this was evidenced by the relationship between budworm Infestation Intensity and bole radius. In the Barley Canyon study, the relationship between budworm growth and crown ratio, the 5 year growth Increment, and total nitrogen support this conclusion as well. Assuming that productivity declines with age, the positive correlation between budworm success and age also Implies that a decline In vigor Increases tree susceptibility to budworm. 

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