A Structurally Diverse Series of Eight-Coordinate Hg2+ Complexes of KrF2 Derived from Hg(PnF6)2 (Pn = As, Sb) and FHg(AsF6).

Low-temperature (LT) reactions of the strong oxidative fluorinator, KrF2, with Hg(PnF6)2 (Pn = As, Sb) and FHg(AsF6) in anhydrous HF solvent provide a structurally diverse series of eight-coordinate Hg(II) complexes in which Hg2+ is coordinated to KrF2, [PnF6]- (Pn = As, Sb), and HF. The complexes, [Hg(FKrF)5(AsF6)2] (1), [Hg(FKrF)4(FH)2SbF6]2[SbF6]2 (2), [Hg(FKrF)3(FH)(SbF6)2] (3), [Hg(FKrF)2(AsF6)2] (4), [Hg(FKrF)(FH)(AsF6)2] (5), [Hg(FKrF)4(FH)(FH---FH)(AsF6)2] (6), [μ-FHg(μ3-FKrF)1.5(FKrF)0.5AsF6]2 (7), and [μ3-FHg(μ3-FKrF)0.5(FKrF)1.5AsF6]2 (8), were characterized by LT single-crystal X-ray diffraction and LT Raman spectroscopy. Complexes 2, 3, 5, and 6 are the only KrF2 coordination complexes known in which a second neutral donor, HF, is coordinated to the metal center. The series of complexes exhibits three coordination modalities for KrF2. In addition to Hg2+ coordination through a single fluorine atom of KrF2, complex 7 provides a rare example of a KrF2 ligand that bridges two Hg2+ cations by coordination through both of its fluorine atoms, and complexes 7 and 8 provide unique examples of μ3-FKrF coordination in which a single fluorine atom of KrF2 bridges two Hg2+ cations. Although quantum-chemical calculations show that electrostatic contributions dominate bonding of Hg2+ to μ3-coordinated KrF2 in the model cation, [μ-F(HgF)2(μ3-FKrF)2]+, orbital contributions are also significant.

A Structurally Diverse Series of Eight-Coordinate Hg2+ Complexes of KrF2 Derived from Hg(PnF6)2 (Pn = As, Sb) and FHg(AsF6). Journal Articles