7‐{Di­phenyl­[(tri­phenyl­phos­phine)­aurio]­phos­phine(1+)‐P}‐8‐methyl‐7,8‐dicarba‐nido‐undecaborate(1–) dichloro­methane hemi­solvate

The title compound, 7‐[(Ph₂P)Au(PPh₃)]‐8‐(CH₃)‐7,8‐nido‐C₂B₉H₁₀]·­0.5CH₂Cl₂ or [Au(C₁₅H₂₃B₉P)­(C₁₈H₁₅P)]·­0.5CH₂Cl₂, is the first reported gold derivative of the ligand [7‐­(Ph₂P)‐8‐(CH₃)‐7,8‐nido‐C₂B₉H₁₀]^?. It has a mono­nuclear structure with the gold centre in an essentially linear coordination [P—Au—P 174.041 (15)°]. The open C₂B₃ face contains one H atom that is strongly bonded to the central B atom and semi‐bridging to a neighbouring B atom [B—H distances 1.070 (16) and 1.45 (3) Å].     

Three monoalkoxy‐substituted nido‐platinaboranes: [(PPh3)2PtB10H11‐8‐(OCH3)], [(PPh3)2PtB10H11‐8‐{OCH(CH3)2}] and [(PPh3)2PtB10H10‐9‐{OCH(CH3)2}]

Each of the title compounds, 8‐methoxy‐7,7‐bis­(tri­phenyl­phosphine‐P)‐8,9:10,11‐di‐μH‐7‐platina‐nido‐undecaborane di­chloro­methane hemisolvate, [Pt(CH₁₄B₁₀O)(C₁₈H₁₅P)₂]·0.5CH₂Cl₂, (I), 8‐isopropoxy‐7,7‐bis­(tri­phenyl­phosphine‐P)‐8,9:10,11‐di‐μH‐7‐platina‐nido‐undecaborane di­chloro­methane solvate, [Pt(C₃H₁₈B₁₀O)(C₁₈H₁₅P)₂]·CH₂Cl₂, (II), and 9‐isopropoxy‐7,7‐bis­(tri­phenyl­phosphine‐P)‐8,9:10,11‐di‐μH‐7‐platina‐nido‐undecaborane di­chloro­methane solvate, [Pt(C₃H₁₈B₁₀O)(C₁₈H₁₅P)₂]·CH₂Cl₂, (III), has an 11‐vertex nido polyhedral skeleton, with the 7‐platinum centre ligating to two exo‐polyhedral PPh₃ groups and an alkoxy‐substituted polyhedral borane ligand. Compounds (II) and (III) are isomers. The Pt—B distances are in the range 2.214 (7)–2.303 (7) Å for (I), 2.178 (16)–2.326 (16) Å for (II) and 2.205 (6)–2.327 (6) Å for (III).     

η5‐(3)‐1‐Methyl‐1,2‐dicarbollyl‐η5‐2′,5′‐dimethylpyrrolylcobalt(III)

In the title compound, (η⁵‐2,5‐di­methyl­pyrrolyl)[(7,8,9,10,11‐η)‐7‐methyl‐7,8‐dicarba‐nido‐undecaborato]­cobalt(III), [3‐Co{η⁵‐[2,5‐(CH₃)₂‐NC₄H₂]}‐1‐CH₃‐1,2‐C₂B₉H₁₀] or [Co(C₃H₁₃B₉)(C₆H₈N)], the Co^III atom is sandwiched between the pentagonal faces of the pyrrolyl and dicarbollide ligands, resulting in a neutral mol­ecule. The C—C distance in the dicarbollide cage is 1.649 (3) Å.     

Dysprosiacarboranes as Organometallic Single‐Molecule Magnets

The dicarbollide ion, nido‐C₂B₉H₁₁^2? is isoelectronic with cyclopentadienyl. Herein, we make dysprosiacarboranes, namely [(C₂B₉H₁₁)₂Ln(THF)₂][Na(THF)₅] (Ln=Dy, 1Dy ) and [(THF)₃(μ‐H)₃Li]₂[{η⁵‐C₆H₄(CH₂)₂C₂B₉H₉}Dy{η²:η⁵‐C₆H₄(CH₂)₂C₂B₉H₉}₂Li] 3Dy and show that dicarbollide ligands impose strong magnetic axiality on the central Dy^III ion. The effective energy barrier (U_eff) for the loss of magnetization can be varied by the substitution pattern on the dicarbollide. This finding is demonstrated by comparing complexes of nido‐C₂B₉H₁₁^2? and nido‐[o‐xylylene‐C₂B₉H₉]^2?, which show a U_eff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3Dy reaches 6.8 K. Moreover, the linear complex [Dy(C₂B₉H₁₁)₂]^? is predicted to have comparable properties with the linear [Dy(Cp^Me3)₂]⁺ complex. As such, carboranyl ligands and their derivatives may provide a new type of organometallic ligand for high‐performance single‐molecule magnets.     

Mass spectrometric evidence for collisionally induced removal of H2 from monoanions of 10B nido‐carborane derivatives investigated by electrospray ionization quadrupole linear ion trap and Fourier transform ion cyclotron resonance mass spectrometry

Some newly synthesized ¹⁰B nido‐carborane derivatives, i.e., 7,8‐dicarba‐nido‐undecaborane monoanions ([7‐Me‐8‐R‐C₂B₉H₁₀]^‐K⁺, R = H, butyl, hexyl, octyl and decyl), have been fully characterised and examined by electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry with liquid chromatographic separation (LC/ESI‐FTICR‐MS). These boron‐containing compounds exhibit abundant molecular ions ([M]^?) at m/z 140.22631 [CB₉H₁₄]^?, m/z 196.28883 [CB₉H₂₂]^?, m/z 224.32032 [CB₉H₂₆]^?, m/z 252.35133 [CB₉H₃₀]^? and m/z 280.38354 [CB₉H₃₄]^? at the normal tube lens voltage setting of ?90 V, which was an instrumental parameter value selected in the tuning operation. Additional [M–nH₂]^? (n = 1?4) ions were observed in the mass spectra when higher tube lens voltages were applied, i.e., ?140 V. High‐resolution FTICR‐MS data revealed the accurate masses of fragment ions, bearing either an even or an odd number of electrons. Collision‐induced dissociation of the [M–nH₂]^? ions (n = 0–4) in the quadrupole linear ion trap (LTQ) analyzer confirmed the loss of hydrogen molecules from the molecular ions. It is suggested that the loss of H₂ molecules from the alkyl chain is a consequence of the stabilization effect of the nido‐carborane charged polyhedral skeleton. Copyright © 2009 John Wiley & Sons, Ltd.     

Electrophile‐Induced Nucleophilic Substitution of the nido‐Dicarbaundecaborate Anion nido‐7,8‐C2B9H12− by Conjugated Heterodienes

Substitution of the dicarbaundecaborate anion nido‐7,8‐C₂B₉H₁₂^? ( 1 ) by precise hydride abstraction followed by nucleophilic attack usually leads to symmetric products 10‐R‐nido‐7,8‐C₂B₉H₁₁. However, thioacetamide (MeC(S)NH₂) as nucleophile and acetone/AlCl₃ as hydride abstractor gave asymmetric 9‐[MeC(NHiPr)S]‐nido‐7,8‐C₂B₉H₁₁ ( 2 ), whereas N,N‐dimethylthioacetamide (MeC(S)NMe₂) gave the expected symmetric 10‐[MeC(NMe₂)S]‐nido‐7,8‐C₂B₉H₁₁ ( 4 ). For the formation of 2 , acetone and thioacetamide are assumed to give the intermediate MeC(S)N(CMe₂) ( 3 ), which then attacks 1 with formation of 2 . Similarly, reaction of acetyliminium chloride [MeC(O)NH(CPh₂)]Cl ( 5 ) with 1 in THF gave a mixture of 9‐ and 10‐substituted [MeC(NHCHPh₂)O]‐nido‐7,8‐C₂B₉H₁₁ ( 6 and 7 , respectively). These reactions are the first examples in which compounds (here heterodienes) that unite the functionalities of both hydride acceptor and nucleophilic site react with 1 in a bimolecular fashion. Furthermore, the analogous reaction of 1 and 5 (in an equilibrium mixture with acetyl chloride and benzophenone imine) in MeCN afforded 10‐[MeC(NCPh₂)NH]‐nido‐7,8‐C₂B₉H₁₁ ( 8 ) and MeC(O)NHCHPh₂ ( 9 ).     

[Et4N][7‐Me2S‐nido‐B11H12]

Tetraethyl­ammonium 7‐di­methyl­sulfanyl‐nido‐dodeca­hydro­undecaborate, [Et₄N][7‐Me₂S‐nido‐B₁₁H₁₂] or C₈H₂₀N⁺·C₂H₁₈B₁₁S⁻, is a product of the deprotonation of [7‐Me₂S‐nido‐B₁₁H₁₃] with KHBEt₃ and precipitation with tetraethyl­ammonium chloride. The effect of removing one endo‐terminal H atom is to cause a general contraction of the open‐face B—B distances.     

Darstellung und Kristallstrukturen von [P(C6H5)4][1-(NH3)B10H9] und Cs[(NH3)B12H11] · 2CH3OH

Synthesis and Crystal Structures of [P(C₆H₅)₄][1-(NH₃)B₁₀H₉] and Cs[(NH₃)B₁₂H₁₁] · 2CH₃OH The reduction of [1-(NO₂)B₁₀H₉]^2? with aluminum in alkaline solution yields [1-(NH₃)B₁₀H₉]^? and by treatment of [B₁₂H₁₂]^2? with hydroxylamine-O-sulfonic acid [(NH₃)B₁₂H₁₁]^? is formed. The crystal structures of [P(C₆H₅)₄][1-(NH₃)B₁₀H₉] (triclinic, space group P1 , a = 7.491(2), b = 13.341(2), c = 14.235(1) Å, α = 68.127(9), β = 81.85(2), γ = 86.860(3)°, Z = 2) and Cs[(NH₃)B₁₂H₁₁] · 2CH₃OH (monoclinic, space group P2₁/n, a = 14.570(2), b = 7.796(1), c = 15.076(2) Å, β = 111.801(8)°, Z = 4) reveal for both compounds the bonding of an ammine substituent to the cluster anion.     

11‐Vertex arachno‐Clusters with an NB10, SNB9, and SeNB9 Skeleton

One of the two bridging protons of the aza‐nido‐decaboranes RNB₉H₁₀X can be removed by certain bases to give nido‐anions [RNB₉H₉X]^– [R/X = H/H ( 1 a ), Ph/H ( 1 b ), p‐MeC₆H₄/H ( 1 c ), Bzl/H ( 1 d ), H/N₃ ( 1 ′ a )]; the stericly demanding base 1,8‐bis(dimethylamino)naphthalene (“proton sponge”, ps) is ideal. In the case of tBu anion, the deprotonation (→ C₄H₁₀) may be accompanied by a hydridation (→ C₄H₈), yielding the arachno‐anions [RNB₉H₁₁X]^– ( 2 a , b , d , 2 ′ a ); these are the main products, when stericly non‐demanding bases like H^– are applied. The Lewis acid BH₃ is added to 1 a and 1 ′ a to give the aza‐arachno‐undecaborates HNB₁₀H₁₂X [X = H ( 3 a ), N₃ (in position 2) ( 3 ′ a )]. Thia‐ and selenaaza‐arachno‐undecaborates, [S(RN)B₉H₁₀]^– ( 4 b , c ) and [Se(RN)B₉H₁₀]^– ( 4 ′ b , c ), are obtained from 1 b , c by the addition of sulfur or selenium, respectively. The methylation of the anions 4 c and 4 ′ c gives the thia‐ and selenaazaarachno‐undecaboranes (MeS)(RN)B₉H₁₀ ( 5 c ) and (MeSe)(RN)B₉H₁₀ ( 5 ′ c ), respectively. The action of HBF₄ on the arachno‐borates [HNB₁₀H₁₂X]^– ( 3 a , 3 ′ a ) leads to a mixture of nido‐HNB₉H₁₀X and nido‐HNB₁₀H₁₁X by the elimination of BH₃ or H₂, respectively; the aza‐nido‐decaborane predominates in the case of 3 ′ a and the aza‐nido‐undecaborane in the case of 3 a . The action of HBF₄ on the anion 4 c yields the hypho‐undecaborate [S(RN)B₉H₁₀F₂]^– ( 6 c ). The structures of the products are elucidated on the basis of ¹H and ¹¹B NMR spectra, supported by 2D COSY and HMQC techniques. Two types of 11‐vertex‐arachno structures and an 11‐vertex‐hypho structure are found for the products. The crystal structures of 5 c and [Hps] 6 c · CH₂Cl₂ are reported.     

Synthesis and helicity of optically active poly(N‐propargylphosphonamidates) having chiral phosphorus center

Novel chiral N‐propargylphosphonamidate monomers (HC?CCH₂NHP(?O)R? O? menthyl, 1 : R = CH₃, 2 : R = C₂H₅, 3 : R = n‐C₃H₇, 4 : R = Ph) were synthesized by the reaction of the corresponding phosphonic dichlorides with menthol and propargylamine. Pairs of diastereomeric monomers 1 – 4 with different ratios were obtained due to the chiral P‐center and menthyl group. One diastereomer could be separated from another one in the cases of monomers 1 and 2 . Polymerization of 1 – 4 with (nbd)Rh⁺[η⁶‐C₆H₅B^?(C₆H₅)₃] as a catalyst in CHCl₃ gave the polymers with number‐average molecular weights ranging from 5000 to 12,000 in 65–85%. Poly( 1 )–poly( 4 ) exhibited quantitative cis contents, and much larger specific rotations than 1 – 4 did in CHCl₃. The polymers showed an intense Cotton effect around 325 nm based on the conjugated polyacetylene backbone. It was indicated that the polymers took a helical structure with predominantly one‐handed screw sense, and intramolecular hydrogen bonding between P?O and N? H of the polymers contributed to the stability of the helical structure. Poly( 1a ) and poly( 2a ) decreased the CD intensity upon raising CH₃OH content in CHCl₃/CH₃OH. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1515–1524, 2007     

Ten‐vertex rhodadithiaborane ­chemistry: [8‐{I(CH2)5}‐3‐(η5‐C5Me5)‐arachno‐3,7,8‐RhS2B8H9]

Neutral 8‐(5‐iodo‐n‐pentyl)‐3‐(η⁵‐penta­methyl­cyclo­pentadi­enyl)‐arachno‐3‐rhoda‐7,8‐di­thia­undecaborane, [Rh(C₅H₁₉B₈­IS₂)­(C₁₀H₁₅)], obtained from the [arachno‐7,8‐S₂B₉H₁₀]^? anion by treatment with I(CH₂)₅I followed by [Rh(C₅Me₅)Cl₂]₂ and N,N,N′,N′‐tetra­methyl‐1,8‐di­amino­naphthalene, has the 11‐vertex cluster geometry of [arachno‐7,8‐S₂B₉H₁₀]^?, but with an {Rh(C₅Me₅)} unit in the 3‐position instead of a {BH} unit, and with a –(CH₂)₅I chain attached exo to an S atom.     

A Mechanistic Study of the Utilization of arachno‐Diruthenaborane [(Cp*RuCO)2B2H6] as an Active Alkyne‐Cyclotrimerization Catalyst

The reaction of nido‐[1,2‐(Cp*RuH)₂B₃H₇] ( 1 a , Cp*=η⁵‐C₅Me₅) with [Mo(CO)₃(CH₃CN)₃] under mild conditions yields the new metallaborane arachno‐[(Cp*RuCO)₂B₂H₆] ( 2 ). Compound 2 catalyzes the cyclotrimerization of a variety of internal‐ and terminal alkynes to yield mixtures of 1,3,5‐ and 1,2,4‐substituted benzenes. The reactivities of nido‐ 1 a and arachno‐ 2 with alkynes demonstrates that a change in geometry from nido to arachno drives a change in the reaction from alkyne‐insertion to catalytic cyclotrimerization, respectively. Density functional calculations have been used to evaluate the reaction pathways of the cyclotrimerization of alkynes catalyzed by compound 2 . The reaction involves the formation of a ruthenacyclic intermediate and the subsequent alkyne‐insertion step is initiated by a [2+2] cycloaddition between this intermediate and an alkyne. The experimental and quantum‐chemical results also show that the stability of the metallacyclic intermediate is strongly dependent on the nature of the substituents that are present on the alkyne.     

Alternative syntheses and X-ray diffraction analyses of the parent tricarbaborane compounds [nido-7,8,9-C3B8H11], [nido-7,8,10-C3B8H11] and [1-(η-C5H5)-closo-1,2,4,10-FeC3B8H11]

Reaction of the neutral tricarbaborane nido-7,8,9-C₃B₈H₁₂ (1) with triethylamine in CH₂Cl₂ led to quantitative deprotonation and isolation of the corresponding Et₃NH⁺ salt of the [nido-7,8,9-C₃B₈H₁₁]⁻ anion (2). This was converted into PSH⁺ and Me₄N⁺ salts via metathetic cation exchange. Heating of the solid Me₄N⁺[7,8,9-C₃B₈H₁₁]⁻ in mineral oil at 350 °C for 2 h resulted in thermal rearrangement and isolation of the cage isomeric compound Me₄N⁺[7,8,10-C₃B₈H₁₁]⁻. Finally, compound 1 was directly complexed via reaction with [CpFe(CO)₂]₂ (Cp = η⁵-C₅H₅) to generate the ferratricarbollide sandwich [1-Cp-closo-1,2,4,10-FeC₃B₈H₁₁] (4) in 60% yield. The structures of all the generic compounds of tricarbollide chemistry, 1 (PSH⁺ salt), 2 (MePPh₃⁺salt), and 4, were established unambiguously by an X-ray diffraction analysis.     

1‐Oxa‐nido‐dodecaborate [OB11H12]− from the Controlled Oxidation of the closo‐Borates [B11H11]2− and [B12H12]2−

The closo‐dodecaborate [B₁₂H₁₂]^2? is degraded at room temperature by oxygen in an acidic aqueous solution in the course of several weeks to give B(OH)₃. The degradation is induced by Ag²⁺ ions, generated from Ag⁺ by the action of H₂S₂O₈. Oxa‐nido‐dodecaborate(1?) is an intermediate anion, that can be separated from the reaction mixture as [NBzlEt₃][OB₁₁H₁₂] after five days in a yield of 18 %. The action of FeCl₃ on the closo‐undecaborate [B₁₁H₁₁]^2? in an aqueous solution gives either [B₂₂H₂₂]^2? (by fusion) or nido‐B₁₁H₁₃(OH)^? (by protonation and hydration), depending on the concentration of FeCl₃. In acetonitrile, however, [B₁₁H₁₁]^2? is transformed into [OB₁₁H₁₂]^? by Fe³⁺ and oxygen. The radical anions [B₁₂H₁₂] ^{˙ ?} and [B₁₁H₁₁] ^{˙ ?} are assumed to be the primary products of the oxidation with the one‐electron oxidants Ag²⁺ and Fe³⁺, respectively. These radical anions are subsequently transformed into [OB₁₁H₁₂]^? by oxygen. The crystal structure analysis shows that the structure of [OB₁₁H₁₂]^? is derived from the hypothetical closo‐oxaborane OB₁₂H₁₂ by removal of the B3 vertex, leaving a non‐planar pentagonal aperture with a three‐coordinate O vertex, as predicted by NMR spectra and theory.     

Structure and formation of gaseous [C4H6O]+˙ ions: 1—The enolic ions [CH2C(OH)?CHCH2]+˙ and [CH2CH?CHCH(OH)]+˙ and their relationship with their keto counterparts

The [C₄H₆O]^+˙ ion of structure [CH₂?CHCH?CHOH]^+˙ (a) is generated by loss of C₄H₈ from ionized 6,6-dimethyl-2-cyclohexen-1-ol. The heat of formation ΔH_f of [CH₂?CHCH?CHOH]^+˙ was estimated to be 736 kJ mol^?1. The isomeric ion [CH₂?C(OH)CH?CH₂]^+˙ (b) was shown to have ΔH_f, ? 761 kJ mol^?1, 54 kJ mol^?1 less than that of its keto analogue [CH₃COCH?CH₂]^+˙. Ion [CH₂?C(OH)CH?CH₂]^+˙ may be generated by loss of C₂H₄ from ionized hex-1-en-3-one or by loss of C₄H₈ from ionized 4,4-dimethyl-2-cyclohexen-1-ol. The [C₄H₆O]^+˙ ion generated by loss of C₂H₄ from ionized 2-cyclohexen-1-ol was shown to consist of a mixture of the above enol ions by comparing the metastable ion and collisional activation mass spectra of [CH₂?CHCH?CHOH]^+˙ and [CH₂?C(OH)CH?CH₂]^+˙ ions with that of the above daughter ion. It is further concluded that prior to their major fragmentations by loss of CH₃˙ and CO, [CH₂?CHCH?CHOH]⁺˙ and [CH₂?C(OH)CH?CH₂]^+˙ do not rearrange to their keto counterparts. The metastable ion and collisional activation characteristics of the isomeric allenic [C₄H₆O]^+˙ ion [CH₂?C?CHCH₂OH]^+˙ are also reported.     

Synthesis and crystal structure of three nido 11‐vertex platinaborane clusters

The reaction of [PtCl₂(PPh₃)₂] with closo‐B₁₀H₁₀^2? in ethanol under reflux conditions gave two nido 11‐vertex platinaundecaborane clusters: [(PPh₃)₂PtB₁₀H₁₀‐8,10‐(OEt)₂]·CH₂Cl₂ (1) and [(PPh₃)₂PtB₁₀H₁₁‐11‐OEt]·CH₂Cl₂ (2) . A novel B₁₀H₁₀^2? deboronated nido 11‐vertex diplatinaundecaborane [(µ‐PPh₂)(PPh₃)₂Pt₂B₉H₆‐3,9,11‐(OEt)₃]·CH₂Cl₂ (3) was obtained when the same reaction was carried out under solvothermal conditions. All of these compounds were characterized by infrared spectroscopy, NMR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. Both clusters 1 and 2 have a nido 11‐vertex {PtB₁₀} polyhedral skeleton in which the Pt atom lies in the open PtB₄ face. Each Pt atom connects with four B atoms and two P atoms of the PPh₃ ligands. Cluster 3 has a nido 11‐vertex {Pt₂B₉} polyhedral skeleton in which two Pt atoms sit in neighbouring positions of the open Pt₂B₃ face, bridged by a PPh₂ group. Each Pt atom connects three B atoms and a P atom of the PPh₃ ligand. Copyright © 2005 John Wiley & Sons, Ltd.     

Selenoquinones Stabilized by Ruthenium(II) Arene Complexes: Synthesis,Structure, and Cytotoxicity

A new series of monoselenoquinone and diselenoquinone π complexes, [(η⁶‐p‐cymene)Ru(η⁴‐C₆R₄SeE)] (R=H, E=Se ( 6 ); R=CH₃, E=Se ( 7 ); R=H, E=O ( 8 )), as well as selenolate π complexes [(η⁶‐p‐cymene)Ru(η⁵‐C₆H₃R₂Se)][SbF₆] (R=H ( 9 ); R=CH₃ ( 10 )), stabilized by arene ruthenium moieties were prepared in good yields through nucleophilic substitution reactions from dichlorinated‐arene and hydroxymonochlorinated‐arene ruthenium complexes [(η⁶‐p‐cymene)Ru(C₆R₄XCl)][SbF₆]₂ (R=H, X=Cl ( 1 ); R=CH₃, X=Cl ( 2 ); R=H, X=OH ( 3 )) as well as the monochlorinated π complexes [(η⁶‐p‐cymene)Ru(η⁵‐C₆H₃R₂Cl)][SbF₆]₂ (R=H ( 4 ); R=CH₃ ( 5 )). The X‐ray crystallographic structures of two of the compounds, [(η⁶‐p‐cymene)Ru(η⁴‐C₆Me₄Se₂)] ( 7 ) and [(η⁶‐p‐cymene)Ru(η⁴‐C₆H₄SeO)] ( 8 ), were determined. The structures confirm the identity of the target compounds and ascertain the coordination mode of these unprecedented ruthenium π complexes of selenoquinones. Furthermore, these new compounds display relevant cytotoxic properties towards human ovarian cancer cells.     

Dysprosiacarboranes as Organometallic Single-Molecule Magnets

The dicarbollide ion, nido-C₂B₉H₁₁²⁻ is isoelectronic with cyclopentadienyl. Herein, we make dysprosiacarboranes, namely [(C₂B₉H₁₁)₂Ln(THF)₂][Na(THF)₅] (Ln=Dy, 1Dy ) and [(THF)₃(μ-H)₃Li]₂[{η⁵-C₆H₄(CH₂)₂C₂B₉H₉}Dy{η²:η⁵-C₆H₄(CH₂)₂C₂B₉H₉}₂Li] 3Dy and show that dicarbollide ligands impose strong magnetic axiality on the central Dy^III ion. The effective energy barrier (U_eff) for the loss of magnetization can be varied by the substitution pattern on the dicarbollide. This finding is demonstrated by comparing complexes of nido-C₂B₉H₁₁²⁻ and nido-[o-xylylene-C₂B₉H₉]²⁻, which show a U_eff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3Dy reaches 6.8 K. Moreover, the linear complex [Dy(C₂B₉H₁₁)₂]⁻ is predicted to have comparable properties with the linear [Dy(Cp^Me3)₂]⁺ complex. As such, carboranyl ligands and their derivatives may provide a new type of organometallic ligand for high-performance single-molecule magnets.     

Synthesis reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (III) complexes

Cyclopentadienyl cobalt complexes (η⁵‐C₅H₄R) CoLI₂ [L = CO,R=‐COOCH₂CH=CH₂ (3); L=PPh₃, R=‐COOCH₂‐CH=CH₂ (6); L=P(p‐C₆H₄O₃)₃, R = ‐COOC(CH₃) = CH₂ (7), ‐COOCH₂C₆H₅ (8), ‐COOCH₂CH = CH₂ (9)] were prepared and characterized by elemental analyses, ¹H NMR, ER and UV‐vis spectra. The reaction of complexes (η⁵‐C₅H₄R)CoLI₂ [L= CO, R= ‐COOC(CH₃) = CH₂ (1), ‐COOCH₂C₆H₅(2); L=PPh₃, R=‐COOC (CH₃) = CH₂ (4), ‐COOCH₂C₆H₅ (5)] with Na‐Hg resulted in the formation of their corresponding substituted cobaltocene (η⁵‐C₅H₄R)₂ Co[R=‐COOC(CH₃) = CH₂ (10), ‐COOCH₂C₆H₅ (11)]. The electrochemical properties of these complexes 1–11 were studied by cyclic voltammetry. It was found that as the ligand (L) of the cobalt (III) complexes changing from CO to PPh₃ and P(p‐tolyl)₃, their oxidation potentials increased gradually. The cyclic voltammetry of α,α′‐substituted cobaltocene showed reversible oxidation of one electron process.     

An Organically Templated Copper Pentaborate with Infinite Metallo-chains:[Cu(C3N2H4)4][Cu(CH3COO)2(C3N2H4)2(H2O)2][B5O6(OH)4]2

A novel organically templated copper pentaborate, [Cu(C₃N₂H₄)₄][Cu(CH₃COO)₂(C₃N₂H₄)₂(H₂O)₂]‐ [B₅O₆(OH)₄]₂, was synthesized by hydrothermal reaction and characterized by elemental analysis, single‐crystal X‐ray diffraction, FT‐IR spectroscopy, Raman spectroscopy and TGA. The crystal structure of this compound consists of two copper‐centered polyhedra and two discrete [B₅O₆(OH)₄]^? pentaborate anions, which are linked together through intensive hydrogen bonding interactions, forming a 3D framework with large channels along c axis. The discrete pentaborate anions form infinite layers by hydrogen bonds. Moreover, the two crystallographically different octahedral coppers are connected by common oxygen atom to form an infinite chain.