Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 2. Formation of manganese–platinum, –palladium, and –nickel compounds, and the crystal structures of two forms of [(OC)4Mn{µ-(1-σ,1–2-η-CCH–CH2–CH2–O)}Pt(PMe3)2]

Abstract

The mononuclear manganese–carbene complex [Mn{C(OMe)Ph}(η-C₅H₅)(CO)₂] reacts with the compound [Pt(cod)₂](cod = cyclo-octa-1,5-diene) to give the dimetal complex [(OC)₂(η-C₅H₅)[graphic omitted]t(cod)]. Similarly, [Pt(C₂H₄)₃], [Pd(dba)₂](dba = dibenzylideneacetone), and [Ni(cod)₂], each treated with 2 mol of PMe₃, react with the mononuclear manganese compound to yield heteronuclear dimetal complexes [(OC)₂(η-C₅H₅)[graphic omitted](PMe₃)₂](M = Ni, Pd, or Pt). The PMe₃ ligand trans to the µ-C(OMe)Ph group in the palladium and platinum compounds is readily replaced by CNBu^t. The binuclear manganese–carbene complex [(OC)₅Mn–Mn([graphic omitted])(CO)₄] reacts with [Pt(C₂H₄)₃], treated with 2 mol of PMe₃, to form two crystalline forms of a compound [(OC)₄[graphic omitted]t(PMe₃)₂]. Single-crystal X-ray diffraction studies have been carried out (200 K) on these geometrical isomers. The red form is monoclinic, space group P2₁/n, Z= 4, in a unit cell with lattice parameters a= 9.357(5), b= 12.844(10), c= 15.989(9)Å, and β= 98.14(4)°. The structure has been refined to R 0.023 (R′ 0.030) for 3 274 reflections to 2θ⩽ 50°(Mo-K_αX-radiation). The yellow form is triclinic, space group P, Z= 2, in a unit cell with lattice parameters a= 9.429(5), b= 12.113(4), c= 9.729(6)Å, α= 93.97(14), β= 115.45(4), and γ= 98.83(3)°. The structure has been refined to R 0.055 (R′ 0.073) for 3 350 reflections to 2θ⩽ 50°(Mo-K_αX-radiation). In both isomers a cyclic 1-σ,1–2-η-[graphic omitted] ligand bridges a platinum–manganese bond such that the manganese atom is η²-co-ordinated by the CCH group, which is σ-bonded to the platinum. The two forms differ in the relative orientation of some least-squares planes involving various groups of atoms comprising the molecules and in the Mn–Pt distances [2.6909(7)Å red form, 2.659(2)Å yellow form]. The ¹H, ¹³C, and ³¹P n.m.r. spectra of the various compounds are discussed.