Ungewöhnliche Verbrückung der Metallzentren im dimeren Bis(η‐methylcyclopentadienyl)‐phenylethinylzirconium

Abstract

I Diese Arbeit wurde vom Fonds der Chemischen lndustrie gefordert 456 0 V C H Verlagsgesell.whafi mbH. 0-6940 Weinheim. 1986 0044-8249/86/0505-0456 0 02.50/0 Angew. Chem. 98 (1986) Nr. 5 Soc. 93 (1971) 7201; c) Versuche zur experimentellen Realisierung bei rein organischen Systemen siehe z. B.: C. Schnieders, H.4. Altenbach. Engl. 20 (1981) 93; d) siehe auch: D. Cremer, E. Kraka. 1. Am. Chern. Soc. 107 (1985) 3800; D. B. Brown: Mixed-Valence Compounds. D. Reidel. Dordrecht 1980. Angew. Chem. 98 (1986) Nr. 5 0 V C H Verlagsgesellschaff mbH. 0-6940 Weinheim. 1986 0044-8249/86/0505-0457 S 02.50/0

Synthesis and Characterization of Multiferrocenyl‐Substituted Group 4 Metallocene Complexes

“…The last might be explained by the resonance structures 6 a and 6 a' in the possible mesomeric formulas (Scheme 8). [16] However, the bond-stretching frequency of the CC triple bond in the infrared spectrum at ñ = 1805 cm À1 is in the expected region of s,p-alkynyl-bridged complexes similar to 6. [17] The molecular structures of a few dimeric Group 4 acetylide complexes of type [Cp' 2 M(m-h 1 :h 2 -C < = 3 > CR)(m-Scheme 6.…”

“…The acetylide group deviates from linearity, shown by a Zr1‐C2‐C1 angle of 173.5(2)° and a C2‐C1‐C13 angle of 151.4(2)°. The last might be explained by the resonance structures 6 a and 6 a ′ in the possible mesomeric formulas (Scheme ) 16. However, the bond‐stretching frequency of the CC triple bond in the infrared spectrum at $\tilde \nu $ =1805 cm −1 is in the expected region of σ,π‐alkynyl‐bridged complexes similar to 6 17…”

“…[14] h 1 :h 2 -CCR')MCp' 2 ] were described in the last years (M = Ti, Zr). [16,17] Thereby, Cp' represents substituted or unsubstituted cyclopentadienyl units and the substituents R and R' are alkyl, aryl, SiMe 3 , or SnMe 3 groups. The important bond lengths and angles of the symmetric zirconium complexes are similar to 6.…”

“…The molecular structures of a few dimeric Group 4 acetylide complexes of type [Cp′ 2 M(μ‐η 1 :η 2 ‐C<=3>CR)(μ‐η 1 :η 2 ‐CCR′)MCp′ 2 ] were described in the last years (M=Ti, Zr) 16. 17 Thereby, Cp′ represents substituted or unsubstituted cyclopentadienyl units and the substituents R and R′ are alkyl, aryl, SiMe 3 , or SnMe 3 groups.…”

Single‐Electron Oxidation of Tungsten Acetylide Complexes [(η5‐C5H5)(CO)(NO)W–C≡C–R]Li

“…The W(1)–C(6) bond length (2.025 Å) is shorter than those reported for the σ‐acetylide complexes [(η 5 ‐C 5 H 5 )(η 3 ‐crotyl)(NO)W–C≡C–Ph] (2.104 Å)7f and [(η 5 ‐C 5 H 5 )WRe(μ‐I)(C≡C–Ph)(CO) 5 ] (2.09 Å) 13. The C α –C β bond length (1.250 Å) is comparable to those reported for {[(η 5 ‐C 5 H 5 )μ‐(CO)(NO)W][(η 5 ‐C 5 H 5 )(CO)Fe–C≡C–Ph]} (1.25 Å),8 [{(H 3 CCp) 2 Zr} 2 (μ‐C≡C–Ph) 2 ] (1.261 Å),5a and [Cp 2 Zr(μ‐C≡C–SiMe 3 )(μ‐C≡C–Ph)ZrCp 2 ] (1.267 Å),5b butelongated compared to non‐coordinated C≡C bonds (H–C≡C–H: 1.21 Å; H–C≡C–CH 3 : 1.207 Å)14 and σ‐acetylide complexes (1.206–1.21 Å) 7f,5a. The tungsten–tungsten distance, with 3.0389 Å, is slightly shorter than the tungsten–tungsten single bond in [{(OC) 5 W} 2 C=C=CPh 2 ] (3.15 Å) 15…”