Band 51, Heft 3

The compounds Co 5 Sn(BO 3 ) 2 O 4 (I) and Co 5 Mn(BO 3 ) 2 O 4 (II) were prepared by using a B 2 O 3 flux technique. Single crystals were investigated by X-ray diffraction and showed orthorhombic symmetry, space group D 2h 9 -Pbam (No. 55), I a = 944.4; b = 1233.8; c = 310.5 pm; Z = 2 and II a = 925.07; b = 1241.67; c = 305.24 pm; Z = 2. Both compounds are isotypic to the mineral Ludwigite. All metal point positions show an octahedral oxygen coordination. Co 2+ and M 4+ (M = Sn or Mn) occupy one point position statistically. Both structures contain isolated, trigonal planar BO 3 units and oxygen atoms that are not coordinated to boron.

Single crystals of the new compound Ba 2 Zn(B 3 O 6 ) 2 were obtained by using a B 2 O 3 flux technique. They crystallize in an as yet unknown structure type. X-ray investigations led to space group C i 1 -P1̄ (Nr.2) with lattice parameters a = 715.5(2), b = 720.5(2), c = 1178.9(4), a = 78.96(2)°, β = 85.45(2)°, γ = 60.12(1)°, Z = 2. The structure is characterized by iso­lated (B 3 O 6 ) 3- -rings and contains two ninefold coordinated Ba-sites. Zn 2+ is tetrahedrally coordinated by oxygen. The relation to the crystal structures of high-temperature BaB 2 O 4 and Ba 2 Ca(B 3 O 6 ) 2 is discussed.

Single crystals of Pb 6 (AsO 4 )[B(AsO 4 ) 4 ] (I) and Pb(BAsO 5 ) (II) were obtained by melting B 2 O 3 , As 2 O 5 and PbO at 800 °C. X-ray investigation led to the space group (I): S 4 1 -P4̄ (Nr. 81) with a = 715.4(1), c = 976.2(3) pm, Z = 1 and (II): C 3 2 -P3 1 (Nr. 144) with a = 712.2(1), c = 693.5(2) pm, Z = 3. While (II) is isotypic to the Stillwellite structure, Pb 6 (AsO 4 )[B(AsO 4 ) 4 ] represents a completely novel type of crystal structure. Boron and arsenic are tetrahedrally coordinated by oxygen. These polyhedra form two kinds of isolated anions: AsO 4 3- and B(AsO 4 ) 4 9- . Lead is eightfold coordinated by oxygen.

Single crystals of the new compound Ba 2 KZn 3 (B 3 O 6 )(B 6 O 13 ) were obtained by using a B 2 O 3 flux technique; they crystallize in an as yet unknown structure type. X-ray investigations led to the space group C i 1 -P1̄ (Nr.2) with lattice parameters a = 705.2(2), b = 712.5(2), c = 1880.3(6), a = 93.43(3)°, β = 90.72(2)°, γ = 119.57(2)°, Z = 2. The structure contains (B 3 O 6 ) 3- -rings and a new discrete (B 6 O 13 ) 8- anion, which is composed of two BO 4 and two B 2 O 5 units. Zn 2+ is tetrahedrally coordinated by oxygen and two out of three tenfold coordinated Ba-sites are statistically occupied by Ba 2+ and K + .

[In(Cl)Pc 2- ] reacts with bis(triphenylphosphine)iminium cyanate ((PNP)OCN) in dichloromethane to yield green-blue b (PNP) cis [In(NCO) 2 Pc 2- ] · CH 2 Cl 2 , which crystallizes in the triclinic space group P1̄ (No. 2) with Z = 2. The two cyanato(N) ligands are in a mutually cis coordination (∠ (N NCO -In -N NCO ) = 84.2(3)°). The In atom is displaced out of the plane of the four N iso atoms towards the two cyanato(N) ligands (d(In-Ct(N iso ) 4 ) = 0.988 Å). The average In-N NC0 and In-N iso bond distances are 2.16(1) and 2.216(8) Å, respectively. The N NCO -In -N NCO moiety deviates by ~ 4° from the staggered conformation relative to the In-(N iso ) 4 sceleton. Though the cyanato(N) ligands are essentially linear, there are different In-N -C angles (164.4(9) and 147.1(8)°) probably due to crystal packing effects. The Pc 2- ligand is distorted in an asymmetrically convex manner. The PNP cation adopts the bent conformation (∠(P-N(K)-P) = 143.5(6)°). The cyclic voltammogram shows three electrode processes, which are assigned to the redox pairs: Pc 3- /Pc 2- (-0.87 V) < In I /In III (-0.63 V) < Pc 2- /Pc - (0.69 V).The UV-VIS-NIR spectra and the vibrational spectra are discussed.

Single crystals of two forms of zinc orthoarsenate (α-Zn 3 (AsO 4 ) 2 (I) and β-Zn 3 (AsO 4 ) 2 (II)) have been prepared by flux techniques. Both compounds crystallize monoclinically, space groups (I): C 2h 5 -P2 1 /c, (II): C 2h 5 -P2 1 /n, with the lattice parameters (I): a = 6.306(2), b = 8.652(2), c =1.321(4) Å, β = 92.25(5) °, Z = 4 and (II): a = 5.281(1), b = 8.494(2), c = 7.726(3) Å, β = 96.39(3)°, Z = 2. α-Zn 3 (AsO 4 ) 2 is isotypic to I-Cu 3 (AsO 4 ) 2 and β-Zn 3 (AsO 4 ) 2 to γ-Zn 3 (PO 4 ) 2 . Similarities and differences of the crystal structures are discussed.

Reactions of mixtures of BaCO 3 , ZnO, Sm 2 O 3 (3:5:1) heated in platinum crucibles up to 1250 °C led to big black single crystals of Ba 4 Sm 4 Zn 3 PtO 15 . The new compound crystallizes with hexagonal symmetry, space group C 6v 4 mc, a = 11.657, c = 6,789 Å , Z = 2. It is isotypic with Ba 6 Nd 2 Al 4 O 15 but shows an ordered Pt 4+ and Zn 2+ distribution over the aluminium positions. The octahedrally coordinated barium sites of the Ba 6 Nd 2 Al 4 O 15 type are occupied by Sm 3+ . In comparison to compounds of the composition Ba 6 Ln 2 M 4 O 15 (M = Al, Fe, Co), Ba 4 Sm 4 Zn 3 PtO 15 is the first example containing different oxidation states at the M 3+ positions.

Reactions of BaCO 3 , ZnO, Lu 2 O 3 and Al 2 O 3 mixtures at temperatures up to 1500 °C led to small and colourless rods of BaLuAlZn 3 O 7 . The new compound crystallizes with hexagonal symmetry, space group C 6v 4 -P6 3 mc, a = 6.273, c =10.161 Å, Z = 2. In spite of small differences in the oxygen content BaLuAlZn 3 O 7 is isotypic to Ba 2 Ln 2 Zn 8 O 13 . The crystal structure shows Zn 2+ with tetrahedral, Lu 3+ with octahedral and Ba 2+ with anticuboctahedral coordination by O 2- . It has been shown that parts of the [Zn 3 AlO 7 ] 5- network are fragments of the ZnO structure. In consequence one oxygen atom is fourfold coordinated by zinc/aluminium. The space group of Ba 2 Ln 2 Zn 8 O 13 must be corrected to C 6v 4 -P6 3 mc.

Cyclopropabenzene 3 reacts with 3,6-bis(trifluoro)-1,2,4,5-tetrazine 4 to afford in high yield the 4a,8a-methanophthalazine 6, the first propellane, containing an electron rich cyclohexadiene system on the one hand and an electron deficient diazadiene system on the other hand. According to the principle of Diels-Alder reactions with inverse electron demand, electron rich dienophiles like ketene acetals, enamines or dimethyl hydrazones react predominantly with the diazadiene system to yield the azo-bridged cycoadducts of type 19 and/or the tricyclic tetrahydropyridazines like 20. In the same fashion several more or less angle strained cycloalkenes cycloadd to the diazadiene of the propellane 6 to give the novel polycyclic azo compounds 34, 36, 38,40, 42 and 44 with exo-configuration of the annulated cycloalkanes. Attack apparently occurs from less hindered face anti to the methano bridge of 6 with high stereo-and site-selectivity. As anticipated the electron deficient dienophiles 1,2,4-triazoline-3,5-dione 45 and the benzoquinone 46 add with different site selectiviy to 6 furnishing the polycyclic pyridazines 47 and 48 resp. again by exclusive anti attack. Treatment of 6 with both an electron rich and an electron deficient dienophile like 49 and 45 resp. affords the heptacyclic anti-anti-bis adduct 51 with analogously high site-and stereoselectivity.

In the reaction of [B 6 H 6 ] 2- with diiodopentane or diiodohexane in dichloromethane μ-pentamethylene-bis-hexahydro-closo-hexaborate, [B 6 H 6 (CH 2 ) 5 B 6 H 6 ] 2- (I), and μ-hexamethylene-bishexahydro-closo-hexaborate, [B 6 H 6 (CH 2 ) 6 B 6 H 6 ] 2- (II), are formed, respectively. The products were separated from excess [B 6 H 6 ] 2- by ion exchange chromatography on diethylaminoethyl cellulose and have been identified and characterized by 11 B, 13 C, 1 H NMR and vibrational spectroscopy.

By reaction of [B 6 H 6 ] 2- with dibromoethane in acetonitrile μ-dimethylene-bis-hexahydro-closo-hexaborate(2-), [B 6 H 6 (CH 2 ) 2 B 6 H 6 ] 2- , is formed. The compound was separated from excess [B 6 H 6 ] 2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of [As(C 6 H 5 ) 4 ] 2 [B 6 H 6 (CH 2 ) 2 B 6 H 6 ]·[(CH 3 ) 2 CO] (I) and [P(C 6 H 5 ) 4 ] 2 [B 6 H 6 (CH 2 ) 2 B 6 H 6 ]·[C 2 H 5 OH] (II) have been determined by single crystal X-ray analysis: I is triclinic, space group P1̄ with a = 10.264(2), b = 13.804(2) and c = 20.242(2) Å, α = 97.857(10)°, β = 92.734( 11)° and γ = 103.024( 13)°; II is monoclinic, space group P2 1 /n with a = 12.742(2), b = 7.532(2) and c = 26.887(3) Å, β = 95.765( 10)°. The 11 B NMR spectrum of this compound reveals the feature of monosubstituted octahedral B 6 cages. The 13 C NMR spectrum exhibits a triplet at 16.20 ppm with 1 J(C,H) = 120.4 Hz. In the 1 H NMR spectrum a singulet at 0.72 ppm of the CH 2 -groups and two singulets at 1.72 and -4.95 ppm of the BH fragments are observed. The IR and Raman spectra exhibit strong CH stretching bands between 2908 and 2789 cm -1 , BH stretching bands between 2463 and 2396 cm -1 , and the BC stretching vibration at 1144 in the IR and at 1150 cm -1 in the Raman spectrum.

Tris(trimethylsilyl)silylmagnesium bromide, (Me 3 Si) 3 SiMgBr, reacts with 2.5-diisopropylbenzaldehyde to give 2,5-diisopropylphenyl-tris(trimethylsilyl)silylmethanol (1). With sodium hydride in THF compound 1 undergoes a rearrangement through 1,3-Si,O-trimethylsilyl migration affording bis(trimethylsilyl)silyl-(2,5-diisopropylphenyl)-trimethylsiloxy-methane (4). The deprotonation of 1 with organolithium reagents in ether leads to the elimination of lithium trimethylsilanolate according to a modified Peterson mechanism resulting in the formation of the transient silene (Me 3 Si) 2 Si=CH(2,5-iPr 2 C 6 H 3 ) (2). Treatment of 1 with an excess of phenyllithium in diethylether at low temperature gives 1,1,1,3,3,3-hexamethyl-2- phenyl-2-(2,5-diisopropylbenzyl)-trisilane (3), formed in a nucleophilic addition of the excess PhLi to the silene intermediate and in the hydrolytic workup. Stochiometric quantities of MeLi in diethylether at -78 °C convert compound 1 into a head-to-head dimer of the silene 1,2,3,8a-tetrahydro-5,8-diisopropyl-1 -(2,5-diisopropylphenyl)-2,2,3,3-tetrakis-(trimethylsilyl)- 2,3-disilanaphthalene (5). Compound 5, presumably the kinetically preferred product of the cyclodimerization of 2, gradually transforms into the thermodynamically stable 3,4-bis(2,5- diisopropylphenyl)-1, 1,2,2-tetrakis(trimethyl-silyl)-1,2-disilacyclobutane (6). The E/Z-isomers of 6 have been characterized by X-ray crystal structural analyses.

Spectroelectrochemistry of 2,5,8,1 1-tetra-tert-butyl-peri-xanthenoxanthene 1 yields the UV/VIS spectra of the corresponding radical cation 1 + and dication 1 2+ . The bathochromic shift for the dication 1 2+ relative to 1 and to the isoelectronic hydrocarbon anthanthrene (2) can be understood by quantum mechanical calculations (ab initio, AM1) of model structures.

Addition of lithium organyls to sterically hindered para-quinols leads to 1,2-or 1,4-adducts. The 1,4-addition prevails, if the 4-substituents in the quinol and the organic group in the lithium organyl are large. Four 1,4-addition products (2-cyclohex-2-en-1-ones) are synthesized and their structures investigated by NMR spectroscopy. The aryl groups at C-4 and C-5 acquire equatorial positions, the alkyl group at C-6 is bisectional. These results are confirmed by X-ray analysis of 2,6-di-tert-butyl-4-hydroxy-4,5-diphenylcyclohex-2-en-1 -one, revealing a twist boat conformation of the cyclohexene ring.

[Co III (salen)(DMF) 2 ] + X - salts [X = PF 6 , ClO 4 ; salen = bis(salicyliden)ethylendiiminato; DMF = dimethylformamide] have been synthesized by electrochemical and chemical (air) oxidation of Co II (salen). Their monomeric structure with two DMF molecules in the axial positions in both the solid state and DMF solution is shown by X-ray crystal structure analysis, thermal analysis, mass spectroscopy, and 1 H and 13 C NMR spectroscopy. The electrochemical reduction of the [Co III (salen)(DMF) 2 ] + cation is investigated by cyclic voltammetry and com­ pared to the oxidation of the neutral Co II (salen). The redox reaction connecting the cobalt(II) and the cobalt(III) species appears to be a quasi-reversible electron transfer. These properties make the [Co III (salen)(DMF) 2 ] + X - salts starting materials for the analysis of the interaction of basic substrates with cobalt(III) species in the context of the biomimetic oxygenation reactions catalyzed by such complexes.

Reaction of a methanolic copper(II) acetate solution with tetrazolyl enol derivatives 2a (HL 2 ) or 2b (HL 3 ) leads to the formation of the corresponding 2D-coordination polymers 4 ( ∞ 2 [CuL 2 2 ]) and 5 ( ∞ 2 [CuL 2 3 ]), respectively. Single-crystal X-ray diffraction of the supramolecular species 4 and 5 established unequivocally the structures of the regioisomeric coordination polymers. On the contrary, reactions of 2c (HL 4 ) with methanolic copper(II) acetate solution and 2b (HL 3 ) with methanolic zinc(II) acetate solution yield mononuclear chelate complexes 11 ([CuL 4 2 ]) and 12 ([ZnL2 3 (MeOH) 2 ]). The structures of 11 and 12 have been established by X-ray structure analysis.

A series of potentially cytotoxic α,β-unsaturated γ -hydroxy-butyrolactones, -lactams and -thiolactones has been synthesized via regioselective hydride reduction of the appropriate maleic acid anhydrides, imides and thioanhydrides. By this means a straightforward access to naturally occurring antibiotic narthigenine 2, its hitherto unknown thio-analogue 5b and higher substituted derivatives and analogues of 2 is presented.

Partial dechlorination takes place if Endosulfane ® is electrolysed in methanol solution at lead cathodes. The products are detected and identified by GC/MS, IR and NMR spectroscopy. The structure of the product 2 is confirmed by an X-ray structural analysis.

2,3-Dihydro-1,4-diazepinium salts could not be aminomethylated with conventional methods, but the hydrochlorides produced with methyleniminium salts the C-Mannich-compounds. The reactivity of the substrate was mainly controlled by electronic effects of the substituents. Aminomethylation of 1,5-diazapentadienium salts occurred only if the conformations caused no steric hindrance of the β-C-atom. Methyl substituted 2,3-dihydro-1,4-diazepinium salts reacted with 1,3,5 triazine to pyrimidine anellated derivatives.

The title compound was prepared from the cor­responding “ordinary” oxolactone bridged biaryl using Lawesson’s reagent. It crystallizes from dichloromethane / petroleum ether in the mono­clinic system, space group P2 1 /a; a = 1115.7(2),b = 1383.9(2), c = 1042.0(1) pm and β = 106.67(1)°.

[Mn (n- Bu)(NPEt 3 )] 4 has been prepared by the reaction of [MnBr(NPEt 3 )] 4 with n-butyllithium in boiling pentane. The pyrophoric compound forms red, moisture sensitive crystals, which were characterized by IR spectroscopy and by a crystal structure determination (tetragonal, space group 14 1 /a, Z = 4, structure solution with 699 observed unique reflections, R = 0.054. Lattice dimensions at -50 °C:a = b = 2177.4(3) pm, c = 1147.1(2) pm). [Mn (n-Bu)(NPEt 3 )] 4 forms a nearly perfect Mn 4 N 4 hetero cubane framework with μ 3 -N bridges of the NPEt 3 - groups and σ-bonded n-butyl groups with Mn - C distances of 216.8 pm. The n-butyl groups and two of the ethyl groups are disordered.

A chiral ferrocene (Cp E 2 Fe) was synthesized by reaction of Cp E Li with FeCl 2 (THF) 1.5 The cyclopentadienyl ligand Cp E contains a dimethylamino group that is separated from the Cp backbone by two stereogenic carbon centres. Reaction of Cp E 2 Fe with excess Mel affords the ammonium salt Cp E 2 Fe.2MeI. Its solid state structure was determined by X-ray diffraction methods.

The crystal structure of β-CsIO 4 , the room-temperature modification of cesium periodate, was determined as orthorhombic, space group Pnma, with a = 5.8644(5), b = 6.0326(4), c = 14.379(1) A and Z = 4. The structure was refined to R 1 = 0.0309, wR 2 = 0.0701 for 425 absorption-corrected reflections. β-CsIO 4 is isostructural with β-CsReO 4 . The structure comprises isolated IO 4 tetrahedra, linked together by Cs ions. The average I-O dis­tance was found to be 1.747 Å .

The scheelitetype structure of potassium perio­date, KIO 4 , has been confirmed and refined from single-crystal X-ray data at two temperatures. The compound crystallizes tetragonally, space group I4 1 /a, with a = 5.726(1), c = 12.607(4) Å at 297(1) K, and a = 5.704(3), c = 12.478(8) Å at 150(1) K, respectively. Except for a significant decrease in the anisotropic displacement factors, the changes in the structural parameters at low temperature are rather small.

Single crystals of (Cu,Mn) 3.66 Mo 3 O 12 have been prepared in sealed copper tubes. X-ray investiga­tions lead to orthorhombic symmetry, space group D 2h 16 -Pnma, a = 5.1541(9), b = 10.788(2), c = 18.114(3)) Å , Z = 4. (Cu,Mn) 3.66 Mo 3 O 12 is iso­typic to NaCo 2.31 Mo 3 O 12 and (Cu,Co) 3.75 Mo 3 O 12 with split positions for two of the metals.

Single crystals of (Cu,Mn)UMo 3 O 12 have been prepared in sealed copper tubes. X-ray investigations lead to hexagonal symmetry, space group C 6h 2 -P6 3 /m a = 9.7895 (13), c = 6.202(1) Å , z = 2. (Cu,Mn)UMo 3 O 12 is isotypic to CdThMo 3 O 12 . Calculations of the Coulomb terms of lattice energy with respect to different oxidation states of copper, molybdenum and uranium and the previously described pair of isotypic compounds of CdThMo 3 O 12 to Na 2 ThRe 6 O 24 are discussed.

Ba 6 Pr 2 Co 4 O 15 (I) and Ba 5 SrPr 2 Co 4 O 15 (II) have been prepared by high temperature CO 2 -LASER techniques. Both compounds crystallize with hexagonal symmetry, space group C 6v 4 P6 3 mc, (I): a = 11.814(1), c = 7.100(2) Å ; (II): a = 11.646(1), c = 6.8602 Å , Z = 2. It is remarkable that the strongly reducing Pr 3+ can coexist with the more oxidizing Co 3+ .