OPEN AND HALF-OPEN RUTHENOCENES AND OSMOCENES - PROTONATIONS, STRUCTURES, AND REACTIONS WITH CARBONYL AND PHOSPHINE-LIGANDS

The synthesis of a protonated “open ruthenocene”, “HRu(2,4-C7H11)2+BF4-”, is reported, as well as its osmium analogue. The addition of 1 equiv of CO or P(OMe)3 leads to the formation of mono(ligand) adducts, during which one of the pentadienyl ligands and the hydride ligand combine to yield an η4-2,4-di-methylpentadiene complex, in accord with the formulation of “HRu(2,4-C7H11)2+” as an agostic species. The addition of 2 equiv of a second ligand to the monoadducts then brings about the removal of the diene ligand, allowing isolation of Ru(2,4-C7H11)(CO)2(PEt3)+ and Ru(2,4-C7H11)(CO)(PEt3)2+, as well as symmetric complexes such as Ru(2,4-C7H11)(L)3+ (L = CO, P(OMe)3, PMe3). X-ray diffraction studies are reported for several of these compounds. Crystals of Os(C5H5)(2,4-C7H11) are isomorphous with the iron and ruthenium analogues, being orthorhombic, space group Pnma (No. 62), with a = 5.900 (2) Å, b = 13.089 (7) Å, c = 13.503 (6) Å, and Z = 4. The structure was refined to discrepancy indices of R = 0.043 and RW = 0.044 for 1170 reflections having I > 2.5σ(7) and revealed similar Os-C distances for the open and closed dienyl ligands. Crystals of Ru(2,4-C7H11)(η4-2,4-C7H12)(CO)+BF4- are monoclinic, space group Ρ21/n (No. 14), with a = 8.436 (6) Å, b = 13.818 (4) Å, c = 15.199 (9) Å, β = 104.72 (5)°, and Z = 4. The structure was refined to discrepancy indices of R = 0.053 and Rw = 0.046 for 2337 reflections having I > 2.5σ(I). The general structure involves the diene and dienyl fragments having their open edges essentially eclipsed, with the carbonyl ligand being situated between these open edges. Crystals of Ru(2,4-C7H11)(CO)2(PEt3)+BF4- are monoclinic, space group P21/m (No. 11), with a = 8.863 (2) Å, b = 12.246 (2) Å, c = 9.801 (2) Å, β = 112.98 (2)°, and Z = 2. The structure was refined to discrepancy indices of R = 0.037 and Rw = 0.032 for 2337 reflections having I > 2.5σ(I). The structure may be regarded as symmetric, with the phosphine ligand located under the open edge of the dienyl ligand and the two carbonyl ligands located under the formally uncharged pentadienyl carbon atoms in the 2- and 4-positions. The carbonyl ligands are crystallographically equivalent, being related to one another by a mirror plane that bisects the dienyl and phosphine ligands. Crystals of Ru(2,4-C7H11)(CO)(PEt3)2+BF4-, as an apparent ethanol solvate, are monoclinic, space group P21/n (No. 14), with a = 10.809 (3) Å, b = 27.134 (7) Å, c = 10.879 (3) Å, β = 115.40 (2)°, and Z = 4. The structure was refined to discrepancy indices of R = 0.067 and Rw = 0.054 for 1578 reflections having I > 2.5σ(I). This structure may be regarded as unsymmetric, being related to the previous one by replacement of one carbonyl ligand under a formally uncharged carbon atom by the second PEt3 molecule. © 1990, American Chemical Society. All rights reserved.