Photocatalytic properties of new cyclopentadienyl and indenyl rhodium(I) carbonyl complexes with water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) and tris(2-cyanoethyl)phosphine

Reactions of (η⁵-R)Rh(CO)₂] (R = cp, ind) with water-soluble phosphines (L = 1,3,5-triaza-7-phosphaadamantane and tris(2-cyanoethyl)phosphine) give the new rhodium(I) complexes of the types Rh(η⁵-cp)(CO)(PTA)] (1), Rh(η⁵-cp)(CO)(P(CH₂CH₂CN)₃)] (2), Rh(η⁵-ind)(CO)(PTA)] (3) and Rh(η⁵-ind)(CO)(P(CH₂CH₂CN)₃)] (4) in isolated yields of 52-75%. All these compounds have been fully characterized by IR, ¹H, ³¹P{¹H} and ¹³C{¹H} NMR, FAB-MS spectroscopies and elemental analyses. Reactivity for the substitution of phosphine is greater for (η⁵-ind)Rh(CO)(L)] comparing to (η⁵-cp)Rh(CO)(L)] because of a flexibility of the indenyl ligand to undergo facile η⁵-η³ coordinative isomerizations. The obtained complexes are active catalyst precursors for the dehydrogenation of propan-2-ol, octane and cyclooctane under photoassisted conditions without any organic hydrogen transfer acceptors, giving TOFs of 26-56 using 3 as precatalyst.