Alkali Metal Di‐tert‐butylphenylsilanides — tBu2PhSiM (M = Li,Na, K) — Syntheses,Structures, and Reactivity

The alkali metal silanides tBu₂PhSiM (M = Li, Na, K) are quantitatively accessible from the reaction of tBu₂PhSiBr with alkali metals in heptane, tetrahydrofuran, and benzene at moderately elevated temperature. In contrast to the polymer structure of unsolvated tBu₂PhSiNa, the solvated di‐tert‐butylphenylsilanides tBu₂PhSiNa(THF), tBu₂PhSiK(C₆H₆), tBu₂PhSiK(THF), and tBu₂PhSiK(THF)₂ possess a novel feature in their crystal structures with a dimeric arrangement of tBu₂PhSiM units via π interaction between the tBu₂PhSi group and the alkali metal centers. The alkali metal siloxides tBu₂PhSiOM (M = Li, Na, K) can be synthesized almost quantitatively from tBu₂PhSiM (M = Li, Na, K) with N₂O in tetrahydrofuran at —78 °C. Single crystals of the silanol tBu₂PhSiOH have been obtained from the protolysis of tBu₂PhSiONa with (NH₄)₂SO₄.     

Reactions of tBu2P–PLi–PtBu2 with [(Et3P)2MCl2] (M = Ni,Pd, Pt). Synthesis and Properties of [(1,2‐η‐tBu2P=P–PtBu2)M(PEt3)Cl] (M=Ni,Pd)

^tBu₂P–PLi–P^tBu₂·2THF reacts with [cis‐(Et₃P)₂MCl₂] (M = Ni, Pd) yielding [(1,2‐η‐^tBu₂P=P–P^tBu₂)Ni(PEt₃)Cl] and [(1,2‐η‐^tBu₂P=P–P^tBu2)Pd(PEt₃)Cl], respectively. ^tBu₂P– PLi–P^tBu₂ undergoes an oxidation process and the ^tBu₂P–P–P^tBu₂ ligand adopts in the products the structure of a side‐on bonded 1,1‐di‐tert‐butyl‐2‐(di‐tert‐butylphosphino)diphosphenium cation with a short P–P bond. Surprisingly, the reaction of ^tBu₂P–PLi–P^tBu₂·2THF with [cis‐(Et₃P)₂PtCl₂] does not yield [(1,2‐η‐^tBu₂P=P–P^tBu₂)Pt(PEt₃)Cl].     

Synthese,spektroskopische Charakterisierung und Molekülstrukturen ausgewählter Lewis‐Basen‐Addukte der Alkalimetall‐tri(tert‐butyl)silylphosphanide

Synthesis, Spectroscopic Characterization, and Molecular Structures of Selected Lewis‐Base Adducts of the Alkali Metal Tri(tert‐butyl)silylphosphanides The metalation of tri(tert‐butyl)silylphosphane with butyllithium and the bis(trimethylsilyl)amides of sodium, potassium, and rubidium yields quantitatively the corresponding alkali metal tri(tert‐butyl)silylphosphanides, which crystallize after addition of appropriate Lewis‐bases as dimeric (DME)LiP(H)SitBu₃ ( 1 ), chain‐like (DME)NaP(H)SitBu₃ ( 2 ), monomeric ([18]Krone‐6)KP(H)SitBu₃ ( 3 ), and dimeric (TMEDA)_1.5RbP(H)SitBu₃ ( 4 ). The reaction of H₂PSitBu₃ with cesium bis(trimethylsilyl)amide at room temperature gives monocyclic and tetrameric cesium tri(tert‐butyl)silylphosphanide ( 5 ) with two additional coordinated CsN(SiMe₃)₂ molecules. At 80 °C this complex reacts with excess of phosphane to the tetrameric toluene adduct (η⁶‐Toluol)CsP(H)SitBu₃ ( 6 ) which contains a central Cs₄P₄‐heterocubane fragment. The constitution of these compounds was verified by X‐ray structure determinations.     

Alkali‐Metal Pyrazolate Complexes with Unusual Pyrazolate Coordination Modes and Pseudocubane Motifs

The dimeric complex [Li(Ph₂pz)(OEt₂)]₂ ( 1 ) and tetrameric cluster [Na(Ph₂pz)(thf)]₄ ( 2 ) were prepared by treatment of alkali‐metal reagents (nBuLi and Na{N(SiMe₃)₂}, respectively) with 3,5‐diphenylpyrazole (Ph₂pzH) in Et₂O ( 1 ) or THF ( 2 ). The polymer [Na(tBu₂pz)]_n ( 3 ) was obtained from reaction at elevated temperature in a sealed tube between Na metal and 3,5‐di‐tert‐butylpyrazole (tBu₂pzH). The complex [Na₄(tBu₂pz)₂(thf)₃(obds)]₂ ( 4 ; obds=(OSiMe₂)₂O) was obtained as a minor product from prolonged treatment of tBu₂pzH with elemental sodium in a silicone‐greased flask. All four alkali‐metal pyrazolato complexes were characterized by IR and ¹H NMR spectroscopy and X‐ray crystallography.The Li dimer 1 displays μ‐η²:η¹ lithium–pyrazolato binding, in which both lithium atoms are four‐coordinate. Room‐ and variable‐temperature NMR studies (¹H, ¹³C, and ⁷Li) of 1 suggest similar behavior in solution, with peaks coalescing at low temperatures. Complexes 2 and 4 display distorted cubane structures. In 2 , all the sodium atoms are five‐coordinate, whereas 4 contains two sodium/pyrazolate/thf clusters (4:2:3 ratio) bridged by two obds^2? units, as well as two four‐coordinate and two five‐coordinate sodium atoms. Compound 3 is composed of two independent chains with the unusual coordination modes μ₃‐η⁵:η²:η², μ₃‐η⁵:η²:η¹, and μ₃‐η⁴:η²:η¹, with five‐, six‐, and seven‐coordinate sodium atoms. Two oxo‐centered M₈ cage complexes [(tBu₂pz)₆Li₈O] ( 5 ) and [(tBu₂pz)₆Na₈O] ( 6 ) were obtained as by‐products from attempted preparation of [Li(tBu₂pz)] and [Na(tBu₂pz)], respectively, and their structures were determined.     

The Synthesis of tert‐Butyl(dichloromethyl)bis(trimethylsilyl)silane and (Dibromomethyl)ditert‐butyl(trimethylsilyl)silane and their Reactions with Organolithium Derivatives

tert‐Butyl(dichloromethyl)bis(trimethylsilyl)silane ( 4 ), prepared by the reaction of tert‐butylbis(trimethylsilyl)silane with trichloromethane and potassium tert‐butoxide, reacted with 2,4,6‐triisopropylphenyllithium (TipLi) (molar ratio 1 : 2) at room temperature to give (after hydrolytic workup) the silanol tBu(2,4,6‐iPr₃C₆H₂)Si(OH)–CH(SiMe₃)₂ ( 15 ). The formation of 15 is discussed as proceeding through the indefinitely stable silene tBu(2,4,6‐iPr₃C₆H₂)Si=C(SiMe₃)₂ ( 13 ), but attempts to isolate the compound failed. Treatment of (dibromomethyl)ditert‐butyl(trimethylsilyl)silane ( 7 ), made from tBu₂(Me₃Si)SiH, HCBr₃ and KOtBu, with methyllithium (1 : 3) at –78 °C afforded tBu₂MeSi–CHMeSiMe₃ ( 19 ); 7 and phenyllithium (1 : 3) under similar conditions gave tBu₂PhSi–CH₂SiMe₃ ( 20 ). The reaction paths leading to 15 , 19 and 20 are discussed. Reduction of 7 with lithium in THF produced the substituted ethylene tBu₂(Me₃Si)SiCH=CHSitBu₂SiMe₃ ( 21 ). For 21 the results of an X‐ray structural analysis are given.     

Synthesis and solid‐state structures of t‐Bu3Ga–EPh3 Lewis acid–base adducts

Three Lewis acid–base adducts t‐Bu₃Ga–EPh₃ (E = P 1 , As 2 , Sb 3 ) were synthesized by reactions of Ph₃E and t‐Bu₃Ga and characterized by heteronuclear NMR (¹H, ¹³C (³¹P)) and IR spectroscopy, elemental analysis and single crystal X‐ray diffraction. Their structural parameters are discussed and compared to similar t‐Bu₃Ga adducts. The strength of the donor‐acceptor interactions within 1 – 3 was investigated in solution by temperature‐dependent ¹H NMR spectroscopy and by quantum chemical calculations.     

Cationic organotin cluster [t‐Bu2Sn(OH)(H2O)]22+2OTf−‐catalyzed one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in water

The cationic organotin cluster [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? is easy to prepare and stable in air. The catalytic activity of [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? as a neutral organotin Lewis acid catalyst is probed through the one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles from aldehydes, hydroxylamine hydrochloride and sodium azide, and of 2,4,6‐triarylpyridines from aromatic aldehydes, substituted acetophenones and ammonium acetate. The reactions proceed well in the presence of 1 mol% of [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? in water and provide the corresponding 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in good to excellent yields. The method reported has several advantages such as the catalyst being neutral, low catalyst loading and use of water as a green solvent.     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXV. Bildung und Struktur des [{cyclo‐P3(PtBu2)3}{Ni(CO)2}{Ni(CO)3}]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXV. Formation and Structure of [{ cyclo ‐P₃(P^tBu₂)₃}{Ni(CO)₂}{Ni(CO)₃}] ^tBu₂P–P=P(R)^tBu₂ (R = Br, Me) reacts with [Ni(CO)₄] yielding [{cyclo‐P₃(P^tBu₂)₃}{Ni(CO)₂}{Ni(CO)₃}]. The two cis‐^tBu₂P substituents of the cyclotriphosphane, which results from the trimerization of the phosphinophosphinidene ^tBu₂P–P, are coordinating to a Ni(CO)₂ unit forming a five‐membered P₄Ni chelate ring. The trans‐^tBu₂P group is linked to a Ni(CO)₃ unit. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with a = 933.30(5), b = 2353.2(1) and c = 3474.7(3) pm.     

Zum Einfluß der PR3‐Liganden auf Bildung und Eigenschaften der Phosphinophosphiniden‐Komplexe [{η2‐tBu2P–P}Pt(PR3)2] und [{η2‐tBu2P1–P2}Pt(P3R3)(P4R′3)]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes XXI The Influence of the PR₃ Ligands on Formation and Properties of the Phosphinophosphinidene Complexes [{η²‐^tBu₂P–P}Pt(PR₃)₂] and [{η²‐^tBu₂P¹–P²}Pt(P³R₃)(P⁴R′₃)] (R₃P)₂PtCl₂ and C₂H₄ yield the compounds [{η²‐C₂H₄}Pt(PR₃)₂] (PR₃ = PMe₃, PEt₃, PPhEt₂, PPh₂Et, PPh₂Me, PPh₂ⁱPr, PPh₂^tBu and P(p‐Tol)₃); which react with ^tBu₂P–P=PMe^tBu₂ to give the phosphinophosphinidene complexes [{η²‐^tBu₂P–P}Pt(PMe₃)₂], [{η²‐^tBu₂P–P}Pt(PEt₃)₂], [{η²‐^tBu₂P–P}Pt(PPhEt₂)₂], [{η²‐^tBu₂P–P}Pt(PPh₂Et)₂], [{η²‐^tBu₂P–P}Pt(PPh₂Me)₂], [{η²‐^tBu₂P–P}Pt(PPh₂ⁱPr], [{η²‐^tBu₂P–P}Pt(PPh₂^tBu)₂] and [{η²‐^tBu₂P–P}Pt(P(p‐Tol)₃)₂]. [{η²‐^tBu₂P–P}Pt(PPh₃)₂] reacts with PMe₃ and PEt₃ as well as with ^tBu₂PMe, PⁱPr₃ and P(c‐Hex)₃ by substituting one PPh₃ ligand to give [{η²‐^tBu₂P¹–P²}Pt(P³Me₃)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Ph₃)(P⁴Me₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Et₃)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Me^tBu₂)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³ⁱPr₃)(P⁴Ph₃)] and [{η²‐^tBu₂P¹–P²}Pt(P³(c‐Hex)₃)(P⁴Ph₃)]. With ^tBu₂PMe, [{η²‐^tBu₂P–P}Pt(P(p‐Tol)₃)₂] forms [{η²‐^tBu₂P¹–P²}Pt(P³Me^tBu₂)(P⁴(p‐Tol)₃)]. The NMR data of the compounds are given and discussed with respect to the influence of the PR₃ ligands.     

The Reactions of Carbon Monoxide with Silyl and Silenyl Lithium – Synthesis and Isolation of the First Stable Tetra‐Silyl Di‐Ketyl Biradical and 1‐Silaallenolate Lithium

Reactions of carbon monoxide (CO) with tBu₂MeSiLi and (E)‐(tBu₂MeSi)(tBuMe₂Si)C=Si(SiMetBu₂)Li?2 THF ( 4 ) were studied both experimentally and computationally. Reaction of tBu₂MeSiLi with CO in hexane yields the first stable tetra‐silyl di‐ketyl biradical [(tBu₂MeSi)₂COLi]^.₂ ( 3 ). Reaction of 4 with CO yields selectively and quantitatively the first reported 1‐silaallenolate, (tBu₂MeSi)(tBuMe₂Si)C=C=Si(SiMetBu₂)OLi?THF ( 5 ). Both 3 and 5 were characterized by X‐ray crystallography and biradical 3 also by EPR spectroscopy. Silaallenolate 5 reacts with Me₃SiCl to produce siloxy substituted 1‐silaallene (tBu₂MeSi)(tBuMe₂Si)C=C=Si(SiMetBu₂)OSiMe₃. The reaction of 4 with CO provides a new route to 1‐silaallenes. The mechanisms of the reactions of tBuMe₂SiLi and of 4 with CO were studied by DFT calculations.     

(Di‐tert‐butylmethylphosphane)(η2‐di‐tert‐butylphosphanylphosphinidene)(triphenylphosphane)platinum(0)

The crystal structure of the title compound, [Pt(C₈H₁₈P₂)(C₉H₂₁P)(C₁₈H₁₅P)] or [(Ph₃P)(^tBu₂PMe)Pt(η²‐^tBu₂PP)], contains four molecules in the asymmetric unit with slightly different conformations. The P—P distances in the ^tBu₂PP ligands are similar for all four molecules [2.0661 (13)–2.0678 (13) Å] and indicate a multiple character of the P—P bond in the ^tBu₂PP ligand. Molecules of the asymmetric unit can be assembled into a tetrahedron that fulfils the requirements for a rhombic disphenoid. The coordination of the Pt atom in all four molecules is square planar, with r.m.s. deviations from the PtP₄ planes in the range 0.03–0.05 Å. All planes of the PtP₄ groups are approximately parallel to the ab plane of the unit cell. The structure represents an unusual unsymmetrical platinum phosphinidene derivative.     

[Co(g5‐Me5C5)(g3‐tBu2PPCH–CH3)] aus [Co(g5‐Me5C5)(g2‐C2H4)2] und tBu2P–P=P(Me)tBu2

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XVII [1] [Co(g⁵‐Me₅C₅)(g³‐^tBu₂PPCH–CH₃)] from [Co(g⁵‐Me₅C₅)(g²‐C₂H₄)₂] and ^tBu₂P–P=P(Me)^tBu₂ [Co(η⁵‐Me₅C₅)(η³‐^tBu₂PPCH–CH₃)] 1 is formed in the reaction of [Co(η⁵‐Me₅C₅)(η²‐C₂H₄)₂] 2 with ^tBu₂P–P 4 (generated from ^tBu₂P–P=P(Me)^tBu₂ 3 ) by elimination of one C₂H₄ ligand and coupling of the phosphinophosphinidene with the second one. The structure of 1 is proven by ³¹P, ¹³C, ¹H NMR spectra and the X‐ray structure analysis. Within the ligand ^tBu₂P¹P²C¹H–CH₃ in 1 , the angle P1–P2–C1 amounts to 90°. The Co, P1, P2, C1 atoms in 1 look like a „butterfly”︁. The reaction of 2 with a mixture of ^tBu₂P–P=P(Me)^tBu₂ 3 and ^tBu–C?P 5 yields [Co(η⁵‐Me₅C₅){η⁴‐(^tBuCP)₂}] 6 and 1 . While 6 is spontaneously formed, 1 appears only after complete consumption of 5 .     

Disilene R*RSi=SiRR* (R* = SitBu3) mit siliciumgebundenen Me‐ und Ph‐Gruppen R: Bildung,Nachweis, Thermolyse,Struktur: Verbindungen des Siliciums. 154 [1]. Ungesättigte Siliciumverbindungen. 61 [1]

Compounds of Silicon. 154 [1]. Unsaturated Silicon Compounds. 61 [1] Disilenes R*RSi=SiRR* (R* = SitBu₃) with Silicon‐Bound Me and Ph Groups R: Formation, Identification, Thermolysis, Structure Dehalogenations of the 1, 2‐disupersilylsilanes R*MeBrSi—SiBrMeR* (gauche : trans 1.15 : 1.00) and R*PhClSi—SiBrPhR* (gauche : trans = 2.7 : 1.0) in THF with equimolar amounts of NaR* (R* = SitBu₃ = Supersilyl) lead at —78 °C under exchange of bromine for sodium to the disilanides R*MeBrSi—SiNaMeR* and R*PhClSi—SiNaPhR* which are identified by protonation and bromination (formation of R*RXSi—SiX′RR* with R = Me, X/X′ = Br/H, Br/Br: gauche : trans = 1.15 : 1.00, and R = Ph, X/X′ = Cl/H, Cl/Br: gauche : trans = 2.7 : 10, respectively). These eliminate at about —55 °C NaHal with formation of non‐isolable trans‐R*MeSi=SiMeR* and isolable trans‐R*PhSi=SiPhR*. The intermediate existence of the disilene R*MeSi=SiMeR* could be proved by trapping it with PhC≡CPh (formation of a [2+2] cycloadduct; X‐ray structure analysis). In the absence of trapping agents, R*MeSi=SiMeR* decomposes into a mixture of substances, the main product of which is R*MeHSi—SiMeR*—SiHMeR*. The light yellow disilene R*PhSi=SiPhR* has been characterized by spectroscopy (Raman: ν(Si=Si) = 592 cm^—1; UV/VIS: λ_max = 398 nm with ∈ = 1560; ²⁹Si‐NMR: δ(>Si=) = 128 ppm) and by X‐ray structure analysis (planar central framework >Si=Si<; Si=Si distance 2.182Å). R*PhSi=SiPhR* is reduced by lithium in THF with formation of a red radical anion which decomposes at room temperature into hitherto non‐identified products. At about 70 °C, R*PhSi=SiPhR* decomposes with intramolecular insertion of the Si=Si group into a C—H bond of a Ph group and with change of configuration of the R* groups, which at first are trans then cis‐positioned (X‐ray structure analysis of the thermolysis product).     

Bildung und Struktur von [μ‐(1,2 : 2‐η‐tBu2P–P){Mo(CO)2cp′}2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXIV. Formation and Structure of [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂] [cp′Mo(CO)₂]₂ (cp′ = C₅H₄^tBu) reacts with ^tBu₂P–P=P(Me)^tBu₂ to yield the compound [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂], which crystallizes in the space group P2₁2₁2₁ with a = 1202.42(7), b = 1552.48(8), and c = 1765.3(1) pm.     

Reaktionen von tBu2P–P=P(Me)tBu2 mit (Et3P)2NiCl2 und [{η2‐C2H4}Ni(PEt3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXIII. Reactions of ^tBu₂P–P=P(Me)^tBu₂ with (Et₃P)₂NiCl₂ and [{η²‐C₂H₄}Ni(PEt₃)₂] ^tBu₂P–P=P(Me)^tBu₂ ( 1 ) forms with (Et₃P)₂NiCl₂ ( 2 ) and Na(Nph) the [μ‐(1,3 : 2,3‐η‐^tBu₂P₄^tBu₂){Ni(PEt₃)Cl}₂] ( 3 ) as main product. Using Na/Hg instead as reducing agent the Ni⁰ compounds [{η²‐^tBu₂P–P}Ni(PEt₃)₂] ( 4 ), [{η²‐^tBu₂P–P=P–P^tBu₂}Ni(PEt₃)₂] ( 5 ) and [(Et₃P)Ni(μ‐P^tBu₂)]₂ ( 6 ) with four‐membered Ni₂P₂ ring result. [{η²‐C₂H₄}Ni(PEt₃)₂] yields with 1 also 4 . The compounds were characterized by ¹H and ³¹P{¹H} NMR investigations and 3 also by a single crystal X‐ray analysis. It crystallizes triclinic in the space group P 1 with a = 1129.4(2), b = 1256.8(3), c = 1569.5(3) pm, α = 72.44(3)°, β = 70.52(3)° and γ = 74.20(3)°.     

Heterodinukleare Komplexe: Synthese und Kristallstrukturen von [RuRh(μ‐CO)(CO)4(μ‐PtBu2)(tBu2PH)], [RuRh(μ‐CO)(CO)3(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] und [CoRh(CO)4(μ‐H)(μ‐PtBu2)(tBu2PH)]

Heterobinuclear Complexes: Synthesis and X‐ray Crystal Structures of [RuRh(μ‐CO)(CO)₄(μ‐P^tBu₂)(^tBu₂PH)], [RuRh(μ‐CO)(CO)₃(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)], and [CoRh(CO)₄(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] [Ru₃Rh(CO)₇(μ₃‐H)(μ‐P^tBu₂)₂(^tBu₂PH)(μ‐Cl)₂] ( 2 ) yields by cluster degradation under CO pressure as main product the heterobinuclear complex [RuRh(μ‐CO)(CO)₄(μ‐P^tBu₂)(^tBu₂PH)] ( 4 ). The compound crystallizes in the orthorhombic space group Pcab with a = 15.6802(15), b = 28.953(3), c = 11.8419(19) Å and V = 5376.2(11) ų. The reaction of 4 with dppm (Ph₂PCH₂PPh₂) in THF at room temperature affords in good yields [RuRh(μ‐CO)(CO)₃(μ‐P^tBu₂)(μ‐dppm)] ( 7 ). 7 crystallizes in the triclinic space group P 1 with a = 9.7503(19), b = 13.399(3), c = 15.823(3) Å and V = 1854.6 ų. Moreover single crystals of [CoRh(CO)₄(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] ( 9 ) could be obtained and the single‐crystal X‐ray structure analysis revealed that 9 crystallizes in the monoclinic space group P2₁/a with a = 11.611(2), b = 13.333(2), c = 18.186(3) Å and V = 2693.0(8) ų.     

N‐Heterocyclic Carbenes and Imidazole‐2‐thiones as Ligands for the Gold(I)‐Catalysed Hydroamination of Phenylacetylene

Gold(I) complexes of 1‐[1‐(2,6‐dimethylphenylimino)alkyl]‐3‐(mesityl)imidazol‐2‐ylidene (C^Imine_R), 1,3‐dimesitylimidazol‐2‐ylidene (IMes) and of the corresponding thione derivatives (S^Imine_R and IMesS) were prepared and structurally characterised. The solid‐state structure of the C^Imine_R and S^Imine_R gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^Imine_tBu with [AuCl(SMe₂)] led to the formation of [(C^Imine_tBu)AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^Imine_tBu)₂Au]⁺, with AuCl₂^? as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^Imine_tBu)AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline.     

Unexpected Silaazetidine Formation in the Thermolysis of thf‐Supported Silanimine Et2Si=N–SitBu3·thf

The silyl amide Et₂SiCl‐NLi‐SitBu₃ can be cleanly prepared from precursor silylamine Et₂SiCl‐NH‐SitBu₃ and Li[nBu]. The CF₃SO₃SiMe₃ induced LiCl elimination of Et₂SiCl‐NLi‐SitBu₃ in thf afforded a 2‐silaazetidine derivative by [2+2] cycloaddition of Et₂Si=N–SitBu₃ with Et₂Si(OCH=CH₂)–NH–SitBu₃. X‐ray quality crystals of this 2‐silaazetidine derivative (triclinic, space group P$\bar{1}$ ) were grown from benzene at room temperature. The starting material for this approach, Et₂SiCl–NH–SitBu₃, is water‐sensitive. Hydrolysis of Et₂SiCl‐NH‐SitBu₃ gave [tBu₃SiNH₃]Cl along with (Et₂SiO)_n oligomers. The hydro chloride [tBu₃SiNH₃]Cl could be isolated and was characterized by X‐ray crystallography (trigonal, space group P$\bar{3}$ ).     

Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization of Stilbene Monomer: Different Polymerization Behavior Depending on Halide and Aryl Group of ArPd(tBu3P)X Initiator

We report Suzuki–Miyaura coupling polymerization of tetraalkoxy‐substituted 4‐bromostilbene‐4′‐boronic acid 1 with several t‐Bu₃P‐ligated Pd initiators; this is the first example of catalyst‐transfer condensation polymerization (CTCP) of a monomer containing a carbon–carbon double bond. When o‐tolylPd(^tBu₃P)Br was used as the initiator, the o‐tolyl group was not introduced at the polymer end, but polymer with boronic acid at one end and bromine at the other was obtained. However, when we employed stilbenePd(^tBu₃P)I generated in situ from iodostilbene and Pd(^tBu₃P)G2 precatalyst, or isolated ArPd(^tBu₃P)X (Ar, X = Ph, I; o‐tolyl, I; and Ph, Br), the aryl group was introduced at the polymer end, indicating that CTCP of 1 proceeded. Therefore, the iodide and aryl group of the Pd initiator complex is crucial for CTCP of 1 . However, the molecular weight distribution of the obtained polymer was broad, possibly because coordination of the carbon–carbon double bond of 1 to ArPd(^tBu₃P)I resulted in slow initiation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 297–304     

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).