Mohamed S. Loonat

Synthesis of ferrocenylruthenocene

SummaryThe dinuclear metallocene, ferrocenylruthenocene, is synthesized by Ullmann coupling of iodoruthenocene with a large excess of iodoferrocene in the melt phase. The compounds ligand-vibrational modes, as reflected in the i.r. spectrum, are virtually identical with those in biferrocene; so is the symmetric ring-metal-ring stretching mode manifested in the low-frequency Raman region. The mass-spectral fragmentation pattern indicates preferential loss of a cyclopentadienyl radical from the ferrocene rather than the ruthenocene unit in conformance with both the lower metal-ring bond strength in, and lower ionization energy of, the iron complex. The1H n.m.r. patterns of the two metallocene groups, at 90 MHz, are sufficiently well separated from each other to allow their individual evaluation; this finding could have a significant bearing on the characterization of ferrocenylene-ruthenocenylene copolymers of future synthetic programs.

Substituted cyclopentadienyl complexes. Part 4. The catalysed synthesis and proton nuclear magnetic resonance spectra of [Ru(η5-C5H4Me)(CO)(L)I] and [Ru(η5-C9H7)(CO)(L)I](L = phosphine or isocyanide) and the crystal structure determination of [Ru(η5-C9H7)(CO){P(CH2Ph)3}I]

The reaction between [Ru(η5-C5H4Me)(CO)2I] and L [L = P(OMe)3, P(OEt)3, P(OPri)3, PPh3, PMe2Ph, ButNC, or 2,6-Me2C6H3NC] or [Ru(η5-C9H7)(CO)2I] and L [L = P(OMe)3, P(OEt)3, P(OPri)3, P(OC6H4Me-o)3, PPh3, or P(CH2Ph)3] in the presence of [{Fe(η5-C5H5)(CO)2}2] as catalyst yields the new substituted products [Ru(η5C5H4Me)(CO)(L)I], (1) and [Ru(η5-C9H7)(CO)(L)I], (2). The new products have been characterized by a combination of i.r. and n.m.r. spectroscopy and mass spectrometry. Ring proton resonances of complexes (1) have been assigned by nuclear Overhauser enhancement (n.O.e.) spectra [L = P(OMe)3, PMe2Ph, PMePh2, or 2,6-Me2C6H3NC]. The n.O.e. spectra also reveal preferential conformations of the cyclopentadienyl ring when L is large. Such spectra were also recorded for complexes (2)[L = P(OC6H4Me-o)3 or P(CH2Ph)3] and together with coupling constant data are consistent with a ligand orientation in which L = P(CH2Ph)3 is found preferentially under the central carbon atom of the cyclopentadienyl indenyl ring. This was further confirmed by a crystal structure determination of [Ru(η5-C9H7)(CO){P(CH2Ph)3}I]·0.5C6H6: space group P, Z= 2, a= 9.923(2), b= 11.055(4), c= 14.543(3)A, α= 84,52(2), β= 77.72(2), γ= 82.74(2)°, and R= 0.0560.

Substituted cyclopentadienyl complexes: VII. An NMR and X-ray crystallographic study of [(η5-C5H4R)Fe(CO)(PPh3)I] (R = CHPh2, I, CH(CH3)2)☆

The complexes [(η5-C5H4R)Fe(CO)(PPh3)I] (R = I (1), CH(CH3)2 (2), CHPh2 (3)) have been synthesised. The NOE spectra recorded on the new complexes reveal a preferential conformation of the ring substituent on 3, with the H atom of the benzhydryl group pointing towards the PPh3 ligand. A similar effect is not observed in the spectrum of 2. The phenomenon is related to the steric effect associated with the relative sizes of the ring substitutents. The crystal structures of 1 and 3 have been determined. The results for 3 suggest that the dominant conformer observed in solution corresponds to the solid state structure.