Two Rhodium(III) Ions Confined in a [18]Porphyrin Frame: 5,10,15,20‐Tetraaryl‐21,23‐dirhodaporphyrin

Abstract

Invited for the cover of this issue is the group of Ewa Pacholska‐Dudziak at the University of Wroclaw. The image depicts two rhodium atoms being fixed into the skeleton of 21,23‐dirhodaporphyrin in place of two core nitrogen donors. Read the full text of the article at 10.1002/chem.202201513.

Organometallic Chemistry within the Structured Environment Provided by the Macrocyclic Cores of Carbaporphyrins and Related Systems

“…When treated with sodium dithionite, 550 afforded the corresponding metallachlorin 551 , but this could be oxidized back to 549 with DDQ. Reaction of 547 with [Rh(CO) 2 Cl] 2 in refluxing toluene gave rhodatelluraporphyrin 552 and dirhodaporphyrin 553 [ 346 ]. The dirhodaporphyrin macrocycle was relatively planar and the rhodium atoms were linked via two chloride bridges.…”

Heterobimetallic 21,23-dimetallaporphyrin: activation of metal–metal interactions within the porphyrinoid macrocycle

“…The synthesis of organometallic aromatic 21,23-dirhodaporphyrin 1 containing two rhodium( iii ) ions has been reported. 15 The two metal atoms were incorporated into the porphyrin skeleton in place of two NH groups. The bridged Rh 2 Cl 2 unit situated approximately within the macrocyclic plane contains two 18-electron rhodium( iii ) centres surrounded by octahedral environments.…”

“…The synthesis avoided unlikely four-fold activation of C–H bonds of the formal ligand, 2 , and followed the tellurium-to-metal substitution protocol, employed in our former studies. 15,20–22 The synthetic path, starting with tetrakis(4-methoxyphenyl)-21,23-ditelluraporphyrin 3 , 16 takes advantage of a significant difference in the reactivity of a tellurophene unit towards platinum( ii ) and rhodium( i ) salts, which determines the order of steps. Thus, a single tellurium-to-metal replacement proceeded with platinum( ii ), yielding the known 21-platina-23-telluraporphyrin 4 , 21 which served as a starting material for the second substitution with the more reactive rhodium( i ), as shown in Scheme 1.…”

“…23,24 Generally, it can be considered as a rule, that the tellurium-to-metal substitution in metallaporphyrin synthesis is preceded by the formation of a side-on coordination compound. 15,20–22 The heterobimetallic 5 , reacts with chlorine through an oxidative addition at the platinum( ii ) centre yielding quantitatively the platinum( iv ) analogue, 5-Cl 2 . The reaction can be readily reversed with zinc amalgam.…”

“…Such a macrocyclic in-plane deformation has been previously observed for 21-metalla-23-telluraporphyrins 20,21 and for the 21,23-dirhodaporphyrin 1 . 15 Significantly, the metal atoms in 21-platina-23-rhodaporphyrins are accommodated practically within the macrocyclic plane. The deformation of the skeletons of 5 and 5-Cl 2 did not significantly disturb the delocalization within the 18 π-electron conjugation path of the porphyrinoid C 20 N 2 skeleton, shown with the bold line in Scheme 1.…”