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James C Fettinger

Publications and source records attributed to James C Fettinger.

At least 19 recordsLinked to original sources

Synthesis, structural characterization, and spectroscopy of the cadmium-cadmium bonded molecular species Ar'CdCdAr' (Ar' = C6H3-2,6-(C6H3-2,6-Pri2)2).

The synthesis and first structural characterization of a cadmium-cadmium bonded molecular compound Ar'CdCdAr' (Ar' = C6H3-2,6-(C6H3-2,6-Pri2)2) are reported. The existence of the Cd-Cd bond was established by 113Cd NMR spectroscopy and X-ray diffraction (Cd-Cd = 2.6257(5) A). Like its group 12 analogue Ar'ZnZnAr', DFT calculations showed that Ar'CdCdAr' had significant p-character in the Cd-Cd sigma-bonding HOMO.

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Quasi-isomeric gallium amides and imides GaNR2 and RGaNR (R = organic group): reactions of the digallene, Ar'GaGaAr' (Ar' = C6H3-2,6-(C6H3-2,6-Pri2)2) with unsaturated nitrogen compounds.

Reactions of the "digallene" Ar'GaGaAr'(1) (Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-Pr(i)(2))(2)), which dissociates to green :GaAr' monomers in solution, with unsaturated N-N-bonded molecules are described. Treatment of solutions of :GaAr' with the bulky azide N(3)Ar(#) (Ar(#) = C(6)H(3)-2,6-(C(6)H(2)-2,6-Me(2)-4-Bu(t))(2)), afforded the red imide Ar'GaNAr(#) (2). Addition of the azobenzenes, ArylNNAryl (Aryl = C(6)H(4)-4-Me (p-tolyl), mesityl, and C(6)H(3)-2,6-Et(2)) yielded the 1,2-Ga(2)N(2) ring compound Ar'GaN(p-tolyl)N(p-tolyl)GaA' (3) or the products MesN=NC(6)H(2)-2,4-Me(2)-6-Ga(Me)Ar' (4) and 2,6-Et(2)C(6)H(3)N=NC(6)H(3)-2-Et-6-Ga(Et)Ar' (5). Reaction of GaAr' with N(2)CPh(2) yielded the 1,3-Ga(2)N(2) ring compound Ar'Ga(mu:eta(1)-N(2)CPh(2))(2)GaAr' (6), which is quasi-isomeric to 3. Calculations on simple model isomers showed that the Ga(I) amide GaNR(2) (R = Me) is much more stable than the isomeric Ga(III) imide RGaNR. This led to the synthesis of the first stable monomeric Ga(I) amide, GaN(SiMe(3))Ar' ' (8) (Ar' ' = C(6)H(3)-2,6-(C(6)H(2)-2,4,6-Me(3))(2) from the reaction of LiN(SiMe(3))Ar' ' (7) and "GaI". Compound 8 is also the first one-coordinate gallium species to be characterized in the solid state. The reaction of 8 with N(3)Ar' ' afforded the amido-imide derivative Ar' 'NGaN(SiMe(3))Ar' ' (9), a gallium nitrogen analogue of an allyl anion. All compounds were spectroscopically and structurally characterized. In addition, DFT calculations were performed on model compounds of the amide, imide, and cyclic 1,2- and 1,3-species to better understand their bonding. The pairs of compounds 2 and 8 as well as 3 and 6 are rare examples of quasi-isomeric heavier main group element compounds.

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Very large changes in bond length and bond angle in a heavy group 14 element alkyne analogue by modification of a remote ligand substituent.

The synthesis and characterization of the compound Me3Si-4-Ar'SnSnAr'-4-SiMe3 (Ar'-4-SiMe3 = C6H2-2,6-(C6H3-2,6-i-Pr2)2-4-SiMe3) shows that it has a Sn-Sn bond length = 3.066(1) A and a Sn-Sn-C bending angle of 99.25(14) degrees . These parameters differ by about 0.4 A and about 26 degrees from those previously reported for the closely related Ar'SnSnAr' (Ar' = C6H3-2,6-(C6H3-2,6-i-Pr2)2). The results show that, in accordance with the theoretical predictions by Nagase and Takagi, very small amounts of energy (ca. 5 kcal mol-1) separate structural isomers of distannynes that have large differences in their bonding parameters.

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Three chiral vinyldioxazaborocanes.

The structures of three chiral vinyldioxazaborocanes are reported, namely (2E)- and (2Z)-6-benzyl-2-buten-2-yl-1,3,6,2-dioxazaborocane, C27H30BNO2, (II) and (III), respectively, and (2Z)-2-buten-2-yl-6-isobutyl-1,3,6,2-dioxazaborocane, C24H32BNO2, (IV). These compounds may be useful in asymmetric reactions. In the structures reported here, the N-B donor-acceptor bond is longer than in any previously reported analogous compounds.

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A pirouette on a metallofullerene sphere: interconversion of isomers of N-tritylpyrrolidino I(h) Sc3N@C80.

The pure I(h) isomer of Sc3N@C80 was allowed to react with N-triphenylmethyl-5-oxazolidinone via the corresponding azomethine ylide. The reaction results in the formation of two monoadducts; one (1b) is the kinetic product, and the other (1a) is thermodynamically more stable. Small amounts of the bisadducts were also formed. The structure of the thermodynamic monoadduct 1a was shown conclusively by NMR spectroscopy and X-ray crystallography to result from addition across the 5,6-ring junction. The kinetic product 1b was demonstrated to be the 6,6-ring juncture adduct on the basis of NMR experiments and X-ray crystallography. In refluxing chlorobenzene pure 1b was converted to the more thermodynamically stable 1a isomer. These N-tritylpyrrolidino derivatives are potentially useful precursor compounds for further derivatization for various applications.

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Diazocinones: synthesis and conformational analysis.

1,2,4,5-Tetrazines (prepared from aryl nitriles) condense with isoxazolylcyclobutanones (prepared from 3-benzenesulfonyl-3-vinylcyclobutanol) in methanolic KOH to give conformationally restricted 6-isoxazol-5-yl-6,7-dihydro-5H-[1,2]diazocin-4-ones. The solution 1H NMR spectra of dihydrodiazocinone 1a with phenyl moieties at C3 and C8 reveal two conformations of the eight-membered heterocycle that are non-interconverting on the NMR time scale at ambient temperature. The kinetics of the conversion process, followed by 1H NMR between 21 and 70 degrees C in DMSO solution, yield an activation energy of approximately 21 kcal/mol relative to the kinetic conformer and show an equilibrated ratio of approximately 5:1 of the thermodynamic to the kinetic conformers. The electronic structure calculations on a model dihydrodiazocinone predict geometries for the two conformations. One of these geometries agrees with the X-ray crystallographic analysis of the thermodynamic conformation of 1a.

Azocines↗

Living Ziegler-Natta polymerization by early transition metals: synthesis and evaluation of cationic zirconium alkyl complexes bearing beta-hydrogens as models for propagating centers.

The synthesis and characterization of a series of cationic zirconium and hafnium complexes with alkyl substituents bearing beta-hydrogens of general formula {(eta(5)-C5Me5)MR[N(Et)C(Me)N(t-Bu)]}[B(C6F5)4] [M = Zr; R = Et, n-Pr, i-Pr, n-Bu, i-Bu, and 2-ethylbutyl (5a-f) and M = Hf; R = i-Bu and t-Bu (6 and 7, respectively)] is described, including several isotopically labeled derivatives. The ability of these complexes to serve as model complexes for the living Ziegler-Natta polymerization of olefins that can be effected using the initiator 2a (R = Me in 5) has been addressed. The results obtained shed additional light on the steric and electronic factors that can contribute to the living character of a Ziegler-Natta polymerization based on an early transition metal initiator.

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Three-dimensional nets from star-shaped hexakis(arylthio)triphenylene molecules and silver(I) salts.

This article reports a number of functional 3D networks based on the coordination bonds between the silver(I) ion and polycyclic aromatic 2,3,6,7,10,11-hexakis(organylthio)triphenylene (HRTT) molecules. First, 2,3,6,7,10,11-hexakis(phenylthio)triphenylene (HPhTT) chelates with AgBF4 (or AgTf, where Tf is triflate) in the presence of hexafluorobenzene to form a 3D network (composition, HPhTT x AgBF4; space group, I4), where each Ag(I) atom is bonded to three HPhTT molecules and acts as a three-connected node that interconnects the trigonal HPhTT ligands. In addition to the relatively rare 8(2) x 10-a topology, the network features distinct channel-like domains that incorporate various solvent molecules (e.g., acetone and tetrahydrofuran). The solvent molecules can be evacuated to produce a stable and crystalline apohost network, in which the solvent-accessible fraction of the cell volume is calculated to be about 16%. Second, chelation of 2,3,6,7,10,11-hexakis(4-methoxyphenylthio)triphenylene (HMOPhTT) and AgSbF6 in a 1:1 ratio results in a 3D network featuring a similar 8(2) x 10-a topology and Ag(I) coordination environment. However, the crystallographic symmetry (space group Cc) is lowered, and the feature of porosity is much less distinct. The 3D networks show strong room-temperature fluorescence bands with lambda(F,max) = 450 nm, due to the pi-electron fragment of the triphenylene group.

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Metal-metal interactions in thallium(I)/platinum(II) compounds involving a chelating dicarbene and various auxiliary ligands.

Reaction of Tl(I)NO(3) and (C(4)H(10)N(4))Pt(II)(mnt) or (C(4)H(10)N(4))Pt(II)(dmg-H) [mnt = maleonitriledithiolate, dmg-H = dimethylglyoximate dianion] in dilute, aqueous KOH yielded adducts of Tl(I) and the conjugate bases of the platinum(II) compounds. The compound Tl(I)[(C(4)H(9)N(4))Pt(II)(dmg-H)].5H(2)O forms as dimers with close Tl(I)...Pt(II) separations of 3.0843(5) A, while Tl(I)[(C(4)H(9)N(4))Pt(II)(mnt)] has much longer Tl(I)...Pt(II) separations of 3.4400(2) A and forms loosely associated, helical coordination polymers. The new compounds are compared with the red and yellow polymorphs of Tl(I)[(C(4)H(9)N(4))Pt(II)(CN)(2)], and the influences of crystal packing forces, Coulombic interactions, and hydrogen bonding on supramolecular structures and Tl(I)...Pt(II) separations are discussed.

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Synthesis, structure, and dynamic properties of [Ni2Sn17]4-.

The ligand-free [Ni2Sn17]4- ion comprises two [Ni@Sn9]2- clusters that share a common vertex. The cluster sequentially loses Sn atoms in the gas phase and shows global exchange of all Sn atoms on the NMR time scale in solution at 60 degrees C. At lower temperatures, the fluxionality is localized to the ends of the cluster and does not involve the central 8-coordinate Sn5 atom.

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Four psychrotolerant species with high chemical diversity consistently producing cycloaspeptide A, Penicillium jamesonlandense sp. nov., Penicillium ribium sp. nov., Penicillium soppii and Penicillium lanosum.

Penicillium jamesonlandense is a novel species from Greenland that grows exceptionally slowly at 25 degrees C and has an optimum temperature for growth of 17-18 degrees C. The novel species is more psychrotolerant than any other Penicillium species described to date. Isolates of this novel species produce a range of secondary metabolites with a high chemical diversity, represented by kojic acid, penicillic acid, griseofulvin, pseurotin, chrysogine, tryptoquivalins and cycloaspeptide. Penicillium ribium, another novel psychrotolerant species from the Rocky Mountains, Wyoming, USA, produces asperfuran, kojic acid and cycloaspeptide. Originally reported from an unidentified Aspergillus species isolated from Nepal, cycloaspeptide A is reported here for the first time from the two novel Penicillium species and two known psychrotolerant species with high chemical diversity, Penicillium soppii and Penicillium lanosum. All species, except P. ribium, produce a combination of cycloaspeptide and griseofulvin. However, P. ribium (3/5 strains) produced the precursor to griseofulvin, norlichexanthone. The type strain of Penicillium jamesonlandense sp. nov. is DAOM 234087(T) (=IBT 21984(T) = IBT 24411(T) = CBS 102888(T)) and the type strain of Penicillium ribium sp. nov. is DAOM 234091(T) (=IBT 16537(T) = IBT 24431(T)).

Genetic Variation↗

Reactions of the heavier group 14 element alkyne analogues Ar'EEAr' (Ar' = C6H3-2,6(C6H3-2,6-Pri2)2; E = Ge, Sn) with unsaturated molecules: probing the character of the EE multiple bonds.

Reactions of the alkyne analogues Ar'EEAr' (Ar' = C6H3-2,6(C6H3-2,6-Pr(i)2)2; E = Ge (1); Sn (2)) with unsaturated molecules are described. Reaction of 1 and 2 with azobenzene afforded the new hydrazine derivatives Ar'E{(Ph)NN(Ph)}EAr' (E = Ge (3); Sn (4)). Treatment of 1 with Me3SiN3 gave the cyclic singlet diradicaloid Ar'Ge{mu2-(NSiMe3)}2GeAr' (5), whereas 2 afforded the monoimide bridged Ar'Sn{mu2-N(SiMe3)}SnAr' (6). Reaction of 1 with t-BuNC or PhCN yielded the adduct Ar'GeGe(CNBu(t))Ar' (7) or the ring compound (8). In contrast, the tin compound 2 did not react with either t-BuNC or PhCN. Treatment of 1 with N2CH(SiMe3) generated Ar'Ge{mu2-CH(SiMe3)}{mu2:eta2-N2CH(SiMe3)}{mu2-N2CH(SiMe3)}GeAr' (9) which contains ligands in three different bridging modes and no Ge-Ge bonding. Reaction of 1 with an excess of N(2)O gave a germanium peroxo species Ar'(HO)Ge(mu2-O)(mu2:eta2-O2)Ge(OH)Ar' (10) which features a ring. Oxidation of 1 by tetracyanoethylene (TCNE) led to cleavage of the Ge-Ge bond and formation of a large multiring system of formula Ar'Ge3+{(TCNE)2-}3{(GeAr')+}3. The digermyne 1 also reacted with 1 equiv of PhCPh to give the 1,2-digermacyclobutadiene 12, which has a ring, and with Me(3)SiCCH or PhCC-CCPh to activate a flanking C6H3-2,6-Pr(i)2 ring and give the tricyclic products 13 and 14. The "distannyne" 2 did not react with these acetylenes. Overall, the experiments showed that 1 is highly reactive toward unsaturated molecules, whereas the corresponding tin congener 2 is much less reactive. A possible explanation of the reactivity differences in terms of the extent of the singlet diradical character of the Ge-Ge and Sn-Sn bonds is discussed.

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Cucurbit[n]uril analogues: synthetic and mechanistic studies.

[reaction: see text] The synthesis of cucurbit[n]uril analogues (18, 19, (+/-)-20, 33, 34, 35, 36, and 37) is presented. These CB[5], CB[6], and CB[7] analogues all contain bis(phthalhydrazide) walls that are incorporated into the macrocycle. The tailor-made synthesis of these CB[n] analogues proceeds by the condensation of the appropriate bis(electrophile) (4, 7, or 9) with bis(phthalhydrazide) (17), which delivers the CB[6] and CB[7] analogues in good yield, whereas the CB[5] analogue is formed in low yield. To improve the solubility characteristics of the CB[n] analogues for recognition studies in water or organic solution, the CO2Et groups were transformed to CO2H and CO2(CH2)9CH3 groups. On the basis of the results of product resubmission experiments, we conclude that these macrocycles are kinetic products. To help rationalize the good yields obtained in the CB[6] and CB[7] analogue macrocyclization reactions, we performed mechanistic studies of model methylene bridged glycoluril dimers, which suggest an intramolecular isomerization during CB[n] analogue formation.

Bridged-Ring Compounds↗

Synthesis of a stable compound with fivefold bonding between two chromium(I) centers.

Although in principle transition metals can form bonds with six shared electron pairs, only quadruply bonded compounds can be isolated as stable species at room temperature. Here we show that the reduction of {Cr(mu-Cl)Ar'}2 [where Ar' indicates C6H3-2,6(C6H3-2,6-Pri2)2 and Pr indicates isopropyl] with a slight excess of potassium graphite has produced a stable compound with fivefold chromium-chromium (Cr-Cr) bonding. The very air- and moisture-sensitive dark red crystals of Ar'CrCrAr' were isolated with greater than 40% yield. X-ray diffraction revealed a Cr-Cr bond length of 1.8351(4) angstroms (where the number in parentheses indicates the standard deviation) and a planar transbent core geometry. These data, the structure's temperature-independent paramagnetism, and computational studies support the sharing of five electron pairs in five bonding molecular orbitals between two 3d5 chromium(I) ions.

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