Fa. Jalon et al., SYNTHESIS AND NUCLEAR-MAGNETIC-RESONANCE STUDIES OF HALOGENO AND HYDRIDO TRIS(PYRAZOL-1-YL)BORATO RUTHENIUM(II) COMPLEXES, Journal of the Chemical Society. Dalton transactions, (10), 1995, pp. 1629-1633
The reaction of polymeric [{RuCl2(cod)}(n)] (cod = cycloocta-1,5-diene
) with potassium tris(pyrazol-1-yl)borate, KHB(pz)(3), in refluxing te
trahydrofuran leads to [Ru{HB(pz)(3)}Cl(cod)] 1, and the pyrazole-cont
aining [RuCl2(Hpz)(2)(cod)] 2 which arises from thermolysis of pyrazol
ylborate. Reaction of [RuCl2(tht)(4)] (tht = tetrahydrothiophene) with
the same salt at room temperature affords a mixture of [RU{HB(pz)(3)}
Cl(tht)(2)] 3 and [Ru{HB(pz)(3)}(2)(tht)(2)] 4, which have been effici
ently isolated. The product ratio of this process greatly depends on t
he reaction conditions. The compound [Ru{HB(pz)(3)}(2)] 5 forms by tra
nsformation of 4 in chloroform solution, a reaction which is slow but
complete in one week. The compound [RuClH(bpzm)(cod)] [bpzm = bis(pyra
zol-1-yl)methane] reacts with KHB(pz)(3) to give [Ru{HB(pz)3}H(cod)] a
s the only ruthenium product. Nuclear Overhauser enhancement (NOE) mea
surements have been used as a valuable method for the assignment of th
e H-3 and H-5 resonances of the pyrazolyl groups. Heteronuclear H-1-C-
13 correlation (COSY) experiments have been recorded to determine the
assignment of the C-3 and C-5 carbons of the pz groups.