Amidometallate von Seltenerdelementen. Synthese und Kristallstrukturen von [Na(12-Krone-4)2][M{N(SiMe3)2}3(OSiMe3)] (M = Sm,Yb), [Na(THF)3Sm{N(SiMe3)2}3(C≡C–Ph)], [Na(THF)6][Lu2(μ-NH2)(μ-NSiMe3){N(SiMe3)2}4] sowie von [NaN(SiMe3)2(THF)]2. Anwendungen der Seltenerdkomplexe als Polymerisationskatalysatoren

Amido Metalates of Rare Earth Elements. Syntheses and Crystal Structures of [Na(12-crown-4)₂][M{N(SiMe₃)₂}₃(OSiMe₃)] (M = Sm, Yb), [Na(THF)₃Sm{N(SiMe₃)₂}₃(C≡C–Ph)], [Na(THF)₆][Lu₂(μ-NH₂)(μ-NSiMe₃){N(SiMe₃)₂}₄], and of [NaN(SiMe₃)₂(THF)]₂. Applications of Rare Earth Metal Complexes as Polymerization Catalysts The amido silyloxy complexes [Na(12-crown-4)₂][M{N(SiMe₃)₂}₃(OSiMe₃)] with M = Sm ( 1 a ), Eu ( 1 b ), Yb ( 1 c ), and Lu ( 1 d ) were obtained from the trisamides M[N(SiMe₃)₃]₃ and NaOSiMe₃ in n-hexane in the presence of 12-crown-4; they form yellow to orange-red crystals, of which 1 a and 1 c were characterized crystallographically. The complexes crystallize isotypically with one another in the monoclinic space group I2/a with eight formula units per unit cell. The metal atoms of the complex anions are tetrahedrally coordinated by the three nitrogen atoms of the N(SiMe₃)₂^– ligands and by the oxygen atom of the OSiMe₃^– ligand. With 172.4° for 1 a and 179.3° for 1 c the bond angles M–O–Si are practically linear. With ethynylbenzene in the presence of NaN(SiMe₃)₂ in tetrahydrofuran the trisamides M[N(SiMe₃)₂]₃ react under formation of the complexes [Na(THF)₃M{N(SiMe₃)₂}₃ · (C≡C–Ph)] with M = Ce ( 2 a ), Sm ( 2 b ), and Eu ( 2 c ), of which 2 b was characterized crystallographically (monoclinic, space group P2₁/n, Z = 4). 2 b forms an ion pair in which the terminal carbon atom of the C≡C–Ph^– ligand is connected with the samarium atom of the Sm[N(SiMe₃)₂]₃ group and the sodium ion is side-on connected with the acetylido group. According to the crystal structure determination (space group P2₁2₁2₁, Z = 4) [Na(THF)₆][Lu₂(μ-NH₂)(μ-NSiMe₃) · {N(SiMe₃)₂}₄] ( 3 ), which is formed as a by-product, consists of [Na(THF)₆]⁺ ions and dimeric anions, in which the lutetium atoms are connected to form a planar Lu₂N₂ four-membered ring via a μ-NH₂ bridge with average Lu–N distances of 227.2 pm and via a μ-NSiMe₃ bridge of average Lu–N distances of 218.5 pm. According to the crystal structure determination (space group P 1, Z = 1) [NaN(SiMe₃)₂(THF)]₂ ( 4 ) forms centrosymmetric dimeric molecules with Na–N distances of the Na₂N₂ four-membered ring of 239.9 pm and distances Na–O of the terminally bonded THF molecules which are 226.7 pm. The vinylic polymerization of methylmethacrylate (MMA) catalyzed by 1 c resulted in high molecular weight polymethylmethacrylate (PMMA) with moderate yields. The reaction of 1 a or 2 b with MMA did not give PMMA. Insoluble polynorbornene was obtained in low yields by reaction of norbornene/methylaluminoxane (MAO) with 1 a , 1 c , or 2 b . The ring opening polymerization of ϵ-caprolacton or δ-valerolacton catalyzed by 2 b resulted in corresponding polylactones in quantitative yields.     

Sc3+ Chloro and Alkyl Complexes Coordinated by Pincer NHC-Tethered Bis(phenolate) Ligands

Bis(phenolate) ligands with benzimidazole-2-ylidene ( L¹) and tetrahydropyrimidine-2-ylidene ( L² ) linkers proved to be suitable coordination environments for the synthesis of isolable Sc³⁺ chloro and alkyl complexes. The treatment of Sc(CH₂SiMe₃)₃(THF)₂ with equimolar amounts of [ L^1,2H₃ ] Cl afforded chloro complexes L^1,2ScCl ( solv ) ₂ (solv=THF, Py) in 76–85 % yields. L^1,2ScCl ( THF ) ₂ were also prepared by the salt metathesis reactions of ScCl₃ with [ L^1,2 ] Na₂ generated from [ L^1,2H₃ ] Cl and 3 equiv. of NaN(SiMe₃)₂ (−40 °C, THF) and isolated in somewhat lower yields (68–73 %). L²ScCl ( THF ) ₂ was subjected to the alkylation reaction with LiCH₂SiMe₃ affording alkyl derivative [ L²Sc ( CH₂SiMe₃ )] ₂ . This compound can be alternatively prepared by the subsequent reactions of [ L²H₃ ] Cl with equimolar amount of NaN(SiMe₃)₂ and Sc(CH₂SiMe₃)₃(THF)₂. In the dimeric alkyl compound [ L²Sc ( CH₂SiMe₃ )] ₂ , one of the phenoxide groups of the dianionic ligand is coordinated to one scandium center, while the second one features μ-bridging coordination with two metal centers.     

Lateral Metallation and Redistribution Reactions of Sodium Ferrates Containing Bulky 2,6-Diisopropyl-N-(trimethylsilyl)anilide Ligands

Alkali-metal ferrates containing amide groups have emerged as regioselective bases capable of promoting Fe−H exchanges of aromatic substrates. Advancing this area of heterobimetallic chemistry, a new series of sodium ferrates is introduced incorporating the bulky arylsilyl amido ligand N(SiMe₃)(Dipp) (Dipp=2,6-iPr₂-C₆H₃). Influenced by the large steric demands imposed by this amide, transamination of [NaFe(HMDS)₃] (HMDS=N(SiMe₃)₂) with an excess of HN(SiMe₃)(Dipp) led to the isolation of heteroleptic [Na(HMDS)₂Fe{N(SiMe₃)Dipp}]_∞ ( 1 ) resulting from the exchange of just one HMDS group. An alternative co-complexation approach, combining the homometallic metal amides [NaN(SiMe₃)Dipp] and [Fe{N(SiMe₃)Dipp}₂] induces lateral metallation of one Me arm from the SiMe₃ group in the iron amide furnishing tetrameric [NaFe{N(SiCH₂Me₂)Dipp}{N(SiMe₃)Dipp}]₄ ( 2 ). Reactivity studies support that this deprotonation is driven by the steric incompatibility of the single metal amides rather than the basic capability of the sodium reagent. Displaying synergistic reactivity, heteroleptic sodium ferrate 1 can selectively promote ferration of pentafluorobenzene using one of its HMDS arms to give heterotrileptic [Na{N(SiMe₃)Dipp}(HMDS)Fe(C₆F₅)]_∞ ( 4 ). Attempts to deprotonate less activated pyridine led to the isolation of NaHMDS and heteroleptic Fe(II) amide [(py)Fe{N(SiMe₃)Dipp}(HMDS)] ( 5 ), resulting from an alternative redistribution process which is favoured by the Lewis donor ability of this substrate.     

Syntheses and crystal structures of two copper(II) complexes derived from 2-bromo-4-chloro-6-[(2-morpholin-4-ylethylimino)methyl]phenol

Two new copper(II) complexes, [CuL₂] (1) and [Cu₂L₂(NCS)₂] · 2CH₃CN (2) (HL = 2-bromo-4-chloro-6-[(2-morpholin-4-ylethylimino)methyl]phenol), have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 was synthesized by reaction of HL with copper(II) acetate in methanol, while 2 was synthesized by adding ammonium thiocyanate to a methanol/acetonitrile (V : V = 2 : 1) solution of 1. Complex 1 crystallizes in the P2₁/n space group, and the thiocyanato-bridged dinuclear copper(II) complex, 2, crystallizes in the Pbcn space group. The Cu in 1 is four-coordinate square-planar with two imine N and two phenolate O atoms from two Schiff-base ligands. The Cu in 2 is five-coordinate square-pyramidal with NNO donor atoms of one Schiff-base ligand and one N atom of a bridging thiocyanate ligand defining the basal plane, and with one S atom of another bridging thiocyanate ligand occupying the apical position.     

Synthesis,X-ray crystal structure and magnetic study of a μ 1,5-dca bridged ferromagnetic dimeric copper(II) complex

Reaction of Cu(NO₃)₂ · 3H₂O, 1-(N-salicyalideneimine)-2-(N,N-dimethyl)-aminoethane (HL¹), LiClO₄, and sodium dicyanamide (Nadca) in aqueous medium affords a dimeric complex [Cu₂(L¹)₂ (μ_{1, 5}-dca)](ClO₄) (1). Single crystal X-ray analysis reveals that 1 is dinuclear with copper(II) ions bridged by a single dicyanamide group in end-to-end fashion. The coordination environment around copper(II) is square planar. Two nitrogens and oxygen of the tridentate Schiff-base ligand (HL¹) occupy three coordination sites of the square plane while the remaining site is occupied by the nitrogen of a terminal nitrile of the bridging dca. The nitrogen of the other terminal nitrile group of the μ_1,5-dca ligand connects a neighboring [CuL¹] unit to yield [Cu₂(L¹)₂(μ_1,5-dca)](ClO₄) (1). Variable temperature magnetic susceptibility measurements show that the magnetic interaction is ferromagnetic (J = 1.93 cm^?1). The results of a magnetic model are in good agreement with the experimental data.     

Disentangling steric and electronic factors in monomeric bis(2‐bromo‐4‐chloro‐6‐{[(2‐hydroxyethyl)imino]methyl}phenolato‐κ2N,O)copper(II)

The title compound, [Cu(C₉H₈BrClNO₂)₂], is a square‐planar complex. The potentially tridentate dibasic 2‐bromo‐4‐chloro‐6‐{[(2‐hydroxyethyl)imino]methyl}phenolate ligand coordinates in a trans‐bis fashion to the Cu^II centre via the imine N and phenolate O atoms. The Cu^II atom lies on the centre of inversion of the molecule. The potentially coordinating hydroxyethyl group remains protonated and uncoordinated, taking part in intermolecular hydrogen bonds with vicinal groups, leading to the formation of a two‐dimensional hydrogen‐bond network with sheets parallel to the (10) plane. Substituent effects on the crystal packing and coordination modes of the ligand are discussed.     

Transition Metal Complexes with Thiosemicarbazide-Based Ligands. Part 37.* Synthesis and Study of the first Thiosemi-Carbazide-Derived Copper(I) Complexes: Crystal Structure of [2-(Diphenylphosphino)Benzaldehyde Thiosemicarbazonato(−1)] Copper(I)-Nitrate-Methanol Solvate

Abstract

The preparation and physical characterization of two copper(I) complexes Cu(HL)NO₃ and [Cu(HL)₂]NO₃·MeOh formed with a newly synthesized tridentate [S,N,P] HL = 2-(diphenylphosphino)benzaldehyde thiosemicarbazone ligand and the crystal structure analysis of the latter have been carried out. An X-ray study of [Cu(HL)₂]NO₃·MeOH revealed a copper(I) ion coordinated tetrahedrally to S,N,P,P atoms donated by two HL ligands. One is tridentate [S,N,P], whereas the second HL ligand is monodentate, ligating only its phosphorus atom to the copper. The geometry around the four-coordinate Cu(I) is comparable with Cu{N,S,P,X} tetrahedra (X = N, P, or S) retrieved from the Cambridge Structural Database. In addition, with a restriction to Cu{N,P,X,X} (X = C,N,P) tetrahedra ‐ S is excluded ‐ ca. 60 structures against     

Neue ONS‐Liganden und ihre Zinkkomplexe mit Bezug zum Zinkenzym Alkoholdehydrogenase

New ONS Ligands and their Zinc Complexes with Relation to the Zinc Enzyme Alcoholdehydrogenase By ring opening of dimethyl thiirane with ethanolamine or by Schiff base condensation between salicylic aldehydes and 2‐mercaptoisobutylamine the tridentate ONS ligands H₂MIEA, H₂MIIMP, and H₂MIIMTP were obtained. The former yielded the zinc complex (MIEA)Zn(ethanolamine) ( 1 ) with a trigonal bipyramidal ZnO₂N₂S coordination. The latter two and Zn[N(SiMe₃)₂]₂ yielded the presumably dimeric complexes Zn(MIIMP) and Zn(MIIMTP) ( 2 a , b ). Benzoyl pyridine and phenylhydroxymethylpyridine as bidentate coligands L could be combined with H₂MIIMP in the complexes L · Zn(MIIMP) ( 3 , 4 ) whose ZnO₂N₂S coordination corresponds to that of 1 . Partial hydrolytic degradation led to the unusual trinuclear complex 5 which contains, inter alia, the condensation product of the salicylic aldimine and benzoyl pyridine as a ligand. The complexes obtained and the coordination patterns observed represent new structural analogies with the environment of zinc in the enzyme horse liver alcoholdehydrogenase.     

Unusual coordination features and self-assembly of a crown ether complex [Na2(2,3-naphtho-15-crown-5)2(NO3)][Cu(NO3)3(H2O)]

A novel supramolecular complex, [Na₂(2,3-naphtho-15-crown-5)₂(NO₃)][Cu(NO₃)₃(H₂O)] (1), has been prepared and characterized by X-ray single crystal diffraction. The complex crystallizes in the triclinic system, space group Pī, with a?=?11.233(6), b?=?13.342(7), c?=?16.601(8)?Å, α?=?89.836(7), β?=?79.132(8), γ?=?66.545(7)°, V?=?2234(2)?ų, Z?=?2 and final R ₁(wR ₂)?=?0.0467(0.1164). Novel coordination features and supramolecular architectures are found in the solid state of 1. Two [Na(2,3-naphtho-15-crown-5)]⁺ cations containing two different sodium coordination numbers (six and seven) are bridged by a tridentate nitrate group, to form a larger complex cation, [Na₂(2,3-naphtho-15-crown-5)₂(NO₃)], which is assembled into a novel 1D zigzag chain-like structure through aromatic C–H?···?π interactions.     

Synthesis,crystal structures and magnetic properties of two new nickel(II) complexes with α-amino acid Schiff base

Two nickel(II) complexes [Ni(napgly)(MeOH)] _n (1) and [Ni(napphe)(H₂O)₂(MeOH)] · H₂O (2), where the tridentate Schiff-base ligands H₂napgly and H₂napphe are condensed from 2-hydroxyl-1-naphthaldehyde with glycine and L-phenylalanine, respectively, were prepared and structurally characterized. In 1, two inversion-related Ni(II) ions were bridged by two O atoms from the phenolate groups of two napgly anions, forming a centrosymmetric dimeric unit which was further linked by carboxylate groups to give a two-dimensional network. Magnetic susceptibility studies performed on the complex revealed anti-ferromagnetic coupling between the metal centers. In 2, the crystal structures of the complex displayed a distorted octahedral coordination geometry in which the ONO-donor Schiff base was bonded to the metal. Intermolecular H-bonds linked the compound into a 2-D layer structure.     

Synthesis and Structural Characterization of Lanthanide Amides Stabilized by an N-Aryloxo Functionalized β-Ketoiminate Ligand

The synthesis and characterization of dimeric lanthanide amides stabilized by a dianionic N‐aryloxo functionalized β‐ketoiminate ligand are described in this paper. Reactions of 4‐(2‐hydroxy‐5‐tert‐butyl‐phenyl)imino‐2‐pentanone (LH₂) with Ln[N(SiMe₃)₂]₃(µ‐Cl)Li(THF)₃ in a 1:1 molar ratio in THF gave the dimeric lanthanide amido complexes [LLn{N(SiMe₃)₂}(THF)]₂ [Ln=Nd ( 1 ), Sm ( 2 ), Yb ( 3 ), Y ( 4 )] in good isolated yields. These complexes were characterized by IR spectroscopy, elemental analysis, and ¹H NMR spectroscopy in the case of complex 4 . The definitive molecular structures of complexes 1 , 3 , and 4 were determined. It was found that complexes 1 to 4 can initiate the ring‐opening polymerization of L‐lactide.     

New potentially tridentate amidinate ligand {o-MeOC6H4NC(Ph)N(SiMe3)}?. Synthesis and molecular structures of amidinate complexes of lithium [{o-MeOC6H4NC(Ph)N(SiMe3)}Li]2 and yttrium [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)2]2

The reaction of lithium silylamide [??o-MeOC₆H₄N(SiMe₃)}Li(OEt₂)]₂ with 2 equiv. of benzonitrile in THF at ??20 °C affords the lithium derivative of the new tridentate amidinate ligand [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}Li]₂. The X-ray diffraction study showed that this complex has a dimeric structure due to the coordination of the N atoms and the ether group of one amidinate ligand to different Li atoms. The reaction of anhydrous YCl₃ with the resulting complex in THF gives the monoamidinate complex [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}YCl₂(THF)₂]₂ regardless of the reagent ratio. The latter has a dimeric structure in the crystalline state as a result of the presence of two ??₂-bridging Cl atoms that link Y atoms. The ether groups of the amidinate ligands are not involved in the metal-ligand interaction.     

Synthesis and Structural Characterization of Alkali Metal Guanidinates

Reactions of 1,3-diisopropylcarbodiimide with alkali metal amides, MN（SiMe3）2 （M=Li or Na） in hexane or THF produced the alkali metal guanidinates { （i-PrN）2C [N（SiMe3）2]Li }2 （1） and { （i-PrN）2C[N（SiMe3）2]Na（THF） } 2 （2） in nearly quantitative yields. Both complexes 1 and 2 were well characterized by elemental analysis, IR spectra, ^1H and ^13C NMR spectra, and X-ray diffraction. It was found that the guanidinates adopt different coordination modes in these complexes.     

Synthesis and structures of 3-chloro-N′-(2-hydroxy-benzylidene)benzohydrazide and its oxovanadium(V) complex

A new Schiff-base 3-chloro-N ′ -(2-hydroxybenzylidene)benzohydrazide (H₂BBH) and its oxovanadium(V) complex [VO(BBH)(OCH₃)]₂ have been synthesized and characterized by elemental analysis, infrared (IR) spectra, and single-crystal X-ray determination. Both the ligand and the complex crystallized in the monoclinic space group P2₁ /c. The Schiff-base coordinates to V through the phenolate O, the imine N, and the enolic O. In the centrosymmetric dimeric oxovanadium(V) complex, the V atom is six-coordinate in an octahedral geometry. The bond lengths related to the donor atoms in the complex are different from those in the ligand. The coordination of the ligand to V is also supported by IR spectra.     

An unsymmetrical phosphonium diylide with a fluorenylidene subunit and its lithium complexes

The phosphonium ylide MePh₂P(flu) (3) (flu = C₁₃H₈, fluorenylidene) was conveniently prepared by reaction of Ph₂P(fluH) (1) (fluH = C₁₃H₉, fluorenyl) with iodomethane, followed by subsequent dehydrohalogenation of the resulting phosphonium salt [MePh₂P(fluH)]I (2) by potassium tert-butoxide. Compound 3 was further deprotonated by n-butyllithium, yielding the corresponding lithium complex [Li{CH₂PPh₂(flu)}(tmeda)] (4) in presence of N,N,N′,N′-tetramethylethylenediamine (tmeda). This mononuclear lithium compound contains the monoanionic chelating diylidic ligand. An exchange of the neutral bidentate tmeda by tridentate N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (pmdta) enforces a change in coordination mode. Consequently, the diylide is monodentate in [Li{CH₂PPh₂(flu)}(pmdta)] (5). Compounds 1–5 were characterized by NMR spectroscopy and single-crystal X-ray diffraction experiments.     

Coordination diversity in tin compounds with bis(benzoxazole)phenol as a polydentate ligand: Synthesis and crystal structure studies

Abstract

The reaction of 2,6-bis(benzoxazolyl)-4-tert-butylphenol (HL) with [ⁿBu_xSnCl_4?x] (x?=?0, 1) in 1:1 stoichiometry yielded the tin coordination complexes [(HL)SnⁿBu_xCl_4?x] [x?=?0 (1); x?=?1 (2)]. Deprotonation of HL was performed using reagents having groups with high basicity such as ⁿBuLi or [Sn{N(SiMe₃)₂}₂]. These basic reagents prompted the coordination of the ligand in its anionic form, yielding the complexes [(thf)₂Li(L)SnCl₄] (3) and [(L)Sn{N(SiMe₃)₂}] (4), respectively. The molecular structure of HL displayed an intramolecular hydrogen bond OH—N and a planar arrangement of the bis(benzoxazolyl)phenolic system. In the molecular structures of both complexes containing HL an intramolecular hydrogen bond of NH—O type was also present. The coordination of the ligand in either neutral or anionic form is described by a κO,κN chelate mode toward Sn. All complexes displayed bis(benzoxazolyl)phenolic moieties close to planar; the least planar system was observed in 4 that was also studied by DFT methods.     

SYNTHESIS AND X-RAY CRYSTAL STRUCTURE OF BIS (2-AMINOMETHYLAZIRIDINE)NICKEL(II) PERCHLORATE

Abstract

The structure of the big (2-aminomethylaziridine = azida)nickel(II) complex was determined by X-ray diffraction methods. The compound, [Ni(azida)₂](C1O₄)2, crystallizes in the triclinic space group P1, Z=l, with a = 7.3545(4), b = 8.5235(5), c = 6.2156(4)Å, α= 101.871(6). β = 103.217(6), γ= 111.283(4)°, and V= 335.07(5) ų. The crystal shows discrete centrosymmetncal [Ni(azida)]²⁺ units in which azida acts as bidentate chelating ligand through N aziridine and N amino atoms. Thus, Ni has a four-coordinate square-planar geometry with four nitrogens of azida. The aziridine ring is almost perpendicular to the coordination plane. The dihedral angle between the aziridine plane and the coordination plane is 75.28°.     

Supramolecular Cd(II) complexes with (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso): synthesis,X-ray structures,Hirshfeld surface analyses,and DFT study of [CdX2(2-pyimiso)2] (X = Cl or NCS)*

The paucity of coordination entities bearing (E)-N,N′-bis(heteroaryl)iminoisoindolines has prompted us to investigate coordination modes and supramolecular features of (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso), a versatile iminobis(pyridyl) ligand. In this article we report the synthesis, spectroscopic characterization and crystal structure analysis of two Cd(II) : 2-pyimiso (1?:?2) bis-adducts, [CdX₂(2-pyimiso)₂] [X = Cl (1) or NCS (2)]. Our X-ray structural results reveal that 1 exhibits distorted tetrahedral coordination (four-coordinate geometry index τ₄ = 0.92), whereas 2 displays six-coordinate Cd(II) and two four-membered chelate rings (bite angles = 52.5°), each comprising one Cd–N_py [2.247(2) Å] bond and one Cd?N_imine [2.809(21) Å] secondary interaction. Remarkably, in 2 each 2-pyimiso unit binds to Cd(II) according to an unusual bidentate coordination. The contributions of the Cd–N and Cd–Cl bond valences to the total metal valence for both 1 and 2 have been evaluated to confirm the coordination modes of 2-pyimiso, which can be interpreted in terms of Jørgensen’s principle of symbiosis. X-ray structure and Hirshfeld surface analyses have shown that the crystal structure of 1 is determined by two perpendicular 1-D chains formed by weak hydrogen bonds along the a- and c-axes, whereas the supramolecular architecture of 2 exhibits 2-D sheets parallel to the ab-plane interconnected by C–H?π interactions along the c-axis. A vibrational analysis of both products has been conducted at the DFT B3LYP-D3/LACV3P** level of calculation.     

Synthesis,Characterization and Spectral Studies of Triethanolamine Complexes of Metal Saccharinates. Crystal Structures of [Co(TEA)2](SAC)2 AND [Cu2(μ-TEA)2(SAC)2]·2(CH3OH)

The novel transition metal saccharinate complexes of triethanolamine (TEA) have been synthesized and characterized by elemental analyses, magnetic moments, UV-Vis and IR spectra. Mn(II), Co(II), Ni(II), Zn(II), Cd(II) and Hg(II) form mononuclear complexes of [M(TEA)₂](SAC)₂, where SAC is the saccharinate ion, while the Cu(II) complex is dimeric. The TEA ligand acts as a tridentate N,O,O'-donor ligand and one ethanol group is not involved in coordination. The SAC ion does not coordinate to the metal ions and is present as the counter-ion in the Mn(II), Co(II), Ni(II), Zn(II), Cd(II) and Hg(II) complexes, but coordinates to the Cu(II) ion as a monodentate ligand. The crystal structures of the [Co(TEA)₂](SAC)₂ and [Cu₂(μ-TEA)₂(SAC)₂]·2(CH₃OH) complexes were determined by single crystal x-ray diffraction. The Co(II) ion has a distorted octahedral coordination by two TEA ligands. The Cu(II) complex crystallizes as a dimethanol solvate and has doubly alkoxo-bridged centrosymmetric dimeric molecules involving two tridentate triethanolaminate (deprotonated TEA) and two monodentate SAC ligands. The geometry of each Cu(II) ion is a distorted square pyramid. Both crystal structures are stabilized by hydrogen bonds to form a three-dimensional network.     

Yttrium bis(alkyl) and bis(amido) complexes bearing N,O multidentate ligands. Synthesis and catalytic activity towards ring‐opening polymerization of L‐lactide

Methoxy‐modified β‐diimines HL ¹ and HL ² reacted with Y(CH₂SiMe₃)₃(THF)₂ to afford the corresponding bis(alkyl)s [L¹Y(CH₂SiMe₃)₂] ( 1 ) and [L²Y(CH₂SiMe₃)₂] ( 2 ), respectively. Amination of 1 with 2,6‐diisopropyl aniline gave the bis(amido) counterpart [L¹Y{N(H)(2,6‐iPr₂? C₆H₃)}₂] ( 3 ), selectively. Treatment of Y(CH₂SiMe₃)₃(THF)₂ with methoxy‐modified anilido imine HL ³ yielded bis(alkyl) complex [L³Y(CH₂SiMe₃)₂(THF)] ( 4 ) that sequentially reacted with 2,6‐diisopropyl aniline to give the bis(amido) analogue [L³Y{N(H)(2,6‐iPr₂? C₆H₃)}₂] ( 5 ). Complex 2 was “base‐free” monomer, in which the tetradentate β‐diiminato ligand was meridional with the two alkyl species locating above and below it, generating tetragonal bipyramidal core about the metal center. Complex 3 was asymmetric monomer containing trigonal bipyramidal core with trans‐arrangement of the amido ligands. In contrast, the two cis‐located alkyl species in complex 4 were endo and exo towards the O,N,N tridentate anilido‐imido moiety. The bis(amido) complex 5 was confirmed to be structural analogue to 4 albeit without THF coordination. All these yttrium complexes are highly active initiators for the ring‐opening polymerization of L ‐LA at room temperature. The catalytic activity of the complexes and their “single‐site” or “double‐site” behavior depend on the ligand framework and the geometry of the alkyl (amido) species in the corresponding complexes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5662–5672, 2007