“…[9] The NgÀ F bonds of the NgF 2 ligand become more polarized, consistent with the calculated FIAs of the Group 6 oxide tetrafluorides (CrOF 4 , À 285; MoOF 4 , À 355 WOF 4 , À 386 kJ mol À 1 ), [12] which ). [9] Similar trends have been noted for other terminally coordinated NgF 2 (Ng = Kr, Xe) adducts: [F 2 OBr (FNgF) 2 AsF 6 ], [13,14] [Mg(FKrF) 4 (AsF 6 ) 2 ], [15] [F 5 Xe(FNgF) n AsF 6 ] (n = 1, 2), [16,17] and [Hg(FKrF) 8 ][AsF 6 ] 2 . [18] The MoÀ O (Kr, 1.6508( 12 3) Å) bond lengths are comparable to those of the infinite-chain MoOF 4 [19] and tetrameric WOF 4 structures, [20] and gaseous monomeric MOF 4 (Mo, [21] W [22] ).…”