No abstract

The lanthanum(III) and dysprosium(III) complexes of triethylenetetramine-N, N, N′, N″, N‴, N‴-hexaacetic acid (H6ttha) were prepared and isolated as guanidinium salts:[C(NH2)3]2[La(Httha)] · 3 H2O and [C(NH2)3]2[Dy(Httha)] · 5 H2O. The X-ray crystal structure of both complexes was determined: In the La(III) complex (space group P1̄) all donor atoms (N4O6) are coordinated. The coordination number 10 is realized in a bicapped square antiprism (SAPRS-10). The bond length La to O of the protonated carboxylic group is ca. 0.3 Å longer than the other five La-O distances. The Dy(III) complex (space group P1̄) exhibits coordination number 9 in a monocapped square antiprism (SAPRS-9). The protonated carboxylic group is not coordinated.

The prolonged UV-photolysis of aqueous solutions containing [Mo(7)O(24)](6-) and C(2)H(5)CO(2)H (as electron donor) at pH 3.9-4.1 generates the carboxylate-coordinated {Mo(132)} Keplerate (1a) isolated as a formamidinium/ammonium-mixed salt, [HC(NH(2))(2)](26)(NH(4))(28)[Mo(V)(60)Mo(VI)(72)O(372)(H(2)O)(48)(C(2)H(5)CO(2))(36)((i)C(3)H(7)CO(2))(6)]·16H(2)O (1), through the Mo-blue intermediate (2). The coordination of 2 to La(3+) gives rise to the formation of the chain structure of the C(2)-symmetric {Mo(96)La(8)} eggshell rings, formulated by H(22)[Mo(V)(20)Mo(VI)(76)O(301)(H(2)O)(29){La(H(2)O)(6)}(2)]{La(H(2)O)(5)}(6)]·54.5H(2)O (3). The eggshell-ring geometry results from the insertion of [Mo(VI)(2)O(7)(H(2)O)](2-) (spacer) into the equator outer ring of the wheel-shaped Mo-blue, and 10 {(Mo(VI))(Mo(VI)(5))} pentagonal subunits alternately above and below the equator outer ring are connected by eight La(3+) and two {Mo(VI)(2)} linkers within two inner rings. The neighboring eggshell rings are linked through two Mo-O-Mo bonds formed by dehydrative condensation between the {Mo(VI)(2)} linkers to result in the chain structure. Together with the results of the elemental analysis and IR, electronic absorption, (13)C NMR, and ESI-MS spectra for 2, the ring profile analysis of 3 let us identify 2 with a carbolylate-coordinated Mo-blue ring of high nuclearity. The Mo(VI)→Mo(V) photoreductive change of 2 to the 60-electron reduced Keplerate in the presence of C(2)H(5)CO(2)H involves both degradation of the outer ring and splitting of the binuclear linkers, which leads to the formation of [(Mo(VI))Mo(VI)(5)O(21)(H(2)O)(4)(carboxylate)](7-) pentagonal subunits and [Mo(V)(2)O(4)(carboxylate)](+)/[Mo(V)O(2)(carboxylate)(1/2)](0.5+)-mixed linkers for 1.

UV irradiation (corresponding to the O 3Mo ligand-tometal charge-transfer photoexcitation) of isopolyoxomolybdates in aqueous solutions containing electron donors (such as alkylammonium cations, alcohols, and aliphatic carboxylates) results in formation of high-nuclearity mixed-valence species as a result of reduction self-assembly processes based on the dehydrative condensation at [Mo V O 5 (OH)] sites produced photochemically in the polyoxomolybdate lattice: [1,2] [Mo 7 O 24 ] 6À and b-[Mo 8 O 26 ] 4À , which are dominant species at pH levels of 5.4 and 3.3 respectively, are converted into [Mo 14 O 46 ] 10À ({Mo 14 }) [(Mo V Mo VI 6 O 23 ) 2 ] 10À and [H 14 -Mo 37 O 112 ] 12À {[H 10 Mo V 12 O 40 (Mo VI O 2 ) 3 ][H 2 Mo V 6 Mo VI 5 O 33 ] 2 } 12À , respectively. In our extension of the solution photolysis of isopolyoxomolybdates to [Mo 36 O 112 (H 2 O) 16 ] 8À ({Mo 36 }), which is the dominant species at pH 1 ± 2 and higher-Mo concentrations (! 10 À2 m), we found the photochemical formation of a variety of car-tire-shaped giant molybdenum blues. These were also formed by thermal reduction [3±8] of Na 2 MoO 4 with reducing agents such as iron, ascorbic acid, NH 2 OH ¥ HCl, N 2 H 4 ¥ H 2 SO 4 , and Na 2 S 2 O 4 under strongly acidic conditions (pH % 1). The structure of {Mo 36 } consists of a centrosymmetric arrangement of two {Mo 18 } subunits, each of which is viewed as a Mo 7 O 24 group encircled by edge-and corner-shared MoO 6 octahedra ( Figure 1). [9] We describe here a diamagnetic blue 28-electron reduced species ({Mo 142 } 1 a) produced photochemically through the degradative self-assembly of {Mo 36 } and discuss size and shape for the ring clusters derived from {Mo 36 } on the basis of the successive two-electron reduction dehydrative ± condensation processes similar to the reductive dimerization of [Mo 7 O 24 ] 6À to {Mo 14 }. [1] [Mo V 28 Mo VI 114 O 432 H 28 (H 2 O) 58 ] 12À 1 a The title anion (Figure 2 a) has been isolated as [NH 3 iPr] salt 1 [10±12] the structure of which is quite similar to that reported for Na 26 [Mo V 28 [NH 3 iPr] 10 H 2 [Mo V 28 Mo VI 114 O 404 (OH) 28 (H 2 O) 58 ] ¥ 90 H 2 O 1 3.27 mm À1 ; T 98 K, 2q max 548. Data were collected on a Mercury CCD area detector coupled with a Rigaku AFC-8S diffractometer with graphite-monochromated Mo Ka radiation (0.7107 ä) using CrystalClear (Rigaku Co.). Total reflections collected 30 371. Data were corrected for Lorentz and polarization effects. An empirical absorption correction was applied by using REQABA (min./max. transmission: 0.61/ 1.01). The structures were solved on a Silicon Graphics O2 computer system using teXsan, version 1.11 (Molecular Structure Co.). The initial position of rhenium atoms were determined by direct methods and other atoms were located using Fourier and difference Fourier techniques. Re, Sb, and Se atoms were refined anisotropically. Other non-hydrogen atoms were refined isotropically.With the exception of hydrogen atoms of crystal solvents, all hydrogen atoms were located at the calculated positions. One tolyl ...

Professor Kurt Dehnicke zum 70. Geburtstag gewidmet Inhaltsu È bersicht. Es wurden die Kristallstrukturen der 1,3-Diketone 2,4-Dioxo-4-ferrocenyl-butansa È ureethylester (1) und Ferrocen-1,1'-bis(2,4-dioxobutansa È ureethylester) (2) bestimmt. Durch Umsetzung von 1 mit Cu(ac) 2´H2 O in THF wurde der Kupfer(II)-Komplex Aqua-bis(3-ethoxycarbonyl-1-ferrocenyl-propan-1,3-dionato)-kupfer(II) (1 a) erhalten, der ebenfalls strukturell charakterisiert werden konnte. Des-weiteren wurden die Strukturen der Enaminoketone 2,2'-(1,4-Phenylendiamino)-bis(4-ferrocenyl-4-oxo-but-2-ensa È ureethylester) (3) und Ferrocen-1,1'-bis(4-oxo-2-phenylaminobut-2-ensa È ureethylester) (4) ro È ntgenographisch bestimmt. Erga È nzt wurden die strukturanalytischen Daten durch elektrochemische Untersuchungen.Abstract. The crystal structures of the 1,3-diketones 2,4-dioxo-4-ferrocenyl-butanoic acid ethylester (1) und ferrocene-1,1'-bis(2,4-dioxo-butanoic acid ethylester) (2) have been determined. Through conversion of 1 by Cu(ac) 2´H2 O in THF the copper(II) complex aqua-bis(3-ethoxycarbonyl-1-ferrocenyl-propane-1,3-dionato) copper(II) (1 a) has been obtained, which is structurally characterized too. The structures of the enaminoketones 2,2'-(1,4-phenylenediamino)-bis(4-ferroce-nyl-4-oxo-but-2-enoic acid ethylester) (3) and ferrocene-1,1'bis(4-oxo-2-phenylamino-but-2-enoic acid ethylester) (4) have been determined by X-ray analysis as well. Electrochemical studies completed the structural investigations.