Dinuclear neodymium and lanthanum bis(2,6-diisopropylphenyl) phosphate complexes bearing a hydroxide ligand: catalytic activity of the Nd complex in 1,3-diene polymerization

Chromium complexes bearing disubstituted organophosphate ligands and their use in ethylene polymerization

The crystal structures of three unusual chromium organophosphate complexes have been determined, namely, bis(μ-butyl 2,6-di-tert-butyl-4-methylphenyl hydrogen phosphato-κO:κO′)di-μ-hydroxido-bis[(butyl 2,6-di-tert-butyl-4-methylphenyl hydrogen phosphato-κO)(butyl 2,6-di-tert-butyl-4-methylphenyl phosphato-κO)chromium](Cr—Cr) heptane disolvate or {Cr2(μ2-OH)2[μ2-PO2(OBu)(O-2,6- t Bu2-4-MeC6H2)-κO:κO′]2[PO2(OBu)(O-2,6- t Bu2-4-MeC6H2)-κO]2[HOPO(OBu)(O-2,6- t Bu2-4-MeC6H2)-κO]2}·2C7H16, [Cr2(C19H32O4P)4(C19H33O4P)2(OH)2]·2C7H16, denoted (1)·2(heptane), [μ-bis(2,6-diisopropylphenyl) phosphato-1κO:2κO′]bis[bis(2,6-diisopropylphenyl) phosphato]-1κO,2κO-chlorido-2κCl-triethanol-1κ2 O,2κO-di-μ-ethanolato-1κ2 O:2κ2 O-dichromium(Cr—Cr) ethanol monosolvate or {Cr2(μ2-OEt)2[μ2-PO2(O-2,6-iPr2-C6H3)2-κO:κO′][PO2(O-2,6-iPr2-C6H3)2-κO]2Cl(EtOH)3}·EtOH, [Cr2(C2H5O)2(C24H34O4P)3Cl(C2H6O)3]·C2H6O, denoted (2)·EtOH, and di-μ-ethanolato-1κ2 O:2κ2 O-bis{[bis(2,6-diisopropylphenyl) hydrogen phosphato-κO][bis(2,6-diisopropylphenyl) phosphato-κO]chlorido(ethanol-κO)chromium}(Cr—Cr) benzene disolvate or {Cr2(μ2-OEt)2[PO2(O-2,6-iPr2-C6H3)2-κO]2[HOPO(O-2,6-iPr2-C6H3)2-κO]2Cl2(EtOH)2}·2C6H6, [Cr2(C2H5O)2(C24H34O4P)2(C24H35O4P)2Cl2(C2H6O)2]·2C6H6, denoted (3)·2C6H6. Complexes (1)–(3) have been synthesized by an exchange reaction between the in-situ-generated corresponding lithium or potassium disubstituted phosphates with CrCl3(H2O)6 in ethanol. The subsequent crystallization of (1) from heptane, (2) from ethanol and (3) from an ethanol/benzene mixture allowed us to obtain crystals of (1)·2(heptane), (2)·EtOH and (3)·2C6H6, whose structures have the monoclinic P21, orthorhombic P212121 and triclinic P\overline 1 space groups, respectively. All three complexes have binuclear cores with a single Cr—Cr bond, i.e. Cr2O6P2 in (1), Cr2PO4 in (2) and Cr2O2 in (3), where the Cr atoms are in distorted octahedral environments, formally having 16 ē per Cr atom. The complexes have bridging ligands μ2-OH in (1) or μ2-OEt in (2) and (3). The organophosphate ligands demonstrate terminal κO coordination modes in (1)–(3) and bridging μ2-κO:κO′ coordination modes in (1) and (2). All the complexes exhibit hydrogen bonding: two intramolecular Ophos...H—Ophos interactions in (1) and (3) form two {H[PO2(OR)2]2} associates; two intramolecular Cl...H—OEt hydrogen bonds additionally stabilize the Cr2O2 core in (3); two intramolecular Ophos...H—OEt interactions and two O...H—O intermolecular hydrogen bonds with a noncoordinating ethanol molecule are observed in (2)·EtOH. The presence of both basic ligands (OH− or OEt−) and acidic [H(phosphate)2]− associates at the same metal centres in (1) and (3) is rather unusual. Complexes may serve as precatalysts for ethylene polymerization under mild conditions, providing polyethylene with a small amount of short-chain branching. The formation of a small amount of α-olefins has been detected in this reaction.

Crystal structure of tris-[bis-(2,6-diiso-propyl-phen-yl) phosphato-κO]penta-kis-(methanol-κO)europium methanol monosolvate

The mononuclear title complex, [Eu(C24H34O4P)3(CH4O)5]·CH4O, (1), has been obtained as a minor product in the reaction between EuCl3(H2O)6 and lithium bis-(2,6-diiso-propyl-phen-yl) phosphate in a 1:3 molar ratio in a methanol medium. Its structure exhibits monoclinic (P21/c) symmetry at 120 K and is isostructural with the La, Ce and Nd analogs reported previously [Minyaev et al. (2018a ▸). Acta Cryst. C74, 590-598]. In (1), all three bis-(2,6-diiso-propyl-phen-yl) phosphate ligands display the terminal κ1 O-coordination mode. All of the hy-droxy H atoms are involved in O-H⋯O hydrogen bonding, exhibiting four intra-molecular and two inter-molecular hydrogen bonds. Photophysical studies have demonstrated luminescence of (1) with a low quantum yield.

Bis[μ-bis-(2,6-diiso-propyl-phen-yl) phosphato-κ2 O:O']bis-[(2,2'-bi-pyridine-κ2 N,N')lithium] toluene disolvate and its catalytic activity in ring-opening polymerization of ∊-caprolactone and l-dilactide

The solvated centrosymmmtric title compound, [Li2(C24H34O4P)2(C10H8N2)2]·2C7H8, was formed in the reaction between {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) and 2,2'-bi-pyridine (bipy) in toluene. The structure has monoclinic (P21/n) symmetry at 120 K and the asymmetric unit consists of half a complex mol-ecule and one mol-ecule of toluene solvent. The diaryl phosphate ligand demonstrates a μ-κO:κO'-bridging coordination mode and the 2,2'-bi-pyridine ligand is chelating to the Li+ cation, generating a distorted tetra-hedral LiN2O2 coordination polyhedron. The complex exhibits a unique dimeric Li2O4P2 core. One isopropyl group is disordered over two orientations in a 0.621 (4):0.379 (4) ratio. In the crystal, weak C-H⋯O and C-H⋯π inter-actions help to consolidate the packing. Catalytic systems based on the title complex and on the closely related complex {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) display activity in the ring-opening polymerization of ∊-caprolactone and l-dilactide.

Crystal structure of bis(μ2-tri-phenyl-acetato-κO:κO')bis(diisobutylaluminium)

Single crystals of the title compound, [Al(iBu)2(O2CCPh3)]2 or [Al2(C4H9)4(C20H15O2)2], have been formed in the reaction between tris-(tetra-hydro-furan)-tris-(tri-phenyl-acetato)-neodymium, [Nd(Ph3CCOO)3(THF)3], and triiso-butyl-aluminium, Al(iBu)3, in hexane followed by low-temperature crystallization (243 K) from the reaction mixture. The structure has triclinic (P ) symmetry at 120 K. The dimeric complex [Al(iBu)2(O2CCPh3-μ-κO:κO')]2 is located about an inversion centre. The tri-phenyl-acetate ligand displays a μ-κO:κO'-bridging coordination mode, leading to the formation of an octa-gonal Al2O4C2 core. The complex displays HPh⋯CPh inter-molecular inter-actions.

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.

[Bis(2,6-diiso-propyl-phen-yl) phosphato-κO]pentakis-(methanol-κO)manganese bis-(2,6-diiso-propyl-phen-yl) phosphate methanol tris-olvate

The title compound, [Mn(C24H34O4P)(CH3OH)5](C24H34O4P)·3CH3OH, was formed in the reaction between a hydrate of a manganese(II) salt [either Mn(NO3)2(H2O)6 or MnCl2(H2O)4] with a methanol solvate of lithium bis-(2,6-diiso-propyl-phen-yl) phosphate, {Li[OOP(O-2,6- i Pr2C6H3)2]·(CH4O)3}·CH4O, in methanol. The structure has monoclinic (Cc) symmetry at 150 K. The complex consists of an [Mn{OOP(O-2,6- i Pr2C6H3)2}(CH3OH)5]+ cation, an [OOP(O-2,6- i Pr2C6H3)2]- anion and three non-coordinating methanol mol-ecules. The anion demonstrates disorder of an isopropyl group [occupancy ratio is 0.57 (4):0.43 (4)]. The di-aryl-phosphate ligand in the cation exhibits a κ1 O terminal coordination mode. The Mn atom is in a nearly unperturbed octa-hedral environment. The [Mn{OOP(O-2,6- i Pr2C6H3)2}(CH3OH)5]+ cation exhibits one intra-molecular O-H⋯O bond, and is coordinated via two inter-molecular O-H⋯O hydrogen bonds to the [OOP(O-2,6- i Pr2C6H3)2]- anion. The cations, anions and non-coordinating methanol mol-ecules are linked into infinite chains along the c-axis direction via 0-H⋯O hydrogen bonding. The complex is of inter-est as a possible inhibitor for the thermal decomposition of polydi-methyl-siloxane. The crystal studied was refined as an inversion twin with a domain ratio of 0.47 (3):0.53 (3).