title: The Contrasting Character of Early and Late Transition Metal Fluorides as Hydrogen Bond Acceptors.
abstract: The association constants and enthalpies for the binding of hydrogen bond donors to group 10 transition metal complexes featuring a single fluoride ligand (trans-[Ni(F)(2-C5NF4)(PR3)2], R = Et 1a, Cy 1b, trans-[Pd(F)(4-C5NF4)(PCy3)2] 2, trans-[Pt(F){2-C5NF2H(CF3)}(PCy3)2] 3 and of group 4 difluorides (Cp2MF2, M = Ti 4a, Zr 5a, Hf 6a; Cp*2MF2, M = Ti 4b, Zr 5b, Hf 6b) are reported. These measurements allow placement of these fluoride ligands on the scales of organic H-bond acceptor strength. The H-bond acceptor capability β (Hunter scale) for the group 10 metal fluorides is far greater (1a 12.1, 1b 9.7, 2 11.6, 3 11.0) than that for group 4 metal fluorides (4a 5.8, 5a 4.7, 6a 4.7, 4b 6.9, 5b 5.6, 6b 5.4), demonstrating that the group 10 fluorides are comparable to the strongest organic H-bond acceptors, such as Me3NO, whereas group 4 fluorides fall in the same range as N-bases aniline through pyridine. Additionally, the measurement of the binding enthalpy of 4-fluorophenol to 1a in carbon tetrachloride (-23.5 ± 0.3 kJ mol(-1)) interlocks our study with Laurence's scale of H-bond basicity of organic molecules. The much greater polarity of group 10 metal fluorides than that of the group 4 metal fluorides is consistent with the importance of pπ-dπ bonding in the latter. The polarity of the group 10 metal fluorides indicates their potential as building blocks for hydrogen-bonded assemblies. The synthesis of trans-[Ni(F){2-C5NF3(NH2)}(PEt3)2], which exhibits an extended chain structure assembled by hydrogen bonds between the amine and metal-fluoride groups, confirms this hypothesis.
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Dan A
authors: DA
authors: Smith
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Torsten
authors: T
authors: Beweries
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Clemens
authors: C
authors: Blasius
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Naseralla
authors: N
authors: Jasim
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Ruqia
authors: R
authors: Nazir
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Sadia
authors: S
authors: Nazir
authors: Department of Chemistry, University of Sheffield , Sheffield, S3 7HF, U.K.
authors: Craig C
authors: CC
authors: Robertson
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Adrian C
authors: AC
authors: Whitwood
authors: Department of Chemistry, University of Cambridge , Cambridge, CB2 1EW, U.K.
authors: Christopher A
authors: CA
authors: Hunter
authors: Department of Chemistry, University of Sheffield , Sheffield, S3 7HF, U.K.
authors: Lee
authors: L
authors: Brammer
authors: Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K.
authors: Robin N
authors: RN
authors: Perutz