The rhenium(V) ethylene glycolate complex [ReO(OCH2CH2O){B(pz)(4)}] (1) has been prepared in one step synthesis by reacting [ReOCl3(SMe(2))(OPPh(3))] or [ReOCl3(PPh(3))2(]) with ethylene glycol and K[B(pz)4(]) (50-60% isolated yield). Complex 1 reacts with 2-mercaptoethanol and with 1,2-ethanedithiol in the presence of triethylamine providing respectively [ReO(OCH2CH2S){B(pz)(4)}] (2) and [ReO(SCH2CH2S){B(pz)(4)}] (3) in 70-75% isolated yield. These compounds have been characterized by elemental analyses, IR and H-1 NMR spectroscopies, and, in the case of compound 1, X-ray crystallography. Compound 1 crystallizes from toluene/hexane in the orthorhombic space group Pbca with cell parameters a = 15.255(1) Angstrom, b = 22.442(3) Angstrom, c = 20.960(2) Angstrom, V = 7176 Angstrom(3), and Z = 16. The ethylene glycolate complex 1 reacts with HCl providing in almost quantitative yield [ReO{B(pz)(4)}-Cl-2] (4). Compound 4 is reduced by several phosphines giving compounds of general formula [Re{B(pz)(4)}Cl(2)L] (L = PEt(3) (5), PEt(2)Ph (6), PEtPh(2) (7), and PPh(3) (8) in 60-70% yield. These paramagnetic compounds were characterized by elemental analyses, IR and H-1 and P-31 NMR spectroscopies, and, in the case of compound 6, X-ray crystallography. Compound 6 crystallizes from tetrahydrofuran/hexane in the monoclinic space group P2(1)/a with cell parameters a = 14.187(2) Angstrom, b = 11.985(1) Angstrom, c = 15.535(2) Angstrom, beta = 91.40(1)degrees, V = 2641 Angstrom(3), and Z = 4. The redox behavior of all the complexes and of K[B(pz)(4)] was studied by cyclic voltammetry.