Synthesis and Characterization of m‐Terphenyl (1,3‐Diphenylbenzene) Compounds Containing Trifluoromethyl Groups

The bis(silyl)triazene compound 2,6‐(Me₃Si)₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 4 ) was synthesized by double lithiation/silylation of 2,6‐Br₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 1 ). Furthermore, 2,6‐bis[3,5‐(CF₃)₂‐C₆H₃]‐4‐Me‐C₆H₂‐1‐(N?N? NC₄H₈)C₆H₂ derivative 6 can be easily synthesized by a C,C‐bond formation reaction of 1 with the corresponding aryl‐Grignard reagent, i.e., 3,5‐bis[(trifluoromethyl)phenyl]magnesium bromide. Reactions of compound 4 with KI and 6 with I₂ afforded in good yields novel phenyl derivatives, 2,6‐(Me₃Si)₂‐4‐MeC₆H₂? I and 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]‐4‐MeC₆H₂? I ( 5 and 7 , resp.). On the other hand, the analogous m‐terphenyl 1,3‐diphenylbenzene compound 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]C₆H₃? I ( 8 ) could be obtained in moderate yield from the reaction of (2,6‐dichlorophenyl)lithium and 2 equiv. of aryl‐Grignard reagent, followed by the reaction with I₂. Different attempts to introduce the ^tBu (Me₃C) or neophyl (PhC(Me)₂CH₂) substituents in the central ring were unsuccessful. All the compounds were fully characterized by elemental analysis, melting point, IR and NMR spectroscopy. The structure of compound 6 was corroborated by single‐crystal X‐ray diffraction measurements.     

Organometallic Diaza‐dimetalla‐Norbornanes and ‐Cyclohexanes of Aluminium,Gallium and Indium

Selective formation of 1,3,3,4,6,6‐hexamethyl‐1,4‐diaza‐3,6‐diinda‐norborane was achieved by the reaction of bis(lithiomethyl‐methylamino)methane with dimethylindium chloride by simultaneous formation of two dative metal‐carbon and two metal‐nitrogen bonds accompanied by two ring closures. The synthesis of heterometallic compounds of this type, namely 1,3,3,4,6,6‐hexamethyl‐3‐alumina‐1,4‐diaza‐6‐galla‐norborane [Me₂AlCH₂N(Me)]CH₂[N(Me)CH₂GaMe₂], was also attempted by the reaction of bis(lithiomethyl‐methylamino)methane with dimethylaluminium and ‐gallium chloride. This compound is formed, but cannot be separated from the simultaneously formed homometallic compounds [Me₂MCH₂N(Me)]₂CH₂(M = Al, Ga). The compounds were identified by elemental analyses, mass spectra, NMR spectroscopy (¹H, ¹³C), and by determination of their crystal structures in which they are present as monomers. The norbornane‐like structure is favoured over potential isomers containing three‐membered rings and over polymeric aggregation in both compounds. In addition, the crystal structure of dimethyl(dimethylaminomethyl)indium was determined by single crystal X‐ray diffraction, which shows an intermolecular aggregation into a six‐membered ring dimer.     

Silicon‐ and Tin‐Containing Open‐Chain and Eight‐Membered‐Ring Compounds as Bicentric Lewis Acids toward Anions

Herein, we report the syntheses of silicon‐ and tin‐containing open‐chain and eight‐membered‐ring compounds Me₂Si(CH₂SnMe₂X)₂ ( 2 , X=Me; 3 , X=Cl; 4 , X=F), CH₂(SnMe₂CH₂I)₂ ( 7 ), CH₂(SnMe₂CH₂Cl)₂ ( 8 ), cyclo‐Me₂Sn(CH₂SnMe₂CH₂)₂SiMe₂ ( 6 ), cyclo‐(Me₂SnCH₂)₄ ( 9 ), cyclo‐Me_(2?n)X_nSn(CH₂SiMe₂CH₂)₂SnX_nMe_(2?n) ( 5 , n=0; 10 , n = 1, X= Cl; 11 , n=1, X= F; 12 , n=2, X= Cl), and the chloride and fluoride complexes NEt₄[cyclo‐ Me(Cl)Sn(CH₂SiMe₂CH₂)₂Sn(Cl)Me?F] ( 13 ), PPh₄[cyclo‐Me(Cl)Sn(CH₂SiMe₂CH₂)₂Sn(Cl)Me?Cl] ( 14 ), NEt₄[cyclo‐Me(F)Sn(CH₂SiMe₂CH₂)₂Sn(F)Me?F] ( 15 ), [NEt₄]₂[cyclo‐Cl₂Sn(CH₂SiMe₂CH₂)₂SnCl₂?2 Cl] ( 16 ), M[Me₂Si(CH₂Sn(Cl)Me₂)₂?Cl] ( 17 a , M=PPh₄; 17 b , M=NEt₄), NEt₄[Me₂Si(CH₂Sn(Cl)Me₂)₂?F] ( 18 ), NEt₄[Me₂Si(CH₂Sn(F)Me₂)₂?F] ( 19 ), and PPh₄[Me₂Si(CH₂Sn(Cl)Me₂)₂?Br] ( 20 ). The compounds were characterised by electrospray mass‐spectrometric, IR and ¹H, ¹³C, ¹⁹F, ²⁹Si, and ¹¹⁹Sn NMR spectroscopic analysis, and, except for 15 and 18 , single‐crystal X‐ray diffraction studies.     

Versatile Conversion of N‐Heterocyclic Silylene to Silyl Metal Compounds by Insertion of Divalent Silicon into Metal–Carbon and Metal–Hydrogen Bonds

The facile one‐pot reaction of the stable N‐heterocyclic silylene LSi: 1 (L?(ArN)C(?CH₂) CH?C(Me)(NAr), Ar=2,6‐iPr₂C₆H₃) with Me₂Zn, Me₃Al, H₃Al‐NMe₃, and MeLi has been investigated. The silicon(II) atom in 1 is capable of insertion into the corresponding M? C and Al? H bonds under very mild reaction conditions. Thus, Me₂Zn furnishes the bis(silyl) zinc complex LSi(Me)ZnSi(Me)L 2 as the sole product, irrespective of the molar ratio of the starting materials applied. Moreover, the reactions of 1 with Me₃Al, H₃Al‐NMe₃, and MeLi lead directly to the 1,1‐addition products LSi(Me)(Al(thf)Me₂) 3 , LSi(H)(AlH₂(NMe₃)) 4 , and LSi(Me)Li(thf)₃ 5 , respectively. All new compounds 2 – 5 were fully characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses, and single‐crystal X‐ray diffraction analyses.     

Synthesis and Reactivity of Low‐Valent Group 14 Element Compounds

The tetravalent germanium and tin compounds of the general formulae Ph*EX₃ (Ph* = C₆H₃Trip‐2,6, Trip = C₆H₂iPr₃‐2,4,6; E = Sn, X = Cl ( 1a ), Br ( 1b ); E = Ge, X = Cl ( 2 )) are synthesized by reaction of Ph*Li·OEt₂ with EX₄. The subsequent reaction of 1a , b with LiP(SiMe₃)₂ leads to Ph*EP(SiMe₃)₂ (E = Sn ( 3 ), Ge ( 4 )) and the diphosphane (Me₃Si)₂PP(SiMe₃)₂ by a redox reaction. In an alternative approach 3 and 4 are synthesized by using the corresponding divalent compounds Ph*ECl (E = Ge, Sn) in the reaction with LiP(SiMe₃)₂. The reactivity of Ph*SnCl is extensively investigated to give with LiP(H)Trip a tin(II)‐phosphane derivative Ph*SnP(H)Trip ( 6 ) and with Li₂PTrip a proposed product [Ph*SnPTrip]^– ( 7 ) with multiple bonding between tin and phosphorus. The latter feature is confirmed by DFT calculations on a model compound [PhSnPPh]^–. The reaction with Li[H₂PW(CO)₅] gives the oxo‐bridged tin compound [Ph*Sn{W(CO)₅}(μ‐O)₂SnPh*] ( 8 ) as the only isolable product. However, the existence of 8 as the bis‐hydroxo derivative [Ph*Sn{W(CO)₅}(μ‐OH)₂SnPh*] ( 8a ) is also possible. The Sn^IV derivatives Ph*Sn(OSiMe₃)₂Cl ( 9 ) and [Ph*Sn(μ‐O)Cl]₂ ( 10 ) are obtained by the oxidation of Ph*SnCl with bis(trimethylsilyl)peroxide and with Me₃NO, respectively. Besides the spectroscopic characterization of the isolated products compounds 1a , 2 , 3 , 4 , 8 , and 10 are additionally characterized by X‐ray diffraction analysis.     

Dichloro[1,1′‐(5,9‐dithia‐2,12‐diazoniatrideca‐1,12‐diene‐1,13‐diyl)dinaphthalen‐2‐olato‐κ2O,O′]dimethyltin(IV) acetonitrile solvate

Reaction of the potentially hexadentate ligand 1,9‐bis(2‐hydroxy‐1‐naphthalene­methyl­imino)‐3,7‐di­thia­nonane with di­methyl­tin chloride gave the title 1:1 adduct, in which the long ligand wraps around the SnCl₂Me₂ unit and in which the stereochemistry is fully trans. This compound crystallizes from aceto­nitrile as the 1:1 solvate [Sn(CH₃)₂(C₂₉H₃₀N₂­O₂S₂)Cl₂]·­C₂H₃N. During the reaction, the hydroxyl protons move to the N atoms. Most of the chemically equivalent bond lengths agree to within experimental uncertainty, but the Sn—Cl bond that is inside the ligand pocket is substantially longer than the Sn—Cl bond that points away from the long ligand [2.668 (1) versus 2.528 (1) Å]. The O—Sn—O angle is 166.0 (1)°. Comparison of the Sn—O, C—O and aryl C—C bond lengths with those of related compounds shows that the most important resonance forms for the Schiff base aryl­oxide ligand are double zwitterions, but that the uncharged resonance forms having carbonyl groups also contribute significantly.     

Synthese und Struktur C,N‐difunktionalisierter Sulfinimidamide

Synthesis and Structure of C,N‐difunctionalized Sulfinimideamides Sulfurdiimides RN=S=NR ( 1 a , b ) react in diethyl ether with two equivalents of lithiummethyl to give dimeric C,N‐dilithiummethylenesulfinimideamide ether adducts {Li₂[H₂C–S(NR)₂ · Et₂O]}₂ ( 2 a , b ) ( a : R = ^tBu, b : R = SiMe₃). Metathesis of 2 b with four equivalents of Me₃SiCl, Me₃SnCl or Ph₃SnCl yields the corresponding C,N‐bis‐substituted sulfinimideamides R₃EH₂C–S[N(SiMe₃)₂]NER₃ ( 3 – 5 ) ( 3 : R = Me, E = Sn; 4 : R = Ph, E = Sn; 5 : R = Me, E = Si). The crystal structures of 2 a and 2 b were determined by X‐ray structure analysis. Both compounds form centrosymmetric cage structures consisting of two distorted face sharing cubes ( 2 a : space group P1 (No. 2); Z = 2 (4 · 0,5); 2 b : space group C2/c (No. 15), Z = 4).     

tert‐Butyldiphenylsilylhydrazin – ein Baustein für Tetrakis‐silylhydrazine,Silylhydrazone und O‐Silylpyrazolone

tert ‐Butyldiphenylsilylhydrazine – Precursors for Tetra(silyl)hydrazines, Silylhydrazones, and O‐Silylpyrazolones tert‐Butylchlorodiphenylsilane reacts with hydrazine in presence of triethylamine to give the mono(silyl)hydrazine Me₃CSiPh₂NHNH₂ ( 1 ). The lithium derivative of 1 ( 1 a ) forms the N,N′‐bis(silyl)hydrazines 2 and 3 in the reaction with chlorosilanes. ( 2 : Me₃CSiPh₂NHNHSiPh₂CMe₃; 3 : Me₃CSiPh₂NHNHSiMe₂CMe₃). The monomeric dilithiumhydrazide 4 , (Me₃CSiPh₂)₂N₂Li₂(THF)₃, is obtained from 2 and the bimolar amount of C₄H₉Li in THF. 4 reacts with an excess of SiF₄ to give the tetra(silyl)hydrazine 5 , Me₃CSiPh₂(SiF₃)N–N(SiF₃)SiPh₂CMe₃. 1 and ketones undergo condensation to silylhydrazones, Me₃CSiPh₂NHN=C(Me)R ( 6 : R = Me; 7 : R = CMe₃), with elimination of H₂O. Only one of the two possible isomers of 7 is formed. Cis/trans isomers ( 8 a , b ) are obtained in the analogous reaction of 1 and ethyl acetoacetate, Me₃CSiPh₂NH–N=CMe–CH₂–COOEt ( 8 a , b ). 8 condenses thermally with elimination of EtOH and formation of the O‐silylpyrazolone 9 , Me₃CSiPh₂O–(C=N–NH–CMe=CH–). The results of the crystal structure analysis of the compounds 2 , 4 , and 7 are reported.     

Formation of an Imino‐Stabilized Cyclic Tin(II) Cation from an Amino(imino)stannylene

The novel amino(imino)stannylene 1 was prepared by conversion of HNIPr (NIPr=bis(2,6‐diisopropylphenyl)imidazolin‐2‐imino) with one equivalent of Lappert’s tin reagent (Sn[N(SiMe₃)₂]₂). Treatment of 1 with DMAP (4‐dimethylaminopyridine) yields its Lewis acid–base adduct 2 . The reaction of 1 with one equivalent of trimethylsilyl azide results in replacement of the amino group at the tin center by an N₃ substituent with concomitant elimination of N(SiMe₃)₃ to afford dimeric [N₃SnNIPr]₂ ( 3 ). Remarkably, the reaction of 1 with B(C₆F₅)₃ produces the novel tin(II) monocation 4 ⁺[MeB(C₆F₅)₃]^? comprising a four‐membered stannacycle through methyl‐abstraction from the trimethylsilyl group.     

Transient Silenes as Versatile Synthons – The Reaction of Dichloromethyl‐tris(trimethylsilyl)silane with Organolithium Reagents

Treatment of dichloromethyl‐tris(trimethylsilyl)silane (Me₃Si)₃Si–CHCl₂ ( 1 ), prepared by the reaction of tris(trimethylsilyl)silane with chloroform in presence of potassium tertbutoxide, with organolithium reagents (molar ratio 1 : 3) affords the bis(trimethylsilyl)methyl‐disilanes Me₃SiSiR₂–CH(SiMe₃)₂ ( 12 a–d ) ( a : R = Me, b : R = n‐Bu, c : R = Ph, d : R = Mes). The formation of 12 a–d is discussed as proceeding through an exceptional series of isomerization and addition reactions involving intermediate silyl substituted carbenoids and transient silenes. The carbenoid (Me₃Si)₂PhSi–C(SiMe₃)LiCl ( 8 c ) is moderately stable at low temperature and was trapped with water to give (Me₃Si)₂PhSi–CH(SiMe₃)Cl ( 9 c ) and with chlorotrimethylsilane affording (Me₃Si)₂PhSi–CCl(SiMe₃)₂ ( 7 c ). For 12 d an X‐ray crystal structure analysis was performed, which characterizes the compound as a highly congested silane with bond parameters significantly deviating from standard values.     

Synthese und Struktur hochfunktionalisierter 2, 3‐Dihydro‐1H‐1, 3, 2‐diazaborole

Synthesis and Structure of Highly Functionalized 2, 3‐Dihydro‐1H‐1, 3, 2‐diazaboroles A series of differently substituted 2, 3‐dihydro‐1H‐1, 3, 2‐diazaboroles has been prepared by various methods. 1, 3‐Di‐tert‐butyl‐2‐trimethylsilylmethyl‐1H‐1, 3, 2‐diazaborole ( 7 ), 2‐isobutyl‐1, 3‐bis(1‐cyclohexylethyl)‐1H‐1, 3, 2‐diazaborole ( 8 ), 1, 3‐bis‐(1‐cyclohexylethyl)‐2‐trimethylsilylmethyl‐1H‐1, 3, 2‐diazaborole ( 9 ) 1, 3‐bis(1‐methyl‐1‐phenyl‐propyl)‐2‐trimethylsilylmethyl‐1H‐1, 3, 2diazaborole ( 10 ) and 2‐bromo‐1, 3‐bis(1‐methyl‐1‐phenyl‐propyl)‐1H‐1, 3, 2‐diazaborole ( 11 ) were formed by reaction of the corresponding 1, 4‐diazabutadienes with the boranes Me₃SiCH₂BBr₂, iBuBBr₂ and BBr₃ followed by reduction of the resulting borolium salts [R¹ = tBu, Me(cHex)CH, [Me(Et)Ph]C; R² = Me₃SiCH₂, iBu, Br] with sodium amalgam. Treatment of 11 and 12 with silver cyanide afforded the 2‐cyano‐1, 3, 2‐diazaboroles 13 and 14 . An alternative route to compound 8 is based on the alkylation of 2‐bromo‐1, 3, 2‐diazaborole 12 with isobutyllithium. Equimolar amounts of 13 and isobutyllithium give rise to the formation of 15 . The new compounds were characterized by ¹H‐, ¹³C‐, ¹¹B‐NMR, IR and mass spectra. The molecular structures of 7 and meso ‐10 were confirmed by x‐ray structural analysis.     

2,2‐Difluor‐1,3‐diaza‐2‐sila‐cyclopenten – Synthese und Reaktionen

2,2‐Difluor‐1,3‐diaza‐2‐sila‐cyclopentene – Synthesis and Reactions N,N′‐Di‐tert‐butyl‐1,4‐diaza‐1,3‐butadiene reacts with elemental lithium under reduction to give a dilithium salt, which forms with fluorosilanes the diazasilacyclopentenes 1 – 4 ; (HCNCMe₃)₂SiFR, R = F ( 1 ), Me ( 2 ), Me₃C ( 3 ), N(CMe₃)SiMe₃ ( 4 ). As by‐product in the synthesis of 1 , the tert‐butyl‐amino‐methylene‐tert‐butyliminomethine substituted compound 5 was isolated, R = N(CMe₃)‐CH₂‐CH = NCMe₃. 5 is formed in the reaction of 1 with the monolithium salt of the 1,4‐diaza‐1,3‐butadiene in an enamine‐imine‐tautomerism. 1 reacts with lithium amides to give (HCNCMe₃)₂SiFNHR, 6 – 12 , R = H ( 6 ), Me ( 7 ), Me₂CH ( 8 ), Me₃C ( 9 ), H₅C₆ ( 10 ), 2,6‐Me₂C₆H₃ ( 11 ), 2,6‐(Me₂CH)₂C₆H₃ ( 12 ). The reaction of 12 with LiNH‐2.6‐(Me₂CH)₂C₆H₃ leads to the formation of (HCNCMe₃)₂Si(NHR)₂, ( 13 ). In the presence of n‐BuLi, 12 forms a lithium salt which looses LiF in boiling toluene. Lithiated 12 adds this LiF and generates a spirocyclic tetramer with a central eight‐membered LiF‐ring ( 14 ), [(HCNCMe₃)₂Si(FLiFLiNR)]₄, R = 2,6‐(Me₂CH)₂C₆H₃. ClSiMe₃ reacts with lithiated 12 to yield the substitution product (HCNCMe₃)₂SiFN(SiMe₃) R, ( 15 ). The crystal structures of 1 , 5 , 6 , 9 , 11 , 13 , 14 are reported.     

Ein ungewöhnlicher ambivalenter Zinn(II)‐oxo‐Cluster

An Unusual Ambivalent Tin(II)‐oxo Cluster The reaction of the copper aryl CuDmp (Dmp = 2, 6‐Mes₂C₆H₃; Mes = 2, 4, 6‐Me₃C₆H₂) with the stannanediyl Sn{1, 2‐(tBuCH₂N)₂C₆H₄} followed by hydrolysis affords in the presence of lithium‐tert‐butoxide the tin(II)‐oxo cluster {(Et₂O)(LiOtBu)(SnO)(CuDmp)}₂ ( 5 ) in small yield. The solid state structure of the colorless compound shows a central Li₂Sn₂O₂(OtBu)₂ fragment with heterocubane structure. In addition, the Li‐acceptor and O(Sn)‐donor atoms are used for the coordination of one molecule diethylether and copper aryl CuDmp, respectively.     

Lithium Cyanide Supported by O‐ and N‐Donors

A series of adducts of LiCN, namely [Li(Me₂CO₃)CN], [Li(Et₂CO₃)CN], and [Li(NMP)CN] (NMP = N‐methyl‐2‐pyrrolidone) were prepared by treatment of solvent‐free LiCN with the appropriate donor. The starting material for these approaches, donor‐free LiCN, was quantitatively prepared from Me₃SiCN and Li[Me] in diethyl ether at 0 °C. Alternatively, [Li(NMP)CN] was synthesized by metathesis reaction of LiCl with NaCN in the presence of stoichiometric amounts of NMP. Although [Li(Me₂CO₃)CN] and [Li(Et₂CO₃)CN] are water‐sensitive compounds and decompose at the exposure to air, [Li(NMP)CN] is stable in air, even at elevated temperatures. The thermal stability of [Li(NMP)CN] was proven by differential thermal analysis (DTA). [Li(NMP)CN] shows thermal stability up to temperatures of about 132 °C. To evaluate the cyanation ability the reactions of 1‐bromooctane and 3‐bromocyclohexene with unsupported LiCN, [Li(NMP)CN], and a mixture of NaCN/LiCl/NMP were investigated. We found that [Li(NMP)CN] as well as LiCl/NaCN/NMP are efficient cyanation reagents comparable to the expensive and air‐sensitive, donor‐free LiCN. A product of the chloride‐cyanide‐bromide exchange could be isolated and structurally characterized by X‐ray diffraction.     

1,4‐Diiodobenzene with –COO–TEMPO (TEMPO = 2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐4‐yl) substituents at 2,5‐positions: synthesis and use as a monomer for new π‐conjugated polymers having nitroxyl radicals in side chains

The reaction of 2,5‐diiodo‐1,4‐benzenedicarbonyl chloride, C₆H₂I₂(COCl)₂‐p, with 4‐hydroxy‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO‐ol) gave I–Ph(COO–TEMPO)₂–I, Monomer‐1. Pd‐catalyzed polycondensation of Monomer‐1 with Me₃Sn‐Th‐SnMe₃ (2,5‐bis(trimethylstannyl)thiophene) and Bu₃Sn–CH = CH–SnBu₃ (1,2‐bis‐(tributylstannyl)ethylene) gave the corresponding π‐conjugated polymers, Polymer‐1 and Polymer‐2, respectively. Monomer‐1 was converted to a diethynyl compound, H–C ≡ C–Ph(COO–TEMPO)₂–C ≡ C–H (Monomer‐1'), and Pd‐catalyzed polycondensation between Monomer‐1 and Monomer‐1' gave a π‐conjugated poly(arylene ethynylene) type polymer, Polymer‐3. According to the expansion of the π‐conjugation system by the polymerization, the UV–vis peaks of Monomer‐1 (λ_max = 323 nm) and Monomer‐1' (327 nm) are shifted to longer wavelengths (λ_max = 365 nm, 385 nm, and 396 nm for Polymer‐1, Polymer‐2, and Polymer‐3, respectively). Polymer‐1–Polymer‐3 showed ESR signals at about g = 2.01 with reasonable intensities. They are electrochemically active and showed a peak current anodic (oxidation) peak at about 0.9 V versus Ag/AgCl, which is reasonable for TEMPO polymers. Copyright © 2013 John Wiley & Sons, Ltd.     

Zum Reaktionsverhalten lithiierter Aminosilane RR′ Si(H)N(Li)SiMe3

The Reaction Behaviour of Lithiated Aminosilanes RR′Si(H)N(Li)SiMe₃ The bis(trimethylsilyl)aminosubstituted silances RR′Si(H)N(SiMe₃)₂ 11 – 16 (R,R′ = Me, Me₃SiNH, (Me₃Si)₂N) are obtained by the reaction of the lithium silylamides RR′Si(H)N(Li)SiMe₃ 1 – 10 (R,R′ = Me₃SiNLi, Me, Me₃SiNH, (M₃Si)₂N) with chlorotrimethylsilane in the polar solvent tetrahydrofurane (THF). In the reaction of the lithium silylamides [(Me₃Si)₂N]₂(Me₃SiNLi)SiH 10 with chlorotrimethylsilane in THF the rearranged product 1,1,3-tris[bis(trimethylsilyl)amino]-3-methyl-1,3-disila-butane [(Me₃Si)₂N]₂Si(H)CH₂SiMe₂N(SiMe₃)₂ 17 is formed. The reaction of the lithium silyamides RR′ Si(H)N(Li)SiMe₃ 1 – 3 (1: R = R′ = Me; 2: R = Me, R′ = Me₃SiNH; 3: R = Me, R′ = Me₃SiNLi) with chlorotrimethylsilane in the nonpolar solvent n-hexane gives the cyclodisilazanes [RR′ Si? NSiMe₃]₂ 18 – 22 (R = Me, Me₃SiNH, (Me₃Si)₂N; R′ = Me, Me₃SiNH, (Me₃Si)₂N, N(SiMe₃)Si · Me(NHSiMe₃)₂) and trimethylsilane. The lithium silylamides 4 , 5 , 6 , 9 , 10 (4: R = R′ = Me₃SiNH; 5: R = Me₃SiNH, R′ = Me₃SiNLi; 6: R = R′ = Me₃SiNLi; 9: R = (Me₃Si)₂N, R ′ = Me₃SiNLi; 10: R = R′ = (Me₃Si)₂N) shows with chlorotrimethylsilane in n-hexane no reaction. The crystal structure of 17 and 21 are reported.     

Mono‐ and Binuclear Dimethylthallium(III) Complexes with o‐Benzoquinone‐TTF‐o‐Benzoquinone Ligand; Synthesis,Spectroscopy and X‐ray Study

The new mono‐ and binuclear semiquinonato dimethylthallium complexes (Q‐TTF‐SQ)TlMe₂ ( 1 ) and Me₂Tl(SQ‐TTF‐SQ)TlMe₂ ( 2 ) based on di‐o‐quinone with tetrathiafulvalene (TTF) bridge, 4,4′,7,7′‐tetra‐tert‐butyl‐2,2′‐bis‐1,3‐benzodithiol‐5,5′,6,6′‐tetraone Q‐TTF‐Q, were synthesized by the reaction between corresponding mono‐ and di‐sodium semiquinonates (Q‐TTF‐SQ)Na and Na(SQ‐TTF‐SQ)Na and one or two equivalents of Me₂TlCl, respectively. The same products could be obtained by the interaction of Q‐TTF‐Q with one or two equivalents of Me₃Tl. Complexes 1 and 2 were characterized by IR and electronic absorption spectroscopy, EPR, and magnetic measurements. The molecular structures of 1 and 2 were determined by single‐crystal X‐ray diffraction. It was found that mono‐semiquinonato derivative 1 partially disproportionates into Q‐TTF‐Q and binuclear complex 2 in THF solution. According to variable temperature magnetic susceptibility measurements and EPR data, compound 1 reveals paramagnetic behavior with an S = 1/2 state in the range 50–300 K, whereas compound 2 has an S = 0 ground state as the consequence of antiferromagnetic coupling between semiquinonato moieties realized through the TTF‐bridge.     

A DFT Quantum‐Chemical Study of the Structure of Precursors and Active Sites of Catalyst Based on 2,6‐Bis(imino)pyridyl Fe(II) Complexes

Summary: A DFT method has been applied for quantum‐chemical calculations of the molecular structure of charge‐neutral complex LFeMe(μMe)₂AlMe₂ which is formed in system LFeMe₂ + AlMe₃ (L = 2,6‐bis(imino)pyridyl). Calculations suggested the formation of highly polarized complex LFeMe(μMe)₂AlMe₂ ( II ) in system LFeMe₂ + AlMe₃, characterized by r(Fe μMe) = 3.70 Å and r(Al μMe) = 2.08 Å and deficient electron density on fragment [LFeMe]^Q (Q = +0.80 e). Polarization of the complex progresses with the bounding of two AlMe₃ molecules (complex LFeMe(μMe)₂AlMe₂ · 2AlMe₃ ( III )) and with replacement of AlMe₃ by MeAlCl₂ (complex LFeMe(μMe)₂AlCl₂ ( IV )). The activation energy of ethylene insertion into the Fe Me bond of these complexes has been calculated. It was found that the heat of π‐complex formation increases with increasing of polarization extent in the order II < III < IV . Activation energy of the insertion of coordinated ethylene into Fe Me bond decreases in the same order: II > III > IV .

Calculated model complex (NH₃)₃FeMe₂; tridentate bis(imino)pyridyl ligand was substituted by three coplanar NH₃ groups.     

Offenkettige und cyclische As‐funktionalisierte Stannylarsine: Darstellung,Reaktionen und Struktur

Open‐Chain and Cyclic As‐functionalized Stannylarsines: Synthesis, Reactions, and Structure ^tBu₃SnAsH₂ ( 1 ) reacts with MeLi to form the lithium compound ^tBu₃SnAsHLi which reacts with ^tBu₂SnCl₂ to give the AsH‐functionalized bis(arsino)stannane ^tBu₂Sn(AsHSn^tBu₃)₂ ( 2 ). Metallation of diarsadistannetane (^tBu₂SnAsH)₂ ( 3 ) with two equivalents of ^tBuLi yields the dilithio compound (^tBu₂SnAsLi)₂ which reacts with Me₃SiCl or Me₃SnCl to give the corresponding As,As′‐bis‐substituted diarsadistannetanes (^tBu₂SnAsSiMe₃)₂ ( 4 ) and (^tBu₂SnAsSnMe₃)₂ ( 5 ), respectively. The novel compounds are characterized by NMR (¹H, ¹¹⁹Sn) and mass spectroscopy, ring compounds 4 and 5 further by X‐ray structure analysis. In the solid state both ring compounds contain molecules with planar tin‐arsenic rings and two trans‐configurated Me₃Si‐ or Me₃Sn‐ring substituents (space group P2₁/n (No. 14), Z = 2).     

Nitro‐substituted iron(II) tridentate bis(imino)pyridine complexes as high‐temperature catalysts for the production of α‐olefins

A new series of nitro‐substituted bis(imino)pyridine ligands {2,6‐bis[1‐(2‐methyl‐4‐nitrophenylimino)ethyl]pyridine, 2,6‐bis[1‐(4‐nitrophenylimino)ethyl]pyridine, (1‐{6‐[1‐(4‐nitro‐phenylimino)‐ethyl]‐pyridin‐2‐yl}‐ethylidene)‐(2,4,6‐trimethyl‐phenyl)‐amine, and 2,6‐bis[1‐(2‐methyl‐3‐nitrophenylimino)ethyl]pyridine} and their corresponding Fe(II) complexes [{p‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐ Me? p‐NO₂}FeCl₂ ( 10 ), L₂FeCl₂ ( 11 ), {m‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? m‐NO₂}FeCl₂ ( 12 ), and {p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Mes}FeCl₂ ( 14 )] were synthesized. According to X‐ray analysis, there were shortenings of the axial Fe? N bond lengths (up to 0.014 Å) in para‐nitro‐substituted complex 10 and (up to 0.015 Å) in meta‐nitro‐substituted complex 12 versus the Fe(II) complex without nitro groups [{o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me}FeCl₂ ( 1 )]. Complexes 10 , 12 , and 14 afforded very active catalysts for the production of α‐olefins and were more temperature‐stable and had longer lifetimes than parent non‐nitro‐substituted Fe(II) complex 1 . The reaction between FeCl₂ and a sterically less hindered ligand [p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Ph? p‐NO₂] resulted in the formation of octahedral complex 11 . A para‐dialkylamino‐substituted bis(imino)pyridine ligand [p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂] and the corresponding Fe(II) complex [{p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂}FeCl₂ ( 16 )] were synthesized to evaluate the effect of enhanced electron donation of the ligand on the catalytic performance. According to X‐ray analysis, there was a shortening (up to 0.043 Å) of the axial Fe? N bond lengths in para‐diethylamino‐substituted complex 16 in comparison with parent Fe(II) complex 1 . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2615–2635, 2006