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Hydrolysis of polysorbate in biopharmaceutical products has been ascribed to the enzymatic activity from trace levels of residual host cell proteins. In recent years, significant efforts to identify the causative enzymes typically used elaborate, material-intensive and time-consuming approaches. Therefore, the lack of fast and sensitive assays to monitor their activity remains a major bottleneck for supporting process optimization and troubleshooting activities where time and sample throughput are crucial constraints. To address this bottleneck, we developed a novel Electrochemiluminescence-based Polysorbase Activity (EPA) assay to measure hydrolytic activities in biotherapeutics throughout the drug substance manufacturing process. By combining the favorable features of an in-house designed surrogate substrate with a well-established detection platform, the method yields fast (∼36 h turnaround time) and highly sensitive readouts compatible with high-throughput testing. The assay capability for detecting substrate conversion in a precise and reliable manner was demonstrated by extensive qualification studies and by employing a number of recombinant hydrolases associated with polysorbate hydrolysis. In addition, high assay sensitivity and wide applicability were confirmed for in-process pool samples of three different antibody products by performing a head-to-head comparison between this method and an established liquid chromatography - mass spectrometry based assay for the quantification of free fatty acids. Overall, our results suggest that this new approach is well-suited to resolve differences in hydrolytic activity through all stages of purification., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

In this contribution, the first amidinate and amidine derivatives of p -carborane are described. Double lithiation of p -carborane ( 1 ) with n -butyllithium followed by treatment with 1,3-diorganocarbodiimides, R-N=C=N-R (R = i Pr, Cy (= cyclohexyl)), in DME or THF afforded the new p -carboranylamidinate salts p -C 2 H 10 B 10 [C(N i Pr) 2 Li(DME)] 2 ( 2 ) and p -C 2 H 10 B 10 [C(NCy) 2 Li(THF) 2 ] 2 ( 3 ). Subsequent treatment of 2 and 3 with 2 equiv. of chlorotrimethylsilane (Me 3 SiCl) provided the silylated neutral bis(amidine) derivatives p -C 2 H 10 B 10 [C{ i PrN(SiMe 3 )}(=N i Pr)] 2 ( 4 ) and p -C 2 H 10 B 10 [C{CyN(SiMe 3 )}(=NCy)] 2 ( 5 ). The new compounds 3 and 4 have been structurally characterized by single-crystal X-ray diffraction. The lithium carboranylamidinate 3 comprises a rare trigonal planar coordination geometry around the lithium ions.

A series of brightly colored alkaline earth metal 1,3-dimethylviolurates M(Me 2 Vio) 2 have been prepared and fully characterized. The title compounds AE(Me 2 Vio) 2 · n H 2 O (AE = Mg, n = 6 (3); AE = Ca, n = 8 (4), AE = Sr, n = 6 (5); AE = Ba, n = 4 (6)) were obtained by neutralizing 1,3-dimethylvioluric acid monohydrate (=H(Me 2 Vio)·H 2 O; 2) with 0.5 equiv. of the corresponding metal dihydroxides AE(OH) 2 . The hair-like appearance of the Sr derivative 5 prevented the growth of single-crystals. This problem could be solved by crystallizing the crown ether derivative Sr(Me 2 Vio) 2 (18-crown-6) (5a). The isolated salts exhibit intense colors ranging from red to purple. Various attempts to prepare the beryllium derivative Be(Me 2 Vio) 2 failed. Instead, work-up of the reaction mixtures provided pink crystals of a new modification of 2 formulated as [H 3 O][Me 2 Vio] (2b) as shown by an X-ray diffraction study. An unexpected oxidation reaction of the barium salt Ba(Me 2 Vio) 2 led to formation of the novel mixed-anion salt Ba(Me 2 Vio)(Me 2 NO 2 Barb)·2H 2 O (8, Me 2 NO 2 Barb - = 1,3-dimethyl-5-nitrobarbiturate anion). Compound 8 could also be synthesized deliberately by treatment of Ba(OH) 2 with a 1 : 1 mixture of 2 and 1,3-dimethyl-5-nitrobarbituric acid (7, =H(Me 2 NO 2 Barb)·H 2 O). All new compounds were fully characterized by their IR, Raman, NMR ( 1 H, 13 C{ 1 H}) and UV-vis spectra as well as elemental analyses. Single-crystal X-ray diffraction studies revealed that the solid-state structures of compounds 3, 4, 5a and 6 are governed by the typical coordination behavior of the alkaline-earth metals, i.e. increasing coordination numbers and a decreasing degree of hydration when going from Mg to Ba. The dimensions of the structures range from hydrogen-bonded ions (3) over monomeric, neutral complex molecules (4, 5a), to polymeric networks (6). The successful isolation of the mixed-anion barium salt 8 adds a new facet to the coordination chemistry of violurate and related ligands.

The synthesis and structural characterization of Ae(Tp iPr2 ) 2 (Ae = Mg, Ca, Sr, Ba; Tp iPr2 = hydrido-tris(3,5-diisopropyl-pyrazol-1-yl)borate) are reported. In the crystalline state, the alkaline earth metal centers are six-coordinate, even the small Mg 2+ ion, with two κ 3 - N , N ', N ''-Tp i Pr2 ligands, disposed in a bent arrangement (B···Ae···B < 180°). However, contrary to the analogous Ln(Tp iPr2 ) 2 (Ln = Sm, Eu, Tm, Yb) compounds, which all exhibit a bent-metallocene structure close to C s symmetry, the Ae(Tp iPr2 ) 2 compounds exhibit a greater structural variation. The smallest Mg(Tp iPr2 ) 2 has crystallographically imposed C 2 symmetry, requiring both bending and twisting of the two Tp i Pr2 ligands, while with the similarly sized Ca 2+ and Sr 2+ , the structures are back toward the bent-metallocene C s symmetry. Despite the structural variations, the B···M···B bending angle follows a linear size-dependence for all divalent metal ions going from Mg 2+ to Sm 2+ , decreasing with increasing metal ion size. The complex of the largest metal ion, Ba 2+ , forms an almost linear structure, B···Ba···B 167.5°. However, the "linearity" is not due to the compound approaching the linear metallocene-like geometry, but is the result of the pyrazolyl groups significantly tipping toward the metal center, approaching "side-on" coordination. An attempt to rationalize the observed structural variations is made.

The first rubidium and cesium enediamide complexes based on bulky 1,4-diaza-1,3-diene ligands (DADs) have been prepared by metalation of either 1,4-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene ( 1 , = H2 DAD Dipp ) or 1,4-bis(2,6-diisopropylphenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene ( 2 , = Me2 DAD Dipp ) with an excess of Rb or Cs metals in coordinating solvents such as tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME). All new complexes were fully characterized by spectroscopic and analytical methods as well as single-crystal X-ray diffraction studies., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

The reaction of potassium carbonate with elemental sulfur or selenium in acetone in the presence of [PPN]Cl (PPN = (Ph 3 P) 2 N) produces catena-[S 12 ] 2- , the longest structurally characterised polysulfide dianion, or spiro-[Se 11 ] 2- as ion-separated [PPN] + salts.

Treatment of scandium nitrate tetra-hydrate with the tetra-dentate ligand H 2 salophen [ N , N '-bis-(salicyl-idene)-1,2-phenyl-enedi-amine] afforded the yellow dinuclear complex Sc(NO 3 ) 2 (μ-salophen)Sc(salophen)(EtOH) or [Sc 2 (C 20 H 14 N 2 O 2 ) 2 (NO 3 ) 2 (C 2 H 6 O)] (systematic name: (ethanol-κ O )bis-(nitrato-κ 2 O , O '){μ-2,2'-[1,2-phenyl-enebis(nitrilo-methanylyl-idene)]diphenolato-κ 4 N , N ', O , O ':κ 2 O , O '}{2,2'-[1,2-phenyl-enebis(nitrilo-methanylyl-idene)]diphenolato-κ 4 O , N , N ', O '}discandium). In this compound, one salophen ligand displays a bridging coordination via the two oxygen atoms, while the other salophen ligand is attached to only one Sc center. This arrangement is stabilized by a hydrogen-bonded EtOH co-ligand, and by π-π stacking inter-actions between the two salophen ligands.

The first potassium amidino-guanidinate complex, catena -poly[[bis-(μ-1-amidinato- N , N ', N '', N '''-tetra-iso-propyl-guanidinato-κ 5 N 1 : N 1 , N 2 : N 2 , N 4 )dipotassium]-μ-1,2-di-meth-oxy-ethane-κ 2 O : O '], [K 2 (C 14 H 32 N 4 ) 2 (C 4 H 10 O 2 )] n or [{ i PrN= CHN( i Pr)N(N i Pr) 2 K} 2 ( μ -DME)] n where DME is 1,2-di-meth-oxy-ethane, has been synthesized and structurally characterized. The title compound was isolated in 76% yield from a reaction of N , N '-diiso-propyl-carbodi-imide with potassium hydride in DME. The single-crystal X-ray structure determination of the title compound revealed a polymeric chain structure comprising cage-like dimeric units, with the amidino-guanidinate ligand displaying a mixed σ-/π-coordination mode.

Deliberate hydrolysis of lithium cyclo-propyl-alkynylamidinates, Li[ c -C 3 H 5 -C≡C(N R ') 2 ] [ R ' = i Pr, Cy = cyclo-hex-yl)], afforded the hitherto unknown neutral cyclo-propyl-alkynyl-amidine derivatives c -C 3 H 5 -C≡C-C(N R ')(NH R ') [ R ' = i Pr ( 1 ), Cy ( 2 )]. Subsequent reactions of 1 or 2 with metal(II) chlorides, M Cl 2 ( M = Mn, Fe, Co), provided the title complexes di-chlorido-bis-(3-cyclo-propyl- N , N '-diisopropyl-prop-2-ynamidine)-manganese(II), [MnCl 2 (C 12 H 20 N 2 ) 2 ], ( 3 ), di-chlorido-bis-(3-cyclo-propyl- N , N '-diisopropyl-prop-2-ynamidine)-iron(II), [FeCl 2 (C 12 H 20 N 2 ) 2 ], ( 4 ), di-chlorido-bis-( N , N '-di-cyclo-hexyl-3-cyclo-propyl-prop-2-ynamidine)-iron(II), [FeCl 2 (C 18 H 28 N 2 ) 2 ], ( 5 ), and di-chlorido-bis-( N , N '-di-cyclo-hexyl-3-cyclo-propyl-prop-2-ynamidine)-cobalt(II), [CoCl 2 (C 18 H 28 N 2 ) 2 ], ( 6 ), or more generally M Cl 2 [ c -C 3 H 5 -C≡C-C(N R ')(NH R ')] 2 [ R ' = i Pr, M = Mn ( 3 ), Fe ( 4 ); R ' = Cy, M = Fe ( 5 ), Co ( 6 )] in moderate yields (30-39%). Besides their spectroscopic data (IR and MS) and elemental analyses, all complexes 3 - 6 were structurally characterized. The two isopropyl-substituted complexes 3 and 4 are isotypic, and so are the cyclo-hexyl-substituted complexes 5 and 6 . In all cases, the central metal atom is coordinated by two Cl atoms and two N atoms in a distorted-tetra-hedral fashion, and the structure is supported by intra-molecular N-H⋯Cl hydrogen bonds.

The migration of Me3Si groups ("Wanderlust") in rare-earth triple-decker sandwich complexes of the type Ln2(COT'')3 (COT'' = bis(trimethylsilyl)cyclooctatetraenyl) has been elucidated by a combined experimental and computational study. For the first time, two isomers of a Ln2(COT'')3 triple-decker have been isolated and characterized in the case of Y2(COT'')3.

The electronic and molecular structures of the lithium and sodium complexes of 1,4-bis(2,6-diisopropylphenyl)-2,3-dimethyl-1,4-diazabutadiene ( Me2 DAD Dipp ) were fully characterized by using a multi-frequency electron paramagnetic resonance (EPR) spectroscopy approach and crystallography, together with density functional theory (DFT) calculations. EPR measurements, using T 1 relaxation-time-filtered pulse EPR spectroscopy, revealed the diagonal elements of the A and g tensors for the metal and ligand sites. It was found that the central metals in the lithium complexes had sizable contributions to the SOMO, whereas this contribution was less strongly observed for the sodium complex. Such strong contributions were attributed to structural specifications (e.g. geometrical data and atomic size) rather than electronic effects.

Three new types of transition metal carboranylamidinate complexes are reported. The tetranuclear Mn(ii) complex Mn4Cl6[(o-C2B10H10)C(NiPr)(NHiPr)]2(THF)4·THF (2) was prepared by treatment of anhydrous MnCl2 with Li[(o-C2B10H10)C(NiPr)(NHiPr)] ([double bond, length as m-dash]Li[HLiPr]) in THF, while the analogous reaction with FeCl2 afforded ionic [Li(DME)3][FeCl2{(o-C2B10H10)C(NiPr)(NHiPr)}] (3). The dinuclear Mo(ii) complex Mo2[(o-C2B10H10)C(NiPr)(NHiPr)]2(OAc)2·2THF (4), obtained from Mo2(OAc)4 and 2 equiv. of Li[HLiPr], represents the first example of a M-M multiple bond stabilized by carboranylamidinate ligands. All title compounds were structurally characterized by single-crystal X-ray diffraction. The M-M bonding in compound 4 has been further elucidated through Complete Active Space Self Consistent Field (CASSCF) calculations.

The synthesis and photoluminescence properties of the bright-yellow organocerium complex [{(CptBu2 ) 2 Ce(μ-Cl)} 2 ] (CptBu2 =1,3-di(tert-butyl)cyclopentadienyl) are presented. This coordination compound exhibits highly efficient photoluminescence within the yellow-light wavelength range, with a high internal quantum yield of 61(±2) % at room temperature. The large red shift is attributed to the delocalizing ability of the aromatic ligands, whilst its quantum yield even makes this compound competitive with Ce 3+ -activated LED phosphors in terms of its photoluminescence efficiency (disregarding its thermal stability). A bridging connection between two crystallographically independent Ce 3+ ions is anticipated to be the reason for the highly efficient photoluminescence, even up to room temperature. The emission spectrum is characterized by two bands in the orange-light range at both 10 K and room temperature, which are attributed to the parity-allowed transitions 5d 1 ( 2 D 3/2 )→4f 1 ( 2 F 7/2 ) and 5d 1 ( 2 D 3/2 )→4f 1 ( 2 F 5/2 ) of Ce 3+ , respectively. The photoluminescence spectra were interpreted in relation to the structure and vibrational modes of the coordination compound. The spectra and optical properties indicate that trivalent cerium ions are the dominant species in the ground state, which also resolves an often-encountered ambiguity in organocerium compounds. This result shows that photoluminescence spectroscopy is a versatile tool that can help elucidate the oxidation state of Ce in such compounds., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A unique trivalent manganese siloxide complex, blue-violet Mn III Li 2 Cl[(Ph 2 SiO) 2 O] 2 (THF) 4 ·2THF (3) has been prepared by a straightforward two-step synthetic protocol. Lithiation of (Ph 2 SiOH) 2 O (1) followed by reaction with MnCl 2 (THF) 2 gave the structurally remarkable Mn(ii) precursor Mn II Li 4 Cl 2 [(Ph 2 SiO) 2 O] 2 (THF) 5 ·2THF (2). Surprisingly, the final oxidation step could be achieved using KMnO 4 in THF to provide the Mn(iii) species 3 in high yield (91%). Both title compounds were structurally characterized by single-crystal X-ray diffraction.

The reaction of EuI 2 (THF) 2 with potassium hydro-tris-(3,5-diiso-propyl-pyrazol-yl)borate (K[HB(3,5- i Pr2 pz) 3 ] (= KTp i Pr2 , pz = pyrazol-yl) in a molar ratio of 1:1.5 resulted in extensive ligand fragmentation and formation of the europium(II) mono(scorpionate) complex bis-(3,5-diisopropyl-1 H -pyrazole)[hydro-tris-(3,5-diiso-propyl-pyrazol-yl)borato]iodido-europium(II), [Eu(C 27 H 46 BN 6 )I(C 9 H 16 N 2 ) 2 ] or (Tp i Pr2 )(3,5- i Pr2 pzH) 2 Eu II I, 1 , in high yield (78%). As a typical by-product, small amounts of the sterically crowded pyraza-bole derivative trans -4,8-bis-(3,5-diiso-propyl-pyrazol-1-yl)-1,3,5,7-tetra-iso-propyl-pyraza-bole, C 36 H 62 B 2 H 8 or trans -{(3,5- i Pr2 pz)HB(μ-3,5- i Pr2 pz)} 2 , 2 , were formed. Both title compounds have been structurally characterized through single-crystal X-ray diffraction. In 1 , two isopropyl groups are each disordered over two orientations with occupancy ratios of 0.574 (10):0.426 (10) and 0.719 (16):0.281 (16). In 2 , one isopropyl group is similarly disordered, occupancy ratio 0.649 (9):0.351 (9).

This Tutorial Review provides an overview of the historic and current development of the organometallic chemistry of cerium in its oxidation state 4+. Among the tetravalent lanthanide ions, only Ce 4+ forms stable coordination compounds (e.g. (NH 4 ) 2 [Ce(NO 3 ) 6 ]). Important fields of applications for cerium(iv) compounds include organic synthesis, bioinorganic chemistry, materials science, and industrial catalysis. In sharp contrast, organometallic cerium(iv) compounds are still exceedingly rare. The history of organocerium(iv) compounds is an exciting story of ups and downs. The so-called cerocene (= bis(η 8 -cyclooctatetraenyl) cerium) has been known since 1976. Other early reports e.g. about Cp 4 Ce (Cp = η 5 -cyclopentadienyl), were later disproven. However, significant progress in this field has been made in recent years through the use of carefully designed ligands and more sophisticated synthesis protocols. Taking the case of organocerium(iv) chemistry, this Tutorial Review also tries to exemplarily show how difficult synthetic and theoretical problems can eventually be solved through newly designed synthesis strategies (e.g. as accomplished for cyclopentadienyl and carbene derivatives) and a rewarding collaboration between synthetic and theoretical chemists (cf. the cerocene problem).

Reaction of 2 equiv. of the lithium carboranylamidinate Li[ o -(C 2 H 10 B 10 )C(NCy)(NHCy)] with SnCl 2 in THF afforded the stannylene compound bis( N , N '-dicyclohexylamidinatocarboranate)tin(II), Sn II [ o -(C 2 H 10 B 10 )C(NCy)(NHCy)] 2 ( 1 ). A similar reaction of SnCl 4 with 2 equiv. of Li[ o -(C 2 H 10 B 10 )C(N i Pr)(NH i Pr)] unexpectedly afforded the known solvated penta-chlorido-stannate(IV) salt [Li(THF) 4 ][SnCl 5 (THF)] as the main reaction product. Small amounts of the new chlorido-tin(IV) bis-(carboranylamidinate) bis( N , N '-diiso-propylamidinatocarboranate)chloridotin(IV), Sn IV Cl[ o -(C 2 H 10 B 10 )C(N i Pr)(NH i Pr)][ o -(C 2 H 10 B 10 )C(N i Pr) 2 ] ( 2 ), were isolated as a by-product. Single-crystal X-ray structure analysis revealed a κC , κN -chelating coordination of the carboranylamidinate ligands in both 1 and 2 . The Sn atom in 1 adopts a pseudo-trigonal-bipyramidal coordination under participation of a stereoactive lone pair. In 2 , a trigonal-bipyramidal coordination of Sn is completed by a chlorido ligand.

A series of heteroleptic tris(cyclopentadienyl) Ce IV complexes has been isolated and crystallographically characterized, revealing the broad accessibility of such organocerium(IV) compounds. The oxidation of complexes Cp Me 3 Ce(thf) and Cp' 3 Ce(thf) (Cp Me =C 5 H 4 Me, Cp'=C 5 H 4 SiMe 3 ), bearing monosubstituted electron-poor cyclopentadienyl ligands, with 0.5 equivalents of 1,4-benzoquinone or C 2 Cl 6 gave the cerium(IV) hydroquinolate complexes Cp Me 3 Ce(OC 6 H 4 O)CeCp Me 3 and Cp' 3 Ce(OC 6 H 4 O)CeCp' 3 , or the chloride complexes Cp Me 3 CeCl and Cp' 3 CeCl, respectively; the iodide complex Cp' 3 CeI was obtained from the reaction of Cp' 3 Ce(thf) with elemental iodine. The behavior of Cp' 3 CeCl in salt metathesis protocols employing alkali metal amides or alkyl, alkoxide, and aryloxide reagents was investigated, which gave rise to the robust and isolable cerium(IV) alkoxide Cp' 3 Ce(OtBu). Trivalent [Cp' 2 CeCl] 2 was synthesized by AlMe 4 →Cl exchange utilizing Cp' 2 Ce(AlMe 4 ) and AlMe 2 Cl. The reactivity of [Cp' 2 CeCl] 2 towards the oxidants Ph 3 CCl, C 2 Cl 6 , 1,4-benzoquinone, and I 2 has been assessed, and has provided useful information on Ce III /Ce IV redox deactivation pathways. In addition to X-ray structure analysis, all the complexes were characterized by NMR, DRIFT (diffuse reflectance IR Fourier transform), and UV/Vis spectroscopy as well as elemental analysis. The tetravalent compounds were further analyzed for their magnetic susceptibility by using Evans' method., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reactivity of Li[Sc(COT'') 2 ] (1; COT''=1,4-bis(trimethylsilyl)cyclooctatetraenyl) towards CoCl 2 is considerably different from that of related lanthanide triple-decker sandwich complexes. In addition to the expected triple-decker complex Sc 2 (COT'') 3 (2), the complex Sc 2 {μ-BTHP}(COT'') 2 (3) is formed, which comprises the novel BTHP 2- ligand (BTHP 2- =bis(3,5-bis(trimethylsilyl)-1,3a,6,6a-tetrahydropentalene-1-yl)diide or bis(2,7-bis(trimethylsilyl)bicyclo[3.3.0]octa-2,7-dien-4-yl)diide, C 16 H 10 (SiMe 3 ) 4 2- ). The formation of 3 is likely facilitated by the fact that scandium prefers η 8 ,η 3  coordination rather than highly symmetric η 8 ,η 8  coordination, and the η 3 -coordinated COT'' ligand in 1 is activated owing to a loss of aromaticity. Acid hydrolysis of 3 leads to air-stable H 2 BTHP (4)., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The base-catalyzed Michael addition of 2-methyl-acryl-amide to benzotriazole afforded 3-(1 H -benzotriazol-1-yl)-2-methyl-propanamide, C 10 H 12 N 4 O ( 1 ), in 32% yield in addition to small amounts of isomeric 3-(2 H -benzotriazol-2-yl)-2-methyl-propanamide, C 10 H 12 N 4 O ( 2 ). In a similar manner, 3-(1 H -benzotriazol-1-yl)- N , N -di-methyl-propanamide, C 11 H 14 N 4 O ( 3 ), was prepared from benzotriazole and N , N -di-methyl-acryl-amide. All three products have been structurally characterized by single-crystal X-ray diffraction. The crystal structures of 1 and 2 comprise infinite arrays formed by N-H⋯O and N-H⋯N bridges, as well as π-π inter-actions, while the mol-ecules of 3 are aggregated to simple π-dimers in the crystal.

The blood-red plutonocene complex Pu(1,3-COT'')(1,4-COT'') (4; COT''=η 8 -bis(trimethylsilyl)cyclooctatetraenyl) has been synthesized by oxidation of the anionic sandwich complex Li[Pu(1,4-COT'') 2 ] (3) with anhydrous cobalt(II) chloride. The first crystal structure determination of an organoplutonium(IV) complex revealed an asymmetric sandwich structure for 4 where one COT'' ring is 1,3-substituted while the other retains the original 1,4-substitution pattern. The electronic structure of 4 has been elucidated by a computational study, revealing a probable cause for the unexpected silyl group migration., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first antimony(III) aziridinyl derivatives are reported. Treatment of anhydrous SbCl 3 with N-lithioaziridine Li(Azn) (Azn = NC 2 H 4 ) afforded the structurally unique heterobimetallic lithium/antimony(III) amide complex [Li 3 Sb(μ 3 -Cl) 2 (μ-Azn) 4 (THF) 2 ] ∞ (1). Homoleptic Sb 2 (Azn) 6 (2) has become available for the first time through an amide group exchange reaction between Sb(NMe 2 ) 3 and 3 equiv of aziridine. The low-melting Sb 2 (Azn) 6 exhibits a "weak dimer" structure in the crystal.

The first metallasilsesquioxanes comprising potassium and uranium have been synthesized and structurally characterized by single-crystal X-ray diffraction. (Cy 7 Si 7 O 12 ) 2 K 6 (DME) 4 (2; Cy = cyclohexyl) is a centrosymmetric dimer, in which the two silsesquioxide ligands are interconnected by μ 3 - and μ 4 -bridging siloxide moieties. (Cy 7 Si 7 O 12 ) 2 U VI (3) represents the first metallasilsesquioxane complex of an actinide element, featuring a U atom that is coordinated by two tridentate silsesquioxide ligands in a distorted octahedral fashion. The different structural effects of the large metal atomic radii are discussed.

mRNA localization is an essential mechanism of gene regulation and is required for processes such as stem-cell division, embryogenesis and neuronal plasticity. It is not known which features in the cis-acting mRNA localization elements (LEs) are specifically recognized by motor-containing transport complexes. To the best of our knowledge, no high-resolution structure is available for any LE in complex with its cognate protein complex. Using X-ray crystallography and complementary techniques, we carried out a detailed assessment of an LE of the ASH1 mRNA from yeast, its complex with its shuttling RNA-binding protein She2p, and its highly specific, cytoplasmic complex with She3p. Although the RNA alone formed a flexible stem loop, She2p binding induced marked conformational changes. However, only joining by the unstructured She3p resulted in specific RNA recognition. The notable RNA rearrangements and joint action of a globular and an unfolded RNA-binding protein offer unprecedented insights into the step-wise maturation of an mRNA-transport complex.

The silver(I) amidinates bis-[μ- N 1 , N 2 -bis-(propan-2-yl)benzamidinato-κ 2 N 1 : N 2 ]disilver(I), [Ag 2 (C 13 H 19 N 2 ) 2 ] or [Ag{PhC(N i Pr) 2 }] 2 ( 1 ), and bis-(μ- N 1 , N 2 -di-cyclohexyl-3-cyclo-propyl-propynamidinato-κ 2 N 1 : N 2 )disilver(I), [Ag 2 (C 18 H 27 N 2 ) 2 ] or [Ag{ cyclo -C 3 H 5 -C≡C-C(NCy) 2 }] 2 ( 2a ), exist as centrosymmetric dimers with a planar Ag 2 N 4 C 2 ring and a common linear coordination of the metal atoms in the crystalline state. Moiety 2a forms a co-crystal with the related lithium amidinate, namely bis-(μ- N 1 , N 2 -di-cyclo-hexyl-3-cyclo-propyl-propynamidinato-κ 2 N 1 : N 2 )disilver(I) bis-(μ- N 1 , N 2 -di-cyclo-hexyl-3-cyclo-propyl-propynamidinato-κ 3 N 1 , N 2 : N 1 )bis-(tetra-hydro-furan-κ O )lithium(I) toluene monosolvate, [Ag 2 (C 18 H 27 N 2 ) 2 ][Li 2 (C 18 H 27 N 2 ) 2 (C 4 H 8 O) 2 ]·C 7 H 8 or [Ag{ cyclo -C 3 H 5 -C≡ C - C (NCy) 2 }] 2 [Li{ cyclo -C 3 H 5 -C≡C-C(NCy) 2 }(THF)] 2 ·C 7 H 8 , composed as 2a × 2b × toluene. The lithium moiety 2b features a typical ladder-type dimeric structure with a distorted tetra-hedral coordination of the metal atoms. In the silver(I) derivatives 1 and 2a , the amidinate ligand adopts a μ-κ N :κ N ' coordination, while it is a μ-κ N :κ N :κ N '-coordination in the case of lithium derivative 2b .

The crystal and mol-ecular strutures of two solvated forms of [K(18 c 6)]OAc (18 c 6 = 18-crown-6 = 1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane and OAc = acetate) were determined by single-crystal X-ray diffraction, namely (acetato-κ 2 O , O ')(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ 6 O )potassium dihydrate, [K(CH 3 COO)(C 12 H 24 O 6 )]·2H 2 O ( 1 ) and (acetato-κ 2 O , O ')aqua-(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ 6 O )potassium acetic acid monosolvate [K(CH 3 COO)(C 12 H 24 O 6 )(H 2 O)]·CH 3 COOH ( 2 ). In both compounds, the acetate anion is bonded to the potassium ion in a chelating fashion and the metal atom is consequently slightly displaced from the O 6 plane of the crown ether. In the crystals, O-H⋯O hydrogen bonds lead to a polymeric ladder structure in the dihydrate 1 , while the acetic acid hydrate 2 features inversion dimers.

The first metal complexes comprising amidino-guanidinate ligands have been prepared and structurally characterized, namely bis-[μ- N , N ', N '', N '''-tetraisopropyl-1-(1-butyl-amidinato)guanidinato-κ 3 N 1 , N 2 : N 2 ]bis-[(tetra-hydro-furan)lithium], [Li 2 (C 18 H 37 N 4 ) 2 (C 4 H 8 O) 2 ], ( 2 ), and [bis-(tetra-hydro-furan)-lithium]-di-μ-chlorido-{( N , N '-di-cyclo-hexyl-1-butyl-amidinato-κ 2 N 1 , N 2 )[ N , N ', N '', N '''-tetra-cyclo-hexyl-1-(1-butyl-amidinato)guanidinato-κ 2 N 1 , N 2 ]holmate(III)}, [HoLiCl 2 (C 4 H 8 O) 2 (C 17 H 31 N 2 )(C 30 H 53 N 4 )], ( 3 ). The novel lithium amidino-guanidinate precursors Li[ n BuC(=N R )(N R )C(N R ) 2 ] [ 1 : R = Cy (cyclo-hex-yl), 2 : R = i Pr) were obtained by treatment of N , N '-diorganocarbodi-imides, R -N=C=N- R ( R = i Pr, Cy), with 0.5 equivalents of n -butyl-lithium under well-defined reaction conditions. An X-ray diffraction study of 2 revealed a ladder-type dimeric structure in the solid state. Reaction of anhydrous holmium(III) chloride with in situ -prepared 2 afforded the unexpected holmium 'ate' complex [ n BuC(=NCy)(NCy)C(NCy) 2 ]Ho[ n BuC(NCy) 2 ](μ-Cl) 2 Li(THF) 2 ( 3 ) in 71% yield. An X-ray crystal structure determination of 3 showed that this complex contains both an amidinate ligand and the new amidino-guanidinate ligand.

The lithium-cyclopropylethynylamidinates Li[c-C3H5-C[triple bond, length as m-dash]C-C(NR)2] (1a: R = (i)Pr, 1b: R = cyclohexyl (Cy)) have been used as precursors for the preparation of five new series of half-sandwich complexes. These complexes contain the large flat cyclooctatetraenyl ligand (C8H8(2-), commonly abbreviated as COT), and were isolated as solvated, unsolvated and inverse sandwich complexes. Treatment of the halide precursors [(COT)Pr(μ-Cl)(THF)2]2 with 1b and [(COT)Nd(μ-Cl)(THF)2]2 with 1a and 1b in THF in a 1 : 2 molar ratio, respectively, afforded (COT)Ln[μ-c-C3H5-C[triple bond, length as m-dash]C-C(NR)2]2Li(L) (2: Ln = Pr, R = Cy, L = Et2O; 3: Ln = Nd, R = (i)Pr, L = THF; 4: Ln = Nd, R = Cy, L = THF). Treatment of the dimeric cerium(iii) bis(cyclopropylethynylamidinate) complexes [{c-C3H5-C[triple bond, length as m-dash]C-C(NR)2}2Ce(μ-Cl)(THF)]2 (5: R = (i)Pr; 6: R = Cy) in situ with K2C8H8 in a 1 : 1 molar ratio in THF at room temperature afforded the inverse-sandwich complexes (μ-η(8):η(8)-COT)[Ce{c-C3H5-C[triple bond, length as m-dash]C-C(NR)2}2]2 (7: R = (i)Pr; 8: R = Cy). This reaction represents a new method for encapsulation of a planar (C8H8)(2-) ring in lanthanide complexes containing amidinate ligands in the outer decks. Novel unsolvated dinuclear lanthanide half-sandwich complexes were prepared by using the precursors 1a, 1b and COT(2-). Unlike the complexes 2-4, the reaction of [(COT)Pr(μ-Cl)(THF)2]2 with 1a afforded the unsolvated centrosymmetric complex [(COT)Pr(μ-c-C3H5-C[triple bond, length as m-dash]C-C(N(i)Pr)2)]2 (9). These dimeric structures could be also accessed by reaction of LnCl3 (Ln = Ce or Nd) with 1a or 1b and K2COT in a 1 : 1 : 1 molar ratio as a one-pot reaction to give novel [(COT)Ln(μ-c-C3H5-C[triple bond, length as m-dash]C-C(NR)2)]2 complexes (10: Ln = Ce, R = (i)Pr; 11: Ln = Ce, R = Cy; 12: Ln = Nd, R = (i)Pr). Similar treatment of HoCl3 with 1a or 1b and K2COT as three-component reactions in a 1 : 1 : 1 molar ratio afforded the solvated half-sandwich complexes (COT)Ho(c-C3H5-C[triple bond, length as m-dash]C-C(NR)2)(THF) (13: R = (i)Pr; 14: R = Cy). A unique multidecker sandwich complex [(μ-η(8):η(8)-COT){Nd(c-C3H5-C[triple bond, length as m-dash]C-C(NCy)2)(μ-Cl)}2]4 (15) was prepared by reaction of anhydrous NdCl3 with K2COT and 1b in a one-pot reaction. The solid state structure of 15 revealed the presence of an unprecedented macrocyclic sandwich compound ("giant neodymium wheel") consisting of four COT rings sandwiched between eight Nd(3+) ions, and each Nd(3+) ion is bonded to one amidinate ligand and bridged by two chlorine atoms with the neighbouring Nd(3+) ion.

Two ytterbium(III) complexes comprising alkynylamidinate ligands, namely bis-(η 5 -cyclo-penta-dien-yl)(3-cyclo-propyl- N , N '-diiso-propyl-propynamidinato-κ 2 N , N ')ytterbium(III), [Yb(C 5 H 5 ) 2 (C 12 H 19 N 2 )] or Cp 2 Yb[( i Pr 2 N) 2 C-C≡C- c -C 3 H 5 ] ( 1 ) and tris-(3-phenyl- N , N '-di-cyclo-hexyl-propynamidinato-κ 2 N , N ')ytterbium(III), [Yb(C 21 H 27 N 2 ) 3 ] or Yb[(CyN) 2 C-C≡C-Ph] 3 (Cy = cyclo-hex-yl) ( 2 ) have been synthesized and structurally characterized. Both complexes are monomers; for complex 2 , the contribution to the scattering from highly disordered toluene solvent molecules in these voids was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C 71 , 9-18] in PLATON . The stated crystal data for Mr , μ etc . do not take these into account.

Well-defined lanthanide polysulfide complexes containing S4(2-) and S5(2-) ligands, the samarium(iii) pentasulfide complex Sm(Tp(iPr2))(κ(1)-3,5-(i)Pr2Hpz)(S5) and the tetrasulfide-bridged binuclear ytterbium(iii) complex (μ-S4)[Yb(Tp(iPr2))(κ(1)-3,5-(i)Pr2Hpz)(κ(2)-3,5-(i)Pr2pz)]2 (Tp(iPr2) = hydro-tris(3,5-diisopropylpyrazolyl)borate), have been synthesized and structurally characterized by single-crystal X-ray diffraction.

This Tutorial Review presents an overview on the synthesis, characterization and applications of metal complexes containing curcumin (=1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) and its derivatives as ligands. Innovative synthetic strategies leading to soluble and crystallizable metal curcumin complexes are outlined in detail. Special emphasis is placed on the highly promising and exciting medicinal applications of metal curcumin complexes, with the three most important areas being anticancer activity and selective cytotoxicity, anti-Alzheimer's disease activity, and antioxidative/neuroprotective effects. Overall, this Tutorial Review provides the first general overview of this emerging and rapidly expanding field of interdisciplinary research.

Asymmetric ASH1 mRNA transport during mitosis of budding yeast constitutes one of the best-studied examples of mRNA localization. Recently, 2 studies used in vitro motility assays to prove that motile ASH1 mRNA-transport complexes can be reconstituted entirely from recombinant factors. Both studies, however, differed in their conclusions on whether cargo RNA itself is required for particle assembly and thus activation of directional transport. Here we provide direct evidence that stable complexes do assemble in absence of RNA at physiologic conditions and even at ionic strengths above cellular levels. These results directly confirm the previous notion that the ASH1 transport machinery is not activated by the cargo RNA itself, but rather through protein-protein interactions.

The title salt, [Pd(C3H4N2)4]Cl2, was obtained unexpectedly by the reaction of palladium(II) dichloride with equimolar amounts of 1-chloro-1-nitro-2,2,2-tris-(pyrazol-yl)ethane in methanol solution. The Pd(2+) cation is located on an inversion centre and has a square-planar coordination sphere defined by four N atoms of four neutral pyrazole ligands. The average Pd-N distance is 2.000 (2) Å. The two chloride anions are not coordinating to Pd(2+). They are connected to the complex cations through N-H⋯Cl hydrogen bonds. In addition, C-H⋯Cl hydrogen bonds are observed, leading to a three-dimensional linkage of cations and anions.

An unprecedented deboronation reaction of icosahedral carboranes is described, in which a BH group of m-carborane is detached from the cage and incorporated into an unusual nido-carborane-anellated diazadiborepine ring system.

This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect.

The title compound, 1-carbamoylguanidinium bis-(2,4,6-tri-nitro-phen-yl)amide [H2NC(=O)NHC(NH2)2](+)[N{C6H2(NO2)3-2,4,6}2](-) (= guanylurea dipicryl-amide), was prepared as dark-red block-like crystals in 70% yield by salt-metathesis reaction between guanylurea sulfate and sodium dipicryl-amide. In the solid state, the new compound builds up an array of mutually linked guanylurea cations and dipicryl-amide anions. The crystal packing is dominated by an extensive network of N-H⋯O hydrogen bonds, resulting in a high density of 1.795 Mg m(-3), which makes the title compound a potential secondary explosive.

Mono- and dianionic carboranylamidinates are readily available in one-pot reactions directly from o-carborane (1). In situ-monolithiation of 1 followed by treatment with N,N'-diisopropylcarbodiimide, (i)PrN=C=N(i)Pr, or N,N'-dicyclohexylcarbodiimide, CyN=C=NCy, provided the lithium carboranylamidinates (o-C2B10H10C(NH(i)Pr)(=N(i)Pr)-κ(2)C,N)Li(DME) (2a) and (o-C2B10H10C(NH(i)Cy)(=N(i)Cy)-κ(2)C,N)Li(THF)2 (2b). Controlled hydrolysis of 2a,b afforded the free carboranylamidines o-C2B10H11C(NH(i)R)(=N(i)R) (3a: R = (i)Pr, 3b: R = Cy). The first dimetalated carboranylamidinates, o-C2B10H10C(N(i)Pr)(=N(i)Pr)Li2(DME)2 (4a) (DME = 1,2-dimethoxyethane) and o-C2B10H10C(N(i)Pr)(=N(i)Pr)Li2(THF)4 (4b), were prepared in high yield (83% yield) directly from 1 using a simple one-pot synthetic protocol. Treatment of 4b with 2 equiv. of Me3SiCl afforded the disilylated derivative o-C2B10H10-κ(2)C,N-[C(N(i)PrSiMe3)(=N(i)Pr)]SiMe3 (5). Dianionic 4b also served as an excellent precursor for novel inorganic heterocycles incorporating the closo-1,2-C2B10H10 cage, including the unsymmetrical distannene [o-C2B10H10C(N(i)Pr)(=N(i)Pr)-κ(2)C,N]Sn=Sn[((i)PrN)2C(n)Bu]2 (6) and the azaphosphole derivative [o-C2B10H10C(N(i)Pr)(=N(i)Pr)-κ(2)C,N]PPh (7). Surprisingly, it was found that the synthesis of new inorganic ring systems from dianionic carboranylamidinates can also be achieved by employing only 1 equiv. of n-butyllithium in the generation of the anionic carboranylamidinate intermediates. Using this straightforward one-pot synthetic protocol, the Group 14 metallacycles [o-C2B10H10C(NCy)(=NCy)-κ(2)C,N]SiR2 (R = Cl (8), Me (9), Ph (10)) and [o-C2B10H10C(NCy)([=NCy)-κ(2)C,N]GeCl2 (11) have become accessible. The same synthetic strategy could be successfully adapted to prepare the corresponding Group 4 metallocene derivatives Cp2Ti[o-C2B10H10C(NCy)(=NCy)-κ(2)C,N] (12) and Cp2Zr[o-C2B10H10C(NCy)(=NCy)-κ(2)C,N] (13). The molecular structures of 2b, 3b, 4b, 5, 6, 7, 10, 12, and 13 were confirmed by single-crystal X-ray diffraction.

Reconstitution of protein complexes has been a valuable tool to test molecular functions and to interpret in vivo observations. In recent years, a large number of RNA-protein complexes has been identified to regulate gene expression and to be important for a range of cellular functions. In contrast to protein complexes, in vitro analyses of RNA-protein complexes are hampered by the fact that recombinant expression and purification of RNA molecules is more difficult and less well established than for proteins. Here we review the current state of technology available for in vitro experiments with RNAs. We outline the possibilities to produce and purify large amounts of homogenous RNA and to perform the required quality controls. RNA-specific problems such as degradation, 5' and 3' end heterogeneity, co-existence of different folding states, and prerequisites for reconstituting RNAs with recombinantly expressed proteins are discussed. Additionally a number of techniques for the characterization of direct and indirect RNA-protein interactions are explained., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)

Asymmetric, motor-protein dependent transport of mRNAs and subsequent localized translation is an important mechanism of gene regulation. Due to the high complexity of such motile particles, our mechanistic understanding of mRNA localization is limited. Over the last two decades, ASH1 mRNA localization in budding yeast has served as comparably simple and accessible model system. Recent advances have helped to draw an increasingly clear picture on the molecular mechanisms governing ASH1 mRNA localization from its co-transcriptional birth to its delivery at the site of destination. These new insights help to better understand the requirement of initial nuclear mRNPs, the molecular basis of specific mRNA-cargo recognition via cis-acting RNA elements, the different stages of RNP biogenesis and reorganization, as well as activation of the motile activity upon cargo binding. We discuss these aspects in context of published findings from other model organisms.

The assembly and composition of ribonucleic acid (RNA)-transporting particles for asymmetric messenger RNA (mRNA) localization is not well understood. During mitosis of budding yeast, the Swi5p-dependent HO expression (SHE) complex transports a set of mRNAs into the daughter cell. We recombinantly reconstituted the core SHE complex and assessed its properties. The cytoplasmic precomplex contains only one motor and is unable to support continuous transport. However, a defined interaction with a second, RNA-bound precomplex after its nuclear export dimerizes the motor and activates processive RNA transport. The run length observed in vitro is compatible with long-distance transport in vivo. Surprisingly, SHE complexes that either contain or lack RNA cargo show similar motility properties, demonstrating that the RNA-binding protein and not its cargo activates motility. We further show that SHE complexes have a defined size but multimerize into variable particles upon binding of RNAs with multiple localization elements. Based on these findings, we provide an estimate of number, size, and composition of such multimeric SHE particles in the cell.

The title compound, [Ge2(C8H17N2)4O2], crystallizes with imposed twofold symmetry, which allows the monodentate amidinate ligands to be arranged in a cisoid fashion. The independent Ge-O distances within the central Ge2O2 ring, which is essentially planar (r.m.s. deviation = 0.039 Å), are 1.7797 (8) and 1.8568 (8) Å. The germanium centres adopt a distorted trigonal-bipyramidal geometry, being coordinated by the two O atoms and by one bidentate and one monodentate amidinate ligand (three N atoms). One N-isopropyl group is disordered over two positions; these are mutually exclusive because of 'collisions' between symmetry-equivalent methyl groups and thus each has 0.5 occupancy.

Five new homoleptic gadolinium tris-amidinate complexes are reported, which were synthesized via the salt-elimination reaction of GdCl(3) with 3 equiv of lithiated symmetric and asymmetric amidinates at ambient temperature. The Gd-tris-amidinates [Gd{(N(i)Pr)(2)CR}(3)] [R = Me (1), Et (2), (t)Bu (3), (n)Bu (4)] and [Gd{(NEt)(N(t)Bu)CMe}(3)] (5) are solids at room temperature and sublime at temperatures of about 125 °C (6 × 10(-2) mbar) with the exception of compound 4, which is a viscous liquid at room temperature. According to X-ray diffraction analysis of 3 and 5 as representative examples of the series, the complexes adopt a distorted octahedral structure in the solid state. Mass spectrometric (MS) data confirmed the monomeric structure in the gas phase, and high-resolution MS allowed the identification of characteristic fragments, such as [{(N(i)Pr)(2)CR}GdCH(3)](+) and [{(N(i)Pr)(2)CR}GdNH](+). The alkyl substitution patterns of the amidinate ligands clearly show an influence on the thermal properties, and specifically, the introduction of the asymmetric carbodiimide leads to a lowering of the onset of volatilization and decomposition. Compound 5, which is the first Gd complex with an asymmetric amidinate ligand system to be reported, was, therefore, tested for the MOCVD of GdN thin films. The as-deposited GdN films were capped with Cu in a subsequent MOCVD process to prevent postdeposition oxidation of the films. Cubic GdN on Si(100) substrates with a preferred orientation in the (200) direction were grown at 750 °C under an ammonia atmosphere and exhibited a columnar morphology and low levels of C or O impurities according to scanning electron microscopy, Rutherford backscattering, and nuclear reaction analysis.

Today the rare-earth elements play a critical role in numerous high-tech applications. This is why various areas of rare-earth chemistry are currently thriving. In organolanthanide chemistry the search for new ligand sets which are able to satisfy the coordination requirements of the large lanthanide cations continues to be a hot topic. Among the most successful approaches in this field is the use of amidinate and guanidinate ligands of the general types [RC(NR')(2)](-) (R = H, alkyl, aryl; R' = alkyl, cycloalkyl, aryl, SiMe(3)) and [R(2)NC(NR')(2)](-) (R = alkyl, SiMe(3); R' = alkyl, cycloalkyl, aryl, SiMe(3)), which can both be regarded as steric cyclopentadienyl equivalents. Mono-, di- and trisubstituted lanthanide amidinate and guanidinate complexes are all readily available. Various rare earth amidinates and guanidinates have turned out to be very efficient homogeneous catalysts e.g. for the polymerization of olefins and dienes, the ring-opening polymerization of cyclic esters or the guanylation of amines. Moreover, certain alkyl-substituted lanthanide tris(amidinates) and tris(guanidinates) were found to be highly volatile and are thus promising precursors for ALD (= atomic layer deposition) and MOCVD (= metal-organic chemical vapor deposition) processes in materials science, e.g. for the production of lanthanide nitride thin layers. This tutorial review covers the continuing success story of lanthanide amidinates and guanidinates which have undergone an astonishing transition from mere laboratory curiosities to efficient homogeneous catalysts as well as ALD and MOCVD precursors within the past 10 years.

The title copper(II) N-pyrazolylpropanamide (PPA) complex, [CuBr(PPA)(2)]Br, was obtained in 78% yield by treatment of CuBr(2) with an excess of the ligand in methanol. Crystallization from the mother liquid afforded the title compound, i.e. the methanol solvate [CuBr(C(6)H(9)N(3)O)(2)]Br·CH(3)OH or [CuBr(PPA)(2)]Br·MeOH, as bright green crystals. In the solid state, the title salt comprises isolated [CuBr(PPA)(2)](+) cations, separated bromide ions and methanol of crystallization. In the cation, the central Cu(II) ion is coordinated by two N,O-chelating PPA ligands and one Br(-) ion. The coordination geometry around the Cu(II) ion is distorted trigonal-bipyramidal with the bromide ligand and the amide O atoms occupying the equatorial positions [Cu-Br = 2.4443 (4) Å; Cu-O = 2.035 (2) and 2.179 (2) Å], while the pyrazole N atoms coordinate in the axial positions [Cu-N = 1.975 (2) and 1.976 (2) Å]. In the crystal, the three constituents are linked by N-H⋯Br, O-H⋯Br, and N-H⋯O hydrogen bonds, forming a three-dimensional network.

Hsc70 is a conserved ATP-dependent molecular chaperone, which utilizes the energy of ATP hydrolysis to alter the folding state of its client proteins. In contrast to the Hsc70 systems of bacteria, yeast and humans, the Hsc70 system of C. elegans (CeHsc70) has not been studied to date.We find that CeHsc70 is characterized by a high ATP turnover rate and limited by post-hydrolysis nucleotide exchange. This rate-limiting step is defined by the helical lid domain at the C-terminus. A certain truncation in this domain (CeHsc70-Δ545) reduces the turnover rate and renders the hydrolysis step rate-limiting. The helical lid domain also affects cofactor affinities as the lidless mutant CeHsc70-Δ512 binds more strongly to DNJ-13, forming large protein complexes in the presence of ATP. Despite preserving the ability to hydrolyze ATP and interact with its cofactors DNJ-13 and BAG-1, the truncation of the helical lid domain leads to the loss of all protein folding activity, highlighting the requirement of this domain for the functionality of the nematode's Hsc70 protein.

The use of the superbulky cyclooctatetraenide dianion ligand [C(8)H(6)(SiPh(3))(2)](2-) (= COT(BIG)) in organo-f-element chemistry leads to unprecedented effects such as the formation of a significantly bent anionic Ce(III) sandwich complex, a novel cerocene formed by sterically induced SiPh(3) group migration, as well as the first example of a bent uranocene.

The title compound, [Sm(C(25)H(35)N(2))(C(14)H(24)Si(2))(C(4)H(8)O)]·C(7)H(8), was prepared by treatment of anhydrous samarium trichloride with a 1:1 mixture of in situ-prepared Li(DippForm) [DippFormH = N,N'-bis-(2,6-diisopropyl-phen-yl)methanimidamide] and Li(2)(COT'') [COT'' = 1,4-bis-(trimethyl-sil-yl)cyclo-octa-tetra-enyl] in tetra-hydro-furan (THF). Despite the presence of two very bulky ligands (COT'' and DippForm), the mol-ecule still contains one coordinated THF ligand. The overall coordination geometry around the Sm(III) atom resembles a three-legged piano-stool with the COT'' ligand being η(8)-coordinated and the DippForm(-) anion acting as an N,N'-chelating ligand [Sm-N = 2.5555 (15) and 2.4699 (15) Å]. The asymmetric unit also contains a disordered mol-ecule of toluene, the refined ratio of the two components being 0.80 (4):0.20 (4).

Carboranylamidinate anions are readily accessible via addition of N,N'-dialkylcarbodiimides to lithio-ortho-carborane. They represent a novel difunctional boron-rich ligand system for main group and transition elements (Li, Sn, Cr). Initial structural investigations revealed an unexpected N,C-coordination mode instead of N,N'-chelation.

The title compound, [Ce(C(13)H(19)N(2))(3)], was obtained in moderate yield (67%) by treatment of anhydrous cerium trichloride with three equivalents of Li[PhC(N(i)Pr)(2)] in tetra-hydro-furan. It is the first homoleptic lanthanide complex of this amidinate ligand. The central Ce(III) ion is coordinated by three chelating benzamidinate anions in a distorted octa-hedral fashion, with Ce-N distances in the narrow range 2.482 (2)-2.492 (2) Å. The dihedral angles between the phenyl rings and the chelating N-C-N units are in the range 73.3-87.9°, thus preventing conjugation between the two π-systems. The mol-ecule is located on a twofold rotation axis, and one of the phenyl rings is equally disordered over two alternative symmetry-equivalent positions around this axis.