ortho-bis(cyanomercurio)tetrafluorobenzene as a bidentate Lewis acid co-catalyst in the cyanosilylation of benzaldehyde
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
Reaction of o-C 6 F 4 (HgCl) 2 (1), m-C 6 F 4 (HgCl) 2 (2), C 6 F 5 HgCl (3), and C 6 F 4 H(HgCl) (4) with TMSCN in MeCN affords the corresponding organomercury cyanide derivatives o-C 6 F 4 (HgCN) 2 (5), m-C 6 F 4 (HgCN) 2 (6), C 6 F 5 HgCN (7), and C 6 F 4 H(HgCN) (8), respectively. These compounds have been characterized by elemental analysis, 1 H, 13 C, 19 F, and 199 Hg NMR, and IR spectroscopy. The infrared spectra of 5-8 display a cyanide stretching band in the range 2170-2183 cm -1 , while their 199 Hg NMR chemical shifts are all within the range -1170 to -1250 ppm. The crystal structures of [2DMF], [5MeCOH], [5PhCOH], and 8 have been determined. In [2DMF], the DMF molecule acts as a terminal ligand and coordinates one of the mercury centers through the formation of a Hg-O bond of 2.746(14) . A similar situation is encountered in [5MeCOH] and [5PhCOH], wherein the aldehyde ligand is terminally ligated to one of the mercury centers through a Hg-O bond of 2.855(19) and 3.009(12) , respectively. In these compounds, the neighboring molecules engage in long intermolecular HgN contacts. In [5MeCOH], these interactions lead to the formation of a hexameric aggregate whose shape is reminiscent of a capsule. The ability of 5-8 to catalyze the cyanosilylation of benzaldehyde has been studied. While little or no product formation is observed when the pure cyanide derivatives 5-8 are employed as catalysts, their combination with TMSCl leads to the formation of active catalytic species. The combination of bidentate 5 and TMSCl provides the most active system. The results are rationalized on the basis of a working model in which TMSCl is activated by the halophilic bidentate fluorinated mercury derivative 5, which produces a catalytically active Lewis acidic silicon species.
