High oxidation state rhodium and iridium bis(silyl)dihydride complexes supported by a chelating pyridyl-pyrrolide ligand.

New rhodium and iridium complexes containing the bidentate ligand 3,5-diphenyl-2-(2-pyridyl)pyrrolide (PyPyr) were prepared. The bis(ethylene) complex (PyPyr)Rh(C(2)H(4))(2) (3) reacted with HSiEt(3), HSiPh(3), and HSi(t)BuPh(2) to produce the 16-electron Rh(V) bis(silyl)dihydrides (PyPyr)Rh(H)(2)(SiEt(3))(2) (8), (PyPyr)Rh(H)(2)(SiPh(3))(2) (9), and (PyPyr)Rh(H)(2)(Si(t)BuPh(2))(2) (10), respectively. The analogous Ir(V) bis(silyl)dihyride (PyPyr)Ir(H)(2)(SiPh(3))(2) (11) has also been synthesized.

Germylene and silylene complexes of molybdenum via E-H (E = Ge, Si) bond activations: steric influences on intramolecular MoH...E interactions.

Reactions of Cp*(dmpe)Mo(eta(3)-CH(2)Ph) with organogermanes (RR'GeH(2)) afforded germylene complexes Cp*(dmpe)Mo(H)GeRR' (RR' = Ph(2) (2), Et(2) (3), (Mes)H (4), ((t)Bu)H (5)). Compound 2 does not possess an intramolecular H..

Mechanistic studies of the hydroamination of norbornene with electrophilic platinum complexes: the role of proton transfer.

Hydroaminations of norbornene with arylsulfonamides and weakly basic anilines were achieved using electrophilic Pt(II) bis(triflate) complexes of the type L2Pt(OTf)2 (L2 = (t)Bu2bpy, (t)BuC6H4N== C(CH3)C(CH3)==NC6H4(t)Bu, (C6H5)2PCH2CH2P(C6H5)2, (C6F5)2PCH2CH2P(C6F5)2, S-BINAP). Pseudo-first-order kinetics reveal little to no dependence of the reaction rate on the ancillary ligand. Mechanistic studies do not favor an olefin coordination mechanism but are instead consistent with a mechanism involving sulfonamide coordination and generation of an acidic proton that is transferred to the norbornene.

Zirconocene-mediated macrocyclizations of diynes containing di-o-methylphenylene spacers.

The diynes 3,3',5,5'-tetramethyl-4,4'-di(pent-1-ynyl)biphenyl (4) and 3,3'',5,5''-tetramethyl-4,4''-di(hex-1-ynyl)terphenyl (9) undergo coupling with Cp(2)Zr(eta(2)-Me(3)SiC[triple bond]CSiMe(3))(py) to give dimeric macrocycles in moderate yields (16% for 4 and 26% for 9).

Mesityl alkyne substituents for control of regiochemistry and reversibility in zirconocene couplings: new synthetic strategies for unsymmetrical zirconacyclopentadienes and conjugated polymers.

Reaction of 2 equivs of MesC[triple bond]CPh with Cp(2)Zr(eta(2)-Me(3)SiC[triple bond]CSiMe(3))(pyr) afforded the zirconacyclopentadiene Cp(2)Zr[2,5-Ph(2)-3,4-Mes(2)C(4)]. The regiochemistry of this isomer (betabeta with respect to the mesityl substituents) was determined through single-crystal X-ray analysis and 2D (NOESY, HSQC, HMBC) NMR experiments. This selectivity is attributed largely to a steric-based directing effect of the o-methyl ring substituents since coupling of 1,3-dimethyl-2-(phenylethynyl)benzene with zirconocene gave a single regioisomer (o-xylyl groups in both beta-positions) while coupling of 1,3-dimethyl-5-(phenylethynl)benzene gave a statistical distribution of zirconacyclopentadiene regioisomers.

Stereoselective macrocyclization through zirconocene-mediated coupling of achiral dialkynes.

1,4-Bis[trimethylsilyl(ethynyl)]naphthalene () and 1,4-bis[trimethylsilyl(ethynyl)]anthracene () undergo diastereoselective coupling with Cp2Zr(py)(Me3SiC[triple bond, length as m-dash]CSiMe3) to give trimeric macrocycles in good yield.

2,7-Substituted hexafluoroheterofluorenes as potential building blocks for electron transporting materials.

A series of 2,7-substituted hexafluoro-9-heterofluorenes was synthesized via nucleophilic aromatic substitution (S(N)Ar(F)) reactions of phenyllithium, thienyllithium, and lithium phenylacetylide with various octafluoroheterofluorenes and 2,2'-dibromooctafluorobiphenyl. These compounds are of interest as possible building blocks for materials with useful electron transport properties, since they possess relatively low LUMO energy levels. The HOMO-LUMO energy gaps, as determined by UV-vis spectroscopy, range between 3.

Synthesis and characterization of 2,7-bis(pentafluorophenylethynyl)hexafluoroheterofluorenes: new materials with high electron affinities.

The synthesis, optical, electrochemical and physical characterization of 2,7-bis(pentafluorophenylethynyl)hexafluoroheterofluorenes is described along with a preliminary evaluation of their performance in photovoltaic applications.

9,10-Disubstituted octafluoroanthracene derivatives via palladium-catalyzed cross-coupling.

9,10-Dichlorooctafluoroanthracene (1) reacts with aryl boronic acids and terminal alkynes under palladium-catalyzed cross-coupling conditions to afford 9,10-diaryloctafluoroanthracenes (2a-e) and 9,10-dialkynyloctafluoroanthracenes (6a,b), respectively. Optical spectroscopy and cyclic voltammetry indicate that octafluoro-9,10-di(thiophen-2-yl)anthracene (2d) exhibits donor-acceptor character and a LUMO energy level of -3.27 eV relative to vacuum.

Mechanism of reversible alkyne coupling at zirconocene: ancillary ligand effects.

The mechanism of reversible alkyne coupling at zirconium was investigated by examination of the kinetics of zirconacyclopentadiene cleavage to produce free alkynes. The zirconacyclopentadiene rings studied possess trimethylsilyl substituents in the alpha-positions, and the ancillary Cp2, Me2C(eta(5)-C5H4)2, and CpCp* (Cp* = eta(5)-C5Me5) bis(cyclopentadienyl) ligand sets were employed. Fragmentation of the zirconacyclopentadiene ring in Cp2Zr[2,5-(Me3Si)2-3,4-Ph2C4] with PMe3, to produce Cp2Zr(eta(2)-PhC[triple bond]CSiMe3)(PMe3) and free PhC[triple bond]CSiMe3, is first-order in initial zirconacycle concentration and zero-order in incoming phosphine (k(obs) = 1.

9,10-Dichlorooctafluoroanthracene as a building block for n-type organic semiconductors.

9,10-Dichlorooctafluoroanthracene (1) was synthesized from commercially available tetrafluorophthalic acid by an optimized solution-phase route. To establish 1 as a synthon for n-type organic semiconductors, the compound was reacted with phenylboronic acid under modified Suzuki-Miyaura coupling conditions to generate octafluoro-9,10-diphenylanthracene (7) in high yield. Cyclic voltammetry and X-ray crystallography indicate that 7 has a stabilized LUMO energy level and exhibits extended pi stacking, which should lead to efficient electron transport in solid-state devices.

Rational design and synthesis of porous organic-inorganic hybrid frameworks constructed by 1,3,5-benzenetriphosphonic acid and pyridine synthons.

1,3,5-Benzenetriphosphonic acid, H6BTP, 1,3,5-[(HO)2OP]3C6H3, was reacted hydrothermally with copper salts in the absence and presence of 4,4'-bipyridine (bpy) and 4,4'-trimethlyenedipyridine (tbpy) in a 1:1 molar ratio leading to three new organic-inorganic hybrid frameworks. Compound 1, {Cu6[C6H3(PO3)3]2(H2O)8} x 5.5 H2O, has three different copper ions that are interconnected by the highly charged [1,3,5-(PO3)3C6H3]6- anionic moieties.