Photo-aquation of cis-[RuCl2(mPTA)4](CF3SO3)4 in water (mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane)

Abstract

On irradiating the complex cis-[RuCl₂(mPTA)₄](CF₃SO₃)₄ (2) with near UV light at room temperature, (OC-6-13)-[RuCl₂(mPTA)₃(H₂O)](CF₃SO₃)₃ (3) was obtained. Complex 3 is the product of the substitution in 2 of one mPTA by a H₂O molecule and the rearrangement from cis to trans of the two chlorides. The selective photo-reaction of 2 is produced with radiation of 300 < λ < 400 nm or with λ = 367 nm in 50 min (Φ_367 nm (D₂O) = 0.18 ± 0.01). The reaction is not reversible with visible light. The transformation of 2 into 3 is not dependent on the pH but only on the radiation used. Reaction of 3 with NaCl leads to (OC-6-21)-[RuCl₃(mPTA)₃](CF₃SO₃)₂ (4) which could be directly obtained by irradiation of 2 with λ = 367 nm in water and 5 eq. of NaCl (Φ_367 nm (D₂O) = 0.17 ± 0.01). Complex 4 turns slowly to 2 in water with 1 eq. of mPTA under light of λ > 416 nm. Complete conversion of 4 into 2 was achieved after more than one day. All complexes were characterized by elemental analysis, IR and NMR spectroscopy, and 2, 3 and 4 by single crystal X-ray determination. An easy synthesis for the ligand mPTA(CF₃SO₃) is also reported.