Reactivity of Yttrium Carboxylates Toward Alkylaluminum Hydrides

Yttrocene‐carboxylate complex [Cp*₂Y(OOCAr^Me)] (Cp*=C₅Me₅, Ar^Me=C₆H₂Me₃‐2,4,6) was synthesized as a spectroscopically versatile model system for investigating the reactivity of alkylaluminum hydrides towards rare‐earth‐metal carboxylates. Equimolar reactions with bis‐neosilylaluminum hydride and dimethylaluminum hydride gave adduct complexes of the general formula [Cp*₂Y(μ‐OOCAr^Me)(μ‐H)AlR₂] (R=CH₂SiMe₃, Me). The use of an excess of the respective aluminum hydride led to the formation of product mixtures, from which the yttrium‐aluminum‐hydride complex [{Cp*₂Y(μ‐H)AlMe₂(μ‐H)AlMe₂(μ‐CH₃)}₂] could be isolated, which features a 12‐membered‐ring structure. The adduct complexes [Cp*₂Y(μ‐OOCAr^Me)(μ‐H)AlR₂] display identical ¹J(Y,H) coupling constants of 24.5 Hz for the bridging hydrido ligands and similar ⁸⁹Y NMR shifts of δ=?88.1 ppm (R=CH₂SiMe₃) and δ=?86.3 ppm (R=Me) in the ⁸⁹Y DEPT45 NMR experiments.     

Nitro‐substituted iron(II) tridentate bis(imino)pyridine complexes as high‐temperature catalysts for the production of α‐olefins

A new series of nitro‐substituted bis(imino)pyridine ligands {2,6‐bis[1‐(2‐methyl‐4‐nitrophenylimino)ethyl]pyridine, 2,6‐bis[1‐(4‐nitrophenylimino)ethyl]pyridine, (1‐{6‐[1‐(4‐nitro‐phenylimino)‐ethyl]‐pyridin‐2‐yl}‐ethylidene)‐(2,4,6‐trimethyl‐phenyl)‐amine, and 2,6‐bis[1‐(2‐methyl‐3‐nitrophenylimino)ethyl]pyridine} and their corresponding Fe(II) complexes [{p‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐ Me? p‐NO₂}FeCl₂ ( 10 ), L₂FeCl₂ ( 11 ), {m‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? m‐NO₂}FeCl₂ ( 12 ), and {p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Mes}FeCl₂ ( 14 )] were synthesized. According to X‐ray analysis, there were shortenings of the axial Fe? N bond lengths (up to 0.014 Å) in para‐nitro‐substituted complex 10 and (up to 0.015 Å) in meta‐nitro‐substituted complex 12 versus the Fe(II) complex without nitro groups [{o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me}FeCl₂ ( 1 )]. Complexes 10 , 12 , and 14 afforded very active catalysts for the production of α‐olefins and were more temperature‐stable and had longer lifetimes than parent non‐nitro‐substituted Fe(II) complex 1 . The reaction between FeCl₂ and a sterically less hindered ligand [p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Ph? p‐NO₂] resulted in the formation of octahedral complex 11 . A para‐dialkylamino‐substituted bis(imino)pyridine ligand [p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂] and the corresponding Fe(II) complex [{p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂}FeCl₂ ( 16 )] were synthesized to evaluate the effect of enhanced electron donation of the ligand on the catalytic performance. According to X‐ray analysis, there was a shortening (up to 0.043 Å) of the axial Fe? N bond lengths in para‐diethylamino‐substituted complex 16 in comparison with parent Fe(II) complex 1 . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2615–2635, 2006     

Formation and Reactivity of an Aluminabenzene Ligand at Pentadienyl‐Supported Rare‐Earth Metals

The half‐open rare‐earth‐metal aluminabenzene complexes [(1‐Me‐3,5‐tBu₂‐C₅H₃Al)(μ‐Me)Ln(2,4‐dtbp)] (Ln=Y, Lu) are accessible via a salt metathesis reaction employing Ln(AlMe₄)₃ and K(2,4‐dtbp). Treatment of the yttrium complex with B(C₆F₅)₃ and tBuCCH gives access to the pentafluorophenylalane complex [{1‐(C₆F₅)‐3,5‐tBu₂‐C₅H₃Al}{μ‐C₆F₅}Y{2,4‐dtbp}] and the mixed vinyl acetylide complex [(2,4‐dtbp)Y(μ‐η¹:η³‐2,4‐tBu₂‐C₅H₄)(μ‐CCtBu)AlMe₂], respectively.     

Zur Reaktivität von Titanocenkomplexen [Ti(Cp′)2(η2‐Me3SiC≡CSiMe3)] (Cp′ = Cp,Cp*) gegenüber Benzoldicarbonsäuren

On the Reactivity of Titanocene Complexes [Ti(Cp′)₂(η²‐Me₃SiC≡CSiMe₃)] (Cp′ = Cp, Cp*) towards Benzenedicarboxylic Acids Titanocene complexes [Ti(Cp′)₂(BTMSA)] ( 1a , Cp′ = Cp = η⁵‐C₅H₅; 1b , Cp′ = Cp* = η⁵‐C₅Me₅; BTMSA = Me₃SiC≡CSiMe₃) were found to react with iodine and methyl iodide yielding [Ti(Cp′)₂(μ‐I)₂] ( 2a / b ; a refers to Cp′ = Cp and b to Cp′ = Cp*), [Ti(Cp′)₂I₂] ( 3a / b ) and [Ti(Cp′)₂(Me)I] ( 4a / b ), respectively. In contrast to 2a , complex 2b proved to be highly moisture sensitive yielding with cleavage of HCp* [{Ti(Cp*)I}₂(μ‐O)] ( 7 ). The corresponding reactions of 1a / b with p‐cresol and thiophenol resulted in the formation of [Ti(Cp′)₂{O(p‐Tol)}₂] ( 5a / b ) and [Ti(Cp′)₂(SPh)₂] ( 6a / b ), respectively. Reactions of 1a and 1b with 1,n‐benzenedicarboxylic acids (n = 2–4) resulted in the formation of dinuclear titanium(III) complexes of the type [{Ti(Cp′)₂}₂{μ‐1,n‐(O₂C)₂C₆H₄}] (n = 2, 8a / b ; n = 3, 9a / b ; n = 4, 10a / b ). All complexes were fully characterized analytically and spectroscopically. Furthermore, complexes 7 , 8b , 9a ·THF, 10a / b were also be characterized by single‐crystal X‐ray diffraction analyses.     

Stepwise Strategy to Cyclometallated PtII Complexes with N‐Heterocyclic Carbene Ligands: A Luminescence Study on New β‐Diketonate Complexes

The imidazolium salt 3‐methyl‐1‐(naphthalen‐2‐yl)‐1H‐imidazolium iodide ( 2 ) has been treated with silver(I) oxide and [{Pt(μ‐Cl)(η³‐2‐Me‐C₃H₄)}₂] (η³‐2‐Me‐C₃H₄=η³‐2‐methylallyl) to give the intermediate N‐heterocyclic carbene complex [PtCl(η³‐2‐Me‐C₃H₄)(H$\widehat{CC}$ *‐κC*)] ( 3 ) (H$\widehat{CC}$ *‐κC*=3‐methyl‐1‐(naphthalen‐2‐yl)‐1H‐imidazol‐2‐ylidene). Compound 3 undergoes regiospecific cyclometallation at the naphthyl ring of the NHC ligand to give the five‐membered platinacycle compound [{Pt(μ‐Cl)($\widehat{CC}$ *)}₂] ( 4 ). Chlorine abstraction from 4 with β‐diketonate Tl derivatives rendered the corresponding neutral compounds [Pt($\widehat{CC}$ *)(L‐O,O′)] {L=acac (HL=acetylacetone) 5 , phacac (HL=1,3‐diphenyl‐1,3‐propanedione) 6 , hfacac (HL=hexafluoroacetylacetone) 7 }. All of the compounds ( 3 – 7 ) were fully characterized by standard spectroscopic and analytical methods. X‐ray diffraction studies were performed on 5 – 7 , revealing short Pt?Pt and π–π interactions in the solid‐state structure. The influence of the R‐substituents of the β‐diketonate ligand on the photophysical properties and the use of the most efficient emitter, 5 , as phosphor converter has also been studied.     

Synthese und Charakterisierung neuer intramolekular stickstoffstabilisierter Organoaluminium‐ und Organogalliumalkoxide

Synthesis and Characterization of New Intramolecularly Nitrogen‐stabilized Organoaluminium‐ and Organogallium Alkoxides The intramolecularly nitrogen stabilized organoaluminium alkoxides [Me₂Al{μ‐O(CH₂)₃NMe₂}]₂ ( 1a ), Me₂AlOC₆H₂(CH₂NMe₂)₃‐2,4,6 ( 2a ), [(S)‐Me₂Al{μ‐OCH₂CH(i‐Pr)NH‐i‐Pr}]₂ ( 3a ) and [(S)‐Me₂Al{μ‐OCH₂CH(i‐Pr)NHCH₂Ph}]₂ ( 4 ) are formed by reacting equimolar amounts of AlMe₃ and Me₂N(CH₂)₃OH, C₆H₂[(CH₂NMe₂)₃‐2,4,6]OH, (S)‐i‐PrNHCH(i‐Pr)CH₂OH, or (S)‐PhCH₂NHCH(i‐Pr)CH₂OH, respectively. An excess of AlMe₃ reacts with Me₂N(CH₂)₂OH, Me₂N(CH₂)₃OH, C₆H₂[(CH₂NMe₂)₃‐2,4,6]OH, and (S)‐i‐PrNHCH(i‐Pr)CH₂OH producing the “pick‐a‐back” complexes [Me₂AlO(CH₂)₂NMe₂](AlMe₃) ( 5 ), [Me₂AlO(CH₂)₃NMe₂](AlMe₃) ( 1b ), [Me₂AlOC₆H₂(CH₂NMe₂)₃‐2,4,6](AlMe₃)₂ ( 2b ), and [(S)‐Me₂AlOCH₂CH(i‐Pr)NH‐i‐Pr](AlMe₃) ( 3b ), respectively. The mixed alkyl‐ or alkenylchloroaluminium alkoxides [Me(Cl)Al{μ‐O(CH₂)₂NMe₂}]₂ ( 6 ) and [{CH₂=C(CH₃)}(Cl)Al{μ‐O(CH₂)₂NMe₂}]₂ ( 8 ) are to obtain from Me₂AlCl and Me₂N(CH₂)₂OH and from [Cl₂Al{μ‐O(CH₂)₂NMe₂}]₂ ( 7 ) and CH₂=C(CH₃)MgBr, respectively. The analogous dimethylgallium alkoxides [Me₂Ga{μ‐O(CH₂)₃NMe₂}]₂ ( 9 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)NH‐i‐Pr}]_n ( 10 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)NHCH₂Ph}]_n ( 11 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)N(Me)CH₂Ph}]_n ( 12 ) and [(S)‐Me₂Ga{μ‐OCH₂(C₄H₇NHCH₂Ph)}]_n ( 13 ) result from the equimolar reactions of GaMe₃ with the corresponding alcohols. The new compounds were characterized by elemental analyses, ¹H‐, ¹³C‐ and ²⁷Al‐NMR spectroscopy, and mass spectrometry. Additionally, the structures of 1a , 1b , 2a , 2b , 3a , 5 , 6 and 8 were determined by single crystal X‐ray diffraction.     

Synthesis,Structural Characterization and Luminescence Studies of Di‐ and Trinuclear Gold(I) Alkynyl‐phosphine Complexes

Reactions of the polymer {Au^IC₂Ph}_n with polyphosphine ligands [1,4‐bis(2‐diphenylphosphino‐1H‐imidazol‐1‐yl)‐benzene (dpib), 1,3,5‐tris(4‐diphenylphosphinophenyl)benzene (tppb), 2,2′‐bis(diphenylphosphanyl)‐4,4′‐bipyridine (dpbp), and 3,6‐bis(diphenylphosphanyl)pyridazine (dppz)] afforded four gold(I) alkynyl‐polyphosphine complexes [{AuC₂Ph}₂(μ‐dpib)] ( 1 ), [{AuC₂Ph}₃(μ₃‐tppb)] ( 2 ), [{AuC₂Ph}₂(μ‐dpbp)] ( 3 ), and [{AuC₂Ph}₂(μ‐dppz)] ( 4 ) in nearly quantitative yield. The compounds obtained were characterized using elemental analysis, ESI‐MS, X‐ray crystallography, and polynuclear NMR spectroscopy. Intermolecular aurophilic interaction together with π–π and σ–π stacking build up the supramolecular 3D network of complex 3 , whereas none of these intermolecular bondings were found in the crystal structures of compounds 1 , 2 , and 4 . Complexes 1 – 4 are luminescent both in solution (CH₂Cl₂) and in solid state under laser irradiation (λ_ex = 308 nm). In solution, the diphosphine complexes 1 – 4 display dual emission corresponding to ligand centered transitions (λ_em = 360–375 nm) along with weaker contribution from MLCT excited states at ca. 490 nm. The long wavelength component of the emission plays a dominant role in the solid state luminescence spectra of complexes 1 , 3 , and 4 (460, 544, 520 nm, respectively) whereas the triphosphine complex 2 shows dual luminescence (372 and 520 nm) with considerable contribution from ligand centered excited state.     

Solution Structure and Reactivity with Metallocenes of AlMe2F: Mimicking Cation–Anion Interactions in Metallocenium–Methylalumoxane Inner‐Sphere Ion Pairs

The solution structure of AlMe₂F and its reactivity with a prototypical ansa‐metallocene have been investigated by advanced NMR techniques, in an attempt to indirectly shed some light on the structure and working principles of methylalumoxane (MAO) mixtures in olefin polymerization. In solution, AlMe₂F gives rise to a complex equilibrium of oligomeric species, including a heterocubane [(Me₂Al)₄F₄] tetramer, resembling the behavior of MAO. This complex mixture reacts with (ETH)ZrMe₂ (ETH=rac ‐[ethylenebis(4,5,6,7‐tetrahydro‐1‐indenyl)]) to afford [(ETH)ZrMe^δ+(μ‐F)(AlMe₂F)_nAlMe₃^δ−] inner‐sphere ion pairs through successive insertions/deinsertions of AlMe₂F units into the Zr⋅⋅⋅(μ‐F) bond.     

Molekül‐ und Kristallstruktur von Bis[chloro(μ‐phenylimido)(η5‐pentamethylcyclopentadienyl)tantal(IV)](Ta–Ta), [{TaCl(μ‐NPh)Cp*}2]

Molecular and Crystal Structure of Bis[chloro(μ‐phenylimido)(η⁵‐pentamethylcyclopentadienyl)tantalum(IV)](Ta–Ta), [{TaCl(μ‐NPh)Cp*}₂] Despite the steric hindrance of the central atom in [TaCl₂(NPh)Cp*] (Ph = C₆H₅, Cp* = η⁵‐C₅(CH₃)₅), caused by the Cp* ligand, the imido‐ligand takes a change in bond structure when this educt is reduced to the binuclear complex [{TaCl(μ‐NPh)Cp*}₂] in which tantalum is stabilized in the unusual oxidation state +4.     

Heterometallic Polyhydride Complexes Containing Yttrium Hydrides with Different Cp Ligands: Synthesis,Structure, and Hydrogen‐Uptake/Release Properties

A new family of Y₄/M₂ and Y₅/M heterobimetallic rare‐earth‐metal/d‐block‐transition‐metal? polyhydride complexes has been synthesized. The reactions of the tetranuclear yttrium? octahydride complex [{Cp′′Y(μ‐H)₂}₄(thf)₄] (Cp′′=C₅Me₄H, 1‐C₅Me₄H ) with one equivalent of Group‐6‐metal? pentahydride complexes [Cp*M(PMe₃)H₅] (M=Mo, W; Cp*=C₅Me₅) afforded pentanuclear heterobimetallic Y₄/M? polyhydride complexes [{(Cp′′Y)₄(μ‐H)₇}(μ‐H)₄MCp*(PMe₃)] (M=Mo ( 2 a ), W ( 2 b )). UV irradiation of compounds 2 a , b in THF gave PMe₃‐free complexes [{(Cp′′Y)₄(μ‐H)₆(thf)₂}(μ‐H)₅MCp*] (M=Mo ( 3 a ), W ( 3 b )). Compounds 3 a , b reacted with one equivalent of [Cp*M(PMe₃)H₅] to afford hexanuclear Y₄/M₂ complexes [{Cp*M(μ‐H)₅}{(Cp′′Y)₄(μ‐H)₅}{(μ‐H)₄MCp*(PMe₃)}] (M=Mo ( 4 a ), W ( 4 b )). UV irradiation of compounds 4 a , b provided the PMe₃‐free complexes [(Cp′′Y)₄(μ‐H)₄{(μ‐H)₅MCp*}₂] (M=Mo ( 5 a ), W ( 5 b )). C₅Me₄Et‐ligated analogue [(Cp′′Y)₄(μ‐H)₄{(μ‐H)₅Mo(C₅Me₄Et)}₂] ( 5 a′ ) was obtained from the reaction of 1‐C₅Me₄H with [(C₅Me₄Et)Mo(PMe₃)H₅]. On the other hand, the reaction of pentanuclear yttrium? decahydride complex [{(C₅Me₄R)Y(μ‐H)₂}₅(thf)₂] ( 1‐C₅Me₅ : R=Me; 1‐C₅Me₄Et : R=Et) with [Cp*M(PMe₃)H₅] gave the hexanuclear heterobimetallic Y₅/M? polyhydride complexes [({(C₅Me₄R)Y}₅(μ‐H)₈)(μ‐H)₅MCp*] ( 6 a : M=Mo, R=Me; 6 a′ : M=Mo, R=Et; 6 b : M=W, R=Me). Compound 5 a released two molecules of H₂ under vacuum to give [(Cp′′Y)₄(μ‐H)₂{(μ‐H)₄MoCp*}₂] ( 7 ). In contrast, compound 6 a lost one molecule of H₂ under vacuum to yield [{(Cp*Y)₅(μ‐H)₇}(μ‐H)₄MoCp*] ( 8 ). Both compounds 7 and 8 readily reacted with H₂ to regenerate compounds 5 a and 6 a , respectively. The structures of compounds 4 a , 5 a′ , 6 a′ , 7 , and 8 were determined by single‐crystal X‐ray diffraction.     

[{Cp*(OC)2Re}2(μ‐POH)], ein Zweikernkomplex mit einem verbrückenden Hydroxiphosphiniden‐Liganden

[{Cp*(OC)₂Re}₂(μ‐POH)], a Dinuclear Complex with a Bridging Hydroxiphosphinidene Ligand The reaction of [{Cp*(OC)₂Re}₄(μ₄‐η¹ : η¹ : η¹ : η¹‐P₂)] ( 1 ) with 0.1 m HCl gives [{Cp*(OC)₂Re}₂(μ‐POH)] ( 2 ), the X‐ray crystal structure of which reveals a dinuclear rhenium complex with a μ‐POH (hydroxiphosphinidene) ligand.     

Syntheses and Characterization of New Vinyl‐Borylene Complexes by the Hydroboration of Alkynes with [(μ3‐BH)(Cp*RuCO)2(μ‐CO)Fe(CO)3]

Room temperature photolysis of a triply‐bridged borylene complex, [(μ₃‐BH)(Cp*RuCO)₂(μ‐CO)Fe(CO)₃] ( 1 a ; Cp*=C₅Me₅), in the presence of a series of alkynes, 1,2‐diphenylethyne, 1‐phenyl‐1‐propyne, and 2‐butyne led to the isolation of unprecedented vinyl‐borylene complexes (Z)‐[(Cp*RuCO)₂(μ‐CO)B(CR)(CHR′)] ( 2 : R, R′=Ph; 3 : R=Me, R′=Ph; 4 : R, R′=Me). This reaction permits a hydroboration of alkyne through an anti ‐ Markovnikov addition. In stark contrast, in the presence of phenylacetylene, a metallacarborane, closo‐[1,2‐(Cp*Ru)₂(μ‐CO)₂{Fe₂(CO)₅}‐4‐Ph‐4,5‐C₂BH₂] ( 5 a) , is formed. A plausible mechanism has been proposed for the formation of vinyl‐borylene complexes, which is supported by density functional theory (DFT) methods. Furthermore, the calculated ¹¹B NMR chemical shifts accurately reflect the experimentally measured shifts. All the new compounds have been characterized in solution by mass spectrometry and IR, ¹H, ¹¹B, and ¹³C NMR spectroscopies and the structural types were unequivocally established by crystallographic analysis of 2 , 5 a , and 5 b .     

Synthese und Molekülstruktur von [{Cp′(μ‐η1 : η5‐C5H3Me)Mo(μ‐AlRH)}2] (Cp′ = C5H4Me,R = iBu,Et)

Synthesis and Molecular Structure of [{Cp′(μ‐η¹ : η⁵‐C₅H₃Me)Mo(μ‐AlRH)}₂] (Cp′ = C₅H₄Me, R = ⁱBu, Et) [Cp′₂MoH₂] reacts with HAlR₂ to give [{Cp′(μ‐η¹ : η⁵‐C₅H₃Me)Mo(μ‐AlRH)}₂] (Cp′ = C₅H₄Me, R = ⁱBu ( 1 ), Et ( 2 )). Crystal structure determinations were carried out on [Cp′₂MoH₂] and 1 . 1 exhibits a direct Mo–Al bond (2.636(2) Å).     

Structurally Defined Potassium‐Mediated Zincation of Pyridine and 4‐R‐Substituted Pyridines (R=Et,iPr, tBu,Ph, and Me2N) by Using Dialkyl–TMP–Zincate Bases

Two potassium–dialkyl–TMP–zincate bases [(pmdeta)K(μ‐Et)(μ‐tmp)Zn(Et)] ( 1 ) (PMDETA=N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine, TMP=2,2,6,6‐tetramethylpiperidide), and [(pmdeta)K(μ‐nBu)(μ‐tmp)Zn(nBu)] ( 2 ), have been synthesized by a simple co‐complexation procedure. Treatment of 1 with a series of substituted 4‐R‐pyridines (R=Me₂N, H, Et, iPr, tBu, and Ph) gave 2‐zincated products of the general formula [{2‐Zn(Et)₂‐μ‐4‐R‐C₅H₃N}₂ ? 2{K(pmdeta)}] ( 3 – 8 , respectively) in isolated crystalline yields of 53, 16, 7, 23, 67, and 51 %, respectively; the treatment of 2 with 4‐tBu‐pyridine gave [{2‐Zn(nBu)₂‐μ‐4‐tBu‐C₅H₃N}₂ ? 2{K(pmdeta)}] ( 9 ) in an isolated crystalline yield of 58 %. Single‐crystal X‐ray crystallographic and NMR spectroscopic characterization of 3 – 9 revealed a novel structural motif consisting of a dianionic dihydroanthracene‐like tricyclic ring system with a central diazadicarbadizinca (ZnCN)₂ ring, face‐capped on either side by PMDETA‐wrapped K⁺ cations. All the new metalated pyridine complexes share this dimeric arrangement. As determined by NMR spectroscopic investigations of the reaction filtrates, those solutions producing 3 , 7 , 8 , and 9 appear to be essentially clean reactions, in contrast to those producing 4 , 5 , and 6 , which also contain laterally zincated coproducts. In all of these metalation reactions, the potassium–zincate base acts as an amido transfer agent with a subsequent ligand‐exchange mechanism (amido replacing alkyl) inhibited by the coordinative saturation, and thus, low Lewis acidity of the 4‐coordinate Zn centers in these dimeric molecules. Studies on analogous trialkyl–zincate reagents in the absence and presence of stoichiometric or substoichiometric amounts of TMP(H) established the importance of Zn? N bonds for efficient zincation.     

Stepwise Formation of a 1,3‐Butadiene Analogue of Mixed Heavier Group 15 Elements

The reaction of the phosphinidene complex [Cp*P{W(CO)₅}₂] ( 1 a ) with di‐tert‐butylcarboimidophosphene leads to the P? C cage compound 6 and the Lewis acid–base adduct [Cp*P{W(CO)₅}₂(CNtBu)] ( 2 a ). In contrast, the arsinidene complex shows a different reactivity. At low temperatures, the arsaphosphene complex [{W(CO)₅}{η²‐(Cp*)As?P(tBu)}{W(CO)₅}] ( 3 ) is formed. At these temperatures, 3 reacts further with a second equivalent of carboimidophosphene to form [{W(CO)₅}{η²‐{(Cp*)(tBu)P}As?P(tBu)}{W(CO)₅}] ( 5 ), probably by the insertion of a phosphinidene unit (tBuP) into an As? C bond. In contrast, at room temperature 3 reacts further by a radical‐type reaction to form [{(tBu)P?As? As?P(tBu)}{W(CO)₅}₄] ( 4 ). Compound 4 is the first example of a neutral, 1,3‐butadiene analogue containing only mixed heavier Group 15 elements. It consists of two P?As double bonds connected by arsenic atoms.     

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.     

Sterically Less‐Hindered Half‐Titanocene(IV) Phenoxides: Ancillary‐Ligand Effect on Mono‐, Bis‐, and Tris(2‐Alkyl‐/arylphenoxy) Titanium(IV) Chloride Complexes

A series of mono‐, bis‐, and tris(phenoxy)–titanium(IV) chlorides of the type [Cp*Ti(2‐R? PhO)_nCl_3?n] (n=1–3; Cp*=pentamethylcyclopentadienyl) was prepared, in which R=Me, iPr, tBu, and Ph. The formation of each mono‐, bis‐, and tris(2‐alkyl‐/arylphenoxy) series was authenticated by structural studies on representative examples of the phenyl series including [Cp*Ti(2‐Ph? PhO)Cl₂] ( 1 PhCl2 ), [Cp*Ti(2‐Ph? PhO)₂Cl] ( 2 PhCl ), and [Cp*Ti(2‐Ph? PhO)₃] ( 3 Ph ). The metal‐coordination geometry of each compound is best described as pseudotetrahedral with the Cp* ring and the 2‐Ph? PhO and chloride ligands occupying three leg positions in a piano‐stool geometry. The mean Ti? O distances, observed with an increasing number of 2‐Ph? PhO groups, are 1.784(3), 1.802(4), and 1.799(3) Å for 1 PhCl2 , 2 PhCl , and 3 Ph , respectively. All four alkyl/aryl series with Me, iPr, tBu, and Ph substituents were tested for ethylene homopolymerization after activation with Ph₃C⁺[B(C₆F₅)₄]^? and modified methyaluminoxane (7% aluminum in isopar E; mMAO‐7) at 140 °C. The phenyl series showed much higher catalytic activity, which ranged from 43.2 and 65.4 kg (mmol of Ti?h)^?1, than the Me, iPr, and tBu series (19.2 and 36.6 kg (mmol of Ti?h)^?1). Among the phenyl series, the bis(phenoxide) complex of 2 PhCl showed the highest activity of 65.4 kg (mmol of Ti?h)^?1. Therefore, the catalyst precursors of the phenyl series were examined by treating them with a variety of alkylating reagents, such as trimethylaluminum (TMA), triisobutylaluminum (TIBA), and methylaluminoxane (MAO). In all cases, 2 PhCl produced the most catalytically active alkylated species, [Cp*Ti(2‐Ph? PhO)MeCl]. This enhancement was further supported by DFT calculations based on the simplified model with TMA.     

First‐Row Transition‐Metal–Diborane and –Borylene Complexes

A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp*CoCl}₂] (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with LiBH₄ ? thf at ?78 °C, followed by room‐temperature reaction with three equivalents of [Mn₂(CO)₁₀] yielded a manganese hexahydridodiborate compound [{(OC)₄Mn}(η⁶‐B₂H₆){Mn(CO)₃}₂(μ‐H)] ( 1 ) and a triply bridged borylene complex [(μ₃‐BH)(Cp*Co)₂(μ‐CO)(μ‐H)₂MnH(CO)₃] ( 2 ). In a similar fashion, [Re₂(CO)₁₀] generated [(μ₃‐BH)(Cp*Co)₂(μ‐CO)(μ‐H)₂ReH(CO)₃] ( 3 ) and [(μ₃‐BH)(Cp*Co)₂(μ‐CO)₂(μ‐H)Co(CO)₃] ( 4 ) in modest yields. In contrast, [Ru₃(CO)₁₂] under similar reaction conditions yielded a heterometallic semi‐interstitial boride cluster [(Cp*Co)(μ‐H)₃Ru₃(CO)₉B] ( 5 ). The solid‐state X‐ray structure of compound 1 shows a significantly shorter boron–boron bond length. The detailed spectroscopic data of 1 and the unusual structural and bonding features have been described. All the complexes have been characterized by using ¹H, ¹¹B, ¹³C NMR spectroscopy, mass spectrometry, and X‐ray diffraction analysis. The DFT computations were used to shed light on the bonding and electronic structures of these new compounds. The study reveals a dominant B?H?Mn, a weak B?B?Mn interaction, and an enhanced B?B bonding in 1 .     

Dreiecksdodekaedrische Heterotri‐ und ‐tetrametall‐Eisen–Ruthenium‐Cluster mit CpR‐ und Pn‐Liganden (n = 5, 4)

Triangulated Dodecahedral Heterotrimetallic‐ and ‐tetrametallic Iron–Ruthenium Clusters with Cp^R and P_n Ligands (n = 5, 4) The cothermolysis of [Cp*Fe(η⁵‐P₅)] ( 1 ) and [{Cp″(OC)₂Ru}₂](Ru–Ru) ( 2 ), Cp″ = C₅H₃But₂‐1,3, affords low yields of [Cp″Ru(η⁵‐P₅)] ( 3 ) and [{Cp″Ru}₂P₄] ( 4 ) as well as the triangulated dodecahedral hetero‐ and homotrimetallic clusters [{Cp″Ru}₂{Cp*Fe}P₅] ( 5 ), [{Cp″Ru}₃P₅] ( 6 ), [{Cp*Fe}₂{Cp″Ru}P₅] ( 7 ) and the tetranuclear compound [{Cp″Ru}₃{Cp*Fe}P₄] ( 8 ). X‐ray crystallographic studies show that the P₅ ligand in the distorted M₂M′P₅‐triangulated dodecahedra of 5 and 7 offers an unusual novel coordination mode derived from the educt 1 .     

Zur Reaktivität von alkylthioverbrückten 44‐CVE‐triangularen Platinclustern: Umsetzungen mit bidentaten Phosphanliganden

On the Reactivity of Alkylthio Bridged 44 CVE Triangular Platinum Clusters: Reactions with Bidentate Phosphine Ligands The 44 cve (cluster valence electrons) triangular platinum clusters [{Pt(PR₃)}₃(μ‐SMe)₃]Cl (PR₃ = PPh₃, 2a ; P(4‐FC₆H₄)₃, 2b ; P(n‐Bu)₃, 2c ) were found to react with PPh₂CH₂PPh₂ (dppm) in a degradation reaction yielding dinuclear platinum(I) complexes [{Pt(PR₃)}₂(μ‐SMe)(μ‐dppm)]Cl (PR₃ = PPh₃, 3a ; P(4‐FC₆H₄)₃, 3b ; P(n‐Bu)₃; 3e ) and the platinum(II) complex [Pt(SMe)₂(dppm)] ( 4 ), whereas the addition of PPh₂CH₂CH₂PPh₂ (dppe) to cluster 2a afforded a mixture of degradation products, among others the complexes [Pt(dppe)₂] and [Pt(dppe)₂]Cl₂. On the other hand, the treatment of cluster 2a with PPh₂CH₂CH₂CH₂PPh₂ (dppp) ended up in the formation of the cationic complex [{Pt(dppp)}₂(μ‐SMe)₂]Cl₂ ( 5 ). Furthermore, the terminal PPh₃ ligands in complex 3a proved to be subject to substitution by the stronger donating monodentate phosphine ligands PMePh₂ and PMe₂Ph yielding the analogous complexes [{Pt(PR₃)}₂(μ‐SMe)(μ‐dppm)]Cl (PR₃ = PMePh₂, 3c ; PMe₂Ph, 3d ). NMR investigations on complexes 3 showed an inverse correlation of Tolmans electronic parameter ν with the coupling constants ¹J(Pt,P) and ¹J(Pt,Pt). All compounds were fully characterized by means of NMR and IR spectroscopy. X‐ray diffraction analyses were performed for the complexes [{Pt{P(4‐FC₆H₄)₃}}₂(μ‐SMe)(μ‐dppm)]Cl ( 3b ), [Pt(SMe)₂(dppm)] ( 4 ), and [{Pt(dppp)}₂(μ‐SMe)₂]Cl₂ ( 5 ).