Synthesis of nitrosyl rhenium(I) complexes bearing bidentate ligands

Article abstract of DOI:10.1016/S0022-328X(96)06474-1

The reaction of [ReCl(μ-Cl)(COE)(CO)(NO)]₂ (2) (obtained from [ReCl(μ-Cl)(CO)₂(NO)] and cyclooctene (COE)) with 2,2′-bipyridine and 4,4′-dimethyl-2,2′-bipyridine leads to ReCl₂(CO)L(NO) complexes (L = 2,2′-bipyridine (3), 4,4′-dimethyl-2,2′-bipyridine (4)) with trans chloride substituents. The reaction of [ReCl(μ-Cl)(CO)₂(NO)]₂ (1) with THF produces racemic ReCl₂(CO)₂(THF)(NO) (5). The Re-THF bond in 5 is labile enough to provide a primary coordination site for a bidentate ligand attack. The reaction of 2 with bpy proceeds with regioselective Re-Cl cleavage trans to the CO ligand and affords the ionic [ReCl(CO)₂(bpy)(NO)][ReCl₃(CO)₂(NO)] complex 6 or, when a stoichiometric amount of NaBF₄ is present, [ReCl(CO)₂(bpy)(NO)][BF₄] (7). The reaction of 2 with 1,2-bis(diphenylphosphino)methane (dppm) gives cis,trans-[ReCl₂(η¹-dppm)₂(CO)(NO)] (8) while the transformation with 1,2-bis(diphenylphosphino)ethene (dppee), and NaBF₄, yields an ionic [ReCl(NO)(dppee)₂][BF₄] compound 9. The reaction of racemic trans-1,2-bis(dimethylphosphino)cyclopentane (dmpc) with 5 proceeds with loss of the THF molecule and of one CO group, affording a diastereomeric mixture of ReCl₂(CO)(dmpc)(NO) (10). The compounds 2, 4, 5, 6, 8, 9 and 10 were characterized by X-ray diffraction studies. Crystal data: 2, monoclinic, space group P2₁/c, a = 9.471(5), b = 10.646(6), c = 12.599(7) A, β = 99.78(2)°, V = 1251.8(12) A³, Z =2; 4, monoclinic, space group C₂/m, a = 13.472(4), b = 21.717(7), c = 6.491(2) A, β = 105.33(2)°, V = 1831.7(9) A³, Z = 4; 5, monoclinic, space group P2₁/n, a = 6.114(3), b = 18.443(12), c = 9.954(5) A, β = 96.09(2)°, V = 1116.2(10) A³, Z = 4; 6, triclinic, space group P1, a = 8.894(2), b = 10.376(2), c = 14.660(4) A, α = 97.62(2)°, β = 97.46(2)°, γ = 102.67(2)°, V = 1290.4(6) A³, Z = 2; 8, monoclinic, space group P2₁/n, a = 10.029(3), b = 30.364(9), c = 16.487(3) A, β = 98.10(2)°, V = 4971(2) A³, Z = 4; 9, trigonal, space group P3, a = 20.648(7), c = 11.326(4) A, V = 4182(3) A³, Z = 4; 10, tetragonal, space group Fdd2, a =14.265(3), b = 50.190(10), c = 9.217(2) A, V = 6599(2) A³, Z= 16.