41. Alkyne trimerisation of dimethylacetylene also yields hexamethylbenzene in the presence of a suitable catalyst.42. In some complexes, the alkyne is classified as a four-electron donor. 43. Metal-alkyne complexes are intermediates in the metal-catalyzed trimerization and tetramerizations. 44. The monomers used in this polymerization are oligopeptides with terminal azide and terminal alkyne groups 45. The hydroboration of alkynes gives vinylic boranes which oxidize to the corresponding aldehyde or ketone. 46. They also demonstrate higher reactivity toward alkynes . 47. Disilenes have Si = Si double bonds and disilynes are silicon analogues of an alkyne . 48. "' Phenylacetylene "'is an alkyne hydrocarbon containing a phenyl group. 49. Formal [ 2 + 2 + 2 ] cycloadditions also take place in alkyne trimerisation. 50. *cycloaddition reactions with early example the cycloaddition of an nitrile oxide with an alkyne .