A rigid trans-spanning dinitrile ligand.

Abstract

(Fig. la). In contrast, functional groups such as nitriles take on a linear arrangement at nitrogen and necessitate a larger scaffold and more convergent C shape to achieve the same geometries (Fig. lb). Accordingly, multidentate nitriles are commonly oligomeric and polymeric structures and have been successfully used to assemble expansive threedimensional arrays (8,9). Chelating di-and trinitriles are also known, but they invariably bind to the same face of the metal and not to opposing faces (10)(11)(12)(13) MATERIALS AND METHODSThe C-Shaped and S-Shaped Isomers of Bisamide 3. (See Fig. 2.) A 1-to-1 mixture of C-and S-shaped isomers of diacid 2 (1.16 g, 1.17 mmol), thionyl chloride (5 ml), and four drops of N,N-dimethylformamide (DMF) were heated at reflux for 2.5 h (14). The reaction mixture was evaporated to a yellow solid under reduced pressure. The crude product was dissolved in 50 ml of CH2Cl2 and treated with 10 ml of concentrated aqueous ammonium hydroxide. The mixture was stirred vigorously for 1 h and then washed with 1.0 M HCI (twice with 100 ml), then dried over MgSO4. Chromatography on silica gel (MeOH/CH2Cl2, 0.75%) gave the lower-Rf, S-shaped isomer of 3 (400 mg, 35%) and the higher-Rf, C-shaped isomer of 3 (462 mg, 41%

Homoleptic Gold Acetonitrile Complexes with Medium to Very Weakly Coordinating Counterions: Effect on Aurophilicity?

“…All presented [Au(NCMe) 2 ] + [WCA] − salts ([WCA] − =[BF 4 ] − , ( 2 a ) [GaCl 4 ] − ( 2 b ) , [B(CF 3 ) 4 ] − ( 2 c ), [Al(OR F ) 4 ] − ( 2 d )) were prepared through direct oxidation of elemental gold in acetonitrile with nitrosyl salts of weakly coordinating anions [NO] + [WCA] − [Eq. ()]. …”

“…All presented [Au(NCMe) 2 ] + [WCA] À salts ([WCA] À = [BF 4 ] À , [14] (2a)[ GaCl 4 ] À (2b) , [B(CF 3 ) 4 ] À (2c), [Al(OR F ) 4 ] À (2d)) werep repared through direct oxidation of elemental gold in acetonitrile with nitrosyl salts of weakly coordinatinga nions [NO] [14] and by Yaua nd Mingos, [13] according to Eq. (2), [13] and confirmt hat the salt is very reactive and unstable.N evertheless, by pickingt he crystals at low temperature (À30 8C) and under inert conditions, it was possible to determinei ts crystal structure.…”

“…[9] In 1964, the related[ NO] + [ClO 4 ] À was used for M = Au, [10] but the resulting [Au(NCMe) 2 ] + [ClO 4 ] À ,w hich was only characterizedb ye lemental analysis, is highly sensitive to light and water and already decomposesi nt he absence of acetonitrile vapor.L ater,t he more stable [Au(NCMe) 2 ] + [SbF 6 ] À was prepared from [Au(CO) 2 ] + [SbF 6 ] À in superacids, providing the only crystallographicallyc haracterized [Au(NCMe) 2 ] + salt reported to date. [11,12] More recently,Y au and Mingos and Shimizu and Rebek oxidized gold with [NO] + [BF 4 ] À in acetonitrile and obtained [Au(NCMe) 2 ] + [BF 4 ] À , [13,14] acompound highly sensitive towards air,l ight, and water (only vibrational spectroscopy,m ass spectrometry). Yaua nd Mingosi ntroduced the more stable benzonitrile complex[ Au(NCPh) 2 ] + [BF 4 ] À as av ersatile but labile gold(I) intermediate.…”

“…Later, the more stable [Au(NCMe) 2 ] + [SbF 6 ] − was prepared from [Au(CO) 2 ] + [SbF 6 ] − in superacids, providing the only crystallographically characterized [Au(NCMe) 2 ] + salt reported to date . More recently, Yau and Mingos and Shimizu and Rebek oxidized gold with [NO] + [BF 4 ] − in acetonitrile and obtained [Au(NCMe) 2 ] + [BF 4 ] − , a compound highly sensitive towards air, light, and water (only vibrational spectroscopy, mass spectrometry). Yau and Mingos introduced the more stable benzonitrile complex [Au(NCPh) 2 ] + [BF 4 ] − as a versatile but labile gold(I) intermediate .…”

Peptide [4]Catenane by Folding and Assembly

“…Preparation of NMR samples:A gBF 4 (25 mmol) and either the tripeptidel igand 2 or 4 (25 mmol) were mixed in [D 3 ]nitromethane (0.6 mL) at room temperature.F or 3' ',[Au(MeCN) 2 ]BF 4 [17] was used. In all cases,self-assembly was completed within 5min.…”