The complex [Re{eta(3)-B(pz)(4)}(OMe)(2)] (1) reacts with potentially bidentate protic substrates yielding several monomeric and dimeric oxorhenium compounds in which the tetrakis(pyrazolyl)borate presents different coordination modes : [ReO(acac){eta(2)-B(pz)(4)}(OMe)] (3), [ReO(acac){eta(2)-B(pz)(4)}](2)(mu-O) (4), [ReO(eta(2)-B(pz)(4)}-(quinolin-8-olate)(OMe)] (5), [ReO{eta(2)-B(pz)(4)}(OMe)(pz*)(pz*H)](pz* = pz (6) or 3,5-Me(2)pz (7)), [ReO{eta(2)-B(pz)(4)}(mu-pz*)](2)(mu-O) (pz* = pz (9) or 3,5-Me(2)pz (10)), [ReO(HNCH2CH2NH){eta(3)-B(pz)(4)}] (14), and [ReO(m-nitrophenyl-o-diaminate){eta(3)-B(pz)(4)}] (15). Using the analogous alkoxide [ReO{eta(3)-B(pz)(4)}(OEt)(2)] (2), the compound [ReO{eta(2)-B(pz)(4)}(OEt)(pz)(pzH)] (8) has also been obtained. Compounds 3 and 5 react with trimethylsilyl chloride providing the monochlorides [ReO(acac){eta(2)-B(pz)(4)}Cl] (12) and [ReO{eta(2)-B(pz)(4)}(quinolin-8-olate)Cl] (13), respectively. Compounds 9, 10, and 14 were also prepared by reacting [ReO{mu-O){B(pz)(4)}](2) (11) with the respective substrates. The new compounds 3-10 and 12-15 were characterized by elemental analysis and IR and H-1 NMR spectroscopies. Compounds 3, 4, and 9 have also been characterized by X-ray crystallography. Compounds 3 and 4 both crystallize in the monoclinic space group P2(1)/c, with a = 7.862(1) Angstrom, b = 14.152(2) Angstrom, c = 19.975(3) Angstrom, beta = 91.79(1)degrees, V = 2221(1) Angstrom(3) and Z = 4 (3) and a = 13.547(2) Angstrom, b = 9.959(1) Angstrom, c = 15.878(2) Angstrom, beta = 102.00(1)degrees, V = 2095(1) Angstrom(3) and Z = 2 (4). Compound 9 crystallizes in the monoclinic space group P2(1), with cell parameters a = 11.086(2) Angstrom, b = 15.269(1) Angstrom, c = 12.133(1) Angstrom, beta 93.51(1)degrees, V = 2050(1) Angstrom(3) and Z = 2.