Reaction of Dinuclear Rhodium 4,5-Diazafluorenyl-9-Carboxylate Complexes with H₂ and CO₂

Abstract

The reactivity of the dinuclear Rh(I) 4,5diazafluorenyl-9-carboxylate complex 4 with H 2 was explored in an attempt to reduce the trapped CO 2 -derived moiety. After overnight reaction with H 2 the only observed species at room temperature by NMR spectroscopy was the decarboxylated 4,5-diazafluorenyl (L − ) Rh(III) complex 1. A series of stepwise stoichiometric reactions with H 2 , NMR experiments at low temperatures, trapping experiments with added PPh 3 or CO 2 , and 13 C-labeling experiments were conducted in an attempt to identify the fates of the CO 2 -derived portion of 4 and the second Rh center.

A Phosphine Functionalized β‐Diketimine Ligand for the Synthesis of Manifold Metal Complexes

“…[87,88] Additionally,i nt he 1 HNMR spectrum ar esonance in the upfield region at d = À13.92 ppm (dt, 1 J H,Rh = 21.4 Hz, 2 J H,P = 18.1 Hz) is seen, which can be attributed to the Rh hydride species( see Figure S44). [84,86,88] Further,t he IR spectrum of compound 10 exhibits absorption bands in the region of ṽ = 2040-2080 cm À1 which are characteristic for aR h-H vibration and in-line with literature data. [85,89,90]…”

“…In 10,t he respective metal phosphorous and metal nitrogen bonds are nearly identicala nd within the range of the previously discussed compounds.T hey also match with literature values of comparable Rh III hydride complexes. [83][84][85][86] The bond angles P1-Rh-P2 104.74(3)8 and N1-Rh-N2 91.06(10)8 as well as Cl1-Rh-H1 73(2)8 indicate ar elativelys ymmetric octahedral coordination sphereo ft he Rh III center.…”

Improved Conditions for the Visible-Light Driven Hydrocarboxylation by Rh(I) and Photoredox Dual Catalysts Based on the Mechanistic Analyses

“…CO 2 and H 2 gases were purchased from Taiyo Nippon Sanso Corporation. [Rh(coe) 2 Cl] 2 (Van der Ent et al, 1990), P(4-CF 3 C 6 H 4 ) 3 (Suomalainen et al, 2001), Rh(PPh 3 ) 2 (OAc) ( 5 ) (Grushin et al, 1995), [Rh(cod)(OAc)] 2 (Chatt and Venanzi, 1957), Rh(PPh 3 ) 3 H ( 6 ) (Annibale and Song, 2014), [Ru(bpy) 3 ](PF 6 ) 2 (Damrauer et al, 1997), [Ru(dmbpy) 3 ](PF 6 ) 2 (Damrauer et al, 1997), [Ru(bpz) 3 ](PF 6 ) 2 (Schultz et al, 2015), Ir(ppy) 2 (dtbbpy)(PF 6 ) (Tellis et al, 2014), [Ir(dF(CF 3 )ppy) 2 (dtbbpy)](PF 6 ) (Slinker et al, 2004), fac -Ir(ppy) 3 (Tamayo et al, 2003), and diisopropylethylammonium acetate (Anouti et al, 2008) were prepared according to the published methods. 4-Cyanostyrene ( 1a ) was prepared by Wittig reaction of 4-cyanobenzaldehyde (Falk et al, 2013).…”

Coordination chemistry and applications of versatile 4,5-diazafluorene derivatives

“…116 A series of stepwise stoichiometric reactions with H 2 , NMR experiments at low temperatures with added PPh 3 or CO 2 , along with 13 C-labelling experiments were conducted in an attempt to gain some mechanistic insight. 116 116 It is worth noting that the carboxylic acid intermediate in the reaction between [Rh(daf )(PPh 3 ) 2 ] and CO 2 could not be isolated or even observed in NMR experiments, presumably because the highly basic carbanion in [Rh(daf )(PPh 3 ) 2 ] effected by the electron rich Rh(I) centre deprotonates the carboxylic acid to trigger the formation of the final product too quickly before the concentration of the carboxylic acid intermediate could build up. In order to observe and isolate both the kinetic and thermodynamic products of CO 2 reaction, the slightly less electron donating Cu(I) was used as the spectator metal centre.…”