Gadolinium-based mixed-metal nitride clusterfullerenes Gd(x)Sc(3-x)N@C80 (x=1, 2).

The first gadolinium-based mixed-metal nitride clusterfullerenes Gd(x)Sc(3-x)N@C(80) (I) (1, x=2; 2, x=1) have been successfully synthesized by the reactive gas atmosphere method and isolated facilely by recycling high-performance liquid chromatography (HPLC). The sum yield of 1 and 2 is 30-40 times higher than that of Gd(3)N@C(80) (I). Moreover, an enhanced relative yield of 2 over the Sc(3)N@C(80) (I) is achieved under the optimized synthesis conditions. According to the UV/Vis/NIR spectroscopic characterization, 1 and 2 are both stable fullerenes with large optical band-gaps while 1 has higher similarity to Gd(3)N@C(80) (I) and 2 resembles Sc(3)N@C(80) (I). The vibrational structures of 1 and 2 are studied by Fourier-transform infrared (FTIR) spectroscopy as well as density functional theory (DFT) computations. In particular, the structures of the encaged Gd(x)Sc(3-x)N clusters within 1 and 2 are analyzed.     

Synthesis,Isolation, and Spectroscopic Characterization of Holmium‐Based Mixed‐Metal Nitride Clusterfullerenes: HoxSc3−xN@C80 (x=1, 2)

The synthesis, isolation and spectroscopic characterization of holmium‐based mixed metal nitride clusterfullerenes Ho_xSc_3?xN@C₈₀ (x=1, 2) are reported. Two isomers of Ho_xSc_3?xN@C₈₀ (x=1, 2) were synthesized by the reactive gas atmosphere method and isolated by multistep recycling HPLC. The isomeric structures of Ho_xSc_3?xN@C₈₀ (x=1, 2) were characterized by laser‐desorption time‐of‐flight (LD‐TOF) mass spectrometry and UV/Vis/NIR, FTIR and Raman spectroscopy. A comparative study of M_xSc_3?xN@C₈₀ (M=Gd, Dy, Lu, Ho) demonstrates the dependence of their electronic and vibrational properties on the encaged metal. Despite the distinct perturbation induced by 4f¹⁰ electrons, we report the first paramagnetic ¹³C NMR study on Ho_xSc_3?xN@C₈₀ (I; x=1, 2) and confirm I_h‐symmetric cage structure. A ⁴⁵Sc NMR study on HoSc₂N@C₈₀ (I, II) revealed a temperature‐dependent chemical shift in the temperature range of 268–308 K.     

Synthesis, isolation, and spectroscopic characterization of holmium-based mixed-metal nitride clusterfullerenes: HoxSc3-xN@C80 (x=1, 2)

The synthesis, isolation and spectroscopic characterization of holmium-based mixed metal nitride clusterfullerenes Ho(x) Sc(3-x) N@C(80) (x=1, 2) are reported. Two isomers of Ho(x) Sc(3-x) N@C(80) (x=1, 2) were synthesized by the reactive gas atmosphere method and isolated by multistep recycling HPLC. The isomeric structures of Ho(x) Sc(3-x) N@C(80) (x=1, 2) were characterized by laser-desorption time-of-flight (LD-TOF) mass spectrometry and UV/Vis/NIR, FTIR and Raman spectroscopy. A comparative study of M(x) Sc(3-x) N@C(80) (M=Gd, Dy, Lu, Ho) demonstrates the dependence of their electronic and vibrational properties on the encaged metal. Despite the distinct perturbation induced by 4f(10) electrons, we report the first paramagnetic (13) C?NMR study on Ho(x) Sc(3-x) N@C(80) (I; x=1, 2) and confirm I(h) -symmetric cage structure. A (45) Sc NMR study on HoSc(2) N@C(80) (I, II) revealed a temperature-dependent chemical shift in the temperature range of 268-308?K.     

Two Regioisomers of Endohedral Pyrrolidinodimetallofullerenes M2@Ih‐C80(CH2)2NTrt (M=La,Ce; Trt=trityl): Control of Metal Atom Positions by Addition Positions

The two regioisomers of endohedral pyrrolidinodimetallofullerenes M₂@I_h‐C₈₀(CH₂)₂NTrt (M=La, Ce; Trt=trityl) were synthesized, isolated, and characterized. X‐ray crystallographic analyses of [6,6]‐La₂@I_h‐C₈₀(CH₂)₂NTrt and [6,6]‐Ce₂@I_h‐C₈₀(CH₂)₂NTrt revealed that the encapsulated metal atoms are located at the slantwise positions on the mirror plane that parallels the pyrrolidine ring. Paramagnetic NMR analyses of [6,6]‐ and [5,6]‐Ce₂@I_h‐C₈₀(CH₂)₂NTrt were also carried out to clarify the metal positions. As for the [6,6]‐adduct, the metal positions obtained by paramagnetic NMR analysis agree well with the X‐ray structure. In contrast, paramagnetic NMR analysis of the [5,6]‐adduct showed that the two Ce atoms are collinear with the pyrrolidine ring. We also compared the observed paramagnetic effects of the pyrrolidinodimetallofullerenes with those of other cerium‐encapsulating fullerene derivatives such as bis‐silylated Ce₂@I_h‐C₈₀ and a carbene adduct of Ce₂@I_h‐C₈₀. We found that the metal positions can be explained by the electrostatic potential maps of the corresponding [6,6]‐ and [5,6]‐adducts of [I_h‐C₈₀(CH₂)₂NTrt]^6?. These findings clearly show that metal positions inside fullerene cages can be controlled by means of the addition positions of the addends. In addition, the radical anions of the pyrrolidinodimetallofullerenes were prepared by bulk controlled‐potential electrolysis and characterized by X‐band EPR spectral study.     

Vibrational structure of endohedral fullerene Sc3N@C78 (D3h'): evidence for a strong coupling between the Sc3N cluster and C78 cage.

The vibrational structure of the endohedral cluster fullerene Sc(3)N@C(78) is studied by FTIR spectroscopy, Raman spectroscopy and DFT-based quantum chemical calculations. Remarkably good agreement between experimental and calculated spectra is achieved and a full assignment of the Sc(3)N-based vibrational modes is given. Significant differences in the vibrational structure of the endohedral cluster fullerene Sc(3)N@C(78) and the empty, charged C(78) (6-): 5 (D(3h)') are rationalized by the strong coupling between the Sc(3)N cluster and the fullerene cage. This coupling has its origin in a significant overlap of the Sc(3)N and C(78) molecular orbitals, and causes atomic-charge and bond-length redistributions compared to the neutral C(78) and the C(78) (6-) anion. An ionic model is not sufficient to describe the electronic, geometric and vibrational structure of the Sc(3)N@C(78) nitride cluster fullerene.     

Charge-induced reversible rearrangement of endohedral fullerenes: electrochemistry of tridysprosium nitride clusterfullerenes Dy3N@C2n (2n=78, 80)

The electrochemistry of three new clusterfullerenes Dy3N@C2n (2n=78, 80), namely two isomers of Dy3N@C80 (I and II) as well as Dy3N@C78 (II), have been studied systematically including their redox-reaction mechanism. The cyclic voltammogram of Dy3N@C80 (I) (Ih) exhibits two electrochemically irreversible but chemically reversible reduction steps and one reversible oxidation step. Such a redox pattern is quite different from that of Sc3N@C80 (I), and this can be understood by considering the difference in the charge transfer from the encaged cluster to the cage. A double-square reaction scheme is proposed to explain the observed redox-reaction behavior, which involves the charge-induced reversible rearrangement of the Dy3N@C80 (I) monoanion. The first oxidation potential of Dy3N@C80 (II) (D5h) has a negative shift of 290 mV relative to that of Dy3N@C80 (I) (Ih), indicating that lowering the molecular symmetry of the clusterfullerene cage results in a prominent increase in the electron-donating property. The first and second reduction potentials of Dy3N@C78 (II) are negatively shifted relative to those of Dy3N@C80 (I, II), pointing to the former's lowered electron-accepting ability. The significant difference in the electrochemical energy gaps of Dy3N@C80 (I), Dy3N@C80 (II), and Dy3N@C78 (II) is consistent with the difference in their optical energy gaps.     

Die Reaktionen von M[BF4] (M = Li,K) und (C2H5)2O·BF3 mit (CH3)3SiCN. Bildung von M[BFx>(CN)4—x] (M = Li,K; x = 1, 2) und (CH3)3SiNCBFx(CN)3—x, (x = 0, 1)

The Reactions of M[BF₄] (M = Li, K) and (C₂H₅)₂O·BF₃ with (CH₃)₃SiCN. Formation of M[BF_x(CN)_4—x] (M = Li, K; x = 1, 2) and (CH₃)₃SiNCBF_x(CN)_3—x, (x = 0, 1) The reaction of M[BF₄] (M = Li, K) with (CH₃)₃SiCN leads selectively, depending on the reaction time and temperature, to the mixed cyanofluoroborates M[BF_x(CN)_4—x] (x = 1, 2; M = Li, K). By using (C₂H₅)₂O·BF₃ the synthesis yields the compounds (CH₃)₃SiNCBF_x(CN)_3—x x = 0, 1. The products are characterized by vibrational and NMR‐spectroscopy, as well as by X‐ray diffraction of single‐crystals: Li[BF₂(CN)₂]·2Me₃SiCN Cmc2₁, a = 24.0851(5), b = 12.8829(3), c = 18.9139(5) Å V = 5868.7(2) ų, Z = 12, R₁ = 4.7%; K[BF₂(CN)₂] P4₁2₁2, a = 13.1596(3), c = 38.4183(8) Å, V = 6653.1(3) ų, Z = 48, R₁ = 2.5%; K[BF(CN)₃] P1¯, a = 6.519(1), b = 7.319(1), c = 7.633(2) Å, α = 68.02(3), β = 74.70(3), γ = 89.09(3)°, V = 324.3(1) ų, Z = 2, R₁ = 3.6%; Me₃SiNCBF(CN)₂ Pbca, a = 9.1838(6), b = 13.3094(8), c = 16.840(1) Å, V = 2058.4(2) ų, Z = 8, R₁ = 4.4%     

Synthesis and structural analysis of the polymetallated alkali calixarenes [M4(p-tert-butylcalix[4]arene-4H)(thf)x]2.n THF (M=Li,K; n=6 or 1; x=4 or 5) and [Li2(p-tert-butylcalix[4]arene-2H)(H2O)(mu-H2O)(thf)].3 THF

To study the structures and reactivities of alkali metallated intermediates of calix[4]arenes, three compounds were isolated: [Li(4)(p-tert-butylcalix[4]arene-4H)(thf)(4)](2).6 THF (1), [Li(2)(p-tert-butylcalix[4]arene-2H)(H(2)O)(mu-H(2)O)(thf)].3 THF (2), and [K(4)(p-tert-butylcalix[4]arene-4H)(thf)(5)](2).THF (3). The structure of 1 is shown to be dependent on the coordinating solvent. Partial hydrolysis of 1 leads to the formation of 2. The potassium compound 3 features a different structure to that of 1, due to a higher coordination number as well as stronger cation-pi-bonding interactions.     

Formation and chemical reactivities of a new type of double-butterfly [[Fe2(mu-CO)(CO)6]2(mu-SZS-mu)]2-: synthetic and structural studies on novel linear and macrocyclic butterfly Fe/E (E=S,Se) cluster complexes

A new type of double-butterfly [[Fe(2)(mu-CO)(CO)(6)](2)(mu-SZS-mu)](2-) (3), a dianion that has two mu-CO ligands, has been synthesized from dithiol HSZSH (Z=(CH(2))(4), CH(2)(CH(2)OCH(2))(1-3)CH(2)), [Fe(3)(CO)(12)], and Et(3)N in a molar ratio of 1:2:2 at room temperature. Interestingly, the in situ reactions of dianions 3 with various electrophiles affords a series of novel linear and macrocyclic butterfly Fe/E (E=S, Se) cluster complexes. For instance, while reactions of 3 with PhC(O)Cl and Ph(2)PCl give linear clusters [[Fe(2)(mu-PhCO)(CO)(6)](2)(mu-SZS-mu)] (4 a,b: Z=CH(2)(CH(2)OCH(2))(2,3)CH(2)) and [[Fe(2)(mu-Ph(2)P)(CO)(6)](2)(mu-SZS-mu)] (5 a,b: Z=CH(2)(CH(2)OCH(2))(2,3)CH(2)), reactions with CS(2) followed by treatment with monohalides RX or dihalides X-Y-X give both linear clusters [[Fe(2)(mu-RCS(2))(CO)(6)](2)(mu-SZS-mu)] (6 a-e: Z=CH(2)(CH(2)OCH(2))(1,2)CH(2); R=Me, PhCH(2), FeCp(CO)(2)) and macrocyclic clusters [[Fe(2)(CO)(6)](2)(mu-SZS-mu)(mu-CS(2)YCS(2)-mu)] (7 a-e: Z=(CH(2))(4), CH(2)(CH(2)OCH(2))(1-3)CH(2); Y=(CH(2))(2-4), 1,3,5-Me(CH(2))(2)C(6)H(3), 1,4-(CH(2))(2)C(6)H(4)). In addition, reactions of dianions 3 with [Fe(2)(mu-S(2))(CO)(6)] followed by treatment with RX or X-Y-X give linear clusters [[[Fe(2)(CO)(6)](2)(mu-RS)(mu(4)-S)](2)(mu-SZS-mu)] (8 a-c: Z=CH(2)(CH(2)OCH(2))(1,2)CH(2); R=Me, PhCH(2)) and macrocyclic clusters [[[Fe(2)(CO)(6)](2)(mu(4)-S)](2)(mu-SYS-mu)(mu-SZS-mu)] (9 a,b: Z=CH(2)(CH(2)OCH(2))(2,3)CH(2); Y=(CH(2))(4)), and reactions with SeCl(2) afford macrocycles [[Fe(2)(CO)(6)](2)(mu(4)-Se)(mu-SZS-mu)] (10 d: Z=CH(2)(CH(2)OCH(2))(3)CH(2)) and [[[Fe(2)(CO)(6)](2)(mu(4)-Se)](2)(mu-SZS-mu)(2)] (11 a-d: Z=(CH(2))(4), CH(2)(CH(2)OCH(2))(1-3)CH(2)). Production pathways have been suggested; these involve initial nucleophilic attacks by the Fe-centered dianions 3 at the corresponding electrophiles. All the products are new and have been characterized by combustion analysis and spectroscopy, and by X-ray diffraction techniques for 6 c, 7 d, 9 b, 10 d, and 11 c in particular. X-ray diffraction analyses revealed that the double-butterfly cluster core Fe(4)S(2)Se in 10 d is severely distorted in comparison to that in 11 c. In view of the Z chains in 10 a-c being shorter than the chain in 10 d, the double cluster core Fe(4)S(2)Se in 10 a-c would be expected to be even more severely distorted, a possible reason for why 10 a-c could not be formed.     

Rare-earth tricyanomelaminates [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)H(2)O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): structural investigation, solid-state NMR spectroscopy, and photoluminescence

The rare-earth tricyanomelaminates, [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O (LnTCM; Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy), have been synthesized through ion-exchange reactions. They have been characterized by powder as well as single-crystal X-ray diffraction analysis, vibrational spectroscopy, and solid-state (1)H, (13)C, and (15)N MAS NMR spectroscopy. The X-ray powder pattern common to all nine rare-earth tricyanomelaminates LnTCM (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) indicates that they are isostructural. The single-crystal X-ray diffraction pattern of LnTCM is indicative of non-merohedral twinning. The crystals are triclinic and separation of the twin domains as well as refinement of the structure were successfully carried out in the space group P1 for LaTCM (LaTCM; P1, Z=2, a=7.1014(14), b=13.194(3), c=13.803(3) A, alpha=90.11(3), beta=77.85(3), gamma=87.23(3) degrees , V=1262.8(4) A(3)). In the crystal structure, each Ln(3+) is surrounded by two nitrogen atoms from two crystallographically independent tricyanomelaminate moieties and seven oxygen atoms from crystal water molecules. The positions of all of the hydrogen atoms of the ammonium ions and water molecules could not be located from difference Fourier syntheses. The presence of [NH(4)](+) ions as well as two NH groups belonging to two crystallographically independent monoprotonated tricyanomelaminate moieties has only been confirmed by subjecting LaTCM to solid-state (1)H, (13)C, and (15)N{(1)H} cross-polarization (CP) MAS NMR and advanced CP experiments such as cross-polarization combined with polarization inversion (CPPI). The (1)H 2D double-quantum single-quantum homonuclear correlation (DQ SQ) spectrum and the (15)N{(1)H} 2D CP heteronuclear-correlation (HETCOR) spectrum have revealed the hydrogen-bonded (N--HN) dimer of monoprotonated tricyanomelaminate moieties as well as H-bonding through [NH(4)](+) ions and H(2)O molecules. The structures of the other eight rare-earth tricyanomelaminates (LnTCM; Ln=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) have been refined from X-ray powder diffraction data by the Rietveld method. Photoluminescence studies of [NH(4)]Eu[HC(6)N(9)](2)[H(2)O](7)xH(2)O have revealed orange-red (lambda(max)=615 nm) emission due to the (5)D(0)-(7)F(2) transition, whereas [NH(4)]Tb[HC(6)N(9)](2)[H(2)O](7)xH(2)O has been found to show green emission with a maximum at 545 nm arising from the (5)D(4)-(7)F(5) transition. DTA/TG studies of [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O have indicated several phase transitions associated with dehydration of the compounds above 150 degrees C and decomposition above 200 degrees C.     

Synthesis, molecular structure and properties of the [H6-nNi30C4(CO)34(CdCl)2]n- (n=3-6) bimetallic carbide carbonyl cluster: a model for the growth of noncompact interstitial metal carbides

Reaction of the [Ni(9)C(CO)(17)](2-) dianion with CdCl(2)2.5 H(2)O in THF affords the novel bimetallic Ni--Cd carbide carbonyl clusters [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-) (n=3-6), which undergo several protonation-deprotonation equilibria in solution depending on the basicity of the solvent or upon addition of acids or bases. Although the occurrence in solution of these equilibria complicates the pertinent electrochemical studies on their electron-transfer activity, they clearly indicate that the clusters [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-) (n=3-6), as well as the structurally related [H(6-n)Ni(34)C(4)(CO)(38)](n-) (n=4-6), undergo reversible or partially reversible redox processes and provide circumstantial and unambiguous evidence for the presence of hydrides for n=3, 4 and 5. Three of the [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-) anions (n=4-6) have been structurally characterized in their [NMe(3)(CH(2)Ph)](4)[H(2)Ni(30)C(4)(CO)(34)(CdCl)(2)]2 COMe(2), [NEt(4)](5)[HNi(30)C(4)(CO)(34)(CdCl)(2)]2 MeCN and [NMe(4)](6)[Ni(30)C(4)(CO)(34)(CdCl)(2)]6 MeCN salts, respectively. All three anions display almost identical geometries and bonding parameters, probably because charge effects are minimized by delocalization over such a large metal carbonyl anion. Moreover, the Ni(30)C(4) core in these Ni-Cd carbide clusters is identical within experimental error to those present in the [HNi(34)C(4)(CO)(38)](5-) and [Ni(35)C(4)(CO)(39)](6-) species, suggesting that the stepwise assembly of their nickel carbide cores may represent a general pathway of growth of nickel polycarbide clusters. The fact that the [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-)(n=4-6) anions display two valence electrons more than the structurally related [H(6-n)Ni(34)C(4)(CO)(38)](n-) (n=4-6) species has been rationalized by extended Hückel molecular orbital (EHMO) analysis.     

Syntheses and Characterization of (C2F5)3BCO and (C3F7)3BCO

The new tris(perfluoroalkyl)borane carbonyls, (C₂F₅)₃BCO and (C₃F₇)₃BCO, were prepared by means of a novel synthetic route using commercially available precursors by reacting K[(C₂F₅)₃BCOOH] and K[(C₃F₇)₃BCOOH] with concentrated sulfuric acid in the last step. The carboxylic acids, K[(C₂F₅)₃BCOOH] and K[(C₃F₇)₃BCOOH], were prepared by oxidative cleavage of the C?C triple bonds in Cs[(C₂F₅)₃BC?CPh] and Cs[(C₃F₇)₃BC?CPh] in a two‐step process to yield K[(C₂F₅)₃BCO? COPh] and K[(C₃F₇)₃BCO? COPh] as isolable intermediates. Crystal structures were obtained of K[(C₂F₅)₃BCO? COPh], K[(C₂F₅)₃BCOOH] ? H₂O, (C₂F₅)₃BCO, K[(C₃F₇)₃BCOOH] ? 2 H₂O, and (C₃F₇)₃BCO. In the crystal structures of (C₂F₅)₃BCO and (C₃F₇)₃BCO the C?O bond lengths are 1.109(2) and 1.103(5) Å, respectively, which are among the shortest observed to date. Tris(pentafluoroethyl)borane carbonyl and (C₃F₇)₃BCO slowly decompose at room temperature to yield CO, difluoroperfluoroalkylboranes and perfluoroalkenes. The decomposition of (C₂F₅)₃BCO was found to follow a first‐order rate law with E_a=107 kJ mol^?1.     

A facile route to the non-IPR fullerene Sc3N@C68: synthesis, spectroscopic characterization, and density functional theory computations (IPR=isolated pentagon rule)

Owing to the unique feature of the non-IPR D3 (isomer 6140) C68 cage (IPR=isolated pentagon rule), Sc3N@C68 has been attracting great interest in the fullerene community. Herein we report the first high-yield synthesis of Sc3N@C68 by the "reactive gas atmosphere" method and its facile isolation by single-step HPLC to a high purity (>or=99 %). Thus, Sc3N@C68 is isolated in sufficient quantities for its further spectroscopic characterization, while the high purity of the sample ensures the reliability of the spectroscopic data obtained. In particular, the electronic and vibrational structures of Sc3N@C68 were studied in detail experimentally and by theoretical computations. The assignment of the observed absorption bands to particular electronic transitions is given in detail on the basis of time-dependent DFT computations. Vibrational spectroscopy of Sc3N@C68 reveals good agreement between the measured spectra and the theoretically calculated spectra. A detailed assignment of the vibrational modes, including the Sc3N cluster modes, cage modes, and vibrations of the adjacent pentagons are discussed. This study reveals that the effect of Sc3N encapsulation in the cage is much more complicated than just a formal transfer of six electrons. Consequently the electronic and vibrational spectra of the carbon cage in Sc3N@C68 cannot be adequately understood on the basis of a C68 (6-) cage alone.     

The Vanadium(V) Oxoazides [VO(N3)3], [(bipy)VO(N3)3], and [VO(N3)5]2−

Vanadium(V) oxoazide [VO(N₃)₃] was prepared through a fluoride–azide exchange reaction between [VOF₃] and Me₃SiN₃ in acetonitrile solution. When the highly impact‐ and friction‐sensitive compound [VO(N₃)₃] was reacted with 2,2′‐bipyridine, the adduct [(bipy)VO(N₃)₃] was isolated. The reaction of [VO(N₃)₃] with [PPh₄]N₃ resulted in the formation and isolation of the salt [PPh₄]₂[VO(N₃)₅]. The adduct [(bipy)VO(N₃)₃] and the salt [PPh₄]₂₃[VO(N₃)₅] were characterized by vibrational spectroscopy and single‐crystal X‐ray structure determination, making these compounds the first structurally characterized vanadium(V) azides.