title: Metal hydrides form halogen bonds: measurement of energetics of binding.
abstract: The formation of halogen bonds from iodopentafluorobenzene and 1-iodoperfluorohexane to a series of bis(η(5)-cyclopentadienyl)metal hydrides (Cp2TaH3, 1; Cp2MH2, M = Mo, 2, M = W, 3; Cp2ReH, 4; Cp2Ta(H)CO, 5; Cp = η(5)-cyclopentadienyl) is demonstrated by (1)H NMR spectroscopy. Interaction enthalpies and entropies for complex 1 with C6F5I and C6F13I are reported (ΔH° = -10.9 ± 0.4 and -11.8 ± 0.3 kJ/mol; ΔS° = -38 ± 2 and -34 ± 2 J/(mol·K), respectively) and found to be stronger than those for 1 with the hydrogen-bond donor indole (ΔH° = -7.3 ± 0.1 kJ/mol, ΔS° = -24 ± 1 J/(mol·K)). For the more reactive complexes 2-5, measurements are limited to determination of their low-temperature (212 K) association constants with C6F5I as 2.9 ± 0.2, 2.5 ± 0.1, <1.5, and 12.5 ± 0.3 M(-1), respectively.
authors.affiliation: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors.forename: Dan A
authors.initials: DA
authors.lastname: Smith
authors.forename: Lee
authors.initials: L
authors.lastname: Brammer
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Hunter
authors.forename: Robin N
authors.initials: RN
authors.lastname: Perutz