Spirocyclic Boraamidinate Complexes of Lanthanide(III) Metals

The reaction of Li₂[Phbam^Dipp] (Phbam^Dipp = PhB(NDipp)₂; Dipp = 2,6‐iPr₂C₆H₃) with lanthanum(III) triiodides LnI₃(THF)_3.5 (Ln = La, Sm) in THF produces complexes of the type [Li(THF)₄]₂[(Phbam^Dipp)₂LnI], which were characterized in solution by multinuclear NMR spectroscopy and in the solid state by single‐crystal X‐ray structural determinations. The ion‐separated complexes are comprised of a spirocyclic anion in which two Phbam^Dipp ligands and an iodide ion are linked to the five‐coordinate metal atom; charge balance is provided by two tetrasolvated lithium ions [Li(THF)₄]⁺.     

Cyclopentadienyl Ruthenium(II) Complexes with Bridging Alkynylphosphine Ligands: Synthesis and Electrochemical Studies

The reaction of [CpRuCl(PPh₃)₂] (Cp=cyclopentadienyl) and [CpRuCl(dppe)] (dppe=Ph₂PCH₂CH₂PPh₂) with bis‐ and tris‐phosphine ligands 1,4‐(Ph₂PC≡C)₂C₆H₄ ( 1 ) and 1,3,5‐(Ph₂PC≡C)₃C₆H₃ ( 2 ), prepared by Ni‐catalysed cross‐coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal‐directed self‐assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh₃)}₂(μ‐dppab)] ( 3 ) and [{CpRu(dppe)}₂(μ‐dppab)](PF₆)₂ ( 4 ), and the mononuclear complex [CpRuCl(PPh₃)(η¹‐dppab)] ( 6 ), which contains a “dangling arm” ligand, were prepared (dppab=1,4‐bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5‐tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh₃)}₃(μ₃‐tppab)] ( 5 ) species was synthesised, which is the first example of a chiral‐at‐ruthenium complex containing three different stereogenic centres. Besides these open‐chain complexes, the neutral cyclic species [{CpRuCl(μ‐dppab)}₂] ( 7 ) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2 . Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh₃)] were obtained, that is, the dinuclear complex [{CpRu(PPh₃)(μ‐dppab)}₂](PF₆)₂ ( 8 ) and the tetranuclear square [{CpRu(PPh₃)(μ‐dppab)}₄](PF₆)₄ ( 9 ). The solid‐state structures of 7 and 8 have been determined by X‐ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X‐band ESR spectroscopy in the case of the electrogenerated paramagnetic species.     

Ruthenium(V) Oxides from Low‐Temperature Hydrothermal Synthesis

Low‐temperature (200 °C) hydrothermal synthesis of the ruthenium oxides Ca_1.5Ru₂O₇, SrRu₂O₆, and Ba₂Ru₃O₉(OH) is reported. Ca_1.5Ru₂O₇ is a defective pyrochlore containing Ru^V/VI; SrRu₂O₆ is a layered Ru^V oxide with a PbSb₂O₆ structure, whilst Ba₂Ru₃O₉(OH) has a previously unreported structure type with orthorhombic symmetry solved from synchrotron X‐ray and neutron powder diffraction. SrRu₂O₆ exhibits unusually high‐temperature magnetic order, with antiferromagnetism persisting to at least 500 K, and refinement using room temperature neutron powder diffraction data provides the magnetic structure. All three ruthenates are metastable and readily collapse to mixtures of other oxides upon heating in air at temperatures around 300–500 °C, suggesting they would be difficult, if not impossible, to isolate under conventional high‐temperature solid‐state synthesis conditions.     

Structural Diversity and Magnetic Properties of Hybrid Ruthenium Halide Perovskites and Related Compounds

There has been a great deal of recent interest in extended compounds containing Ru³⁺ and Ru⁴⁺ in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA₂RuX₆ (X=Cl or Br), MA₂MRuX₆ (M=Na, K or Ag; X=Cl or Br) and MA₃Ru₂X₉ (X=Br) based upon the use of methylammonium (MA=CH₃NH₃⁺) on the perovskite A site. The compounds MA₂RuX₆ with Ru⁴⁺ crystallize in the trigonal space group and can be described as vacancy‐ordered double‐perovskites. The ordered compounds MA₂MRuX₆ with M⁺ and Ru³⁺ crystallize in a structure related to BaNiO₃ with alternating MX₆ and RuX₆ face‐shared octahedra forming linear chains in the trigonal space group. The compound MA₃Ru₂Br₉ crystallizes in the orthorhombic Cmcm space group and displays pairs of face‐sharing octahedra forming isolated Ru₂Br₉ moieties with very short Ru–Ru contacts of 2.789 Å. The structural details, including the role of hydrogen bonding and dimensionality, as well as the optical and magnetic properties of these compounds are described. The magnetic behavior of all three classes of compounds is influenced by spin–orbit coupling and their temperature‐dependent behavior has been compared with the predictions of the appropriate Kotani models.     

Biotransformations of Anticancer Ruthenium(III) Complexes: An X‐Ray Absorption Spectroscopic Study

An anti‐metastatic drug, NAMI‐A ((ImH)[Ru^IIICl₄(Im)(dmso)]; Im=imidazole, dmso=S‐bound dimethylsulfoxide), and a cytotoxic drug, KP1019 ((IndH)[Ru^IIICl₄(Ind)₂]; Ind=indazole), are two Ru‐based anticancer drugs in human clinical trials. Their reactivities under biologically relevant conditions, including aqueous buffers, protein solutions or gels (e.g, albumin, transferrin and collagen), undiluted blood serum, cell‐culture medium and human liver (HepG2) cancer cells, were studied by Ru K‐edge X‐ray absorption spectroscopy (XAS). These XAS data were fitted from linear combinations of spectra of well‐characterised Ru compounds. The absence of XAS data from the parent drugs in these fits points to profound changes in the coordination environments of Ru^III. The fits point to the presence of Ru^IV/III clusters and binding of Ru^III to S‐donor groups, amine/imine and carboxylato groups of proteins. Cellular uptake of KP1019 is approximately 20‐fold higher than that of NAMI‐A under the same conditions, but it diminishes drastically after the decomposition of KP1019 in cell‐culture media, which indicate that the parent complex is taken in by cells through passive diffusion.     

One‐dimensional Salen‐type Chain‐like Lanthanide(III) Coordination Polymers: Syntheses,Crystal Structures,and Fluorescence Properties

Four salen‐type lanthanide(III) coordination polymers [LnH₂L(NO₃)₃(MeOH)_x]_n [Ln = La ( 1 ), Ce ( 2 ), Sm ( 3 ), Gd ( 4 )] were prepared by reaction of Ln(NO₃)₃ · 6H₂O with H₂L [H₂L = N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine]. Single‐crystal X‐ray diffraction analysis revealed that H₂L effectively functions as a bridging ligand forming a series of 1D chain‐like polymers. The solid‐state fluorescence spectra of polymers 1 and 2 emit single ligand‐centered green fluorescence, whereas 3 exhibits typical red fluorescence of Sm^III ions. The lowest triplet level of ligand H₂L was calculated on the basis of the phosphorescence spectrum of Gd^III complex 4 . The energy transfer mechanisms in the lanthanide polymers were described and discussed.     

Ruthenium complexes of substituted hydrazine: new solution- and solid-state binding modes

The methylhydrazine complex [Ru(NH(2)NHMe)(PyP)(2)]Cl(BPh(4)) (PyP=1-[2-(diphenylphosphino)ethyl]pyrazole) was synthesised by addition of methylhydrazine to the bimetallic complex [Ru(mu-Cl)(PyP)(2)](2)(BPh(4))(2). The methylhydrazine ligand of the ruthenium complex has two different binding modes: side-on (eta(2)-) when the complex is in the solid state and end-on (eta(1)-) when the complex is in solution. The solid-state structure of [Ru(PyP)(2)(NH(2)NHMe)]Cl(BPh(4)) was determined by X-ray crystallography. 2D NMR spectroscopic experiments with (15)N at natural abundance confirmed that in solution the methylhydrazine is bound to the metal centre by only the -NH(2) group and the ruthenium complex retains an octahedral conformation. Hydrazine complexes [RuCl(PyP)(2)(eta(1)-NH(2)NRR')]OSO(2)CF(3) (in which R=H, R'=Ph, R=R'=Me and NRR'=NC(5)H(10)) were formed in situ by the addition of phenylhydrazine, 1,1-dimethylhydrazine and N-aminopiperidine, respectively, to a solution of the bimetallic complex [Ru(mu-Cl)(PyP)(2)](2)(OSO(2)CF(3))(2) in dichloromethane. These substituted hydrazine complexes of ruthenium were shown to exist in an equilibrium mixture with the bimetallic starting material.     

Regioselective Synthesis and Characterization of Multinuclear Convex‐Bound Ruthenium‐[n]Cycloparaphenylene (n=5 and 6) Complexes

Mono‐ and multinuclear complexes of ruthenium and [n]cycloparaphenylene (CPP, n=5 and 6) were synthesized in excellent yields through ligand exchange of the cationic complex [(Cp)Ru(CH₃CN)₃](PF₆) with CPP. In the multinuclear complexes, ruthenium selectively coordinated to alternate paraphenylene units to give bis‐ and tris‐coordinated Ru complexes for [5] and [6]CPPs, respectively. Single‐crystal X‐ray analysis revealed the Ru was coordinated with η⁶‐hapticity on the convex surface of CPP.     

Synthesis,Characterization, and Structural Comparisons of the First Neodymium(III) Sulfite‐Acetate Crystal Structure

The first lanthanide sulfite compound with a secondary ligand, Nd(SO₃)(C₂H₃O₂), was hydrothermally synthesized and solved with single‐crystal X‐ray diffraction. In order to prevent the facile oxidation of the sulfite to sulfate, careful control of both pH and reaction temperature were required for successful synthesis of the title compound; even slight changes in conditions allow for the facile oxidation of sulfite to sulfate and yields the known [Nd(C₂H₃O₂)(SO₄)(H₂O)₂] structure. This two‐dimensional sheet topology further expands the chemistry of lanthanide sulfite extended structures and also allows for easy structural comparisons to other lanthanide sulfite compounds and the above mentioned neodymium sulfate‐acetate compound.     

Self‐Assembly of Organic Chromosphere Cations with Inorganic Lanthanide(III) Complex Counterions

Hybrid complexes based on a D‐π‐A type dye p‐aminostyryl‐pyridinum cation and a lanthanide(III) complex anion were synthesized by ionic exchange reaction. Different alkyl‐substituted amino groups were used as electron donors in organic dye cations. The synthesized complexes were characterized by elemental analysis. In addition, the structural features of them were studied by single‐crystal X‐ray diffraction analysis. Their optical properties were systematically investigated by absorption and fluorescence spectroscopy.     

Gold(I) and gold(III) corroles

Corrole complexes with gold(I) and gold(III) were synthesized and their structural, photophysical, and electrochemical properties investigated. This work includes the X-ray crystallography characterization of gold(I) and gold(III) complexes, both chelated by a corrole with fully brominated β-pyrrole carbon atoms. The mononuclear and chiral gold(I) corrole appears to be the first of its kind within the porphyrinoid family, while the most unique property of the gold(III) corrole is that it displays phosphorescence at ambient temperatures.     

Nickel(II)–Lanthanide(III) Magnetic Exchange Coupling Influencing Single‐Molecule Magnetic Features in {Ni2Ln2} Complexes

Four isostructural [Ni₂Ln₂(CH₃CO₂)₃(HL)₄(H₂O)₂]³⁺(Ln³⁺=Dy ( 1 ), Tb ( 2 ), Ho ( 3 ) or Lu ( 4 )) complexes and a dinuclear [NiGd(HL)₂(NO₃)₃] ( 5 ) complex are reported (where HL=2‐methoxy‐6‐[(E)‐2′‐hydroxymethyl‐phenyliminomethyl]‐phenolate). For compounds 1 – 3 and 5 , the Ni²⁺ ions are ferromagnetically coupled to the respective lanthanide ions. The ferromagnetic coupling in 1 suppresses the quantum tunnelling of magnetisation (QTM), resulting in a rare zero dc field Ni–Dy single‐molecule magnet, with an anisotropy barrier U_eff of 19 K.     

Structural Investigation of Homoleptic Lanthanide(III) Tris(pivalamidinates), [tBuC(NiPr)2]3Ln (Ln = Ce,Eu, Tb)

Three new homoleptic lanthanide(III) tris(pivalamidinates), [tBuC(NiPr)₂]₃Ln (Ln = Ce ( 1 ), Eu ( 2 ), Tb ( 3 )) were synthesized by reaction of anhydrous LnCl₃ with 3 equivalents of in situ prepared Li[tBuC(NiPr)₂] in THF. X‐ray structural analyses confirmed the presence of homoleptic, unsolvated tris(amidinates) in which the central Ln³⁺ ions are coordinated by three chelating pivalamidinate anions in a distorted all‐nitrogen trigonal prismatic arrangement. Compounds 1 – 3 all crystallize in the monoclinic system, with 1 and 3 containing solvent of crystallization ( 1 : toluene, 3 : n‐pentane) whereas the europium derivative 2 is unsolvated.     

Unusual Structural Features in the Lysozyme Derivative of the Tetrakis(acetato)chloridodiruthenium(II,III) Complex

The reaction between the paddle‐wheel tetrakis(acetato)chloridodiruthenium(II,III) complex, [Ru₂(μ‐O₂CCH₃)₄Cl] and hen egg‐white lysozyme (HEWL) was investigated through ESI‐MS and UV/Vis spectroscopy and the formation of a stable metal–protein adduct was unambiguously demonstrated. Remarkably, the diruthenium core is conserved in the adduct while two of the four acetate ligands are released. The crystal structure of this diruthenium–protein derivative was subsequently solved through X‐ray diffraction analysis to 2.1 Å resolution. The structural data are in agreement with the solution results. It was found that HEWL binds two diruthenium moieties, at Asp101 and Asp119, respectively, with the concomitant release of two acetate ligands from each diruthenium center.