Constructing a short C–H · · · O hydrogen bond: the crystalline complex of triphenylsilylacetylene with triphenylphosphineoxide. A very unusual crystal structure with Z = 7 and Z′ = 3.5
- 1 January 1997
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 7,p. 1287-1292
- https://doi.org/10.1039/a700072c
Abstract
The crystalline complex of triphenylsilylacetylene (Ph3Si–CC–H) and triphenylphosphineoxide (Ph3PO) contains four symmetry independent molecular dimers which are connected by CC–H · · · OP hydrogen bonds. These hydrogen bond have H · · · O separations between 1.99 and 2.05 Å, and are the shortest reported for acetylenic donors. This reflects the fact that the hydrogen bonds are formed between one of the strongest known C–H donors and one of the strongest O acceptors. The red-shift of the acetylenic IR C–H stretching vibration compared to an apolar solution is -149 cm-1, the largest reported for a known crystal structure. The crystal packing in space group P is complex with the very rare unit cell content of 3.5 formula units per asymmetric crystal unit (Z′ = 3.5).Keywords
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