Volume 70, Issue 12

The tridentate N-donor ligand 2,6-di(2-oxazolyl)pyridine (L) reacts with AgClO 4 and AgPF 6 to yield two new complexes, {[Ag 5 (L) 5 ](ClO 4 ) 5 } n ( 1 ) and {[Ag 5 (L) 5 ](PF 6 ) 5 } n ( 2 ), which have been characterized by single-crystal and powder X-ray diffractions, IR spectroscopy, and elemental and thermogravimetric analyses. Complexes 1 and 2 are isotypic, displaying helical chain structures. The fluorescence properties of 1 and 2 were investigated.

A mixed-valence Cu(I)/Cu(II) coordination polymer, namely, [Cu 2 (L)(1,3-BDC)] n ( 1 ), has been synthesized under hydrothermal conditions (HL = 2-(2-fluorophenyl)-1 H -imidazo[4,5- f ][1,10]phenanthroline and 1,3-H 2 BDC = 1,3-benzenedicarboxylic acid). Its structure has been determined by single crystal X-ray diffraction analysis and powder X-ray diffraction. The crystals are the monoclinic space group P 2 1 / c with a = 10.686(4), b = 17.376(8), c = 11.759(4) Å, β = 92.072(14)°, C 27 H 14 Cu 2 FN 4 O 4 , M r = 604.50, V = 2182.1(15) Å 3 , Z = 4, D calcd. = 1.84 g cm –3 , R = 0.0588 and wR = 0.1202 (all data). In complex 1 , the mixed-valence Cu(I)/Cu(II) atoms are linked by L and 1,3-BDC to give a rare 3D (3,3,4)-connected (4.7.9)(7.8.9)(4.7.8.9 3 ) framework. The temperature-dependent magnetic susceptibility of 1 was investigated in the temperature range of 2–300 K.

The synthesis of a simple fluorescent naphthalimide-based receptor N -allyl-4-iminodi( N -butylacetamide)-1,8-naphthalimide 3 was carried out as a selective picrate (Pic – ) anion probe, and the detecting behavior of this probe was studied by fluorescence spectroscopy. In DMF solution, the interaction of compound 3 with different anions, including Pic – , F – , Cl – , Br – , I – , OH – , Ac – , NO 3 – , ClO 4 – , SCN – , SO 3 2– , SO 4 2– , H 2 PO 4 – , and HPO 4 2– , revealed significant fluorescence quenching only with the Pic – anion. By adding the picrate anions, green-yellow fluorescence emission quenches, which is easily observed by naked eyes under a 365 nm UV light irradiation. This phenomenon is essential for producing a highly selective and sensitive fluorescent probe for picrate anions. The probe can be applied to the quantification of Pic – with a linear range covering from 4.97 × 10 –6 to 6.82 × 10 –5 m and a detection limit of 5.8 × 10 –7 m . Most importantly, probe 3 has a high selectivity for picrate over competitive anions and picrate-containing analytes, which meet the selective requirements for practical application. Thus, the present results would be inspiring findings in the future design of reaction-based fluorescent turn-off probes for the environmentally relevant picrate probe.

The structures of the tricyclo[2.2.1.0 2,6 ]heptaphosphide trisanion, tricyclo[2.2.1.0 2,6 ]heptaphosphane triradical and their carbocyclic analogues have been investigated theoretically at the density functional theory (DFT) (B3LYP/6-31 + G*) level. The existence of negative hyperconjugation in these molecules could be established by natural bond orbital analysis. The weakening of the σ bonds combined with the possibility of the valence-shell expansion at the anionic charge carrying phosphorus atoms in the tricyclo[2.2.1.0 2,6 ]heptaphosphide trisanion induces a degenerate [2,2]sigmatropic rearrangement with a low energy barrier making all the phosphorus atoms equivalent, as detected by 31 P NMR experimentally. This energy barrier is enhanced in the presence of counterions. Its carbocyclic analogue trisanion fails to undergo a [2,2]sigmatropic rearrangement due to the inability of the anionic carbon centres to expand their valence shell. The tricyclo[2.2.1.0 2,6 ]heptaphosphane triradical and its carbocyclic analogue undergo a [2,2]sigmatropic rearrangement, as valence-shell expansion at the carbon atom is not required in this case. A lower activation energy barrier for the [2,2]sigmatropic rearrangement of the tricyclo[2.2.1.0 2,6 ]heptane triradical as compared to that for its phospha-analogue can be rationalised on the basis of the higher ring strain of cyclopropane than triphosphirane.

The l -valinates M (Val) 2 of M = Ni ( 1 ), M = Cu ( 2 ) and M = Zn ( 3 ) are easily obtained as crystalline hydrates. Their structural reinvestigation resulted in a general enhancement of precision for 1 · 2 H 2 O and 2 · H 2 O, in case of the copper complex in the correction of the previously reported space group and in case of the zinc complex 3 in the determination of the structure of a new hydrate 3 · 2 H 2 O.

The reaction of 1-(quinolin-2-ylmethyl)pyridinium ylide with dimethyl acetylenedicarboxylate was investigated. The X-ray crystallographic characterization of the new dimethyl 3-(quinolin-2-yl)indolizine-1,2-dicarboxylate ( 2 ) shows the formation of a five-membered ring between the pyridine ring and the methylene group.

The intermetallic gold compounds RE 4 Mg 3 Au 10 ( RE = La, Ce, Pr) and RE 4 Cd 3 Au 10 ( RE = Y, La–Nd, Sm, Gd–Dy) were obtained from the elements through high-frequency melting in sealed niobium tubes and subsequent annealing in a muffle furnace. The new aurides crystallize with the Ca 4 In 3 Au 10 -type structure. They were characterized through Guinier powder patterns. The structures of Pr 4.46 Cd 2.54 Au 10 and Tb 4.38 Cd 2.62 Au 10 were refined from single crystal X-ray diffractometer data: Cmce , a = 1396.73(6), b = 1009.38(3), c = 1019.51(3) pm, wR 2 = 0.0423, 1281 F 2 values, 47 variables for Pr 4.46 Cd 2.54 Au 10 and a = 1362.68(3), b = 995.52(4), c = 1003.79(3) pm, wR 2 = 0.0381, 1594 F 2 values, F 2 47 variables for Tb 4.38 Cd 2.62 Au 10 . The 8 e sites of both crystals show substantial Cd/Pr respectively Cd/Tb mixing, indicating small homogeneity ranges for all RE 4+ x Mg 3– x Au 10 and RE 4+ x Cd 3– x Au 10 aurides. The gold atoms in these aurides form a pronounced two-dimensional substructure (275–327 pm Au–Au in Pr 4.46 Cd 2.54 Au 10 ) which encages the Mg1/Cd1 (coordination number 8) and RE 2 (coordination number 11) atoms. These blocks are separated by the Mg2/Cd2 and RE 1 atoms with an intergrowth of Mg2/Cd2@Au 8 and RE 1@Au 10 polyhedra. Temperature dependent magnetic susceptibility and specific heat measurements of Tb 4 Cd 3 Au 10 have shown antiferromagnetic ordering at a Néel temperature of 12(1) K.

Manganese(II) biphenyl-4,4′-dicarboxylate, prepared by crystallization of a mixture of biphenyl-4,4′- dicarboxylic acid, manganese(II) chloride, and di(4-pyridyl)acetylene as base in a mixture of dimethylformamide, ethanol and water in a closed vessel at elevated temperatures forms a 3D network of {[Mn(bpdc)(H 2 O) 2 ][Mn(bpdc)(H 2 O)]} containing one five-fold coordinated and one six-fold coordinated Mn metal center (X-ray structure determination). Scanning tunneling microscopic (STM) measurements of manganese biphenyl-4,4′-dicarboxylate adsorbed on highly oriented pyrolytic graphite showed strands, the averaged diameter of which amounts to 18±1 nm, whereas the apparent height is about 0.5±0.02 nm.

New alkaline earth-gold-aluminides were synthesized from the elements in sealed tantalum or quartz ampoules in muffle furnaces at maximum annealing temperatures of 1325 K. The structures were refined from single crystal X-ray diffractometer data. SrAu 3 Al 2 crystallizes in an ordered version of the LT-SrZn 5 structure: Pnma , a = 1315.9(3), b = 549.0(1), c = 684.5(3) pm, wR 2 = 0.0232, 930 F 2 values, 35 variables. SrAu 2.83 Al 2.17 ( a = 1065.0(2), b = 845.0(2), c = 548.1(1) pm, wR 2 = 0.0416, 452 F 2 values, 22 variables) and BaAu 2.89 Al 2.11 ( a = 1096.1(3), b = 835.7(3), c = 554.0(1) pm, wR 2 = 0.0280, 501 F 2 values, 22 variables) both adopt the BaZn 5 type, space group Cmcm with Au/Al mixing on the 4 c site. The gold and aluminum atoms in both types form three-dimensional networks of condensed tetrahedra with the strontium and barium atoms in large cavities. BaAu 7.09 Al 5.91 is a new member of the NaZn 13 type: Fm 3̅ c , a = 1257.6(2) pm, wR 2 = 0.0267, 168 F 2 values, 12 variables. Both the 96 i and 8 b sites show Au/Al mixing. The crystal chemical details are discussed.

The complexes Ph 3 P E AuI ( E = S, Se; 1 , 2 ) were obtained from the reaction of Ph 3 P E AuCl with KI; they are appreciably less stable than their chloro and bromo analogues. The X-ray structures were determined, whereby 1 proved to be contaminated by a small amount of Ph 3 PS·I 2 . Oxidation of 1 and 2 with elemental iodine led to the adducts Ph 3 P E AuI·0.5I 2 ( 3 and 4 ), but X-ray investigation of a crystal initially assumed to be 3 proved it to be a 1:1 mixture of 3 with the adduct Ph 3 PS·1.5I 2 , while in 4 the iodine molecule was severely disordered, which prevented successful refinement of the structure. Decomposition of 4 by loss of gold led to Ph 3 PSeI 2 ·1.5I 2 4a . Complexes Ph 3 P E Au X ( E = S, Se; X = Br, Cl) were oxidized by elemental bromine ( X = Br) or PhICl 2 ( X = Cl) to Ph 3 P E Au X 3 ( 5 , 6 , 9 , 10 ); none of these X-ray structures could be refined satisfactorily because of diffuse scattering phenomena. Further oxidation led to the ionic compounds [Ph 3 P EX ] + [Au X 4 ] – ( X = Br, E = S, Se: 7 , 8 ; X = Cl, E = S, 11 ) or [Ph 3 PSeCl] + 0.5[Au 4 Cl 10 Se 2 ] 2– ( 12 ), containing the novel groupings P– E – X . X-ray structures confirmed the nature of all four of these compounds, which display longer P– E bonds than the gold(I) starting materials and short X···X and/or E···X contacts between cations and anions.

The rare-earth borosilicates RE 3 BSi 2 O 10 ( RE = Pr, Tb) were synthesized under high-temperature conditions of 1600 °C in a radio frequency furnace from praseodymium oxide, terbium oxide, silicon dioxide, silicon nitride, boron trioxide, and boric acid. The structure determinations based on powder diffraction data revealed that both phases RE 3 BSi 2 O 10 ( RE = Pr, Tb) are isotypic to Gd 3 BSi 2 O 10 [L. Chi, H. Chen, X. Lin, H. Zhuang, J. Huang, Jiegou Huaxue 1998 , 17 , 297]. The compounds crystallize in the orthorhombic space group Pbca (no. 61) with eight formula units and the lattice parameters a = 982.9(2), b = 714.2(2), c = 2314.4(4) pm, V = 1.6247(4) nm 3 , R p = 0.0231, and R wp = 0.0354 (all data) for Pr 3 BSi 2 O 10 and a = 960.5(5), b = 692.1(3), c = 2272.4(1) pm, V = 1.5106(2) nm 3 for Tb 3 BSi 2 O 10 . The lattice parameters of Tb 3 BSi 2 O 10 could be determined, but a final refinement of the powder data has not proved satisfactory. The structure of Pr 3 BSi 2 O 10 exhibits eight- (Pr1) and ninefold coordinated rare-earth cations (Pr2 and 3). Layers of ortho-silicate anions [SiO 4 ] 4– and borosilicate anions [BSiO 6 ] 5– are arranged alternatingly along the c axis and the RE cations are located in between.