Rhenium(I) Tricarbonyl Complexes with Poly(azolyl)borates Generated in Situ from an Organometallic Precursor Containing the B-H•••Re Coordination Motif

Complex fac-[Re(kappa(3)-H(mu-H)(2)B(tim(Me)))(CO)(3)] (1) reacts with protic azoles, like 2-mercapto-1-methylimidazole (timM(8)H), 2-mercaptobenzothiazole (bztH), or pyrazoles (pz*H), to afford fac-[Re(kappa(3)-H(mu-H)B(tim(Me))(2)(CO)(3)] (2), fac-[Re(kappa(3)- H(mu-H)B(tim(Me))(bzt))(CO)(3)] (3), fac-[Re(kappa(3)-H(mu-H)B(tim(Me))(pz))(CO)(3)] (4), fac-[Re(kappa(3)-HB(tim(Me))(pz)(2))(CO)(3)] (5), and fac- [Re(kappa(3)-H(mu-H)B(tim(Me))(3,5-Me-2-4-EtOOCCH(2)pz))(CO)(3)] (6). Complexes 2- 6 are stabilized by tridentate poly(azolyl)borates generated in situ, and their formation involves most probably a metal-assisted process which is considerably faster for the pyrazole derivatives. The characterization of the novel complexes, 3-6, has been done by common analytical techniques, including single crystal X-ray diffraction analysis. The solid state structures confirmed the presence of hybrid heteroscopionates, presenting (kappa(3)-H, S, S'), (kappa(3)-H, S, N), or (kappa(3)-S, N, N) binding motifs. Multinuclear (H-1, C-13, and B-11) NMR studies have also shown that the coordination mode found in the solid state is retained in solution.