摘要:
Reduction of [ReO2(en)2]+, [ReO2(NH3)4]+, or [ReO2(ampy)2]+ (en =ethylenediamine;ampy = 2-(aminomethyl)-pyridine) in HCl (aq) produces [ReCl2(en)2]+, [ReCl2(NH3)4]+, and [ReCl2(aMPY)2]+ respectively. Chloride substitution on trans-[ReCl2(en)2]+ by pyridine, isonicotinamide, nicotinamide, 4-picoline, 4-(dimethylamino)-pyridine, and n-propylamine is accomplished with accompanying isomerization to a cis geometry. The crystal structures of [ReCl2(en)2](PF6) (triclinic; P1BAR (No. 2); a = 8.717(1) angstrom, b = 12.618(2) angstrom, c = 6.523(1) angstrom, alpha = 98.44(2)-degrees, beta = 102.66(1)-degrees, gamma = 78.50(1)-degrees; D(calcd) = 2.543 g/cm3;Z = 2), [ReCl2(ampy)2](BPh4),(triclinic; P1BAR (No. 2); a = 12.334(1) angstrom, b = 17.345(2) angstrom, c = 8.918(1) angstrom, alpha = 91.30(3)-degrees, beta = 94.75(3)-degrees, gamma = 73.29(2)-degrees; D(calcd) = 1.551 g/cm3; Z = 2), and [ReCl(picoline)(en)2] (PF6)2, (monoclinic; P2(1)/c (No. 14); a = 9.233(3) angstrom, b = 17.824(5) angstrom, c = 13.979(5) angstrom, beta = 108.15(3)-degrees; D(calcd) = 2.202 g/cm3; Z = 4) are reported, and various equilibrium constants are determined which pertain to the relative affinity of Re(II) and of Re(III) for pi-acid ligands. Parallels are drawn to the established pi-bases [Ru(NH3)5]2+ and [Os(NH3)5]2+.