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.     

Reactivity of TpMe2‐Supported Yttrium Alkyl Complexes toward Aromatic N‐Heterocycles: Ring‐Opening or CC Bond Formation Directed by CH Activation

Unusual chemical transformations such as three‐component combination and ring‐opening of N‐heterocycles or formation of a carbon–carbon double bond through multiple C–H activation were observed in the reactions of Tp^Me2‐supported yttrium alkyl complexes with aromatic N‐heterocycles. The scorpionate‐anchored yttrium dialkyl complex [Tp^Me2Y(CH₂Ph)₂(THF)] reacted with 1‐methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24‐membered rare‐earth metallomacrocyclic compound [Tp^Me2Y(μ‐N,C‐Im)(η²‐N,C‐Im)]₆ ( 1 ; Im=1‐methylimidazolyl) through two kinds of C–H activations at the C2‐ and C5‐positions of the imidazole ring. However, [Tp^Me2Y(CH₂Ph)₂(THF)] reacted with two equivalents of 1‐methylbenzimidazole to afford a C–C coupling/ring‐opening/C–C coupling product [Tp^Me2Y{η³‐(N,N,N)‐N(CH₃)C₆H₄NHCH?C(Ph)CN(CH₃)C₆H₄NH}] ( 2 ). Further investigations indicated that [Tp^Me2Y(CH₂Ph)₂(THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C–C coupling/ring‐opening product {(Tp^Me2)Y[μ‐η²:η¹‐SC₆H₄N(CH?CHPh)](THF)}₂ ( 3 ). Moreover, the mixed Tp^Me2/Cp yttrium monoalkyl complex [(Tp^Me2)CpYCH₂Ph(THF)] reacted with two equivalents of 1‐methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [Tp^Me2CpY(μ‐N,C‐Im)]₃ ( 5 ), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [Tp^Me2Y(Im‐Tp^Me2)] ( 7 ; Im‐Tp^Me2=1‐methyl‐imidazolyl‐Tp^Me2) and [Cp₃Y(HIm)] ( 8 ; HIm=1‐methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a C?C bond through multiple C–H activations.     

Reaktionen von Fluorphosphoranen mit dem N,O-Bis(trimethylsilyl)-Derivat des o-Aminophenols

Reactions of Fluorophosphoranes with the N,O-Bis(trimethylsilyl) Derivative of o-Aminophenol The reaction of the N,O-bis(trimethylsilyl) derivative of o-aminophenol, 5 , with the tetrafluorophosphoranes, RPF₄, 2a–2d , (R = F, Me, Ph, and 1-adamantyl) in a 1:1 molar ratio led to monocyclic-1,3,2λ⁵-4,5-benzoxazaphospholes, C₆H₄(O)(NH)PF₂R, 6a–6d . ¹⁹F n.m.r. spectroscopic studies suggest a trigonal-bipyramidal structure with the C₆H₄(O)(NH) grouping attached to one axial and one equatorial position at five-coordinate phosphorus for these compounds. The spirophosphoranes, [C₆H₄(O)(NH)]₂PR, 8a – 8d (R = F, Me, Ph, 1-adamantyl) were obtained from the reaction of the appropriate tetrafluorophosphorane, RPF₄, 2a – 2d with 5 in a 1:2 molar ratio. The compounds 8a – 8d also result from a spontaneous scrambling reaction of 6a – 6d , with the corresponding tetrafluorophosphoranes, RPF₄ ( 2a – 2d ) as the other product. Reaction of the difluorophosphorane, Bu₃ⁿPF₂ with 5 and with N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea furnished the cyclic, fluorine-free phosphoranes, 9 and 10 , respectively. The phosphonium bromide, Bu₃ⁿPFBr, reacted with 5 in a 1:1 and a 2:1 molar ratio to produce the ionic compounds, [C₆H₄(OSiMe₃)(NHPBu₃ⁿ)]⁺Br^?, 11 , and [C₆H₄(OPBu₃ⁿ)HNPBu₃ⁿ]²⁺ 2 Br^?, 12 , respectively.     

Reaction of [Os3(CO)10(NCMe)2] with amides and aldehydes; X-ray crystal structure of [Os3(CO)10(μ-H)(COCH2Ph)]

Reaction of [OS₃(CO)₁₀(NCMe)₂] with amides and aldehydes has provided a high-yield route to clusters of the type [OS₃(CO)₁₀H(NHCOR)] (R  H, Me, Ph, Et, Pr) and [OS₃(CO)₁₀H(COR)] (R  Me, Ph, CH₂Ph, C₆H₁₃), respectively; the molecular structure of [OS₃(CO)₁₀H(COCH₂Ph)] has been established by a single-crystal X-ray analysis.     

Bridge Cleavage Reactions of Dinuclear Diselenolenes: Preparation of Palladium Complexes of Novel Chelating Selenolato/Selenide Ligands, [PdX(Se{R′}CnH2n−4Se)(PR3)](n = 6, 7, 8; R = Ph,Bu; X = Br,I; R′ = Me,Et, etc.)

Abstract

The dinuclear palladium diselenolenes [Pd₂(Se₂C_nH_2n?4)₂(PR₃)₂] react with haloalkanes, via electrophilic attack at the bridging selenium atoms, to yield the neutral mononuclear square planar palladium(II) complexes [PdX(Se{R′}C_nH_2n?4Se)(PR₃)] (n = 6, 7, 8; R = Ph, Bu; X = Br, I; R′ = Me, Et, etc.), containing a novel chelating selenolato/selenide ligand, in which the alkylated selenium and halogen donor atoms occupy cis-positions. The products have been characterised by mass spectrometry and multinuclear NMR spectroscopy; the molecular structure of the compound with n = 8, R = Ph, R′ = Et has been determined by X-ray crystallography.     

1‐Azonia‐2‐boratanaphthalenes

The 1‐azonia‐2‐boratanaphthalenes (NH)(BX)C₈H₆ can be synthesized from 2‐aminostyrene and the dihaloboranes XBHal₂ ( 1 ‐ 4 : X = Cl, Br, iPr, tBu). Further derivatives (NH)(BX)C₈H₆ are obtained from 1 by replacing Cl by alkoxy or alkyl groups [ 5 ‐ 8 : X = OMe, OtBu, Me, (CH₂)₃NMe₂]. The hydrolysis of 1 gives a mixture of the bis(azoniaboratanaphthyl) oxide [(NH)BC₈H₆]₂O ( 9 ) and the hydroxy derivative (NH)[B(OH)]C₈H₆ ( 10 ). The diboryl oxide 9 crystallizes in the space group C2/c. The lithiation of 4 at the nitrogen atom gives [NLi(tmen)](BtBu)C₈H₆ ( 11 ), which upon reaction with the diborane(4) B₂Cl₂(NMe₂)₂ yields the 1, 2‐bis(azoniaboratanaphthyl)diborane B₂[N(BtBu)C₈H₆]₂(NMe₂)₂ ( 12 ). The 2‐chloro‐1‐methyl‐4‐phenyl derivative (NMe)(BCl)C₈H₅Ph ( 13 ) of the parent (NH)(BH)C₈H₆ can be synthesized from the aminoborane BCl₂(NMePh) and phenylethyne. Substitution of Cl in 13 gives the derivatives (NMe)(BX)C₈H₅Ph [ 14 ‐ 20 : X = N(SiMe₃)₂, Me, Et, iBu, tBu, CH₂SiMe₃, Ph] and the reaction of 13 with Li₂O affords the bis(azoniaboratanaphthyl) oxide [(NMe)BC₈H₅Ph]₂O ( 21 ). The reaction of 16 or 19 with [(MeCN)₃Cr(CO)₃] yields the complexes [{(NMe)(BX)C₈H₅Ph}Cr(CO)₃] ( 22 , 23 : X = Et, CH₂SiMe₃), in which the chromium atom is hexahapto bound to the homoarene part of 16 or 19 , respectively. The complex 23 crystallizes in the space group P2₁/c. Upon reaction of the phenols para‐C₆H₄R(OH) with the aryldichloroboranes ArBCl₂ and subsequent condensation of the products with phenylethyne, the 1‐oxonia‐2‐boratanaphthalenes O(BAr)C₈H₄RPh with R in position 6 and Ph in position 4 are formed ( 24 ‐ 26 : Ar = Ph, R = H, Me, OMe; 27 ‐ 29 : Ar = C₆F₅, R = H, Me, OMe). The azoniaboratanaphthalenes 1 ‐ 23 were characterized by NMR methods.     

Stepwise synthesis of [Os3(CO)8(R2C2)(R′2C2)] from [Os3(CO)10(R2C2)] under mild conditions,x-ray crystal structure of [Os3(CO)8(Ph2C2)2]; a bis(alkyne) without an osmacyclopentaidiene ring

Treatment of a solution of [Os₃(CO)₁₀(R₂C₂)] (R = Me (1, R = Ph (2)) in CH₂Cl₂ with Me₃No/MeCN in the presence of R′₂C₂ affords the new organometallic cluster [Os₃(CO)₈(R₂C₂)(R′₂C₂)] (R = R′ = Me (3), R = R′ = Ph (4) and R = Ph, R′ = Me (5)). A single crystal X-ray analysis of compound 4 has established a triangular metal framework with both the alkyne units coordinated in a μ₃-η²-6-mode. In toluene, at 80°C, compound 4 undergoes rearrangement to the known compound, [Os₃H(CO)₈(Ph)C₂(C₆H₄))] (6) in which CC bond formation has occurred to produce an osmacyclopentadiene ring.     

The synthesis and spectroscopic properties of some (π-allyl) dicarbonyl-semicarbazonatohalogenomolybdenum(II) complexes

Reaction of [MoX(CO₂(NCMe)₂(η³-C₃H₄R)] in CH₂Cl₂ at room temperature with an equimolar quantity of (R′R″)CNNHCONH₂ gave high yields of the bidentate coordinated semicarbazone complexes [MoX(CO)₂{(R′R″)CNNHCONH₂}(η³-C₃H₄R)] (X = Cl, Br or I; R = H or Me; R′,R″ = H or Me and Me, Et, ⁿPr or Ph) via displacement of two acetonitrile ligands.     

Derivative des borols: VI. Dehydrierende komplexierung von borolenen mit carbonylmetallen: (borol)metall-komplexe von mangan,eisen und cobalt

The reaction of 2-borolenes and 3-borolenes C₄H₆BR (R = Ph, Me, C₆H₁₁, OMe) with Mn, Fe, and Co carbonyls leads to dehydrogenating complexation with formation of simple, i.e. C-unsubstituted (η⁵-borole)metal complexes. Thus, Mn₂(CO)₁₀ gives the triple-decked complexes (μ-η⁵-C₄H₄BR)[Mn(CO)₃]₂ (R = Ph, OMe). By irradiation of Fe(CO)₅ the half-sandwich complexes Fe(CO)₃ (η⁵-C₄H₄BR) (R = Ph, Me, C₆H₁₁, OMe) are formed, whereas Co₂(CO)₈ yields the dinuclear complexes (μ-CO)₂[Co(CO)(η⁵-C₄H₄BR)]₂ (Co-Co) (R = Ph, Me). A low-temperature X-ray structure determination of Fe(CO)₃(η⁵-C₄H₄BPh) is described in detail.     

Nucleophilic addition of bifunctional sulfimidosulfides to platinum(<Emphasis Type="SmallCaps">IV</Emphasis>)-coordinated nitriles

Reactions of the platinum(IV) nitrile complexes [PtCl₄(RCN)₂] (R = Me, CH₂Ph, Ph) with 1,2- and 1,4-PhS(=NH)C₆H₄SPh in CH₂Cl₂ afforded addition products of sulfimides and coordinated nitriles, viz., the [PtCl₄{NH=C(R)N=S(Ph)(C₆H₄SPh)}₂] complexes. The latter were isolated in 75—90% yields and characterized by elemental analysis, positive-ion FAB mass spectrometry, IR spectroscopy, and ¹H and ¹³C¹H NMR spectroscopy. The temperature dependence of the ¹H NMR spectra of the model [PtCl₄{NH=C(R)N=SPh₂}₂] complexes (R = Me, Et) in CD₂Cl₂ studied in a temperature range from +40 to -70 °C demonstrated that E—Z isomerization of the ligands is a dynamic process in a range from +40 to -10 °C. The activation free energy of this process was calculated.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1618–1622, August, 2004.     

Synthese und Struktur der Komplexe [(Me2PhP)3Cl2Re≡N‐RuCl2(C6H6)] und [(Me2PhP)3Cl2Re≡N‐RhCl(COD)]

Synthesis and Crystal Structure of the Complexes [(Me₂PhP)₃Cl₂Re≡N‐RuCl₂(C₆H₆)] and [(Me₂PhP)₃Cl₂Re≡N‐RhCl(COD)] The heteronuclear complex [(Me₂PhP)₃Cl₂Re≡N‐RuCl₂(C₆H₆)] ( 1 ) is obtained by the reaction of [ReNCl₂(PMe₂Ph)₃] with [RuCl₂(C₆H₆)]₂ in C₆H₅CN in form of red crystals with the composition 1 ·C₆H₅CN crystallizing in the monoclinic space group P2₁/c with a =1149.77(8), b = 3085.9(3), c = 1172.1(1) pm, β = 104.766(9)° and Z = 4. In the dinuclear complex the complex fragment [RuCl₂(C₆H₆)] is connected by an asymmetric nitrido bridge with the nitrido complex [ReNCl₂(PMe₂Ph)₃]. The nitrido bridge is characterised by a bond angle Re‐N‐Ru of 170.6(3)° and distances Re‐N = 170.2(5) and Ru‐N = 199.0(5) pm. The reaction of [ReNCl₂(PMe₂Ph)₃] with [RhCl(COD)]₂ in benzonitrile yields orange crystals of [(Me₂PhP)₃Cl₂Re≡N‐RhCl(COD)] ( 2 ) with the space group P2₁/c and a = 1522.3(2), b = 1274.85(4), c = 1921.2(2) pm, β = 106.759(7)° and Z = 4. The monovalent Rh atom exhibits a square planar coordination with the two π‐bonds of the cycloocta‐1, 5‐diene occupying cis positions. The distances in the almost linear nitrido bridge (Re‐N‐Rh = 174.8(4)°>) are Re‐N = 172.2(6) pm and Rh‐N = 195.6(6) pm.     

Hoop‐Shaped Condensed Aromatic Systems: Synthesis and Structure of Iron– and Ruthenium–Hepta(organo)[60]fullerene Complexes

Potassium reduction of iron– and ruthenium–penta(organo)[60]fullerene complexes, [M(η⁵‐C₆₀R₅)(η⁵‐Cp)] ( 1 a : M=Fe, R=Ph; 1 b : M=Fe, R=Me; 1 c : M=Ru, R=Ph; 1 d : M=Ru, R=Me; Cp=C₅H₅) gave mono‐ and dianions of these complexes. Treatment of the dianion 1 a with α‐bromodiphenylmethane gave three different iron–hepta(organo)[60]fullerenes, [Fe{η⁵‐C₆₀Ph₅(CHPh₂)₂}(η⁵‐Cp)], as a mixture of regioisomers. All three compounds were fully characterized by physical methods, including X‐ray crystallography and electrochemical measurements. One of the three compounds contains a new hoop‐shaped condensed aromatic system.     

Amidinato and triazenido complexes of ruthenium(II): X-ray crystal structure of the N,N′-diphenylformamidine fragmentation product [RuCl(NH2Ph){PhNC(H)NPh}(Me2SO)2]

N,N′-Diphenylamidines, PhNC(R)NHPh (R=H, Me, Et, Ph), and 1,3-diaryltriazenes, ArNNNHAr (Ar=p-C₆H₄X, X=H, Cl, Me, OMe) react with ruthenium(II) complexes, [RuCl₂(C₇H₈)]_n, [RuCl₂(CO)₂]_n and [RuCl₂(Me₂SO)₄] in the presence of a base (NEt₃ or Na₂CO₃) to afford a selection of bis(chelate) products [Ru{PhNC(R)NPh}₂L₂] and [Ru(ArNNNAr)₂L₂] (L=CO, Me₂SO; L₂=C₇H₈). In contrast one particular combination — [RuCl₂(Me₂SO)₄]/PhNC(H)NHPh/NEt₃ — in refluxing dimethylformamide yields a novel amidine fragmentation product [RuCl(NH₂Ph){PhNC(H)NPh}(Me₂SO)₂] which has been characterised by X-ray diffraction methods.     

Organometallic Molybdenum(V) Complexes with Primary Phosphine Ligands. Syntheses,Spectroscopic Properties and Molecular Structures of [Cp°MoCl4(PH2R)] (R = But, 1‐Ad,Cy, Ph, 2, 4, 6‐Me3C6H2, 2, 4, 6‐Pri3C6H2, Cp° = C5EtMe4)

[Cp°MoCl₄] (Cp° = C₅EtMe₄) reacts with primary phosphines PH₂R to give the paramagnetic phosphine complexes [Cp°MoCl₄(PH₂R)] [Cp° = C₅EtMe₄, R = Bu^t ( 1 ), 1‐Ad (1‐Ad = 1‐adamantyl; 2 ), Cy ( 3 ), Ph ( 4 ), Mes (Mes = 2, 4, 6‐Me₃C₆H₂; 5 ), Tipp (Tipp = 2, 4, 6‐Prⁱ₃C₆H₂; 6 )]. 1 — 6 were characterized spectroscopically (IR, MS), and X‐ray crystal structures were determined for 1 — 4 and 6 . EPR investigations in liquid and frozen solution confirmed the presence of Mo^V species, and the data were used to analyze the spin‐density distribution in the first coordination sphere. Complexes 3 and 4 react with two equivalents of NEt₃ with formation of [Cp°MoCl₂(η³‐P₄Cy₄H)] ( 7 ) and [Cp°₂Mo₂(μ‐Cl)₂(μ‐P₄Ph₄)] ( 8 ), respectively, in low yield. Complexes 7 and 8 were characterized by X‐ray crystallography.     

Bridged bimetallic complexes of molybdenum tris(dimethylpyrazolyl)borates

Summary The syntheses of [MoL^*(NO)(OR)NHC₆H₄NH₂)], [MoL^*(NO)I(NHC₆H₄NHMoL^*(NO)(OR)] (L^*=tris(3,5-dimethylpyrazolyl)borate; R=Me, Et,n-Pr,i-Pr,n-Bu and C₅H₁₁), and [{MoL^*(NO)(OR)}₂NHC₆H₄NH] (R=Me, Et andn-Pr) are described, the compounds being characterised by elemental analyses, i.r. and¹H n.m.r. spectroscopy.     

Molybdenum alkyl- and aryl-thiolates

The reaction between [(η⁵-C₅H₅)MoH(CO)₃] and disulphides gives dimeric or trimeric complexes depending upon the conditions. The syntheses of the novel trinuclear molybdenum carbonyl complex [{Mo(η⁵-C₅H₅)(SR)(μ-CO)(CO)}₃] (R = Me), and dinuclear compounds [Mo₂(η⁵-C₅H₅)(μ-SR)₃(CO)₄] (R = Me) and [Mo₂(η⁵-C₅H₅)₂(SR)₂(CO)₂(μ-SR)(μ-Br)] (R = Me or Ph) are reported.     

Synthesis and characterization of modular polyphosphonate homopolymers and copolymers

Linear polyphosphonates with the generic formula –[P(Ph)(X)OR′O]_n– (X = S or Se) have been synthesized by polycondensations of P(Ph)(NEt₂)₂ and a diol (HOR′OH = 1,4-cyclohexanedimethanol, 1,4-benzenedimethanol, tetraethylene glycol, or 1,12-dodecanediol) followed by reaction with a chalcogen. Random copolymers have been synthesized by polycondensations of P(Ph)(NEt₂)₂ and mixture of two of the diols in a 2:1:1 mol ratio followed by reaction with a chalcogen. Block copolymers with the generic formula –[P(Ph)(X)OR′O]_{(x + 2)} –[P(Ph)(X)OR′O]_{(x + 3)}– (X = S or Se) have been synthesized by the polycondensations of Et₂N[P(Ph)(X)OR′O]_{(x + 2)}P(Ph)NEt₂ oligomers with HOR′O[P(Ph)(X)OR′O]_{(x + 3)}H oligomers followed by reaction with a chalcogen. The Et₂N[P(Ph)(X)OR′O]_{(x + 2)}P(Ph)NEt₂ oligomers are prepared by the reaction of an excess of P(Ph)(NEt₂)₂ with a diol while the HOR′O[P(Ph)(X)OR′O]_{(x + 3)}H oligomers are prepared by the reaction of P(Ph)(NEt₂)₂ with an excess of the diol. In each case the excess, x is the same and determines the average block sizes. All of the polymers were characterized using ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy, TGA, DSC, and SEC. ³¹P{¹H} NMR spectroscopy demonstrates that the random and block copolymers have the expected arrangements of monomers and, in the case of block copolymers, verifies the block sizes. All polymers are thermally stable up to ~300°C, and the arrangements of monomers in the copolymers (block vs. random) affect their degradation temperatures and T_g profiles. The polymers have weight average MWs of up to 3.8 × 10⁴ Da.     

Synthetic studies of the reaction between aldehydes and the triosmium cluster [Os3(CO)10(NCMe)2]

The reaction of [Os₃(CO)₁₀(NCMe)₂] (1) with aldehydes in refluxing cyclohexane affords the metal clusters [Os₃(CO)₁₀(μ-H)(COR)] (2, R = Me, Ph, CH₂Ph or C₆H₁₃) in ca. 50% yield. The compound 2 (R = CH₂Ph) undergoes hydrogenation under pressure to give the corresponding alcohol, while decarbonylation occurs in the presence of Me₃NO to give the Me₃N-substituted derivative [Os₃(CO)₉(NMe₃)(μ-H)(COCH₂Ph)] in 90% yield.     

Syntheses and Reactions of Dimolybdenum Alkyne Compounds Containing Functionally Substituted Ligands. The Crystal Structure of [Co2Mo2(μ4-CHCH)(μ-CO)4(CO)4-(η5-C5H4C(O)Me)2]

Abstract

Three dimolybdenum alkyne complexes containing functionally substituted ligands [Mo₂(μ-CHCH)(CO)₄(η⁵?C₅H₄C(O)R)₂] [R ? OEt, (1a); R ? Me, (1b); R ? Ph, (1c)] were synthesized by reactions of acetylene with in situ generated metal-metal triply bonded complexes [Mo(CO)₂(η⁵?C₅H₄C(O)R)]₂ (R ? OEt, Me, Ph). Further reaction of (1a), (1b) or (1c) with Co₂(CO)₈ in refluxing toluene gave another three new butterfly compounds [Co₂Mo₂-(μ₄-CHCH)(μ-CO)₄(CO)₄(η⁵-C₅H₄C(O)R)₂] [R ? OEt, (2a); R ? Me, (2b); R ? Ph, (2c)]. The resulting compounds were characterized by elemental analyses, IR, ¹H NMR and MS. The crystal structure of (2b) was determined by single-crystal X-ray analysis. The results indicate that the existence of functional groups on the cyclopentadienyl ring has an influence on the reactivity of this type of complex.     

Stabilization of a Silaaldehyde by its η2 Coordination to Tungsten

Treatment of pyridine‐stabilized silylene complexes [(η⁵‐C₅Me₄R)(CO)₂(H)W?SiH(py)(Tsi)] (R=Me, Et; py=pyridine; Tsi=C(SiMe₃)₃) with an N‐heterocyclic carbene ^MeIⁱPr (1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) caused deprotonation to afford anionic silylene complexes [(η⁵‐C₅Me₄R)(CO)₂W?SiH(Tsi)][H^MeIⁱPr] (R=Me ( 1‐Me ); R=Et ( 1‐Et )). Subsequent oxidation of 1‐Me and 1‐Et with pyridine‐N‐oxide (1 equiv) gave anionic η²‐silaaldehydetungsten complexes [(η⁵‐C₅Me₄R)(CO)₂W{η²‐O?SiH(Tsi)}][H^MeIⁱPr] (R=Me ( 2‐Me ); R=Et ( 2‐Et )). The formation of an unprecedented W‐Si‐O three‐membered ring was confirmed by X‐ray crystal structure analysis.