[(F6acac)Pd(µ-HNC6F5)]2, a Large Family of Polymorphs and Solvates with Short F···F Contacts.

Highly fluorinated [(F6acac)Pd(µ-HNC6F5)]2 was prepared by the reaction of palladium bis(hexafluoroacetylacetonate), Pd(F6acac)2, with pentafluoroaniline. This compound generates a large family of crystalline polymorphs and solvates. In this paper, we present a study on the synthesis, solution phase dynamics, and crystal structures of highly fluorinated [(F6acac)Pd(µ-HNC6F5)]2. Pd3(µ-F6acac)2(µ-HNC6F5)4 is produced as a minor byproduct. We also describe the synthesis and structural characterization of trinuclear Pd3(µ-F6acac)3[µ-(CF3)2C=N]3 prepared by the reaction of Pd(F6acac)2 with hexafluoroacetone imine.

Evidence of CF2 Loss from Fluorine-Rich Cluster Anions Generated from Laser Ablation of Graphite Fluoride.

A mass spectrometric analysis of the anionic and cationic species generated by laser ablation of graphite fluoride (GF) and graphite targets performed under identical sets of conditions is presented. Under conditions that produce typical C n- cluster mass distributions from ablation of graphite, the mass spectra of anionic species generated by ablation of GF are congested with overlapping stoichiometric patterns such as C nF2 n and C nF(2 n-2). Some of the molecular formulas for these clusters, such as C6F6, C6F12, and C7F8, are evocative of stable neutral fluorocarbons. Additionally, the GF-ablation generated mass peaks broaden at higher masses more than the graphite-based counterparts, which may indicate cluster fragmentation. Furthermore, a pattern of fragmentation via loss of CF2 is observed and is reminiscent of previous studies which determined CF2 loss during thermal decomposition. No species were seen in the mass spectra of the cationic species generated from laser ablation of GF, while, under the same conditions, typical C n+ cluster distributions were observed.

Reductive defluorination of graphite monofluoride by weak, non-nucleophilic reductants reveals low-lying electron-accepting sites.

Graphite monofluoride (GF) can undergo reductive defluorination in the presence of weak, non-nucleophilic reductants. This leads to a new approach to GF-polyaniline composites as cathode materials for significantly improving the discharge capacity of primary lithium batteries. We postulate that the reduction is mediated by residual π-bonds in GF.

Photothermally induced Bergman cyclization of metalloenediynes via near-infrared ligand-to-metal charge-transfer excitation.

Reaction of 1,2-bis(tert-butyldimethylsilyloxy)-4,5-diiodobenzene with 2 equiv of phenylacetylene followed by deprotection with KF/HBr yields the catechol-enediyne ligand 4,5-bis(phenylethynyl)benzene-1,2-diol (CatED, 1). Metathesis of VO(SALIMH)ACAC.CH(3)OH (2) with 1 and subsequent air oxidation yields (4,5-bis(phenylethynyl)-1,2-dihydroxyphenyl)[4-(2-(salicylideneamino)ethyl)imidazolyl]oxovanadium(V).CH(3)OH [VO(SALIMH)CatED], (3), in 85%. The thermal Bergman cyclization temperature for 3 is very high (246 degrees C), which is expected for a rigid, benzannulated enediyne motif. The electronic spectrum of 3 exhibits two strong ligand-to-metal charge transfer (LMCT) transitions centered at 584 nm (epsilon = 6063 M(-)(1) cm(-)(1)) and 1028 nm (epsilon = 8098 M(-)(1) cm(-)(1)). These transitions derive from CatED-to-V(V) ligand-to-metal charge transfer, the assignment of which is verified by resonance enhancement of several CatED vibrational modes in the Raman spectra obtained with lambda = 785 vs lambda = 457.9 nm under low power and/or temperature conditions. At elevated temperatures (113-323 K) and powers (2-5 mW), excitation of 3 in the solid state with lambda = 785 nm leads to generation of a black, sparingly soluble, fluorescent product that exhibits weak vibrational features in the 580-600, 1200-1350, and 1450-1600 cm(-)(1) regions, indicative of V-O (CatED) and aromatic ring units. The C=C ring modes correspond well with the vibrational characteristics of poly(p-phenylene) and derivatives thereof. Additionally, materials generated in both the solid-state thermal and photothermal reactions of 3 demonstrate the formation of high molecular weight species ranging from 5000 to 274 000. On the basis of these data and the literature precedent for formation of poly(p-phenylene) via thermolysis of simple enediynes, the reaction poses a unique approach for photoinitiating Bergman cyclization with long-wavelength excitation, as well as the generation of polymeric products.