In addition to the typical solvents, rhodium(III) m-benziporphyrin reacts with
aldehydes, such as butanal, giving the alkanoyl five-coordinated complex 5-Rh
(RCO) (Scheme 43). The exposure of the solution to UV radiation (λ ¼ 365 nm) in
the presence of dioxygen leads to the regioselective activation of the Rh–C(22) bond
and, consequently, to the incorporation of an oxygen atom. As a result, σ-alkanoyl
rhodium(III) 22-hydroxy-m-benziporphyrin 53-Rh(RCO) was obtained (Scheme
43) [105].
Fig. 4 DFT-optimized molecular models of (a) 5-Rh(Ph) and (b) 5-Rh(Bz) (side view with aryl
groups omitted for clarity). Adapted from Ref. [105]
N
N
N
Ph
Ph
Tol
Tol
Rh
CO
Cl
N
N
N
Ph
Ph
Tol
Tol
Rh
O
butanal, 0,5 h
N
N
N
Ph
Ph
Tol
Tol
Rh
O
O
365 nm
5-Rh(CO)
5-Rh(RCO)
53-Rh(RCO)
Scheme 43 Alkanolyation of rhodium(III) m-benziporphyrin
212
K. Hurej and L. Latos-Grażyński