The effect of the counteranion on the loss of hydrogen from cationic ruthenium dihydrogen complexes in the solid state

• Published in: Polyhedron 2018-12, Vol.156, p.342-349
• Main Authors: Trentowsky, Sandra E., Lough, Alan J., Morris, Robert H.
• Format: Article
• Language: English
• Subjects: Dihydrogen; Hydride; NMR; Phosphine; Ruthenium
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2018.09.056

A comparison of the structure and 31P CP MAS NMR spectrum of square pyramidal [RuH(dppe)2]BPh4 with that of octahedral [Ru(H2)H(dppe)2]BPh4 shows that only minor structural changes occur upon loss of the dihydrogen ligand and that this is a crystal to crystal reaction. [Display omitted] The loss of the dihydrogen ligand from trans-[Ru(H2)H(dppe)2]+ cations (dppe = PPh2CH2CH2PPh2) in the solid state was investigated using 31P CP/MAS NMR spectroscopy and single crystal X-ray diffraction. While facile dihydrogen loss was observed at room temperature from crystalline samples with the large counteranions BPh4− and B(ArF)4−, ArF = 3,5-C6H3(CF3)2, it only occurred upon heating from complexes with the smaller anions BF4− and PF6−, resulting in the loss of crystallinity. Single crystal X-ray diffraction studies of the new complexes [RuH(dppe)2]BPh4 and trans-[Ru(H2)H(dppe)2]BArF4 are reported. A comparison of the crystal structures of square pyramidal [RuH(dppe)2]BPh4 and octahedral [Ru(H2)H(dppe)2]BPh4 shows that only minor structural changes occur upon loss of H2 from the crystal.