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(κ3-H(μ-H)2B(timMe))(CO)3] (1) reacts with protic azoles, like 2-mercapto-1-methylimidazole (timMeH), 2-mercaptobenzothiazole (bztH), or pyrazoles (pz*H), to afford fac-[Re(κ3-H(μ-H)B(timMe)2(CO)3] (2), fac-[Re(κ3-H(μ-H)B(timMe)(bzt))(CO)3] (3), fac-[Re(κ3-H(μ-H)B(timMe)(pz))(CO)3] (4), fac-[Re(κ3-HB(timMe)(pz)2)(CO)3] (5), and fac-[Re(κ3-H(μ-H)B(timMe)(3,5-Me2-4-EtOOCCH2pz))(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 (κ3-H, S, S′), (κ3-H, S, N), or (κ3-S, N, N) binding motifs. Multinuclear (1H, 13C, and 11B) NMR studies have also shown that the coordination mode found in the solid state is retained in solution.