The chemical reactivity of phosphorus-bridging carbonyl compounds: a novel approach to homogeneous catalysis?

The use of a bicyclic metal carbonyl matrix allows the stabilization of phosphorus-bridging carbonyl groups in air-stable, readily synthesized iron carbonyl derivatives of the general type (R2NP)(2)COFe2(CO)(6) (R2N=bulky dialkylamino group, particularly iPr(2)N). Such phosphorus-bridging carbonyl derivatives readily undergo extrusion of the phosphorus-bridging carbonyl group at similar to 100 degrees C to give a (R2NP)(2)Fe-2(CO)(6) unit with reactive sites on the phosphorus atoms which can be trapped by a variety of reagents. For example, alcohols trap (iPr(2)NP)(2)Fe-2(CO)(6) as (ROPN-iPr(2))(iPr(2)NPH)Fe-2(CO)(6) whereas the (iPr(2)NP)(2)Fe-2(CO)(6) unit can also add to the C=N of acetonitrile or benzonitrile, the C=O of aldehydes, ketones, or even maleic anhydride, and the C=C of acrylonitrile. The phosphorus-bridging carbonyl extrusion chemistry of (iPr(2)NP)(2)COFe2(CO)(6) suggests the possibility of designing novel synergistic catalyst systems in which reactive vacant sites are generated at phosphorus atoms adjacent to vacant sites on transition metal atoms. (C) 1998 Elsevier Science S.A. All rights reserved.