A 19F NMR study of the transmission of electronic effects in triarylantimony and triarylbismuth compounds. A comparison with the nitrogen- and carbon-containing analogues

A ¹⁹F NMR study of the transmission of electronic effects has been made for the systems Ar₂EC₆H₄F-4 (E = Sb, Bi, CH, N). The fluorine chemical shifts obtained are correlated with the polar constants (Σσ^o and Σσ) of the substituents, suggesting that electronic effects are transmitted through the SbC_ar, BiC_ar and CC_ar bonds predominantly by an inductive mechanism, whereas the transmission through the NC_ar bonds is contributed to significantly by classical resonance effects due to competitive conjugation of the lone pair with the aromatic rings, and the substituents therein. A dual parameter correlation of the fluorine chemical shifts with the inductive (σ_I) and resonance (σ^o_R and σ_R) parameters of the substituents in the aromatic rings has led to similar conclusions. The inductive transmission through the bridging Sb and Bi atoms has been assigned to the absence of conjugation of lone pair and vacant d-orbitals of the metals with π-electron systems of the aromatic rings. On the basis of the values of the ? coefficients for the correlation equations obtained it has been established that the transmitting ability of the BiC_ar bonds is close to that of the C_alC_ar bonds and considerably lower than the transmitting ability of the NC_ar bonds.     

1,4-Phenylen-bis-diphenylderivate der Elemente der 5. Hauptgruppe des Periodensystems

Zusammenfassung Die Darstellung sämtlicher am mittleren Benzolkern p-substitutierten Verbindungen (C₆H₅)₂ MC₆H₄ M(C₆H₅)₂ mitM=N, P, As, Sb und Bi wird beschrieben. Für die bereits bekannte Stickstoff-bzw. Arsen-Verbindung konnte ein neuer Darstellungs-weg mit guten Ausbeuten gefunden werden, während die Antimon-und Wismutverbindung erstmals beschrieben werden. Durch Dipolmomentmessungen, UV- und IR-Aufnahmen ist ein Vergleich mit den einfachen Triphenylderivaten der genannten Elemente möglich.

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The compounds p-(C₆H₅)₂ MC₆H₄ M(C₆H₅)₂,M=N, P, As, Sb, and Bi, were prepared. New methods for the preparation of the N and As compound with good yields were found. The Sb and Bi compound were synthesized for the first time. Dipole moments, IR- and UV-spectra of these compounds were compared with those of the triphenyl derivates.

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Herrn Prof. Dr.F. Wessely zum 70. Geburtstag gewidmet.     

Heavy Carbene Analogues: Donor‐Free Bismuthenium and Stibenium Ions

Kinetically stabilized congeners of carbenes, R₂C, possessing six valence electrons (four bonding electrons and two non‐bonding electrons) have been restricted to Group 14 elements, R₂E (E=Si, Ge, Sn, Pb; R=alkyl or aryl) whereas isoelectronic Group 15 cations, divalent species of type [R₂E]⁺ (E=P, As, Sb, Bi; R=alkyl or aryl), were unknown. Herein, we report the first two examples, namely the bismuthenium ion [(2,6‐Mes₂C₆H₃)₂Bi][BAr^F₄] ( 1 ; Mes=2,4,6‐Me₃C₆H₂, Ar^F=3,5‐(CF₃)₂C₆H₃) and the stibenium ion [(2,6‐Mes₂C₆H₃)₂Sb][B(C₆F₅)₄] ( 2 ), which were obtained by using a combination of bulky meta‐terphenyl substituents and weakly coordinating anions.     

Synthesis and Structure of (N,)C,N‐chelated Organoantimony(III) and Bismuth(III) Cations and Isolation of Their Adducts with Ag[CB11H12]

The treatment of N,C,N‐chelated antimony(III) and bismuth(III) chlorides [C₆H₃‐2,6‐(CH=NR)₂]MCl₂ [R = tBu and M = Sb ( 1 ) or Bi ( 2 ); R = Dmp and M = Sb ( 3 ) or Bi ( 4 )] (Dmp = 2,6‐Me₂C₆H₃) with one molar equivalent of Ag[CB₁₁H₁₂] led to a smooth formation of corresponding ionic pairs {[C₆H₃‐2,6‐(CH=NR)₂]MCl}⁺[CB₁₁H₁₂]^– [R = tBu and M = Sb ( 7 ) or Bi ( 8 ), R = Dmp and M = Sb ( 9 ) or Bi ( 10 )]. Similarly, the reaction of C,N‐chelated analogues [C₆H₂‐2‐(CH=NDip)‐4,6‐(tBu)₂]MCl₂ [M = Sb ( 5 ) or Bi ( 6 ), Dip = 2′,6′‐iPr₂C₆H₃] gave compounds {[C₆H₂‐2‐(CH=NDip)‐4,6‐(tBu)₂]MCl}⁺[CB₁₁H₁₂]^– [M = Sb ( 11 ) or Bi ( 12 )]. All compounds 7 – 12 were characterized with ¹H, ¹¹B and ¹³C{¹H} NMR spectroscopy, ESI‐mass spectrometry, IR spectroscopy, and molecular structures of 7 – 9 and 12 were determined by the help of single‐crystal X‐ray diffraction analysis. In contrast, all attempts to cleave also the second M–Cl bond in 7 – 12 using another molar equivalent Ag[CB₁₁H₁₂] remained unsuccessful. Nevertheless, the reaction between 7 (or 8 ) and Ag[CB₁₁H₁₂] produced unprecedented adducts of both reagents namely {[C₆H₃‐2,6‐(CH=NtBu)₂]SbCl}₂²⁺[Ag₂(CB₁₁H₁₂)₄]^2– ( 13 ) and {[C₆H₃‐2,6‐(CH=NtBu)₂]BiCl}⁺[Ag(CB₁₁H₁₂)₂]^– ( 14 ) in a reproducible manner. The molecular structures of these sparingly soluble compounds were determined by single‐crystal X‐ray diffraction analysis.     

Mono- and bisphenoxy derivatives of bis(indenyl) titanium(IV)

A series of (C₉H₇)₂Ti(OAr)Cl and (C₉H₇)₂Ti(OAr)₂ complexes whereAr=C₆H₅,p-ClC₆H₄, α-C₁₀H₇ or β-C₁₀H₇, have been synthesised by the reaction of bis(indenyl) titanium(IV) dichloride with an appropriate phenol in a 1:1 and 1:2 molar ratio in refluxing benzene in the presence of triethylamine. The new derivatives have been characterized on the basis of their elemental analyses, conductance measurements and spectral (IR,¹H-NMR and electronic) studies.     

Antimon-organo-Verbindungen. VI. Kristallines „Phenylantimon”︁ Bildung und Spaltung mit Natrium bzw. Lithiumbutyl

Organoantimony Compounds. VI. Crystalline Phenyl Antimony. Formation and Cleavage with Sodium and Lithium Butyl, respectively Reactions of C₆H₅SbH₂ with C₆H₅CH ? CH₂, C₆H₅C ? CH and other unsaturated compounds give the corresponding hydrogenated system and phenyl antimony as orange-red crystals and the formula (C₆H₅Sb)₆ · 1 C₆H₆ 1.1 reacts with sodium by cleavage of Sb–Sb bonds forming C₆H₅SbNa₂ and C₆H₅(Na)Sb–Sb(Na)C₆H₅. These stibides are suitable materials to prepare tert. stibines, distibines and cyclic stibines. The cleavage of 1 with butyllithium is a complicated reaction and gives beside other stibides also C₆H₅(C₄H₉)SbLi which can be characterized as (CH₃)₃Si–Sb(C₄H₉)C₆H₅. The ¹H-nmr data of the prepared stibines are discussed.     

Oligoorganogermanes: Interplay between Aryl and Trimethylsilyl Substituents

Derivatives of main group elements containing element–element bonds are characterized by unique properties due to σ-conjugation, which is an attractive subject for investigation. A novel series of digermanes, Ar₃Ge-Ge(SiMe₃)₃, containing aryl (Ar = p-C₆H₄Me (1), p-C₆H₄F (2), C₆F₅ (3)) and trimethylsilyl substituents, was synthesized by the reaction of germyl potassium salt, [(Me₃Si)₃GeK*THF], with triarylchlorogermanes, Ar₃GeCl. The optical and electronic properties of such substituted oligoorganogermanes were investigated spectroscopically by UV/vis absorption spectroscopy and theoretically by DFT calculations. The molecular structures of compounds 1 and 2 were studied by XRD analysis. Conjugation between all structural fragments (Ge-Ge, Ge-Si, Ge-Ar, where Ar is an electron-donating or withdrawing group) was found to affect the properties.     

Synthesis and structures of the six-coordinate donor-acceptor complexes R3(C6H4O2)Sb…L (R=Ph, L=OSMe2 or ONC5H5; R=Me, L=ONC5H5 or NC5H5) and R3(C2H4O2)Sb…L (R=Ph, L=ONC5H5; R=Cl or C6F5, L=OPPh3)

One-pot oxidation of R₃Sb (R=Ph, Me, Cl, or C₆F₅) withtert-butyl hydroperoxide in the presence of 1,2-diols and monodentate donor compounds was studied. The structures of the resulting neutral organic donor-acceptor Sb^V complexes, Ph₃(C₆H₄O₂)Sb…OSMe₂, Ph₃(C₆H₄O₂)Sb…ONC₅H₅, Me₃(C₆H₄O₂)Sb…ONC₅H₅, Me₃(C₆H₄O₂)Sb…NC₅H₅, Ph₃(C₂H₄O₂)Sb…ONC₅H₅, and Cl(C₆F₅)₂(C₂H₄O₂)Sb…OPPh₃, were established by X-ray diffraction analysis. In these complexes, the coordination environment about the Sb atoms is a distorted octahedron. The Sb?O(N) distances and the Sb?O?E angles (E=S, N, or P) vary over wide ranges.     

Preparation and properties of new ferrocenyl heterobimetallic complexes with counterion dependent NLO responses

New ferrocenyl-based bimetallic cationic compounds of the type of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]X (X=PF₆, BF₄) and of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNFeCp(CO)₂]PF₆ have been obtained and characterized. The crystal structure of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]BF₄ has been established by means of X-ray diffractometry. The NLO responses of the compounds have been studied by the hyper-Rayleigh scattering technique and the hyperpolarizability is found to be dependent on the nature of the counterion.     

Organo group VB chemistry: Part VI. On the electric dipole moments of some substituted tertiary phenylphosphines, -arsines, -stibines and -bismuthines

The dipole moments of the following series of tertiary substituted aryl-group VB compounds were measured: (a) (C₆H₅)₃M and (XC₆H₄)₃M with M = P, As, Sb, Bi and X = 4-F, 4-Cl, 4-CH₃, 3-F, 3-Cl; and (b) (3-XC₆H₄)_3?n PR_n with R = C₆H₅, 4-FC₆H₄ and X = F, Cl. These experimental molecular moments are discussed as a consistent set of data that allows the calculation, within the framework of the vectorial additive method, of suitable group moments, bond moments and configurational parameters.     

Synthesis of organoantimony(V) and μ-oxy-bis(triarylantimony) selenocyanates using a phase-transfer catalyst

Several new, pentacoordinated, triorganoantimony bis-selenocyanates [R₃Sb(SeCN)₂ (R = Me, Ph, p-CH₃C₆H₄, p-ClC₆H₄, p-F-C₆H₄ or C₆F₅)], tetraorganostibonium selenocyanates [R₃R′Sb(SeCN) (R = R′ = Ph; R = Ph, and R′ = CH₂CHCH₂)] and μ-oxy-bis(triarylantimony) bis-selenocyanates {[Ar₃SbOSbAr₃](SeCN)₂ (Ar = Ph, p-CH₃C₆H₄, p-ClC₆H₄ or p-FC₆H₄)} have been synthesized from potassium selenocyanate and the corresponding organoantimony halide (chloride and/or bromide) in the presence of the phase-transfer catalyst 18-crown-6, and characterized. Spectroscopic evidence suggested an iso structure (Sb—NCSe). The compounds were also obtained in the absence of 18-crown-6 but in lower yields. Some of these compounds were found to exhibit a significant biological activity.     

From Dibismuthenes to Three‐ and Two‐Coordinated Bismuthinidenes by Fine Ligand Tuning: Evidence for Aromatic BiC3N Rings through a Combined Experimental and Theoretical Study

The reduction of N,C,N‐chelated bismuth chlorides [C₆H₃‐2,6‐(CH?NR)₂]BiCl₂ [where R=tBu ( 1 ), 2′,6′‐Me₂C₆H₃ ( 2 ), or 4′‐Me₂NC₆H₄ ( 3 )] or N,C‐chelated analogues [C₆H₂‐2‐(CH?N‐2′,6′‐iPr₂C₆H₃)‐4,6‐(tBu)₂]BiCl₂ ( 4 ) and [C₆H₂‐2‐(CH₂NEt₂)‐4,6‐(tBu)₂]BiCl₂ ( 5 ) is reported. Reduction of compounds 1 – 3 gave monomeric N,C,N‐chelated bismuthinidenes [C₆H₃‐2,6‐(CH?NR)₂]Bi [where R=tBu ( 6 ), 2′,6′‐Me₂C₆H₃ ( 7 ) or 4′‐Me₂NC₆H₄ ( 8 )]. Similarly, the reduction of 4 led to the isolation of the compound [C₆H₂‐2‐(CH?N‐2′,6′‐iPr₂C₆H₃)‐4,6‐(tBu)₂]Bi ( 9 ) as an unprecedented two‐coordinated bismuthinidene that has been structurally characterized. In contrast, the dibismuthene {[C₆H₂‐2‐(CH₂NEt₂)‐4,6‐(tBu)₂]Bi}₂ ( 10 ) was obtained by the reduction of 5 . Compounds 6 – 10 were characterized by using ¹H and ¹³C NMR spectroscopy and their structures, except for 7 , were determined with the help of single‐crystal X‐ray diffraction analysis. It is clear that the structure of the reduced products (bismuthinidene versus dibismuthene) is ligand‐dependent and particularly influenced by the strength of the N→Bi intramolecular interaction(s). Therefore, a theoretical survey describing the bonding situation in the studied compounds and related bismuth(I) systems is included. Importantly, we found that the C₃NBi chelating ring in the two‐coordinated bismuthinidene 9 exhibits significant aromatic character by delocalization of the bismuth lone pair.     

Synthesis and some reactions of tris (pentafluorophenyl) antimony compounds

(C₆F₅)₃Sb has been found to react with interhalogens and halo-pseudohalogens, IX(X = Cl, Br, N₃ and NCO), pseudohalogen (SCN), and elemental sulphur to give oxidative addition products (I–VI). (C₆F₅)₃SbS(VI) may also be prepared by the reaction of (C₆F₅)₃SbCl₂ with H₂S. Metathetical reactions of (C₆F₅)₃SbCl₂ with appropriate metallic salts yield covalent pentacoordinate disubstituted products (V, VII–XII) of the general formula, (C₆F₅)₃SbY₂ (Y = NCS, NCO, ?ONCMe₂, ?ONCMePh $\text{?NCO(CH}{}_2\text{)}{}_2\text{C}$O and p-NO₂C₆H₄OCO). Treatment of (C₆F₅)₃SbCl₂ with aqueous NaN₃ gives the binuclear oxo-bridge compound, [(C₆F₅)₃SbOSb(C₆F₅)₃](N₃)₂·(III) and (IV) are also accessible by displacement reaction of (I) or (II) with the corresponding metallic salt. Molecular weight, conductance measurements, and IR spectra on the new organoantimony(V) derivatives have been obtained.Reductive cleavage reactions of (C₆F₅)₃SbS with hexaaryldileads, Ar₆Pb₂(Ar = Phenyl, p-tolyl) produce (C₆F₅)₃Sb and the corresponding bis(triaryllead) sulphide but treatment of (C₆F₅)₃SbX₂(X = NCO, Cl) with Ar₆Pb₂ gave Ar₄Pb and Ar₂PbX₂ together with (C₆F₅)₃Sb.(C₆F₅)₃SbCl₂ and bis(triorganotin)sulphides undergo exchange of anionic groups.     

N-aryl-and N-vinyldiaza-18-crown-6: Synthesis and complexing ability

The nucleophilic aromatic and vinyl substitution using diaza-18-crown-6 as nucleophile afforded a number of its N,N’-diaryl-[aryl = 2,4-(NO₂)₂C₆H₃, 4-C₅F₄N, 4-CF₃C₆F₄] and N,N’-dialkenyl-substituted derivatives [alkenyl = PhC(O)CH=CH, MeOCOCH=CH, (EtO₂C)₂C=C(Ph), etc.]. Arylation of diaza-18-crown-6 with nonactivated aryl bromides, such as 4-Me₂NC₆H₄Br, 4-MeOC₆H₄Br, C₆H₅Br, and 4-CF₃C₆H₄Br, was effected under catalysis by palladium complexes. N,N’-Diaryldiaza-18-crowns-6 having electron-acceptor substituents in the aromatic rings turned out to be incapable of forming complexes with metal cations, while their analogs containing electron-donor para-methoxy and para-dimethylamino groups gave complexes with barium perchlorate.     

Synthesis of potential antimalarials

A series of quinoline derivatives containing a 2-thienyl ring in the 2-position and CO₂H, CH₂OH, CHO, CH(OH)CN, CH(OH)CO₂H, CO₂C₂H₅, COCH[N(C₂H₅)₂]CO₂C₂H₅, COCH₂N(C₂H₅)₂, COCH₃, substituents in the 4-position was synthesized. Both intermediate and target compounds were tested for antimalarial activity. A second series with a 5-bromo-2-thienyl group in the 2-position and CHOHCH₂N(C₂H₅)₂, CHOHCH₂N(CH₂)₆, and CHOHCH₂N(CH₂C₆H₅)₂ substituents in the 4-position was also prepared, it was found that, although these quinoline methanols were moderately active antimalarials, they exhibited a high degree of phototoxicity. A third series of compounds with 2-alkyl substituents (methyl, t-butyl) was also synthesized, and these were found to combine a modest degree of antimalarial activity with low phototoxicity. Several novel synthetic routes to the above compounds were developed and are detailed.     

Triorganoantimon- und Triorganobismutderivate von 2-Pyridincarbonsäure und 2-Pyridylessigsäure Kristall- und Molekülstrukturen von (C6H5)3Sb(O2C-2-C5H4N)2 und (CH3)3Sb(O2CCH2-2-C5H4N)2

Triorganoantimony and Triorganobismuth Derivatives of 2-Pyridinecarboxylic Acid and 2-Pyridylacetic Acid. Crystal and Molecular Structures of (C₆H₅)₃Sb(O₂C-2-C₅H₄N)₂ and (CH₃)₃Sb(O₂CCH₂-2-C₅H₄N)₂ Triorganoantimony and triorganobismuth dicarboxylates R₃M(O₂C-2-C₅H₄N)₂ (M = Sb, R = CH₃, C₆H₅, 4-CH₃OC₆H₄; M = Bi, R = C₆H₅, 4-CH₃C₆H₄) and (CH₃)₃Sb(O₂CCH₂-2-C₅H₄N)₂ have been prepared from (CH₃)₃Sb(OH)₂, R₃SbO (R = C₆H₅, 4-CH₃OC₆H₄), or R₃BiCO₃ (R = C₆H₅, 4-CH₃C₆H₄) and the appropriate heterocyclic carboxylic acid. Vibrational spectroscopic data indicate a trigonal bipyramidal environment of M the O(? C)-atoms of the carboxylate ligands being in the apical and three C atoms (of R) in the equatorial positions; in addition coordinative interaction occurs in the 2-pyridinecarboxylates between M and O(?C) of one and N of the other carboxylate ligand and in (CH₃)₃)Sb(O₂CCH₂-2-C₅H₄N)₂ between Sb and O(?C) of both carboxylate ligands. (C₆H₅)₃Sb(O₂C-2-C₅H₄N)₂/(CH₃)₃Sb(O₂CCH₂-2-C₅H₄N)₂ crystallize monoclinic [space group P2₁/c/P2₁/n; a = 892.6(9)/1043.4(6), b = 1326.9(6)/3166.2(18), c = 2233.1(9)/1147.5(7) pm, β = 99.74(8)°/97.67(5)° Z = 4/8; d(calc.) = 1.522/1.553 × Mg m^?3; V_cell = 2606.7 × 10⁶/3757.0 × 10⁶pm³, structure determination from 3798/4965 independent reflexions (F ≥ 4.0 σ(F))/(I ≥ 1.96 σ(I), R(unweighted) = 0.024/0.036]. Sb is bonding to three C₆H₅/CH₃ groups in the equatorial plane [mean distances Sb? C: 212.2(3)/208.7(6) pm] and two carboxylate ligands via O in the apical positions [Sb? O distances: 218.5(2), 209.9(2)/212.1(3), 213.2(3) pm]. In (C₆H₅)₃Sb(O₂C-2-C₅H₄N)₂ there is a short Sb? O(?C) and a short Sb? N contact [Sb? O: 272.1(2), Sb? N: 260.2(2) pm] and distoritions of the equatorial angles [C? Sb? C: 99.2(1)°, 158.2(1)°, 102.0(1).] and of the axial angle [O? Sb? O: 169.9(1)°], and in (CH₃)₃Sb(O₂CCH₂-2-C₅H₄N)₂, which contains two different molecules in the asym-metric unit, there are two Sb? O(?C) contacts [Sb? O, mean: 302.2(4), and 310.7(4)pm, respectively] and distortions of the equatorial angles [C? Sb? C: 114.5(2)°, 132.4(3)° 113.1(2)°, and 123.9(3)° 115.5(2)°, 120.6(3)°, respectively] and of the axial angles [O? Sb? O: 174,9(1)°, 177.9(1)°, respectively].     

Tetraphenyl-and tetratolylantimony complexes with N,N-dialkyldithiocarbamate ligands: Synthesis, X-ray diffraction analysis, and 13C and 15N CP/MAS NMR studies

Crystalline tetraphenylantimony and tetratolylantimony complexes with N,N-dialkyldithiocarbamate ligands [Sb(C₆H₅)₄(S₂CNR₂)] (R = CH₃, C₂H₅, and C₃H₇ and R₂ = (CH₂)₆) were synthesized by ligand exchange reactions and studied by ¹³C and ¹⁵N CP/MAS NMR spectroscopy. X-ray diffraction analysis revealed that the complex [Sb(n-CH₃-C₆H₄)₄{S₂CN(C₃H₇)₂}] exists as the single molecular form, while [Sb(C₆H₅)₄{S₂CN(CH₂)₆}] exists as two molecular conformers. The ¹³C and ¹⁵N signals were assigned to the positions of the atoms in the isomeric structures [Sb(C₆H₅)₄{S₂CN(CH₂)₆}] in terms of different degrees of double bonding in the formally single =N-C(S)S-bond.     

Substituent effects in the 13C NMR chemical shifts of para-(para-substituted benzylidene amino)benzonitrile and para-(ortho-substituted benzylidene amino)benzonitrile

¹³C NMR chemical shifts were measured in CDCl₃ for two series of substituted benzylidene anilines. The substituted benzylidene anilines p-X-C₆H₄CH=NC₆H₄-p-CN p-X-C₆H₄CH=NC₆H₄-o-CN (X = NO₂, F, Cl, Br, H, Me, MeO, NMe₂). The substituent dependence of δC(C=N) was used as a tool to study electronic substituent effects on the azomethine unit. The benzylidene substituents X have a reverse effect on δC(C=N): electron-withdrawing substituents cause shielding, while electrondonating ones do the reverse, the resonance effects clearly predominating over the inductive effects. Additionally, the presence of a specific cross-interaction between X and C=N could be verified. The electronic effects of the neighboring aromatic ring substituents systematically modify the sensitivity of the C=N group to the electronic effects of the benzylidene substituents. These results can be rationalized in terms of the substituent-sensitive balance of the electron delocalization (mesomeric effects).     

Palladium(II) compounds with planar chirality. X-Ray crystal structures of (+)-(R)-[{(η5-C5H4)–CHN–CH(Me)–C10H7}Fe(η5-C5H5)] and (+)-(Rp,R)-[Pd{[(Et–CC–Et)2(η5-C5H3)–CHN–CH(Me)–C10H7]Fe(η5-C5H5)}Cl]

A wide variety of planar chiral cyclopalladated compounds of general formulae [Pd{[(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl(L)] (with L=py-d₅ or PPh₃), [Pd{[(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}(acac)] or [Pd{[(R¹–CC–R²)₂(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl] (with R¹=R²=Et; R¹=Me, R²=Ph; R¹=H, R²=Ph; R¹=R²=Ph; R¹=R²=CO₂Me or R¹=CO₂Et, R²=Ph) are reported. The diastereomers {(R_p,R) and (S_p,R)} of these compounds have been isolated by either column chromatography or fractional crystallization. The free ligand (R)-(+)-[{(η⁵-C₅H₄)–CHN–CH(Me)–C₁₀H₇}Fe(η⁵–C₅H₅)] (1) and compound (+)-(R_p,R)-[Pd{[(Et–CC–Et)₂(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl] (7a) have also been characterized by X-ray diffraction. Electrochemical studies based on cyclic voltammetries of all the compounds are also reported.     

On the reactivity of less common halopseudohalogens towards metalcarbon- and metalmetal-bonded compounds

Freshly generated solutions of iodine azide (IN₃) and iodine isocyanate (INCO) in acetonitrile or carbon tetrachloride add oxidatively to tertiaryaryl derivatives of group VB elements, Ar₃M (Ar = Ph, p-tolyl, p-ClC₆H₄ or p-FC₆H₄, and M = As, Sb or Bi) and diaryltellurium(II), Ar₂Te (Ar = Ph or p-CH₃OC₆H₄) at −10°C to −5°C to give stable covalent monomeric products, Ar₃MIX and Ar₂TeIX, respectively (where X = N₃ or NCO). The mode of bonding of the pseudohalide group to M has been established by solid-state IR spectra. Ar₃MI(N₃) failed to react with CS₂ but reaction with PhNCY (Y = O or S) gave cyclic tetrazole derivatives. Contrasting behaviour was also observed in the metathetic reaction of Ar₂MIX and Ar₂TeIX with silver pseudohalides [AgX′ (X′ = NCO or NCS)]. The tetraorgano compounds, R₄M (M = Sn or Pb, and R = Ph or p-tolyl), and Bu₃SnPh failed to react with IN₃ and Bu₃SnPhINCO but IN₃ cleaved one tin-aryl bond from Ar₄Sn in the presence of AlCl₃. Addition of IN₃ and INCO across the olefinic bond of Ph₃SnCH₂CHCH₂ is preferred to tin-allyl bond cleavage. Reactions of hexaaryldileads with IN₃ and INCO under appropriate conditions proceeded with the cleavage of a PbPb bond. Parallel reactions of cyanogen halides (CNI and CNBr) resulted in the formation of corresponding triaryllead halides and pseudohalide derivatives.