Search

The first consistent series of mononuclear 17-electron complexes of three Group 7 elements has been isolated in crystalline form and studied by X-ray diffraction and spectroscopic methods. The paramagnetic compounds have a composition of [M0(CO)(CNp-F-ArDarF2)4] (M = Mn (1), Tc (3), Re (6); ArDArF2 = 2,6-(3,5-(CF3)2C6H3)2­C6H3)) and are stabilized by four sterically encumbering isocyanides, which prevent the metalloradicals from dimerization. They have a square pyramidal structure with the carbonyl ligands as apexes. The frozen-solution EPR spectra of the rhenium and technetium compounds are clearly anisotropic with large 99Tc and 185,187Re hyperfine interactions for one component. High-field EPR (Q band and W band) has been applied for the elucidation of the EPR parameters of the manganese(0) complex.

[Re(CO)Br(CNArDArF2)4] and [Tc(CO)Cl(CNArDArF2)4] (ArDArF = 2,6-(3,5-(CF3)2C6H3)2-4-F-C6H2) were prepared by reactions of [Re(CO)5Br] or (NBu4)[Tc2(CO)6(μ-Cl)3] with the sterically encumbered isocy...

A new synthetic route to complexes of the type Ni(P2N2)22+ with highly functionalized phosphine substituents and the investigation of immobilization effects on these catalysts is reported. Ni(P2N2)22+ complexes have been extensively studied as homogeneous and surface-attached molecular electrocatalysts for the hydrogen evolution reaction (HER). A synthesis based on postsynthetic modification of PArBr2NPh2 was developed and is described here. Phosphonate-modified ligands and their corresponding nickel complexes were isolated and characterized. Subsequent deprotection of the phosphonic ester derivatives provided the first Ni(P2N2)22+ catalyst that can be covalently attached via pendent phosphonate groups to an electrode without involvement of the important pendent amine groups. Mesoporous TiO2 electrodes were surface modified by attachment of the new phosphonate functionalized Ni(P2N2)22+ complexes, and these provided electrocatalytic materials that proved to be competent and stable for sustained HER in aqueous solution at mild pH and low overpotential. We directly compared the new ligand to a previously reported complex that utilized the amine moiety for surface attachment. Using HER as the benchmark reaction, the P-attached catalyst showed a marginally (9-14%) higher turnover number than its N-attached counterpart.

A series of technetium complexes with the sterically encumbered m-terphenyl isocyanides CNArDipp2 (Dipp = 2,6-diisopropylphenyl) and CNArMes2 (Mes = 2,4,6-trimethylphenyl) has been prepared. The pr...

2 + 2 Photocycloadditions are idealized, convergent construction approaches of 4-membered heterocyclic rings, including azetidines. However, methods of direct excitation are limited by the unfavorable photophysical properties of imines and electronically unbiased alkenes. Here, we report copper-catalyzed photocycloadditions of non-conjugated imines and alkenes to produce a variety of substituted azetidines. Design principles allow this base metal-catalyzed method to achieve 2 + 2 imine-olefin photocycloaddition via selective alkene activation through a coordination-MLCT pathway supported by combined experimental and computational mechanistic studies.

Relative to other cyclic poly-phosphorus species (that is, cyclo-Pn ), the planar cyclo-P4 group is unique in its requirement of two additional electrons to achieve aromaticity. These electrons are supplied from one or more metal centers. However, the degree of charge transfer is dependent on the nature of the metal fragment. Unique examples of dianionic mononuclear η4 -P4 complexes are presented that can be viewed as the simple coordination of the [cyclo-P4 ]2- dianion to a neutral metal fragment. Treatment of the neutral, molybdenum cyclo-P4 complexes Mo(η4 -P4 )I2 (CO)(CNArDipp2 )2 and Mo(η4 -P4 )(CO)2 (CNArDipp2 )2 with KC8 produces the dianionic, three-legged piano stool complexes, [Mo(η4 -P4 )(CO)(CNArDipp2 )2 ]2- and [Mo(η4 -P4 )(CO)2 (CNArDipp2 )]2- , respectively. Structural, spectroscopic, and computational studies reveal a similarity to the classic η6 -benzene complex (η6 -C6 H6 )Mo(CO)3 regarding the metal-center valence state and electronic population of the planar-cyclic ligand π system.

The mixed isocyanide/carbonyl complexes cis- and trans-[Re(CO)3Br(CNArDipp2)2] (ArDipp2 = 2,6-(2,6-(i-Pr)2C6H3)2C6H3) can be synthesized from reactions of [Re(CO)5Br] and CNArDipp2 depending on the conditions applied. Reduction of the neutral Re(I) species gives the monoanionic complex [Re(CO)3(CNArDipp2)2]− or the neutral [Re(CO)3(CNArDipp2)2], which contain rhenium in the formal oxidation states “−1” and “0”, respectively.

While interest in cooperative reactivity of transition metals and Lewis acids is receiving significant attention, the scope of known reactions that directly exploit the polarized reverse-dative σ-bond of metal-borane complexes (i.e., M→BR3) remains limited. Described herein is that the platinum (boryl)iminomethane (BIM) complex [Pt(κ2-N,B-Cy2BIM)(CNArDipp2)] can effect the oxidative insertion of a range of unsaturated organic substrates, including azides, isocyantes, and nitriles, as well as CO2 and elemental sulfur (S8). In addition, alkyl migration processes available to the BIM framework allow for post-insertion reaction sequences resulting in product release from the metal center.

Relative to other cyclic poly-phosphorus species (that is, cyclo-P

Summary While splice modulators have entered clinical trials, limited clinical efficacy in splicing factor mutation-driven malignancies, such as acute myeloid leukemia, has remained a challenge. There is a pressing unmet medical need for developing potent small molecule splice modulators for the treatment of a broad array of malignancies characterized by splicing deregulation. However, the inability to practically access gram-scale lead molecules with viable pharmacological properties continues to hinder their application. Here, we report a scalable approach to prepare 17S-FD-895, a potent in vivo active splice modulator. The strategy described herein not only provides material to enable clinical translation but also furthers lead validation by expanding the structure-activity relationships that guide splice modulation.