Merging of inner and outer ruthenium organometallic coordination motifs within an azuliporphyrin framework

Abstract

The insertion of ruthenium(II) into an azuliporphyrin (TPAP) has yielded carbonyl ruthenium(II) azuliporphyrin [Ru(TPAP)(CO)] featuring an equatorial CNNN set of donors. Its azulene moiety serves as the π-coordination platform to accommodate the Ru4(CO)9 cluster. This chemistry proved to be general giving rise to a series of bimetallic complexes [M(TPAP){Ru4(CO)9}] (M = Ru(CO), Ni, Pd, Pt).

C−H and C−M Activation, Aromaticity Tuning, and Co⋅⋅⋅Ru Interactions Confined in the Azuliporphyrin Framework

“…Similar coordination shifts were previously detected for a Ru 4 (CO) 9 cluster π‐bound to azuliporphyrin σ‐complexes and azuliporphyrinogens . Coupling constants for azulene protons of 1‐Co(CO) also decreased from about 10 Hz, typical for azulene derivatives, to 7–9 Hz, as expected for π‐coordinated azulene.…”

“…The previously reported bimetallic complexes [M( 1 )(Ru 4 (CO) 9 )] (M=Ru(CO), Ni, Pd, Pt) stabilized a very close contact between metal centers in the cavity and from π‐coordinated ruthenium clusters, with the M II ⋅⋅⋅Ru 0 distances far below the sum of the van der Waals radii …”

“…Actually, the change in the azuliporphyrin coordination mode determined for 1‐Co(CO) can be readily appreciated by analysis of the upfield coordination shifts of azulene. Here, they are defined as 13 C chemical shift differences between 1‐Co(CO) and regular, neutral ruthenium(II) azuliporphyrin . These values are: 13 C NMR δ =27.5 (C2 1 ,3 1 ), 44.2 (C2 2 ,3 2 ), 60.3 (C2 3 ) ppm, which clearly point toward the seven‐membered ring of the azulene moiety acting as a η 3 ‐allyl coordinating unit of 1‐Co(CO)‐η 3 (Scheme ) .…”

“…The specific features of paramagnetic cobalt(II) azuliporphyrin, including oxygenation to form cobalt(II) 21‐oxyazyliporphyrin, offered considerable promise for further exploration. The azulene moiety of 1‐Co was expected to serve as a π‐coordination platform suitable to accommodate a Ru 4 (CO) 9 cluster following the chemistry that gave rise to a series of bimetallic diamagnetic complexes metal(II) azuliporphyrin [M( 1 )(Ru 4 (CO) 9 )] [M=Ru(CO), Ni II , Pd II , Pt II ] . The docking of the ruthenium clusters to azuliporphyrinogens with unoccupied cavities is documented as well …”

Late transition metal complexes of oxypyriporphyrin and the platinum(II) complex of oxybenziporphyrin

“…Azuliporphyrins (e.g. 3) are dianionic ligands forming nickel(II) [16,17], palladium(II) [16][17][18][19], platinum(II) [17], ruthenium(II) [20], rhodium(III) [21] and iridium(III) [22] complexes. Oxybenziporphyrins can act as trianionic or dianionic ligands, readily affording silver(III) [10,23] and palladium(II) [24] complexes 5 and 6, respectively (Scheme 1).…”