Scandium-Mediated Formation of a Bis(tetrahydropentalene)

The reactivity of Li[Sc(COT′′)₂] ( 1 ; COT′′=1,4-bis(trimethylsilyl)cyclooctatetraenyl) towards CoCl₂ is considerably different from that of related lanthanide triple-decker sandwich complexes. In addition to the expected triple-decker complex Sc₂(COT′′)₃ ( 2 ), the complex Sc₂{μ-BTHP}(COT′′)₂ ( 3 ) is formed, which comprises the novel BTHP²⁻ ligand (BTHP²⁻=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, C₁₆H₁₀(SiMe₃)₄²⁻). The formation of 3 is likely facilitated by the fact that scandium prefers η⁸,η³ coordination rather than highly symmetric η⁸,η⁸ coordination, and the η³-coordinated COT′′ ligand in 1 is activated owing to a loss of aromaticity. Acid hydrolysis of 3 leads to air-stable H₂BTHP ( 4 ).     

A Structurally Characterized Organometallic Plutonium(IV) Complex

The blood‐red plutonocene complex Pu(1,3‐COT′′)(1,4‐COT′′) ( 4 ; COT′′=η⁸‐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.     

Synthesis and Structural Characterization of New Zirconium(IV) Bent Metallocenes comprising η8‐Cyclooctatetraenyl and Bulky Cyclopentadienyl Ligands

The new zirconium bent metallocenes (COT)Zr(Cp^tBu2)Cl ( 1 ) and (COT)Zr(Cp′′)Cl ( 2 ) were synthesized in a straightforward manner and in high yields ( 1 : 91 %, 2 : 86 %) by treatment of in situ‐prepared (COT)ZrCl₂(THF) with 1 equiv. of K(Cp^tBu2) or K(Cp′′), respectively (COT = η⁸‐cyclooctatetraenyl; Cp^tBu2 = η⁵‐1,3‐di‐tert‐butylcyclopentadienyl; Cp′′ = η⁵‐1,3‐bis(trimethylsilyl)cyclopentadienyl). Subsequent reaction of 1 with 1 equiv. of phenyllithium afforded the σ‐phenyl derivative (Cp^tBu2)Zr(COT)Ph ( 3 ) as orange crystals in 83 % isolated yield. All three new compounds were structurally characterized through single‐crystal X‐ray diffraction.     

The dinuclear scandium(III) cyclooctatetraenyl chloride complex di‐μ‐chlorido‐bis[(η8‐cyclooctatetraene)(tetrahydrofuran‐κO)scandium(III)]

Only a few cyclooctatetraene dianion (COT) π‐complexes of lanthanides have been crystallographically characterized. This first single‐crystal X‐ray diffraction characterization of a scandium(III) COT chloride complex, namely di‐μ‐chlorido‐bis[(η⁸‐cyclooctatetraene)(tetrahydrofuran‐κO )scandium(III)], [Sc₂(C₈H₈)₂Cl₂(C₄H₈O)₂] or [Sc(COT)Cl(THF)]₂ (THF is tetrahydrofuran), (1), reveals a dimeric molecular structure with symmetric chloride bridges [average Sc—Cl = 2.5972 (7) Å] and a η⁸‐bound COT ligand. The COT ring is planar, with an average C—C bond length of 1.399 (3) Å. The Sc—C bond lengths range from 2.417 (2) to 2.438 (2) Å [average 2.427 (2) Å]. Direct comparison of (1) with the known lanthanide (Ln) analogues (La, Ce, Pr, Nd, and Sm) illustrates the effect of metal‐ion (M ) size on molecular structure. Overall, the M —Cl, M —O, and M —C bond lengths in (1) are the shortest in the series. In addition, only one THF molecule completes the coordination environment of the small Sc^III ion, in contrast to the previously reported dinuclear Ln–COT–Cl complexes, which all have two bound THF molecules per metal atom.     

A halide‐free pyridinium‐substituted η3‐cycloheptatrienide–Pd complex

We report the synthesis and characterization of a novel 4‐(dimethylamino)pyridinium‐substituted η³‐cycloheptatrienide–Pd complex which is free of halide ligands. Diacetonitrile{η³‐[4‐(dimethylamino)pyridinium‐1‐yl]cycloheptatrienido}palladium(II) bis(tetrafluoroborate), [Pd(C₂H₃N)₂(C₁₄H₁₆N₂)](BF₄)₂, was prepared by the exchange of two bromide ligands for noncoordinating anions, which results in the empty coordination sites being occupied by acetonitrile ligands. As described previously, exchange of only one bromide leads to a dimeric complex, di‐μ‐bromido‐bis({η³‐[4‐(dimethylamino)pyridinium‐1‐yl]cycloheptatrienido}palladium(II)) bis(tetrafluoroborate) acetonitrile disolvate, [Pd₂Br₂(C₁₄H₁₆N₂)₂](BF₄)₂·2CH₃CN, with bridging bromide ligands, and the crystal structure of this compound is also reported here. The structures of the cycloheptatrienide ligands of both complexes are analogous to the dibromide derivative, showing the allyl bond in the β‐position with respect to the pyridinium substituent. This indicates that, unlike a previous interpretation, the main reason for the formation of the β‐isomer cannot be internal hydrogen bonding between the cationic substituents and bromide ligands.     

A Pd4Br4 macrocycle trapped by cocrystallization from a highly dynamic equilibrium of η3‐cycloheptatrienide complexes

In the coordination chemistry of palladium, dimers bridged via halides are a common motif. Higher oligomers, however, are still rare. We report the structure of an alternating eight‐membered [Pd₄Br₄]⁴⁻ ring framed by cycloheptatrienide ligands, which was obtained by cocrystallization of dimers and tetramers of the complex salt bromido{η³‐[3‐(2,6‐diisopropylphenyl)imidazolium‐1‐yl]cycloheptatrienido}palladium(II) tetrafluoroborate, namely bis[di‐μ‐bromido‐bis({η³‐[3‐(2,6‐diisopropylphenyl)imidazolium‐1‐yl]cycloheptatrienido}palladium(II))] cyclo‐tetra‐μ‐bromido‐tetrakis({η³‐[3‐(2,6‐diisopropylphenyl)imidazolium‐1‐yl]cycloheptatrienido}palladium(II)) octakis(tetrafluoroborate) dichloromethane octasolvate, [Pd₄Br₄(C₂₂H₂₆N₂)₄][Pd₂Br₂(C₂₂H₂₆N₂)₂]₂(BF₄)₈·8CH₂Cl₂. These dimers and tetramers form a highly dynamic equilibrium in solution which was studied by low‐temperature NMR spectroscopy. In the light of the presented results, tetrameric Pd^II species can be assumed to co‐exist as a second species in many cases where by current knowledge only a dimeric compound would be expected.     

A three‐dimensional CdII coordination polymer constructed from 1,1′‐biphenyl‐2,2′,5,5′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands

The title coordination polymer, poly[[aqua(μ₅‐1,1′‐biphenyl‐2,2′,5,5′‐tetracarboxylato)bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]dicadmium(II)] dihydrate], {[Cd₂(C₁₆H₆O₈)(C₁₂H₁₀N₄)₂(H₂O)]·2H₂O}_n, was crystallized from a mixture of 1,1′‐biphenyl‐2,2′,5,5′‐tetracarboxylic acid (H₄bpta), 1,4‐bis(1H‐imidazol‐1‐yl)benzene (1,4‐bib) and cadmium nitrate in water–dimethylformamide. The crystal structure consists of two crystallographically independent Cd^II cations, with one of the Cd^II cations possessing a slightly distorted pentagonal bipyramidal geometry. The second Cd^II centre is coordinated by carboxylate O atoms and imidazole N atoms from two separate 1,4‐bib ligands, displaying a distorted octahedral CdN₂O₄ geometry. The completely deprotonated bpta⁴⁻ ligand, exhibiting a new coordination mode, bridges five Cd^II cations to form one‐dimensional chains viaμ₃‐η¹:η²:η¹:η² and μ₂‐η¹:η¹:η⁰:η⁰ modes, and these are further linked by 1,4‐bib ligands to form a three‐dimensional framework with a (4².6⁴)(4.6²)(4³.6⁵.7²) topology. The structure of the coordination polymer is reinforced by intermolecular hydrogen bonding between carboxylate O atoms, aqua ligands and crystallization water molecules. The solid‐state photoluminescence properties were investigated and the complex might be a candidate for a thermally stable and solvent‐resistant blue fluorescent material.     

meso‐Bis{η5‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}iron(II) and the cobalt(II) analogue

The two title crystalline compounds, viz.meso‐bis{η⁵‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}iron(II), [Fe(C₁₂H₂₀NSi)₂], (II), and meso‐bis{η⁵‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}cobalt(II), [Co(C₁₂H₂₀NSi)₂], (III), were obtained by the reaction of lithium 1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienide with FeCl₂ and CoCl₂, respectively. For (II), the trimethylsilyl‐ and dimethylaminoethenyl‐substituted cyclopentadienyl (Cp) rings present a nearly eclipsed conformation, and the two pairs of trimethylsilyl and dimethylaminoethenyl substituents on the Cp rings are arranged in an interlocked fashion. In the case of (III), the same substituted Cp rings are perfectly staggered leading to a crystallographically centrosymmetric molecular structure, and the two trimethylsilyl and two dimethylaminoethenyl substituents are oriented in opposite directions, respectively, with the trimethylsilyl group of one Cp ring and the dimethylaminoethenyl group of the other Cp ring arranged more closely than in (II).     

η2(π)‐Coordination of a Bis‐Phosphonio‐Benzophospholide Cation: A Novel Complexation Mode for Unsaturated Phosphorus Heterocycles

The bis‐phosphonio‐benzo[c]phospholide tetraphenylborate 4 [BPh₄] reacts with CpCo(C₂H₄)₂ to form a chelate complex [Co(η⁵–Cp)(κ²P,η²(P=C) –4 )][BPh₄] ( 6 [BPh₄]) which was characterized by means of spectroscopic techniques and a single crystal X‐ray diffraction study. The observed η²(π)‐coordination of the benzophospholide moiety in the cation 6 is highly unusual for aromatic phosphorus heterocycles. The structural data suggest a pronounced coordination‐induced localization of π‐electrons in the condensed ring system.     

π‐Ruthenium Complexes of Hexaphyrins(1.1.1.1.1.1): A Triple‐Decker Complex Bearing Two Ruthenoarene Units

Ruthenium(II) π‐coordination onto [28]hexaphyrins(1.1.1.1.1.1) has been accomplished. Reactions of bis‐Au^III and mono‐Au^III complexes of hexakis(pentafluorophenyl) [28]hexaphyrin with [RuCl₂(p‐cymene)]₂ in the presence of NaOAc gave the corresponding π‐ruthenium complexes, in which the [(p‐cymene)Ru]^II fragment sat on the deprotonated side pyrrole. A similar reaction of the bis‐Pd^II [26]hexaphyrin complex afforded a triple‐decker complex, in which the two [(p‐cymene)Ru]^II fragments sat on both sides of the center of the [26]hexaphyrin framework.     

Oxidation Chemistry of Inorganic Benzene Complexes

The oxidation of the 28 VE cyclo‐E₆ triple‐decker complexes [(Cp^RMo)₂(μ,η⁶:η⁶‐E₆)] (E=P, Cp^R=Cp( 2 a ), Cp*( 2 b ), Cp^Bn( 2 c )=C₅(CH₂Ph)₅; E=As, Cp^R=Cp*( 3 )) by Cu⁺ or Ag⁺ leads to cationic 27 VE complexes that retain their general triple‐decker geometry in the solid state. The obtained products have been characterized by cyclic voltammetry (CV), EPR, Evans NMR, multinuclear NMR spectroscopy, MS, and structural analysis by single‐crystal X‐ray diffraction. The cyclo‐E₆ middle decks of the oxidized complexes are distorted to a quinoid ( 2 a ) or bisallylic ( 2 b , 2 c , 3 ) geometry. DFT calculations of 2 a , 2 b , and 3 persistently result in the bisallylic distortion as the minimum geometry and show that the oxidation leads to a depopulation of the σ‐system of the cyclo‐E₆ ligands in 2 a – 3 . Among the starting complexes, 2 c is reported for the first time including its preparation and full characterization.     

Reaction of vanadocene and vanadocene dichloride with ortho-iodobenzoic acid

At the interaction of bis (η⁵-cyclopentadienyl)vanadium with iodobenzoic acid or trimethylsilyl o-iodobenzoate in toluene depending on the ratio of the initial reagents bis(η⁵-cyclopentadienyl)vanadium(o-iodobenzoate) or η⁵-cyclopentadienylvanadium-bis-o-iodobenzoate were obtained in high yields. The latter was also formed in the reaction of bis(η⁵-cyclopentadiene)vanadium dihloride with trimethylsilyl o-iodobenzoate.     

Size-determining dependencies in supramolecular organometallic host-guest chemistry

Treatment of the pentaphosphaferrocene [Cp*Fe(η⁵‐P₅)] with Cu^I halides in the presence of different templates leads to novel fullerene‐like spherical molecules that serve as hosts for the templates. If ferrocene is used as the template the 80‐vertex ball [Cp₂Fe]@[{Cp*Fe(η⁵‐P₅)}₁₂{CuCl}₂₀] ( 4 ), with an overall icosahedral C₈₀ topological symmetry, is obtained. This result shows the ability of ferrocene to compete successfully with the internal template of the reaction system [Cp*Fe(η⁵‐P₅)], although the 90‐vertex ball [{Cp*Fe(η⁵:η¹:η¹:η¹:η¹:η¹‐P₅)}₁₂(CuCl)₁₀(Cu₂Cl₃)₅{Cu(CH₃CN)₂}₅] ( 2 a ) containing pentaphosphaferrocene as a guest is also formed as a byproduct. With use of the triple‐decker sandwich complex [(CpCr)₂(μ,η⁵‐As₅)] as a template the reaction between [Cp*Fe(η⁵‐P₅)] and CuBr leads to the 90‐vertex ball [(CpCr)₂(μ,η⁵‐As₅)]@[{Cp*Fe(η⁵‐P₅)}₁₂{CuBr}₁₀{Cu₂Br₃}₅{Cu(CH₃CN)₂}₅] ( 6 ), in which the complete molecule acts as a template. However, if the corresponding reaction is instead carried out with CuCl, cleavage of the triple‐decker complex is found and the 80‐vertex ball [CpCr(η⁵‐As₅)]@[{Cp*Fe(η⁵‐P₅)}₁₂{CuCl}₂₀] ( 5 ) is obtained. This accommodates as its guest [CpCr(η⁵‐As₅)], which has only 16 valence electrons in a triplet ground state and is not known as a free molecule. The triple‐decker sandwich complex [(CpCr)₂(μ,η⁵‐As₅)] requires 53.1 kcal mol^?1 to undergo cleavage (as calculated by DFT methods) and therefore this reaction is clearly endothermic. All new products have been characterized by single‐crystal X‐ray crystallography. A favoured orientation of the guest molecules inside the host cages has been identified, which shows π???π stacking of the five‐membered rings (Cp and cyclo‐As₅) of the guests and the cyclo‐P₅ rings of the nanoballs of the hosts.     

A three‐dimensional mixed‐valence CuII/CuI coordination polymer constructed from biphenyl‐3,4′,5‐tricarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands

Coordination polymers (CPs) built by coordination bonds between metal ions/clusters and multidentate organic ligands exhibit fascinating structural topologies and potential applications as functional solid materials. The title coordination polymer, poly[diaquabis(μ₄‐biphenyl‐3,4′,5‐tricarboxylato‐κ⁴O³:O^3′:O^4′:O⁵)tris[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]dicopper(II)dicopper(I)], [Cu^II₂Cu^I₂(C₁₅H₇O₆)₂(C₁₂H₁₀N₄)₃(H₂O)₂]_n, was crystallized from a mixture of biphenyl‐3,4′,5‐tricarboxylic acid (H₃bpt), 1,4‐bis(1H‐imidazol‐1‐yl)benzene (1,4‐bib) and copper(II) chloride in a water–CH₃CN mixture under solvothermal reaction conditions. The asymmetric unit consists of two crystallographically independent Cu atoms, one of which is Cu^II, while the other has been reduced to the Cu^I ion. The Cu^II centre is pentacoordinated by three O atoms from three bpt³⁻ ligands, one N atom from a 1,4‐bib ligand and one O atom from a coordinated water molecule, and the coordination geometry can be described as distorted trigonal bipyramidal. The Cu^I atom exhibits a T‐shaped geometry (CuN₂O) coordinated by one O atom from a bpt³⁻ ligand and two N atoms from two 1,4‐bib ligands. The Cu^II atoms are extended by bpt³⁻ and 1,4‐bib linkers to generate a two‐dimensional network, while the Cu^I atoms are linked by 1,4‐bib ligands, forming one‐dimensional chains along the [20] direction. In addition, the completely deprotonated μ₄‐η¹:η¹:η¹:η¹ bpt³⁻ ligands bridge one Cu^I and three Cu^II cations along the a (or [100]) direction to form a three‐dimensional framework with a (10³)₂(10)₂(4².6.10².12)₂(4².6.8².10)₂(8) topology via a 2,2,3,4,4‐connected net. An investigation of the magnetic properties indicated a very weak ferromagnetic behaviour.     

Scandium complexes with the tetraphenylethylene and anthracene dianions

The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare‐earth metal–carbon bonding. The crystal structures of (18‐crown‐6)bis(tetrahydrofuran‐κO)sodium bis(η⁶‐1,1,2,2‐tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C₄H₈O)₂(C₁₂H₂₄O₆)][Sc(C₂₆H₂₀)₂]·2C₄H₈O or [Na(18‐crown‐6)(THF)₂][Sc(η⁶‐C₂Ph₄)₂]·2(THF), ( 1b ), (η⁵‐1,3‐diphenylcyclopentadienyl)(tetrahydrofuran‐κO)(η⁶‐1,1,2,2‐tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C₁₇H₁₃)(C₂₆H₂₀)(C₄H₈O)]·0.5C₇H₈ or [(η⁵‐1,3‐Ph₂C₅H₃)Sc(η⁶‐C₂Ph₄)(THF)]·0.5(toluene), ( 5b ), poly[[(μ₂‐η³:η³‐anthracenediyl)bis(η⁶‐anthracenediyl)bis(η⁵‐1,3‐diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K₂Sc₂(C₁₄H₁₀)₃(C₁₇H₁₃)₂(C₄H₈O)₄]·C₄H₈O}_n or [K(THF)₂]₂[(1,3‐Ph₂C₅H₃)₂Sc₂(C₁₄H₁₀)₃]·THF, ( 6 ), and 1,4‐diphenylcyclopenta‐1,3‐diene, C₁₇H₁₄, ( 3a ), have been established. The [Sc(η⁶‐C₂Ph₄)₂]⁻ complex anion in ( 1b ) contains the tetraphenylethylene dianion in a symmetrical bis‐η³‐allyl coordination mode. The complex homoleptic [Sc(η⁶‐C₂Ph₄)₂]⁻ anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The 1D ¹H and ¹³C{¹H}, and 2D COSY ¹H–¹H and ¹³C–¹H NMR data are presented for M[Sc(Ph₄C₂)₂]·xTHF [M = Na and x = 4 for ( 1a ); M = K and x = 3.5 for ( 2a )] in THF‐d₈ media. Complex ( 5b ) exhibits an unsymmetrical bis‐η³‐allyl coordination mode of the dianion, but this changes to a η⁴ coordination mode for (1,3‐Ph₂C₅H₃)Sc(Ph₄C₂)(THF)₂, ( 5a ), in THF‐d₈ solution. A ⁴⁵Sc NMR study of ( 2a ) and UV–Vis studies of ( 1a ), ( 2a ) and ( 5a ) indicate a significant covalent contribution to the Sc—Ph₄C₂ bond character. The unique Sc ate complex, ( 6 ), contains three anthracenide dianions demonstrating both a η⁶‐coordination mode for two bent ligands and a μ₂‐η³:η³‐bridging mode of a flat ligand. Each [(1,3‐Ph₂C₅H₃)₂Sc₂(C₁₄H₁₀)₃]²⁻ dianionic unit is connected to four neighbouring units via short contacts with [K(THF)₂]⁺ cations, forming a two‐dimensional coordination polymer framework parallel to (001).     

Synthese,Struktur und Reaktivität von η1und η3‐Allyl‐Rhenium‐Carbonylen

Synthesis, Structure, and Reactivity of η¹‐ and η³‐Allyl Rhenium Carbonyls In (η³‐C₃H₅)Re(CO)₄ one CO ligand can be substituted by PPh₃, pyridine, isocyanide and benzonitrile. With 1,2‐bis(diphenylphosphino)ethylene, 1,1′‐bis(diphenylphosphino)ferrocene and 1,2‐bis(4‐pyridyl)ethane dinuclear ligand bridged complexes are obtained. The η³‐η¹ conversion of the allyl ligand occurs on reaction of (η³‐C₃H₅)Re(CO)₄ with the bidendate ligands 1,2‐bis(diphenylphosphino)ethane and 1,3‐bis(diphenylphosphino)propane and with 2,2′‐bipyridine (L–L) which gives the complexes (η¹‐C₃H₅)Re(CO)₃(L–L). By reaction of (η³‐C₃H₅)Re(CO)₄ with bis(diphenylphosphino)methane the allyl group is protonated and under elemination of propene the complex (OC)₃Re(Ph₂PCHPPh₂)(η¹‐Ph₂PCH₂PPh₂) ( 19 ) with a diphosphinomethanide ligand is formed. On heating solutions of (η³‐C₃H₅)Re(CO)₄ and (η³‐C₃H₅)Re(CO)₃(CN‐2,5‐Me₂C₆H₃) ( 5 ) in methanol the methoxy bridged compounds Re₄(CO)₁₂(OH)(OMe)₃ and Re₂(CO)₄(CN‐2,5‐Me₂C₆H₃)₄(μ‐OMe)₂ ( 20 ) were isolated. The crystal structures of (η³‐C₃H₅)Re(CO)₃(CNCH₂SiMe₃) ( 4 ), [(η³‐C₃H₅)(OC)₃Re]₂‐ (μ‐bis‐(diphenylphosphino)ferrocene) ( 8 ), (η¹‐C₃H₅)Re(CO)₃‐ (bpy) ( 14 ), of 19 , 20 and of (OC)₃Re‐[Ph₂P(CH₂)₃PPh₂]Cl ( 16 ) were determined by X‐ray diffraction.     

Synthesis,Crystal Structure,and Emission Spectra of Lanthanum(III) Coordination Polymer with 1,5‐Naphthalenedisulfonate Ligand

The first two‐dimensional lanthanum(III) coordination polymer, [La(1,5‐NDS)_1.5(H₂O)₅]_n (1) (1,5‐NDS^2? = 1,5‐naphthalenedisulfonate), was synthesized and structurally characterized by single‐crystal X‐ray diffraction analysis. The disulfonate ligands act in the η¹:η¹:μ₂ and η¹:η¹:η¹:μ₃ binding modes to link the LaO₉ tricapped trigonal prisms into a lamellar structure. It exhibits strong purple emission in the solid state.     

Synthesis,Reactivity, and Crystal Structure of the η2‐Thiocarbamoyl Palladium Complex [Pd(PPh3)2(η2‐SCNMe2)][PF6]

The η¹‐thiocarbamoyl palladium complexes [Pd(PPh₃)(η¹‐SCNMe₂)(η²‐S₂R)] (R = P(OEt)₂, 2 ; CNEt₂, 3 ) and trans‐[Pd(PPh₃)₂(η¹‐SCNMe₂)(η¹‐Spy)], 4 , (pyS: pyridine‐2‐thionate) are prepared by reacting the η²‐thiocarbamoyl palladium complex [Pd(PPh₃)₂(η²‐SCNMe₂)][PF₆], 1 with (EtO)₂PS₂NH₄, Et₂NCS₂Na, and pySK in methanol at room temperature, respectively. Treatment of 1 with dppm (dppm: bis(diphenylphosphino)methane) in dichloromethane at room temperature gives complex [Pd(PPh₃)(η¹‐SCNMe₂)(η²‐dppm)] [PF₆], 5 . All of the complexes are identified by spectroscopic methods and complex 1 is determined by single‐crystal X‐ray diffraction.     

Construction and photoluminescence properties of a three‐dimensional ZnII coordination network based on naphthalene‐1,4‐dicarboxylic acid and 1,6‐bis(pyridin‐3‐yl)‐1,3,5‐hexatriene

In recent years, coordination polymers constructed from multidentate carboxylate and pyridyl ligands have attracted much attention because these ligands can adopt a rich variety of coordination modes and thus lead to the formation of crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[μ₂‐1,6‐bis(pyridin‐3‐yl)‐1,3,5‐hexatriene‐κ²N:N′](μ₃‐naphthalene‐1,4‐dicarboxylato‐κ⁴O¹,O^1′:O⁴:O^4′)zinc(II)], [Zn(C₁₂H₆O₄)(C₁₆H₁₄N₂)]_n, has been prepared by the self‐assembly of Zn(NO₃)₂·6H₂O, naphthalene‐1,4‐dicarboxylic acid (1,4‐H₂ndc) and 1,6‐bis(pyridin‐3‐yl)‐1,3,5‐hexatriene (3,3′‐bphte) under hydrothermal conditions. The title compound has been structurally characterized by IR spectroscopy, elemental analysis, powder X‐ray diffraction and single‐crystal X‐ray diffraction analysis. Each Zn^II ion is six‐coordinated by four O atoms from three 1,4‐ndc²⁻ ligands and by two N atoms from two 3,3′‐bphte ligands, forming a distorted octahedral ZnO₄N₂ coordination geometry. Pairs of Zn^II ions are linked by 1,4‐ndc²⁻ ligands, leading to the formation of a two‐dimensional square lattice ( sql ) layer extending in the ab plane. In the crystal, adjacent layers are further connected by 3,3′‐bphte bridges, generating a three‐dimensional architecture. From a topological viewpoint, if each dinuclear zinc unit is considered as a 6‐connected node and the 1,4‐ndc²⁻ and 3,3′‐bphte ligands are regarded as linkers, the structure can be simplified as a unique three‐dimensional 6‐connected framework with the point symbol 4⁴6¹⁰8. The thermal stability and solid‐state photoluminescence properties have also been investigated.     

Magnetic Relaxation in Single‐Electron Single‐Ion Cerium(III) Magnets: Insights from Ab Initio Calculations

Detailed ab initio calculations were performed on two structurally different cerium(III) single‐molecule magnets (SMMs) to probe the origin of magnetic anisotropy and to understand the mechanism of magnetic relaxations. The complexes [Ce^III{Zn^II(L)}₂(MeOH)]BPh₄ ( 1 ) and [Li(dme)₃][Ce^III(cot′′)₂] ( 1 ; L=N,N,O,O‐tetradentate Schiff base ligand; 2 ; DME=dimethoxyethane, COT′′=1,4‐bis(trimethylsilyl)cyclooctatetraenyldianion), which are reported to be zero‐field and field‐induced SMMs with effective barrier heights of 21.2 and 30 K respectively, were chosen as examples. CASSCF+RASSI/SINGLE_ANISO calculations unequivocally suggest that m_J|±5/2〉 and |±1/2〉 are the ground states for complexes 1 and 2 , respectively. The origin of these differences is rooted back to the nature of the ligand field and the symmetry around the cerium(III) ions. Ab initio magnetisation blockade barriers constructed for complexes 1 and 2 expose a contrasting energy‐level pattern with significant quantum tunnelling of magnetisation between the ground state Kramers doublet in complex 2 . Calculations performed on several model complexes stress the need for a suitable ligand environment and high symmetry around the cerium(III) ions to obtain a large effective barrier.