Remarkable reactivity of a rhodium(i) boryl complex towards CO₂and CS₂: isolation of a carbido complex

Abstract

The activation of CO2, CS2 as well as of PhNCO at [Rh(Bpin)(PEt3)3] led to C=X bond cleavage and the formation of {RhXBpin} species (X = O, S, N). Treatment of the boryl complex [Rh(Bpin)(PEt3)3] with 0.5 equivalents of CS2 resulted in the fragmentation of CS2 and the formation of the remarkable μ-carbido complex trans-[Rh2(μ-C)(SBpin)2(PEt3)4].

Activation of CS2 and COS at a Rhodium(I) Germyl Complex: Generation of CS and Carbido Complexes

“…[1c], The IR spectrum of complex 2 shows the stretching band of the C≡S ligand at ν̃ = 1278 cm –1 (for 2′ : ν̃ = 1225 cm –1 ), which is in accordance with those of rhodium(I) thiocarbonyl complexes (Figure ). [5b], The structurally related rhodium complex trans ‐[Rh(SBpin)(CS)(PEt 3 ) 2 ] exhibits comparable values [ 12 CS: ν̃ = 1280 cm –1 ; 13 CS: ν̃ = 1227 cm –1 ] . A strong absorption band in the IR spectrum of 3 at ν̃ = 1943 cm –1 can be assigned to the CO stretching vibration and confirms the identity of the carbonyl complex.…”

“…The Rh–P bond lengths [2.3410(5) and 2.3426(5) Å] are in good accordance to the data for known rhodium complexes bearing PEt 3 ligands. [1k], The deviation from ideal square‐planar coordination geometry is very small, as revealed by the P1–Rh1–P2 [172.937(18)°] and S1–Rh1–C1 angles [176.93(6)°]. The S2–C1–Rh1 angle of 177.73(12)° shows that the thiocarbonyl ligand is nearly linear.…”

“…Mechanistically, the generation of 2 and 3 may occur by insertion of CS 2 or COS into the Rh–Ge bond in 4 and 5 yielding complex A (Scheme ), which exhibits a {RhC(X)SGePh 3 } linkage (X = O, S). Comparable intermediates were discussed in reactions of the boryl complex [Rh(Bpin)(PEt 3 ) 3 ] ( 7 ) with CS 2 , CO 2 , or PhNCO . An SGePh 3 migration step to the rhodium center would then give complex 2 or 3 .…”

“…[1k] Recently, we also reported on a reaction of 2 equiv. of the highly reactive rhodium boryl complex [Rh(Bpin)(PEt 3 ) 3 ] ( 7 ) with CS 2 leading to the formation of a dinuclear rhodium µ‐carbido complex trans , trans ‐[Rh 2 (µ‐C)(SBpin) 2 (PEt 3 ) 4 ] ( 10 ) . Comparable fragmentation reactions breaking both C–S bonds in CS 2 are scarce .…”

C=O‐Bindungsspaltung in Kohlendioxid durch einen Eisen(0)‐Phosphininkomplex

“…Die sehr große C=O-Bindungsstärke (die Bindungsenthalpie beträgt 532 kJ mol À1 )stellt jedoch eine große Herausforderung dar. [3] Nichtsdestotrotz haben sich hierfürh ochreduzierte,n ieder-valente,f r ühe 3d-Übergangsmetalle, [4] Edelmetalle [5] und Metalle des f-Blocks [6] bewährt. Im Vergleich ist der Einsatz von gut verfügbaren, in der Erdkruste reichlich vorhandenen, späten 3d-Übergangsmetallen wenig erforscht, obwohl solche Elemente in der Natur eine entscheidende Rolle spielen, so z.…”