Ethylene Oligomerization by (dppe)MCl_2 [M = Fe(II), Co(II),Ni(II)] Complexes/EAO

Transition-metal-catalyzed oligomerzation of ethylene is an important process to provide a-olefins in the C6~C20 range. In recent years, the catalytic behavior of late transition metal complexes containing bi- and tri-dentate ligands for oligomerization of ethylene to a-olefins has attracted much attention. When oligomerization of ethylene catalyzed by nickel diimine and Fe(II), Co(II) 2,6-bis(imino)pyridine catalysts, the oligomers with high average molecular weight were obtained1-5. Eth…     

Catalytic Effect of Cobalt and Iron Complexes Incorporating Bis(2-aldiminoethyl)amine Ligands on Ethylene Oligomerization

IntroductionThe finding of a new promising family ofFe( ) - and Co( ) - based bis( imino) pyridyl cata-lysts for ethylene polymerization and oligomeriza-tion,discovered by Brookhart,Gibson andcoworkers[1— 3 ] ,has intrigued us into researchingthe preparation,the structure and the chemistry ofiron and cobalt complexes incorporating N,N ,N -tridentate ligands.The spectacular enhancement ofthe reactivity of iron and cobalt complexes towardsZiegler- Natta olefin polymerization has been re-po…     

Ethylene Oligomerization Catalyzed by Nickel（Ⅱ） Diimine Complexes

Ethylene oligomerization has been investigated by using catalyst systems composed of nickel(II) diimine complexes (diimine = N, N′‐o‐phenylene bis (salicylideneaminato), N, N′‐o‐phenylenebisbenzal, N, N′‐ethylenebisbenzal) and ethylaluminoxane (EAO). The main products in toluene and at 110–200 °C were olefins with low carbon numbers (C₄—C₁₀). Effects of reaction temperature, Al/Ni molar ratio and reaction period on both the catalytic activity and product distribution were explored. The activity of 1.84 × 10⁵ g of oligomer/(mol_NI · h), with 87.4% of selectivity to C₄—C₁₀ olefins, was attained at 200 °C in the reaction when a catalyst composed of NiCl₂ (PhCH = o‐NC₆H₄N = CHPh) and EAO was used.     

The Versatile Coordination Modes of Monophosphine‐o‐Carborane in the Formation of Iridium and Rhodium Complexes: Synthesis,Reactivity, and Characterization

Monophosphine‐o‐carborane has four competitive coordination modes when it coordinates to metal centers. To explore the structural transitions driven by these competitive coordination modes, a series of monophosphine‐o‐carborane Ir,Rh complexes were synthesized and characterized. [Cp*M(Cl)₂{1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁}] (M=Ir ( 1 a ), Rh ( 1 b ); Cp*=η⁵‐C₅Me₅), [Cp*Ir(H){7‐(PPh₂)‐7,8‐C₂B₉H₁₁}] ( 2 a ), and [1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 3 a ), Rh ( 3 b )) can be all prepared directly by the reaction of 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ with dimeric complexes [(Cp*MCl₂)₂] (M=Ir, Rh) under different conditions. Compound 3 b was treated with AgOTf (OTf=CF₃SO₃^?) to afford the tetranuclear metallacarborane [Ag₂(thf)₂(OTf)₂{1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐RhC₂B₉H₁₀}₂] ( 4 b ). The arylphosphine group in 3 a and 3 b was functionalized by elemental sulfur (1 equiv) in the presence of Et₃N to afford [1‐{(S)PPh₂}‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 5 a ), Rh ( 5 b )). Additionally, the 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ ligand was functionalized by elemental sulfur (2 equiv) and then treated with [(Cp*IrCl₂)₂], thus resulting in two 16‐electron complexes [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₉)] ( 6 a ) and [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐9‐OCH₃‐7,8‐C₂B₉H₉)] ( 7 a ). Compound 6 a further reacted with nBuPPh₂, thereby leading to 18‐electron complex [Cp*Ir(nBuPPh₂)(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₁₀)] ( 8 a ). The influences of other factors on structural transitions or the formation of targeted compounds, including reaction temperature and solvent, were also explored.     

High polymerization of methyl methacrylate with organonickel/MMAO systems

A series of nickel complexes, including Ni(acac)₂, (C₅H₅)Ni(η³‐allyl), and [NiMe₄Li₂(THF)₂]₂, that were activated with modified methylaluminoxane (MMAO) exhibited high catalytic activity for the polymerization of methyl methacrylate (MMA) but showed no catalytic activity for the polymerization of ethylene and 1‐olefins. The resulting polymers exhibited rather broad molecular weight distributions and low syndiotacticities. In contrast to these initiators, the metallocene complexes (C₅H₅)₂Ni, (C₅Me₅)₂Ni, (Ind)₂Ni, and (Me₃SiC₅H₄)₂Ni provided narrower molecular weight distributions at 60 °C when these initiator were activated with MMAO. Half‐metallocene complexes such as (C₅H₅)NiCl(PPh₃), (C₅Me₅)NiCl(PPh₃), and (Ind)NiCl(PPh₃) produced poly(methyl methacrylate) (PMMA) with much narrower molecular weight distributions when the polymerization was carried out at 0 °C. Ni[1,3‐(CF₃)₂‐acac]₂ generated PMMA with high syndiotacticity. The NiR(acac)(PPh₃) complexes (R = Me or Et) revealed high selectivity in the polymerization of isoprene that produced 1,2‐/3,4‐polymer at 0 °C exclusively, whereas the polymerization at 60 °C resulted in the formation of cis‐1,4‐rich polymers. The polymerization of ethylene with Ni(1,3‐tBu₂‐acac)₂ and Ni[1,3‐(CF₃)₂‐acac]₂ generated oligo‐ethylene with moderate catalytic activity, whereas the reaction of ethylene with Ni(acac)₂/MMAO produced high molecular weight polyethylene. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4764–4775, 2000     

Novel neutral arylnickel(II) phosphine catalysts containing 2-oxazolinylphenolato N-O chelate ligands for ethylene oligomerization and propylene dimerization

A series of new neutral arylnickel(II) phosphine complexes 1 bearing 2-oxazolinylphenolato ligands [2-(4-R¹-5-R²-C₃H₂NO)-C₆H₄O]Ni(2-R⁴-4-R³-C₆H₃)(PPh₃) were synthesized by reactions of sodium salts of 2-(4,5-dihydro-2-oxazolyl)phenol derivatives with trans-Ni(Ar)(Cl)(PPh₃)₂ or by direct reactions of the ligands with trans-Ni(Ar)(Cl)(PPh₃)₂ in the presence of NEt₃. These neutral Ni(II) complexes 1 exhibited high activities and selectivities in ethylene oligomerization and propylene dimerization. The catalytic activities and the product distributions were dependent on the selection of various organoaluminum cocatalysts and phosphine scavenger (Ni(COD)₂). The effects of various reaction conditions on ethylene oligomerization were also examined. The highest activity of 5.51 × 10⁵ g oligomers/(mol Ni · h) and 83% selectivity of C₆ internal olefins were obtained in 1a/MAO catalytic system in ethylene oligomerization. The oligomers consisted mainly of lower carbon olefins in the range of C₄-C₈. Complexes 1 showed the moderate tolerance of polar additives in ethylene oligomerization. The highest activity of 1a/MAO in propylene dimerization reached to 1.32 × 10⁵ g oligomers/(mol Ni · h).     

Ein- und zweikernige Dinitrosylkomplexe von Molybdän und Wolfram. Die Kristallstrukturen von (PPh3Me)2[WCl4(NO)2], (PPh3Me)2[MoCl3(NO)2]2 und von (PPh3Me)2[WCl3(NO)2]2

Mono- and Binuclear Dinitrosyl Complexes of Molybdenum and Tungsten. Crystal Structures of (PPh₃Me)₂[WCl₄(NO)₂], (PPh₃Me)₂[MoCl₃(NO)₂]₂, and (PPh₃Me)₂[WCl₃(NO)₂]₂ The complexes (PPh₃Me)₂[MCl₄(NO)₂] (M = Mo, W), and (PPh₃Me)₂[MCl₃(NO)₂]₂, respectively, are prepared by reactions of the polymeric compounds MCl₂(NO)₂ with triphenylmethylphosphonium chloride in CH₂Cl₂, forming green crystals. According to the IR spectra the nitrosyl groups are in cis-position in all cases. The tungsten compounds as well as (PPh₃Me)₂[MoCl₃(NO)₂]₂ were characterized by structure determinations with X-ray methods. (PPh₃Me)₂[WCl₄(NO)₂]: space group C2/c, Z = 4. a = 1874, b = 1046, c = 2263 pm, β = 119.99°. Structure determination with 3492 independent reflexions, R = 0.057. The compound consists of PPh₃Me^⊕ ions, and anions [WCl₄(NO)₂]^2? with the nitrosyl groups in cis-position (symmetry C_2v). (PPh₃Me)₂[WCl₃(NO)₂]₂: Space group C2/c, Z = 4. Structure determination with 2947 independent reflexions, R = 0.059. (PPH₃Me)₂[MoCl₃(NO)₂]₂: Space group P1 , Z = 1. a = 989, b = 1134, c = 1186 pm; α = 63.25°, β = 80.69°, γ = 69.94°. Structure determination with 3326 independent reflexions, R = 0.046. The compounds consist of PPh₃Me^⊕ ions, and centrosymmetric anions [MCl₃(NO)₂]₂^2?, in which the metal atoms are associated via MCl₂M bridges of slightly different lengths. One of the NO groups is in an axial position, the other one in equatorial position (symmetry C_2h).     

Catalytic behavior tuning via structural modifications of silylated-diphosphine Ni(II) complexes for ethylene selective dimerization

The methylene spacers and an uncoordinated diphenylphosphine moiety in the scaffold of the CH₃Si(CH₂)_n(PPh₂)₃ and Si(CH₂PPh₂)₄-type silylated diphosphine Ni(II) complex systems have a marked impact on their catalytic performance in selective ethylene dimerization. Ni(II)-based precatalyst 1 , bearing two methylene spacers in its framework, exhibited the highest catalytic activity of 1.29 × 10⁸ g (mol_Ni)^-1 h^-1, while precatalyst 3 , with three methylene spacers, affords the highest product selectivity (88%) toward the C₄ fraction. Crystallographic investigations revealed that the precatalyst 3 adopts the mononuclear bidentate binding mode and the steric constraints of its uncoordinated diphenylphosphine moiety may successfully tailor the catalytic environment of the catalyst. The precatalyst 4 may form a dinuclear complex and exhibits high catalytic activity by changing the ligand/Ni molar ratio. The high C₄ selectivity of precatalyst 3 has been rationalized by density functional theory (DFT) calculations and found to be consistent with the experimental results. The study also revealed that designing new systems of Ni(II)-based complexes and their systematic modifications may further provide potential and industrially viable catalyst systems for selective ethylene oligomerization.     

New Half‐Metallocene Catalysts Generating Polyethylene with Bimodal Molecular Weight Distribution and Syndiotactic Polystyrene

A new type of half‐metallocene catalyst for the polymerization of ethylene and styrene, Cp*M((O)₃O₉Si₇(c‐C₅H₉)₇) (M = Ti ( 1) ; Zr ( 2 )), is prepared by the reaction of (HO)₃O₉Si₇(c‐C₅H₉)₇ with Cp*MCl₃ in the presence of triethylamine. Complex 1 is stable to heat and air, but its heavier congener 2 is slightly air‐sensitive. The catalytic systems 1 /MMAO and 2 /MMAO, in which MMAO is modified methylaluminoxane, show good activities in ethylene polymerization, with that of 2 /MMAO greater than that of 1 /MMAO. Polyethylenes with bimodal molecular weight distributions were obtained. In addition, the catalytic system 1 /MMAO shows fairly good activities for the syndiospecific polymerization of styrene.     

Komplexe mit kohlenstoffsulfiden und -seleniden als liganden: XIII. Reaktionen der metall-basen C5H5M(PR3)2 und C5H5M(PR3)L (M = Co,Rh) mit CSSe und CSe2: synthese und eigenschaften von cyclopentadienylcobalt- und rhodium- komplexen mit CS,CSe, CSSe,CSe2, CSSe22−, CSe32−, C2S2Se22−- und C2Se42−- als liganden

C₅H₅Co(PMe₃)₂ (I) reacts with CSSe to give C₅H₅Co(η²-CSSe)PMe₃ (IV) and C₅H₅Co(CS)PMe₃ (V). The thiocarbonyl complex V is formed in an almost quantitative yield by Se abstraction from IV and PPh₃. The corresponding compounds C₅H₅Co(CS)PMe₂Ph (VII) and C₅H₅Co(CS)[P(OMe)₃] (VIII) are obtained as the main products directly from CSSe and C₅H₅Co(PMe₂Ph)₂ or C₅H₅Co[P(OMe)₃]₂. In the reaction of C₅H₅Co(PR₃)₂ (PR₃ = PMe₃, PMe₂Ph) with CSe₂, the carbon diselenide complexes C₅H₅Co(η²-CSe₂)PMe₃ (XI) and C₅H₅Co(η²-CSe₂)PMe₂Ph (XIV) are formed. XI reacts with PPh₃ to give C₅H₅Co(CSe)PMe₃ (XII). Cyclopentadienylcobalt compounds containing CSSe₂^2?, CSe₃^2? and C₂Se₄^2? as ligands are isolated as side products in the; reactions of C₅H₅Co(PR₃)₂ and C₅H₅Co(CO)PR₃ (PR₃ = PMe₃, PMe₂Ph) with CSSe and CSe₂, respectively. Displacement of ethylene from C₅H₅Rh(C₂H₄)PMe₃ by CSSe yields the complex C₅H₅Rh(η²-CSSe)PMe₃ (XVIII) which reacts with PPh₃ to give C₅H₅Rh(CS)PMe₃ (XIX) and with excess CSSe to give C₅H₅RhC₂S₂Se₂(PMe₃) (XX). Besides small amounts of C₅H₅Rh(η²CSSe)PMe₂Ph (XXI), the corresponding metallaheterocycle C₅H₅RhC₂S₂Se₂(PMe₂Ph) (XXII) is formed as the main product from C₅H₅Rh(C₂H₄)PMe₂Ph and CSSe.     

Structural and Photophysical Study on Heterobimetallic Complexes with d8–d10 Interactions Supported by Carborane Ligands: Theoretical Analysis of the Emissive Behaviour

Heterobimetallic complexes of formula [M{(PPh₂)₂C₂B₉H₁₀}(S₂C₂B₁₀H₁₀)M′(PPh₃)] (M=Pd, Pt; M′=Au, Ag, Cu) and [Ni{(PPh₂)₂C₂B₉H₁₀}(S₂C₂B₁₀H₁₀)Au(PPh₃)] were obtained from the reaction of [M{(PPh₂)₂C₂B₁₀H₁₀}(S₂C₂B₁₀H₁₀)] (M=Pd, Pt) with [M′(PPh₃)]⁺ (M′=Au, Ag, Cu) or by one‐pot synthesis from [(SH)₂C₂B₁₀H₁₀], (PPh₂)₂C₂B₁₀H₁₀, NiCl₂ ? 6 H₂O, and [Au(PPh₃)]⁺. They display d⁸–d¹⁰ intermetallic interactions and emit red light in the solid state at 77 K. Theoretical studies on [M{(PPh₂)₂C₂B₉H₁₀}(S₂C₂B₁₀H₁₀)Au(PPh₃)] (M=Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)‐to‐“P₂‐M‐S₂” (ML′) charge‐transfer (LML′CT) transitions for M=Pt and to metal (M)‐to‐“P₂‐M‐S₂” (ML′) charge‐transfer (MML′CT) transitions for M=Ni, Pd.     

The preperation and coordination properties of 1,4-diaza-3-methylbutadiene-2-ylpalladium(II) complexes with different substituents on the imino nitrogen atoms

The complexes trans-[PdCl{$\text{C(=NR)C}$(ME)=NR'} (PPh₃)₂] (R=C₆H₁₁,p-C₆H₄OMe; R$\text{.}\text{?}$=p-C₆H₄OMe, Me) containing a σ-bonded 1,4-diaza-3-menthyl-butadiene-2-yl group with different substituents on the nitrogen atoms have been prepared by two routes. The first involves initial methylation of the mixed isonitrile complex [PdCl₂(CNR)(CNR')]by HgMe₂, followed by reaction with PPh₃ ($\text{Pd}\text{PPh}{}_3$molar ratio $\text{1}\text{2}$). The second method involves condensation of primary aliphatic amines with the carbonyl group of the 1-azabut-1-en-3-one-2-yl moiety of the complex trans-[PdCl{$\text{C(=NR)C}$(Me) = 0} (PPh₃)₂]. The 1,4-diaza-3-methylbutadiene-2-yl derivatives act through their imino nitrogen atoms as chelating ligands towards anhydrous metal chlorides MCl₂ (M = Co, Ni, Cu, Zn). Magnetic moment measurements and the far-infrared and electronic spectra of these adducts indicate an essentially pseudo-tetrahedral configuration at M in the solid and in solution. With the ZnCl₂ adducts, the ¹H NMR pattern for the phenyl protons of the p-methoxyphenyl N-substituents dependss upon the position of the substituent i the 1,4-diazabutadiene chain.     

Synthesen und Charakterisierungen der ersten Tris‐ und Tetrakis(trifluormethyl)palladate(II) und ‐platinate(II), [M(CF3)3(PPh3)]— und [M(CF3)4]2— (M = Pd,Pt)

Syntheses and Characterizations of the First Tris and Tetrakis(trifluoromethyl) Palladates(II) and Platinates(II), [M(CF₃)₃(PPh₃)]^— and [M(CF₃)₄]^2— (M = Pd, Pt) Tris(trifluoromethyl)(triphenylphosphino)palladate(II) and platinate(II), [M(CF₃)₃PPh₃]^—, and the tetrakis(trifluoromethyl)metallates, [M(CF₃)₄]^2— (M = Pd, Pt), are prepared from the reactions of [MCl₂(PPh₃)₂] and Me₃SiCF₃ / [Me₄N]F or [I(CF₃)₂]^— salts in good yields. [Me₄N][M(CF₃)₃(PPh₃)] crystallize isotypically in the orthorhombic space group Pnma (no. 62) with Z = 4. The NMR spectra of the new compounds are described.     

[Au(C6F5)3(PPh2H)]: A Precursor for the Synthesis of Gold(III) Phosphide Complexes

The covalent radius of Au ^I is about 0.07 Å smaller than that of Ag^I. This was determined from the crystal structures of the isostructural complexes [N(PPh₃)][{Au(C₆F₅)₃(μ-PPh₂)}₂M] (M=Au (structure shown in the picture), Ag). These mixed Au^III–M phosphides were synthesized from [Au(C₆F₅)₃(PPh₂H)], the first gold complex to contain a secondary phosphane.     

Large‐ring P/O chelate nickel complex catalyzed oligomerization of ethylene to linear α‐olefins

1,1‐(Bicyclononyl‐9‐phosphino)hendecanoic acid and potassium 1,1‐(biscyclohexylphosphino)­hendecylate were synthesized. A model nickel complex [η³−C₈H₁₃]Ni[(C₈H₁₄)P(CH₂)₁₀COO] containing a 14‐membered chelate ring was also synthesized. The catalytic activity of this large chelate ring nickel complex for the oligomerization of ethylene was studied and compared with that of six‐membered ring chelate nickel complexes. The influence of the chelate ring was rationalized in terms of intramolecular rotation. The 14‐membered ring P/O chelate nickel complex was shown to have efficient catalytic activity for the oligomerization of ethylene to α‐olefins. Copyright © 2000 John Wiley & Sons, Ltd.     

A Tandem Catalytic System for the Synthesis of Ethylene–Hex‐1‐ene Copolymers from Ethylene Stock

Summary: A tandem catalytic system, composed of (η⁵‐C₅H₄CMe₂C₆H₅)TiCl₃ ( 1 )/MMAO (modified methyl aluminoxane) and [(η⁵‐C₅Me₄)SiMe₂(tBuN)]TiCl₂ ( 2 )/MMAO, was applied for the synthesis of ethylene–hex‐1‐ene copolymers with ethylene as the only monomer stock. During the reaction, 1 /MMAO trimerized ethylene to hex‐1‐ene, while 2 /MMAO copolymerized ethylene with the in situ produced hex‐1‐ene to poly(ethylene–hex‐1‐ene). By changing the catalyst ratio and reaction conditions, a series of copolymer grades with different hex‐1‐ene fractions at high purity were effectively produced.

The overall strategy of the tandem 1 / 2 /MMAO catalytic system.     

Borane Activators for Late‐Transition Metal Catalysts in Norbornene Polymerization

Nickel(II) and palladium(II) complexes of the general type [MCl₂{Ph₂P(CH₂)_nPPh₂}] with n = 2, 3 and M = Ni ( 2 , 3 ), Pd ( 4 , 5 ) have been utilized as catalysts for the polymerization reaction of norbornene. It was found that the use of B(C₆F₅)₃/triethylaluminium (TEA) in comparison to methylaluminoxane as an activator towards complexes 2 , 3 and 5 gave comparable polymerization activities, and the system 4 /B(C₆F₅)₃/TEA even led to an extremely high polymerization activity of 10⁷ g_polymer/mol_metal· h.     

Platinum group metal functionalized phosphine complexes. Part 2. Phosphinoamide rhodium(I), iridium(I), palladium(II) and platinum(II) complexes

Summary Rhodium(I), iridium(I), palladium(II) and platinum(II) complexes of the phosphinoamide ligands, Ph₂PCH₂CONHR (R = H, HDPA; Me, MDPA; Ph, PDPA) were prepared and characterized by using conductivity data, i.r., ¹H and ³¹P(H) n.m.r. spectral data. Reaction of the ligands with MCl(PPh₃)₃ and MCl(CO)(PPh₃)₂ (M = Rh, Ir) in CH₂Cl₂ under reflux lead to the formation of MCl(PPh₃)₂ [Ph₂PCH₂C(O)NHR] and MCl(CO)(PPh₃)[Ph₂PCH₂–C(O)HNR] respectively. The reaction of either K₂MCl₄ or cis-MCl₂(PPh₃)₂ affords complexes of the type cis-MCl₂[Ph₂PCH₂C(O)NHR]₂ (M = Pd, Pt). A similar product results even from the reaction of phosphinoamides with cis-platin. Possible structures are proposed for the complexes based on their physicochemical data     

Redox properties of (RC2R')Co2(CO)6-nLn and reactivity of (RC2R')Co2(CO)6-nLn towards PPh3[LPPh3, P(OEt)3]

Cyclic voltammetric studies of clusters (C₅H₅-C₂C₆ H₄-R-p)Co₂(CO)6-n L_n[n=0,2; L=PPh₃, P(OEt)₃] and (RCH₂C)₂Co₂(CO₄) (PPh₃)₂ on Pt electrode are described. The primary reduction (0 / ?1) and oxidation (+ 1 / 0) steps are considered as a mono-electron process for all clusters. For the clusters (C₅H₅C₂C₆H₄-R-p)Co₂(CO)₆, a good linear relation between reduction potential E_p^red and Hammett constant σ_p of R in the clusters is found. For the clusters (RC₂R')Co₂(CO)₄L₂, their radical anions are extremely unstable at room temperature and fragment into a series of mononuclear species, one of which is (RC₂R')Co(CO)₂PPh₃. The reaction of radical anions of (RC₂R')Co₂(CO)_6–n (PPh₃)_n(n=0,2) with PPh₃ also produces mononuclear species (RC₂R')Co(CO)₂PPh₃ which has been detected by means of cyclic voltammetry and ESR. The influence of R on redox properties of clusters is discussed.     

NNNO-Heteroscorpionate nickel (II) and cobalt (II) complexes for ethylene oligomerization: the unprecedented formation of odd carbon number olefins

The unprecedented observation of odd carbon number olefins is reported during nickel- catalyzed ethylene oligomerization. Two complexes based on Co (II) and Ni (II) with novel tetradentate heteroscorpionate ligand have been synthesized and fully characterized. These complexes showed the ability to oligomerize ethylene upon activation with various organoaluminum compounds (Et₂AlCl, Et₃Al₂Cl₃, EtAlCl₂, MMAO). Ni (II) based catalytic systems were sufficiently more active (up to 1900 kg·mol (Ni)⁻¹·h⁻¹·atm⁻¹) than Co (II) analogs and have been found to be strongly dependent on the activator composition. The use of PPh₃ as an additive to catalytic systems resulted in the increase of activity up to 4,150 kg·mol (Ni)⁻¹·h⁻¹·atm⁻¹ and in the alteration of selectivity. All Ni (II) based systems activated with EtAlCl₂ produce up to 5 mol. % of odd carbon number olefins; two probable mechanisms for their formation are suggested – metathesis and β-alkyl elimination.