title: Syn-Anti Isomerism in a Mixed-Ligand Oxorhenium Complex, ReO[SN(R)S][S].
abstract: The simultaneous action of the tridentate ligand (C(2)H(5))(2)NCH(2)CH(2)N(CH(2)CH(2)SH)(2) and the monodentate coligand HSC(6)H(4)OCH(3) on a suitable ReO(3+) precursor results in a mixture of syn- and anti-oxorhenium complexes, ReO[(C(2)H(5))(2)NCH(2)CH(2)N(CH(2)CH(2)S)(2)] [SC(6)H(4)OCH(3)], in a ratio of 25/1. The complexes are prepared by a ligand exchange reaction using ReO(eg)(2) (eg = ethylene glycol), ReOCl(3)(PPh(3))(2), or Re(V)-citrate as precursor. Both complexes have been characterized by elemental analysis, FT-IR, UV-vis, X-ray crystallography, and NMR spectroscopy. The syn isomer C(17)H(29)N(2)O(2)S(3)Re crystallizes in the monoclinic space group P2(1)/n, a = 14.109(4) Å, b = 7.518(2) Å, c = 20.900(5) Å, beta = 103.07(1) degrees, V = 2159.4(9) Å(3), Z = 4. The anti isomer C(17)H(29)N(2)O(2)S(3)Re crystallizes in P2(1)/n, a = 9.3850(7) Å, b = 27.979(2) Å, c = 8.3648(6) Å, beta = 99.86(1) degrees, V = 2163.9(3) Å(3), Z = 4. Complete NMR studies show that the orientation of the N substituent chain with respect to the Re=O core greatly influences the observed chemical shifts. Complexes were also prepared at the tracer ((186)Re) level by using (186)Re-citrate as precursor. Corroboration of the structure at tracer level was achieved by comparative HPLC studies.
authors.affiliation: Institutes of Radioisotopes-Radiodiagnostic Products, Biology, and Materials Science, NCSR "Demokritos", POB 60228, 15310, Aghia Paraskevi, Athens, Greece.
authors.forename: M. S.
authors.initials: MS
authors.lastname: Papadopoulos
authors.forename: I. C.
authors.initials: IC
authors.lastname: Pirmettis
authors.forename: M.
authors.initials: M
authors.lastname: Pelecanou
authors.forename: C. P.
authors.initials: CP
authors.lastname: Raptopoulou
authors.forename: A.
authors.initials: A
authors.lastname: Terzis
authors.forename: C. I.
authors.initials: CI
authors.lastname: Stassinopoulou
authors.forename: E.
authors.initials: E
authors.lastname: Chiotellis