Metal hydrides form halogen bonds: measurement of energetics of binding

Dan A Smith; Lee Brammer; Christopher A Hunter; Robin N Perutz

doi:10.1021/ja4121499

Metal hydrides form halogen bonds: measurement of energetics of binding

J Am Chem Soc. 2014 Jan 29;136(4):1288-91. doi: 10.1021/ja4121499. Epub 2014 Jan 14.

Authors

Dan A Smith¹, Lee Brammer, Christopher A Hunter, Robin N Perutz

Affiliation

¹ Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.

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.