Organometallic and related imidotitanium compounds containing a pendant arm functionalised benzamidinate ligand

Chloride ligand substitution reactions of tert-butyl- and arylimido-titanium complexes supported by the pendant arm functionalised N-trimethylsilyl benzamidinate ligand Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂ are described. Reaction of previously-described [Ti(N^tBu){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}Cl] (1) with PhLi afforded thermally sensitive [Ti(N^tBu){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}Ph] (2). The corresponding reaction of 1 with MeLi afforded [Ti(N^tBu){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}Me] (3) detected by ¹H-NMR spectroscopy but this compound could not be isolated. Reaction of 1 with LiCH₂SiMe₃ gave a complex mixture, but with LiN(SiMe₃)₂ and LiO-2,6-C₆H₃Me₂ the compounds [Ti(N^tBu){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}X] (X=N(SiMe₃)₂ (4) or O-2,6-C₆H₃Me₂ (5)) were isolated. The X-ray structure of 5 was determined. Reaction of the homologous compound [Ti(N^tBu){Me₃SiNC(Ph)NCH₂CH₂NMe₂}Cl] (6) (containing a 2-carbon atom chain in the pendant arm) with MeLi or PhLi were unsuccessful although the aryloxide compound [Ti(N^tBu){Me₃SiNC(Ph)NCH₂CH₂NMe₂}(O-2,6-C₆H₃Me₂)] (7) could be isolated from the reaction of 6 with LiO-2,6-C₆H₃Me₂. Reaction of the 3-carbon pendant arm arylimido compound [Ti(N-2,6-C₆H₃Me₂){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}Cl] (8) with MeLi afforded thermally sensitive [Ti(N-2,6-C₆H₃Me₂){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}Me] (9), and although the analogous phenyl homologue was elusive, the aryloxide derivative [Ti(N-2,6-C₆H₃Me₂){Me₃SiNC(Ph)NCH₂CH₂CH₂NMe₂}(O-2,6-C₆H₃Me₂)] (10) was successfully isolated and structurally characterised. Comparison of the X-ray structures of 5 and 10 show unexpectedly large differences between the TiNR and TiOAr bond lengths in the two compounds.     

Reaction of 3-dimethylamino-(1,1 -dimethyl) propyl magnesium chloride with tin (IV) and tin (II) chlorides. Stabilization of a SnCl+ cation in the new tin cluster [Me2NCH2CH2C(Me2)SnCl]3 · SnCl2

The reactions of the functional Grignard reagent Me₂ NCH₂CH₂C(Me₂)MgCl (4) with tin tetrachloride, dimethyltin dichloride, and tin (II) chloride are described. From the reactions the compounds bis(3-dimethylamino-1,1-dimethylpropyl) tin dichloride, [Me₂NCH₂CH₂C(Me₂)]₂SnCl₂ (5) , dimethyl(3-dimethylamino-1,1-dimethylpropyl) chlorostannane, Me₂ClSnC(Me₂)CH₂CH₂NMe₂ (6) , 1,1,2,2-tetramethyl-1,2-bis(3-dimethylamino-1,1-dimethylpropyl) distannane,[Me₂SnC(Me₂)CH₂CH₂NMe₂]₂ (7) , 3-dimethylamino-(1,1-dimethyl)propyl tin (II) chloride, Me₂NCH₂CH₂C(Me₂)SnCl (8) , hexakis(3-dimethylamino-1,1-dimethylpropyl) cyclotristannane, {[Me₂NCH₂CH₂C(Me₂)]₂Sn}₃ (9a) , and the tin cluster [Me₂NCH₂CH₂C(Me₂)SnCl]₃ · SnCl₂ (10) have been isolated and characterized by means of multinuclear NMR and Mössbauer spectroscopy, and X-ray diffraction. 10 crystallizes in the trigonal space group P3₁ with the unit cell dimensions a 11.938, c 21.873 Å, V 2699.6 ų Z = 3. The structure was refined to a final R value of 0.064. 10 represents a tetranuclear cluster the skeleton of which is composed out of 4 Sn and a bridging Cl. Formally, the central tin atom is a SnCl⁺ cation stabilized by three stannylene units in a Ψ-trigonal bipyramidal environment. The tin-tin bond lengths are 288.2, 287.3 and 315.6 pm. The intramolecular Sn? N interactions amount to 242.8, 247.4 and 221.0 pm.     

Synthese und Molekülstruktur von Li[(Me2NCH2CH2CH2)4Yb]

Preparation and Structure of Li[(Me₂NCH₂CH₂CH₂)₄Yb] YbCl₃ reacts with dimethylaminopropyl lithium in tetrahydrofuran with formation of Li[(Me₂NCH₂CH₂CH₂)₄Yb]. The X-ray structure determination proves the formation of chelat rings by two of the ligands. The nitrogens of the other two ligands are coordinated to the lithium. The compound crystallizes in the monoclinic space group C2/c with the unit cell parameters a = 27.854(8) Å, b = 9.183(3) Å, c = 20.125(8) Å, β = 96.40° and Z = 8.     

Terminally Dimetallated N,N′‐Dimethylpiperazines with Doubly Spirocyclic Structures

Dilithiated N,N′‐dimethyl‐piperazine, LiCH₂N(CH₂CH₂)₂ NCH₂Li ( 2 ) was prepared by transmetallation of N,N′‐bis(trimethylstannylmethyl)‐piperazine ( 1 ) with ⁿBuLi and was isolated as a highly pyrophoric yellowish powder in high yield. Compound 2 was characterized by elemental analysis and was reacted as difunctional aminomethylating reagent with dialkyl‐earth metal chlorides, R₂MCl (M = Al, Ga; R = Me, ^tBu) which resulted in the formation of spirocyclic adducts of N,N′‐bis(dialkylmetallamethyl)‐piperazine and unreacted dialkylmetal chlorides, [(Me₂AlCl)Me₂AlCH₂N(CH₂CH₂)₂NCH₂AlMe₂(ClAlMe₂)] ( 3 ) and [(^tBu₂GaCl)^tBu₂GaCH₂N(CH₂CH₂)₂NCH₂Ga^tBu₂(ClGa^tBu₂)] ( 4 ) with five‐membered rings. Compounds 1 , 3 and 4 were identified by NMR‐spectroscopy (¹H, ¹³C, ¹¹⁹Sn for 1 , ²⁷Al for 3 ), mass spectra (EI, for 1 ) and by crystal structure determinations.     

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.     

Metal Complexes of Donor-functionalized Fluorinated β-Ketoiminates – Synthesis,Structure, and CVD Application

Six alkali metal complexes of partly-fluorinated, donor-functionalized β-ketoiminate ligands [L¹Li ( 1 ), L¹Na ( 2 ), L¹K ( 3 ), L¹Cs ( 4 ), L¹ = OC(CF₃)CHC(CH₃)NCH₂CH₂OCH₃; L²Li ( 5 ), L²Na ( 6 ), L² = OC(CF₃)CHC(CH₃)NCH₂CH₂N(CH₃)₂] were prepared and structurally characterized. Reactions of L¹Li with PtCl₂ gave the homoleptic Pt complex L¹₂Pt ( 7 ), which was characterized spectroscopically and by single-crystal X-ray diffraction and whose promising application as CVD precursor (chemical vapor deposition) is shown. Polycrystalline, pure Pt films were grown at 500 °C on SiO₂@Si(100) substrates at 10^–3 mbar and characterized by XRD, SEM, AFM, EDX and XPS.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XLIX. Reaktionen von Cerium(IV)-acetylacetonat mit Lithium- und Magnesiumorganylen

Contributions to the Chemistry of Organo Transition Metal Compounds. XLIX. Reactions of Cerium(IV) Acetylacetonate with Organolithium and Organomagnesium Compounds Reacting Ce(acac)₄ with lithium organyls RLi (R = CH₃ 1-Nor¹), ((CH₃)₂NCH₂CH₂CH₂) in the molar ratio 1:1 the cerium compound is reduced with formation of Li[Ce(acac)₄]. Using a molar ratio of Ce:Li = 1:4 organocerium complexes of the composition R₃Ce · 3 Li(acac) or Li₃[R₃Ce(acac)₃] are formed. From reactions with excess CH₃Li (Ce: Li = 1:7) Li₃[Ce(CH₃)₆] · 3 Li(acac) could be isolated. All cerium complexes are characterized by elementary analysis, hydrolysis products, i.r. spectra, and molecular weight determination.     

Five- and six-membered platinacycles derived from phenantryl and anthracenyl imines

The reaction of [Pt₂Me₄(μ-SMe₂)₂] with ligands Me₂NCH₂CH₂NCHAr (2a, Ar=9-phenantryl; 2b, Ar=9-anthracenyl) carried out in acetone at room temperature produced the corresponding compounds [PtMe₂{9-(Me₂NCH₂CH₂NCH)C₁₄H₉}] (3) in which the imines act as bidentate [N,N^′] ligands. Refluxing toluene solutions of compounds 3 gave cyclometallated [C,N,N^′] compounds [PtMe{9-(Me₂NCH₂CH₂NCH)C₁₄H₈}] (4) as a mixture of two isomers containing either a five- or a six-membered metallacycles for 3a and as a single isomer containing a six-membered metallacycle for 3b. The reactions of compounds 4 with acetyl chloride and with methyl iodide produced, respectively, compounds [PtCl{9-(Me₂NCH₂CH₂NCH)C₁₄H₈}] (5) and [PtMe₂I{9-(Me₂NCH₂CH₂NCH)C₁₄H₈}] (6). All compounds were characterised by NMR spectroscopies and analytical data.     

Siloxymethylamines as Aminomethylation Reagents for Amines Leading to Labile Diaminomethanes That can be Trapped as Their [Mo(CO)4] Complexes

Compound Et₃SiOCH₂NMe₂ transfers Me₂NCH₂ to R₂NH (R₂=Et₂, PhMe, [Cr(η⁶‐C₆H₅)(CO)₃]Me, PhH) to form previously unknown diaminomethanes, Me₂NCH₂NR₂ and, in the case of R₂=PhH, the triamine Me₂NCH₂N(Ph)CH₂NMe₂. The diaminomethanes exhibit an unreported disproportionation to a mixture of (R₂N)₂CH₂, (Me₂N)₂CH₂, and Me₂NCH₂NR₂, which can be trapped as their [Mo(CO)₄(diamine)] complexes. Whereas PhMeNCH₂NMe₂ is a labile material, the metal‐substituted ([(η⁶‐C₆H₅)Cr(CO)₃]MeNCH₂NMe₂ is a stable material. The triamine Me₂NCH₂N(Ph)CH₂NMe₂ is unstable with respect to transformation to 1,3,5‐triphenyltriazine, but is readily trapped as the bidentate‐triamineMo(CO)₄. All metal complexes were characterized by single‐crystal X‐ray diffraction.     

Darstellung,Eigenschaften und Konstitution von Bis(dimethylaminopropyl)cadmium und -quecksilber

Synthesis, Properties, and Constitution of Bis(dimethylaminopropyl) Cadmium and Mercury It is reported about synthesis and properties of the bis[3-(N,N-dimethylamino)propyl] compounds of cadmium and mercury. The ¹³C-NMR spectrum of the cadmium compound indicates a spiranoid chelate structure. The concentration dependence of the coupling constants ¹³C? ¹⁹⁹Hg in case of (Me₂NCH₂CH₂CH₂)₂Hg and Me₂NCH₂CH₂CH₂Hg? i-C₄H₉indicates a partial Hg? N interaction.     

Halomethyl-metal compounds : LVII. The insertion of phenyl(bromodichloromethyl)mercury-derived dichlorocarbene into CH bonds. Further studies of the β-metal activated Cz.sbnd;H insertion reaction

Phenyl(bromodichloromethyl)mercury-derived dichlorocarbene inserts into the β CH bonds of Me₃MCH(CH₃)CH₂CH₃ and Me₃MCD(CH₃)CH₂CH₃ (M = Si and Sn) to give Me₃MCH(CH₃)CH(CH₃)CCl₂H and Me₃MCD(CH₃)CH(CH₃)CCl₂H, respectively. That no rearrangement of deuterium to the β position occured was suggested by the ¹³C and ¹H NMR spectra of the products. This result is taken to speak against the intervention of sila- and stannacyclopropenium ion intermediates in the insertion process and in favor of stabilization of the transition state of the insertion reaction by metalcarbon bond hyperconjugation (σ-π stabilization, a vertical stabilization process).     

Über Bildung und Reaktionen der CH2Li‐Derivate von tBu2P–P=P(CH3)tBu2 und (Me3Si)tBuP–P=P(CH3)tBu2

Formation and Reactions of the CH₂Li‐Derivatives of ^tBu₂P–P=P(CH₃)^tBu₂ and (Me₃Si)^tBuP–P=P(CH₃)^tBu₂ With ⁿBuLi, (Me₃Si)^tBuP–P=P(CH₃)^tBu₂ ( 1 ) and ^tBu₂P–P=P(CH₃)^tBu₂ ( 2 ) yield (Me₃Si)^tBuP–P=P(CH₂Li)^tBu₂ ( 3 ) and ^tBu₂P–P=P(CH₂Li)^tBu₂ ( 4 ), wich react with Me₃SiCl to give (Me₃Si)^tBuP–P=P(CH₂–SiMe₃)^tBu₂ ( 5 ) and ^tBu₂P–P=P(CH₂–SiMe₃)^tBu₂ ( 6 ), respectively. With ^tBu₂P–P(SiMe₃)–P^tBuCl ( 7 ), compound 3 forms 5 as well as the cyclic products [H₂C–P(^tBu)₂=P–P(^tBu)–P^tBu] ( 8 ) and [H₂C–P(^tBu)₂=P–P(P^tBu₂)–P(^tBu)] ( 9 ). Also 3 forms 8 with ^tBuPCl₂. The cleavage of the Me₃Si–P‐bond in 1 by means of C₂Cl₆ or N‐bromo‐succinimide yields (Cl)^tBuP–P=P(CH₃)^tBu₂ ( 10 ) or (Br)^tBuP–P=P(CH₃)^tBu₂ ( 11 ), resp. With LiP(SiMe₃)₂, 10 forms (Me₃Si)₂P–P(^tBu)–P=P(CH₃)^tBu₂ ( 12 ), and Et₂P–P(^tBu)–P=P(CH₃)^tBu₂ ( 13 ) with LiPEt₂. All compounds are characterized by ³¹P NMR Data and mass spectra; the ylide 5 and the THF adduct of 4 additionally by X‐ray structure analyses.     

Chemistry of N,N-Dimethylaminoalkylchalcogenolate Complexes of Palladium(II) and Platinum(II)

Abstract

Four different series of N,N-dimethylaminoalkylchalcogenolates, viz. Me₂NCH₂ CH₂E^?, Me₂NCH(Me)CH₂E^?, Me₂NCH₂CH(Me)E^?, and Me₂NCH₂CH₂CH₂E^? (E = S, Se, Te), (referred as E^∩N) have been synthesized and characterized. Their reactions with palladium(II) and platinum(II) precursors have been explored. Complexes of the general formula, [MCl(E^∩N)]_n, [MCl(E^∩N)₂]_n, [MCl(E^∩N)(PR₃)], [M₂Cl₂(μ-E^∩N)₂(PR₃)₂], [M₂(μ-E^∩N)₂(P^∩P)₂]²⁺, etc. have been isolated. All the complexes have been characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹²⁵Te, ¹⁹⁵Pt), UV-vis, and FAB mass spectral data. A weak absorption in the electronic spectra of [MCl(E^∩N)(PR₃)] has been attributed to metal mediated ligand-to-ligand charge transfer and showed pronounced chalcogen dependence being red shifted on moving from S → Se → Te. Structures of several complexes have been established by X-ray diffraction analyses. Thermal behavior of some of these complexes has been investigated by TGA.     

X-ray crystallographic and solution studies of the pentamethyldiethylenetriamine and tetramethylethylenediamine adducts of lithium diphenylphosphide

X-ray crystallographic studies on the lithium diphenylphosphide adducts (Me₂NCH₂CH₂)₂NMe₂ · LiPPh₂ (1) and Me₂NCH₂CH₂NMe₂ · LiPPh₂ (2) are reported.1 is monomeric, with a terminal PPh₂ unit containing a pyramidally coordinated phosphorus atom attached to the four-coordinate metal atom by a Li-P bond of length 2.567(6)Å.2 crystallizes as dimers, (Me₂NCH₂CH₂NMe₂ · LiPPh₂)₂, with bridging PPh₂ units containing (distorted) tetrahedrally coordinated phosphorus atoms: their planar (LiP)₂ rings are roughly square-shaped (mean PLiP angle 91°, mean LiP distance 2.61Å). Discussion of features of these structures is facilitated by ab initio MO calculations on the model systems LiPH₂ and (LiPH₂)₂. Cryoscopic molecular mass measurements and high-field⁷Li/³¹P NMR spectroscopic studies on solutions of1 and2 indicate that both solid-state structures are retained in arene solution, though some dissociation of2 into monomers is apparent.     

Effect of the Structure of Phase-Transfer Catalyst on the Rate of Alkaline Hydrolysis of N-Benzyloxycarbonylglycine 4-Nitrophenyl Ester in the System Chloroform-Borate Buffer

Onium salts QZ (Z = Cl, Br) having a lipophilic (Q = R₃NR', where R' = C₁₆H₃₃) or readily extractable (into organic phase) cation (Q = Ph₄P) exhibit a high catalytic activity in phase-transfer alkaline hydrolysis of N-benzyloxycarbonylglycine 4-nitrophenyl ester in the two-phase system chloroform-borate buffer (pH 10). No catalytic effect is observed in the presence of hydrophilic ammonium salts [Et₄NCl, Et₃PhCH₂NCl, Me₂(NH₂)+NCH₂CH₂+N(NH₂)Me₂·2Br^-] and those insoluble in organic solvents [(Me)₃+NNH(CH₂)₂COO^-·2H₂O, Me₂(NH₂)+NCH₂CO^-, Me₂(NH₂)+N(CH₂)₃SO₃ ^-]. These data suggest extraction mechanism of the process. The activity of lipophilic cation Q is determined mainly by two factors: its extractibility, on the one hand, and the ability to form micelles, on the other.     

α-Heteroatom-substituted carbanions: the structure of {(Me2NCH2CH2NMe2)Li[(PMe2)CH(SiMe3)]}2, an unsual organolithium dimer

The effect of silyl substitution at the carbanionoid C atoms on structure and bonding of lithium-phosphinomethanides has been investigated by determination of the structure of {(Me₂NCH₂CH₂NMe₂)Li[(PMe₂)CH(SiMe₃)]}₂, which has a six-membered ring (PCLi)₂ in twist conformation, and so is markedly different in structure from both the bis-silyl substituted as well as the unsubstituted analogue.     

Hypercoordinated diorganoantimony(III) compounds of types [2-(Me2NCH2)C6H4]2SbL and [PhCH2N(CH2C6H4)2]SbL (L = Cl,ONO2, OSO2CF3). Synthesis,structure and catalytic behaviour in the Henry reaction

The compounds [2-(Me₂NCH₂)C₆H₄]₂SbL (L = ONO₂ ( 2 ), OSO₂CF₃ ( 3 )) and [PhCH₂N(CH₂C₆H₄)₂]SbL (L = ONO₂ ( 5 ), OSO₂CF₃ ( 6 )) were prepared by reacting [2-(Me₂NCH₂)C₆H₄]₂SbCl ( 1 ) and [PhCH₂N(CH₂C₆H₄)₂]SbCl ( 4 ), respectively, with the appropriate silver(I) salt in a 1:1 molar ratio. The new species 2 – 6 were structurally characterized in solution using multinuclear NMR and in the solid state using infrared spectroscopy. The solid-state structures for compounds 2 , 4 and 6, as well as for the hydrolysis ionic product [{2-(Me₂N⁺HCH₂)C₆H₄}{2-(Me₂NCH₂)C₆H₄}SbOH][CF₃SO₃]⁻ ( 3h ) were determined using single-crystal X-ray diffraction. Medium to strong intramolecular N→ Sb interactions were observed in all these four compounds, thus resulting in hypercoordinated organoantimony(III) species 14-Sb-6 in 2 and 10-Sb-4 in the cation of 3h and in 4 and 6 . Compounds 1 – 6 and the starting amines PhCH₂NMe₂ and PhCH₂N(CH₂C₆H₄Br-2)₂ were investigated as catalysts in the Henry (nitroaldol) addition of nitromethane to benzaldehyde. The activity of compounds 1 – 6 resulted as an effect of the cooperation of the positively charged antimony with the negatively charged nitrogen.     

Koordinationschemische Untersuchungen an Zinkdialkylen. XIV. Über Lithium- und Zink-3-(N,N-dialkylamino)-propyl-Verbindungen

Investigations on the Coordination Chemistry of Zinc Dialkyls. XIV. On Lithium and Zinc 3(N, N-Dialkylamino)propyl Compounds It is reported on synthesis and properties of organo lithium compounds of the type [R₂NCH₂CH₂CH₂Li]_n. The structure is proposed by reason of molecular weight determination and ¹³C-NMR spectra. In dependence of the molar ratio the lithium dialkylamino propyls and the corresponding Grignard reagents react with zinc chloride forming dimer alkyl zinc chlorides [R₂NCH₂CH₂CH₂ZnCl]₂ or monomer spiranoide chelate complexes of the formula [R₂NCH₂CH₂CH₂]₂Zn (R = CH₃, C₂H₅).     

Organoselenium compounds containing pyrazole or phenylthiazole groups: Synthesis,structure, tin(IV) complexes and antiproliferative activity

The diorganodiselenides (pzCH₂CH₂)₂Se₂ ( 1 ) and (PhtzCH₂)₂Se₂ ( 2 ) were prepared by reacting Na₂Se₂ with 1‐(2‐bromoethyl)‐1H‐pyrazole and 4‐(chloromethyl)‐2‐phenylthiazole, respectively, while the reactions between 1‐(2‐bromoethyl)‐1H‐pyrazole or 4‐(chloromethyl)‐2‐phenylthiazole and the lithium organoselenolates [2‐(Et₂NCH₂)C₆H₄]SeLi and [2‐{O(CH₂CH₂)₂NCH₂}C₆H₄]SeLi in a 1:1 molar ratio resulted in the heteroleptic diorganoselenium(II) compounds [2‐(Et₂NCH₂)C₆H₄](R)Se (R = pzCH₂CH₂ ( 3 ) or PhtzCH₂ ( 5 )) and [2‐{O(CH₂CH₂)₂NCH₂}C₆H₄](R)Se (R = pzCH₂CH₂ ( 4 ) or PhtzCH₂ ( 6 )). The diorganotin(IV) bis(organoselenolato) derivatives of type R₂Sn(SeCH₂CH₂pz)₂ (R = 2‐(Me₂NCH₂)C₆H₄ ( 7 ) or Me ( 8 )) were obtained by reacting (pzCH₂CH₂)SeNa with the appropriate diorganotin(IV)dichloride in a 2:1 molar ratio. All compounds were investigated using NMR spectroscopy (¹H, ¹³C, ⁷⁷Se, ¹¹⁹Sn as appropriate) and ESI+ mass spectrometry. The molecular structures of 2 and 6 were determined using single‐crystal X‐ray diffraction. The formation of a 10–Se–3 hypercoordinated species was evidenced for 6 in the solid state, as a consequence of the C,N coordination behaviour of the 2‐{O(CH₂CH₂)₂NCH₂}C₆H₄ group. Compounds 1 , 7 and 8 were investigated for their antiproliferative activity towards the mouse colon carcinoma C26 cell line with the preliminary results showing a better activity than 5‐fluorouracil.     

Nucleophilic Attack at Pentaarsaferrocene [Cp*Fe(η5-As5)]—The Way to Larger Polyarsenide Ligands

By the reaction of [Cp*Fe(η⁵-As₅)] ( I ) (Cp*=C₅Me₅) with main group nucleophiles, unique functionalized products with η⁴-coordinated polyarsenide (As_n) units (n=5, 6, 20) are obtained. With carbon-based nucleophiles such as MeLi or KBn (Bn=CH₂Ph), the anionic organo-substituted polyarsenide complexes, [Li(2.2.2-cryptand)][Cp*Fe(η⁴-As₅Me)] ( 1 a ) and [K(2.2.2-cryptand)][Cp*Fe{η⁴-As₅(CH₂Ph)}] ( 1 b ), are accessible. The use of KAsPh₂ leads to a selective and controlled extension of the As₅ unit and the formation of the monoanionic compound [K(2.2.2-cryptand][Cp*Fe(η⁴-As₆Ph₂)] ( 2 ). When I is reacted with [M]As(SiMe₃)₂ (M=Li ⋅ THF; K), the formation of the largest known anionic polyarsenide unit in [M′(2.2.2-cryptand)]₂[(Cp*Fe)₄{μ₅-η⁴:η⁴:η³:η³:η¹:η¹-As₂₀}] ( 3 ) occurred (M′=Li ( 3 a ), K ( 3 b )).