Solid-state multinuclear magnetic resonance and X-ray crystallographic investigation of the phosphorus...iodine halogen bond in a bis(dicyclohexylphenylphosphine)(1,6-diiodoperfluorohexane) cocrystal

Abstract

Halogen bonding to phosphorus atoms remains uncommon, with relatively few examples reported in the literature. Here, the preparation and investigation of the cocrystal bis(dicyclohexylphenylphosphine)(1,6-diiodoperfluorohexane) by X-ray crystallography and solid-state multinuclear magnetic resonance spectroscopy is described. The crystal structure features two crystallographically unique C—I...P halogen bonds [d I...P = 3.090 (5) Å, 3.264 (5) Å] and crystallographic disorder of one of the 1,6-diiodoperfluorohexane molecules. The first of these is the shortest and most linear I...P halogen bond reported to date. 13C, 19F, and 31P magic angle spinning solid-state NMR spectra are reported. A 31P chemical shift change of −7.0 p.p.m. in the cocrystal relative to pure dicyclohexylphenylphosphine, consistent with halogen bond formation, is noted. This work establishes iodoperfluoroalkanes as viable halogen bond donors when paired with phosphorus acceptors, and also shows that dicyclohexylphenylphosphine can act as a practical halogen bond acceptor.

Heavy pnicogen atoms as electron donors in sigma-hole bonds

“…F, O, and N. There is surprisingly little information concerning the capability of the larger base atoms to act as electron donors in this class of s-hole bonds. [69][70][71][72][73] Given the growing consensus on their participation within HBs, this neglect leaves a large hole in our understanding of these other sorts of related bonds.…”

Crystallographic evidence for Bi(I) as the heaviest halogen bond acceptor

“…using tertiary phosphines. [14][15][16] In a seminal work, Friščić and Cinčić reported the successful cocrystallization of the halogen bond donor 1,3,5-trifluoro-2,4,6-triiodobenzene with Ph3P, Ph3As and Ph3Sb. However, no adduct could be isolated in case of Ph3Bi.…”