Indium(III) complexes containing bithiazole derivatives,chloride, methanol,and dimethyl sulfoxide: X‐ray studies,spectroscopic characterization,and thermal analyses

[In(dm4bt)Cl₃(MeOH)]?·?0.5dm4bt (1) (dm4bt is 2,2′‐dimethyl‐4,4′‐bithiazole) and [In(4bt)Cl₃(MeOH)] (2) (4bt is 4,4′‐bithiazole) were prepared from the reaction of 4,4′‐bithiazole and 2,2′‐dimethyl‐4,4′‐bithiazole with InCl₃?·?4H₂O in methanol, respectively. [In(4bt)Cl₃(DMSO)] (3) was also prepared from recrystallization of 2 in DMSO. These complexes were characterized by IR, UV‐Vis, ¹H NMR, ¹³C{¹H} NMR, and luminescence spectroscopy and their structures were studied by single‐crystal X‐ray crystallography. The thermal stabilities of 1 and 3 were studied by thermogravimetric and differential thermal analyses.     

Spectroscopic,Thermal, and Structural Studies of Two New Co‐Crystals of [4,4′‐Bithiazole]‐2,2′‐diamine

Two new 2 : 1 co‐crystals based on [4,4′‐bithiazole]‐2,2′‐diamine (=2,2′‐diamino‐4,4′‐bithiazole (DABTZ)) with 2,2′‐bipyridine (bipy) and benzo‐18‐crown‐6 (bk) were synthesized by slow‐evaporation method in MeOH. These co‐crystals were characterized by means of elemental analysis, and IR, and ¹H‐ and ¹³C‐NMR spectroscopy. Also, thermal analyses under air atmosphere and X‐ray crystallography have been performed on these structures. X‐Ray single‐crystal analyses revealed that these networks contain large vacant voids. These structures, [(DABTZ)₂(bipy)] and [(DABTZ)₂(bk)(MeOH)], crystallized in monoclinic and triclinic forms with space groups of P2₁/c and P , respectively. The self‐assembly of these compounds in the solid state is likely caused by both H‐bonding and π? π stacking.     

Synthesis and Photovoltaic Properties of Cyclopentadithiophene‐Based Low‐Bandgap Copolymers That Contain Electron‐Withdrawing Thiazole Derivatives

We have synthesized four types of cyclopentadithiophene (CDT)‐based low‐bandgap copolymers, poly[{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl}‐alt‐(2,2′‐bithiazole‐5,5′‐diyl)] ( PehCDT‐BT ), poly[(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(2,2′‐bithiazole‐5,5′‐diyl)] ( PocCDT‐BT ), poly[{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl}‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole‐5,5′‐diyl}] ( PehCDT‐TZ ), and poly[(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole‐5,5′‐diyl}] ( PocCDT‐TZ ), for use in photovoltaic applications. The intramolecular charge‐transfer interaction between the electron‐sufficient CDT unit and electron‐deficient bithiazole (BT) or thiazolothiazole (TZ) units in the polymeric backbone induced a low bandgap and broad absorption that covered 300 nm to 700–800 nm. The optical bandgap was measured to be around 1.9 eV for PehCDT‐BT and PocCDT‐BT , and around 1.8 eV for PehCDT‐TZ and PocCDT‐TZ . Gel permeation chromatography showed that number‐average molecular weights ranged from 8000 to 14 000 g mol^?1. Field‐effect mobility measurements showed hole mobility of 10^?6–10^?4 cm² V^?1 s^?1 for the copolymers. The film morphology of the bulk heterojunction mixtures with [6,6]phenyl‐C₆₁‐butyric acid methyl ester (PCBM) was also examined by atomic force microscopy before and after heat treatment. When the polymers were blended with PCBM, PehCDT‐TZ exhibited the best performance with an open circuit voltage of 0.69 V, short‐circuit current of 7.14 mA cm^?2, and power conversion efficiency of 2.23 % under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW cm^?2).     

Conformations and rotational barriers of 2,2′‐bithiazole and 4,4′‐dimethyl‐2,2′‐bithiazole semiemperical,ab initio,and density functional theory calculations

Conformational properties of 2,2′‐bithiazole and 4,4′‐dimethyl‐2,2′‐ bithiazole have been studied by using AM1 and PM3 semiemperical methods and ab initio HF/6‐311+G* and B3LYP/6‐311+G* calculations. All methods agree that the planar s‐trans conformation is the global minimum and the perpendicular conformation is the transition state. Additional local minima were found using the Hartree–Fock (HF) and B3LYP levels for 2,2′‐bithiazole while for 4,4′‐dimethyl derivative the minima was located only at the MP2//B3LYP level. The barrier heights for rotation are 1.72, 7.69, and 7.88 kcal/mol at the PM3, HF, and B3LYP levels, respectively, and methyl substitution did not affect appreciably this value. Fourier expansion terms and bond orders were used to explain the origins of the rotational barrier in terms of π conjugation, electrostatic interaction, and steric effects, which represent the main factors in the shape of the rotational barrier. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 367–377, 2000     

On the Reaction of Thiazole‐2,4‐diamines with Isothiocyanates – Preparation and Transformation of 2,4‐Diaminothiazole‐5‐carbothioamides

In the reaction of thiazole‐2,4‐diamines 8 with isothiocyanates 1 , 2,4‐diaminothiazole‐5‐carbothioamides 9, 10, 18 , and 19 as well as thiazolo[4,5‐d]pyrimidine‐7(6H)‐thiones 21 were formed. The carbothioamides 9, 10 , and 18 were transformed by reaction with different types of monofunctional and bifunctional electrophiles into hitherto unknown acceptor‐substituted 4,4′‐([2,5′‐bithiazole]‐2′,4′‐diyl)bis[morpholines] 24 and 29 , the 2′,4′‐bis(dialkylamino)[2,5′‐bithiazol]‐4‐(5H)‐ones 30 , and the 4‐substituted 2′,4′‐bis(dialkylamino)‐2,5′‐bithiazoles 31 . From 30 and 31 new 4‐mono‐ or 4,5‐disubstituted 2′,4′‐bis(dialkylamino)‐2,5′‐bithiazoles 34, 35, 38 , and 39 as well as 5‐substituted 2′,4′‐bis(dialkylamino)[2,5′‐bithiazol]‐4(5H)‐ones 33, 36 , and 37 were prepared.     

Synthesis,Characterization, and Biological Evaluation as Antibacterial Agents of Water‐Soluble Calix[4]arenes and Phenol Derivatives Incorporating Carboxylate Groups

As part of specific investigations dedicated to the building of a chemical library of calixarenes with anti‐infective properties, some H₂O‐soluble calix[4]arene derivatives incorporating carboxylate groups at the upper rim and heterocycles at the lower rim have been prepared and characterized as have their constitutive functional monomers. In vitro antibacterial testing against Gram‐positive and Gram‐negative reference strains shows that the derivative with two 5,5′‐dicarboxylated 2,2′‐bithiazole subunits in alternate positions at the lower rim displays an activity at ca. 70 μM (128 μg/ml) on S. aureus ATCC 29213.     

Fluorene‐based alternating polymers containing electron‐withdrawing bithiazole units: Preparation and device applications

We report here the synthesis via Suzuki polymerization of two novel alternating polymers containing 9,9‐dioctylfluorene and electron‐withdrawing 4,4′‐dihexyl‐2,2′‐bithiazole moieties, poly[(4,4′‐dihexyl‐2,2′‐bithiazole‐5,5′‐diyl)‐alt‐(9,9‐dioctylfluorene‐2,7‐diyl)] (PHBTzF) and poly[(5,5′‐bis(2″‐thienyl)‐4,4′‐dihexyl‐2,2′‐bithiazole‐5″,5″‐diyl)‐alt‐(9,9‐dioctylfluorene‐2,7‐diyl)] (PTHBTzTF), and their application to electronic devices. The ultraviolet–visible absorption maxima of films of PHBTzF and PTHBTzTF were 413 and 471 nm, respectively, and the photoluminescence maxima were 513 and 590 nm, respectively. Cyclic voltammetry experiment showed an improvement in the n‐doping stability of the polymers and a reduction of their lowest unoccupied molecular orbital energy levels as a result of bithiazole in the polymers' main chain. The highest occupied molecular orbital energy levels of the polymers were ?5.85 eV for PHBTzF and ?5.53 eV for PTHBTzTF. Conventional polymeric light‐emitting‐diode devices were fabricated in the ITO/PEDOT:PSS/polymer/Ca/Al configuration [where ITO is indium tin oxide and PEDOT:PSS is poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonic acid)] with the two polymers as emitting layers. The PHBTzF device exhibited a maximum luminance of 210 cd/m² and a turn‐on voltage of 9.4 V, whereas the PTHBTzTF device exhibited a maximum luminance of 1840 cd/m² and a turn‐on voltage of 5.4 V. In addition, a preliminary organic solar‐cell device with the ITO/PEDOT:PSS/(PTHBTzTF + C₆₀)/Ca/Al configuration (where C₆₀ is fullerene) was also fabricated. Under 100 mW/cm² of air mass 1.5 white‐light illumination, the device produced an open‐circuit voltage of 0.76 V and a short‐circuit current of 1.70 mA/cm². The fill factor of the device was 0.40, and the power conversion efficiency was 0.52%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1845–1857, 2005     

An Efficient Synthesis of Spiro‐oxindole Derivatives by Three‐Component Reactions in Water

An efficient synthesis of (3S)‐1,1′,2,2′,3′,4′,6′,7′‐octahydro‐9′‐nitro‐2,6′‐dioxospiro[3H‐indole‐3,8′‐[8H]pyrido[1,2‐a]pyrimidine]‐7′‐carbonitrile is achieved via a three‐component reaction of isatin, ethyl cyanoacetate, and 1,2,3,4,5,6‐hexahydro‐2‐(nitromethylidene)pyrimidine. The present method does not involve any hazardous organic solvents or catalysts. Also the synthesis of ethyl 6′‐amino‐1,1′,2,2′,3′,4′‐hexahydro‐9′‐nitro‐2‐oxospiro[3H‐indole‐3,8′‐[8H]pyrido[1,2‐a]pyrimidine]‐7′‐carboxylates in high yields, at reflux, using a catalytic amount of piperidine, is described. The structures were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS data) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).     

Synthesis,Modification, and Anticonvulsant Activity of 3′‐R1‐Spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′(7′H)‐diones Derivatives

Previously unknown 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazoline]‐2,2′‐(7′H)‐diones and their N‐substituted analogues were obtained via reaction of 6‐R¹‐3‐(2‐aminophenyl)‐1,2,4‐triazin‐5‐ones with isatin and its substituted derivatives. It was shown that alkylation of 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′‐(7′H)‐diones by N‐R³‐chloroacetamides or chloroacetonitrile in the presence of а base proceeds by N‐1 atom of isatin fragment. The spectral properties (¹H and ¹³C NMR spectra) of synthesized compounds were studied, and features of spectral patterns were discussed. The high‐effective anticonvulsant and radical scavenging agents among 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′(7′H)‐diones and their N‐substituted derivatives were detected. It was shown that compounds 2.2 , 2.8 , and 3.1 exceed or compete the activity of the most widely used in modern neurology drug—lamotrigine on the pentylenetetrazole‐induced seizures model. The aforementioned fact may be considered as a reason for further profound study of synthesized compounds using other pathology models.     

Synthesis and Properties of Brominated 6,6'-Dimethyl-[2,2'-bi-1H-indene]-3,3'-diethyl-3,3'-dihydroxy-1,1 '-diones

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 2 ), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 3 ) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 4 ) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 1 ). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4 , molecular arrangement is defective tightness compared with its precursor 1 . Besides, UV‐Vis absorption spectra in CH₂Cl₂ solution, photochromic and photomagnetic properties in solid state of 2 , 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.     

Syntheses of dibenzo[c,e][1,2]diselenin and related novel chalcogenide heterocyclic compounds

Reaction of 2,2′-dilithio-1,1′-binaphthyl with selenium followed by air oxidation gives a mixture of dinaph-thoselenophene and dimer and oligomers of 2,2′-diseleno-1,1′-binaphthyl. 2,2′-Dilithio-1,1′-biphenyl reacts with selenium to afford dibenzo[c,e][1,2]diselenin. Structures of the dimeric 2,2′-diseleno-1,1′-binaphthyl and dibenzo[c,e][1,2]diselenin have been confirmed by X-ray crystallographic analyses. Similar reaction of 2,2′-dilithio-1,1′-binaphthyl with sulfur or tellurium gives a mixture of dinaphthothiophene and dinaphtho[2,1-c:-1′,2′-e][1,2]dithiin or a mixture of dinaphthotellurophene and oligomer of 2,2′-ditelluro-1,1′-binaphthyl, respectively. Dibenzotellurophene and oligomer of 2,2′-ditelluro-1,1′-biphenyl are obtained from reaction of 2,2′-dilithio-1,1′-biphenyl with tellurium.     

An Efficient Synthesis of 3,3′,4,4′‐Tetrahydro‐4,4′‐bibenzo[e][1,3]oxazine‐2,2′‐dione Derivatives with the Aid of Low‐valent Titanium

Synthesis of 3,3′,4,4′‐tetrahydro‐4,4′‐bibenzo[e][1,3]oxazine‐2,2′‐diones via reaction of salicylidendphenylhydrazone and triphosgene with the aid of low‐valent titanium reagent is described. This method has the advantages of accessible starting materials, good yields and short reaction time.     

2,2‐Bis(methoxy‐NNO‐azoxy)ethyl Derivatives of 4,8‐Dihydro‐bis‐furazano[3,4‐b:3′4′‐e]pyrazine: The Synthesis and X‐ray Investigation

The first synthesis of 4,8‐dihydro‐bis‐furazano[3,4‐b:3′4′‐e]pyrazine bearing 2,2‐bis(methoxy‐NNO‐azoxy)ethyl groups has been developed. These compounds are obtained by aza‐Michael reaction of 1,1‐bis(methoxy‐NNO‐azoxy)ethene or its equivalents, such as 2,2‐bis(methoxy‐NNO‐azoxy)ethanol derivatives, with 4,8‐dihydro‐bis‐furazano[3,4‐b:3′4′‐e]pyrazine.     

Synthesis and electroluminescent properties of fluorene‐based copolymers containing electron‐withdrawing thiazole derivatives

We synthesized two fluorene‐based copolymers poly[(2,5‐bis(4‐hexylthiophen‐2‐yl)thiazolo[5,4‐day]thiazole‐5,5′‐diyl)‐alt‐(9,9′‐dioctylfluorene‐2,7‐diyl)] ( PF‐TTZT), and poly[(5,5′‐bis(4‐hexylthiophen‐2‐yl)‐2,2′‐bithiazole‐5,5′‐diyl)‐alt‐(9,9′‐dioctylfluorene‐2,7‐diyl)] (PF‐TBTT), which contain the electron‐withdrawing moieties, thiazolothiazole, and bithiazole, respectively. Through electrochemical studies, we found that these two polymers exhibit stable reversible oxidation and reduction behaviors. Moreover, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of PF‐TBTT are lower than those of PF‐TTZT, and the bandgap of PF‐TBTT is smaller than that of PF‐TTZT. Thus the bithiazole moiety in PF‐TBTT is more electron‐withdrawing than the thiazolothiazole moiety in PF‐TTZT. Light‐emitting devices with indium tin oxide (ITO)/poly(3,4‐ethylene dioxythiophene):poly(styrenesulfonate)(PEDOT)/polymer/bis(2‐methyl‐8‐quinolinato)‐4‐phenylphenolate aluminum (BAlq)/LiF/Al configurations were fabricated. The performance of the PF‐TBTT device was found to be almost three times better than that of the PF‐TTZT device, which is because electron injection from the cathode to PF‐TBTT is much easier than for PF‐TTZT. We also investigated the planarity and frontier orbitals of the electron donor‐acceptor (D‐A) moieties with computational calculations using ab initio Hartree–Fock with the split‐valence 6‐31G* basis set. These calculations show that TBTT has a more nonplanar structure than TTZT and that the bithiazole moiety is more electron‐withdrawing than thiazolothiazole. These calculations are in good agreement with the experimental results. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7148–7161, 2008     

Ring transformations of heterocyclic compounds. XXIII. The UV irradiation product of photochromic 2,4,6‐triaryl‐1‐(spiro[2H‐l‐benzopyran‐2,2′‐indoline]‐6‐yl)pyridinium salts ‐ A phenolate betaine or a pyridinium substituted merocyanine dye?

The synthesis of the novel 2,4,6‐triaryl‐1‐(spiro[2H‐1‐benzopyran‐2,2′‐indoline]‐6‐yl)pyridiniumper‐chlorates 4 by reaction of 5 ‐nitrosalicylaldehydes 6 with 1,3,3‐trimethyl‐2‐methyleneindoline ( 7 ) to 6‐nitro‐spiro[2H‐1‐benzopyran‐2,2′‐indolines] 1 , their stannous chloride reduction to the 6‐amino derivatives 8 , followed by a 2,6‐[C₅+N] ring transformation with 2,4,6‐triarylpyrylium perchlorates 9 , is reported. UV irradiation experiments in twenty solvents of different polarity prove their photochromic properties and show that the photochemically generated negative solvatochromic dyes 5 , formed by ring opening of the benzopyran moiety of 4 , are rather merocyanine than pyridinium phenolate betaine dyes.     

Synthesis of N,N,N-4,4＂-Di-（4-methylphenyl）-2,2＇：6＇,2＂- terpyridine-N,N,N-tris（isothiocyanato） Ruthenium（Ⅱ） and Application to Colorimetric Hg^2＋ Sensor

A terpyridine derivative DPTP [di-（4-methylphenyl）-2,2＇：6＇,2＂-terpyridine] was conveniently synthesized from 2-bromopyridine via halogen-dance reaction, Kharash coupling and Stille coupling reaction. Then its corresponding ruthenium complex Ru-DPTP [N,N,N-4,4＇＇-di-（4-methy,phenyl）-2,2＇：6＇,2＂-terpyridine-N,N,N-tris（is,-thi,cyanat,）- ruthenium（H） ammonium] was obtained and fully characterized by IR, UV-Vis, ESI MS and elemental analysis. The MLCT absorption band of Ru-DPTP was blue-shifted from 570 to 500 nm upon addition of Hg^2＋. Among a series of surveyed metal ions, the complex showed a unique recognition to Hg^2＋, indicating that it can be used as a selective colorimetric sensor for Hg^2＋.     

Methylene‐Bridged Metallocenes with 2,2′‐Methylenebis[1H‐inden‐1‐yl] Ligands: Synthesis,Characterization, and Polymerization Catalysis of a Synthetically Simple Class of C2‐ and C2v‐Symmetric ansa‐Metallocenes

The acid‐catalyzed reaction between formaldehyde and 1H‐indene, 3‐alkyl‐ and 3‐aryl‐1H‐indenes, and six‐membered‐ring substituted 1H‐indenes, with the 1H‐indene/CH₂O ratio of 2 : 1, at temperatures above 60° in hydrocarbon solvents, yields 2,2′‐methylenebis[1H‐indenes] 1 – 8 in 50–100% yield. These 2,2′‐methylenebis[1H‐indenes] are easily deprotonated by 2 equiv. of BuLi or MeLi to yield the corresponding dilithium salts, which are efficiently converted into ansa‐metallocenes of Zr and Hf. The unsubstituted dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1H‐inden‐1‐yl]}zirconium ([ZrCl₂( 1′ )]) is the least soluble in organic solvents. Substitution of the 1H‐indenyl moieties by hydrocarbyl substituents increases the hydrocarbon solubility of the complexes, and the presence of a substituent larger than a Me group at the 1,1′ positions of the ligand imparts a high diastereoselectivity to the metallation step, since only the racemic isomers are obtained. Methylene‐bridged ‘ansa‐zirconocenes’ show a noticeable open arrangement of the bis[1H‐inden‐1‐yl] moiety, as measured by the angle between the planes defined by the two π‐ligands (the ‘bite angle’). In particular, of the ‘zirconocenes’ structurally characterized so far, the dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[4,7‐dimethyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl₂( 5′ )] is the most open. The mixture [ZrCl₂( 1′ )]/methylalumoxane (MAO) is inactive in the polymerization of both ethylene and propylene, while the metallocenes with substituted indenyl ligands polymerize propylene to atactic polypropylene of a molecular mass that depends on the size of the alkyl or aryl groups at the 1,1′ positions of the ligand. Ethene is polymerized by rac‐dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1‐methyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl₂( 2′ )])/MAO to polyethylene waxes (average degree of polymerization ca. 100), which are terminated almost exclusively by ethenyl end groups. Polyethylene with a high molecular mass could be obtained by increasing the size of the 1‐alkyl substituent.     

A novel bithiazole‐containing polymeric complex with soft ferromagnetism

A novel polymer resulting from the polycondensation of 2,2′‐diamino‐4,4′‐bithiazole (DABT) with 5,5′‐methylene‐bis‐salicylaldehyde (MBSA) and its ferric complex are described. Analyses of Fourier transform infrared (FT‐IR) and X‐ray photoelectron spectroscopy (XPS) revealed that both bithiazole residue and Schiff‐base moiety acted as coordination sites for Fe³⁺ ions in the polymeric matrix. The magnetic behavior of the complex was studied as a function of magnetic field strength (0–60 kOe) at 25 K and as a function of temperature (5–300 K) at a magnetic field strength of 30 kOe. The hysteretic loop was measured at 5 K for the complex showing coercivity (H_c) of 20 Oe and remnant magnetization (M_r) of 0.002 emu/g, which is much lower than those of bithiazole‐based polymeric complexes previously reported. The results indicated that the present complex is of the typical characteristics of a soft ferromagnet. Copyright © 2005 John Wiley & Sons, Ltd.     

Group 3 Metal Initiators with an [OSSO]‐Type Bis(phenolate) Ligand for the Stereoselective Polymerization of Lactide Monomers

A series of 1,ω‐dithiaalkanediyl‐bridged bis(phenols) of the general type [OSSO]H₂ with variable steric properties and various bridges were prepared. The stoichiometric reaction of the bis(phenols) 1,3‐dithiapropanediyl‐2,2′‐bis(4,6‐di‐tert‐butylphenol), 1,3‐dithiapropanediyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], rac‐2,3‐trans‐propanediyl‐1,4‐dithiabutanediyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], rac‐2,3‐trans‐butanediyl‐1,4‐dithiabutane diyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], rac‐2,3‐trans‐hexanediyl‐1,4‐dithiabutanediyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], 1,3‐dithiapropanediyl‐2,2′‐bis[6‐(1‐methylcyclohexyl)‐4‐methylphenol] (C₁, R=1‐methylcyclohexyl), and 1,4‐dithiabutanediyl‐2,2′‐bis[6‐(1‐methylcyclohexyl)‐4‐methylphenol] with rare‐earth metal silylamido precursors [Ln{N(SiHMe₂)₂}₃(thf)_x] (Ln=Sc, x=1 or Ln=Y, x=2; thf=tetrahydrofuran) afforded the corresponding scandium and yttrium bis(phenolate) silylamido complexes [Ln(OSSO){N(SiHMe₂)₂}(thf)] in moderate to good yields. The monomeric nature of these complexes was shown by an X‐ray diffraction study of one of the yttrium complexes. The complexes efficiently initiated the ring‐opening polymerization of rac‐ and meso‐lactide to give heterotactic‐biased poly(rac‐lactides) and highly syndiotactic poly(meso‐lactides). Variation of the ligand backbone and the steric properties of the ortho substituents affected the level of tacticity in the polylactides.     

Labelling of Carbaboranyl Compounds with a Selenium Atom with a View to Applications in Boron‐Neutron‐Capture Therapy (BNCT) and Positron‐Emission Tomography (PET)

We synthesized 2′‐carbaboranyl‐2,5′‐bi‐1H‐benzimidazoles containing 10 B‐atoms and labeled with Se or the positron‐emitting radionuclide ⁷³Se (t_1/2=7.1 h), with a view to their application to cancer treatment by boron‐neutron‐capture therapy (BNCT) and to compound‐distribution measurements in vivo by positron‐emission tomography (PET). Thus, 2,2′‐{{2′‐{4‐[1,2‐dicarba‐closo‐dodecaboran(12)‐2‐ylmethoxy]phenyl}‐[2,5′‐bi‐1H‐benzimidazol]‐5‐yl}imino}bis[ethanol] ( 26c ) was obtained by the reaction of 2,2′‐[(3,4‐diaminophenyl)imino]bis[ethanol] ( 19 ) with ethyl 2‐{4‐[1,2‐dicarba‐closo‐dodecaboran(12)‐2‐ylmethoxy]phenyl}‐1H‐benzimidazole‐5‐carboximidate hydrochloride ( 25 ), as well as the analogues 26a and 26b (Scheme 6). Tosylation of compound 26c gave 4 regioisomers 27a – d , which, after selenation, produced 2′‐{4‐[1,2‐dicarba‐closo‐dodecaboran(12)‐2‐ylmethoxy]phenyl}‐5‐(tetrahydro‐2H‐1,4‐selenazin‐4‐yl)‐2,5′‐bi‐1H‐benzimidazole ( 29 ) in 42% yield (Scheme 7).