Craig A. Merlic

Charge ordering in the TMTTF family of molecular conductors

Using one- and two-dimensional NMR spectroscopy applied to 13C spin-labeled (TMTTF)2AsF6 and (TMTTF)2PF6, we demonstrate the existence of an intermediate charge-ordered phase in the TMTTF family of charge-transfer salts. At ambient temperature, the spectra are characteristic of nuclei in equivalent molecules. Below a continuous charge-ordering transition temperature T(co), there is evidence for two inequivalent molecules with unequal electron densities. The absence of an associated magnetic anomaly indicates only the charge degrees of freedom are involved and the lack of evidence for a structural anomaly suggests that charge-lattice coupling is too weak to drive the transition.

Distortion/Interaction Analysis Reveals the Origins of Selectivities in Iridium-Catalyzed C–H Borylation of Substituted Arenes and 5-Membered Heterocycles

The iridium-catalyzed borylation of mono- and disubstituted arenes and heteroarenes has been studied with density functional theory. The distortion/interaction model was employed to understand the origins of selectivities in these reactions. Computations revealed that the transition states for C-H oxidative addition are very late, resembling the aryl iridium hydride intermediate with a fully formed Ir-C bond. Consequently, the regioselectivity is mainly controlled by differences in the interaction energies between the iridium catalyst and arene carbon.

Copper-Promoted Coupling of Vinyl Boronates and Alcohols: A Mild Synthesis of Allyl Vinyl Ethers

A copper-promoted coupling of vinyl pinacol boronate esters and alcohols for the synthesis of enol ethers is reported. The reaction occurs in 50-99% yield and is compatible with a variety of functional groups. Cupric acetate is the copper source, and triethylamine buffer is used to prevent protodeboration; the reaction occurs at room temperature. In addition to excellent chemoselectivity, the reaction is stereospecific.

Theoretical Bond Dissociation Energies of Halo-Heterocycles: Trends and Relationships to Regioselectivity in Palladium- Catalyzed Cross-Coupling Reactions

Selectivity of the palladium-catalyzed cross-coupling reactions of heterocycles bearing multiple identical halogens is mainly determined by the relative ease of oxidative addition. This is related to both the energy to distort the carbon halogen bond to the transition-state geometry (related to the CX bond-dissociation energy) and to the interaction between the heterocycle pi* (LUMO) and PdL(2) HOMO (J. Am. Chem. Soc. 2007, 129, 12664). The computed bond dissociation energies of a larger series of halo-heterocycles have been explored with B3LYP and higher accuracy G3B3 calculations. Quantitative trends in bond dissociation energies have been identified for five- and six-membered chloro and bromo substituted heterocycles with N, O, and S heteroatoms.

Competition and coexistence of bond and charge orders in (TMTTF)2AsF6

(TMTTF) 2 AsF 6 undergoes two phase transitions upon cooling from 300 K. At T C O = 103 K a charge ordering (CO) occurs, and at T S P (B = 9 T) = 11 K the material undergoes a spin-Peierls transition. Within the intermediate, CO phase, the charge disproportionation ratio is found to be at least 3:1 from 1 3 C NMR T - 1 1 measurements on spin-labeled samples. Above T S P up to about 3T S P T - 1 1 is independent of temperature, indicative of low-dimensional magnetic correlations. With the application of about 0.15 GPa pressure, T S P increases substantially, while T C O is rapidly suppressed, demonstrating that the two orders are competing. The experiments are compared to results obtained from calculations on the one-dimensional extended Peierls-Hubbard model.

Benzannulation reactions of Fischer carbene complexes for the synthesis of indolocarbazoles

Abstract The synthesis of indolocarbazoles was achieved via photochemical and thermal annulation reactions of chromium Fischer carbene complexes. This methodology allows for facile incorporation of hydrogen bonding functionality which complements the pharmacophore contained within bioactive indolocarbazole natural products.

Electron-lattice coupling and broken symmetries of the molecular salt (TMTTF)2SbF6

The temperature/pressure phase diagram for

Alkoxydienes via copper-promoted couplings: utilizing an alkyne effect.

{(\mathrm{TMTTF})}_{2}{\mathrm{SbF}}_{6}

Synthesis of indolocarbazoles via sequential palladium catalyzed cross-coupling and benzannulation reactions

is determined using

Enol Silyl Ethers via Copper(II)-Catalyzed C–O Bond Formation

^{13}\mathrm{C}