Preparation and characterization of tricobalt methylidyne clusters: X‐ray crystal structures of [Co 3 (CO) 9 (µ 3 ‐CR)] (R = CH 2 CH 3 , CH 2 C(  O)NH 2 , CH 2 C(  O)CH 3 ) and [Co 3 (CO) 7 (µ‐ P , P ‐PPh 2 CH 2 PPh 2 ) (µ 3 ‐CCH 2 C 6 H 4 NH 2 )]

A small quantity of the tricobalt methylidyne cluster [Co 3 (CO) 9 (µ 3 ‐CCH 2 CH 3 )] ( 2 ) was obtained, along with the major product, [{[Co 2 (CO) 6 (µ‐HCC)]CH 2 NH} 2 CO] ( 1 ), from the reaction of HCCCH 2 NH 2 with Co 2 (CO) 8 in tetrahydrofuran at 45 °C for 5 h. The crystal structure of 2 showed that the amino group was unexpectedly detached from the propargylamine. The reactions of two related amines, HCCC 6 H 4 NH 2 and HCCC(O)NH 2 , with Co 2 (CO) 8 gave two tricobalt methylidyne clusters, [Co 3 (CO) 9 (µ 3 ‐CCH 2 C 6 H 4 NH 2 )] ( 5 ) and [Co 3 (CO) 9 (µ 3 ‐CCH 2 C(O)NH 2 )] ( 7 ), respectively. Further reaction of 5 with bis(diphenylphosphino)methane (DPPM) resulted in the formation of the DPPM‐bridged tricobalt methylidyne cluster [Co 3 (CO) 7 (µ‐ P , P ‐PPh 2 CH 2 PPh 2 )(µ 3 ‐CCH 2 C 6 H 4 NH 2 )] ( 6 ). Similar procedures were followed for the reaction of HCCC(O)CH 3 with Co 2 (CO) 8 ; two compounds, [Co 3 (CO) 9 (µ 3 ‐CCH 2 C(O)CH 3 )] ( 8 ) and [Co 2 (CO) 6 (µ 2 ‐η 2 ‐HCCC(O)CH 3 )] ( 9 ), were obtained. All these compounds were characterized by spectroscopic means; the crystal structures of 2 , 5 , 6 , and 7 were also determined. Copyright © 2003 John Wiley & Sons, Ltd.