New Ga/N‐based Active Lewis Pairs,Trifunctional Ga–Ga Compounds,Reactions with Cyanamide and Dual Insertion of Isocyanate

Hydrogallation of Me₃Si–C≡C–NR'₂ with R₂Ga–H (R = tBu, CH₂tBu, iBu) yielded Ga/N‐based active Lewis pairs, R₂Ga–C(SiMe₃)=C(H)–NR'₂ ( 7 ). The Ga and N atoms adopt cis‐positions at the C=C bonds and show weak Ga–N interactions. tBu₂GaH and Me₃Si–C≡C–N(C₂H₄)₂NMe afforded under exposure of daylight the trifunctional digallium(II) compound [MeN(C₂H₄)₂N](H)C=C(SiMe₃)Ga(tBu)–Ga(tBu)C(SiMe₃)=C(H)[N(C₂H₄)₂NMe] ( 8 ), which results from elimination of isobutene and H₂ and Ga–Ga bond formation. 8 was selectively obtained from the ynamine and [tBu(H)Ga–Ga(H)tBu]₂[HGatBu₂]₂. 7a (R = tBu; NR'₂ = 2,6‐Me₂NC₅H₈) and H₈C₄N–C≡N afforded the adduct tBu₂Ga‐C(SiMe₃)=C(H)(2,6‐Me₂NC₅H₈) · N≡C–NC₄H₈ ( 11 ) with the nitrile bound to gallium. The analogous ALP with harder Al atoms yielded an adduct of the nitrile dimer or oligomers of the nitrile at room temperature. The reaction of 7a with Ph–N=C=O led to the insertion of two NCO groups into the Ga–C_vinyl bond to yield a GaOCNCN heterocycle with Ga bound to O and N atoms ( 12 ).     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXII. Die Bildung von [η2‐{tBu–P=P–SiMe3}Pt(PR3)2]aus (Me3Si)tBuP–P=P(Me)tBu2 und [η2‐{C2H4}Pt(PR3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXII. The Formation of [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂] from (Me₃Si)^tBuP–P=P(Me)^tBu₂ and [η²‐{C₂H₄}Pt(PR₃)₂] (Me₃Si)^tBuP–P = P(Me)^tBu₂ reacts with [η²‐{C₂H₄}Pt(PR₃)₂] yielding [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂]. However, there is no indication for an isomer which would be the analogue to the well known [η²‐{^tBu₂P–P}Pt(PPh₃)₂]. The syntheses and NMR data of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] and [η²‐{^tBu–P=P–SiMe₃}Pt(PMe₃)₂] as well as the results of the single crystal structure determination of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] are reported.     

Synthese und Metallierungen der tripodalen Siloxazan-Liganden tBuSi(OSiMe2NHR)3 [R = H,Me, tBu,Ph, SiMe3]

Synthesis and Metalation of Tripodal Siloxazane Ligands ^tBuSi(OSiMe₂NHR)₃ [R = H, Me, ^tBu, Ph, SiMe₃] ^tBuSi(OSiMe₂Cl)₃ ( 1 ) was generated by the condensation of tert-butylsilanetriol with dichlorodimethylsilane under elimination of HCl. A series of tripodal amines ^tBuSi(OSiMe₂NHR)₃ [R = H ( 2 ), R = Me ( 3 ), R = ^tBu ( 4 ), R = Ph ( 5 )] was synthesized by ammonolysis, aminolysis or salt elimination of 1 with primary lithium amides. 5  has been subjected to single crystal X-ray diffraction, which confirmed the triarmed amine. The siloxamine ^tBuSi(OSiMe₂NHSiMe₃)₃ ( 6 ) was generated by the reaction of 2 with three moles of chlorotrimethylsilane. The lithium amides ^tBuSi(OSiMe₂N[Li]^tBu)₃ ( 7 ), ^tBuSi(OSiMe₂N[Li]Ph)₃ ( 8 ) and ^tBuSi(OSiMe₂N[Li]SiMe₃)₃ ( 11 ) and the sodium amide ^tBuSi(OSiMe₂N[Na]^tBu)₃ ( 9 ) were obtained by the complete hydrogen–metal exchange of the amines 4 – 6 with n-butyl lithium and n-butyl sodium in hexane, respectively. The transmetalation of 7 with copper(I) chloride gave the copper amide ^tBuSi(OSiMe₂N[Cu]^tBu)₃ ( 10 ). The single crystal X-ray diffraction of the metal amides 7 , 9 and 11 shows a trifold coordination by additional interactions between each of the two metal atoms with oxygens in the siloxane groups in contrast to the copper amide 10 , which lacks such contacts. The almost isostructural metal amides 7 , 9 – 11 are monomeric and possess, similary to 5 , a pseudo three fold symmetry in the solid state. 5 and 7 crystallize in the monoclinic space group P2₁/c whereas the compounds 9 – 11 crystallize in the centrosymmetric triclinic space group P 1.     

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.     

Surprisingly Different Reaction Behavior of Alkali and Alkaline Earth Metal Bis(trimethylsilyl)amides toward Bulky N‐(2‐Pyridylethyl)‐N′‐(2,6‐diisopropylphenyl)pivalamidine

N‐(2,6‐Diisopropylphenyl)‐N′‐(2‐pyridylethyl)pivalamidine (Dipp‐N=C(tBu)‐N(H)‐C₂H₄‐Py) ( 1 ), reacts with metalation reagents of lithium, magnesium, calcium, and strontium to give the corresponding pivalamidinates [(tmeda)Li{Dipp‐N=C(tBu)‐N‐C₂H₄‐Py}] ( 6 ), [Mg{Dipp‐N=C(tBu)‐N‐C₂H₄‐Py}₂] ( 3 ), and heteroleptic [{(Me₃Si)₂N}Ae{Dipp‐N=C(tBu)‐N‐C₂H₄‐Py}], with Ae being Ca ( 2 a ) and Sr ( 2 b ). In contrast to this straightforward deprotonation of the amidine units, the reaction of 1 with the bis(trimethylsilyl)amides of sodium or potassium unexpectedly leads to a β‐metalation and an immediate deamidation reaction yielding [(thf)₂Na{Dipp‐N=C(tBu)‐N(H)}] ( 4 a ) or [(thf)₂K{Dipp‐N=C(tBu)‐N(H)}] ( 4 b ), respectively, as well as 2‐vinylpyridine in both cases. The lithium derivative shows a similar reaction behavior to the alkaline earth metal congeners, underlining the diagonal relationship in the periodic table. Protonation of 4 a or the metathesis reaction of 4 b with CaI₂ in tetrahydrofuran yields N‐(2,6‐diisopropylphenyl)pivalamidine (Dipp‐N=C(tBu)‐NH₂) ( 5 ), or [(thf)₄Ca{Dipp‐N=C(tBu)‐N(H)}₂] ( 7 ), respectively. The reaction of AN(SiMe₃)₂ (A=Na, K) with less bulky formamidine Dipp‐N=C(H)‐N(H)‐C₂H₄‐Py ( 8 ) leads to deprotonation of the amidine functionality, and [(thf)Na{Dipp‐N=C(H)‐N‐C₂H₄‐Py}]₂ ( 9 a ) or [(thf)K{Dipp‐N=C(H)‐N‐C₂H₄‐Py}]₂ ( 9 b ), respectively, are isolated as dinuclear complexes. From these experiments it is obvious, that β‐metalation/deamidation of N‐(2‐pyridylethyl)amidines requires bases with soft metal ions and also steric pressure. The isomeric forms of all compounds are verified by single‐crystal X‐ray structure analysis and are maintained in solution.     

Zur Chemie des Titan(III)-Komplexes [{(Me3Si)2N}2TiCH2SiMe2NSiMe3]–. Insertions-Reaktionen in die Ti–C-Bindung und Redox-Reaktionen

On the Chemistry of the Titanium(III) Complex [{(Me₃Si)₂N}₂TiCH₂SiMe₂NSiMe₃]^–. Insertion Reactions into the Ti–C Bond and Redox Reactions [Na(12-crown-4)₂][{(Me₃Si)₂N}₂TiCH₂SiMe₂NSiMe₃] ( 1 ) reacts with CO and the isonitrile CNCy (Cy = Cyclohexyl) under insertion into the Ti–C bond. After rearrangement planar five-membered titana(III)-heterocycles TiOCSiN and TiNCSiN with exocyclic C=CH₂ groups are formed. On the other hand, the insertion of CNBu^t leads to the primary insertion product [Na(12-crown-4)₂][{(Me₃Si)₂N}₂TiC(NBu^t)CCH₂SiMe₂NSiMe₃] ( 4 ) forming a new Ti(III)–C-bond. With NOBF₄ the anion of 1 can be oxydized to form the molecular complex [{(Me₃Si)₂N}₂TiCH₂SiMe₂NSiMe₃] ( 5 ), while with phenylacetylene redox disproportionation occurs, in the course of which the mixed ligand complex [Na(12-crown-4)₂][{(Me₃Si)₂N}₂Ti(NSiMe₃)(CH₂SiMe₂C≡C–Ph)] ( 6 ) can be isolated. 6 and the insertion products [Na(12-crown-4)₂][{(Me₃Si)₂N}₂TiOC(CH₂)SiMe₂NSiMe₃] ( 2 ) and [Na(12-crown-4)₂][{(Me₃Si)₂N}₂TiNCyC(CH₂)SiMe₂NSiMe₃] ( 3 ) are characterized by crystal structure determinations.     

Aluminum/Nitrogen Cycles and an Open Cage with Al–H and N–H Functions

The cyclic tert‐butyl‐amino alane dimer [tBu–N(H)AlH₂]₂ ( 1 ) was obtained from reaction between alane with tert‐butylamine and its boranate derivative [tBu–N(H)–Al(BH₄)₂)]₂ ( 2 ) subsequently from 1 by hydride/chloride exchange using PbCl₂ followed by reaction with LiBH₄. Both compounds form four‐membered Al₂N₂ cycles with typical Al–N bond lengths of 1.940(5) Å ( 1 ) and 1.945(5) Å ( 2 ) as found from X‐ray diffraction analysis. The tert‐butyl substituents at the nitrogen atoms may be situated at the same side of the ring (cis) or at opposite sides (trans). For compound 1 both isomers are present in solution, showing particular temperature dependent NMR shifts. In the solid both compounds 1 and 2 adopt the trans arrangement. When 1 is reacted with PbCl₂ in half of the molarity ratio used for 2 , surprisingly the novel compound 3 , a zwitterion, can be obtained: [(tBu–N)(Al–H)₃(tBu–N(H))₃Cl((H)N–tBu)₃(Al–H)₂(Al–Cl)(N–tBu)]⁺[(tBu–N)(tBu–N(H))(AlCl₂)₂]^–. X‐ray structure analysis reveals that the anion is made of a tert‐butyl amino aluminum dichloride dimer (central Al₂N₂ ring) with one of the two nitrogen atoms being deprotonated. The cationic counterpart consists of three entities: (i) There is a first seco‐norcubane like Al₃N₄ basket with tert‐butyl groups at the nitrogen atoms, two hydride and one chloride ligand at the aluminum atoms and three hydrogen atoms on the open side of the basket, all pointing in the same direction; (ii) There is a second similar Al₃N₄ basket with the same substituent pattern except that all aluminum atoms have exclusively hydrogen ligands; (iii) Both baskets coordinate a central chloride through the six protons at the open nitrogen face of the baskets in such a way that the chloride lies in the center of a H₆ trigonal anti‐prism [mean H–Cl–H = 56.1(9)°]. As each of the open cages has a positive charge the overall charge by combination with the chloride adds to +1. The structure of the cationic part of 3 is unprecedented in AlN polycycles.     

An N‐Heterocyclic Silylene‐Stabilized Digermanium(0) Complex

The synthesis of an N‐heterocyclic silylene‐stabilized digermanium(0) complex is described. The reaction of the amidinate‐stabilized silicon(II) amide [LSiN(SiMe₃)₂] ( 1 ; L=PhC(NtBu)₂) with GeCl₂?dioxane in toluene afforded the Si^II–Ge^II adduct [L{(Me₃Si)₂N}Si→GeCl₂] ( 2 ). Reaction of the adduct with two equivalents of KC₈ in toluene at room temperature afforded the N‐heterocyclic carbene silylene‐stabilized digermanium(0) complex [L{(Me₃Si)₂N}Si→ Ge?Ge←Si{N(SiMe₃)₂}L] ( 3 ). X‐ray crystallography and theoretical studies show conclusively that the N‐heterocyclic silylenes stabilize the singlet digermanium(0) moiety by a weak synergic donor–acceptor interaction.     

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).     

Lithiated Stannasilanes – Building Blocks for Monocyclic Si–Sn Rings

Dilithiated di(stannyl)oligosilanes (^tBu₂Sn(Li)– (SiMe₂)_n–Sn(Li)^tBu₂; 4 , n = 2; 5 , n = 3) were synthesized by the reaction of lithium diisopropylamide (LDA) with the α,ω‐hydrido tin substituted oligosilanes (^tBu₂Sn(H)– (SiMe₂)_n–Sn(H)^tBu₂; 1 , n = 2; 2 , n = 3). Surprisingly, the reaction of 1 and 3 (^tBu₂Sn(H)–(SiMe₂)₄–Sn(H)^tBu₂) with LDA resulted not in the formation of the lithiated compound, but what one can find is the formation of the 5,5‐ditert.butyl‐octamethyl‐1,2,3,4‐tetrasila‐5‐stannacyclopentane ( 8 ) (n = 4) in addition to the expected product 4 (n = 4) and the 3,3,6,6‐tetratert.butyl‐octamethyl‐1,2,4,5‐tetrasila‐3,6‐distannacyclohexane ( 7 ) (n = 3). Reactions of 4 and 5 with dimethyl and diphenyldichlorosilanes yielding monocyclic Si–Sn derivatives ( 9 – 11 ) are also discussed. The solid‐state structures of 7 and 11 were determined by X‐ray crystallography.     

Amidometallate von Seltenerdelementen. Synthese und Kristallstrukturen von [Na(12-Krone-4)2][M{N(SiMe3)2}3(OSiMe3)] (M = Sm,Yb), [Na(THF)3Sm{N(SiMe3)2}3(C≡C–Ph)], [Na(THF)6][Lu2(μ-NH2)(μ-NSiMe3){N(SiMe3)2}4] sowie von [NaN(SiMe3)2(THF)]2. Anwendungen der Seltenerdkomplexe als Polymerisationskatalysatoren

Amido Metalates of Rare Earth Elements. Syntheses and Crystal Structures of [Na(12-crown-4)₂][M{N(SiMe₃)₂}₃(OSiMe₃)] (M = Sm, Yb), [Na(THF)₃Sm{N(SiMe₃)₂}₃(C≡C–Ph)], [Na(THF)₆][Lu₂(μ-NH₂)(μ-NSiMe₃){N(SiMe₃)₂}₄], and of [NaN(SiMe₃)₂(THF)]₂. Applications of Rare Earth Metal Complexes as Polymerization Catalysts The amido silyloxy complexes [Na(12-crown-4)₂][M{N(SiMe₃)₂}₃(OSiMe₃)] with M = Sm ( 1 a ), Eu ( 1 b ), Yb ( 1 c ), and Lu ( 1 d ) were obtained from the trisamides M[N(SiMe₃)₃]₃ and NaOSiMe₃ in n-hexane in the presence of 12-crown-4; they form yellow to orange-red crystals, of which 1 a and 1 c were characterized crystallographically. The complexes crystallize isotypically with one another in the monoclinic space group I2/a with eight formula units per unit cell. The metal atoms of the complex anions are tetrahedrally coordinated by the three nitrogen atoms of the N(SiMe₃)₂^– ligands and by the oxygen atom of the OSiMe₃^– ligand. With 172.4° for 1 a and 179.3° for 1 c the bond angles M–O–Si are practically linear. With ethynylbenzene in the presence of NaN(SiMe₃)₂ in tetrahydrofuran the trisamides M[N(SiMe₃)₂]₃ react under formation of the complexes [Na(THF)₃M{N(SiMe₃)₂}₃ · (C≡C–Ph)] with M = Ce ( 2 a ), Sm ( 2 b ), and Eu ( 2 c ), of which 2 b was characterized crystallographically (monoclinic, space group P2₁/n, Z = 4). 2 b forms an ion pair in which the terminal carbon atom of the C≡C–Ph^– ligand is connected with the samarium atom of the Sm[N(SiMe₃)₂]₃ group and the sodium ion is side-on connected with the acetylido group. According to the crystal structure determination (space group P2₁2₁2₁, Z = 4) [Na(THF)₆][Lu₂(μ-NH₂)(μ-NSiMe₃) · {N(SiMe₃)₂}₄] ( 3 ), which is formed as a by-product, consists of [Na(THF)₆]⁺ ions and dimeric anions, in which the lutetium atoms are connected to form a planar Lu₂N₂ four-membered ring via a μ-NH₂ bridge with average Lu–N distances of 227.2 pm and via a μ-NSiMe₃ bridge of average Lu–N distances of 218.5 pm. According to the crystal structure determination (space group P 1, Z = 1) [NaN(SiMe₃)₂(THF)]₂ ( 4 ) forms centrosymmetric dimeric molecules with Na–N distances of the Na₂N₂ four-membered ring of 239.9 pm and distances Na–O of the terminally bonded THF molecules which are 226.7 pm. The vinylic polymerization of methylmethacrylate (MMA) catalyzed by 1 c resulted in high molecular weight polymethylmethacrylate (PMMA) with moderate yields. The reaction of 1 a or 2 b with MMA did not give PMMA. Insoluble polynorbornene was obtained in low yields by reaction of norbornene/methylaluminoxane (MAO) with 1 a , 1 c , or 2 b . The ring opening polymerization of ϵ-caprolacton or δ-valerolacton catalyzed by 2 b resulted in corresponding polylactones in quantitative yields.     

Neue mehrkernige Indium–Stickstoff‐Verbindungen – Synthese und Kristallstrukturen von [In4X4(NtBu)4] (X = Cl,Br, I) und [In3Br4(NtBu)(NHtBu)3]

New Polynuclear Indium Nitrogen Compounds – Synthesis and Crystal Structures of [In₄X₄(N^tBu)₄] (X = Cl, Br, I) and [In₃Br₄(N^tBu)(NH^tBu)₃] The reaction of the indium trihalides InX₃ (X = Cl, Br, I) with LiNH^tBu in THF leads to the In₄N₄‐heterocubanes [In₄X₄(N^tBu)₄] (X = Cl 1 , Br 2 , I 3 ). Additionally [In₃Br₄(N^tBu)(NH^tBu)₃] ( 4 ) was obtained as a by‐product in the synthesis of 2 . 1 – 4 have been characterized by x‐ray crystal structure analysis. 1 – 3 consist of In₄N₄ heterocubane cores with an alternating arrangement of In and N atoms. The In atoms are coordinated nearly tetrahedrally by three N‐atoms and a terminal halogen atom. 4 contains a tricyclic In₃N₄ core which can be formally derived from an In₄N₄‐heterocubane by removing one In atom.     

Moleküle mit ungewöhnlich langen N(sp2)–Si(sp3)-Bindungen: Synthese und Kristallstrukturen von 1,2-Benzoldisulfonylaminosilanen

Polysulfonylamines. XCIV. Molecules with Unusually Long N(sp²)–Si(sp³) Bonds: Synthesis and Crystal Structures of 1,2-Benzenedisulfonylaminosilanes The following compounds were obtained by metathesis of silver 1,2-benzenedisulfonimide (AgZ) with the appropriate chlorosilanes: ZSiMe₃ ( 4 ), ZSiⁿPr₃, ZSiMe₂ⁿBu, ZSiMe₂(CMe₂–CHMe₂) ( 7 ), (Z)₂SiMe₂ ( 8 ). In the crystal structures of 4 (monoclinic, space group P2₁/n), 7 (monoclinic, P2₁/c) and 8 (monoclinic, P2₁/n), which were determined by low-temperature X-ray diffraction, the molecules adopt the N-silyl form and display unusually long bonds between the trigonal-planar N and the tetrahedrally coordinated Si atoms ( 4 : 182.6, 7 : 184.1, 8 : 177.8 and 180.5 pm). For 7 in CDCl₃ solution, ¹H and ¹³C NMR data indicate N,O-silylotropy. The solid state structures of molecules 4 and 7 strongly suggest that the N–Si bond lengthening in N,N-disulfonylated aminosilanes is mainly induced by the π-acceptor character of the SO₂ groups and not by the occasionally observed coordination expansion of the Si atom through short intramolecular O…Si contacts.     

Synthetic and Structural Studies on the Cyclic Bis(amino)stannylenes Sn[(NR)2C10H6‐1, 8] and their Reactions with SnCl2 or Si[(NCH2But)2C6H4‐1, 2] (R = SiMe3 or CH2But)

Treatment of {HNR}₂C₁₀H₆‐1, 8 [R = SiMe₃ ( 1 ), CH₂Bu^t ( 2 )] with Sn[N(SiMe₃)₂]₂ afforded the cyclic stannylene Sn[{NR}₂C₁₀H₆‐1, 8] [R = SiMe₃ ( 3 ), CH₂Bu^t ( 4 )]. From 3 and SnCl₂ in THF and crystallisation from toluene, the product was the crystalline tetracyclic compound ( 5 ) as the (toluene)_0.5‐solvate. Reaction of 4 with the silylene Si[(NCH₂Bu^t)₂C₆H₄‐1, 2] ( 6 ) [abbreviated as Si(NN)] in benzene and crystallisation in presence of Et₂O furnished the crystalline tricyclic complex Sn[{Si(NCH₂Bu^t)₂C₆H₄‐1′, 2′}₂‐{(NCH₂Bu^t)₂C₁₀H₆‐1, 8}] ( 7 ) as the Et₂O‐solvate. Complex 5 slowly dissociated into its factors 3 and SnCl₂ in toluene, but rapidly in THF. Solutions of 7 in C₆D₆, C₇D₈ or THF‐d₈, studied by multinuclear, variable temperature NMR spectroscopy, revealed the presence of an equilibrium between 8 (an isomer of 7 , in which the skeletal atoms of the eight‐membered ring were , rather than the of 7 ) and 4 + 2 Si(NN), with 8 dominant in PhMe but not in THF; additionally 8 was shown to be fluxional and solutions of 8 in C₆D₆ or C₇D₈ decomposed to give the silane Si(NN)[(NCH₂Bu^t)₂C₁₀H₆‐1, 8], 6 and Sn metal. The X‐ray structures of 3 , 5 and 7 are presented.     

8‐Amidoquinoline, 8‐(Trialkylsilylamido)quinoline, 2‐Pyridylmethylamide,and (2‐Pyridylmethyl)(trialkylsilyl)amide Complexes of Gallium

Lithium 8‐amidoquinoline ( 1 ) and lithium 8‐(trialkylsilylamido)quinoline [SiMe₂tBu ( 2 ), SiiPr₃ ( 3 )] react with dimethylgallium chloride to the metathesis products dimethylgallium 8‐amidoquinoline ( 4 ) as well as dimethylgallium 8‐(trialkylsilylamido)quinoline [SiMe₂tBu ( 5 ), SiiPr₃ ( 6 )]. The gallium atoms are in distorted tetrahedral environments. During the synthesis of 5 , orange dimethylgallium 2‐butyl‐8‐(tert‐butyldimethylsilylamido)quinoline ( 7 ) was found as by‐product. The metathesis reactions of Me₂GaCl with LiN(R)CH₂Py (Py = 2‐pyridyl) yield the corresponding 2‐pyridylmethylamides Me₂Ga‐N(H)CH₂Py ( 8 ), Me₂Ga‐N(SiMe₂tBu)CH₂Py ( 9 ) and Me₂Ga‐N(SiiPr₃)CH₂Py ( 10 ). In these complexes the gallium atoms show a distorted tetrahedral coordination sphere. However, derivative 8 crystallizes dimeric with bridging amido units whereas in 9 and 10 the 2‐pyridylmethylamido moieties act as bidentate ligands leading to monomeric molecules.     

Synthesis of a Metallo‐Iminosilane via a Silanone–Metal π‐Complex

Facile oxygenation of the acyclic amido‐chlorosilylene bis(N‐heterocyclic carbene) Ni⁰ complex [{N(Dipp)(SiMe₃)ClSi:→Ni(NHC)₂] ( 1 ; Dipp=2,6‐ⁱPr₂C₆H₄; N‐heterocyclic carbene=C[(ⁱPr)NC(Me)]₂) with N₂O furnishes the first Si‐metalated iminosilane, [DippN=Si(OSiMe₃)Ni(Cl)(NHC)₂] ( 3 ), in a rearrangement cascade. Markedly, the formation of 3 proceeds via the silanone (Si=O)–Ni π‐complex 2 as the initial product, which was predicted by DFT calculations and observed spectroscopically. The Si=O and Si=N moieties in 2 and 3 , respectively, show remarkable hydroboration reactivity towards H−B bonds of boranes, in the former case corroborating the proposed formation of a (Si=O)–Ni π‐complex at low temperature.     

Synthesis and Reactivity of 2,2,4,4–Tetrakis(tri–tert–butoxysilanethiolato)–1,3,2,4–dithiadistannetane – Crystal and Molecular Structures of Two Polymorphic Forms

The title compound, [Sn(μ–S){SSi(O^tBu)₃}₂]₂ ( 1 ), containing four–coordinated tin(IV), crystallizes in two polymorphic modifications. The orthorhombic 1a –form has been obtained in the reaction of (^tBuO)₃SiSH and Et₃N with SnCl₂, whereas the triclinic 1b –form in the reaction with SnCl₄ as substrate. The crystal and molecular structures of both polymorphs ( 1a as a redetermination) have been determined by a single–crystal X–ray diffraction study at room temperature. The title compound was shown to react with ammonia and ammonia complexes of some d–block metal cations giving products of Sn–S bond cleavage.     

[Li(12-Krone-4){(Me3Si)2N}2TiCH2SiMe2NSiMe3] – ein Ionenpaar mit gestreckter Li–C–Ti-Achse

[Li(12-Crown-4){(Me₃Si)₂N}₂TiCH₂SiMe₂NSiMe₃] – an Ion-Pair with a Linear Li–C–Ti-Axis The title compound ( 1 ) has been prepared from Ti[N(SiMe₃)₂]₃ and n-butyllithium in OEt₂/n-hexane in the presence of 12-crown-4. Smaragd-green single crystals of 1 · C₇H₈ which were suitable for X-ray crystallography were formed from toluene solutions at –18 °C. According to the crystal structure determination 1 forms ion pairs between the lithium atom and the CH₂-carbon atom which is member of a planar Ti–C–Si–N heterocycle. The coordination geometry of the Li–C–Ti axis is linear (bond angle 172.8° in average of the two symmetry independent species) with coordination number five at the CH₂-carbon atom.     

Darstellung,Charakterisierung und Reaktionsverhalten von Natrium‐ und Kaliumhydridosilylamiden R2(H)Si—N(M)R′ (M = Na,K) — Kristallstruktur von [(Me3C)2(H)Si—N(K)SiMe3]2·THF

Preparation, Characterization and Reaction Behaviour of Sodium and Potassium Hydridosilylamides R₂(H)Si—N(M)R′ (M = Na, K) — Crystal Structure of [(Me₃C)₂(H)Si—N(K)SiMe₃]₂ · THF The alkali metal hydridosilylamides R₂(H)Si—N(M)R′ 1a‐Na — 1d—Na and 1a‐K — 1d‐K ( a : R = Me, R′ = CMe₃; b : R = Me, R′ = SiMe₃; c : R = Me, R′ = Si(H)Me₂; d : R = CMe₃, R′= SiMe₃) have been prepared by reaction of the corresponding hydridosilylamines 1a — 1d with alkali metal M (M = Na, K) in presence of styrene or with alkali metal hydrides MH (M = Na, K). With NaNH₂ in toluene Me₂(H)Si—NHCMe₃ ( 1a ) reacted not under metalation but under nucleophilic substitution of the H(Si) atom to give Me₂(NaNH)Si—NHCMe₃ ( 5 ). In the reaction of Me₂(H)Si—NHSiMe₃ ( 1b ) with NaNH₂ intoluene a mixture of Me₂(NaNH)Si—NHSiMe₃ and Me₂(H)Si—N(Na)SiMe₃ ( 1b‐Na ) was obtained. The hydridosilylamides have been characterized spectroscopically. The spectroscopic data of these amides and of the corresponding lithium derivatives are discussed. The ²⁹Si‐NMR‐chemical shifts and the ²⁹Si—¹H coupling constants of homologous alkali metal hydridosilylamides R₂(H)Si—N(M)R′ (M = Li, Na, K) are depending on the alkali metal. With increasing of the ionic character of the M—N bond M = K > Na > Li the ²⁹Si‐NMR‐signals are shifted upfield and the ²⁹Si—¹H coupling constants except for compounds (Me₃C)(H)Si—N(M)SiMe₃ are decreased. The reaction behaviour of the amides 1a‐Na — 1c‐Na and 1a‐K — 1c‐K was investigated toward chlorotrimethylsilane in tetrahydrofuran (THF) and in n‐pentane. In THF the amides produced just like the analogous lithium amides the corresponding N‐silylation products Me₂(H)Si—N(SiMe₃)R′ ( 2a — 2c ) in high yields. The reaction of the sodium amides with chlorotrimethylsilane in nonpolar solvent n‐pentane produced from 1a‐Na the cyclodisilazane [Me₂Si—NCMe₃]₂ ( 8a ), from 1b‐Na and 1‐Na mixtures of cyclodisilazane [Me₂Si—NR′]₂ ( 8b , 8c ) and N‐silylation product 2b , 2c . In contrast to 1b‐Na and 1c‐Na and to the analogous lithium amides the reaction of 1b‐K and 1c‐K with chlorotrimethylsilane afforded the N‐silylation products Me₂(H)Si—N(SiMe₃)R′ ( 2b , 2c ) in high yields. The amide [(Me₃C)₂(H)Si—N(K)SiMe₃]₂·THF ( 9 ) crystallizes in the space group C2/c with Z = 4. The central part of the molecule is a planar four‐membered K₂N₂ ring. One potassium atom is coordinated by two nitrogen atoms and the other one by two nitrogen atoms and one oxygen atom. Furthermore K···H(Si) and K···CH₃ contacts exist in 9 . The K—N distances in the K₂N₂ ring differ marginally.     

Zirconium Complexes of Two Different Iminopyrrolyl Ligands – Syntheses and Structures

The reaction involving N‐aryliminopyrrolyl ligand, 2‐((p‐Me‐C₆H₃N=CMe)–C₄H₃NH) ( 1a ) (Imp^Me‐H), and Zr(OtBu)₄ in a 2:1 molar ratio in toluene at 90 °C afforded the corresponding bis(iminopyrrolyl) complex of zirconium, [(Imp^Me)₂Zr(OtBu)₂] ( 2a ) having two bidentate iminopyrrole groups in the coordination sphere. In contrast, the bulkier 2‐((2,6‐iPr₂C₆H₃N=CH)–C₄H₃NH) ( 1b ) (Imp^Dipp‐H) and Zr(OtBu)₄ in a 1:1 molar ratio under the same condition yielded the corresponding mono(iminopyrrolyl) complex of zirconium, [(Imp^Dipp)Zr(OtBu)₃(THF)] ( 2b ), which contains only one bidentate iminopyrrole moiety in the coordination sphere. Both complexes were characterized by single‐crystal X‐ray diffraction analysis. The solid‐state structures reveal that the bulky iminopyrrole ligands cause a steric crowding around the zirconium ion along with three tert‐butoxide ligands attached to the central metal atom.