Rhenium tricarbonyl core complexes with ligands derived from arylpiperazines. The structures of [Re(CO)3{NC5H4CH2N(H)CH2CH2–Fphenpip}]Br, [Re(CO)3{(NC5H4CH2)2N(CH2)3–CH3OphenpipH}]Br2 and [Re(CO)3{(CH3N2C3H2CH2)(O2CCH2)N(CH2)3–CH3OphenpipH2}]BrCl

The reactions of potentially tridentate ligands, derived from N-arylpiperazines, with [NEt4]2[Re(CO)3Br3] have been investigated. The compounds [Re(CO)3{NC5H4CH2N(H) CH2CH2–Fphenpip}]Br (1Br), [Re(CO)3{(NC5H4CH2)2NCH2CH2CH2–CH3OphenpipH}]Br2 · 2CH2Cl2 · H2O (2Br2 · 2CH2Cl2 · H2O) and [Re(CO)3{(CH3N2C3H2CH2)(O2CCH2)N(CH2)3–CH3OphenpipH2}]BrCl · 1.5MeOH · H2O (3BrCl · 1.5MeOH · H2O) have been prepared and structurally characterized. The compounds exhibit fac-[Re(CO)3N3] or fac-[Re(CO)3N2O] coordination geometry in the cationic molecular units. Both compounds are chemically robust and survive histidine and cysteine challenges with greater than 95% recovery. Crystal data for C21H23BrFN4O3Re (1Br): monoclinic P21/c, a=11.344(1) Å, b=14.433(1) Å, c=13.730(1) Å, β=103.092(2)°, V=2189.5(2) Å3, Z=4; C31H41Br2Cl4N5O5Re (2Br2 · 2CH2Cl2 · H2O): monoclinic P21/c, a=30.015(1) Å, b=8.9324(4) Å, c=14.7361(6)Å, β=103.195(1)°, V=3846.5(3) Å3, Z=4; C25.5H39BrClN5O8.5Re (3BrCl · 1.5MeOH · H2O): triclinic P1̄, a=11.818(2) Å, b=13.292(2) Å, c=14.517(2) Å, α=63.915(2)°, β=66.373(2)°, γ=67.416(2)°, V=1815.6(4) Å3, Z=2.