The syntheses and structures of ‘3+2’ and ‘2+2+1’ oxorhenium mixed-ligand complexes employing 8-hydroxy-5-nitroquinoline as the bidentate NO donor ligand

摘要

The syntheses and structural characterizations of a series of novel ‘3+2’ and ‘2+2+1’ mixed-ligand complexes carrying 8-hydroxy-5-nitroquinoline (HL) as the bidentate N,O donor atom system are reported. Thus one-pot reactions of [ReOCl³(PPh3)2] with dianionic tridentate ligands H2Lⁿ (where H2L¹=HOC6H4-2-CH=NC6H4-2-OH; H2L²=HOC6H4-2-CH=N–C6H4-2-SH; H2L³=HOC6H4-2-CH=NN=C(NHC₆H₅)–SH; H₂L⁴=2-CH₂OH–C₅H₃N-6-CH₂SH; and H₂L⁵=2-CO₂H–C₅H₃N-6-CO₂H) and HL afforded a series of ‘3+2’ oxorhenium complexes of the type [ReO(H₂Lⁿ)(L)] >2–>6, which exhibit distorted octahedral geometries. Crystals of >1 are monoclinic space group C2/c, a=16.702(1), b=14.275(1), c=22.363(2) Å, β=108.083(1)° V=5068.2(7) Å^β and Z=8; those of >2 are monoclinic space group P2₁, a=8.5093(4) b=38.518(2), c=11.6092(5) Å, β=97.708(1)°, V=3770.7(3) ų and Z=8; those of >5 are triclinic, space group P1−, a=7.5899(8), b=10.322(1), c=11.905(1) Å, α=78.636(2)°, β=74.229(2)°, γ=71.391(2)°, V=844.3(2) ų, and Z=2. Upon reaction of 2,6-pyridinedimethanol (H₂L⁶) with the intermediate complex [ReOCl₂(L)(PPh₃)] (>1), only one of the two methylene hydroxy group was deprotonated and a new ‘2+2+1’ complex [ReO(OCH₃)(HL⁶)(L)]·CH₃OH (>7) was obtained. Crystal data for >7: monoclinic P2₁/n, a=12.0579(6), b=11.0993(6), c=14.9262(8) Å, β=107.872(1)°, V=1901.2(2) ų, and Z=8. In the preparation of complex >3, cleavage of the C=N bond of the Schiff base H₂L² was observed and the ‘2+2+1’ complex >8 [ReO(PPh₃)(η²-NHC₆H₄-2-S)(L)]·CH₂Cl₂ having 2-aminothiophenol as a dianionic bidentate ligand was isolated. Crystals of >8 are monoclinic space group C2/c, a=25.627(2), b=8.1305(6) c=31.404(2) Å β=96.147(1)°, V=6505.7(8) ų, and Z=8. Reduction of HL to 8-hydroxy-5-aminoquinoline was realized during the formation of complex >6, and a new complex >9 was thus isolated involving the coordination of two sets of N,O donor atoms from L and 8-hydroxy-5-aminoquinoline while a methoxy oxygen atom completes the octahedral coordination geometry. Crystals of >9 are monoclinic space group P2₁/n, a=7.5330(6), b=15.095(1), c=16.394(1) Å, β=99.690(2)°, V=1837.7(3) ų, and Z=4.