Synthesis and investigations of mixed-ligand lanthanide complexes with N,N′-dipyrrolidine-N′′-trichloracetylphosphortriamide, dimethyl-N-trichloracetylamidophosphate, 1,10-phenanthroline and 2,2′-bipyrimidine

Crystal structure of tetra-phenyl phosphate tetra-kis-[dimethyl (2,2,2-tri-chloro-acet-yl)phos-pho-ramidato]lutetium(III), PPh4[LuL4]

A lutetium(III) complex based on the anion of the ligand dimethyl (2,2,2-tri-chloro-acet-yl)phospho-ramidate (HL) and tetra-phenylphosphonium, of composition PPh4[LuL 4] (L = CAPh = carbacyl-amido-phosphate), or (C24H20)[Lu(C4H6Cl3NO4P)4], has been synthesized and structurally characterized. The X-ray diffraction study of the compound revealed that the lutetium ion is surrounded by four bis-chelating CAPh ligands, forming the complex anion [LuL 4]- with a coordination number of 8[O] for LuIII, while PPh4 + serves as a counter-ion. The coordination geometry around the Lu3+ ion was determined to be a nearly perfect triangular dodeca-hedron. The complex crystallizes in the monoclinic crystal system, space group P21/c, with four mol-ecules in the unit cell. Weak hydrogen bonds O⋯HC(Ph), Cl⋯HC(Ph) and N⋯HC(Ph) are formed between the cations and anions. For a comparative study, HL-based structures were retrieved from the Cambridge Structural Database (CSD) and their geometries and conformations are discussed. A Hirshfeld surface analysis was also performed.

Blue-Emitting Zero-Dimensional Inorganic-Organic Hybrids Constructed from Beta-Diketonate Ligands and Bulky Organic Cations

Two zero-dimensional inorganic-organic hybrids, namely, [C₄mim][Cd(TCDPPA)₃] (1) and [C₄mpy][Cd(TCDPPA)₃] (2), where (TCDPPA)^- = 2,2,2-trichloro-N-(di(pyrrolidin-1-yl)phosphoryl)acetamide, (C₄mim)⁺ = 1-butyl-3-methylimidazolium, and (C₄mpy)⁺ = 1-butyl-4-methylpyridinium, have been synthesized via metathesis reactions and characterized systematically. These ionic cadmium-containing inorganic-organic hybrid compounds are assembled from a bulky organic cation and a complex anion constructed from the chelation of three TCDPPA ligands to one cadmium ion. These compounds possess wide band gaps and emit in the deep-blue region intensely with a quantum yield as high as 34.04%. The success of this work provides a new method for the design and fabrication of high-efficiency blue-emitting materials.

New luminescent lanthanide tetrakis - complexes NEt4[LnL4] based on dimethyl-N-benzoylamidophosphate

The new lanthanide dimethyl-N-benzoylamidophosphate (HL) based tetrakis-complexes NEt 4 [LnL 4 ] (Ln 3+ = La, Nd, Sm, Eu, Gd, Tb, Dy) are reported. The complexes are characterized by means of NMR, IR, absorption, and luminescent spectroscopy as well as by elemental, X-Ray, and thermal gravimetric analyses. The phenyl groups of the four ligands of the complex anion are directed towards one side, while the methoxy groups are directed in the opposite side, which makes the complexes under consideration structurally similar to calixarenes. The effect of changing the alkali metal counterion to the organic cation NEt 4 + on the structure and properties of the tetrakis-complex [LnL4]- is analyzed. The complexes exhibit bright characteristic for respective lanthanides luminescence. Rather high intensity of the band of 5 D 0 → 7 F 4 transition, observed in the luminescence spectrum of NEt 4 [EuL 4 ], is discussed based on theoretical calculations.

Synthesis and Characterization of Anionic Lanthanide(III) Complexes with a Bidentate Sulfonylamidophosphate (SAPh) Ligand

A series of new anionic lanthanide(III) complexes with the general formula NEt₄[LnL₄] (1-Ln; HL = dimethyl[(4-methylphenyl)sulfonyl]amidophosphate; Ln = La, Nd, Eu), were synthesized and characterized by IR, UV-vis, and NMR spectroscopies, the differential scanning calorimetry method, thermogravimetric and X-ray analysis, and photoluminescence measurements. Single-crystal structures of NEt₄[EuL₄] (1-Eu) were determined at 293 and 100 K and evidenced the single-crystal-to-single-crystal phase transition. Both phases are in the monoclinic crystal system in centrosymmetric groups of the same Laue class. The room temperature structure is in C2/c (No. 15), while low-temperature structure is in the P2₁/c (No. 14) space groups. The coordination environment geometry around the central europium(III) ion is a distorted square antiprism in both polymorphs, while the peripheral methoxy and tolyl groups show different orientations. This phenomenon indicates the occurrence of a thermally driven second-order phase transition during the cooling-heating process. The europium(III) complex exhibits an unusual emission spectrum, clearly dominated by the ⁵D₀-⁷F₄ bands, and an emission decay time equaling 3.5 ms, being among the highest values known for europium coordination compounds.

A Chiral Bipyrimidine-Bridged Dy2 SMM: A Comparative Experimental and Theoretical Study of the Correlation Between the Distortion of the DyO6N2 Coordination Sphere and the Anisotropy Barrier

Chiral bipyrimidine-bridged dinuclear Ln^III complexes of general formula [(μ-bipym){((+)-tfacam)₃Ln}₂] and [(μ-bipym){((-)-tfacam)₃Ln}₂], have been prepared from the assembly of Ln(AcO)₃·nH₂O (Ln^III = Dy, Gd), (+)/(−)-3-(trifluoroacetyl)camphor enantiopure ligands ((+)/(-)-Htfacam) and bipyrimidine (bipym). The structure and chirality of these complexes have been supported by single-crystal X-Ray diffraction and circular dichroism. The study of the magnetic properties of the Gd^III complexes revealed a very weak antiferromagnetic interaction between the Gd^III ions through the bipyrimidine bridging ligand. Ab initio CASSCF calculations indicated that the ground Kramers doublet (KD) of both Dy^III centers is almost purely axial with the anisotropy axis located close to the two tfacam⁻ligands at opposite sides of each Dy^IIIatom, which create an axial crystal field. In keeping with this, ac dynamic measurements indicated slow relaxation of the magnetization at zero field with U_eff = 55.1 K, a pre-exponential factor of τ_o = 2.17·10⁻⁶ s and τ_QTM = 8 μs. When an optimal dc field of 0.1 T is applied, QTM is quenched and U_eff increases to 75.9 K with τ_o = 6.16 × 10⁻⁷ s. The DyN₂O₈ coordination spheres and SMM properties of [(μ-bipym){((+)-tfacam)₃Ln}₂] and their achiral [(Dy(β-diketonate)₃)₂(μ-bpym)]analogous have been compared and a magneto-structural correlation has been established, which has been supported by theoretical calculations. In contrast to the Gd^III compounds, the magnetic exchange interaction between the Dy^III ions has been calculated to be very weak and, generally, ferromagnetic in nature. Relaxation mechanisms for [(μ-bipym){((+)-tfacam)₃Ln}₂] and previously reported analogous have been proposed from ab initio calculations. As the magnetic exchange interaction found to be very weak, the observed magnetization blockade in these systems are primarily dictated by the single ion anisotropy of Dy^III ions.

Lanthanide mixed-ligand complexes of the [Ln(CAPh)3(Phen)] and [LaxEu1-x(CAPh)3(Phen)] (CAPh = carbacylamidophosphate) type. A comparative study of their spectral properties

A series of complexes Ln(Pip)3(Phen) (Ln(iii) = La, Ce-Nd, Sm-Lu, Y; HPip (CAPh type ligand) = 2,2,2-trichloro-N-(dipiperidin-1-yl-phosphoryl)acetamide, Phen = 1,10-phenanthroline) has been synthesized. The lanthanum(iii) doped europium(iii) complexes ([LaxEu1-x(Pip)3(Phen)], x = 0.99, 0.95, 0.50) have been obtained by the co-crystallization method. The complexes have been characterized by means of X-ray diffraction, IR, (1)H and (31)P-NMR and absorption spectroscopy. Emission and excitation luminescence spectra were recorded at 295 and 77 K. The lifetime values (τ) for the emission of all europium complexes were determined. The (5)D0 luminescence quantum efficiency is 73-89%. The symmetries of the nearest europium surrounding in pure and doped complexes were evaluated from the Stark splitting of (5)D0-(7)FJ transitions. Crystal structures of [Ln(Pip)3(Phen)] (Ln = Nd (1), Eu (2) and Tb (3)) have been determined. Lattice parameters of the [Ln(Pip)3(Phen)] (Ln = Tb, Yb) and the doped [LaxEu1-x(Pip)3(Phen)] (x = 0.99, 0.95, 0.50) complexes have been measured. The presence of four polymorphs within a number of rare earth elements has been estimated: two in triclinic (Ln1 = La, Nd; Ln2 = Eu), one in the monoclinic (Ln3 = Tb) and one in the rhombic (Ln4 = Tb, Yb) symmetry. Complex 3 can be obtained in two crystal modifications: monoclinic and orthorhombic ones.

N,N'-Dimethyl-N''-(trichloroacet-yl)phospho-ramide

In the title compound, C4H9Cl3N3O2P or CCl3C(O)NHP(O)(NHCH3)2, the P atom has a strongly distorted tetra-hedral geometry due to the formation of intermolecular strong hydrogen bonds involving the N atoms. In the crystal, N-H⋯O=P and N-H⋯O=C hydrogen bonds connect the mol-ecules into a two-dimensional array parallel to (100). An intra-molecular P⋯O contact [P⋯O = 2.975 (3) Å] is observed. The CCl3 group is rotationally disordered, with occupancies of 0.60 (3) and 0.40 (3).

MethylN-(dimethoxyphosphoryl)carbamate

In the title compound, CH₃OC(O)NHP(O)(OCH₃)₂, the P atom has a slightly distorted tetra­hedral configuration. The mixed imide moiety can be described as cisoid–transoid in which the two opposing dipoles (P=O and C=O) are oriented with a O=C⋯P=O torsion angle of 150.88(18)°. In the crystal, molecules are linked by pairs of N—H⋯O hydrogen bonds, forming inversion dimers.

N,N'-Dicyclo-hexyl-N''-(3-fluoro-benzo-yl)-N,N'-dimethyl-phospho-ric triamide

In the title compound, C₂₁H₃₃FN₃O₂P, the P atom has a distorted tetra­hedral environment and the N atoms display geometries consistent with a model of sp² hybridization (with bond-angle sums for the tertiary N atoms of 357.8 and 358.7°). The phosphoryl and carbonyl groups are anti with respect to each other. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R₂²(8) loops.

The Utility of 2,2′-Bipyrimidine in Lanthanide Chemistry: From Materials Synthesis to Structural and Physical Properties

This paper reviews the recent investigations undertaken on the use of 2,2′-bipyrimidine (bpm) as a ligand for designing molecular complexes as well as polymeric lanthanide materials. A special emphasis is put on the ability of this polydentate neutral ligand to yield compounds of various dimensionalities, to act as a connector between these large ions, and influence their emissive and magnetic properties. This ligand can adopt a terminal or a bridging coordination mode with lanthanide ions, thus generating a wealth of frameworks of various topologies with the 4f elements. The main focus of this review is to show the originality brought by bpm in lanthanide structural chemistry and solid-state photophysics and magnetism.

Europium(II) compounds: simple synthesis of a molecular complex in water and coordination polymers with 2,2'-bipyrimidine-mediated ferromagnetic interactions

Reaction between EuCl(2) and 2,2'-bipyrimidine (bpm) in de-oxygenated water afforded a cationic molecular complex [EuCl(bpm)(2)(H(2)O)(4)][Cl]·H(2)O (1). When performed in an organic solvent such as THF or methanol, the same reaction yielded a 3-dimensional coordination polymer of formula [EuCl(2)(bpm)(MeOH)(0.5)](∞) (2) in which both bpm and the chloride ions act as linkers between the Eu(II) ions. Upon replacing Cl(-) by I(-), two coordination polymers of formula {[Eu(bpm)(2)(H(2)O)(3)][I](2)·0.5bpm}(∞) (3) and {[Eu(I)(bpm)(MeOH)][I]}(∞) (4) were obtained from reaction in water and methanol, respectively. All these compounds were characterized by X-ray crystallography. Investigations of the magnetic properties revealed a weak antiferromagnetic coupling in 2, while 3 and 4 showed a weak ferromagnetic coupling at low temperature.

Syntheses, spectroscopic study and X-ray crystallography of some new phosphoramidates and lanthanide(III) complexes of N-(4-nitrobenzoyl)-N′,N′′-bis(morpholino)phosphoric triamide

New phosphoramidates with the formula RC(O)N(H)P(O)X 2, R = 2-NO2—C6H4, 3-NO2—C6H4 and 4-NO2—C6H4, X = N(CH2CH3) (1)–(3), NC4H8 (4)–(6), and NC4H8O (7)–(9) were synthesized and characterized by 1H, 13C, 31P NMR and IR spectroscopy, and elemental analysis. The reaction of (9) with hydrated lanthanide(III) nitrate leads to ten- or nine-coordinated complexes, (10)–(13). The crystal structure has been determined for (3), (5), (9), (10) and (13). In contrast to all of the previously reported similar phosphoramidate compounds, the —C(O)—N(H)—P(O) skeleton in the free ligand (9) shows a cisoid conformation, with the C=O and P=O double bonds adopting a nearly syn conformation. Quantum chemical calculations were applied for clarifying this exceptional conformational behavior. The monodentate neutral ligand (9) is coordinated to the metal ions via the phosphoryl O atom, adopting the usual anti conformation between the C=O and P=O groups.

N-[Bis(benzylamino)phosphoryl]-2,2,2-trichloroacetamide

In the title compound, C₁₆H₁₇Cl₃N₃O₂P, the P atom has a slightly distorted tetra­hedral configuration. The conformations of the carbonyl and phosphoryl groups are anti to each other. In the crystal, inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into infinite chains parallel to the b axis.

Tris{N-[bis-(dimethyl-amino)phosphino-yl]-2,2,2-trichloro-acetamido}(triphenyl-phosphine oxide)holmium(III)

In the title compound, [Ho(C(6)H(12)Cl(3)N(3)O(2)P)(3)(C(18)H(15)OP)], the Ho(III) ion is surrounded by six O atoms from the three bidentate N-[bis-(dimethyl-amino)phosphino-yl]-2,2,2-trichloro-acetamido ligands (L(-)) and by one O atom from the triphenyl-phosphine oxide ligand, with the formation of a distorted monocapped octa-hedron. In one ligand L(-), the trichloro-methyl group is rotationally disordered between two orientations in a 1:1 ratio, while two dimethyl-amino groups in another ligand L(-) are disordered between two conformations, each with the same 1:1 ratio.

N-[Bis(dimethyl-amino)phosphinoyl]-2,2,2-trichloro-acetamide

In the title compound, C(6)H(13)Cl(3)N(3)O(2)P or CCl(3)C(O)NHP(O)(N(CH(3))(2)), the phosphinoyl group is synclinal to the carbonyl group and acts as an acceptor for an inter-molecular N-H⋯O hydrogen bond from the amide group as the donor.

Tris{N-[bis(pyrrolidin-1-yl)phosphoryl]-2,2,2-trichloroacetamide}trichloridoerbium(III)

The asymmetric unit of the title compound, [ErCl₃(C₁₀H₁₇Cl₃N₃O₂P)₃], contains two independent mol­ecules. In each mol­ecule, the Er^III ion is six-coordinated in a slightly distorted octa­hedral ErO₃Cl₃ geometry with a fac-arrangement of the donor atoms. Intra­molecular N—H⋯Cl hydrogen bonds influence the mol­ecular conformations. Some of the pyrrolidine fragments in the N-[bis(pyrrolidin-1-yl)phosphoryl]-2,2,2-trichloroacetamide ligands are disordered over two conformations of equal occupancy. The unusually porous crystal packing exhibits voids of 162, 158 and 13 ų and short inter­molecular Cl⋯O contacts of 2.876 (3) and 3.022 (4) Å.

Bis{N-[bis-(pyrrolidin-1-yl)phosphor-yl]-2,2,2-trichloro-acetamide}di-nitrato-dioxidouranium(VI)

The crystal structure of the title compound, [U(NO(3))(2)O(2)(C(10)H(17)Cl(3)N(3)O(2)P)(2)], is composed of centrosymmetric [UO(2)(L)(2)(NO(3))(2)] mol-ecules {L is N-[bis-(pyrrolidin-1-yl)phosphor-yl]-2,2,2-trichloro-acetamide, C(10)H(17)Cl(3)N(3)O(2)P}. The U(VI) ion, located on an inversion center, is eight-coordinated with axial oxido ligands and six equatorial oxygen atoms of the phosphoryl and nitrate groups in a slightly distorted hexa-gonal-bipyramidal geometry. One of the pyrrolidine fragments in the ligand is disordered over two conformation (occupancy ratio 0.58:0.42). Intra-molecular N-H⋯O hydrogen bonds between the amine and nitrate groups are found.