Deoxyfluorination of 1°, 2°, and 3° Alcohols by Nonbasic O-H Activation and Lewis Acid-Catalyzed Fluoride Shuttling.

A method for deoxyfluorination of aliphatic primary, secondary, and tertiary alcohols is reported, employing a nontrigonal phosphorus triamide for base-free alcohol activation in conjunction with an organic soluble fluoride donor and a triarylborane fluoride shuttling catalyst. Mechanistic experiments are consistent with a reaction that proceeds by the collapse of an oxyphosphonium fluoroborate ion pair with fluoride transfer. The substrate scope complements existing deoxyfluorination methods and enables the preparation of homochiral secondary and tertiary alkylfluorides by stereoinversion of the substrate alcohol.

Two-Site O-H Addition to an Iridium Complex Featuring a Nonspectator Tricoordinate Phosphorus Ligand.

The synthesis and reactivity of an ambiphilic iridium complex IrCl(PPh3)(L1) (1; L1 = P(N(o-N(2-pyridyl)C6H4)2)) featuring a chelating nontrigonal phosphorus triamide ligand is reported. The tandem Lewis basic Ir and Lewis acidic P of 1 achieve a two-site oxidative addition of phenol giving the iridaphenoxyphosphorane species IrHCl(PPh3)(L1OPh) (3'). In contrast, reactions of 1 with benzenethiol and benzeneselenol do not engage L1 and instead proceed via metal-centered oxidative addition of the chalcogen-hydrogen bond. These findings establish metal-ligand cooperation involving nonspectator reactivity of tricoordinate phosphorus ligands.

Controlled Expansion of a Strong-Field Iron Nitride Cluster: Multi-Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity.

Multimetallic clusters have long been investigated as molecular surrogates for reactive sites on metal surfaces. In the case of the µ4 -nitrido cluster [Fe4 (µ4 -N)(CO)12 ]- , this analogy is limited owing to the electron-withdrawing effect of carbonyl ligands on the iron nitride core. Described here is the synthesis and reactivity of [Fe4 (µ4 -N)(CO)8 (CNArMes2 )4 ]- , an electron-rich analogue of [Fe4 (µ4 -N)(CO)12 ]- , where the interstitial nitride displays significant nucleophilicity. This characteristic enables rational expansion with main-group and transition-metal centers to yield unsaturated sites. The resulting clusters display surface-like reactivity through coordination-sphere-dependent atom rearrangement and metal-metal cooperativity.

Terminal coordination of diatomic boron monofluoride to iron.

Boron monofluoride (BF) is a diatomic molecule with 10 valence electrons, isoelectronic to carbon monoxide (CO). Unlike CO, which is a stable molecule at room temperature and readily serves as both a bridging and terminal ligand to transition metals, BF is unstable below 1800°C in the gas phase, and its coordination chemistry is substantially limited. Here, we report the isolation of the iron complex Fe(BF)(CO)2(CNArTripp2)2 [ArTripp2, 2,6-(2,4,6-(i-Pr)3C6H2]2C6H3; i-Pr, iso-propyl], featuring a terminal BF ligand. Single-crystal x-ray diffraction as well as nuclear magnetic resonance, infrared, and Mössbauer spectroscopic studies on Fe(BF)(CO)2(CNArTripp2)2 and the isoelectronic dinitrogen (N2) and CO complexes Fe(N2)(CO)2(CNArTripp2)2 and Fe(CO)3(CNArTripp2)2 demonstrate that the terminal BF ligand possesses particularly strong σ-donor and π-acceptor properties. Density functional theory and electron-density topology calculations support this conclusion.