Acetonitrile exchange reactions of 2-RC2R)2> (R = Me or Ph) and (η2-MeC2Me)> with thiophene-3-acetonitrile. X-Ray crystal structure of (η2-MeC2Me)2>

Article abstract of DOI:10.1016/0022-328X(91)86146-H

The complexes 2-RC2R)2> (R = Me or Ph) and 2-MeC2Me)> react with equimolar quantities of thiophene-3-acetonitrile (NCCH2(3-C4H3S)) in dichloromethane at room temperature to give the acetonitrile-exchanged products (η²-RC2R)2> (1 and 2) and (η²-MeC2Me)> (3) respectively in good yields.The crystal structure of (η²-MeC2Me)2> (1) was determined.The coordination geometry about the tungsten may be regarded as octahedral, with the but-2-yne ligands parallel to each other and trans to the iodide ligands.The carbon monoxide and thiophene-3-acetonitrile ligands are mutually trans to each other. 13C NMR spectroscopy indicates that the alkyne ligands in 1 are donating a total of six electrons to the tungsten, whereas the but-2-yne ligand in 3 is donating four electrons to the tungsten.The barrier to but-2-yne rotation of 3 was calculated to be 51.3 kJ mol^-1.