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.     

The Role of the “Ligand Periphery” in the Coordination of Tripodal Triamidostannates(II) to Iridium: Simple Ligation vs. Cyclometallation

Reaction of the triamidostannates(II) MeSi{SiMe₂N(3,5‐xyl)}₃SnLi(OEt₂) ( 2a ) and MeSi{SiMe₂N(p‐tol)}₃SnLi(OEt₂) ( 2b ) with [IrCl(CO)(PPh₃)₂] gave the Ir^I‐Sn complex [MeSi{SiMe₂N(3,5‐xyl)}₃SnIr(PPh₃)₂(CO)] ( 3a ) for the former. In contrast, for the tolyl stannate CH‐activation occurred to give the Ir^III compound [MeSi{SiMe₂N(p‐tol)}₂{SiMe₂N(2‐C₆H₃‐4‐CH₃)}SnIr(H)(PPh₃)₂(CO)] ( 3b ). The latter is thus avoided by introduction of suitably placed substituents in the peripheral aryl groups of the triamidostannate ligand.     

Synthese und Charakterisierung heterobimetallischer Bis(trimethylsilyl)phosphanide von Barium und Zinn

Synthesis and Characterization of Hetero-bimetallic Bis(trimethylsilyl)phosphanides of Barium and Tin The reaction of barium bis[bis(trimethylsilyl)amide] with one equivalent of bis(trimethylsilyl)phosphane in 1,2-dimethoxyethane (dme) yields the heteroleptic dimeric (dme)barium bis(trimethylsilyl)amide bis(trimethylsilyl)phosphanide. This colorless compound crystallizes in the monoclinic space group P2₁/n with a = 1 259.1(3), b = 1 822.7(4), c = 1 516.1(3) pm, β = 110.54(3)° and Z = 4. The central moiety of the centrosymmetric molecule is the planar Ba₂P₂-cycle with Ba? P-bond lengths of 329 and 334 pm. In the presence of bis[bis(trimethylsilyl)amino]stannylene hetero-bimetallic bis(trimethylsilyl)phosphanides of tin(II) and barium are isolated. If the reaction of Ba[N(SiMe₃)₂]₂ and Sn[N(SiMe₃)₂]₂ in the molar ratio of 1:2 with six equivalents of HP(SiMe₃)₂ is performed in toluene, barium bis{tin(II)-tris[bis(trimethylsilyl)phosphanide]} can be isolated. This compound crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 1 265.1(1), b = 2 290.1(3), c = 2 731.9(3) pm and Z = 4. The anions {Sn[P(SiMe₃)₂]₃}^? bind as two-dentate ligands to the barium atom which shows the extraordinary low coordination number of four. The addition of tetrahydrofuran (thf) to the above mentioned reaction solution leads to the elimination of tris(trimethylsilyl)phosphane and the formation of thf complexes of barium bis{tin(II)-bis(trimethylsilyl)phosphanide-trimethylsilylphosphandiide}. The derivative crystallizes from toluene in the monoclinic space group P2₁/c with a = 1 301.9(2), b = 2 316.3(3), c = 3 968.7(5) pm, β = 99.29(1)° and Z = 8.     

Synthese von substituierten Calcium-bis(disilylamiden) mittels der Transmetallierung von Zinn(II)- und Zinn(IV)-amiden

Synthesis of Substituted Calcium-bis(disilylamides) by Transmetalation of Tin(II) and Tin(IV) Amides Stannylenes as well as stannanes with substituted disilylamino groups are valuable synthons for the synthesis of alkaline earth metal bis(disilylamides) via the transmetallation reaction. Whereas bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentyl]stannylene 1 is a suitable reagent for this type of reaction, bis[trimethylsilyl-tris(trimethylsilyl)silylamino]stannylene 2 (monoclinic, P2₁/c, a = 1492.6(2), b = 1705.2(2), c = 1865.3(3) pm, β = 109.03(2)º, Z = 4) is not only attacked at the Sn? N-bond but also the N? Si-bond is cleaved by calcium metal. Similar light sensitivity as for 2 is observed for the mercury bis[trimethylsilyl-tris(trimethylsilyl)silylamide] 3 , the homolytic M? N-bond cleavage leads to the formation of the trimethylsilyl-tris(trimethylsilyl)silylamino radical (g = 2.00485; a(N) = 16.2 G). The calcium tin exchange reaction of 1 in THF yields tris(tetrahydrofuran-O)calcium-bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentanide] 4 (monoclinic, P2₁/n, a = 1060.9(2), b = 1919.3(5), c = 1686.0(3) pm, β = 90.30(2)º, Z = 4). The stannanes Me_n-4Sn[N(SiMe₃)₂]_n with n = 1 or 2 are also valuable materials for the synthesis of bis(tetrahydrofuran-O)calcium-bis[bis(trimethylsilyl)amide].     

Transmetallierung von Zinn(II) in [Sn(μ3‐PSitBu3)]4 durch Barium – von Sn4P4‐Heterocuban‐Strukturen zu heterobinuklearen Käfigverbindungen mit einem zentralen BanSn4−nP4‐Heterocuban‐Polyeder (n = 1, 2 und 3)

Transmetallation of Tin(II) in [Sn(μ₃‐PSitBu₃)]₄ by Barium – from Sn₄P₄ Heterocubane Structures to Heterobinuclear Cage Compounds with a Central Ba_nSn_4?nP₄ Heterocubane Polyhedron (n = 1, 2 and 3) For the preparation of compounds of the type [Ba_nSn_4?n(PSitBu₃)₄] (n = 1 ( 2 ), 2 ( 3 ) and 3 ( 4 )) two synthetic routes are applicable: in the transmetallation reaction homometallic [Sn₄(PSitBu₃)₄] ( 1 ) reacts with barium metal and in a deprotonation reaction (metallation) tri(tert‐butyl)silylphosphane reacts simultaneously with (thf)₂Ba[N(SiMe₃)₂]₂ and Sn[N(SiMe₃)₂]₂. During the transmetallation reaction mixtures of the heterobimetallic cage compounds 2 to 4 are obtained, however, analytically pure compounds 2 and 3 are accessible by the metallation reaction. Compound 4 is formed as a minor product together with 3 . Due to the larger Ba‐P bond lengths compared to the Sn‐P values the substitution of tin by barium leads to strong distortions of the heterocubane moiety. With NMR‐spectroscopic experiments one could show that all the above mentioned compounds form Ba_nSn_4?nP₄ heterocubane cage structures.     

Lateral Metallation and Redistribution Reactions of Sodium Ferrates Containing Bulky 2,6-Diisopropyl-N-(trimethylsilyl)anilide Ligands

Alkali-metal ferrates containing amide groups have emerged as regioselective bases capable of promoting Fe−H exchanges of aromatic substrates. Advancing this area of heterobimetallic chemistry, a new series of sodium ferrates is introduced incorporating the bulky arylsilyl amido ligand N(SiMe₃)(Dipp) (Dipp=2,6-iPr₂-C₆H₃). Influenced by the large steric demands imposed by this amide, transamination of [NaFe(HMDS)₃] (HMDS=N(SiMe₃)₂) with an excess of HN(SiMe₃)(Dipp) led to the isolation of heteroleptic [Na(HMDS)₂Fe{N(SiMe₃)Dipp}]_∞ ( 1 ) resulting from the exchange of just one HMDS group. An alternative co-complexation approach, combining the homometallic metal amides [NaN(SiMe₃)Dipp] and [Fe{N(SiMe₃)Dipp}₂] induces lateral metallation of one Me arm from the SiMe₃ group in the iron amide furnishing tetrameric [NaFe{N(SiCH₂Me₂)Dipp}{N(SiMe₃)Dipp}]₄ ( 2 ). Reactivity studies support that this deprotonation is driven by the steric incompatibility of the single metal amides rather than the basic capability of the sodium reagent. Displaying synergistic reactivity, heteroleptic sodium ferrate 1 can selectively promote ferration of pentafluorobenzene using one of its HMDS arms to give heterotrileptic [Na{N(SiMe₃)Dipp}(HMDS)Fe(C₆F₅)]_∞ ( 4 ). Attempts to deprotonate less activated pyridine led to the isolation of NaHMDS and heteroleptic Fe(II) amide [(py)Fe{N(SiMe₃)Dipp}(HMDS)] ( 5 ), resulting from an alternative redistribution process which is favoured by the Lewis donor ability of this substrate.     

Synthesis and Structural Characterization of Bis(tetrahydro­pyran)calcium Bis[bis(trimethylsilyl)amide]

Transmetalation of Sn[N(SiMe₃)₂]₂ with calcium granules in tetrahydropyran (thp) yields colorless [(thp)₂Ca{N(SiMe₃)₂}₂] ( 1 ) which is soluble in common organic solvents. The calcium center is in a distorted tetrahedral environment with Ca–N and Ca–O bond lengths of 231.08(11) and 240.23(9) pm, respectively. The molecular structure is dominated by steric factors leading to a NCaN bond angle of 119.43(6)°.     

Synthesis and Molecular Structure of a Hexaaminodistannane Comprising two Identical Triaminotin Subunits

Reaction of the previously characterized lithium stannate [HC{SiMe₂N(4‐CH₃C₆H₄)}₃SnLi(thf)₃] ( 1 ) with AgCl afforded the corresponding distannane [HC{SiMe₂N(4‐CH₃C₆H₄)}₃Sn]₂ ( 2 ) as the product of an oxidative coupling in good yield. Its [2, 2, 2]bicyclooctane‐related cage structure, comprising the trisilylmethane unit and the triamido‐tin fragment, as well as the Sn‐Sn bond (2.8204(4)Å) were established by single crystal structure analysis: Space group group P2₁/n, Z = 2, lattice dimensions at 120(2) K: a = 13.6515(3), b = 15.8391(3), c = 16.3522(3)Å, β = 102.7760(10)°, R₁ = 0.0347.     

Synthesis and Characterisation of N,N′-Disubstituted 1,2-phenylenebis(amido)tin(II) Compounds; X-Ray structures of 1,2- and of [1,2- (tmeda)

Cyclic bis(amido)tin(II) compounds 1,2- [R = SiMe₃] ( 4 ), SiMe₂Bu^t ( 5 ) and CH₂Bu^t ( 6 )], as well as ( 4 )₂(μ-tmeda) 7 have been obtained either from (i) the corresponding dilithium compound 1,2-C₆H₄[N(R)Li]₂ 1–3 and SnCl₂ for 4–6 , respectively, (or for 4 ) 2 1 + [Sn(μ-Cl){N(SiMe₃)₂}]₂; or (ii) 1,2-C₆H₄[N(H)R]₂ + Sn[N(SiMe₃)₂]₂ for 4–6 ; or for 7 from 4 and tmeda. Compounds 4–6 are monomeric, yellow, thermochromic (becoming redder on heating), diamagnetic, crystalline and are lipophilic and sublimable in vacuo. Compound 7 is colourless. The molecular structures of 6 and 7 have been determined from single crystal X-ray diffraction data. Compound 6 crystallises in bimolecular aggregates, in which there is a weak η-C₆ … Sn contact.     

Oxidative Addition of Diethylchalcogenanes to Lappert's Germylene and Stannylene

Oxidative addition of diethyldichalcogenanes Et₂E₂ (E = S, Se, Te) to bis[bis(trimethylsilyl]amido]germylene and ‐stannylene M[N(SiMe₃)₂]₂ (M = Ge, Sn) proceed with formation of the corresponding bis(ethylchalcogenato)germanes (Me₃Si)₂N)₂Ge(EEt)₂ [E = S ( 1 ), Se ( 2 ), Te ( 3 )] and ‐stannanes (Me₃Si)₂N)₂Sn(EEt)₂ [E = S ( 4 ), Se ( 5 ), Te ( 6 )]. The solid state structures of 1 – 6 were determined by single‐crystal X‐ray diffraction.     

Kristallstruktur des Zinkamids Zn[N(SiMe3)2]2

Crystal Structure of the Zinc Amide Zn[N(SiMe₃)₂]₂ X‐ray quality crystals of Zn[N(SiMe₃)₂]₂ (monoclinic, P2₁/c) are obtained by sublimation of the zinc amide Zn[N(SiMe₃)₂]₂ at —30 °C in vacuo (300 torr). According to the result of the X‐ray structural analysis, Zn[N(SiMe₃)₂]₂ contains an almost linear N‐Zn‐N unit with two short N‐Zn bonds.     

Aminostannanes and aminostannylenes containing a C,N-chelated ligand

Aminotin(II and IV) compounds {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂, {2-[(CH₃)₂NCH₂]C₆H₄}₂Sn[N(H)(2,6-i-Pr-C₆H₃)]₂ and {2-[(CH₃)₂NCH₂]C₆H₄}Sn[N(2,6-i-Pr-C₆H₃)(SiMe₃)] were prepared by lithium halide elimination from tin halides and corresponding lithium complexes. [(2,6-i-Pr-C₆H₃)(H)N]Li (1) reacts with one half of molar equivalent of SnCl₂ to give {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂. The same lithium amide (1) gave with R₃SnCl corresponding aminostannanes. Further reactions of these compounds with n-butyllithium gave the starting 1 and tetraorganostannanes. {2-[(CH₃)₂NCH₂]C₆H₄}₂SnBr₂ reacts with two equivalents of 1 to {2-[(CH₃)₂NCH₂]C₆H₄}₂Sn[N(H)(2,6-i-Pr-C₆H₃)]₂. The dimeric heteroleptic stannylene {[(2,6-i-Pr-C₆H₃)(SiMe₃)N](μ₂-Cl)Sn}₂ reacts with 2-[(CH₃)₂NCH₂]C₆H₄Li to the monomeric {2-[(CH₃)₂NCH₂]C₆H₄}Sn[N(2,6-i-Pr-C₆H₃)(SiMe₃)]. The structure in the solid state and in solution and reactivity of products is also discussed. The unique decatin cluster has been isolated by hydrolysis of {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂. The structure of some compounds was also evaluated by theoretical DFT methods.     

A Heteroleptic (E)-1,2-Diaryl-1,2-disilyldistannene without Donor Stabilization

The reaction of the stannylene R₂Sn : (R = 2-tBu-4,5,6-Me₃C₆H) with R′₂Sn (R′ = Si(SiMe₃)₃) proceeds with substituent exchange to afford the heteroleptic stannylene RR′Sn : which, in the solid state, forms the distannene RR′Sn = SnRR′ ( 7 ). The X-ray structure analysis of 7 reveals a trans-bent arrangement of the substituents with a large fold angle of 44.9° and an Sn–Sn double bond length of 279.14(4) pm.     

Two‐Coordinate Iron(I) Complex [Fe{N(SiMe3)2}2]−: Synthesis,Properties, and Redox Activity

First‐row two‐coordinate complexes are attracting much interest. Herein, we report the high‐yield isolation of the linear two‐coordinate iron(I) complex salt [K(L)][Fe{N(SiMe₃)₂}₂] (L=18‐crown‐6 or crypt‐222) through the reduction of either [Fe{N(SiMe₃)₂}₂] or its three‐coordinate phosphine adduct [Fe{N(SiMe₃)₂}₂(PCy₃)]. Detailed characterization is gained through X‐ray diffraction, variable‐temperature NMR spectroscopy, and magnetic susceptibility studies. One‐ and two‐electron oxidation through reaction with I₂ is further found to afford the corresponding iodo iron(II) and diiodo iron(III) complexes.     

Synthesis and Thermal Decomposition of Heavy Tetrylenes Bearing N-Aminocarbazolyl Substituents

The synthesis of the N-aminocarbazole R-NH₂ ( 2 ) is reported. Subsequent reaction with bis[bis(trimethylsilyl)amido]tetrylenes E[N(SiMe₃)₂]₂ (E=Ge, Sn, or Pb) allowed the isolation of formal hydrazidotetrylene derivatives, R−N(H)EN(SiMe₃)₂ ( 3 ) that includes the first example of a hydrazidoplumbylene to date. Thermal decomposition of these compounds resulted in the elimination of “NH” and afforded the tetrylenes R-EN(SiMe₃)₂ ( 4 ).     

Two‐Coordinate Iron(I) Complex [Fe{N(SiMe3)2}2]−: Synthesis,Properties, and Redox Activity

First‐row two‐coordinate complexes are attracting much interest. Herein, we report the high‐yield isolation of the linear two‐coordinate iron(I) complex salt [K(L)][Fe{N(SiMe₃)₂}₂] (L=18‐crown‐6 or crypt‐222) through the reduction of either [Fe{N(SiMe₃)₂}₂] or its three‐coordinate phosphine adduct [Fe{N(SiMe₃)₂}₂(PCy₃)]. Detailed characterization is gained through X‐ray diffraction, variable‐temperature NMR spectroscopy, and magnetic susceptibility studies. One‐ and two‐electron oxidation through reaction with I₂ is further found to afford the corresponding iodo iron(II) and diiodo iron(III) complexes.     

Chemistry of Stannylene‐Based Lewis Pairs: Dynamic Tin Coordination Switching Between Donor and Acceptor Character

The coordination chemistry of cyclic stannylene‐based intramolecular Lewis pairs is presented. The P→Sn adducts were treated with [Ni(COD)₂] and [Pd(PCy₃)₂] (COD=1,5‐cyclooctadiene, PCy₃=tricyclohexylphosphine). In the isolated coordination compounds the stannylene moiety acts either as an acceptor or a donor ligand. Examples of a dynamic switch between these two coordination modes of the P?Sn ligand are illustrated and the structures in the solid state together with heteronuclear NMR spectroscopic findings are discussed. In the case of a Ni⁰ complex, ¹¹⁹Sn Mössbauer spectroscopy of the uncoordinated and coordinated phosphastannirane ligand is presented.     

Synthesis and Molecular Structure of a C3‐chiral Triaminodistannane

Reaction of the chiral lithium stannate [HC{SiMe₂N[(S)–CH(Me)Ph]}₃SnLi(thf)] ( 1 ) with Me₃SnCl gave the corresponding distannane [HC{SiMe₂N[(S)–CH(Me)Ph]}₃Sn–SnMe₃] ( 2 ) in good yield. Its [2,2,2]bicyclooctane‐related cage structure, comprising the trisilylsilane unit and the triamido‐tin fragment, as well as the Sn–Sn bond (2.7978(15)–2.8020(15) Å in the three crystallographically independent molecules) were established by a single crystal X‐ray structure analysis: Space proup P3, Z = 3, lattice dimensions at 293(2) K: a = 17.724(3), c = 10.597(2) Å, R = 0.0374.     

Methylmetall-bis(trimethylsilyl)amidoderivate des Aluminiums,Galliums und Arsens

Methyl Metal Bis(trimethylsilyl)amido Derivatives of Aluminium, Gallium, and Arsenic MeAl[N(SiMe₃)₂]₂ (Me ? CH₃) has been prepared by the reaction of AlMe₃ with HN(SiMe₃)₂ in a 1:2 molar ratio. The homologue Gallium compound (as well as the Aluminium derivative) is formed in good yields by the interaction of MeMcl₂ (M = Al, Ga) with Li- and Na[N(SiMe₃)₂], respectively. MeAs[N(SiMe₃)₂]₂ is formed by the reaction of AsCl₃ and Na[N(SiMe₃)₂] in a 1:3 molar ratio. These colourless amido derivatives are monomeric in solution, they have been characterized by analyses, mass, n.m.r. (¹H and ¹³C), and especially by i.r. and Raman spectra.     

Perfluorinated tert‐Butoxides of Tin(II): The Dimeric Alkoxide and Its Monomeric Ate Complex

Surprisingly little is known about fluorinated tin(II) alkoxides. Here the synthesis and characterization of Sn(OR^F)₂ [OR^F = OC(CF₃)₃] and the crystal structures of its adducts with phenanthroline and dppe are reported. In addition, its ate complex [Sn(OR^F)₃]^– was synthesized with lithium or sodium as cation and as acetonitrile adduct. The thermolytic behavior of both, the alkoxide and the lithium stannate(II), was investigated together with first electrochemical measurements of Li[Sn(OR^F)₃].