Synthesis, spectroscopic properties and electrochemistry of Rh2(ap)4(R) where R=CH3 or C6H5 and ap=2-anilinopyridinate anion

Bisaryl Diruthenium(III) Paddlewheel Complexes: Synthesis and Characterization

“…The Ru–C­(sp 2 ) bond lengths here are slightly longer than the corresponding Ru–C­(sp) bond lengths in Ru 2 (DMBA) 4 (CCR) 2 compounds (average 1.97 Å). The argument here is the same provided for the pairs of Rh 2 (ap) 4 (CCH) vs Rh 2 (ap) 4 (Ph) and Ru 2 (ap) 4 (CCR) vs Ru 2 (ap) 4 (Ar): (i) an ipso carbon hybridization change from sp to sp 2 accompanied by an expansion of r covalent, ipso ‑C from 69 to 73 pm and (ii) an increase in steric bulk at the axial site. Despite being electronically distinct, the 4- t Bu and 3,5-(OCH 3 ) 2 substituents do not significantly influence either the Ru–Ru or the Ru–C bond lengths because the aryl ligand π orbitals are involved in neither the net single δ bond nor the Ru–C σ bonds.…”

“…Until recently, the only example of an M 2 L 4 (aryl) n compound with an intact M−M bond and unperturbed paddlewheel came from the laboratories of Bear and Kadish (C4). 35 Recently, we reported the first examples of diruthenium paddlewheel aryls prepared via metathesis with aryllithiums (C5). 36 These compounds are remarkably stable under ambient conditions and exhibit rich electrochemical properties by supporting up to four reversible oxidations and one reversible reduction.…”

“…Since then, their group has investigated other bisaryl complexes of the form Rh 2 (L) 4 (aryl) 2 ( C3 ). − Interestingly, in these examples, the Rh–Rh bond is absent as a result of a drastic change in the electronic structure of the Rh 2 core to π 4 δ 2 π* 4 δ* 2 . Until recently, the only example of an M 2 L 4 (aryl) n compound with an intact M–M bond and unperturbed paddlewheel came from the laboratories of Bear and Kadish ( C4 ) …”

Electrosynthesis of Rh2(dpf)4(R) where dpf = N,N′-diphenylformamidinate anion and R = CH3, C2H5, C3H7, C4H9 or C5H11

“…The final spectral product in Fig. 2b has a band at 473 nm and this can be compared to singly reduced Rh 2 (ap) 4 (C 6 H 5 ) 17 which has a single absorption band at 493 nm in the UV-visible spectrum (see Table 1).…”

“…16 Our own laboratory has been interested over the last two decades in the synthesis and electrochemical characterization of dirhodium complexes where the Rh 2 n unit of Rh 2 L 4 varies from n = +3 to n = +6 with one primary emphasis of our studies being to elucidate how changes in the axial and bridging ligands will effect the structural, electrochemical and spectroscopic properties of these compounds. 3,[5][6][7][8] We recently reported the characterization of Rh 2 (ap) 4 (CH 3 ) and Rh 2 (ap) 4 (C 6 H 5 ) which were prepared using standard synthetic methods 17 and have now extended our study to include a series…”