Functionalised Tris(pyrazolyl)methane Ligands and Re(CO)(3) Complexes Thereof

The synthesis of new tripodal nitrogen ligands derived from tris(pyrazolyl)methane (Tpm R, R = H, tBu, Ph in 3-position) is described. After deprotonation of the parent tris(pyrazolyl)methane Tpm(R), the carbanion reacts readily with ethylene oxide to ligands yield the 3,.3,3-tris(3'-substituted pyrazolyl)propanol [(3-Rpz)(3)CCH2CH2OH, R = H, tBu, Ph, 1a-c]. These ligands can be easily derivatised at the alcohol function. Microwave-assisted reactions of these ligands and [Re(CO)(5)Br] yields the complex [(1a)Re(CO)(3)]Br (4) in the case of ligand la, whereas in the case of the substituted ligands 1b and 1c degradation was observed. The degradation products are identified as [(Hpz(R))(2)Re(CO)(3)Br] [R = tBu (7b), Ph (7c)]. These complexes were also prepared directly from [Re(CO)5Br] and the corresponding pyrazoles by microwave-assisted synthesis. The Re(CO)3 complexes 4 and [(1a)Re(CO)(3)]OTf (5) are water-soluble. The structures of 5-HO and [{(pz)(3)CCH2Cu3}Re(CO)(3)]OTf center dot 1.5H(2)O.1/2CH(3)CN (6 center dot 1.5H(2)O1/2CH(3)CN) as well as the structure of 7b have been elucidated by X-ray crystallography.