RADIATION ENHANCEMENT OF THE CATALYTIC PROPERTIES OF 3-DIMENSIONAL COORDINATION POLYMERS OF RU(II) WITH DIISOCYANIDE LIGANDS

Coordination polymers are drawing increasing attention due to their ve rsatility in structure and function, and their potential applications as catalysts. These polymers may be synthesized by using aryldiisocyan ides, which when coordinated to a d(6) metal such as Ru(II), act as br idges and give rise to two distinct types of three-dimensional polymer ic networks. Polymer A, [Ru(1,4-diisocyanobenzene)(4/2)(2+)(2Cl)(2-)]( n) has a tetragonal geometry having, most likely, Ru-Ru stacking inter actions in the z direction, while polymer B, [Ru(1,4-diisocyanobenzene )(6/2)(2+)(2Cl)(2-)](n) has a cubic geometry, having all the Ru atoms separated by the 1,4-diisocyanobenzene ligands, In the hydrogenation r eaction of 1-hexene, polymer A is an efficient but a non-selective cat alyst, The hydrogenation reaction is accompanied by isomerization, wit h trans 2-hexene as the leading isomer, which is hydrogenated as well after all the 1-hexene has been used up, The catalytic reaction procee ds with an induction period which suggests that polymer A in its origi nal structure is not the actual catalyst. Irradiation of the reaction mixture with 350 nm UV light prior and during the catalytic reaction d rastically reduces the induction period, This indicates that the energ y of irradiation is sufficient to break the Ru-Ru stacking bonds, thus creating electron-deficient Ru sites prior to the addition of the ole fin. An in-depth study of the influence of irradiation on the kinetics of the catalytic reaction is presented in this paper.