Bridging Carbonyl and Carbyne Complexes of Weak-Field Iron: Electronic Structure and Iron-Carbon Bonding.

Carbon monoxide inhibited forms of nitrogenases have carbonyl (CO) and carbide (C) bridges, which are common in synthetic iron complexes with strong-field ligand environments but rare in iron sites with weak-field ligand environments analogous to the enzyme. Here, we explore the fundamental bonding description of bridging CO in high-spin iron systems. We describe the isolation of several diiron carbonyls and related species, and elucidate their electronic structures, magnetic coupling, and characteristic structural and vibrational parameters.

The HSmacropa Series: Increasing the Chemical Softness of Hmacropa with Sulfur Atoms to Chelate Radiometals [Bi]Bi and [Pb]Pb for Radiopharmaceutical Applications.

The effects of replacing nitrogen with sulfur atoms in the 18-membered macrocycle of the Hmacropa chelator on the binding affinity and stability of "intermediate" (radio)metal [Pb]Pb and [Bi]Bi complexes are investigated. The 1,4,10,13-tetraoxo-7,16-diazacyclooctadecane backbone was replaced with derivatives containing sulfur in the 1,4- or the 1,4,10,13-positions to yield the novel chelators HSmacropa (NOS) and HSmacropa (NOS), respectively. Trends on the Pb- and Bi-complex stability constants, coordination chemistry, radiolabeling, and kinetic inertness were assessed via potentiometric titrations, UV-vis spectroscopy, NMR spectroscopy, X-ray crystallography and density functional theory (DFT) calculations.

-Oxide Coordination to Mn(III) Chloride.

We report on the synthesis and characterization of Mn(III) chloride (MnCl) complexes coordinated with -oxide ylide ligands, namely trimethyl--oxide (MeNO) and pyridine--oxide (PyNO). The compounds are reactive and, while isolable in the solid-state at room temperature, readily decompose into Mn(II). For example, "[MnCl(ONMe)]" decomposes into the 2D polymeric network compound complex salt [Mn(µ-Cl)Mn(µ-ONMe)][Mn(µ-Cl)]·(MeNO·HCl) ().

Synthesis of Mn(III)X (X = Cl, Br, I) Compounds with Phosphine (RP) Ligands.

This work details the synthesis and characterization of complexes of the form [MnX(PR)] (X = Cl, Br, I), which is a rare type of coordination compound. Prior to this work, the only mode of synthesis was oxidizing mixtures of MnX and PR with dry air, but these procedures give low yields and variable outcomes. By taking advantage of the starting material [MnCl(OPPh)] () and other new strategies, we present robust synthetic protocols for both new and known Mn(III) halido phosphine complexes.