International conference on radioisotopes in scientific research: (Paris, 9–20 September 1957)

Abstract

The following ansa-ligand precursors, Et(H)Si(C5H5)2 (1), Et(H)Si(C5HMe4)Cl (2), Et(H)Si(C5HMe4)(C5H5) (3), Ph(H)Si(C5HMe4)Cl (4), Ph(H)Si(C5HMe4)(C5H5) (5), Ph(H)Si(C5HMe4)2 (6), CH2CHCH2(H)Si(C5HMe4)Cl (7), CH2CHCH2(H)Si(C5HMe4)(C5H5) (8), CH2CHCH2(H)Si(C5HMe4)2 (9), and their lithium derivatives, Li2{Et(H)Si(C5H4)2} (10), Li2{Et(H)Si(C5Me4)(C5H4)} (11), Li2{Ph(H)Si(C5Me4)(C5H4)} (12), Li2{Ph(H)Si(C5Me4)2} (13), Li2{CH2CHCH2(H)Si(C5Me4)(C5H4)} (14) and Li2{CH2CHCH2(H)Si(C5Me4)2} (15) have been prepared. The group 4 metal complexes, [M{Et(H)Si(η5-C5H4)2}Cl2] (M = Ti (16a), Zr (16b), Hf (16c)), [M{Et(H)Si(η5-C5Me4)(η5-C5H4)}Cl2] (M = Ti (17a), Zr (17b), Hf (17c)), [M{Ph(H)Si(η5-C5Me4)(η5-C5H4)}Cl2] (M = Ti (18a), Zr (18b), Hf (18c)), [M{Ph(H)Si(η5-C5Me4)2}Cl2] (M = Ti(19a), Zr (19b), Hf (19c)), M{CH2CHCH2(H)Si(η5-C5Me4)(η5-C5H4)}Cl2] (M = Ti (20a), Zr (20b)) and [M{CH2CHCH2(H)Si(η5-C5Me4)2}Cl2] (M = Ti (21a), Zr (21b), Hf (21c)) were synthesized from the reaction of the lithium ansa-derivatives and the tetrachloride salts of the transition metal. The reactivity of the group 4 metal complexes in hydrosilylation processes has been studied. The reaction of 16b, 17a and 17b with tetravinylsilane gave [Zr{(CH2CH)3SiCH2CH2(Et)Si(η5-C5H4)2}Cl2] (22b) and [M{(CH2CH)3SiCH2CH2(Et)Si(η5-C5Me4)(η5-C5H4)}Cl2] (M = Ti (23a), Zr (23b)), respectively. The reaction of 17a and 17b with dimethyldivinylsilane yielded the hydrosilylation products [M{(CH2CH)Me2SiCH2CH2(Et)Si(η5-C5Me4)(η5-C5H4)}Cl2] (M = Ti (24a), Zr (24b)), respectively. 23b and 24b reacted with the silane reagent HSiEt3 to form, via hydrosilylation, [Zr{(Et3SiCH2CH2)3SiCH2CH2(Et)Si(η5-C5Me4)(η5-C5H4)}Cl2] (25b) and [Zr{(Et3SiCH2CH2)Me2SiCH2CH2(Et)Si(η5-C5Me4)(η5-C5H4)}Cl2] (26b), respectively.The previously synthesized compounds, [M{CH2CH(Me)Si(η5-C5Me4)2}Cl2] (M = Ti (27a), Zr (27b)) and [Zr{CH2CHCH2(Me)Si(η5-C5Me4)2}Cl2] (28b), have also been tested in reactions of hydrosilylation with SiHMeCl2 to give [M{Cl2MeSiCH2CH2(Me)Si(η5- C5Me4)2}Cl2] (M = Ti (29a), Zr (29b)) and [Zr{Cl2MeSiCH2CH2CH2(Me)Si(η5-C5Me4)2}Cl2] (30b). All the zirconocene compounds are active to varying degrees as catalysts in the polymerization of ethylene. The molecular structures of 21b and 21c have been determined by single crystal X-ray diffraction studies.