Reactions of (η⁵-C₅Me₅)ZrF₃, (η⁵-C₅Me₄Et)ZrF₃, (η⁵-C₅Me₅)₂ZrF₂, (η⁵-C₅Me₅)HfF₃, and (η⁵-C₅Me₅)TaF₄ with AlMe₃. Structure of the First Hafnium−Aluminum−Carbon Cluster

Abstract

The reaction of Cp*ZrF 3 (1) (Cp* ) η 5 -C 5 Me 5 ) and AlMe 3 resulted in the formation of cis-{[Cp*ZrMe(µ 2 -F)][(µ 2 -F) 2 AlMe 2 ]} 2 (6) and [(Cp*Zr) 3 Al 6 Me 8 (µ 3 -CH 2 ) 2 (µ 4 -CH) 4 (µ 3 -CH)] ( 7), respectively. Analogously, (η 5 -C 5 Me 4 Et)ZrF 3 (3) reacts with AlMe 3 in a molar ratio of 1:5 with methane elimination to give the Zr 3 Al 6 C 7 cluster of composition {[(η 5 -C 5 Me 4 Et)Zr] 3 Al 6 Me 8 -(µ 3 -CH 2 ) 2 (µ 4 -CH) 4 (µ 3 -CH)} ( 8), which has been characterized by elemental analysis and 1 H NMR and mass spectrometry. Reaction of 2 equiv of AlMe 3 with Cp* 2 ZrF 2 (2) leads quantitatively to Cp* 2 ZrMe 2 (12). Reaction of Cp*HfF 3 (4) with AlMe 3 in an equimolar ratio gives {[Cp*HfMe (µ 2 -F)][(µ 2 -F) 2 AlMe 2 ]} 2 (9) stereospecifically as its cis isomer in high yield. 9 crystallizes in the space group P2 1 /c with four molecules in the elemental cell (Z ) 16). From the reaction of 1 equiv of Cp*HfF 3 (4) with 3 equiv of AlMe 3 , Cp*HfMe 3 (10) can be obtained in a yield of 85%. As a byproduct of this reaction the Hf 3 Al 6 C 7 cluster [(Cp*Hf) 3 -Al 6 Me 8 (µ 3 -CH 2 ) 2 (µ 4 -CH) 4 (µ 3 -CH)] ( 11) can be isolated in a yield of 5%. The characterization of 11 by single-crystal X-ray diffraction and 1 H, 13 C NMR and mass spectroscopic data will be discussed. Cp*TaF 4 (5) reacts with a 5-fold excess of AlMe 3 , leading quantitatively to Cp*TaMe 4 (13) without further decomposition via C-H activation processes.

Reactions of the titanium-carbide species CpTi(μ2-Me)(μ2-NPi-Pr3)(μ4-C)(AlMe2)3

“…Additionally, we have published the mechanistic details of the divergent C-H activation pathways observed in the reaction of (t-Bu 3 PN) 2 TiMe 2 with AlMe 3 , which affords [(l 2 -tBu 3 PN)Ti(l-Me)(l 4 -C)(AlMe 2 ) 2 ] 2 (c) and (t-Bu 3 PN)Ti-(l 2 -t-Bu 3 PN)(l 3 -CH 2 ) 2 (AlMe 2 ) 2 (AlMe 3 ) (d) [29]. Related C-H activations in the formation of the Zr and Hf clusters, (Cp * M) 3 Al 6 Me 8 (l 3 -CH 2 ) 2 (l 4 -CH) 4 (l 3 -CH) (M = Zr, Hf) have also been previously described by Roesky et al [30,31]. Much of this chemistry is reminiscent of the C-H bond activation in the formation of the well-known Tebbe reagent, Cp 2 Ti(l-CH 2 )(l-Cl)AlMe 2 [32].…”

A Tetranuclear Planar Hafnium Complex Containing O–Hf–S Moieties

“…While the Hf-Cl cluster chemistry [6] is relatively well known and Hf-F-based di-and trinuclear complexes have been isolated by Roesky et al, [7] there are few examples of which the metal atoms are μ 3 -O bridged and the thioacetate ligands coordinate the Hf ions both through a bridging and a chelating mode. The structural findings are confirmed by multinuclear NMR spectroscopic data.…”

Polymerization of styrene with supported half-sandwich complexes

“…Half-sandwich complexes are also known to form clusters by condensation reactions. 30 The formation of these inactive structures requires bimetallic reactions. Therefore, supporting metallocene catalysts on a carrier should effectively reduce this particular condensation reaction, as has been shown for supported zirconocenes.…”