Synthesis, characterisation and crystal structures of new water-soluble 1-alkanaminedicarbonyl(η5-cyclopentadienyl)ruthenium(II) tetrafluoroborate complex salts

•Stable and water soluble 1-alkanamine ruthenium(II) complex salts were synthesised.•The complex salts were characterised by IR, NMR and X-ray crystallography.•The 1-alkanamine is σ-bonded to the metal centre via nitrogen as the donor atom.•The molecules are held together by N–H…F–B and C–H…F bonds.•Molecules generally adopt the energetically favoured gauche type conformation.

New water-soluble 1-alkanaminedicarbonyl(η5-cyclopentadienyl)ruthenium(II) tetrafluoroborate complex salts, [CpRu(CO)2NH2R]+BF4− (Cp = η5-C5H5) (R = CH31, C2H52, C3H73, C4H94, C5H115 and C6H136), were synthesised by the reaction of the organometallic Lewis acid, [CpRu(CO)2]+BF4, with slight excesses of 1-alkanamines, RNH2, in dry methylene chloride at room temperature and pressure. These compounds are reported for the first time and have been fully characterised by IR, electrospray ionisation mass spectroscopy, 1H and 13C NMR spectroscopy, and elemental analysis. Spectral data show that the n-alkanamines are σ-bonded to the metal centre via the nitrogen atom. Complexes 2–5 were characterised by single crystal X-ray diffraction and all four cationic species feature a “pseudo-octahedral three-legged piano stool” structure in which the ruthenium centre is coordinated through a sigma bond to the amine N atom and two carbonyl ligands at the base of the stool and the cyclopentadienyl ring in the apex of the stool. IR studies showed that peaks of the νCO stretching vibrations shifted slightly to lower frequency as the carbon chain length increased. The melting point and percentage yields were observed to generally decrease with increase in n-value.

Graphical abstractNew water-soluble 1-alkanaminedicarbonyl(η5-cyclopentadienyl)ruthenium(II) tetrafluoroborate complex salts, [CpRu(CO)2NH2R]+BF4− (Cp = η5-C5H5) (R = CH31, C2H52, C3H73, C4H94, C5H115 and C6H136), were synthesised. These compounds have been fully characterised by IR, electrospray ionisation mass spectroscopy, 1H and 13C NMR spectroscopy, and elemental analysis. Spectral data show that the n-alkanamines are σ-bonded to the metal centre via the nitrogen atom. Complexes 2–5 were characterised by single crystal X-ray diffraction and all four cationic species feature a “pseudo-octahedral three-legged piano stool” structure in which the ruthenium centre is coordinated through a sigma bond to the amine N atom and two carbonyl ligands at the base of the stool and the cyclopentadienyl ring in the apex of the stool.Figure optionsDownload full-size imageDownload as PowerPoint slide