Schrittweise Darstellung von verzweigten tripodalen Chlor‐Methyl‐Siloxanen der allgemeinen Formel tBuSi[{OSiMe2}yOSiMe3–xClx]3 [x = 0–3; y = 0–2] sowie Synthese der Silanole tBuSi[(OSiMe2)xOH]3 [x = 1, 2] und des bicyclischen Siloxans tBuSi(OSiMe2O)3SitBu

The branched tripodal chloro‐methyl‐siloxanes of the general formula tBuSi[{OSiMe₂}_yOSiMe_3–xCl_x]₃ [x = 0–3; y = 0–2] were synthesized, starting with tert‐Butyl‐trisilanol ( 1 ). The treatment of 1 with the chloro‐methyl‐silanes (Me_3–xSiCl_x+1) (x = 0–3) in the presence of triethylamine leads to the compounds tBuSi(OSiMe₂Cl)₃ ( 2 ), tBuSi(OSiMeCl₂)₃ ( 3 ) and tBuSi(OSiCl₃)₃ ( 4 ). The siloxanes 2 – 4 are colourless oily liquids, which can be purified by distillation. Their yields decrease with the number of chloro substituents. In the reaction of compound 2 with three equivalents of water the silantriol tBuSi(OSiMe₂OH)₃ ( 5 ) is generated which is used to create the branched tripodal chloro‐methyl‐siloxanes tBuSi(OSiMe₂OSiMe₃)₃ ( 6 ), tBuSi(OSiMe₂OSiMe₂Cl)₃ ( 7 ), tBuSi(OSiMe₂OSiMeCl₂)₃ ( 9 ) and tBuSi(OSiMe₂OSiCl₃)₃ ( 10 ). Compound ( 7 ) is only a side product with a yield of 25 %., The cyclic tBuSi[{(OSiMe₂)₂Cl}(OSiMe₂)₃O] ( 8 ) can be isolated and characterised. The transformation of the compound tBuSi(OSiMe₂OSiMe₂Cl)₃ ( 7 ) into the trisilanol tBuSi(OSiMe₂OSiMe₂OH)₃ ( 11 ) allows to prepare the tripodale siloxane tBuSi(OSiMe₂OSiMe₂OSiMe₃)₃ ( 12 ) in good yields., The reaction of tBuSi(OSiMe₂Cl)₃ ( 2 ) with tert‐butyl trisilanol 1 leads to the formation of bicyclic tBuSi(OSiMe₂O)₃SitBu ( 13 ). An X‐ray structure determination on 13 reveals a [3.3.3]‐bicycle with a C₃ axis, which crystallizes in the cubic crystal system in the space group Pa . The reported compounds 2 – 13 were characterised by NMR‐ and IR spectroscopy ( 5 , 11 ) and show correct elemental analyses. The ²⁹Si‐NMR‐data of the compounds show interesting trends with respect to the Si–O chain length and the chloro substistuents.     

Neue Alkalimetall‐Koordinationen durch chelatisierende Siloxazaneinheiten in Verbindungen der Formel [X–N–SiMe2–O–SiMe2–N–X]2M4

New Alkali Metal Coordinations by Chelating Siloxazane Units within Molecules of the General Formula [X–N–SiMe₂–O–SiMe₂–N–X]₂M₄ New solvent free alkali metal amides with Si–O–Si bridges of the general formula [X–N–SiMe₂–O–SiMe₂–N–X]₂M₄ (X = ^tBu ( 1 ), SiMe₃ ( 2 ), SiMe₂^tBu ( 3 ) with M = Li; X = ^tBu ( 4 ), SiMe₃ ( 5 ) with M = Na; X = ^tBu mit M = K, Li ( 6 )) have been synthesised and characterised by spectroscopic means. X‐ray structure analyses of the six metal derivatives reveal a common structural principle: the four metal atoms within the molecules are incorporated between two molecular halfs and form the bonding links between the two parts. The central molecular skeleton of the molecular halfs consists of a zig‐zag chain N–Si–O–Si–N. This chain is connected to the second one either ideally or approximately by S₄ (4) symmetry. The point symmetries within the crystal are either S₄ (4) (compounds 2 and 4 ), C₂ (2) (compound 6 ), and C₁ (1) (compounds 3 and 5 ). Compound 1 is special in different aspects: the molecule has the high crystallographic point symmetry D_2d (4m2) and the lithium atoms occupy split atom positions (in a similar way as in compound 2 ). The high symmetry of 1 as well as the split atom positions of the lithium atoms are a consequence of dynamics within the crystal.     

Synthesis,structure and ethylene polymerization of group 4 complexes with phosphinoamide ligands

Group 4 complexes containing diphosphinoamide ligands [Ph₂PNR]₂MCl₂ (3: R = ^tBu, M = Ti; 4: R = ^tBu, M = Zr; 5: R = Ph, M = Ti; 6: R = Ph, M = Zr) were prepared by the reaction of MCl₄ (M = Ti; Zr) with the corresponding lithium phosphinoamides in ether or THF. The structure of [Ph₂PN^tBu]₂TiCl₂ (3) was determined by X‐ray crystallography. The phosphinoamides functioned as η²‐coordination ligands in the solid state and the Ti? N bond length suggests it is a simple single bond. In the presence of modified methylaluminoxane or i‐Bu₃Al/Ph₃BC(C₆F₅)₄, catalytic activity of up to 59.5 kg PE/mol cat h bar was observed. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthese und Charakterisierung der Siloxialane [H2AlOSiMe3]n und [HAl(OtBu)(OSiMe3)]2 sowie Redoxreaktionen von [H2AlOSiMe3]n und [H2AlOtBu]2 mit einem Zinn(II)‐amid

Synthesis and Characterisation of the Siloxialanes [H₂AlOSiMe₃]_n and [HAl(O^tBu)(OSiMe₃)]₂ as well as the Use of [H₂AlOSiMe₃]_n and [H₂AlO^tBu]₂ as Reducing Agents for a Tin(II) Amide Following the synthesis of [H₂AlO^tBu]₂ ( 1 ) and [HAl(O^tBu)₂]₂ ( 2 ) the siloxialane [H₂AlOSiMe₃]_n ( 3 ) was synthesized and has been subject to single crystal X‐ray analysis for the first time. The molecule 3 is tetrameric (n = 4) in solution and polymeric (n = ∞) in the solid state. 3 is also obtained together with the siloxide [Al(OSiMe₃)₃]₂ ( 5 ) by the reaction of the aluminiumhydride with the double molar amount of trimethylsilanol. The expected monohydride [HAl(OSiMe₃)₂]₂ ( 4 ) was not formed. The heteroleptic monohydride [HAl(O^tBu)(OSiMe₃)]₂ ( 6 ) was synthesized by the reaction of 3 with an equimolar amount of tert‐butanol and was also generated by the addition of trimethylsilanol to an equimolar amount of the alkoxialane [H₂AlO^tBu]₂ ( 1 ). Compound 6 was characterized by single crystal X‐ray diffraction analysis. Additionally we investigated the reducing force of the dihydrides 1 and 3 towards the cyclic diazastannylene Me₂Si(N^tBu)₂Sn ( 7 ). In the course of this reaction Sn^II in 7 was reduced to elementary tin whereas the hydrides were oxidized to hydrogene. Tin is obtained in its β‐form as found by powder‐X‐ray diffraction. The shapes of the metal precipitates (porous, sponge‐like pieces or nanoscaled powders) depend on the conditions of reactions. Besides the elements the spirocyclic aminoalkoxialane [Me₂Si(N^tBu)₂AlO^tBu]₂ ( 8 ) or aminosiloxialane [Me₂Si(N^tBu)₂AlOSiMe₃]₂ ( 9 ) are formed. Structural details of the molecules 8 and 9 can be derived from single crystal X‐ray analyses.     

Recent development of aminophosphine chalcogenides and boranes as ligands in s-block metal chemistry

The coordination chemistry of the aminophosphine chalcogenide ligands [Ph₂P(O)NHR], [Ph₂P(S)NHR], and [Ph₂P(Se)NHR] (R = 2,6-Me₂C₆H₃,^tBu, CHPh₂, CPh₃) or corresponding borane derivative [Ph₂P(BH₃)NHR] toward group 1 and 2 metals is reviewed. The structural characterization of a huge number of mono- and bis-aminophosphine chalcogenide/borane complexes with group 1 and 2 metals—in most cases lithium, sodium, potassium, magnesium, calcium, strontium, and barium complexes—reveals a poly-metallacyclic motif in each case. The coordination takes place from adjacent chalcogen/borane and nitrogen as donor atom or group of the ligand confirming the direct bond between metal and chalcogen/borane to develop homoleptic and heteroleptic complexes. The heteroleptic group 2 metal complexes were used as pre-catalysts in hydrophosphination and hydroamination reactions. Similarly, aminophosphine chalcogenide alkaline earth metal complexes were used in the catalytic ring-opening polymerization (ROP) study of ?-caprolactone.     

Homoleptische Amide von Zink,Cadmium und Quecksilber

Homoleptic Amides of Zinc, Cadmium, and Mercury ZnCl₂, CdCl₂ and HgCl₂ react with the lithium salts ( 1 a–5 a ) of the sterically demanding secundary amines HN(SiMe₃)Ph ( 1 ), HN(SiMe₃)C₆H₃Me₂‐2,6 ( 2 ), HN(SiMe₃)C₆H₃ⁱPr₂‐2,6 ( 3 ), HN(SiMe₃)C₆H₃^tBu₂‐2,5 ( 4 ), and HN(SiMe₂NMe₂)C₆H₃ⁱPr₂‐2,6 ( 5 ) yielding the corresponding homoleptic metal amides Zn[N(SiMe₂R′)R]₂ ( 1 b–5 b ), Cd[N(SiMe₂R′)R]₂ ( 1 c , 5 c ), and Hg[N(SiMe₂R′)R]₂ ( 1 d–5 d ), respectively. Except the dimeric {Zn[N(SiMe₃)Ph]₂}₂ ( 1 b ), all complexes are monomeric. The compounds were characterized by elemental analyses, molecular weight determinations, NMR and mass spectra. Furthermore, the zinc amides ( 1 b–5 b ) and the mercury amides 1 d–3 d and 5 d were characterized by single crystal X‐ray structure analysis. Except 1 b and 5 b , they show a linear N–M–N arrangement.     

1‐Azaallyl Complexes of NiII,PdII, and TiIII

The metal complexes [Ni{N(Ar)C(R)C(H)Ph}₂) ( 2 ) (Ar = 2,6‐Me₂C₆H₃, R = SiMe₃), [Ti(Cp₂){N(R)C(Bu^t)C(H)R}] ( 3 ), M{N(R)C(Bu^t)C(H)R}I [M = Ni ( 4 a ) or Pd ( 4 b )] and [M{N(R)C(Bu^t)C(H)R}I(PPh₃)] [M = Ni ( 5 a ) or Pd ( 5 b )] have been prepared from a suitable metal halide and lithium precursor of ( 2 ) or ( 3 ) or, alternatively from [M(LL)₂] (M = Ni, LL = cod; M = Pd, LL = dba) and the ketimine RN = C(Bu^t)CH(I)R ( 1 ). All compounds, except 4 were fully characterised, including the provision of X‐ray crystallographic data for complex 5 a .     

Four‐Membered Heterometallacyclic d0 and d1 Complexes of Group 4 Metallocenes with Amidato Ligands

A study of the coordination chemistry of different amidato ligands [(R)N?C(Ph)O] (R=Ph, 2,6‐diisopropylphenyl (Dipp)) at Group 4 metallocenes is presented. The heterometallacyclic complexes [Cp₂M(Cl){κ²‐N,O‐(R)N?C(Ph)O}] M=Zr, R=Dipp ( 1 a ), Ph ( 1 b ); M=Hf, R=Ph ( 2 )) were synthesized by reaction of [Cp₂MCl₂] with the corresponding deprotonated amides. Complex 1 a was also prepared by direct deprotonation of the amide with Schwartz reagent [Cp₂Zr(H)Cl]. Salt metathesis reaction of [Cp₂Zr(H)Cl] with deprotonated amide [(Dipp)N?C(Ph)O] gave the zirconocene hydrido complex [Cp₂M(H){κ²‐N,O‐(Dipp)N?C(Ph)O}] ( 3 ). Reaction of 1 a with Mg did not result in the desired Zr(III) complex but in formation of Mg complex [(py)₃Mg(Cl) {κ²‐N,O‐(Dipp)N?C(Ph)O}] ( 4 ; py=pyridine). The paramagnetic complexes [Cp′₂Ti{κ²‐N,O‐(R)N?C(Ph)O}] (Cp′=Cp, R=Ph ( 7 a ); Cp′=Cp, R=Dipp ( 7 b ); Cp′=Cp*, R=Ph ( 8 )) were prepared by the reaction of the known titanocene alkyne complexes [Cp₂′Ti(η²‐Me₃SiC₂SiMe₃)] (Cp′=Cp ( 5 ), Cp′=Cp* ( 6 )) with the corresponding amides. Complexes 1 a , 2 , 3 , 4 , 7 a , 7 b , and 8 were characterized by X‐ray crystallography. The structure and bonding of complexes 7 a and 8 were also characterized by EPR spectroscopy.     

The Iminoborane tBuB≡NtBu as a Dipolarphile in (2+3) Cycloadditions

The iminoborane tBuB≡NtBu and the diazomethane tBuCH=N₂ give the (2+3) cycloadduct [—HC(tBu)—N=N—N(tBu)=B(tBu)—] in a 1:1 reaction and the seven‐membered ring [—C(tBu)=N—NH—N(tBu)=B(tBu)—N(tBu)=B(tBu)—] in a 2:1 reaction. The (2+3) cycloadduct decomposes above 0 °C to give the seven‐membered ring, N₂, and HC(tBu)=N—N=CH(tBu) in the ratio 2:1:1. The borane tBuB≡NtBu and organic azides R″N₃ yield the (2+3) cycloadducts [—R″N—N=N—N(tBu)=B(tBu)—] (R″ = Me, Et, Pr, Bu, iBu, sBu, C₅H₁₁, c‐C₅H₉, c‐C₆H₁₁, Bzl, EtOOC).     

Intramolecular Metal⋅⋅⋅π‐Arene Interactions in Neutral and Cationic Main Group Compounds

The role of intramolecular metal???π‐arene interactions has been investigated in the solid‐state structures of a series of main group compounds supported by the bulky amide ligands, [N(^tBuAr^≠)(SiR₃)]^? (^tBuAr^≠=2,6‐(CHPh₂)₂‐4‐tBuC₆H₂, R=Me, Ph). The lithium and potassium amide salts showed different patterns of solvation and demonstrated that the SiPh₃ substituent is able to be involved in stabilizing the electrophilic metal. These group 1 metal compounds served as ligand transfer reagents to access a series of bismuth(III) halides. Chloride extraction from Bi(N{^tBuAr^≠}{SiPh₃})Cl₂ using AlCl₃ afforded the 1:1 salt [Bi(N{^tBuAr^≠}{SiPh₃})Cl][AlCl₄]. This was accompanied by a significant rearrangement of the stabilizing π‐arene contacts in the solid‐state. Attempted preparation of the corresponding tetraphenylborate salt resulted in phenyl‐transfer and generation of the neutral Bi(N{^tBuAr^≠}{SiPh₃})(Ph)Cl.     

Synthesis and Structural Characterization of Some Novel Trialkylsilyl‐substituted Lithium Benzyl Complexes [Li(tmeda)][CHRSiMe2R′] (R = Ph, 3,5‐Me2C6H3; R′ = Me,tBu, Ph)

The reactions of PhCH₂SiMe₃ ( 1 ), PhCH₂SiMe₂^tBu ( 2 ), PhCH₂SiMe₂Ph ( 3 ), 3,5‐Me₂C₆H₃CH₂SiMe₃ ( 4 ), and 3,5‐Me₂C₆H₃CH₂SiMe₂^tBu ( 5 ) with ⁿBuLi in tetramethylethylenediamine (tmeda) afford the corresponding lithium complexes [Li(tmeda)][CHRSiMe₂R′] (R, R′ = Ph, Me ( 6 ), Ph, ^tBu ( 7 ), Ph, Ph ( 8 ), 3,5‐Me₂C₆H₃, Me ( 9 ), and 3,5‐Me₂C₆H₃, ^tBu ( 10 )), respectively. The new compounds 5 , 7 , 8 , 9 and 10 have been characterized by ¹H and ¹³C NMR spectroscopy, compounds 7 , 8 and 9 also by X‐ray structure analysis.     

Synthese und Struktur von Vanadium(III)- und Vanadium(IV)-silanolaten

Synthesis and Structures of Vanadium(III) and Vanadium(IV) Silanolates The syntheses of the new and partially known vanadium(III)-silanolate complexes [{V(OSiMe^t₂Bu)₃}₂(THF)] ( 1 ), [Li(THF)₂V(OSiMe^t₂Bu)₄] ( 2 ), [V(OSiMe^t₂Bu)(lut)] ( 3 ), V(OSiPh₃)₃(THF)₃ ( 4 ), [Li(THF)₄][V(OSiPh₃)₄](THF)₂ ( 5 ), [Li(DME)VMes(OSiMe^t₂Bu)₃] ( 7 ), [Li(THF)₄][VMes · (OSiPh₃)₃] ( 8 ), [Li(THF)₄][VMes₃(OSiMe^t₂Bu)] ( 9 ), and Na[VMes₃(OSiPh₃)](THF)₄ ( 10 ) as well as the vanadium(IV) compounds [V(OSiPh₃)₄] ( 6 ), [VMes₃(OSiMe^t₂Bu)] ( 11 ) and [VMes₃(OSiPh₃)] ( 12 ) are reported. In most cases the vanadium atom displays a coordination number of four. The dimeric structure of 1 with coordination numbers of four and five, respectively, has been deduced from molecular mass measurements, mass spectrometry and its magnetic properties. The crystal structures of compounds 2 , 4 , 5 , 9 and 11 were resolved. Complex 2 resembles a bridged contact ion pair in which both metal centres are in a tetrahedral coordination environment. In 4 the ligands are arranged trigonal bipyramidally with the THF molecules in the axial positions. Complexes 5 and 9 crystallize in separated ion paires with the vanadium in a tetrahedral coordination sphere. The crystal structure of 11 is analogous to that of 9 but with consequences due to the higher oxidation state. Oxidation of the vanadates(III), e. g. 5 , 9 and 10 , yields the corresponding vanadium(IV) compounds 6 , 11 and 12 .     

SYNTHETIC,N.M.R. SPECTROSCOPIC AND X-RAY CRYSTALLOGRAPHIC INVESTIGATIONS ON THE PRODUCTS OF THE REACTIONS OF PHENYL (METHYL) PHOSPHONOTHIOIC DICHLORIDE AND THIOPHOSPHORYL CHLORIDE AND PSCL3 WITH PRIMARY AMINES

Abstract

The syntheses in solution of (i) 2,4-dialkylamino-, (ii) 2,4-dimethyl-, and (iii) 2,4-diphenyl-2,4-dithio-cyclodiphosph(V)azanes, [R′P(S)NR]₂ (R′ = NHR, Ph, or Me; R = alkyl), derived from thiophosphoryl trichloride, methylphosphonothioic and phenylphosphonothioic dichlorides and primary alkylamines are described. N.m.r. spectroscopic properties for these cyclodiphosph(V)azanes and their monomeric precursors, R′P(S)(NHR)₂ (R′ = NHR, Ph, or Me; R = alkyl), are presented and structural inferences are drawn from this data. The X-ray crystal structure of [PhP(S)NBuⁱ]₂ is reported.     

Potential Precursors for Terminal Methylidene Rare-Earth-Metal Complexes Supported by a Superbulky Tris(pyrazolyl)borato Ligand

A series of solvent-free heteroleptic terminal rare-earth-metal alkyl complexes stabilized by a superbulky tris(pyrazolyl)borato ligand with the general formula [Tp^tBu,MeLnMeR] have been synthesized and fully characterized. Treatment of the heterobimetallic mixed methyl/tetramethylaluminate compounds [Tp^tBu,MeLnMe(AlMe₄)] (Ln=Y, Lu) with two equivalents of the mild halogenido transfer reagents SiMe₃X (X=Cl, I) gave [Tp^tBu,MeLnX₂] in high yields. The addition of only one equivalent of SiMe₃Cl to [Tp^tBu,MeLuMe(AlMe₄)] selectively afforded the desired mixed methyl/chloride complex [Tp^tBu,MeLuMeCl]. Further reactivity studies of [Tp^tBu,MeLuMeCl] with LiR or KR (R=CH₂Ph, CH₂SiMe₃) through salt metathesis led to the monomeric mixed-alkyl derivatives [Tp^tBu,MeLuMe(CH₂SiMe₃)] and [Tp^tBu,MeLuMe(CH₂Ph)], respectively, in good yields. The SiMe₄ elimination protocols were also applicable when using SiMe₃X featuring more weakly coordinating moieties (here X=OTf, NTf₂). X-ray structure analyses of this diverse set of new [Tp^tBu,MeLnMeR/X] compounds were performed to reveal any electronic and steric effects of the varying monoanionic ligands R and X, including exact cone-angle calculations of the tridentate tris(pyrazolyl)borato ligand. Deeper insights into the reactivity of these potential precursors for terminal alkylidene rare-earth-metal complexes were gained through NMR spectroscopic studies.     

Chiral Fluorinated α‐Sulfonyl Carbanions: Enantioselective Synthesis and Electrophilic Capture,Racemization Dynamics,and Structure

Enantiomerically pure triflones R¹CH(R²)SO₂CF₃ have been synthesized starting from the corresponding chiral alcohols via thiols and trifluoromethylsulfanes. Key steps of the syntheses of the sulfanes are the photochemical trifluoromethylation of the thiols with CF₃Hal (Hal=halide) or substitution of alkoxyphosphinediamines with CF₃SSCF₃. The deprotonation of RCH(Me)SO₂CF₃ (R=CH₂Ph, iHex) with nBuLi with the formation of salts [RC(Me)? SO₂CF₃]Li and their electrophilic capture both occurred with high enantioselectivities. Displacement of the SO₂CF₃ group of (S)‐MeOCH₂C(Me)(CH₂Ph)SO₂CF₃ (95 % ee) by an ethyl group through the reaction with AlEt₃ gave alkane MeOCH₂C(Me)(CH₂Ph)Et of 96 % ee. Racemization of salts [R¹C(R²)SO₂CF₃]Li follows first‐order kinetics and is mainly an enthalpic process with small negative activation entropy as revealed by polarimetry and dynamic NMR (DNMR) spectroscopy. This is in accordance with a C_α? S bond rotation as the rate‐determining step. Lithium α‐(S)‐trifluoromethyl‐ and α‐(S)‐nonafluorobutylsulfonyl carbanion salts have a much higher racemization barrier than the corresponding α‐(S)‐tert‐butylsulfonyl carbanion salts. Whereas [PhCH₂C(Me)SO₂tBu]Li/DMPU (DMPU = dimethylpropylurea) has a half‐life of racemization at ?105 °C of 2.4 h, that of [PhCH₂C(Me)SO₂CF₃]Li at ?78 °C is 30 d. DNMR spectroscopy of amides (PhCH₂)₂NSO₂CF₃ and (PhCH₂)N(Ph)SO₂CF₃ gave N? S rotational barriers that seem to be distinctly higher than those of nonfluorinated sulfonamides. NMR spectroscopy of [PhCH₂C(Ph)SO₂R]M (M=Li, K, NBu₄; R=CF₃, tBu) shows for both salts a confinement of the negative charge mainly to the C_α atom and a significant benzylic stabilization that is weaker in the trifluoromethylsulfonyl carbanion. According to crystal structure analyses, the carbanions of salts {[PhCH₂C(Ph)SO₂CF₃]Li? L }₂ ( L =2 THF, tetramethylethylenediamine (TMEDA)) and [PhCH₂C(Ph)SO₂CF₃]NBu₄ have the typical chiral C_α? S conformation of α‐sulfonyl carbanions, planar C_α atoms, and short C_α? S bonds. Ab initio calculations of [MeC(Ph)SO₂tBu]^? and [MeC(Ph)SO₂CF₃]^? showed for the fluorinated carbanion stronger n_C→σ* and n_O→σ* interactions and a weaker benzylic stabilization. According to natural bond orbital (NBO) calculations of [R¹C(R²)SO₂R]^? (R=tBu, CF₃) the n_C→σ*_{S? R} interaction is much stronger for R=CF₃. Ab initio calculations gave for [MeC(Ph)SO₂tBu]Li ? 2 Me₂O an O,Li,C_α contact ion pair (CIP) and for [MeC(Ph)SO₂CF₃]Li ? 2 Me₂O an O,Li,O CIP. According to cryoscopy, [PhCH₂C(Ph)SO₂CF₃]Li, [iHexC(Me)SO₂CF₃]Li, and [PhCH₂C(Ph)SO₂CF₃]NBu₄ predominantly form monomers in tetrahydrofuran (THF) at ?108 °C. The NMR spectroscopic data of salts [R¹(R²)SO₂R³]Li (R³=tBu, CF₃) indicate that the dominating monomeric CIPs are devoid of C_α? Li bonds.     

The synthesis,structure, and ethylene polymerization of dimeric salicylaldiminato titanium complexes

A series of dimeric titanium complexes bearing salicylaldiminates, [4-R-6-^tBu-2-(CH=NⁿBu)C₆H₂OTiCl₂(µ-Cl)]₂ [R?=?H (1); R?=?^tBu (2); R?=?NO₂ (3)], have been synthesized in high yield (>90%) by the reaction of corresponding 4-R-6-^tBu-2-(CH=NⁿBu)C₆H₂OSiMe₃ with TiCl₄. The molecular structure of 2 has been confirmed by single-crystal X-ray diffraction analysis. When activated with methylaluminoxane, these complexes exhibit good catalytic activity for ethylene polymerization.     

Phosphaniminato‐Komplexe von Rhenium(VII). Synthesen und Kristallstrukturen von [ReO3(NPR3)] (R = Ph,Et) sowie von [ReO(OSiMe3)3(Me3SiNPEt3)]

Phosphoraneiminato Complexes of Rhenium(VII). Syntheses and Crystal Structures of [ReO₃(NPR₃)] (R = Ph, Et) and of [ReO(OSiMe₃)₃(Me₃SiNPEt₃)] The phosphoraneiminato complexes [ReO₃(NPR₃)] with R = Ph ( 1 ) and R = Et ( 2 ) are made from dirhenium heptaoxide and the silylated phosphoraneimines Me₃SiNPR₃. The complexes 1 and 2 as well as the red silanolate [ReO(OSiMe₃)₃(Me₃SiNPEt₃)] ( 3 ), which is formed as a by‐product in the synthesis of 2 , are characterized crystallographically. 1 and 2 are monomeric molecules, in which the phosphoraneiminato ligands NPR₃^– realize short ReN bonds of 179.3 pm ( 1 ) and 178.6 pm ( 2 ), respectively, with large ReNP bond angles of 162.0° ( 1 ) and 160.6° ( 2 ), respectively. In the rhenium(V) complex 3 the oxoligand occupies the apical position of the tetragonal pyramidal coordination of the rhenium atom, while the oxygen atoms of the Me₃SiO^– groups take the basic positions along with the nitrogen atom of the phosphaneimine molecule.     

Diimido‐, Imido(oxo)‐, Dioxo‐ und Imido(alkyliden)‐Halbsandwich‐Verbindungen über selektive Hydrolyse und α—H‐Abstraktion an Organylkomplexen des sechswertigen Molybdäns und Wolframs

Diimido, Imido Oxo, Dioxo, and Imido Alkylidene Halfsandwich Compounds via Selective Hydrolysis and α—H Abstraction in Molybdenum(VI) and Tungsten(VI) Organyl Complexes Organometal imides [(η⁵‐C₅R₅)M(NR′)₂Ph] (M = Mo, W, R = H, Me, R′ = Mes, tBu) 4 — 8 can be prepared by reaction of halfsandwich complexes [(η⁵‐C₅R₅)M(NR′)₂Cl] with phenyl lithium in good yields. Starting from phenyl complexes 4 — 8 as well as from previously described methyl compounds [(η⁵‐C₅Me₅)M(NtBu)₂Me] (M = Mo, W), reactions with aqueous HCl lead to imido(oxo) methyl and phenyl complexes [(η⁵‐C₅Me₅)M(NtBu)(O)(R)] M = Mo, R = Me ( 9 ), Ph ( 10 ); M = W, R = Ph ( 11 ) and dioxo complexes [(η⁵‐C₅Me₅)M(O)₂(CH₃)] M = Mo ( 12 ), M = W ( 13 ). Hydrolysis of organometal imides with conservation of M‐C σ and π bonds is in fact an attractive synthetic alternative for the synthesis of organometal oxides with respect to known strategies based on the oxidative decarbonylation of low valent alkyl CO and NO complexes. In a similar manner, protolysis of [(η⁵‐C₅H₅)W(NtBu)₂(CH₃)] and [(η⁵‐C₅Me₅)Mo(NtBu)₂(CH₃)] by HCl gas leads to [(η⁵‐C₅H₅)W(NtBu)Cl₂(CH₃)] 14 und [(η⁵‐C₅Me₅)Mo(NtBu)Cl₂(CH₃)] 15 with conservation of the M‐C bonds. The inert character of the relatively non‐polar M‐C σ bonds with respect to protolysis offers a strategy for the synthesis of methyl chloro complexes not accessible by partial methylation of [(η⁵‐C₅R₅)M(NR′)Cl₃] with MeLi. As pure substances only trimethyl compounds [(η⁵‐C₅R₅)M(NtBu)(CH₃)₃] 16 ‐ 18 , M = Mo, W, R = H, Me, are isolated. Imido(benzylidene) complexes [(η⁵‐C₅Me₅)M(NtBu)(CHPh)(CH₂Ph)] M = Mo ( 19 ), W ( 20 ) are generated by alkylation of [(η⁵‐C₅Me₅)M(NtBu)Cl₃] with PhCH₂MgCl via α‐H abstraction. Based on nmr data a trend of decreasing donor capability of the ligands [NtBu]^2— > [O]^2— > [CHR]^2— ? 2 [CH₃]^— > 2 [Cl]^— emerges.     

Homolytic,Heterolytic, Mesolytic ‐ As You Like It: Steering the Cleavage of a HC(sp3)−C(sp3)H Bond in Bis(1H‐2,1‐benzazaborole) Derivatives

A set of (3,3′)‐bis(1‐Ph‐2‐R‐1H‐2,1‐benzazaborole) compounds, in which R=tBu (Bab‐tBu)₂ , R=Dipp (Bab‐Dipp)₂ or R=tBu and Dipp (Bab‐Dipp)(Bab‐tBu) , was synthesized and fully characterized using ¹H, ¹¹B, ¹³C, and ¹⁵N NMR spectroscopy as well as single‐crystal X‐ray diffraction analysis. The central HC(sp³)?C(sp³)H bond with restricted rotation at the junction of both 1H‐2,1‐benzazaborole rings displayed an intriguing reactivity. It was demonstrated that this bond is easily mesolytically cleaved using alkali metals to form the respective aromatic 1Ph‐2R‐1H‐2,1‐benzazaborolyl anions M⁺(THF) _n (Bab‐tBu)^? (M=Li, Na, K) and K⁺(THF) _n (Bab‐Dipp)^? . Furthermore, the central HC(sp³)?C(sp³)H bond of bis(1H‐2,1‐benzazaborole)s is also homolytically cleaved either by heating or photochemical means, giving corresponding 1Ph‐2R‐1H‐2,1‐benzazaborolyl radicals (Bab‐tBu)^. and (Bab‐Dipp)^., which rapidly self‐terminate. Nevertheless, their formation was unambiguously established by NMR analysis of the reaction mixtures containing products of the self‐termination of the radicals after heating or irradiation. (Bab‐Dipp)^. radical was also characterized using EPR spectroscopy. Importantly, it turned out that the essentially non‐polarized HC(sp³)?C(sp³)H bond in (Bab‐tBu)₂ is also cleaved heterolytically with 2 equiv of MeLi, giving the mixture of Li⁺(SOL) _n (Bab‐tBu)^? (SOL=THF or Et₂O) and lithium methyl‐substituted borate complex Li⁺(SOL) _n (Bab‐tBu‐Me)^? in a diastereoselective fashion.     

Die Kristallstruktur von tert-Butylimidomethylindan, [CH3In?NC(CH3)3]4

The X-Ray Structure Determination of tert-Butylimido Methylindane, [CH₃In? NC(CH₃)₃]₄ The reaction of MeInCl₂ with LiN(H)^tBu in a 1 : 2 molar ratio forms [MeIn? N^tBu]₄ in high yield, lithium chloride, and the free amine H₂N^tBu. The crystal structure of the imidomethylindane with a cubic In₄N₄ skeleton has been determined.