Macrocyclic Rhodium(III) Hydrides and a Monomeric Rhodium(II) Complex

Several mononuclear N4-macrocyclic
Rh(III) hydrides were prepared and characterized in the solid
state and in
solution. 1H NMR, IR, and UV data are reported.
The complex
{trans-(Cl)([14]aneN4)RhH}2(ZnCl4)·dmso
(1·
dmso) crystallizes in the triclinic system, space group
P1̄, in a unit cell of dimensions a =
10.680(3) Å, b =
13.460(3) Å, c = 14.277(4) Å, α =
86.49(2)°, β = 83.18(2)°, γ = 66.64(2)°.
The data refined to a final value
of R = 0.070 and Rw, = 0.13 based
on 2687 observed reflections. UV photolysis of chloride-free
(H2O)L1RhH2+
results in homolytic Rh−H bond cleavage. The rhodium(II)
product, L1Rh(H2O)2+,
was characterized by ESR
and UV spectroscopies. This species survives in acidic aqueous
solution for over half an hour at room temperature.
The photolysis of
(H2O)L1RhH2+ in the presence
of O2 produces the superoxorhodium(III) ion,
trans-L1RhOO2+.