Silica-Grafted Tris(neopentyl)aluminum: A Monomeric Aluminum Solid Co-catalyst for Efficient Nickel-Catalyzed Ethene Dimerization

A silica-supported monomeric alkylaluminum co-catalyst was prepared via surface organometallic chemistry by contacting tris(neopentyl)aluminum and partially dehydroxylated silica. This system, fully characterized by solid-state ²⁷Al NMR spectroscopy augmented by computational studies, efficiently activates (ⁿBu₃P)₂NiCl₂ towards dimerization of ethene, demonstrating comparable activity to previously reported dimeric diethylaluminum chloride supported on silica. Three types of aluminum surface species have been identified: monografted tetracoordinated Al species as well as two types of bisgrafted Al species—tetra- and pentacoordinated. Of them, only the monografted Al species is proposed to be able to activate the (ⁿBu₃P)₂NiCl₂ complex and generate the active cationic species.     

Alkyne Metathesis with Silica‐Supported and Molecular Catalysts at Parts‐per‐Million Loadings

Improvement of the activity, stability, and chemoselectivity of alkyne‐metathesis catalysts is necessary before this promising methodology can become a routine method to construct C≡C triple bonds. Herein, we show that grafting of the known molecular catalyst [MesC≡Mo(OtBu_F6)₃] ( 1 , Mes=2,4,6‐trimethylphenyl, OtBu_F6=hexafluoro‐tert‐butoxy) onto partially dehydroxylated silica gave a well‐defined silica‐supported active alkyne‐metathesis catalyst [(≡SiO)Mo(≡CMes)(OtBu_F6)₂] ( 1 /SiO_2‐700). Both 1 and 1 /SiO_2‐700 showed very high activity, selectivity, and stability in the self‐metathesis of a variety of carefully purified alkynes, even at parts‐per‐million catalyst loadings. Remarkably, the lower turnover frequencies observed for 1 /SiO_2‐700 by comparison to 1 do not prevent the achievement of high turnover numbers. We attribute the lower reactivity of 1 /SiO_2‐700 to the rigidity of the surface Mo species owing to the strong interaction of the metal site with the silica surface.     

Reactivity of mixed organozinc and mixed organocopper reagents: 11. Nickel‐catalyzed atom‐economic aryl–allyl coupling of mixed (n‐alkyl)(aryl)zincs

Group selectivity in the allylation of mixed (n‐butyl)(phenyl)zinc reagent can be controlled by changing reaction parameters. CuCN‐catalyzed allylation in tetrahydrofuran (THF)–hexamethylphosphoric triamide is n‐butyl selective and also γ‐selective in the presence of MgCl₂, whereas CuI‐catalyzed allylation in THF in the presence of n‐Bu₃P takes place with a n‐butyl transfer:phenyl transfer ratio of 23:77 and an α:γ transfer ratio of phenyl of 76:24. NiCl₂(Ph₃P)₂‐catalyzed allylation in the presence of LiCl is phenyl selective with an α:γ ratio of 65:35. The reaction of methyl‐ or n‐butyl(aryl)zinc reagents with an allylic electrophile in THF at room temperature in the presence of NiCl₂(Ph₃P)₂ catalyst and LiCl as an additive provides an atom‐economic alternative to aryl–allyl coupling using diarylzincs. Copyright © 2014 John Wiley & Sons, Ltd.     

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

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

Synthesis and oxidative degradation of poly(ethene‐ran‐1,3‐butadiene)

Copolymerization of ethene and 1,3‐butadiene was conducted over SiO₂‐supported CpTiCl₃ catalyst using Ph₃CB(C₆F₅)₄ or B(C₆F₅)₃ combined with triisobutylaluminium (ⁱBu₃Al) or trioctylaluminium (Oct₃Al). When the copolymerization was carried out at 0°C, the Ph₃CB(C₆F₅)₄/ⁱBu₃Al and B(C₆F₅)₃/Oct₃Al systems selectively produced copolymers which contained about 0.5–2.5 mol‐% of trans‐1,4‐inserted butadiene units. The number‐average molecular weight (M_n) of the copolymers was around 80 000 with polydispersities in the range from 6 to 8. Oxidative degradation of the vinylene units with potassium permanganate decreased the M_n values to several thousands with polydispersities of ca. 2. This indicates that the butadiene units are randomly distributed in the copolymers. NMR analysis clarified that the decomposed product is a polyethene with carboxyl groups at both chain ends.     

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

The Wilkinson’s catalyst [RhCl(PPh₃)₃] has been immobilized inside the pores of amine functionalized mesoporous silica material SBA‐3 and The structure of the modified silica surface and the immobilized rhodium complex was determined by a combination of different solid‐state NMR methods. The successful modification of the silica surface was confirmed by ²⁹Si CP‐MAS NMR experiments. The presence of the T_n peaks confirms the successful functionalization of the support and shows the way of binding the organic groups to the surface of the mesopores. ³¹P‐³¹P J‐resolved 2D MAS NMR experiments were conducted in order to characterize the binding of the immobilized catalyst to the amine groups of the linkers attached to the silica surface. The pure catalyst exhibits a considerable ³¹P‐³¹P J‐coupling, well resolvable in 2D MAS NMR experiments. This J‐coupling was utilized to determine the binding mode of the catalyst to the linkers on the silica surface and the number of triphenylphosphine ligands that are replaced by coordination bonds to the amine groups. From the absence of any resolvable ³¹P‐³¹P J‐coupling in off‐magic‐angle‐spinning experiments, as well as slow‐spinning MAS experiments, it is concluded, that two triphenylphosphine ligands are replaced and that the catalyst is bonded to the silica surface through two linker molecules.     

Ultra‐wideline 27Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Ultra‐wideline ²⁷Al NMR experiments are conducted on coordination compounds with ²⁷Al nuclei possessing immense quadrupolar interactions that result from exceptionally nonspherical coordination environments. NMR spectra are acquired using a methodology involving frequency‐stepped, piecewise acquisition of NMR spectra with Hahn‐echo or quadrupolar Carr–Purcell Meiboom–Gill (QCPMG) pulse sequences, which is applicable to any half‐integer quadrupolar nucleus with extremely broad NMR powder patterns. Despite the large breadth of these central transition powder patterns, ranging from 250 to 700 kHz, the total experimental times are an order of magnitude less than previously reported experiments on analogous complexes with smaller quadrupolar interactions. The complexes examined feature three‐ or five‐coordinate aluminum sites: trismesitylaluminum (AlMes₃), tris(bis(trimethylsilyl)amino)aluminum (Al(NTMS₂)₃), bis[dimethyl tetrahydrofurfuryloxide aluminum] ([Me₂‐Al(μ‐OTHF)]₂), and bis[diethyl tetrahydrofurfuryloxide aluminum] ([Et₂‐Al(μ‐OTHF)]₂). We report some of the largest ²⁷Al quadrupolar coupling constants measured to date, with values of C_Q(²⁷Al) of 48.2(1), 36.3(1), 19.9(1), and 19.6(2) MHz for AlMes₃ , Al(NTMS₂)₃ , [Me₂‐Al(μ‐OTHF)]₂ , and [Et₂‐Al(μ‐OTHF)]₂ , respectively. X‐ray crystallographic data and theoretical (Hartree–Fock and DFT) calculations of ²⁷Al electric field gradient (EFG) tensors are utilized to examine the relationships between the quadrupolar interactions and molecular structure; in particular, the origin of the immense quadrupolar interaction in the three‐coordinate species is studied via analyses of molecular orbitals.     

Preparation and Characterization of Aluminum Alkoxides and their Application to Ring‐Opening Polymerization of ϵ‐Caprolactones

The reaction of 2‐methoxybenzyl alcohol with one molar equiv of R₂AIX in diethyl ether at 0°C gives [(2‐MeOC₆H₄CH₂‐μ‐O)AlRX]₂ ( 1 : R = Et, X = Cl, 2 : R = X = Et). In addition, 2,4‐di‐tert‐butylphenol reacts with ⁱBu₃Al affording a four‐coordinated aluminum compound [(μ‐2,4‐^tBu₂‐C₆H₄O)Al(ⁱBu)₂]₂ ( 4 ). Single crystal X‐ray structure analysis of 4 shows a C_2h‐symmetry with a planar Al₂O₂ core. Ring‐opening polymerization (ROP) of caprolactones initiated by 1, 4 and [(μ‐OCH₂C₆H₄OMe)Al(ⁱBu)₂]₂ ( 3 ) is performed and polyesters with narrow molecular weight distributions were obtained from the “living” ROP of caprolactones. ¹H NMR spectroscopic studies of PCL reveal that the initiator of 1 and 3 is through the Al‐OAr function, but the initiator of 4 is through the Al‐ ⁱBu group.     

Molecular and Silica‐Supported Mo and W d0 Imido‐Methoxybenzylidene Complexes: Structure and Metathesis Activity

5‐Coordinated methoxybenzylidene complexes M(=NAr)(=CH?C₆H₄?o‐OMe)(O^tBu_F3)₂ (Ar=2,6‐ⁱPr₂C₆H₃; ^tBu_F3=CMe₂(CF₃)) of Mo ( 1m_Mo ) and W ( 1m_W ) were synthesized by cross‐metathesis from the corresponding neophylidene/neopentylidene precursors and o‐methoxystyrene. 1m_Mo and 1m_W were grafted onto the surface of silica partially dehydroxylated at 700 °C to give well‐defined silica‐supported alkylidenes (≡SiO)M(=NAr)(=CH?C₆H₄?o‐OMe)(O^tBu_F3) (M=Mo ( 1_Mo ), W ( 1_W )). Supported methoxybenzylidene complexes were tested in metathesis of cis‐4‐nonene, 1‐nonene, and ethyl oleate, and compared to their molecular precursors and supported classical analogs (≡SiO)M(=NAr)(=CHCMe₂R)(O^tBu_F3) (M=Mo, R=Ph ( 2_Mo ), M=W, R=Me ( 2_W )). Both grafted complexes 1_Mo and 1_W show significantly better performance as compared to their molecular precursors 1m_Mo and 1m_W but are less efficient than the classical 4‐coordinated alkylidenes 2_Mo and 2_W . Noteworthy, both 1_Mo and 1_W can reach equilibrium conversion in metathesis of cis‐4‐nonene at catalyst loadings as low as 50 ppm.     

Kohlenwasserstoffverbrückte Metallkomplexe. L Dicarbonyl‐cyclopentadienyl‐pyridoyl‐eisen‐Komplexe als Liganden

Hydrocarbon‐bridged Metal Complexes. L Dicarbonyl Cyclopentadienyl Pyridoyl Iron Complexes as Ligands Dicarbonyl‐cyclopentadienyl‐2‐ and 3‐pyridoyl‐iron (L¹, L²) and 2,6‐dicarbonyl‐pyridine‐bis(dicarbonyl‐cyclopentadienyl‐iron) (L³) function as ligands in metal complexes and the N,O‐chelates [(OC)₄M(L¹)] (M = Mo, W, 8 a, b ) and [(Ph₃P)₂Cu(L¹)]⁺BF₄^– ( 9 ) were prepared. Monodentate coordination of L¹ and L² through the pyridine N‐atom occurs in the palladium(II) complexes [Cl₂Pd(PnBu₃)(L¹)] ( 10 ), [Cl₂Pd(PnBu₃)(L²)] ( 11 ) and [Cl₂Pd(L²)₂] ( 12 ). Ligand L³ forms the O,N,O‐bis(chelate) [Cl₂Zn(L³)] ( 13 ). The crystal and molecular structures of L¹, 8 b (M = W), 9–11 and 13 were determined by X‐ray diffraction.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen der Tetrahalogeno‐bis‐Pyridin‐Osmium(III)‐Komplexe cis‐(n‐Bu4N)[OsCl4Py2] und trans‐(n‐Bu4N)[OsX4Py2], X = Cl,Br

Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Tetrahalogeno‐bis‐Pyridine‐Osmium(III) Complexes cis ‐( n ‐Bu₄N)[OsCl₄Py₂] and trans ‐( n ‐Bu₄N)[OsX₄Py₂], X = Cl, Br By reaction of (n‐Bu₄N)₂[OsX₆], X = Cl, Br, with pyridine and (n‐Bu₄N)[BH₄] tetrahalogeno‐bis‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of cis‐(n‐Bu₄N)[OsCl₄Py₂] ( 1 ) (triclinic, space group P1, a = 9.4047(9), b = 10.8424(18), c = 17.007(2) Å, α = 71.833(2), β = 81.249(10), γ = 67.209(12)°, Z = 2), trans‐(n‐Bu₄N)[OsCl₄Py₂] ( 2 ) (orthorhombic, space group P2₁2₁2₁, a = 8.7709(12), b = 20.551(4), c = 17.174(4) Å, Z = 4) and trans‐(n‐Bu₄N)[OsBr₄Py₂] ( 3 ) (triclinic, space group P1, a = 9.132(3), b = 12.053(3), c = 15.398(2) Å, α = 95.551(18), β = 94.12(2), γ = 106.529(19)°, Z = 2). Based on the molecular parameters of the X‐ray structure determinations and assuming C₂ point symmetry for the anion of 1 and D_2h point symmetry for the anions of 2 and 3 the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants of 1 are in the Cl–Os–Cl axis f_d(OsCl) = 1.58, in the asymmetrically coordinated N′–Os–Cl ^· axes f_d(OsCl ^· ) = 1.45, f_d(OsN′) = 2.48, of 2 f_d(OsCl) = 1.62, f_d(OsN) = 2.42 and of 3 f_d(OsBr) = 1.39 and f_d(OsN) = 2.34 mdyn/Å.     

Terminally Dimetallated N,N′‐Dimethylpiperazines with Doubly Spirocyclic Structures

Dilithiated N,N′‐dimethyl‐piperazine, LiCH₂N(CH₂CH₂)₂ NCH₂Li ( 2 ) was prepared by transmetallation of N,N′‐bis(trimethylstannylmethyl)‐piperazine ( 1 ) with ⁿBuLi and was isolated as a highly pyrophoric yellowish powder in high yield. Compound 2 was characterized by elemental analysis and was reacted as difunctional aminomethylating reagent with dialkyl‐earth metal chlorides, R₂MCl (M = Al, Ga; R = Me, ^tBu) which resulted in the formation of spirocyclic adducts of N,N′‐bis(dialkylmetallamethyl)‐piperazine and unreacted dialkylmetal chlorides, [(Me₂AlCl)Me₂AlCH₂N(CH₂CH₂)₂NCH₂AlMe₂(ClAlMe₂)] ( 3 ) and [(^tBu₂GaCl)^tBu₂GaCH₂N(CH₂CH₂)₂NCH₂Ga^tBu₂(ClGa^tBu₂)] ( 4 ) with five‐membered rings. Compounds 1 , 3 and 4 were identified by NMR‐spectroscopy (¹H, ¹³C, ¹¹⁹Sn for 1 , ²⁷Al for 3 ), mass spectra (EI, for 1 ) and by crystal structure determinations.     

Synthesis and Molecular Structure of [n‐Bu2(F)SnOSn(F)t‐Bu2]2 — an Unsymmetrically Substituted Tetraorganodistannoxane

The dimeric tetraorganodistannoxane [n‐Bu₂(F)SnOSn(F)t‐Bu₂]₂ ( 1 ) was prepared by the reaction of (t‐Bu₂SnO)₃ with n‐Bu₂SnF₂ and characterized in solution by multinuclear NMR spectroscopy and ESI MS spectrometry and in the solid state by ¹¹⁹Sn MAS NMR spectroscopy and single crystal X‐ray diffraction.     

Phosphido‐diphosphine pincer aluminum complexes as catalysts for ring opening polymerization of cyclic esters

New aluminum alkyl complexes, supported by o‐phenylene‐derived phosphido diphosphine pro‐ligands [Ph‐PPP]‐H and [ⁱPr‐PPP]‐H ([Ph‐PPP]‐H = bis(2‐diphenylphosphinophenyl)phosphine; [ⁱPr‐PPP]‐H = bis(2‐diisopropylphosphinophenyl)phosphine) are reported. Compounds [Ph‐PPP]AlMe₂ ( 1 ), [ⁱPr‐PPP]AlMe₂ ( 2 ), and [Ph‐PPP]AlⁱBu₂ ( 3 ) have been synthesized by reaction of the pro‐ligand with the appropriate trialkyl aluminum precursor and have been characterized by ¹H, ¹³C and ³¹P NMR spectroscopy. The solution NMR data and theoretical calculations suggest for all complexes trigonal bipyramidal structures with C_2v symmetry in which the phosphido diphosphine ligand acts as a κ³ coordinated ligand. All complexes promote the ring‐opening polymerization of ε‐caprolactone, L‐ and rac‐lactide. Polyesters with controlled molecular parameters (M_n, end groups) and low polydispersities are obtained. Upon addition of isopropanol, efficient binary catalytic systems for the immortal ring‐opening polymerization of the cyclic esters are produced. Preliminary investigations show the ability of these complexes to promote copolymerization of l ‐lactide and ?‐caprolactone to achieve copolymers whose microstructures are depending on the structure of the catalyst. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 49–60     

Synthesis and Characterization of trans‐PdII Trimethylsilylchalcogenolates

The trans‐bis(trimethylsilyl)chalcogenolate palladium complexes, trans‐[Pd(ESiMe₃)₂(PnBu₃)₂] [E = S ( 1 ) and Se ( 2 )] were synthesized in good yields and high purity by reacting trans‐[PdCl₂(PBu₃)₂] with LiESiMe₃ (E = S, Se), respectively. These complexes were characterized by ¹H, ¹³C{¹H}, ³¹P{¹H} (and ⁷⁷Se{¹H}) NMR spectroscopy and single‐crystal X‐ray analysis. The reaction of 2 with propionyl chloride led to the formation of trans‐[Pd(SeC(O)CH₂CH₃)₂(PnBu₃)₂] ( 3 ), a trans‐bis(selenocarboxylato) palladium complex and thus established a new method for the formation of this type of complex. Complex 3 was characterized by ¹H, ¹³C{¹H}, ³¹P{¹H} and ⁷⁷Se{¹H} NMR spectroscopy and a single‐crystal X‐ray structure analysis.     

Rapid and Scalable Access to Sequence‐Controlled DHDM Multiblock Copolymers by FLP Polymerization

An immortal N‐(diphenylphosphanyl)‐1,3‐diisopropyl‐4,5‐dimethyl‐1,3‐dihydro‐2H‐imidazol‐2‐imine/diisobutyl (2,6‐di‐tert‐butyl‐4‐methylphenoxy) aluminum (P(NIⁱPr)Ph₂/(BHT)AlⁱBu₂)‐based frustrated Lewis pair (FLP) polymerization strategy is presented for rapid and scalable synthesis of the sequence‐controlled multiblock copolymers at room temperature. Without addition of extra initiator or catalyst and complex synthetic procedure, this method enabled a tripentacontablock copolymer (n=53, k=4, dp_n=50) to be achieved with the highest reported block number (n=53) and molecular weight (M_n=310 kg mol^?1) within 30 min. More importantly, this FLP polymerization strategy provided access to the multiblock copolymers with tailored properties by precisely adjusting the monomer sequence and block numbers.     

Regiodirected Synthesis and Stereochemistry of 2,4,8‐Trialkyl‐3‐thia‐1,5‐diazabicyclo[3.2.1]octanes and α,ω‐Bis(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)alkanes

2,4,8‐Trialkyl‐3‐thia‐1,5‐diazabicyclo[3.2.1]octanes have been obtained by the regioselective and stereoselective cyclocondensation of 1,2‐ethanediamine with aldehydes RCHO (R═Me, Et, Prⁿ, Buⁿ, Pentⁿ) and H₂S at molar ratio 1:3:2 at 0°C. The increase in molar ratio of thiomethylation mixture RCHO–H₂S (6:4) at 40°C resulted in selective formation of bis‐(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)ethanes. Cyclothiomethylation of aliphatic α,ω‐diamines with aldehydes RCHO (R═Me, Et) and H₂S at molar ratio 1:6:4 and at 40°С led to α,ω‐bis(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)alkanes. Stereochemistry of 2,4,8‐trialkyl‐3‐thia‐1,5‐diazabicyclo[3.2.1]octanes have been determined by means of ¹H and ¹³С NMR spectroscopy and further supported by DFT calculations at the B3LYP/6‐31G(d,p) level. The structure of α,ω‐bis(2,4,6‐trialkyl‐1,3,5‐dithiazinane‐5‐yl)alkanes was confirmed by single‐crystal X‐ray diffraction study.     

Generation and Reactivity of {(Ethane‐1,2‐diyl)bis[diisopropylphosphine‐κP]}‐{[2,4,6‐tri(tert‐butyl)phenyl]phosphino‐κP}rhodium ([Rh{PH(tBu3C6H2)}(iPr2PCH2CH2PiPr2)]): Catalytic C−P Bond Formation via Intramolecular C−H/P−H Dehydrogenative Cross‐Coupling

The complex [Rh(η³‐benzyl)(dippe)] ( 1 ; dippe=bis(diisopropylphosphino)ethane=(ethane‐1,2‐diyl)bis[diisopropylphosphine]) reacted cleanly with Mes*PH₂ ( 2 ; Mes*=2,4,6‐^tBu₃C₆H₂) to provide a new Rh species [Rh(H)(dippe)(L)] ( 3 ), L being the 2,3‐dihydro‐3,3‐dimethyl‐1H‐phosphindole ligand 4 (=^tBu₂C₆H₂(CMe₂CH₂PH)) (Scheme 1). Complex 3 was converted to the corresponding chloride [Rh(Cl)(dippe)(L)] ( 6 ) when treated with CH₂Cl₂, whereas the dimeric species [Rh₂{μ‐^tBu₂C₆H₂(CMe₂CH₂P)}(μ‐H)(dippe)₂] ( 7 ) was formed upon thermolysis in toluene (Scheme 2). The structures of 6 and 7 ⋅C₇H₈ were determined by X‐ray crystallography. Complexes 1 and 3 served as catalyst precursors for the dehydrogenative coupling of C−H and P−H bonds in the conversion of 2 to 4 (Scheme 3). Deuteration studies with Mes*PD₂ exposed a complex series of bond‐activation pathways that appear to involve C−H activation of the dippe ligand by the Rh‐atom (Schemes 4 and 5)     

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

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

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.