114995-23-2Relevant academic research and scientific papers
Synthesis and reactivity of heterobimetallic a-frames and Rh-Zr bonded complexes: Structure of Cp*Zr(μ-OCH2Ph2P)2RhMe2
Ferguson, Gregory S.,Wolczanski, Peter T.,Párkányi, László,Zonnevylle, Marjanne C.
, p. 1967 - 1979 (2008/10/08)
The preparations of Rh/Zr A-frame and metal-metal bonded complexes are detailed. Treatment of Cp*MeZr(OCH2Ph2P)2 (2, Cp* = η5-C5Me5), prepared from Cp*ZrMe3 (1) and 2.0HOCH2Ph2P, with 0.5[(OC)2RhCl]2 (3) afforded Cp*Zr(μ-OCH2Ph2P)2(μ 2-η2-O=C(CH3))(μ-Cl)RhCO (4). The μ2-η2-acetyl bridge was cleaved from 4 by HCl to yield acetaldehyde (61%) and Cp*Zr(μ-OCH2Ph2P)2(μ-Cl) 2RhCO (5, 68%), more conveniently isolable from refluxing 4 in CHCl3. 1H NMR and IR evidence for an acetyl-hydride intermediate, [Cp*Zr(μ-OCH2Ph2P)2(μ 2-η2-O=C(CH3))(μ-Cl)Rh(CO)H]Cl ([4H]Cl), was obtained. Acetone (93%) and Cp*Zr(μ-OCH2Ph2P) 2(μ-Cl)(μ-I)RhCO (7, 85%) are formed from exposure of 4 to MeI. The reaction of (Ph3P)3RhMe (8a) with 2 provided Cp*Zr(μ-OCH2Ph2P)2RhMe2 (9), which contains a short 2.444 (1) A? Rh-Zr bond generated via the oxidative addition of a ZrMe group to Rh. Crystal data: triclinic, P1, a = 11.734 (1) A?, b = 10.524 (1) A?, c = 15.266 (1) A?, α = 104.15 (1)°, β = 93.92 (2)°, and γ = 112.90 (2)°, Z = 2, T = 25°C, R = 0.063, Rw = 0.051 (2717 (60.2%) reflections where |Fo| ≥ 3σ(Fo)). Byproduct Cp*Zr(μ-OCH2Ph2P)3RhMe (11) was best synthesized through the addition of Cp*Zr(OCH2Ph2P)3 (10) to 8a. Through a similar pathway, (Ph3P)3RhH (8b) and 2 yielded Cp*Zr(μ-OCH2Ph2P)2RhPPh3 (12) concomitant with 0.96CH4. Hydrogenation of 12 or 9 (-1.9CH4) produced Cp*Zr(μ-OCH2Ph2P)2RhH 2-(PPh3) (13). The latter hydrogenated C2H4 to give ethane and 12 or Cp*Zr(μ-OCH2Ph2P)2Rh(η 2-C2H4) (14), if excess was used. The reversible binding of PPh3 to 13 and 14 was evidenced. Extended Hu?ckel calculations performed on a model of 9 revealed that the Rh-Zr interaction is 47% σ and 53% π in character, providing a strong indication of multiple bonding. Alternatively, 9 may be considered a donor/acceptor complex with Zr acting as a σ- and π-acceptor Lewis acid. The results were compared with calculations addressing similar M-M′ bonded systems. The relationship of the compounds above to heterogeneous oxygenate-selective F-T catalysts and strong metal-support interactions (SMSI) is also discussed.
