Isomorphous rare‐earth tris[bis(2,6‐diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3‐diene polymerization and in the inhibited oxidation of polydimethylsiloxane

Crystals of mononuclear tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]pentakis(methanol‐κO)lanthanide methanol monosolvates of lanthanum, [La(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 1 ), cerium, [Ce(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 2 ), and neodymium, [Nd(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 3 ), have been obtained by reactions between LnCl₃(H₂O)_n (n = 6 or 7) and lithium bis(2,6‐diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds ( 1 )–( 3 ) crystallize in the monoclinic P2₁/c space group and have isomorphous crystal structures. All three bis(2,6‐diisopropylphenyl) phosphate ligands display a κO‐monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅] molecular unit exhibits four intramolecular O—H…O hydrogen bonds, forming six‐membered rings. The unit forms two intermolecular O—H…O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅]·CH₃OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen‐bond network. Complexes ( 1 )–( 3 ) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound ( 2 ) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]neodymium, ( 3′ ), which was obtained as a dry powder of ( 3 ) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.     

Isomorphous rare‐earth bis[bis(2,6‐diisopropylphenyl)phosphate] complexes and their self‐assembly into two‐dimensional frameworks by intramolecular hydrogen bonds

The crystal structures of rare‐earth diaryl‐ or dialkylphosphate derivatives are poorly explored. Crystals of bis[bis(2,6‐diisopropylphenyl)phosphato‐κO ]chloridotetrakis(methanol‐κO )neodymium methanol disolvate, [Nd(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (1), and of the lutetium, [Lu(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (2), and yttrium, [Y(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (3), analogues have been obtained by reactions between lithium bis(2,6‐diisopropylphenyl)phosphate and LnCl₃(H₂O)₆ (in a 2:1 ratio) in methanol. Compounds (1)–(3) crystallize in the C 2/c space group. Their crystal structures are isomorphous. The molecule possesses C ₂ symmetry with a twofold crystallographic axis passing through the Ln and Cl atoms. The bis(2,6‐diisopropylphenyl)phosphate ligands all display a κ¹O‐monodentate coordination mode. The coordination polyhedron for the metal atom [coordination number (CN) = 7] is a distorted pentagonal bipyramid. Each [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₂Cl(CH₃OH)₄] molecular unit exhibits two intramolecular O—H…O hydrogen bonds, forming six‐membered rings, and two intramolecular O—H…Cl interactions, forming four‐membered rings. Intermolecular O—H…O hydrogen bonds connect each unit via four noncoordinating methanol molecules with four other units, forming a two‐dimensional hydrogen‐bond network. Crystals of bis[bis(2,6‐diisopropylphenyl)phosphato‐κO ]tetrakis(methanol‐κO )(nitrato‐κ²O ,O ′)neodymium methanol disolvate, [Nd(C₂₄H₃₄O₄P)(NO₃)(CH₄O)₄]·2CH₃OH, (4), have been obtained in an analogous manner from NdCl₃(H₂O)₆. Compound (4) also crystalizes in the C 2/c space group. Its crystal structure is similar to those of (1)–(3). The κ²O ,O ′‐bidentate nitrate anion is disordered over a twofold axis, being located nearly on it. Half of the molecule is crystallographically unique (CN_Nd = 8). Unlike (1)–(3), complex (4) exhibits disorder of all three methanol molecules, one isopropyl group of the phosphate ligand and the NO₃⁻ ligand. The structure of (4) displays intra‐ and intermolecular O—H…O hydrogen bonds similar to those in (1)–(3). Compounds (1)–(4) represent the first reported mononuclear bis[bis(diaryl/dialkyl)phosphate] rare‐earth complexes.     

Encapsulation of Triphenylene Derivatives in the Hexanuclear Arene Ruthenium Metallo‐Prismatic Cage [Ru6(p‐PriC6H4Me)6(tpt)2(dhbq)3]6+ (tpt = 2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine,dhbq = 2,5‐dihydroxy‐1,4‐benzoquinonato)

A large cationic triangular metallo‐prism, [Ru₆(p‐PrⁱC₆H₄Me)₆(tpt)₂(dhbq)₃]⁶⁺ ( 1 )⁶⁺, incorporating p‐cymene ruthenium building blocks, bridged by 2,5‐dihydroxy‐1,4‐benzoquinonato (dhbq) ligands, and connected by two 2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine (tpt) subunits, allows the permanent encapsulation of the triphenylene derivatives hexahydroxytriphenylene, C₁₈H₆(OH)₆ and hexamethoxytriphenylene, C₁₈H₆(OMe)₆. These two cationic carceplex systems [C₁₈H₆(OH)₆⊂ 1 ]⁶⁺ and [C₁₈H₆(OMe)₆⊂ 1 ]⁶⁺ have been isolated as their triflate salts. The molecular structure of these systems has been established by one‐dimensional ¹H ROESY NMR experiments as well as by the single‐crystal structure analysis of [C₁₈H₆(OMe)₆⊂ 1 ][O₃SCF₃]₆.     

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‐^tBu₂‐4‐MeC₆H₂)‐κO:κO′]₂[PO₂(OBu)(O‐2,6‐^tBu₂‐4‐MeC₆H₂)‐κO]₂[HOPO(OBu)(O‐2,6‐^tBu₂‐4‐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‐1κ²O,2κO‐di‐μ‐ethanolato‐1κ²O:2κ²O‐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‐1κ²O:2κ²O‐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 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 O_phos…H—O_phos interactions in ( 1 ) and ( 3 ) form two {H[PO₂(OR)₂]₂} associates; two intramolecular Cl…H—O_Et hydrogen bonds additionally stabilize the Cr₂O₂ core in ( 3 ); two intramolecular O_phos…H—O_Et 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.     

Bis[μ3‐1,8‐bis(triisopropylsilylamido)naphthalene]bis(tetrahydrofuran)di‐μ3‐oxido‐dimanganese(III)disodium

The solid‐state structure of the title compound, [Na₂Mn₂(C₃₂H₅₆N₂OSi₂)₂O₂] or [1,8‐C₁₀H₆(NSiⁱPr₃)₂Mn(μ₃‐O)Na(THF)]₂, which lies across a crystallographic twofold axis, exhibits a central [Mn₂O₂Na₂]⁴⁺ core, with two oxide groups, each triply bridging between the two Mn^III ions and an Na⁺ ion. Additional coordination is provided to each Mn^III centre by a 1,8‐C₁₀H₆(NSiⁱPr₃)₂ [1,8‐bis(triisopropylsilylamido)naphthalene] ligand and to the Na⁺ centres by a tetrahydrofuran molecule. The presence of an additional Na...H—C agostic interaction potentially contributes to the distortion around the bridging oxide group.     

Synthesis,Interionic Structure,and Reactivity toward CO and p‐Methylstyrene of Palladacyclic Compounds Bearing α‐Diimine Ligands

Palladacyclic compounds [Pd(C₆H₄(C₆H₅C?O)C?N? R)(N? N)] [X] (R = Et, ⁱPr, 2,6‐ⁱPr₂C₆H₃; N? N = bpy = 2,2′‐bipyridine, or 1,4‐(o,o′‐dialkylaryl)‐1,4‐diazabuta‐1,3‐dienes; [X]^? = [BF₄]^? or [PF₆]^?) were synthesized from the dimers [{Pd(C₆H₄(C₆H₅C?O)C?N? R)(μ‐Cl)}₂] and N? N ligands. Their interionic structure in CD₂Cl₂ was determined by means of ¹⁹F,¹H‐HOESY experiments and compared with that in the solid state derived from X‐ray single‐crystal studies. [Pd(C₆H₄(C₆H₅C?O)C?N? R)(N? N)] [X] complexes were found to copolymerize CO and p‐methylstyrene affording syndiotactic or isotactic copolymers when bpy or 1,4‐(o,o′‐dimethylaryl)‐1,4‐diazabuta‐1,3‐dienes were used, respectively. The reactions with CO and p‐methylstyrene of the bpy derivatives were investigated. Two intermediates derived from a single and a double insertion of CO into the Pd? C bonds were isolated and completely characterized in solution.     

Efficient ethylene/norbornene copolymerization by half‐titanocenes containing imidazolin‐2‐iminato ligands and MAO catalyst systems

Ethylene copolymerizations with norbornene (NBE) using half‐titanocenes containing imidazolin‐2‐iminato ligands, Cp′TiCl₂[1,3‐R₂(CHN)₂C?N] [Cp′ = Cp ( 1 ), ^tBuC₅H₄ ( 2 ); R = ^tBu ( a ), 2,6‐ⁱPr₂C₆H₃ ( b )], have been explored in the presence of methylaluminoxane (MAO) cocatalyst. Complex 1a exhibited remarkable catalytic activity with better NBE incorporation, affording high‐molecular‐weight copolymers with uniform molecular weight distributions, whereas the tert‐BuC₅H₄ analog ( 2a ) showed low activity, and the resultant polymer prepared by the Cp‐2,6‐diisopropylphenyl analog ( 1b ) possessed broad molecular weight distribution. The microstructure analysis of the poly(ethylene‐co‐NBE)s prepared by 1a suggests the formation of random copolymers including two and three NBE repeating units. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2575–2580     

Bis(β‐diketiminato) lanthanide amides: synthesis,structure and catalysis for the polymerization of l‐lactide and ε‐caprolactone

Treatment of the chlorides (L^2,6‐iPr2_Ph)₂LnCl (L^2,6‐iPr2_Ph = [(2,6‐ⁱPr₂C₆H₃)NC(Me)CHC(Me)N(C₆H₅)]^?) with 1 equiv. of NaNH(2,6‐ⁱPr₂C₆H₃) afforded the monoamides (L^2,6‐iPr2_Ph)₂LnNH(2,6‐ⁱPr₂C₆H₃) (Ln = Y ( 1 ), Yb ( 2 )) in good yields. Anhydrous LnCl₃ reacted with 2 equiv. of NaL^2,6‐iPr2_Ph in THF, followed by treatment with 1 equiv. of NaNH(2,6‐ⁱPr₂C₆H₃), giving the analogues (L^2,6‐iPr2_Ph)₂LnNH(2,6‐ⁱPr₂C₆H₃) (Ln = Sm ( 3 ), Nd ( 4 )). Two monoamido complexes stabilized by two L^2‐Me ligands, (L^2‐Me)₂LnNH(2,6‐ⁱPr₂C₆H₃) (L^2‐Me = [N(2‐MeC₆H₄)C(Me)]₂CH)^?; Ln = Y ( 5 ), Yb ( 6 )), were also synthesized by the latter route. Complexes 1 , 2 , 3 , 4 , 5 , 6 were fully characterized, including X‐ray crystal structure analyses. Complexes 1 , 2 , 3 , 4 , 5 , 6 are isostructural. The central metal in each complex is ligated by two β‐diketiminato ligands and one amido group in a distorted trigonal bipyramid. All the complexes were found to be highly active in the ring‐opening polymerization of L‐lactide (L‐LA) and ε‐caprolactone (ε‐CL) to give polymers with relatively narrow molar mass distributions. The activity depends on both the central metal and the ligand (Yb < Y < Sm ≈ Nd and L^2‐Me < L^2,6‐iPr2_Ph). Remarkably, the binary 3/benzyl alcohol (BnOH) system exhibited a striking ‘immortal’ nature and proved able to quantitatively convert 5000 equiv. of L‐LA with up to 100 equiv. of BnOH per metal initiator. All the resulting PLAs showed monomodal, narrow distributions (M_w/M_n = 1.06 ? 1.08), with molar mass (M_n) decreasing proportionally with an increasing amount of BnOH. The binary 4/BnOH system also exhibited an ‘immortal’ nature in the polymerization of ε‐CL in toluene. Copyright © 2014 John Wiley & Sons, Ltd.     

Vinyl polymerization of norbornene by mono‐ and trinuclear nickel complexes with indanimine ligands

A series of new indanimine ligands [ArN?CC₂H₃(CH₃)C₆H₂(R)OH] (Ar = Ph, R = Me ( 1 ), R = H ( 2 ), and R = Cl ( 3 ); Ar = 2,6‐i‐Pr₂C₆H₃, R = Me ( 4 ), R = H ( 5 ), and R = Cl ( 6 )) were synthesized and characterized. Reaction of indanimines with Ni(OAc)₂·4H₂O results in the formation of the trinuclear hexa(indaniminato)tri (nickel(II)) complexes Ni₃[ArN = CC₂H₃(CH₃)C₆H₂(R)O]₆ (Ar = Ph, R = Me ( 7 ), R = H ( 8 ), and R = Cl ( 9 )) and the mononuclear bis(indaniminato)nickel (II) complexes Ni[ArN?CC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6‐i‐Pr₂C₆H₃, R = Me ( 10 ), R = H ( 11 ), and R = Cl ( 12 )). All nickel complexes were characterized by their IR, NMR spectra, and elemental analyses. In addition, X‐ray structure analyses were performed for complexes 7 , 10 , 11 , and 12 . After being activated with methylaluminoxane (MAO), these nickel(II) complexes can polymerize norbornene to produce addition‐type polynorbornene (PNB) with high molecular weight M_v (10⁶ g mol^?1), highly catalytic activities up to 2.18 × 10⁷ gPNB mol^?1 Ni h^?1. Catalytic activities and the molecular weight of PNB have been investigated for various reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 489–500, 2008     

Cationic,neutral and anionic metal(II) complexes derived from 4‐oxo‐4H‐pyran‐2,6‐dicarboxylic acid (chelidonic acid)

The structures of five metal complexes containing the 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate dianion illustrate the remarkable coordinating versatility of this ligand and the great structural diversity of its complexes. In tetraaquaberyllium 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate, [Be(H₂O)₄](C₇H₂O₆), (I), the ions are linked by eight independent O—H...O hydrogen bonds to form a three‐dimensional hydrogen‐bonded framework structure. Each of the ions in hydrazinium(2+) diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)calcate, (N₂H₆)[Ca(C₇H₂O₆)₂(H₂O)₂], (II), lies on a twofold rotation axis in the space group P2/c; the anions form hydrogen‐bonded sheets which are linked into a three‐dimensional framework by the cations. In bis(μ‐4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)bis[tetraaquamanganese(II)] tetrahydrate, [Mn₂(C₇H₂O₆)₂(H₂O)₈]·4H₂O, (III), the metal ions and the organic ligands form a cyclic centrosymmetric Mn₂(C₇H₂O₆)₂ unit, and these units are linked into a complex three‐dimensional framework structure containing 12 independent O—H...O hydrogen bonds. There are two independent Cu^II ions in tetraaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)copper(II), [Cu(C₇H₂O₆)(H₂O)₄], (IV), and both lie on centres of inversion in the space group P; the metal ions and the organic ligands form a one‐dimensional coordination polymer, and the polymer chains are linked into a three‐dimensional framework containing eight independent O—H...O hydrogen bonds. Diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)cadmium monohydrate, [Cd(C₇H₂O₆)(H₂O)₂]·H₂O, (V), forms a three‐dimensional coordination polymer in which the organic ligand is coordinated to four different Cd sites, and this polymer is interwoven with a complex three‐dimensional framework built from O—H...O hydrogen bonds.     

Construction of (3,8)‐connected three‐dimensional cobalt(II) and copper(II) coordination polymers with 1,3‐bis[(1,2,4‐triazol‐4‐yl)methyl]benzene and benzene‐1,3,5‐tricarboxylate ligands

Coordination polymers (CPs) have been widely studied because of their diverse and adjustable topologies and wide‐ranging applications in luminescence, chemical sensors, magnetism, photocatalysis, gas adsorption and separation. In the present work, two coordination polymers, namely poly[(μ₅‐benzene‐1,3,5‐tricarboxylato‐κ⁶O¹:O^1′:O³:O³:O⁵,O^5′){μ₃‐1,3‐bis[(1,2,4‐triazol‐4‐yl)methyl]benzene‐κ³N:N′:N′′}di‐μ₃‐hydroxido‐dicobalt(II)], [Co₂(C₉H₃O₆)(OH)(C₁₂H₁₂N₆)]_n or [Co₂(btc)(OH)(mtrb)]_n, (1), and poly[[diaquabis(μ₃‐benzene‐1,3,5‐tricarboxylato‐κ³O¹:O³:O⁵)bis{μ₃‐1,3‐bis[(1,2,4‐triazol‐4‐yl)methyl]benzene‐κ³N:N′:N′′}tetra‐μ₃‐hydroxido‐tetracopper(II)] monohydrate], {[Cu₄(C₉H₃O₆)₂(OH)₂(C₁₂H₁₂N₆)₂(H₂O)₂]·H₂O}_n or {[Cu₄(btc)₂(OH)₂(mtrb)₂(H₂O)₂]·H₂O}_n, (2), were synthesized by the hydrothermal method using 1,3‐bis[(1,2,4‐triazol‐4‐yl)methyl]benzene (mtrb) and benzene‐1,3,5‐tricarboxylate (btc^3?). CP (1) exhibits a (3,8)‐coordinated three‐dimensional (3D) network of the 3,8T38 topological type, with a point symbol of {4,5,6}₂{4²·5⁶·6¹⁶·7²·8²}, based on the tetranuclear hydroxide cobalt(II) cluster [Co₄(μ₃‐OH)₂]. CP (2) shows a (3,8)‐coordinated tfz‐d topology, with a point symbol of {4₃}₂{4⁶·6¹⁸·8⁴}, based on the tetranuclear hydroxide copper(II) cluster [Cu₄(μ₃‐OH)₂]. The different (3,8)‐coordinated 3D networks based on tetranuclear hydroxide–metal clusters of (1) and (2) are controlled by the different central metal ions [Co^II for (1) and Cu^II for (2)]. The thermal stabilities and solid‐state optical diffuse‐reflection spectra were measured. The energy band gaps (E_g) obtained for (1) and (2) were 2.72 and 2.29 eV, respectively. CPs (1) and (2) exhibit good photocatalytic degradation of the organic dyes methylene blue (MB) and rhodamine B (RhB) under visible‐light irradiation.     

The Ruthenostannylene Complex [Cp*(IXy)H2Ru‐Sn‐Trip]: Providing Access to Unusual Ru‐Sn Bonded Stanna‐imine,Stannene, and Ketenylstannyl Complexes

Reactivity studies of the thermally stable ruthenostannylene complex [Cp*(IXy)(H)₂Ru? Sn? Trip] ( 1 ; IXy=1,3‐bis(2,6‐dimethylphenyl)imidazol‐2‐ylidene; Cp*=η⁵‐C₅Me₅; Trip=2,4,6‐iPr₃C₆H₂) with a variety of organic substrates are described. Complex 1 reacts with benzoin and an α,β‐unsaturated ketone to undergo [1+4] cycloaddition reactions and afford [Cp*(IXy)(H)₂RuSn(κ²‐O,O‐OCPhCPhO)Trip] ( 2 ) and [Cp*(IXy)(H)₂RuSn(κ²‐O,C‐OCPhCHCHPh)Trip] ( 3 ), respectively. The reaction of 1 with ethyl diazoacetate resulted in a tin‐substituted ketene complex [Cp*(IXy)(H)₂RuSn(OC₂H₅)(CHCO)Trip] ( 4 ), which is most likely a decomposition product from the putative ruthenium‐substituted stannene complex. The isolation of a ruthenium‐substituted stannene [Cp*(IXy)(H)₂RuSn(?Flu)Trip] ( 5 ) and stanna‐imine [Cp*(IXy)(H)₂RuSn(κ²‐N,O‐NSO₂C₆H₄Me)Trip] ( 6 ) complexes was achieved by treatment of 1 with 9‐diazofluorene and tosyl azide, respectively.     

The Ruthenostannylene Complex [Cp*(IXy)H2Ru‐Sn‐Trip]: Providing Access to Unusual Ru‐Sn Bonded Stanna‐imine,Stannene, and Ketenylstannyl Complexes

Reactivity studies of the thermally stable ruthenostannylene complex [Cp*(IXy)(H)₂Ru Sn Trip] ( 1 ; IXy=1,3‐bis(2,6‐dimethylphenyl)imidazol‐2‐ylidene; Cp*=η⁵‐C₅Me₅; Trip=2,4,6‐iPr₃C₆H₂) with a variety of organic substrates are described. Complex 1 reacts with benzoin and an α,β‐unsaturated ketone to undergo [1+4] cycloaddition reactions and afford [Cp*(IXy)(H)₂RuSn(κ²‐O,O‐OCPhCPhO)Trip] ( 2 ) and [Cp*(IXy)(H)₂RuSn(κ²‐O,C‐OCPhCHCHPh)Trip] ( 3 ), respectively. The reaction of 1 with ethyl diazoacetate resulted in a tin‐substituted ketene complex [Cp*(IXy)(H)₂RuSn(OC₂H₅)(CHCO)Trip] ( 4 ), which is most likely a decomposition product from the putative ruthenium‐substituted stannene complex. The isolation of a ruthenium‐substituted stannene [Cp*(IXy)(H)₂RuSn(Flu)Trip] ( 5 ) and stanna‐imine [Cp*(IXy)(H)₂RuSn(κ²‐N,O‐NSO₂C₆H₄Me)Trip] ( 6 ) complexes was achieved by treatment of 1 with 9‐diazofluorene and tosyl azide, respectively.     

From a Phosphaketenyl‐Functionalized Germylene to 1,3‐Digerma‐2,4‐diphosphacyclobutadiene

The first 4π‐electron resonance‐stabilized 1,3‐digerma‐2,4‐diphosphacyclobutadiene [L^H₂Ge₂P₂] 4 (L^H=CH[CHNDipp]₂ Dipp=2,6‐ⁱPr₂C₆H₃) with four‐coordinate germanium supported by a β‐diketiminate ligand and two‐coordinate phosphorus atoms has been synthesized from the unprecedented phosphaketenyl‐functionalized N‐heterocyclic germylene [L^HGe‐P=C=O] 2 a prepared by salt‐metathesis reaction of sodium phosphaethynolate (P≡C?ONa) with the corresponding chlorogermylene [L^HGeCl] 1 a . Under UV/Vis light irradiation at ambient temperature, release of CO from the P=C=O group of 2 a leads to the elusive germanium–phosphorus triply bonded species [L^HGe≡P] 3 a , which dimerizes spontaneously to yield black crystals of 4 as isolable product in 67 % yield. Notably, release of CO from the bulkier substituted [L^tBuGe‐P=C=O] 2 b (L^tBu=CH[C(^tBu)N‐Dipp]₂) furnishes, under concomitant extrusion of the diimine [Dipp‐NC(^tBu)]₂, the bis‐N,P‐heterocyclic germylene [DippNC(^tBu)C(H)PGe]₂ 5 .     

Two isomorphous crotonatolanthanide complexes: tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)Ln]–2,6‐diaminopurine (1/2) (Ln = Dy and Ho)

The title isomorphous compounds, tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)dysprosium(III)]–2,6‐diaminopurine (1/2), [Dy₂(C₄H₅O₂)₆(H₂O)₄]·2C₅H₆N₆, and tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)holmium(III)]–2,6‐diaminopurine (1/2), [Ho₂(C₄H₅O₂)₆(H₂O)₄]·2C₅H₆N₆, consist of [Ln(crot)₃(H₂O)₂]₂ dimers (crot is crotonate or but‐2‐enoate; Ln is the lanthanide cation), built up around inversion centres and completed by 2,6‐diaminopurine molecules. The lanthanide cation is coordinated by three chelating crotonate units and two water molecules. One of the chelating carboxylate groups acts also in a bridging mode sharing one O atom with both cations and the final result is a pair of DyO₉ tricapped prismatic polyhedra linked to each other through a central (Dy—O)₂ loop. A feature of the structures is the existence of a complex intermolecular interaction scheme involving two sets of tightly interlinked non‐intersecting one‐dimensional structures, one of them formed by the [Dy(crot)₃(H₂O)₂]₂ dimers (running along [100] and linked by O—H...O hydrogen bonds) and the second formed by 2,6‐diaminopurine molecules (evolving along [010] linked by N—H...N hydrogen bonds).     

A three‐dimensional coordination polymer based on the Zn4(μ3‐OH)2 unit: poly[[(μ4‐benzene‐1,4‐dicarboxylato)bis(μ3‐benzene‐1,4‐dicarboxylato)bis(μ3‐hydroxido)bis(1,10‐phenanthroline‐5,6‐dione)tetrazinc] dihydrate]

The title compound, {[Zn₄(C₈H₄O₄)₃(OH)₂(C₁₂H₆N₂O₂)₂]·2H₂O}_n, has been prepared hydrothermally by the reaction of Zn(NO₃)₂·6H₂O with benzene‐1,4‐dicarboxylic acid (H₂bdc) and 1,10‐phenanthroline‐5,6‐dione (pdon) in H₂O. In the crystal structure, a tetranuclear Zn₄(OH)₂ fragment is located on a crystallographic inversion centre which relates two subunits, each containing a [ZnN₂O₄] octahedron and a [ZnO₄] tetrahedron bridged by a μ₃‐OH group. The pdon ligand chelates to zinc through its two N atoms to form part of the [ZnN₂O₄] octahedron. The two crystallographically independent bdc²⁻ ligands are fully deprotonated and adopt μ₃‐κO:κO′:κO′′ and μ₄‐κO:κO′:κO′′:κO′′′ coordination modes, bridging three or four Zn^II cations, respectively, from two Zn₄(OH)₂ units. The Zn₄(OH)₂ fragment connects six neighbouring tetranuclear units through four μ₃‐bdc²⁻ and two μ₄‐bdc²⁻ ligands, forming a three‐dimensional framework with uninodal 6‐connected α‐Po topology, in which the tetranuclear Zn₄(OH)₂ units are considered as 6‐connected nodes and the bdc²⁻ ligands act as linkers. The uncoordinated water molecules are located on opposite sides of the Zn₄(OH)₂ unit and are connected to it through hydrogen‐bonding interactions involving hydroxide and carboxylate groups. The structure is further stabilized by extensive π–π interactions between the pdon and μ₄‐bdc²⁻ ligands.     

Solvent dependence of the solid‐state structures of salicylaldiminate magnesium amide complexes

There are challenges in using magnesium coordination complexes as reagents owing to their tendency to adopt varying aggregation states in solution and thus impacting the reactivity of the complexes. Many magnesium complexes are prone to ligand redistribution via Schlenk equilibrium due to the ionic character within the metal–ligand interactions. The role of the supporting ligand is often crucial for providing stability to the heteroleptic complex. Strategies to minimize ligand redistribution in alkaline earth metal complexes could include using a supporting ligand with tunable sterics and electronics to influence the degree of association to the metal atom. Magnesium bis(hexamethyldisilazide) was reacted with salicylaldimines [¹L = N‐(2,6‐diisopropylphenyl)salicylaldimine and ²L = 3,5‐di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)salicylaldimine] in either nondonor (toluene) or donor solvents [tetrahydrofuran (THF) or pyridine]. The structures of the magnesium complexes were studied in the solid state via X‐ray diffraction. In the nondonor solvent, i.e. toluene, the heteroleptic complex bis{μ‐2‐[(2,6‐diisopropylphenyl)iminomethyl]phenolato}‐κ³N,O:O;κ³O:N,O‐bis[(hexamethyldisilazido‐κN)magnesium(II)], [Mg₂(C₁₉H₂₂NO)₂(C₆H₁₈NSi₂)₂] or [¹LMgN(SiMe₃)₂]₂, (1), was favored, while in the donor solvent, i.e. pyridine (pyr), the formation of the homoleptic complex {2,4‐di‐tert‐butyl‐6‐[(2,6‐diisopropylphenyl)iminomethyl]phenolato‐κ²N,O}bis(pyridine‐κN)magnesium(II) toluene monosolvate, [Mg(C₂₇H₃₈NO)₂(C₅H₅N)₂]·C₅H₅N or [{²L₂Mg₂(pyr)₂}·pyr], (2), predominated. Heteroleptic complex (1) was crystallized from toluene, while homoleptic complexes (2) and the previously reported [¹L₂Mg·THF] [Quinque et al. (2011). Eur. J. Inorg. Chem. pp. 3321–3326] were crystallized from pyridine and THF, respectively. These studies support solvent‐dependent ligand redistribution in solution. In‐situ¹H NMR experiments were carried out to further probe the solution behavior of these systems.     

A new one‐dimensional cadmium(II) coordination polymer incorporating 4‐[4‐(1H‐imidazol‐1‐yl)phenyl]pyridine and 5‐hydroxybenzene‐1,3‐dicarboxylate ligands

The design and synthesis of new organic lgands is important to the rapid development of coordination polymers (CPs). However, CPs based on asymmetric ligands are still rare, mainly because such ligands are usually expensive and more difficult to synthesize. The new asymmetric ligand 4‐[4‐(1H‐imidazol‐1‐yl)phenyl]pyridine (IPP) has been used to construct the title one‐dimensional coordination polymer, catena‐poly[[[aqua{4‐[4‐(1H‐imidazol‐1‐yl‐κN³)phenyl]pyridine}cadmium(II)]‐μ‐5‐hydroxybenzene‐1,3‐dicarboxylato‐κ³O¹,O^1′:O³] monohydrate], {[Cd(C₈H₄O₅)(C₁₄H₁₁N₃)₂(H₂O)]·H₂O}_n, under hydrothermal reaction of IPP with Cd^II in the presence of 5‐hydroxyisophthalic acid (5‐OH‐H₂bdc). The Cd^II cation is coordinated by two N atoms from two distinct IPP ligands, three carboxylate O atoms from two different 5‐OH‐bdc²⁻ dianionic ligands and one water O atom in a distorted octahedral geometry. The cationic [Cd(IPP)₂]²⁺ nodes are linked by 5‐OH‐bdc²⁻ ligands to generate a one‐dimensional chain. These chains are extended into a two‐dimensional layer structure via O—H…O and O—H…N hydrogen bonds and π–π interactions.     

Synthesis of 2‐(N‐arylimino)pyrrolide nickel complexes and polymerization of methyl methacrylate

The synthesis, characterization and methyl methacrylate polymerization behaviors of 2‐(N‐arylimino)pyrrolide nickel complexes are described. The nickel complex [NN]₂Ni ( 1 , [NN] = [2‐C(H)NAr‐5‐tBu‐C₄H₂N]^?, Ar = 2,6‐iPr₂C₆H₃) was prepared in good yield by the reaction of [NN]Li with trans‐[Ni(Cl)(Ph)(PPh₃)₂] in THF. Reaction of [NN]Li with NiBr₂(DME) yielded the nickel bromide [NN]Ni(Br)[NNH] ( 2 ). Complexes 1 and 2 were characterized by ¹H NMR and IR spectroscopy and elemental analysis, and by X‐ray single crystal analysis. Both complexes, upon activation with methylaluminoxane, are highly active for the polymerization of methyl methacrylate to give high molecular weight polymethylmethacrylate with narrow molecular distributions. Copyright © 2009 John Wiley & Sons, Ltd.     

Di‐μ‐hydro­xo‐bis­(diiso­propyl­gallium)–1,4,8,11‐tetra­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane (1/1)

The hydro­lysis product [Ga₂(C₃H₇)₄(OH)₂]·C₁₄H₃₂N₄, derived from the tetrakis­(triiso­propyl­gallium)–1,4,8,11‐tetra­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane (1/1) adduct, consists of a centrosymmetric [ⁱPr₂Ga(μ‐OH)]₂ unit hydrogen bonded through the hydroxyl group to a nitro­gen on an adjacent centrosymmetric 1,4,8,11‐tetra­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane molecule, resulting in the generation of a molecular chain through the crystal.