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Nickelation of [3‐Et‐7,8‐Ph 2 ‐7,8‐ nido ‐C 2 B 9 H 8 ] 2− : synthesis and characterization of 1,2 → 1,2 and 1,2 → 1,7 isomerized products
Author(s) -
Robertson Susan,
Ellis David,
Rosair Georgina M.,
Welch Alan J.
Publication year - 2003
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.474
Subject(s) - chemistry , isomerization , steric effects , crystallography , stereochemistry , medicinal chemistry , catalysis , organic chemistry
The reaction between [3‐Et‐7,8‐Ph 2 ‐7,8‐ nido ‐C 2 B 9 H 8 ] 2− and Ni(dppe)Cl 2 in tetrahydrofuran affords major and minor products, identified spectroscopically and crystallographically. The major species is 1,2‐Ph 2 ‐4‐dppe‐6‐Et‐4,1,2‐ closo ‐NiC 2 B 9 H 8 , which arises from the presumed initial product 1,2‐Ph 2 ‐3‐dppe‐6‐Et‐3,1,2‐ closo ‐NiC 2 B 9 H 8 by a sterically induced 1,2 → 1,2 C atom isomerization, typical of overcrowded nickelacarboranes. The minor species is 1,8‐Ph 2 ‐2‐dppe‐4‐Et‐2,1,8‐ closo ‐NiC 2 B 9 H 8 , arising from an unexpected 1,2 → 1,7 carbon‐atom isomerization of the initial product. The fact that one boron atom is labelled with an Et group, coupled with the fact that these isomerizations occur at low temperatures, allows comment on the isomerization mechanisms. The minor isomer cannot be explained by reference to Wales' sequential diamond–square–diamond mechanism for 1,2‐ closo ‐C 2 B 10 H 12 → 1,7‐ closo ‐C 2 B 10 H 12 . A simple rationalization of the formation of both major and minor isomers is available through triangle face rotation. Copyright © 2003 John Wiley & Sons, Ltd.