Volume 56, Issue 9

Salts of the 5,5′-azotetrazolate dianion with methylated ammonium and hydrazinium cations were prepared. The compounds were characterized by elemental analysis, vibrational (IR, Raman) and multinuclear NMR spectroscopy ( 1 H, 13 C, 14 N). The crystal structures of the di[ammonium], the bis[dimethylammonium] and the bis[trimethylhydrazinium] 5,5′-azo­ tetrazolate salts were determined. The thermal, shock and friction sensitivities of these com­ pounds were investigated and their explosion products were analysed.

Salts of the 5,5′-azotetrazolate dianion with several different hydrazinium cations were pre­ pared. The compounds were characterized by elemental analysis, vibrational spectroscopy (IR, Raman) and multinuclear NMR spectroscopy ( 1 H, 13 C, 14 N). The crystal structures of the di-tert-butylhydrazinium, the ethylenedihydrazinium, the diguanidinium and the bis-triamino-guanidinium azotetrazolate were determined. The thermal, shock and friction sensitivities of all compounds were investigated and their explosion products were analysed. For the 5,5′-azotetr-azolate dianion the structure was calculated with density functional theory (B3-LYP). An NBO analysis was performed for the 5,5′-azotetrazolate dianion in order to understand the charge distribution of the dianion.

N-Acetyl-L-alanine methylester crystallizes in the orthorhombic space group P2 1 2 1 2 1 with one molecule in the asymmetric unit (a = 7.768(1), b = 9.606(1), c = 10.215(2) Å, Z = 4). The individual molecules are linked into infinite strands by intermolecular hydrogen bonds between the amide hydrogen atom as donor and the acetyl oxygen atom as acceptor. The strands run parallel to the crystallographic b axis. The respective racemate, N-acetyl-DL-alanine methylester, crystallizes in the monoclinic space group P 2 1 /n with three molecules in the asymmetric unit (a = 14.442(3), b = 8.467(2), c = 19.336(5) Å, β = 93.68(1)°, Z = 12). Again, the individual molecules are linked into infinite strands by N-H···O= C acetyl hydrogen bonds which run along the crystallographic a axis. The individual strands are made up of molecules of opposite chirality in a 2:1 ratio. More specifically, one set of strands consists of molecules in the sequence [D, D, L,]∞ while a second set has the sequence [L, L, D]∞ as imposed by the centrosymmetry o f the space group. Thus, although crystals o f N-acetyl-DL-alanine methylester contain equal amounts of the molecules of opposite chirality, the strand formation through intermolecular hydrogen bonds leads to an incom plete resolution of the racemic mixture of molecules within one strand. The reason for the preference of the observed structure o f N-acetyl-DL-alanine methylester over spontaneous resolution is seen in the optimization of hydrogen bonding within one strand versus the overall crystal packing energy. Some principles of the crystallization of achiral molecules, chiral molecules, and racemates are briefly reviewed, as is the phenomenon of spontaneous resolution.

The reactions of 4 N-phenyl-2-[ 1 -(pyrrol-2-yl)methylidene]-hydrazine carbothioamide (4PL 1 ) and 4 N-phenyl-2-[l-(pyrrol-2-yl)ethylidene]-hydrazine carbothioamide (4PL 2 ) with Group 12 metal halides afford complexes of types [M(L) 2 X 2 ] [M = Zn, L = 4PL 1 or 4PL 2 , X = Cl, Br or I; M = Cd, L = 4PL 1 , and X = Cl, or L = 4PL 2 and X = Cl, Br or I] and [M(L)X 2 ] [M = Cd, L = 4PL 1 , X = Br or I; M = Hg, L = 4PL 1 or 4PL 2 , X = Cl, Br or I]. The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR spectroscopy, and, in the case of sufficiently soluble compounds, 1 H, 13 C and, when appropriate, 113 Cd or 199 Hg NMR spectrometry. The structures of [Hg(4PL 1 -H)Br] and [Zn(4PL 2 ) 2 Br 2 ] · 2 EtOH were also studied by single-crystal X-ray diffractometry. In [Hg(4PL 1 -H)Br] crystallized from the mother liquor of its synthesis, 4PL 1 behaves as a monodeprotonated S,N-bidentate ligand. Otherwise, with Hg(II), Zn(II) and Cd(II), 4PL 1 and 4PL 2 both behave as neutral S-monodentate ligands.

The packing motifs of 2-and 3-chloropyridinium chloride can be interpreted in terms of classical hydrogen bonds N + -H···Cl - and non-classical C-H···Cl - " interactions, with halo-gen-halogen contacts playing a subordinate role. In the corresponding bromine derivatives, Br···Br interactions are much more important. Of the dihalo derivatives, 3,5-dichloropyridinium chloride crystallises with classical linear hydrogen bonds of the form N + -H···Cl - , but its chlorine-chlorine interactions are at best weak; the corresponding bromine derivative displays aggregates of bromine atoms and three-centre hydrogen bonds N + -H (···Br - ) 2 .

[FeL(MeOH)Cl] 2 (L = N-(5-methylphenyl)-3-methoxysalicylaldimine) was synthesized and its crystal structure determined, [C 30 H 26 Cl 2 Fe 2 N 2 O 6 ], triclinic, space group P1̄, a = 7.481(2), b = 9.436(2), c = 10.961(2) Å, α= 69.790(10), β= 82.440(10), γ= 83.690(10)°, V=718.1(3) Å 3 , Z = 1. Two identical [FeLCl] fragments, related by an inversion centre, are connected by two bridging O atoms to form a binuclear unit. The iron(III) centers are separated by 3.196(2) Å and weakly antiferromagnetically coupled (J = -10.4(1) cm -1 ), which follows from temperature-dependent magnetic susceptibility measurements in the range 5.1 to 275.6 K. The magnetic moment at 275.6 K is ca. 7.02 B. M., but 0.99 B. M. at 5.1 K. The magnetic susceptibility is at a maximum near 80 K and decreases rapidly as the temperature is lowered to liquid helium temperature.

The ability of the aromatic tetraaldehyde l,2-bis(4-tert-butyl-2,6-diformylphenylsulfanyl)-ethane (1) to function as a precursor in the preparation of binucleating hexaamine-dithiolate ligands has been investigated. Reductive amination of compound 1 with bis(aminoethyl)amine under medium-dilution conditions affords the macrobicyclic hexaamine-dithioether compound L 1 . Deprotection of the [1+2] condensation product gives the corresponding 24-membered hexa-amine-dithiophenol ligand H 2 L 2 . The formulation of L 1 as a macrobicyclic amine-thioether was confirmed by an X-ray crystal structure determination of the tetranuclear nickel(II) complex of L 1 , [{(L 1 )Ni 2 Cl 2 } 2 (μ-Cl) 3 ](BPh 4 ) (2b). The formulation of the doubly deprotonated form (L 2 ) 2- of H 2 L 2 as a 24-membered amine-thiophenolate ligand was confirmed by an X-ray crystal structure determination of the dinuclear cobalt(III) complex, [(L 2 )Co III (μ-OH)](ClO 4 ) 2 · Cl (3). The preparation and the crystal structures of the new compounds are described.

The thermodynamical data of solid Lanthanum Aluminium Bromide LaAl 3 Br 12 have been obtained by determination of the decomposition equilibria from total pressure measurements. For different compositions LaBr 3 /AlBr 3 , the barogram of the binary system LaBr 3 -AlBr 3 was constructed and from this and DTA the melting diagram was determined. The chemical trans­ port of LaBr 3 with AlBr 3 is suggesting the existence of two gaseous complexes LaAl 3 Br 12 and LaAl 2 Br 9 . The data are: ΔH° B (LaAl 3 Br 12 ,f,298) =-587,2 ± 7 kcal/mol, S°(LaAl 3 Br 12 ,f,298) = 179,3 ± 7 cal/K·mol; ΔH°B(LaAl 3 Br 12 ,g,298) =-548,7 ± 5 kcal/mol, S°(LaAl 3 Br 12 ,g,298) = 239,4 ± 6 cal/K·mol; ΔH°B(LaAl 2 Br 9 ,g,298) =-619,7 ± 5,5 kcal/mol, S°(LaAl 2 Br 9 ,g,298) = 212,0 ± 7 cal/K·mol. From solution calorimetric measurements follows the enthalpy of formation of the solid com­plexes: ΔH° B (LaAl 3 Br 12 ,f,298) =-590,9 ± 3 kcal/mol.

The pure ternary phases on the line Sm 2 O 3 -SeO 2 : Sm 2 Se x O 3+2x in thermodynamical equilibri­um have been synthesizied by solid state reactions and characterized by X-ray powder diffrac­tion, IR spectroscopy and DSC measurements. The existence of two new phases Sm 2 Se 1,5 O 6 and Sm 2 Se 4 O 11 was demonstrated besides the known phases Sm 2 Se 3,5 O 10 , Sm 2 Se 3 O 9 and Sm 2 SeO 5 . The thermal decomposition properties of all compounds have been determined by total pressure measurements and the thermodynamical data of the compounds have been derived from their decomposition function and C p -values. The phase diagram and the phase barogram have been estabilished using the results of DSC and total pressure measurements.

The reaction of zinc(II) acetate dihydrate and the tetra-dentate N-Oxo-2-acetylpyridine 4 N-methylthiosemicarbazone (H4MLO) produces the novel complex [Zn(C 9 H 11 N 4 OS) 2 ·H 2 O] (1). The complex crystallizesoin the orthorhombic space group Pbca with a = 15.871(3), b =16.890(3), c = 17.189(3) Å ,V - 4608(1) Å 3 , Z = 8 . The Zn(II) ion is tetra-coordinated via the thiolate sulfur atom and the azomethine nitrogen atom of two deprotonated ligands. In the solid state, 1 is polymerized via hydrogen bonds with a water molecule of crystallization.

Mixed crystals [Cu 0.5 Co 0.5 (H 2 Tea)(SCN)] (1), [Cu 0.5 Co 0.5 (H 2 Tea)Cl] (2) (H 3 Tea = triethanolamine) have been obtained by the open-air reaction of metallic copper with cobalt(II) chloride/cobalt(II) thiocyanate and triethanolamine in non-aqueous solvents, like dmf, dmso, CH 3 OH and CH 3 CN. The simultaneous presence of copper and cobalt in the mixed crystals was unambiguously determined by atomic absorption, EPR and electronic spectroscopy. Details of 1 have been studied structurally, and a preliminary report of the structure of 2 is also given. The mononuclear species 1 and 2 contain crystallographically indistinguishable Cu(II) and Co(II) ions in virtually identical trigonal bipyramidal sites. The molecules are linked together by O-H···O hydrogen bonds to give chains. The values of the temperature independent μ eff of 3.50 and 3.48 μ B for 1 and 2 (in the range of T = 20 - 280 K), respectively, agree with the 1:1 molar ratio of the metals in both samples.

The dilithium diamide reagent obtained from N,N′-di( t butyl)-1,4-diazabutadiene and two equivalents of lithium metal reacts with anhydrous gallium trichloride in tetrahydrofuran / hexane, followed by treatment with metallic potassium, to give the title compound in about 40% yield. Cyclic imides of gallium(III) and gallium(II) are by-products of this process. The structure of Li{[cis-C 2 H 2 (N t Bu) 2 ] 2 Ga} has been determined from single crystals containing one mole equivalent of tetrahydrofuran. The gallium atom is chelated by two diamide ligands. One of the five-membered chelate rings is planar while the second one is folded at its nitrogen atoms. The lithium atom is η 4 -coordinated to the 1,4-diazabutene(2) unit of this ring and further to the oxygen atom of the solvent molecule.

The reactions of tetrathiorhenate(VII) or tetrathiotungstate(VI) with [MCl 2 (C 5 Me 5 )] 2 , M = Rh or Ir, yield the neutral title compounds of which (ReS 4 )[RhCl(C 5 Me 5 )] and (μ- WS 4 )[IrCl(C 5 Me 5 )] 2 could be crystallographically characterized. The molecules contain nearly tetrahedral M′S4 units and rhodium(III) or iridium(III) centers with piano stool geometry. Weak intermolecular (M)Cl- -H(Me) interactions are observed in the crystals. Vibrational and electronic spectra are in agreement with the structures, illustrating p→d charge transfer interactions between the sulfide or chloride donors and the d 0 or d 6 metal acceptor centers, respectively. Oxidation and reduction of the compounds occur completely irreversibly.

Silicon, Silenes Two intramolecularly donor-stabilized silenes, l-(8-dimethylamino-l-naphthyl)-l,2,2-tris-(trimethylsilyl)silene (1), and l-[bis-2 ,6 -(dimethylaminomethyl)phenyl]-l,2 ,2 -tris(trimethyl-silyl)silene 2, were studied by 2 9 Si and C NMR spectroscopy, using polarization transfer techniques in order to determine coupling constants V (2 9 Si,2 9 Si) in = 1,2, 3) and '/ (2 9 Si,l3 C) together with isotope-induced chemical shifts 1 zA12/l3 C(2 9 Si) and Z\2 8 / ~9 Si(C).

The Lewis base adducts of imidovanadium(V) compounds 5a,b undergo chemoselective cyclooligomerization reactions with the kinetically stabilized phosphaalkynes 4a-e to furnish the azatetraphosphaquadricyclanes 6a-f with incorporation of the imido fragment. The reactivity of this novel class of heteropolycyclic compounds has been examined exemplarily for compound 6a. Complexation of one and two phosphorus atoms was achieved by reaction with nonacarbonyldiiron or the tungsten pentacarbonyl-THF complex resulting in the formation of the transition metal compounds 17-20. Reactions of 6a with the sulfonyl azides 21ac furnished the Staudinger products 22a-c. The reaction of 6a with two equivalents of tosyl azide gave a surprising result. No double complexation leading to a symmetrical product was achieved, and compound 23 was obtained instead in which the two phosphorus atoms of one diphosphirane ring are functionalized. Oxidative cleavage of a P/P bond in 6a to furnish product 24 is observed in the reaction of 6a with the Lewis base-free imidovanadium(V) species 15a.

Modifications of the previously reported meth­ods of preparation of racemic pyrazino-methyl-ethylenedithio-tetrathiafulvalene, i.e., 2-(5,6-dihy-dro-5-methyl-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene)-1,3-dithiolo[4,5-b]pyrazine, and their cat­ ion radical salts with linear counter anions are re­ ported. ESR spectra and preliminary X-ray dif­ fraction measurements indicate that the salts crystallize in the τ-phase (tetragonal system).