Tris Complexes Research Articles

Antimony(III) Dithiocarbamates: Synthesis, Spectral, Theoretical and Biological Activities

Antimony(III) dithiocarbamate complexes tris(N,N-difurfuryldithiocarbamato-S,S′)antimony(III) (1) and tris(N-furfuryl-N-(2-phenylethyl)dithiocarbamato-S,S′)antimony(III) (2) have been synthesized and characterized by CHN analysis, FT-IR, 1H NMR, 13C NMR spectra and antimicrobial studies. The characteristic thioureide ν(C-N) bands occur at 1459 and 1469 cm-1 for complexes 1 and 2, respectively. 1H NMR and 13C NMR chemical shifts have been calculated using GIAO approach and the calculated chemical shifts shows good agreement with experiential shifts. The computational calculations of the antimony(III) complexes have been carried out by DFT/B3LYP using LANL2DZ basis set. The FMOs, MEP, Mulliken charge distribution and chemical activity parameters were calculated at the same level of theory. The antimicrobial activities of the antimony(III) complexes were assayed at the concentrations 400 and 800 μg/mL against four bacterial (Vibrio cholera, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli) and two fungal species (Candida albicans and Aspergillus niger) by Agar-well disc diffusion method.

Cation- and Anion-Mediated Supramolecular Assembly of Bismuth and Antimony Tris(3-pyridyl) Complexes.

The use of antimony and bismuth in supramolecular chemistry has been largely overlooked in comparison to the lighter elements of Group 15, and the coordination chemistry of the tripodal ligands [Sb(3-py)3] and [Bi(3-py)3] (L) containing the heaviest p-block element bridgehead atoms has been unexplored. We show that these ligands form a common hybrid metal–organic framework (MOF) structure with Cu(I) and Ag(I) (M) salts of weakly coordinating anions (PF6–, SbF6–, and OTf–), composed of a cationic substructure of rhombic cage (M)4(L)4 units linked by Sb/Bi–M bonding. The greater Lewis acidity of Bi compared to Sb can, however, allows anion···Bi interactions to overcome Bi–metal bonding in the case of BF4–, leading to collapse of the MOF structure (which is also seen where harder metals like Li+ are employed). This study therefore provides insight into the way in which the electronic effects of the bridgehead atom in these ligand systems can impact their supramolecular chemistry.

Luminescence behavior of PMMA films doped with Tb(III) and Eu(III) complexes

Novel hybrid systems based on the poly(methyl methacrylate) (PMMA) matrix and Eu(III) and Tb(III) tris(β-diketonates) complexes with 1,10-phenanthroline were synthesized and analyzed as light-conversion materials. Solutions of the Tb(III) and Eu(III) complexes doped into PMMA were spin-coated to fabricate films with various concentrations of luminophores. Long hydrocarbon substituents in the structure of complexes inhibit their crystallization. In turn, it allows to vary the luminophore content in a polymer matrix in a broader range and achieve the maximum of emission with higher concentrations of dopants. The addition of the Tb(III) complex to the system results in a 26% increase in the relative luminescence quantum yield of the Eu(III) ions due to an additional energy transfer from the Tb(III) compound. The results of this work illustrate that although the Eu(III) and Tb(III) complexes exhibit lower rate and efficiency of energy transfer than their well-known Tb(acac)3 and Eu(tta)3 analogues, the structural features of lanthanide complexes allow to efficiently dope a PMMA matrix with considerably larger amounts of luminophores. It offers broader application opportunities for the coordination Ln(III) compounds as polyfunctional materials for optics and optoelectronics.

Synthesis, structure and properties of tris(hydroxymethyl)aminomethane complexes with biogenic metal salts

New coordination compounds - analogues of hydrometallatranes, characterized by FT-IR spectroscopy, mass spectrometry and elemental analysis, were synthesized by the interaction of tris(hydroxymethyl)aminomethane (TRIS) with Cu(II), Co(II), Ni(II) and Zn(II) salts of carboxylic acids. The crystal structure of TRIS complex with Cu(II) cinnamate was determined by X-ray diffraction. The structural parameters and gap energy for this complex have been calculated by the DFT method. The thermal analysis data for new TRIS complexes are presented. The effect of some TRIS hydrometallatranes, as well as TEA and TPA hydrometallatranes on the growth of corrosion-aggressive thionic bacteria was studied.

Pentamethylcyclopentadienyl Complexes of Cerium(IV): Synthesis, Reactivity, and Electrochemistry.

Treatment of Cp*2CeCl2K(THF) with alkali-metal alkoxides and siloxides in the presence of hexachloroethane generates the monomeric bis(pentamethylcyclopentadienyl) cerium(IV) complexes Cp*2Ce(OR)2 (Cp* = C5Me5; R = Et, iPr, CH2tBu, tBu, SiMe3, or SiPh3). Large substituents R trigger ligand scrambling to half-sandwich complexes Cp*Ce(OR)3, which could be isolated for R = tBu and SiPh3. Similar reactions with sodium aryloxide NaOAr (OAr = OC6H3iPr2-2,6) led to Cp*2Ce(OAr)Cl. Treatment of tris(cyclopentadienyl) complexes CpR3CeCl (CpH = Cp = C5H5; CpMe = C5H4Me) with NaOAr afforded CpMe2Ce(OAr)2 and Cp3Ce(OAr). The cerium(IV) complexes display a pseudotetrahedral geometry in the solid state. Cyclic voltammetry revealed mostly chemically reversible as well as electrochemically quasi-reversible redox processes with potentials ranging from -0.84 to -1.61 V versus Fc/Fc+. Switching from sandwich to half-sandwich complexes decreased the electrochemical potentials drastically, showing better stabilization of the cerium(IV) center in the case of Cp*Ce(OR)3 than in the case of Cp*2Ce(OR)2. Enhanced stabilization of the cerium +IV oxidation state could be further demonstrated in the series alkoxy > siloxy > aryloxy as well as C5Me5 > C5HMe4.

Magnesium(I) Reduction of CO and N2 Complexes of Cummins’ Molybdenum(III) Tris(anilide), [Mo(L){N(Ar’)But}3] (L=CO or N2; Ar’=3,5‐dimethylphenyl)

AbstractReductions of the in situ generated CO and N2 complexes of Cummins’ molybdenum(III) tris(anilide) complex, viz. [Mo(L){N(Ar’)But}3] (L=CO or N2, Ar’=3,5‐dimethylphenyl), using a dimagnesium(I) compound, [{(MesNacnac)Mg}2] (MesNacnac=[HC(MeCNMes)2]−, Mes=mesityl), are reported. Reduction of [Mo(CO){N(Ar’)But}3] afforded a mixture of products, three of which were isolated in low yield and crystallographically characterized. These were a molybdenum(II) tris(carbamoyl) complex, [(MesNacnac)Mg{μ‐(O=)[But(Ar’)N]C}3Mo(CO)3] 1, a magnesium(II) carbamate, [{(MesNacnac)Mg[μ‐O2CN(Ar’)But]}2] 2, and the 1,3‐diamino‐1,2,3‐trione, But(Ar’)NC3(=O)3N(Ar’)But 3. The mechanisms of formation of these products are speculated upon. The reduction of [Mo(N2){N(Ar’)But}3] with [{(MesNacnac)Mg}2], in the presence of the N‐heterocyclic carbene, :C{N(Me)C(Me)}2 TMC, gave the heterobimetallic molybdenum(II) diazenido complex, [(MesNacnac)(TMC)Mg(μ‐N2)Mo{N(Ar’)But}3] 4, in a low‐moderate isolated yield. Reaction of this with chlorotrimethylsilane afforded an essentially quantitative yield of the known silyldiazenido complex, [(Me3SiN2)Mo{N(Ar’)But}3] 5.

Cyclopentadienyl lanthanide borohydrides derived from the unsubstituted cyclopentadienyl ligand. Unprecedented structural diversity and ε-caprolactone polymerization

A series of mono-, bis- and tris(cyclopentadienyl) complexes of La, Nd and Tb with borohydride ligand were synthesized and structurally characterized. Various structural types of complex anions and cations containing cyclopentadienyl and borohydride ligands in the coordination sphere of Ln3+ have been studied by single-crystal X-ray diffraction. Five different structural types of Cp-lanthanide borohydrides were found for neodymium: {CpNd(BH4)2} in [(CpNd(BH4)2(THF)2] (2Nd); {Cp2Nd(BH4)2}− in [Cp2Nd(BH4)2][Na(18-crown-6)(THF)2] (3Nd); {Cp2Nd(BH4)} in [Cp2Nd(BH4)(THF)] (4Nd); {CpNd(18-crown-6)(BH4)}+ in [Cp2Nd(BH4)2]2[CpNd(18-crown-6)(BH4)][Na(18-crown-6)(THF)2] (6Nd); {Cp3Nd(BH4)}− in [Cp3Nd(BH4)][Na(18-crown-6)(THF)2] (8Nd). Complex anions {Cp2Nd(BH4)2}− and {Cp3Nd(BH4)}− are able to replace each other in the crystal lattice. Mono- and bis(cyclopentadienyl)borohydride complexes of neodymium effectively initiate ε-caprolactone polymerization.

Influence of Divalent Cations in the Protein Crystallization Process Assisted by Lanthanide-Based Additives.

The use of lanthanide complexes as powerful auxiliaries for biocrystallography prompted us to systematically analyze the influence of the commercial crystallization kit composition on the efficiency of two lanthanide additives: [Eu(DPA)3]3- and Tb-Xo4. This study reveals that the tris(dipicolinate) complex presents a lower chemical stability and a strong tendency toward false positives, which are detrimental for its use in a high-throughput robotized crystallization platform. In particular, the crystal structures of (Mg(H2O)6)3[Eu(DPA)3]2·7H2O (1), {(Ca(H2O)4)3[Eu(DPA)3]2}n·10nH2O (2), and {Cu(DPA)(H2O)2}n (3), resulting from spontaneous crystallization in the presence of a divalent alkaline-earth cation and transmetalation, are reported. On the other hand, Tb-Xo4 is perfectly soluble in the crystallization media, stable in the presence of alkaline-earth dications, and slowly decomposes (within days) by transmetalation with transition metals. The original structure of [Tb4L4(H2O)4]Cl4·15H2O (4) is also described, where L represents a bis(pinacolato)triazacyclononane ligand. This paper also highlights a potential synergy of interactions between Tb-Xo4 and components of the crystallization mixtures, leading to the formation of complex adducts like {AdkA/Tb-Xo4/Mg2+/glycerol} in the protein binding sites. The observation of such multicomponent adducts illustrated the complexity and versatility of the supramolecular chemistry occurring at the surface of the proteins.

Rare Earth Metal Complexes Supported by a Tripodal Tris(amido) Ligand System Featuring an Arene Anchor

A new tripodal tris(amido) ligand system featuring an arene anchor was developed and applied to the coordination chemistry of rare earth metals. Two tris(amido) ligands with a 1,3,5-triphenylbenzene backbone were prepared in two steps from commercially available reagents on a gram scale. Salt metathesis and alkane elimination reactions were exploited to prepare mononuclear rare earth metal complexes in moderate to good yields. For salt metathesis reactions, while metal tribromides yielded neutral metal tris(amido) complexes, metal trichlorides led to the formation of ate complexes with an additional chloride bound to the metal center. The new compounds were characterized by X-ray crystallography, elemental analysis, and 1H and 13C nuclear magnetic resonance spectroscopy. The rare earth metal complexes exhibit a trigonal planar coordination geometry for the [MN3] fragment in the solid state rather than a trigonal pyramidal geometry, commonly observed for rare earth metal tris(amido) complexes such as M[N(SiMe3)2]3. Moreover, the arene anchor of the tripodal ligands is engaged in a nonnegligible interaction with the rare earth metal ions. Density functional theory calculations were performed to gain insight into the bonding interactions between the tripodal ligands and the rare earth metal ions. While LUMOs of these rare earth metal complexes are mainly π* orbitals of the arene with a minor component of metal-based orbitals, HOMO-15 and HOMO-16 of a lanthanum complex show that the arene anchor serves as a π donor to the trivalent lanthanum ion.

Elucidation of Thorium Redox-Active Ligand Complexes: Evidence for a Thorium-Tri(radical) Species.

A series of thorium(IV) complexes featuring the redox-active 4,6-di-tert-butyl-N-(2,6-di-isopropylphenyl)-o-iminobenzoquinone (dippiq) ligand family have been synthesized and characterized. The neutral iminoquinone ligand was used to generate Th(dippiq)Cl4(dme)2 (1-iq) and Th(dippiq)2Cl4 (2-iq), both of which show dative bonds between the thorium(IV) ion and the ligands. One electron reduction of the ligand forms the unique tris(iminosemiquinone) complex, Th(dippisq)3Cl (3-isq), which features a radical in each ligand. Further reduction furnishes the amidophenolate species, Th(dippap)3]K2(THF)2 (4-ap), which has the ligands in their dianionic form. Attempts to sequester the potassium ions with cryptand resulted in the [Th(dippap)3K][K(crypt)] (4-ap mono crypt) and [Th(dippap)3][K(crypt)]2 (4-ap crypt) species. A bis(amidophenolate) complex was accessed by incorporating bulky triphenylphosphine oxide (OPPh3) ligands to generate Th(dippap)2(OPPh)3 (5-ap). Spectroscopic and structural characterization of each derivative established the +4 oxidation state for thorium with redox chemistry occurring at the ligands rather than the thorium ion. The reported 3-isq complex is unprecedented as it is the first tri(radical) thorium complex with the highest reported magnetic moment for a thorium species as characterized by SQUID magnetometry.

A modular platform based on electrospun carbon nanofibers and poly(N‐isopropylacrylamide) hydrogel for sensor applications

Modular sensor platforms are a fashion approach that allows the use of advanced materials to promote the evolution of portable electrochemical sensors. A modular platform building by the combination of carbonized poly(acrylonitrile) electrospun mat (C‐PAN; fiber diameter ca. 300 nm) and a poly(N‐isopropylacrylamide; PNIPAm) hydrogel was assayed. The individual components of the platform were physicochemically characterized before assembling. The swelling behavior and the capacity of sorption of a redox complex tris(1,10‐phenanthroline)iron(II) of the polymeric hydrogel were evaluated. Moreover, the morphological aspects of the electrospun fibers before and after carbonization were analyzed. Finally, cyclic voltammetry and chronocoulometry experiments were performed to analyze the electrochemical performance of the modular platform. In this work, we demonstrated that the platform takes advantage of the3D structure of the electrospun mat and the selective sorption of the hydrogel for the electrochemical sensing target analyte. The iron sensing using its complexation into the tris(1,10‐phenanthroline)iron(II) redox complex was assessed by differential pulse voltammetry (DPV). The anodic peak current showed a linear relation versus iron complex concentration in the range of 10–80 μmol L−1 with a detection limit of 0.103 μmol L−1. All the results herein presented suggest that a synergistic combination of large surface area carbon fiber electrodes and ion retaining hydrogel has been achieved.

Crystalline Hydrogen-Bonding Networks and Mixed-Metal Framework Materials Enabled by an Electronically Differentiated Heteroditopic Isocyanide/Carboxylate Linker Group.

Mixed-metal solid-state framework materials are emerging candidates for advanced applications in catalysis and chemical separations. Traditionally, the syntheses of mixed-metal framework systems rely on postsynthetic ion exchange, metalloligands, or metal-deposition techniques for the incorporation of a second metal within a framework material. However, these methods are often incompatible with the incorporation of low-valent metal centers, which preferentially bind to electronically "soft" ligands according to the tenets of hard/soft acid/base theory. Here we present the electronically differentiated isocyanide/carboxylate heteroditopic linker ligand 1,4-CNArMes2C6H4CO2H (TIBMes2H; TIB = terphenyl isocyanide benzoate; ArMes2 = 2,6-(2,4,6-Me3C6H2)2C6H2), which is capable of selective binding of low-valent metals via the isocyano group and complexation of hard Lewis acidic metals through the carboxylate unit. This heteroditopic ligand also possesses an encumbering m-terphenyl backbone at the isocyanide function to foster coordinative unsaturation. The treatment of TIBMes2H with [Cu(NCMe)4]PF6 in a 3:1 ratio results in preferential binding of the isocyanide group to the Cu(I) center as assayed by multinuclear NMR and IR spectroscopies. IR spectroscopy also provides strong evidence for the formation of a copper(I) tris(isocyanide) complex, wherein the carboxylic acid group remains unperturbed. The addition of TIBMes2 to [Cu(NCMe)4]PF6 in a 4:1 ratio results in crystallization of the hydrogen-bonding network, [Cu(TIBMes2H)4]PF6, in which the formation of R22(8) hydrogen bonds results in a 7-fold interpenetrated diamondoid lattice structure. The preassembly of a copper(I) tris(isocyanide) complex using TIBMes2H, followed by deprotonation and the introduction of ZnCl2, generates a novel and unusual zwitterionic solid-state phase (denoted as Cu/Zn-ISOCN-5; ISOCN = isocyanide coordination network) consisting of a coordinatively unsaturated [Cu(CNR)3]+ cationic secondary building unit (SBU) and an anionic, paddlewheel-type Zn(II)-based SBU of the formulation [Cl2Zn2(O2CR)3]-. Inductively coupled plasma mass spectrometry analysis provided firm evidence for a 2:1 Zn-to-Cu ratio in the network, thereby indicating that the isocyanide and carboxylate groups selectively bind soft and hard Lewis acidic metal centers, respectively. The extended structure of Cu/Zn-ISOCN-5 is a densely packed, noninterpenetrated AB-stacked layer network with modest surface area. However, it is thermally robust, and its formation and compositional integrity validate the use of an electronically differentiated linker for the formation of mixed-metal frameworks incorporating low-valent metal centers.

Complex of tris(2-hydroxyethyl)amine with zinc bis[(2-methylphenoxy)acetate] as an aortic cholesterol esterase inhibitor in the experiment

Complex of tris(2-hydroxyethyl)amine with zinc bis[(2-methylphenoxy)acetate] as an aortic cholesterol esterase inhibitor in the experiment

Complex of tris(2-hydroxyethyl)amine with zinc bis(2-methylphenoxyacetate) as an inhibitor of the acid lipase of the aortic intima

Complex of tris(2-hydroxyethyl)amine with zinc bis(2-methylphenoxyacetate) as an inhibitor of the acid lipase of the aortic intima

Facilitating the Ferration of Aromatic Substrates through Intramolecular Sodium Mediation.

Exploiting cooperative effects between Na and FeII centres present in tris(amide) ferrate complexes has led to the chemoselective ferration of pentafluorobenzene, benzene, toluene, anisole, and pyridine being realised at room temperature. The importance of this bimetallic partnership is demonstrated by neither the relevant sodium amide (NaHMDS or NaTMP) nor the FeII amide Fe(HMDS)2 efficiently metallating these substrates under the conditions of this study. By combining NMR studies with the isolation of key intermediates and DFT calculations, we offer a possible mechanism for how these reactions take place, uncovering a surprising reaction pathway in which the metals cooperate in a synchronised manner. Although the isolated products are formally the result of Fe‐H exchange, theoretical calculations indicate that the aromatic substrates undergo Na‐H exchange followed by fast intramolecular transmetallation to Fe, thus stabilizing the newly generated aryl fragment.

Photophysical Properties of Simple Palladium(0) Complexes Bearing Triphenylphosphine Derivatives.

Pd(0) complexes with monodentate phosphine ligands, [Pd(P)n] (n = 3, 4), are well-known catalysts. However, the nature of the Pd(0) complex, especially the basic photophysical properties of the Pd(0) complexes, has not been extensively explored. In this work, we measured the general photophysical properties and crystal structures of Pd(0)-bearing PPh3 derivatives in the solid state and in solution. In the solid state, four-coordinated Pd(0) complexes exhibited blue-yellow emission. On the other hand, three-coordinated Pd(0) complexes displayed yellow-orange emission. In solution, orange emission of three-coordinated complexes was observed, and prompt fluorescence was detected using time-resolved emission spectroscopy, which suggests a thermally activated delayed fluorescence mechanism. Density functional theory (DFT) and time-dependent DFT calculations show that the difference in the transition mechanism between the [Pd(PPh3)4] and [Pd(PPh3)3] complexes explains the different emission colors. The emitting states of both complexes have metal-to-ligand charge-transfer character, but the metal-centered d → p transition is considerably incorporated for emission of the tris complex.

Iron-Based, Symmetric, Non-Aqueous Redox Flow Battery

The redox flow battery (RFB) is a promising technology for the long-duration storage of energy from domestic- to utility-scale. A RFB stores charge in a liquid electrolyte that is charged and discharged in an electrochemical cell reactor. Since storage and reaction site are separated, energy and power of the system can be scaled independently via electrolyte tank and cell stack dimensions. Iron as one of earth’s most abundant elements is an attractive active material, especially in symmetric RFBs using the same electrolyte on both negative and positive side of the battery. One way to realize such a system is by combining iron with redox-active ligands in non-aqueous solvents.[1],[2] We study the iron tris(2,2’-bipyridine) complex which shows a metal-centred reversible oxidation and three ligand-based reductions that are solvent-dependent.[3] The influence of electrolyte composition on charge and discharge reactions as well as on viscosity and conductivity is further investigated. Charge-discharge cycling experiments are carried out in 3-electrode H-cell and flow cell setups. We determine failure modes for the positive side due to electrode kinetics and for the negative side due to solubility changes. We propose improvements to this non-aqueous RFB system based on the selection of electrode materials and cycling conditions.[1] J. Mun et al., J. Electrochem. Soc. 2018, 165, 215-219.[2] C. X. Cammack et al., DaltonTrans . 2021, 50, 858.[3] D. M. Cabral, P. C. Howlett, D. R. MacFarlane, Electrochim. Acta 2016, 220, 347-353.

Ti(fpin)3]2−: a structurally characterized transition metal tris(perfluoropinacolato) complex

AbstractThe reaction of TiCl3 ⋅ 3THF with perfluoropinacol (H2fpin), triethylamine and silver nitrite in acetonitrile yielded in the formation of the first tris(perfluoropinacolato) complex with a transition metal, (HNEt3)3[TiIV(fpin)3]NO2 (1). The compound was fully characterized with IR and UV‐vis spectroscopy as well as elemental analysis and single crystal X‐ray diffraction. The structure of 1 is compared with that of known homoleptic titanium(IV) compounds and the only other structurally resolved tris(perfluoropinacolato)metallate, the stannate(IV) (HNEt3)2[Sn(fpin)3] ⋅ 2acetone.

Tris(Butadiene) Compounds versus Butadiene Oligomerization in Second-Row Transition Metal Chemistry: Effects of Increased Ligand Fields.

The geometries, energetics, and preferred spin states of the second-row transition metal tris(butadiene) complexes (C4H6)3M (M = Zr–Pd) and their isomers, including the experimentally known very stable molybdenum derivative (C4H6)3Mo, have been examined by density functional theory. Such low-energy structures are found to have low-spin singlet and doublet spin states in contrast to the corresponding derivatives of the first-row transition metals. The three butadiene ligands in the lowest-energy (C4H6)3M structures of the late second-row transition metals couple to form a C12H18 ligand that binds to the central metal atom as a hexahapto ligand for M = Pd but as an octahapto ligand for M = Rh and Ru. However, the lowest-energy (C4H6)3M structures of the early transition metals have three separate tetrahapto butadiene ligands for M = Zr, Nb, and Mo or two tetrahapto butadiene ligands and one dihapto butadiene ligand for M = Tc. The low energy of the experimentally known singlet (C4H6)3Mo structure contrasts with the very high energy of its experimentally unknown singlet chromium (C4H6)3Cr analog relative to quintet (C12H18)Cr isomers with an open-chain C12H18 ligand.

Synthesis and characterization of β-diketiminato lanthanide amide complexes and their catalytic activity toward L-lactide polymerization

Amine elimination between lanthanide tris(amide) complexes Ln[N(TMS)2]3(μ-Cl)Li(THF)3 (TMS = SiMe3) and 1 equiv. of β-diketimine [CH3CN(C6H4OMe-o)CHCN(C6H4-iPr2-2,6)CH3]H (BDI-H) in toluene or THF at room temperature afforded β-diketiminato lanthanide bis(amide) complexes (BDI)Ln[N(TMS)2]2 (Ln = Sm (1), Yb (2)) in 86-89% isolated yields, while the same reaction was conducted in toluene at 110 °C gave the unexpected product [(BDI’)SmN(TMS)2]2 (BDI’ = CH3CN(C6H4O-o)C(CH3)CN(C6H4-iPr2-2,6)CH3) (3) in 40% yield. In contrast, treatment of lanthanide tris(amide) complex with a larger metal Nd[N(TMS)2]3(μ-Cl)Li(THF)3 with 1 equiv of BDI-H in toluene, whether at 110 °C or at room temperature, produced exclusively only β-diketiminato neodymium bis(amide) complex (BDI)Nd[N(TMS)2]2 (4). These lanthanide metal complexes were characterized by elemental analysis, and structurally authenticated by single crystal X-ray diffraction. It was found that all these lanthanide amide complexes were active for the ring-opening polymerization of L-lactide.