Alkinol- und alkindiol-funktionalisierte zirconocen-verbindungen: Synthese, struktur und reaktionsverhalten 1

Article abstract of DOI:10.1016/S0022-328X(96)06402-9

The reaction of [Zr]Cl₂ (1) {[Zr] = (η⁵-C₅H₄SiMe₃)₂Zr} with HO(CR₂)_nC≡CH (2a: R = H, n = 2; 2b: R = H, n = 4; 2c: R = CH₃, n = 1) or HOCH₂C≡CCH₂OH (2d) yields, depending on the nature of the bases used [1,4-diazabicyclo[2.2.2]octane (DABCO) or NEt₃], different substitution products. On treatment of 1 with 2a or 2b in toluene in the presence of DABCO, the σ-alkynol-substituted zirconocenechlorides [Zr](Cl)[O(CH₂)_nC≡CH] (3a: n = 2; 3b: n = 4) are formed. Moreover, zirconocene σ-dialkynols [Zr][O(CR₂)_nC≡CH]₂ (4a: R = H, n = 2; 4b: R = H, n = 4; 4c: R = CH₃, n = 1) can be obtained by treatment of compounds 1, 3a or 3b with 2a-2c in NEt₃. When 2d is reacted with two equivalents of 1 in the presence of DABCO, the product isolated is (Cl)[Zr](μ,-OCH₂C≡CCH₂O)[Zr](Cl) (5), while in NEt₃ as solvent cyclic [Zr] (μ-OCH₂C≡CCH₂O)₂[Zr] (6) is obtained. The chemical behaviour of compounds 3 and 4 is discussed. The reaction of [Zr](Cl)[O(CH₂)₂C≡CH] (3a) with [CuO₂CMe]₄ (7) yields [Zr](Cl)(μ,-O₂CMe) (8) by elimination of [CuO(CH₂)₂C≡CH]_n. Treatment of compounds 3a, 4a or 4c with Co₂(CO)₈ (9) affords [Zr](Cl){[η₂-O(CH₂)₂C≡CH] Co₂(CO)₆} (10), [Zr]{[η₂-O(CH₂)₂C≡CH] Co₂(CO)₆}₂ (11a) or [Zr]{[η₂-OCMe₂C≡CH]Co₂(CO)₆}₂ (11b) respectively. In each of these compounds the HC≡C building block is η²-coordinated to a Co₂(CO)₆ fragment. Treatment of complexes 3a, 4b, 10 or 11 with HCl_(aq) produces [Zr]Cl₂ (1) and 2a or 2b [reaction of 3 or 4 with HCl_(aq)] or [Zr]Cl₂ (1) and [η₂-HO(CH₂)₂C≡CH]Co₂(CO)₆ (12a) or (η²-HOCMe₂C≡CH)Co₂(CO)₆ (12b) [reaction of 10 or 11 with HCl_(aq)]. The solid state structures of compounds [Zr](Cl)[O(CH₂)₂C≡CH] (3a), (Cl)[Zr](μ-OCH₂C≡CCH₂O)[Zr](Cl) (5) and [Zr]{[η₂-OCMe₂C≡CH]Co₂(CO)₆}₂ (11b) are reported. 3a crystallizes in the rhombic space group Pnma with cell constants a = 813.1(3), b = 1523.7(5), c = 1850.0(6) pm, V = 2292.0(9) × 10⁶ pm³ and Z = 4. Crystals of 5 and 11b are monoclinic. Compound 5: space group Pc with a = 1290.8(6), b - 2582(1), c - 760.1(3) pm, β = 73.15(3)°, V = 2424(2) × 10⁶ pm³ and Z = 2. Compound 11b: space group P2₁/n with a = 1461.0(6), b = 2057(1), c = 1528.4(6) pm, β= 96.06(3)°, V = 4567(3) × 10⁶ pm³ and Z = 4.