A pseudo‐cage complex of silver(I) with tripodal tetraamine having benzyl end groups, {tris[2‐(benzylamino)ethyl]amine‐κ4N}silver(I) perchlorate

The synthesis and crystal structure of {tris­[2‐(benzyl­amino)­ethyl]­amine‐κ⁴N}silver(I) perchlorate, [Ag(C₂₇H₃₆N₄)]ClO₄ or [Ag(bz₃tren)]ClO₄ {bz₃tren is tris­[2‐(benzyl­amino)­ethyl]­amine or N,N′,N′′‐tri­benzyl­tris(2‐amino­ethyl)­amine} are reported. The Ag atom is coordinated to four N atoms of the tren unit and is located 0.604 (3) Å out of the trigonal plane described by the three secondary amine N atoms, away from the bridgehead N atom. Edge‐to‐face π–π interactions between the aromatic end groups, and weak interactions between Ag and arene, allow the formation of a pseudo‐cage complex.     

Thermal and light-induced spin-crossover in salts of the heptadentate complex [tris(4-{pyrazol-3-yl}-3-aza-3-butenyl)amine]iron(ii)

The syntheses of [FeL][BF(4)](2).H(2)O, [FeL][ClO(4)](2).H(2)O, [FeL][NO(3)](2).CH(3)NO(2) and [FeL][CF(3)SO(3)](2) (L = tris(4-{pyrazol-3-yl}-3-aza-3-butenyl)amine) are described. The isostructural BF(4)(-) and ClO(4)(-) salts are high-spin between 5-300 K, while the other two compounds are high-spin at room temperature but undergo gradual high-->low spin transitions upon cooling. For [FeL][NO(3)](2) this transition is centred at 139 K and proceeds to near-completeness, while for [FeL][CF(3)SO(3)](2) it is centred at 144 K and only proceeds to 50% conversion. The CF(3)SO(3)(-) salt also undergoes spin-crossover centred at 200 K in (CD(3))(2)CO solution, and exhibits dynamic inversion of its helical ligand conformation. All these compounds except the triflate salt have been crystallographically characterised, and show capped trigonal antiprismatic [6 + 1] coordination geometries. The NO(3)(-) and CF(3)SO(3)(-) salts undergo quantitative conversion to trapped, high-spin excited states upon irradiation with a green laser at 10 K (the LIESST effect; LIESST = Light-Induced Excited Spin State Trapping). The thermal stabilities of their LIESST excited states (T(LIESST) = 80-82 K) resemble those found for iron(ii) complexes of bidentate N-heterocyclic ligands. Hence, the LIESST properties of [FeL](2+) are those of a complex of three rigid bidentate domains linked by a flexible spacer, rather than of a single encapsulating podand.     

Preparations of bis[2-(2-arylethynyl)-3-thienyl]arenes and bis[2-{2-(trimethylsilyl)ethynyl}-3-thienyl]arenes

4,4′-Bis[2-(2-phenylethynyl)-3-thienyl]biphenyl, 4,4′-bis[2-{2-(trimethylsilyl)ethynyl}-3-thienyl]biphenyl and their congeners were prepared and their properties were studied. Extension of π-system through the central benzene ring was suggested by UV-vis spectra. Connection of two 1,4-bis[2-{2-(trimethylsilyl)ethynyl}-3-thienyl]benzene units was exemplified.     

Synthesis of N-[4-(2-naphthyl)]- and N-[4-(2-thienyl)methylaminobenzoyl]-dl-glutamic acids

N-[4-(2-Naphthyl)]-(IIa) and N-[4-(2-thienyl)methylaminobenzoyl]-dl-glutamic acids (IIb) have been synthesized for biological tests by the reaction of the corresponding halogen derivatives with diethyl p-aminobenzoyl-dl-glutamate (III) with subsequent hydrolysis of the esters obtained.