1304511-79-2Relevant academic research and scientific papers
Intermolecular hydrogen-fluorine interaction in dimolybdenum triply bonded complexes modified by fluorinated formamidine ligands for the construction of 2D- and 3D-networks
Krackl, Sebastian,Inoue, Shigeyoshi,Driess, Matthias,Enthaler, Stephan
, p. 2103 - 2111 (2011/07/07)
The formamidines ArNHC(H)=N-Ar [Ar = Ph (2a), 4-F-Ph (2b), 3,5-F 2Ph (2c) and 2,6-F2Ph (2d) and R = 2,3,5-F3Ph (2e), 3,4,5-F3Ph (2f), F5Ph (2g) and 4-CF3Ph (2h)] were synthesized and the influence of the introduction of a fluorine or a trifluoromethyl group into the aryl unit on the solid-state structures was investigated. On comparing the experimental data, only marginal differences in the geometrical and electronic features of the diverse substituted species were detected. DFT calculations and X-ray crystallography of 2d-2g revealed that the E-syn-configuration corresponded to the thermodynamically most stable motif of all of the examined formamidines. However, in their solid-state, these ligands showed a range of H...F interactions, which varied depending on the number and position of the fluorine atoms on the aryl group and thus led to interesting solid-state structures. Moreover, compounds 2 were used for the synthesis of the new heteroleptic dimolybdenum triply-bonded complexes, Mo 2[(2a-2c; 2e-f)-H]2(OtBu)4 (3a-3c; 3e-3f). X-ray crystallography of complexes 3c and 3f revealed two different isomers in the solid state: in trans-3c the two formamidines are in one plane, while in cis-3c and cis-3f they are next to each other. The DFT calculations showed only a small distinction in energy between the configurations, which led us to assume that the different configurations were induced by the crystal packing. The specific H...F interactions provided by the different formamidines led to a two-dimensional arrangement for trans-3c and a three-dimensional network for cis-3c and cis-3f.
