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Transformation of 3,4‐Bis(isopropylidene)‐2,5‐dichloro‐1,2,5‐thiadiborolane into nido ‐2,4,5‐Thiadicarbahexaborane(5) Derivatives – Formation and Computational Elucidation of a Thiadicarbanonaborane(8) with a ni ‐9<IV+IV> Configuration
Author(s) -
Beez Volker,
Greiwe Peter,
Pritzkow Hans,
Hofmann Matthias,
v. R. Schleyer Paul,
Siebert Walter
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199811)1998:11<1775::aid-ejic1775>3.0.co;2-y
Subject(s) - chemistry , hydroboration , yield (engineering) , crystallography , cluster (spacecraft) , ab initio , vertex (graph theory) , stereochemistry , aryl , nuclear magnetic resonance spectroscopy , computational chemistry , organic chemistry , graph , materials science , alkyl , mathematics , discrete mathematics , computer science , metallurgy , programming language , catalysis
The 3,4‐bis(isopropylidene)‐2,5‐dichloro‐1,2,5‐thiadiborolane ( 5b ), obtained from 3,4‐bis(dichloroboryl)‐2,5‐dimethyl‐2,4‐hexadiene ( 4 ) and (Me 3 Si) 2 S, reacts with Li[RBH 3 ] (R = H, C 6 H 5 , C 6 Me 4 H) to yield the corresponding derivatives of the nido ‐4,5‐diisopropyl‐2,4,5‐thiadicarbahexaboranes 2 . Replacements of the chlorine atoms in 5b with two hydrido, or with one hydrido and one aryl (phenyl or duryl) group, followed by the hydroboration of the isopropylidene substituents with RBH 2 (R = H, C 6 H 5 , C 6 Me 4 H) lead to four nido ‐2,4,5‐thiadicarbahexaboranes ( 2a–d ) in low yields. Their composition follows from MS and NMR data; not refined X‐ray structural data of 2d support the proposed skeletal structure. In addition to 2a , larger thiacarboranes were detected by GC/MS and 11 B NMR. The structure of the nine‐vertex cluster 6a could be identified by applying the ab initio/IGLO/NMR method. Geometry optimizations at the MP2(fc)/6–31G* level rule out the C s nido ‐SC 2 B 6 H 8 isomer 7 . The C 2v structure of 6 consists of a nine‐vertex cluster with two elongated B–B distances. As this 22e cluster 6 represents an exception to the Wade rules, the nature of the bonding of nine‐vertex clusters with different electron counts is discussed.