Issue 11, 2002

The first silyl- and germylboryl complexes: synthesis from novel (dichloro)silyl- and (dichloro)germylboranes, structure and reactivity

Abstract

A series of silyl- and germyl(dichloro)boranes Cl2B–ER3 (5, ER3 = Si(SiMe3)3; 6, ER3 = Ge(SiMe3)3; 7, ER3 = Si(SiMe3)2–Si(SiMe3)3; 8, ER3 = SiPh3) was obtained in good yields from the corresponding bis(dimethylamino)boranes (Me2N)2B–ER3 (1, ER3 = Si(SiMe3)3; 2, ER3 = Ge(SiMe3)3; 3, ER3 = Si(SiMe3)2–Si(SiMe3)3; 4, ER3 = SiPh3) upon reaction with BCl3, and fully characterised in solution. These compounds proved to be versatile starting materials for the synthesis of the first silyl- and germylboryl complexes by salt elimination reactions starting from anionic transition metal complexes of the type Na[(η5-C5R5)Fe(CO)2] and K[(η5-C5R5)Mn(H)(CO)2]. The novel iron and manganese boryl complexes [(η5-C5R4R′)(OC)2Fe–B(Cl)Si(SiMe3)3] (9a, R = R′ = H; 9b, R = H, R′ = Me; 9c, R = R′ = Me), [(η5-C5H5)(OC)2Fe–B(Cl)Ge(SiMe3)3] (9d), [(η5-C5H5)(OC)2Fe–B(Cl)Si(SiMe3)2Si(SiMe3)3] (9e), [(η5-C5H4Me)(OC)2(H)Mn–B(Cl)Si(SiMe3)3] (10a) and [(η5-C5H4Me)(OC)2(H)Mn–B(Cl)Ge(SiMe3)3] (10b) were obtained in yields between 35 and 70%, fully characterised in solution and in the case of 9a, d, and 10a also in the crystalline state. They are all characterised by metal–boron σ-bonds without indication of any metal-to-boron π-backdonation. There is, however, spectroscopical and structural evidence for the presence of a Mn–H–B bridge in the case of the manganese complexes 10a, b. The first transhalogenation of a metal coordinated boryl ligand was achieved by reaction of 9a with TlF affording the fluoroboryl complex [(η5-C5H5)(OC)2Fe–B(F)Si(SiMe3)3] (11), which was characterised in solution and in the solid state.

Graphical abstract: The first silyl- and germylboryl complexes: synthesis from novel (dichloro)silyl- and (dichloro)germylboranes, structure and reactivity

Supplementary files

Article information

Article type
Paper
Submitted
29 yan 2002
Accepted
19 mar 2002
First published
30 apr 2002

J. Chem. Soc., Dalton Trans., 2002, 2289-2296

The first silyl- and germylboryl complexes: synthesis from novel (dichloro)silyl- and (dichloro)germylboranes, structure and reactivity

H. Braunschweig, M. Colling, C. Kollann and U. Englert, J. Chem. Soc., Dalton Trans., 2002, 2289 DOI: 10.1039/B201100J

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