Formaldehyde as Tethering Organocatalyst: Highly Diastereoselective Hydroaminations of Allylic Amines.

Catalysts possessing sufficient activity to achieve intermolecular alkene hydroaminations under mild conditions are rare, and this likely accounts for the scarcity of asymmetric variants of this reaction. Herein, highly diastereoselective hydroaminations of allylic amines utilizing hydroxylamines as reagents and formaldehyde as catalyst are reported. This catalyst induces temporary intramolecularity, which results in high rate accelerations, and high diastereocontrol with either chiral allylic amines or chiral hydroxylamines.

Hydrogen bonding directed intermolecular Cope-type hydroamination of alkenes.

Intermolecular hydroamination of unactivated alkenes represents a significant synthetic challenge. An efficient Cope-type hydroamination is achieved under mild conditions for reactions of N-alkylhydroxylamines with allylic amines, using hydrogen bonding to achieve increased reactivity and high regioselectivity. This approach provides a number of highly functionalized vicinal diamine motifs as Markovnikov addition products.

Electrophilic fluorination of cationic Pt-aryl complexes.

The electrophilic fluorination of several (triphos)Pt-aryl(+) establishes the first example of aryl-F coupling from a Pt center.

Steric Crowding Makes Challenging C(sp3)-F Reductive Eliminations Feasible.

A high-yielding fluorination of (triphos)Pt-R(+) has been achieved using an array of F(+) sources, with XeF(2) yielding R-F in minutes. The C-F coupling proved to be a stereoretentive process that proceeds via a concerted reductive elimination from a putative dicationic Pt(IV) center. The larger the steric congestion of the (triphos)Pt-C(sp3) (+) complexes, the more efficient the fluorination, seemingly a result of sterically accelerated C-F reductive elimination along with simultaneous deceleration of its competing processes (β-H elimination).

{Bis[2-(diphenyl-phosphan-yl)eth-yl]phenyl-phosphane-κP,P',P''}[(Z)-8-mesityl-cyclo-oct-4-en-1-yl]platinum(II) tetra-fluorido-borate dichloro-methane disolvate.

In the title ionic compound, [Pt(C(17)H(23))(C(34)H(33)P(3))](BF(4))·2CH(2)Cl(2), the Pt(II) atom adopts a square-planar coordination geometry with the large (Z)-8-mesityl-cyclo-oct-4-en-1-yl group occupying the fourth coordination site. The (triphos)Pt moiety and the mesityl group are attached to the cyclo-oct-4-ene motif at the 1- and 8-position in a syn configuration. The (BF(4))(-) anion and one of the dichloromethane solvate molecules each are disordered over two sets of sites.

Luminescence and reactivity of 7-azaindole derivatives and complexes.

7-Azaindole and its derivatives have been extensively investigated for uses in biological probes and imaging. In contrast, there have been very limited studies on the coordination chemistry and the applications of 7-azaindole and derivatives in materials science and in chemical bond activation. Our recent research has shown that 7-azaindolyl and derivatives are excellent blue emitters for organic light emitting diodes, they have rich coordination chemistry with both main group elements and transition metal ions, and their metal complexes display not only phosphorescence but also unusual and often unprecedented reactivity toward C-H and C-X bonds.

Switchable ambient-temperature singlet-triplet dual emission in nonconjugated donor-acceptor triarylboron-Pt(II) complexes.

A triarylboron compound Si-BNPA (1) containing a BMes(2) acceptor and an N-(2'-pyridyl)-7-azaindolyl (NPA) donor linked by a tetrahedral silane group has been synthesised. This molecule displays unusual white singlet-triplet dual emission at 77 K, with an exceptionally long phosphorescent decay time (2.2 s).

Impact of the linker groups in bis(7-azaindol-1-yl) chelate ligands on structures and stability of Pt(N,N-L)R(2) complexes.

New organoplatinum(II) complexes with the general formula of Pt(N,N-L)R(2), where L is a bis(7-azaindol-1-yl) chelate ligand, R is a methyl or a phenyl, have been synthesized and investigated with the aim to understand the impact of the linker group in the L ligand on the structure and the stability of the Pt(II) complexes. The L ligands used in our investigation belong to two classes: class I with an aliphatic linker between two 7-azaindolyl groups such as -CH(2)- (BAM), -(CH(2))(3)- (1,3-BAPr), and -(CH(2))(4)- (1,4-BABu), class II with an aromatic linker such as 1,2-phenyl (1,2-BAB) 1,3-phenyl (1,3-BAB) and 1,4-dihydronaphthalene-1,4-epoxide (BAHE). The structures of these new mononuclear Pt(II) complexes have been determined by single-crystal X-ray diffraction analyses.

Reversible intramolecular C-C bond formation/breaking and color switching mediated by a N,C-chelate in (2-ph-py)BMes2 and (5-BMes2-2-ph-py)BMes2.

A diboron compound with both 3-coordinate boron and 4-coordinate boron centers, (5-BMes2-2-ph-py)BMes2 (1) and its monoboron analogue, (2-ph-py)BMes2 (2) have been synthesized. Both compounds are luminescent but have a high sensitivity toward light. UV and ambient light cause both compounds to isomerize to 1a and 2a, respectively, via the formation of a C-C bond between a mesityl and the phenyl group, accompanied by a drastic color change from yellow or colorless to dark olive green or dark blue.

Ambient-temperature metal-to-ligand charge-transfer phosphorescence facilitated by triarylboron: Bnpa and its metal complexes.

A Cu(I) complex, 1, and a Pt(II) complex, 2a, of a triarylboron ligand, Bnpa, with bright ambient-temperature phosphorescence have been obtained. The phosphorescence of these complexes is highly sensitive toward molecular oxygen and has a distinct response to fluoride ions. For 1, the fluoride ion causes phosphorescent quenching and Bnpa dissociation, and for 2a, it switches phosphorescent color from yellow to green.

Dinuclear Cu(I) complexes of 1,2,4,5-tetra(7-azaindolyl)benzene: persistent 3-coordinate geometry, luminescence, and reactivity.

Five Cu(I) complexes [Cu2(ttab)(CH3CN)2][BF4]2 (1), [Cu(2)(ttab)(PPh3)2][BF4]2 (2), [Cu2(ttab)I2] (3), [Cu2(ttab)(I3)2] (4), and [Cu2(ttab)(I)BF4]n (5) with 1,2,4,5-tetra(7-azaindolyl)benzene (ttab) have been synthesized and characterized. The structures of compound 1, 2, 4, and 5 have been determined by single-crystal X-ray diffraction analyses, which established that 1, 2, and 4 are discrete dinuclear Cu2 compounds while compound 5 is a 1D coordination polymer with the I- ligand bridging two dinuclear Cu2 units. The ttab ligand in all four complexes adopts a 1,3-chelation mode.