Various [Cr(CO)4(P∩P)]+ complexes have been synthesized and tested for the tetramerization of ethylene to give principally 1-octene. The effect anion has investigated, it found that successful catalysis an extremely weakly coordinating is required. This study shows when [Al(OC(CF3)3)4]- employed as anion, along with triethylaluminum PNPiPr coordinated diphosphine, system active ethylene. first example CrI being used a catalyst precursor selective gives evidence toward catalytic cycle acting...

Dimethylindenyl-functionalized N-heterocyclic carbene complexes of titanium(IV), titanium(III), zirconium(IV), and vanadium(III) were prepared from potassium indenylcarbenes by salt elimination reactions. X-ray diffraction studies revealed that in the ligand adopts a bidentate coordination mode. Alkanolysis dimethylindene-functionalized imidazolium with Y(CH2SiMe3)3(THF)2 gave rise to dimeric yttrium bromo alkyl which coodination Aminolysis fluorene-functionalized salts...

The rigid bidentate P,N-ligands 3a−d (phosphino substituent: a, Ph; b, mes; c, N-i-Pr2; d, NPh2), each with a 7-phosphino-1,5,7-triazabicyclo[4.4.0]dec-5-ene skeleton, are readily prepared in high yields and have been used the preparation of nickel complexes [NiBr2(3a−d)] (4a−d). derivatives 4a,d both diamagnetic, while their counterparts 4b,c paramagnetic values μeff(300 K) 2.05 2.10 μB, respectively. structure 4a has determined solid state by X-ray diffraction, which confirmed κ2P,N...

This report examines the replacement of imine and pyridine functionalities ubiquitous bis(imino)pyridine ligand with various heterocycles. The synthesis a new class based around thiazole is described; 2,4-bis[1-(arylimino)ethyl]thiazole (aryl = Ph, 1a; Dipp, 1b) 2,5-bis[1-(arylimino)ethyl]thiazole 1c; 1d) have been prepared in good yield fully characterized. coordination chemistry these ligands chromium, iron, cobalt explored, potential complexes as ethylene oligomerization initiators...

1-Phosphanyl methanimine ligands, R2P–C(Ph)═NR′, may be prepared via a modular, convergent synthesis in good overall yield. Coordination chemistry studies with chromium confirm that they bind bidentate κ2-P,N mode. In combination and an activator, these ligands promote the selective oligomerization of ethylene to 1-hexene 1-octene high activity. Notably, exceptionally liquid fraction selectivity saleable products (1-hexene + 1-octene) is observed (>95%), along potent ligand dependence, such...

New ruthenium carbene complexes 5 and 6, containing a rigid bicyclic phosphine moiety, have been prepared, the structure of has unambiguously established by single-crystal X-ray diffraction studies. These ruthenium-based show excellent stability to air moisture, can be recycled chromatography, are available from simple precursors. They efficient catalysts for various metathesis reactions, particularly applications where high selectivity is required.

Ligand backbone alkylation of the complex [Cr(CO)4(dppm)] (dppm = bis(diphenylphosphino)methane) with alkyl iodides yields C-substituted dppm ligand complexes [Cr(CO)4{Ph2PCH(R)PPh2}] (R methyl, n-hexyl, benzyl). Activation these via one-electron oxidation Ag[(Al(OC4F9)4] and CO removal triethylaluminium, or (in case R methyl) by in situ treatment free a chromium salt modified methyl alumoxane (MMAO), leads to catalysts showing some selectivity for ethylene trimerization tetramerization. NMR...

The new ambiphilic ligand Ph2P–(1,1′-ferrocenyl)–BMes2, prepared by sequential lithiation/electrophilic trapping of 1,1′-dibromoferrocene, adopts a monomeric structure free dative P → B and Fe interactions. This flexible phosphine-borane the related o-phenylene bridged system have been evaluated in Rh-catalyzed hydroformylation.

Desilylation of the 2-phosphinophosphinine 2-PPh2-3-Me-6-SiMe3-PC5H2 with HCl gave 2-PPh2-3-Me-PC5H3, demonstrating late-stage modification this bidentate heterocyclic ligand. Group 6 metal carbonyl complexes these ligands showed κ2 binding and very small bite angles 65.1–68.3°, also demonstrated that donor properties 2-phosphinophosphinines can be tuned readily by presence SiMe3 group, which gives a more π accepting phosphinine The were compared to those diphosphorus computationally,...

The coordination chemistry of a range dialkylamino- and bis(dialkylamino)-phosphines, RxP(NR′2)3 − x (x = 1 or 2; R Cl, Me, Ph, C6F5; R′ Et, Pri), 1–7, has been studied the resulting Group 6 tetracarbonyl platinum dichloride bis(phosphine) complexes fully characterised. Subsequently, reactivity P–N bonds metal-bound phosphines was probed. Treatment R″OH (R″ allyl) solutions bis(dialkylaminodiphenylphosphine) with anhydrous HCl gas led to substitution NR′2 by OR″; P-alkoxy were isolated in...

The chromium(III) complexes of the type L1CrXY (L1 = 1-(2,6-diisopropylphenyl)-3-[β-(4,7-dimethylindenyl)ethyl]-imidazol-2-ylidene, X, Y Cl, 2a-Cl; X Me, 2a-Me; Ph, 2a-Ph; benzyl, 2a-Bz) and L2CrCl2 (L2 1-(2,6-diisopropylphenyl)-3-[γ-(4,7-dimethylindenyl)propyl]-imidazol-2-ylidene, 2b-Cl) have been prepared characterized by analytical diffraction methods. salts [L1CrCl(THF)]+[BArF4]− [L2CrCl(THF)]+[BArF4]− (ArF 3,5-bis(trifluoromethyl)phenyl) were also characterized, having obtained...

The first example of a catalyst utilising sulfur-based ligand [MeC(CH2SBu)3] for the selective hydrogenation dimethyl oxalate to methyl glycolate is reported.

The use of AlEt3 (TEA) in combination with [Ph3C][Al(OtBuF)4] (TA) for the activation a range bis(imino)pyridine complexes vanadium, chromium, iron, and cobalt is reported. It shown that this activator successfully replaces MMAO, some cases showing improvements terms activity productivity. Furthermore, when activities productivities are considered aluminum center (MMAO vs TEA), true cost driver commercialization most catalyst systems, then nearly all significant improvement seen.

The interaction of triethylaluminum (TEA) with a solution the paramagnetic Cr(I) bis(phosphine) complex [Cr(CO)41][Al(OC(CF3)3)4] (1 = Ph2PN(iPr)PPh2) has been studied using EPR and DFT. It was found that TEA is responsible for complete removal all CO groups from [Cr(CO)41]+ complex, producing [Cr(1-bis-η6-arene)]+, this reaction occurs via dominant pathway involving series [Cr(CO)x1]+ (x < 4) intermediates, consistently including cis-[Cr(CO)31]+ (species A) "piano-stool"-type [Cr(CO)21]+...

A new family of N,N′-bis-(2,6-diisopropylphenyl)-(2,6-diisopropylphenyl-imidazolium)-acetamidines have been developed as NHC proligands and ligands that are functionalised with neutral amidine anionic amidinato moieties. On coordination they adopt diverse binding modes, depending on the nature metal reaction conditions. In Ag, K Cr complexes reported in this paper, monodentate κ1(NHC), bimetallic bridging-(κ1-NHC–κ1-amidinato) bidentate (κ1-NHC–κ1-amidinato) modes were observed,...

9-Amino-9-phosphabicyclo[3.3.1]nonanes, (PhobPNHR'; R = Me or (i)Pr) are readily prepared by aminolysis of PhobPCl and significantly less susceptible to hydrolysis than the acyclic analogues Cy2PNHR'. Treatment Cy2PNHMe with Cy2PCl gave Cy2PNMePCy2. By contrast, treatment PhobPNHMe in presence Et3N does not afford PhobPNMePPhob but instead salt [PhobP(= NMeH)PPhob]Cl is formed which, upon addition [PtCl2(NC(t)Bu)2] gives zwitterionic complex [PtCl3(PhobP(= NMeH)PPhob)]. The neutral PhobP(=...

The reaction of [WCl2(NAr)2(DME)] (1) with excess Me3Al affords the dimethyl complex [WMe2(N{Ar}AlMe2{μ-Cl})(NAr)] (2), which on treatment THF or MeAlCl2 yields [WMe2(NAr)2(THF)] (3) and [WMe2(N{Ar}AlMe(Cl){μ-Cl})(NAr)] (5), respectively. Complex 3 is unstable in solution dissociating to form [WMe2(NAr)2] (4) that may be isolated as an adduct PMe3, [WMe2(NAr)2(PMe3)] (6). While 2 inert towards ethylene, reacts rapidly afford a mixture methane but-1-ene (1 : 4). Neither nor react propylene....

Scandium trichloride complexes with tridentate N3- and S2N-donor ligands (L3) have been synthesised characterised by IR, 1H, 13C{1H} 45Sc NMR spectroscopy, microanalysis, solid state solution XAFS spectroscopy. Catalytic testing of a subset these ethene has undertaken in chlorobenzene MMAO-3A PMAO-IP at 60 °C 40 bar ethene, giving low activity polymerisation. The reactions MeLi AlMe3 were studied 13C{1H}, 27Al spectroscopy situ via Sc K-edge Three or four mol. equivalents react...

The preparation and characterisation of the Cr(I) complexes [Cr(CO)4L]+ (L = Ph2PN(R)PPh2, Ph2P(R)PPh2), which are used as pre-catalysts for selective oligomerization ethylene, reported. electronic properties structural features these in frozen solution have been established via continuous wave X-band Electron Paramagnetic Resonance (cw-EPR) 1H, 14N 31P Nuclear Double (cw-ENDOR) spectroscopy. EPR spectra dominated by g anisotropy, with notably large PA couplings from two equivalent nuclei....

Activation of the catalytically relevant complex [Cr(CO)4(1)]+ (1 = Ph2P(C3H6)PPh2) by Et3Al (TEA) leads to formation Cr(I) bis-arene [Cr(1-bis-η6-arene)]+, as revealed EPR and DFT calculations. This is formed intramolecular rearrangement coordination ligand phenyl groups in aliphatic solvents following loss CO, preventing release into solution. By comparison aromatic (toluene), [Cr(bis-tolyl)]+ preferentially formed.

The synthesis and full characterization of the unprecedented open-shell Cr(II) benzyl organometallic complexes [Cr(NHC)2(benzyl)2] (2) [Cr(NHC*)(benzyl)2] (3) (NHC = N,N′-diisopropylimidazol-2-ylidene; NHC* N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) from [Cr(benzyl)3(THF)3] [CrCl2(THF)2]/[Mg(benzyl)2], respectively, uncovered unusually acute angles (93° in 2 76° 3) at sp3 benzylic C coordinated ligands. Detailed theoretical analyses (DFT CASPT2) four- three-coordinate species were...

The selective dimerisation of the alpha-olefins 1-pentene through to 1-nonene is reported using an in situ-generated catalyst derived from tungsten hexachloride, aniline, triethylamine and alkylaluminium halide. influence reagent identity reaction stoichiometry, along with activator, solvent alpha-olefin substrate choice are probed. found be highly towards dimerisation, minimising formation undesired heavier oligomers. Notably, selectivity within dimer fraction favour products methyl...

In combination with EtAlCl(2) (Mo : Al = 1 15) the imido complexes [MoCl(2)(NR)(NR')(dme)] (R R' 2,6-Pr(i)(2)-C(6)H(3) (1); R 2,6-Pr(i)(2)-C(6)H(3), Bu(t) (3); (4); dme 1,2-dimethoxyethane) and [Mo(NHBu(t))(2)(NR)(2)] (5); (6)) each show moderate TON, activity, selectivity for catalytic dimerisation of ethylene, which is influenced by nature substituents. contrast, productivity [MoCl(2)(NPh)(2)(dme)] (2) low polymerisation favoured over dimerisation. Catalysis initiated 1-4 in MeAlCl(2)...