New hydrogen-containing zirconium clusters with phosphine ligands

Article abstract of DOI:10.1016/S0020-1693(96)05466-7

Reaction of ZrCl₄ with 2 equiv. of HSnBu₃ followed by addition of phosphines yields hexazirconium cluster compounds [Zr₆Cl₁₄H₄(PR₃)₄] (2a: PR₃ = PMc₂Ph; 2b: PR₃ = PEt₂Ph; 2c: PR₃ = PEt₃) and pentazirconium cluster compounds [Zr₅Cl₁₂H₄(PR₃)₅] (3a: PR₃ = PMe₂Ph; 3c: PR₃ = PEt₃). Treatment of compound 2a with Na/Hg in the presence of PMe₂Ph results in the formation of [Zr₆Cl₁₂H₂(PMe2Ph)₆] (4a). When the phosphine ligand is PEt₃, a similar reaction leads to the isolation of two new cluster compounds, [Zr₆Cl₁₂H₃(PEt₃)₆] [ZrCl₅(PEt₃)] (5c) and [Zr₆Cl₁₃H₃(PEt₃)₅] (6c). In MeCN solution, compound 2a decomposes to form an ionic cluster compound, [HPMe₂Ph]₄[Zr₆Cl₁₈H⁴] (7a). Cluster hydrogen atoms were observed by ¹H NMR spectroscopy for all cluster compounds and by X-ray diffraction study for compound 3c where two hydrogen atoms are μ₃-bridging and the other two edge-bridging. In compound 7a, there is evidence for the four hydrogen atoms distributed near the centers of the eight triangular faces of the Zr₆ octahedron. When ZrCl₄ reacts with 1 equiv. of HSnBu₃ followed by addition of PR₂Ph, only dinuclear compounds [Zr₂Cl₄(μ-Cl)₂(PR₂Ph) ₄] (8a: R = Me; 8b: R = Et) are isolated. All compounds were characterized by X-ray crystallography and ¹H NMR spectroscopy. Compound 2a · 0.75CH₂Cl₂ crystallized in the monoclinic space group C2/c with cell dimensions (-100°C) of a = 31.434(9), 6=15.255(6), c= 14.582(8) A, β=106.08(2)°, V=6719(9) A3 and Z=4. Compound 2b-2CH₂Cl₂ crystallized in the monoclinic space group P2₁/c with cell dimensions (-60°C) of a= 11.310(1), b= 17.412(5), c= 17.807(2) A, β = 91.55(1)°, V=3505(1) A³ and Z = 2. Compound 2c · 2C₆H₆ crystallized in the monoclinic space group P2₁/n with cell dimensions (-150°C) of a= 15.322(6), b= 12.186(3), c= 16.696(7) A, β = 91.09(2)°, V = 3117(2) A³ and Z = 2. Compound 2c crystallized in the monoclinic space group C2/c with cell dimensions (-150°C) of a = 26.128(9), b = 16.826(1), c= 13.411 (4) A, β = 117.07(1)°, V = 5250(2) A³ and Z=4. Compound 3c · C₆H₅CH₃ crystallized in the monoclinic space group C2/c with cell dimensions (-75°C) of a = 48.06(1), b = 12.667(3), c = 22.829(5) A, β = 113.36(2)°, V= 12758(5) A³ and Z = 8. Compound 4a crystallized in the triclinic space groupa P1 with cell dimensions (-60°C) of a = 12.918(3), b= 15.493(2), c = 18.90(1) A, α = 90.31(6), β = 104.37(2), y= 109.89(3)°, V = 3429(2) A³ and Z = 2. Compound 5c · 0.5C₆H₆ crystallized in the monoclinic space group P2/c with cell dimensions (-60°C) of a = 23.707(6), b = 14.521(2), c = 25.109(3) A β = 92.08(1)°, V=8633(3) A³ and Z = 4. Compound 6c · C₆H₆ crystallized in the orthorhombic space group Pna2₁ with cell dimensions (-100°C) of a = 23.496(9), b = 23.973(2), c= 11.638(1) A, V = 6555(3) A³ and Z = 4. Compound 7a · 2MeCN crystallized in the triclinic space group P1 with cell dimensions (20°C) of a = 12.881(2), b = 22.859(3), c =12.208(2) A, α = 98.66(1), γ = 109.99(1), 7=81.39(1)°, V =3320.8(9) A³ and Z = 2. Compound 8b-0.67C₆H₅CH₃ crystallized in the rhombohedral space group R3m with cell dimensions (-100°C) of a = 20.947(3), b = 20.947(3), c = 30.87(1) A, V = 11730(4) A³ and Z = 6.