1- and 2-Tetrazolylacetonitrile as Versatile Ligands for Laser Ignitable Energetic Coordination Compounds

1- and 2-Tetrazolylacetonitrile (1- and 2-TAN) have been synthesized by the reaction of chloroacetonitrile with 1H-Tetrazole under basic conditions. They further were reacted with sodium azide in the presence of zinc(II) chloride to form 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT). The nitrogen-rich compounds have been applied as ligands for Energetic Coordination Compounds (ECCs) and show interesting coordinative behavior due to different bridging modes. The structural variability of the compounds has been proved by low-temperature X-ray analysis. The ECCs were analyzed for their sensitivities to provide information about the safety of handling and their capability to serve as primary explosives in detonator setups to replace the commonly used lead styphnate and azide. All colored ECCs were evaluated for their ignitability by a laser diode in translucent polycarbonate primer caps. In addition, the spin-crossover characteristics of [Fe(1-TAN)6](ClO4)2 were highlighted by the measurement of the temperature-dependent susceptibility curve.

“Green” PBX Formulations Based on High Explosives (RDX and HMX) and Water-Soluble pH-Sensitive Polymeric Binders

The increasingly harsher and more complex international and European environmental legislation drives the current development of “greener” energetics materials and munitions. The aerospace and defense industries rely on extensive research in the formulation and scale-up production of polymer-bonded explosives (PBX). In this context, this paper aims to present a versatile method for obtaining “green” PBX formulations based on two high explosives (hexogen (RDX) and octogen (HMX)) and acrylic acid—ethyl acrylate copolymeric binders. This study developed an innovative “eco-friendly” technology for coating the RDX and HMX crystals, allowing straightforward and safer manufacture of PBX, avoiding the use of traditional organic solvents. At the same time, these polymeric binders are soluble in water at a slightly alkaline pH and insoluble at acidic or neutral pH, thus ensuring a safer manipulation of the energetic materials during their entire life cycle and a facile recovery of the explosive in its original shape and morphology in demilitarization. The PBX formulations were characterized via specific analytical tools to evaluate the influence of their composition on the safety and performance characteristics: scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), alkaline pH solubility tests, differential thermal analysis (DTA), impact sensitivity test (BAM Fall Hammer Test), friction sensitivity test (BAM Friction Test), electrostatic sensitivity test (ESD), vacuum stability test, small scale shock reactivity test (SSRT), detonation velocity test. The “green” PBX formulations obtained through a simple and innovative coating method, based on the polymeric binders’ adjustable water solubility, demonstrated remarkable energetic performances and a facile recovery of the explosive crystals by the dissolution of the polymeric binder at pH 11 and 30 °C.

Synthese und spektroskopische Charakterisierung neuer Bis(thiolato)- und Endithiolato-bis(η5-cyclopentadienyl)hafnium(IV)-Komplexe / Synthesis and Spectroscopic Characterisation of New Bis(thiolato)- and Endithiolato-bis(η5-cyclopentadienyl)hafnium(IV) Complexes

The hafnocene thiophenolates Cp2Hf(SC6H4R)2 (Cp = η5-C5Hs; R = H, o-Me,p-Me, p-NH2) and cis- 1.2-endithiolates Cp2Hf(S2C6H4), Cp2Hf(S2C6H3Me-4), and Cp2Hf{S2C2(CN)2} were prepared by reaction of Cp2HfCl2 with equivalent amounts of the appropriate lithium thiolates or endithiolates, or with Na2S2C2(CN)2. respectively. From variable temperature 1H NMR studies of the endithiolate complexes with aromatic ligands a folded (“envelope”) conformation of the five-membered chelate rings, undergoing rapid inversion at room temperature, can be derived.

Methylbis(2,6-dichIorthiophenoIato)bismut(III) — Synthese, fungizide und bakterizide Aktivität/ Methylbis(2,6-dichlorothiophenolato)bism uth(III) — Synthesis, Fungicidal and Bactericidal Activity

The methylbis(thiophenolato)bismuth(III) derivative CH3Bi(SCAH3Cl2-2.6)2 was prepared by reaction of CH3BiBr2 with equivalent amounts of the appropriate lithium thiolate. The new Bi organyl was characterized by elemental analysis, 1H NMR. IR . and mass spectroscopy. The biological activity against bacteria, yeasts, and moulds was investigated.

Synthese und spektroskopische Charakterisierung neuer Mono(cyclopentadienyl)titan(IV)thiolat-Komplexe des Typs CpTi(SR)n(Cl)3-n mit n = 1, 2, 3 / Synthesis and Spectroscopic Characterization of New Mono(cyclopentadienyl)titanium(IV) Thiolate Complexes of the Type CpTi(SR)n(Cl)3-n n =1,2,3

The mono(cyclopentadienyl)titan(IV)thiolat-Komplexe des Typs CpTi(SR)"(Cl) 3 _ n mit n = 1, 2, 3 Synthesis and Spectroscopic Characterization of New Mono(cyclopentadienyl)titanium(IV) Thiolate Complexes of the Type CpTi(SR)"(Cl) 3 _", n =1,2,3 Cyclopentadienyl-dichloro-thiolato-titanium(IV) Complexes, Cyclopentadienyl-chloro-bis(thiolato)-titanium(IV) Complexes, Cyclopentadienyl-tris(thiolato)-titanium(IV) Complexes The mono(cyclopentadienyl)titanium(IV) derivatives CpTi(SR)Cl-> (Cp = ?7 5 -C 5 H 5 ; R = QF S , C 6 H 4 Cl-p, C 6 H 4 Br-p, C6H4CH3-O, C 6 H 4 CH 3 -p, C 6 H", C,H,)\ Cp'Ti(SR)Cl 2 (Cp' = >7 5 -C 5 H 4 CH 3 ; R = C 6 H 5 , C 6 H 4 C1 -p, C 6 H 4 CH 3 -o, C 6 H 4 CH 3 -/>), CpTi(SR) 2 Cl (R = C 6 H 5), Cp'Ti(l,2-S 2 C 6 H 3 CH 3 -4)Cl, and CpTi(SR) 3 (R = C 6 H 5) were prepared by reaction of CpTiCl 3 or Cp'TiCl 3 with equivalent amounts of the appropriate lithium thiolates, or with the free thiol and triethylamine, respectively. The new thiolate complexes were characterized by 'H NMR and mass spectroscopy.

Synthese und Konformationsstudien ringsubstituierter Titanocen-Dithiolen-Chelate / Synthesis and Conform ational Studies of Ring-Substituted Titanocene Dithiolene Chelates

The titanocene dithiolenato chelates Cp′2Ti(S2C6H3CH3-4) and CpCp′Ti(S2C6H3CH3-4) (Cp = η5-C5H5, Cp′ = η5-C5H4CH3) were prepared by reaction o f Cp′2TiCl2 or CpCp′TiCl2 with equiva­lent amounts of 1,2 -(LiS)2C6H3CH3-4. The structure and the conform ational mobility of the η5-bonded and of the chelating ligands of the dithiolenato complexes are discussed on the basis of their temperature-dependent 1H NMR spectra. The mass spectra show metastable transitions for the fragmentation processes.

Synthese und spektroskopische Charakterisierung von Metallocen-chloro-selenophenolaten / Synthesis and Spectroscopic Characterization of Metallocene Chloro Selenophenolates

Bis(/75-cyclopentadienyl)-chloro-selenophenolatotitanium (IV), Bis(?75-cyclopentadienyl)-chloro-selenophenolatozirconium (IV), Bis(//5-cyclopentadienyl)-chloro-selenophenolatohafnium (IV), Bis(^5-cyclopentadienyl)-chloro-selenophenolatotungsten(IV), Mass Spectra The metallocene chloro selenophenolates C p;M Cl(SeChH 5) (Cp = ^5-C5H 5; M = Ti, Z r, Hf, W) were prepared by reaction of Cp2MCl2 with equivalent am ounts of LiSeC6H 5, obtained from phenylselenol and «-butyllithium, and were characterized by 'H NM R, IR and MS data. The fragmentation behaviour of the Ti and W derivatives is elucidated by observing m etastable transi­ tions in the mass spectra.

Antitumor activity of ionic niobocene and molybdenocene complexes in high oxidation states

Four air-stable niobocene complexes [(C5H5)2NbCl2]+X- with X = BF4, AsF6, SbF6, SO3CF3 and the molybdenocene derivative [(C5H5)2MoCl2]2+[SbF6]2- were investigated for antitumor properties against Ehrlich ascites tumor in female CF1 mice. All compounds are new, salt-like complexes containing a cationic metallocene moiety, where the early transition metals niobium and molybdenum in the high oxidation states +5 and +6 function as central atoms. The niobocene complexes containing tetrafluoroborate (BF4-) or trifluoromethanesulfonate (CF3SO3-) as anions only induced a maximal cure rate of 50% and led to increases in life span of 182% and 178% following application of optimal doses. The other two niobocene compounds with hexafluoroarsenate (AsF6-) and hexafluoroantimonate (SbF6-) as anions and the molybdenocene derivative [(C5H5)2MoCl2]2+[SbF6]2- effected a maximal cure rate of 100% and increases in life span of 346%, 376%, and 332%, respectively, determined on the key date, i.e., on day 90 after transplantation. On applying the niobocene hexafluoroantimonate complex [(C5H5)2NbCl2] +[SbF6]-, the optimal dose range with a cure rate of 100% was rather broad and extended from 20 mg/kg to 40 mg/kg. Correspondingly, the value of the therapeutic index (TI) was high and amounted to 7.2. In the case of the niobocene hexafluoroarsenate and the molybdenocene hexafluoroantimonate complexes, the TI value decreased to 5.3 and 2.6 respectively. Neither impairments of the general condition nor any conspicuous symptoms could be detected after application of therapeutic doses of the five compounds investigated. Compared to the neutral niobocene dichloro complex [(C5H5)2NbCl2], the therapeutic range of the ionic niobocene derivative [(C5H5)2NbCl2]+[SbF6]- was broadened, the TI value markedly elevated from 2.9 to 7.2, and the toxic symptoms were impressively reduced. The niobocene hexafluoroantimonate complex was the most effective compound investigated in the present study.

Ionic rhenocene derivatives with antitumor activity

The antitumor activity of the three air-stable bis(cyclopentadienyl)rhenium derivatives [(C5H5)2-ReCl2]+Cl-,[(C5H5)2ReCl2]+[AsF6]- , and [(C5H5)2-ReCl2]+[SbF6]- was tested against Ehrlich ascites tumor in female CF1 mice. All three compounds contain the group-7 transition metal rhenium in the +5 oxidation state as their central metal atom. They are ionic, salt-like complexes that are composed of the cationic [(C5H5)2ReCl2]+ moiety and one of the negatively charged counterions Cl-, AsF6-, or SbF6-. Both the chloro and the hexafluoroarsenate complexes induced a maximal cure rate of 100% when given either in a dose range of 120-160 mg/kg (rhenocene trichloride) or at a single dose of 180 mg/kg (hexafluoroarsenate derivative). The hexafluoroantimonate complex effected a maximal cure rate of only 50% at 60 mg/kg. For the two former compounds, the values for the therapeutic index (TI) amounted to 1.7 and 2.1, respectively. No impairment of the general condition or pathologic symptoms in the viscera could be detected by observation of the animals during the days following treatment with therapeutic doses or by autopsy of the surviving animals on the key date (day 90). The rhenocene derivatives investigated in the present study represent a new class of antitumor metallocene compounds as well as the first rhenium(V) complexes exerting cytostatic activity.

Ionic titanocene complexes: a new type of antitumor agent

Five ionic cyclopentadienyltitanium (IV) derivatives were investigated for their activity against fluid Ehrlich ascites tumor. Four compounds were built up by the intact bis(cyclopentadienyl)titanium(IV) ("titanocene") unit, forming the cationic moiety together with two covalently bound ligands, with certain anions being bonded via electrostatic forces: the acetonitrile complex [(C5H5)2TiCl(NCCH3)]+[FeC14]- (I), the 2'2'-bipyridyl derivative [(C5H5)2Ti(bipy)]2+[CF3SO3]2 (II), the o-phenanthroline complex [(C5H5)2Ti(phen)]2+[CF3SO3]2 (III), and the N-methyl-o-aminothiophenolate derivative [(C5H5)2Ti[o-S(NACH3)C6H4]]+I- (IV). Another ionic cyclopentadienyltitanium derivative investigated was the five-coordinate bis(dithiolene) chelate (C5H5)Ti(1,2,4-S2C6H3CH3)2]-N(C2H5)4)+ (V), the cyclopentadienyltitanium moiety representing the anionic part of the complex salt. All complexes were ionic, salt-like compounds, distinguished by good water solubility. Whereas complexes I, III, and V, given at optimal dose levels, effected maximal cure rates of only 70%-80%, all animals were cured after receiving complexes II and IV at dose ranges of 200-220 and 240-300 mg/kg, respectively. The antitumor activity of complex I was confirmed against solid experimental tumor systems B16 melanoma, colon 38 carcinoma, and Lewis lung carcinosarcoma. Because of their improved solubility in water and pronounced antitumor activity (especially that of II and IV against fluid Ehrlich ascites tumor), ionic cyclopentadienyl titanium complexes are considered to be an interesting new type of antitumor agent.

Antitumor activity of an ionic titanocene tetrachloroferrate derivative against some solid experimental tumors

The metallocene complex bis(cyclopentadienyl)acetonitrilechlorotitanium(IV) tetrachloroferrate(III) [(C5H5)2Ti(Cl)NCCH3]+[FeCl4]- was investigated for antitumor properties against three solid experimental animal tumors (B16 melanoma, colon 38 adenocarcinoma, Lewis lung carcinosarcoma). The growth of all three tumors was inhibited significantly by the titanocene complex. Colon 38 carcinoma and Lewis lung carcinoma revealed to be more sensitive to the titanocene tetrachloroferrate derivative than solid B16 melanoma, whereby the growth development of the aforementioned tumors was suppressed by 70-76% of control tumor size to T/C ratios amounting to 24-30%. Bis(cyclopentadienyl)acetonitrilechlorotitanium(IV) tetrachloroferrate(III) is representative of ionic titanocene complexes which are generally distinguished by improved water solubility in comparison to neutral metallocene compounds.

Tumor inhibition by ferricenium complexes. Activity against some solid experimental tumors

In the present study, the antitumor activity of some water-soluble ferricenium complexes [(C5H5)2Fe]+ X- (I, X- = [FeCl4]-; II, X- = 1/2[Cl3FeOFeCl3]2-; III, X- = [2,4,6-(NO2)3C6H2O]-; IV, X- = [CCl3COO]- 2CCl3COOH) was investigated against the solid, subcutanteously growing tumors sarcoma 180, B16 melanoma and colon 38 adenocarcinoma. Whereas, in the case of solid sarcoma 180, only marginal antitumor activity was observed for I-IV, the compounds effected growth inhibitions of solid B16 melanoma and colon 38 carcinoma by 35-60% and 50-73%, respectively, resulting in T/C ratios of 40-65% and 27-50%. In most tests, ferricenium trichloroacetate IV, followed by ferricenium mu-oxo-bis(trichloroferrate) II, were characterized by best antitumor properties against the tumor models investigated.

Biological activity of organometallic bismuth compounds

The chemical aspects of organometallic bismuth(III) compounds are discussed with respect to the stability of the metal-carbon sigma bond, their low dipole moments, and the limited solubility of these complexes in hydrophilic solvents. A new Bi heterocycle, which is of potential interest in terms of stability and solution behaviour, was shown to exist as an intermediate under the conditions in the mass spectrometer. Although generally bismuth organic compounds are extremely toxic, in the 1970s they became important as biocides and this is still being investigated. They have also been discussed as irritation causing chemical warfare agents. While their application in chemotherapy never became very widespread because antibiotics were discovered, in the last few years the antitumor activity of some derivatives has been reported.

Tumor inhibition by titanocene complexes: activity against sarcoma 180

The antitumor activity of various titanocene derivatives was examined against ascitic and solid, subcutaneously growing sarcoma 180. The complexes investigated were two dihalide compounds, (C5H5)2TiCl2 (I) and (C5H5)2TiBr2 (II), two carboxylato complexes, (C5H5)2Ti (cis-OOCCH = CHCOOH)2(III) and (C5H5)2Ti(OOCCCl3)2(IV), and the p-aminothiophenolate hydrochloride (C5H5)2Ti(p-SC6H4NH3+Cl-)2(V). Against ascitic sarcoma 180, best results were obtained for I; an injection of 50 mg/kg resulted in the survival of 40-50% of the animals (ILS, 161-184%). A similar result was recorded for cis-diamminedichloroplatinum(II), whereas the compounds II-IV induced a maximum cure rate of 20% (ILS, 95-139%). Against solid sarcoma 180, triple injections of I-V caused reduction of mean tumor weight to 23-53% of control values, the dichloro complex I exhibiting most pronounced activity. These results clearly underline antitumor potency for titanocene complexes (C5H5)2TiX2 modified at the acido ligand X.