Phenoxide Ligands Research Articles

Synthesis of (Arylimido)niobium(V) Bis(diethylamide) Complexes Containing Phenoxide Ligands

AbstractReaction of (arylimido)niobium(V) tris(diethylamide) complexes, Nb(NAr)(NEt2)3, prepared by treating Nb(NAr)Cl3(dme) (dme=1,2‐dimethoxyethane) with 3.0 equiv. of LiNEt2, with 1.0 equiv. of phenol afforded the corresponding phenoxide complexes, Nb(NAr)(NEt2)2(O‐2,6‐R2C6H3) [1 a–c, 2 a–c; Ar=2,6‐Me2C6H3 (1) 2,6‐iPr2C6H3 (2); R=tBu (a), iPr (b), Me (c)], which were identified by NMR spectroscopy, elemental analysis and the structures for 2 b, c were determined by X‐ray crystallographic analysis.

Electronic Structure and Transformation of Dinitrosyl Iron Complexes (DNICs) Regulated by Redox Non-Innocent Imino-Substituted Phenoxide Ligand.

The coupled NO-vibrational peaks [IR νNO 1775 s, 1716 vs, 1668 vs cm-1 (THF)] between two adjacent [Fe(NO)2] groups implicate the electron delocalization nature of the singly O-phenoxide-bridged dinuclear dinitrosyliron complex (DNIC) [Fe(NO)2(μ-ON2Me)Fe(NO)2] (1). Electronic interplay between [Fe(NO)2] units and [ON2Me]- ligand in DNIC 1 rationalizes that "hard" O-phenoxide moiety polarizes iron center(s) of [Fe(NO)2] unit(s) to enforce a "constrained" π-conjugation system acting as an electron reservoir to bestow the spin-frustrated {Fe(NO)2}9-{Fe(NO)2}9-[·ON2Me]2- electron configuration (Stotal = 1/2). This system plays a crucial role in facilitating the ligand-based redox interconversion, working in harmony to control the storage and redox-triggered transport of the [Fe(NO)2]10 unit, while preserving the {Fe(NO)2}9 core in DNICs {Fe(NO)2}9-[·ON2Me]2- [K-18-crown-6-ether)][(ON2Me)Fe(NO)2] (2) and {Fe(NO)2}9-[·ON2Me] [(ON2Me)Fe(NO)2][PF6] (3). Electrochemical studies suggest that the redox interconversion among [{Fe(NO)2}9-[·ON2Me]2-] DNIC 3 ↔ [{Fe(NO)2}9-[ON2Me]-] ↔ [{Fe(NO)2}9-[·ON2Me]] DNIC 2 are kinetically feasible, corroborated by the redox shuttle between O-bridged dimerized [(μ-ONMe)2Fe2(NO)4] (4) and [K-18-crown-6-ether)][(ONMe)Fe(NO)2] (5). In parallel with this finding, the electronic structures of [{Fe(NO)2}9-{Fe(NO)2}9-[·ON2Me]2-] DNIC 1, [{Fe(NO)2}9-[·ON2Me]2-] DNIC 2, [{Fe(NO)2}9-[·ON2Me]] DNIC 3, [{Fe(NO)2}9-[ONMe]-]2 DNIC 4, and [{Fe(NO)2}9-[·ONMe]2-] DNIC 5 are evidenced by EPR, SQUID, and Fe K-edge pre-edge analyses, respectively.

Synthesis of ethylene copolymers with 2-allylphenol by using half-titanocene catalysts containing SiEt3-, SiiPr3-substituted phenoxide ligands, Cp*TiCl2(O-2,6-iPr2-4-SiR3-C6H2) (R = Et, iPr)

Efficient synthesis of ethylene copolymers with 2-allylphenol has been achieved by using the Cp*TiCl2(O-2,6-iPr2-SiEt3-C6H2)–MAO catalyst system.

Mn(II), Fe(II), and Co(II) Aryloxides: Steric and Dispersion Effects and the Thermal Rearrangement of a Cobalt Aryloxide to a Co(II) Semiquinone Complex.

A series of Mn(II), Fe(II), and Co(II) bisaryloxide dimers ([M(OC6H2-2,4,6-Cy3)2]2 {M = Mn (1), Fe (2), and Co (3)} were synthesized by the addition of 2,4,6-tricyclohexylphenol (HOC6H2-2,4,6-Cy3) to the silyl amido dimers [M(N(SiMe3)2)2]2 (M = Mn, Fe, Co; Cy = cyclohexyl). An unexpected and unique Co(II) phenoxide derivative (4), [Co(OC6H2-2,4,6-Cy3)(O2C6H-3,5,6-Cy3)]2, was obtained via ligand rearrangement of 3 at ca. 180 °C. This yielded 4 in which there are two unchanged, bridging phenoxide ligands as well as a terminal bidentate semiquinone ligand bound to each cobalt. Complexes 1 and 2 did not undergo such a rearrangement under the same conditions; both are thermally stable to temperatures exceeding 250 °C and feature numerous short-contact (<2.5 Å) H···H interactions consistent with the presence of dispersion stabilization. Use of the aryloxide ligand -OC6H3-2,6-Pri2 (Pri = isopropyl), which is sterically similar to -OC6H2-2,4,6-Cy3 but produces fewer close H···H interactions, gave the trimeric species [M(OC6H3-2,6-Pri2)2]3 {M = Fe (5) or Co (6)} which feature a linear array of three metal atoms bridged by aryloxides. The higher association number in 5 and 6 in comparison to that of 1-3 is due to the lower dispersion energy donor properties of the -OC6H3-2,6-Pri2 ligand and the lower stabilization it produces.

Synthesis of Ethylene/Isoprene Copolymers Containing Cyclopentane/Cyclohexane Units as Unique Elastomers by Half-Titanocene Catalysts

Ethylene (E) copolymers with isoprene (IP) possessing higher glass-transition temperatures (Tg values, −7.1 to 29.2 °C) than those prepared by the reported catalysts (Tg below −18 °C) have been prepared in the copolymerization by using half-titanocene catalysts containing phenoxide ligand, Cp′TiCl2(O-2,6-iPr2-4-R-C6H2) [Cp′ = C5Me5 (Cp*), R = H (1), SiEt3 (2)]. Their microstructural analysis by NMR spectra revealed that the copolymers contained cyclopentane (major) and cyclohexane units, formed by cyclization after IP and subsequent ethylene insertions, in addition to 1,4- and 3,4-IP inserted units observed as major units in those prepared by reported catalysts. The 1,2,4-Me3C5H2 analogue (R = H) showed better IP incorporation, but the resulting E/IP copolymers possessed rather low Tg values compared to those prepared by 1,2 due to less cyclopentane unit in the microstructure. The Tg value in the E/IP copolymer increased upon the increase of the IP content, and the degree was dependent upon the catalyst employed. Due to their unique microstructure, the resulting E/IP copolymers prepared by 1,2–MAO catalyst systems exhibit promising tensile and elastic properties. The tensile strength initially decreased with an increase in the IP content along with an increase of the elongation at break (up to 600%, IP 3.3–15.6 mol %) and then increased gradually with further increase in the IP contents (IP 18.1–21.5 mol %); the elongation at break then decreased with preserving the tensile strength along with the observation of the yield stress.

Selective Stepwise Arylation of Unprotected Peptides by PtIV Complexes.

LPtIVF(Aryl) complexes bearing a bulky bidentate 2‐[bis(adamant‐1‐yl)phosphino]phenoxide ligand (L) demonstrate excellent reactivity and selectivity in the arylation of X−H (X=S, N) bonds of amino acid residues in unprotected peptides under mild, including aqueous, conditions. Stepwise addition of these complexes allowed a convenient one‐pot introduction of different aromatic groups in the X−H bonds of Cys and N terminus. PtIV reagents can also be used to further arylate N−H bonds in Lys and Trp providing access to peptides bearing multiple aromatic groups.

Selective Stepwise Arylation of Unprotected Peptides by Pt IV Complexes

LPtIVF(Aryl) complexes bearing a bulky bidentate 2-[bis(adamant-1-yl)phosphino]phenoxide ligand (L) demonstrate excellent reactivity and selectivity in the arylation of X−H (X=S, N) bonds of amino acid residues in unprotected peptides under mild, including aqueous, conditions. Stepwise addition of these complexes allowed a convenient one-pot introduction of different aromatic groups in the X−H bonds of Cys and N terminus. PtIV reagents can also be used to further arylate N−H bonds in Lys and Trp providing access to peptides bearing multiple aromatic groups.

Benzoxazole phenoxide ligand supported group IV catalysts and their application for the ring‐opening polymerization of rac‐lactide and ε‐caprolactone

Monomeric titanium [C48H62N2O6Ti] (1) and zirconium [C48H62N2O6Zr] (2) complexes were synthesized by combining the monoanionic salicylbenzoxazole pro‐ligand 2‐(5‐X‐benzoxazol‐2‐yl)‐6‐R1‐4‐R2‐phenol, LH (R1, R2, X = tBu, tBu, H, respectively) with Ti(OiPr)4 or Zr(OiPr)4∙(iPrOH) in a 2:1 stoichiometric ratio. Controlled hydrolysis of the monomeric Ti complex with deionized water yielded a new unusual hexanuclear titanium complex [C126H144N6O21Ti6] (3). In addition, the cage formed in this complex 3 was surrounded by all‐oxygen and penta‐coordinated Ti(IV) atoms, which leads to an hexanuclear drum‐shaped Ti complex 3 with a trigonal‐bipyramidal geometry at the metal center. The catalytic activity of these complexes toward ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) and rac‐lactide (rac‐LA) was studied. All these complexes showed moderate to good catalytic activity without using any co‐catalyst additives. Single‐site zirconium alkoxide 2 showed the best catalytic activity and was able to convert 400 units of ε‐CL or rac‐LA into the polymer product in high yield (≥90%) within 1 hour under solvent‐free conditions. The obtained polymers showed good control in molecular weight (Mn = 46.2–6.3 kg/mol) and molecular weight distributions (MWD's = 1.37–1.15). The polymerization of rac‐LA by 2 yielded iso‐enriched polylactide (Pm = 0.60).

Aryl C(sp2)-X Coupling (X = C, N, O, Cl) and Facile Control of N-Mono- and N,N-Diarylation of Primary Alkylamines at a Pt(IV) Center.

We present the first example of an unprecedented and fast aryl C(sp2)–X reductive elimination from a series of isolated Pt(IV) aryl complexes (Ar = p-FC6H4) LPtIVF(py)(Ar)X (X = CN, Cl, 4-OC6H4NO2) and LPtIVF2(Ar)(HX) (X = NHAlk; Alk = n-Bu, PhCH2, cyclo-C6H11, t-Bu, cyclopropylmethyl) bearing a bulky bidentate 2-[bis(adamant-1-yl)phosphino]phenoxide ligand (L). The C(sp2)–X reductive elimination reactions of all isolated Pt(IV) complexes follow first-order kinetics and were modeled using density functional theory (DFT) calculations. When a difluoro complex LPtIVF2(Ar)(py) is treated with TMS–X (TMS = trimethylsilyl; X= NMe2, SPh, OPh, CCPh) it also gives the corresponding products of the Ar–X coupling but without observable LPtIVF(py)(Ar)X intermediates. Remarkably, the LPtIVF2(Ar)(HX) complexes with alkylamine ligands (HX = NH2Alk) form selectively either mono- (ArNHAlk) or diarylated (Ar2NAlk) products in the presence or absence of an added Et3N, respectively. This method allows for a one-pot preparation of diarylalkylamine bearing different aryl groups. These findings were also applied in unprecedented mono- and di-N-arylation of amino acid derivatives (lysine and tryptophan) under very mild conditions.

Synthesis and Structural Analysis of Four Coordinate (Arylimido)niobium(V) Dimethyl Complexes Containing Phenoxide Ligand: MAO-Free Ethylene Polymerization by the Cationic Nb(V)–Methyl Complex

Four coordinate (arylimido)niobium(V) dimethyl complexes containing 2,6-di-tert-butylphenoxy ligand, Nb(NAr)Me2(O-2,6-tBu2C6H3) [Ar = 2,6-iPr2C6H3 (5a), 2,6-Me2C6H3 (5b), 2-MeC6H4 (5c)], were prepa...

Coligand modulated oxidative O-demethylation of a methyl ether appended tetradentate N-ligand in Co(ii) complexes.

Two Co(ii) complexes of the formula CoLOMeX2 (X = Cl- (1a); X = I- (1b)), where LOMe is 2-methoxy-N,N-bis(pyridin-2-ylmethyl) aniline, were synthesized and their structure, spectra and reactivity were studied. Upon oxidation of 1a and 1b, the ligand LOMe undergoes demethylation at the metal centre resulting in the formation of Co(iii) complexes with modified phenoxide ligands. This is the very first example of oxidative O-demethylation reported at a Co(ii) centre. The oxidative behaviour exhibits a striking dependence on the nature of coligands coordinated to the metal centre. The Co(ii) complex 1a with stronger chloro coligands requires a strong oxidising agent like t-BuOOH for oxidative demethylation and the subsequent formation of a mononuclear Co(iii) complex with a demethylated ligand, CoLO-Cl2 (2). On the other hand, complex 1b with weaker iodo coligands undergoes oxidation in the presence of the weak oxidant O2 to form a dihydroxo bridged binuclear Co(iii) complex [Co2(LO-)2(OH)2]2+ (3) with modified phenoxide ligands. The oxidation of 1b to 3 is monitored and the intermediate Co(ii) iodo aqua complex [CoLOMeI(H2O)]+ and Co(ii) diaqua complex [CoLOMe(H2O)2]2+ are isolated and characterised.

Synthesis, Structure, and Luminescence Properties of Boron Complex with 4-Bromo-2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenoxide Ligand

A boron complex with 4-bromo-2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenoxide ligand has been synthesized, and its photoluminescence properties in solution and in the solid phase have been examined. The structure of the complex has been determined by X-ray analysis. Non-classical intermolecular interaction (halogen bond) between the bromine and fluorine atoms has been detected in the crystal structure of the complex.

XAS Analysis of Reactions of (Arylimido)vanadium(V) Dichloride Complexes Containing Anionic NHC That Contains a Weakly Coordinating B(C6F5)3 Moiety (WCA-NHC) or Phenoxide Ligands with Al Alkyls: A Potential Ethylene Polymerization Catalyst with WCA-NHC Ligands.

(Arylimido)vanadium(V) dichloride complexes containing anionic N-heterocyclic carbene (NHC) ligands that contain weakly coordinating B(C6F5)3 moieties (WCA-NHC) of the type [V(NAr)Cl2(WCA-NHC-Ar′)] (5, Ar = 2,6-Me2C6H3, Ar′ = 2,6-iPr2C6H3) showed significant catalytic activity for ethylene polymerization in the presence of Al cocatalysts (MAO and AliBu3); the activity by the 5–MAO catalyst (19 500 kg-PE/mol-V·h; TOF 11 600 min–1) is the highest among those reported using the other (imido)vanadium(V) complexes in the presence of MAO, and the 5–AliBu3 catalyst showed higher activity (66 000 kg-PE/mol-V·h; TOF 39 200 min–1). The V K-edge X-ray absorption near-edge structure (XANES) analyses (in toluene) strongly suggest the formation of certain vanadium(III) species by reduction with AliBu3 accompanying structural changes; the EXAFS analysis suggests the presence of the arylimido ligand and one V–Cl bond (2.34 ± 0.04 Å), which is longer than those [2.1901(8)–2.2462(8) Å] in the reported (imido)vanadium(V) complexes. The XANES analysis of [V(NAr)Cl2(OAr)] strongly suggests the formation of the other vanadium(III) species by reduction with Me2AlCl or Et2AlCl, and the EXAFS analysis suggests the presence of the arylimido ligand and two V–Cl bonds (2.45 ± 0.03 Å). The XANES spectra showed no significant changes in both the pre-edge peak(s) and the edge peak when these complexes were treated with MAO, suggesting that the basic geometry and the high oxidation state were preserved under these conditions.

Crystal structure of a binuclear mixed-valence ytterbium complex containing a 2-anthracene-substituted phenoxide ligand.

Reaction of 2-(anthracen-9-yl)phenol (HOPhAn, 1) with divalent Yb[N(SiMe3)2]2·2THF in THF-toluene mixtures affords the mixed-valence YbII-YbIII dimer {[2-(anthracen-9-yl)phenolato-κO]bis-(tetra-hydro-furan)-ytterbium(III)}-tris-[μ-2-(anthracen-9-yl)phenolato]-κ4 O:O;κO:1,2-η,κO-{[2-(anthracen-9-yl)phenolato-κO]ytterbium(II)} toluene tris-olvate, [Yb2(C20H13O)5(C4H8O)2]·3C7H7 or [YbIII(THF)2(OPhAn)](μ-OPhAn)3[YbII(OPhAn)]·3C7H7 (2), as the major product. It crystallized as a toluene tris-olvate. The Yb-O bond lengths in the crystal structure of this dimer clearly identify the YbII and YbIII centres. Inter-estingly, the formally four-coordinate YbII centre shows a close contact with one anthracene C-C bond of a bridging OPhAn ligand, bringing the formal coordination number to five.

Immortal Ring Opening Polymerization of ε-caprolactone and rac-lactide by magnesium precatalysts bearing sterically congested phenoxide ligands

This report describes the synthesis of a series of magnesium complexes bearing sterically congested phenoxide ligands and their catalytic performances in initiating immortal Ring Opening Polymerization of ε-caprolactone and rac-lactide. The magnesium complexes Mg1-Mg3 were obtained in high yields, by treating bulky phenoxide ligands with half equivalents of Mg(n-Bu)2 in THF (Mg1: Mg(O-2,6-Ph2CH-C6H2-4-Me)2(THF)2; Mg2: Mg(O-2,6-Ph2CH-C6H2-4-OMe)2(THF)2; Mg3: Mg(O-2-Ph2CH-C6H2-4,6-tBu2)2(THF)2), and well-characterized by NMR spectrum analysis. The molecular structures of Mg2, Mg3 were further determined by single crystal X-ray diffractions. In combination with excess of benzhydrol, these complexes could catalyze immortal Ring Opening Polymerization (ROP) of ε-caprolactone and rac-lactide, and benzhydrol served as co-initiator and chain transfer agents simultaneously, which afforded polymer esters with well-controlled molecular weights and narrow molecular weight distributions. End-functionalized polyester could be also accessed if functionalized benzhydrols were employed as chain transfer agents.

Lanthanide bis(borohydride) complexes coordinated by tetradentate phenoxide ligand: Synthesis, structure, and catalytic activity in ring-opening polymerization of rac-lactide and ε-caprolactone

New lanthanide bis(borohydride) complexes coordinated by monoanionic tetradentate phenoxide ligand [(C5H4NCH2)2NCH2(3,5-tBu2C6H2O)]Ln(BH4)2 [Ln = Y (1), Nd (2), Sm (3)] were synthesized by the reactions of Ln(BH4)3(THF)3 with an equimolar amount of the lithium phenoxide [(C5H4NCH2)2NCH2(3,5-tBu2C6H2O)Li] in THF at 60 °C. The complexes were isolated after recrystallization from toluene in 75, 64, and 69% yields, respectively. X-ray analysis revealed that in 1 the phenoxide ligand is tetradentate, while two borohydride groups are coordinated to the Y3+ ion in a κ3-fashion. Compounds 1–3 initiate ring-opening polymerization (ROP) of ɛ-caprolactone (ɛ-CL) and racemic lactide (rac-LA) in toluene at 25 °C. The obtained polylactides are characterized by atactic structures Pr = 0.54–0.58, and rather narrow polydispersities (Mw/Mn = 1.1–1.5). For ɛ-caprolactone polymerization, the resulting polymers have moderate polydispersities (Mw/Mn = 1.4–2.4) and molecular weights (6.2–54.1·103).

Crystal Structure of the Octahedral Rhenium Cluster Complex (Bu4N)4[Re6S8(OC6H4-p-NO2)6

A cluster complex with the composition (Bu4N)4[Re6S8(CC6H4-p-NC2)6] having terminal phenoxide ligands is obtained by the reaction of (Bu4N)4[Re6S8Cl6] with silver p-nitrophenolate. The compound crystallizes in the orthorhombic space group Pccn with the following unit cell parameters: a = 19.507(2) A, b = 31.645(3) A, c = 19.237(2) A, V = 19.237(2) A3, Z = 4, dcalc = 1.774 g/cm3.

Crystal structure of the octahedral rhenium cluster complex (Bu4N)4[Re6S8(OC6H4-p-NO2)6

A cluster complex with the composition (Bu4N)4[Re6S8(OC6H4-p-NO2)6] having terminal phenoxide ligands is obtained by the reaction of (Bu4N)4[Re6S8Cl6] with silver p-nitrophenolate. The compound crystallizes in the orthorhombic space group Pccn with the following unit cell parameters: a = 19.507(2), b = 31.645(3), c = 19.237(2) Å, V = 19.237(2) Å3, Z = 4, dcalc = 1.774 g/cm3.

Heterobimetallic aluminate derivatives with bulky phenoxide ligands: a catalyst for selective vinyl polymerization.

New aluminium-alkali metal heterometallic compounds using the bulky ligand OAr = 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide have been synthesized and characterized. The species obtained, [MAlMe3(OAr)] (M = Li(2a), Na(2b), K(2c)) and [MAlMe2(OAr)2] (M = Li(3a), Na(3b), K(3c)), include some of the few heterobimetallic examples of aluminate complexes with O-donor ligands described so far. Their activity in polymerization towards a difunctional monomer, such as Glycidyl Methacrylate (GMA), was evaluated. The compounds were revealed to be able to polymerize the acrylate groups via vinyl polymerization. Interestingly, the homometallic counterparts [AlXMe(OAr)] (X = Cl, Me), previously described by us, are very active in ROP processes of GMA. The combined polymerization process using both catalysts has also been explored to obtain a polymeric material with an exciting macromolecular architecture.

Different coordination modes of trans-2-{[(2-methoxyphenyl)imino]methyl}phenoxide in rare-earth complexes: influence of the metal cation radius and the number of ligands on steric congestion and ligand coordination modes.

A simple and effective synthetic route to homo- and heteroleptic rare-earth (Ln= Y, La and Nd) complexes with a tridentate Schiff base anion has been demonstrated using exchange reactions of rare-earth chlorides with in-situ-generated sodium (E)-2-{[(2-methoxyphenyl)imino]methyl}phenoxide in different molar ratios in absolute methanol. Five crystal structures have been determined and studied, namely tris(2-{[(2-methoxyphenyl)imino]methyl}phenolato-κ3O1,N,O2)lanthanum, [La(C14H12NO2)3], (1), tris(2-{[(2-methoxyphenyl)imino]methyl}phenolato-κ3O1,N,O2)neodymium tetrahydrofuran disolvate, [La(C14H12NO2)3]·2C4H8O, (2)·2THF, tris(2-{[(2-methoxyphenyl)imino]methyl}phenolato)-κ3O1,N,O2;κ3O1,N,O2;κ2N,O1-yttrium, [Y(C14H12NO2)3], (3), dichlorido-1κCl,2κCl-μ-methanolato-1:2κ2O:O-methanol-2κO-(μ-2-{[(2-methoxyphenyl)imino]methyl}phenolato-1κ3O1,N,O2:2κO1)bis(2-{[(2-methoxyphenyl)imino]methyl}phenolato)-1κ3O1,N,O2;2κ3O1,N,O2-diyttrium-tetrahydrofuran-methanol (1/1/1), [Y2(C14H12NO2)3(CH3O)Cl2(CH4O)]·CH4O·C4H8O, (4)·MeOH·THF, and bis(μ-2-{[(2-methoxyphenyl)imino]methyl}phenolato-1κ3O1,N,O2:2κO1)bis(2-{[(2-methoxyphenyl)imino]methyl}phenolato-2κ3O1,N,O2)sodiumyttrium chloroform disolvate, [NaY(C14H12NO2)4]·2CHCl3, (5)·2CHCl3. Structural peculiarities of homoleptic tris(iminophenoxide)s (1)-(3), binuclear tris(iminophenoxide) (4) and homoleptic ate tetrakis(iminophenoxide) (5) are discussed. The nonflat Schiff base ligand displays μ2-κ3O1,N,O2:κO1 bridging, and κ3O1,N,O2 and κ2N,O1 terminal coordination modes, depending on steric congestion, which in turn depends on the ionic radii of the rare-earth metals and the number of coordinated ligands. It has been demonstrated that interligand dihedral angles of the phenoxide ligand are convenient for comparing steric hindrance in complexes. (4)·MeOH has a flat Y2O2 rhomboid core and exhibits both inter- and intramolecular MeO-H...Cl hydrogen bonding. Catalytic systems based on complexes (1)-(3) and (5) have demonstrated medium catalytic performance in acrylonitrile polymerization, providing polyacrylonitrile samples with narrow polydispersity.