Synthesis of catalytically active diene and cyclopentadienyl rhodium halide complexes

Synthesis of Overloaded Cyclopentadienyl Rhodium(III) Complexes via Cyclotetramerization of tert-Butylacetylene

“…Half-sandwich rhodium complexes with cyclopentadienyl ligands such as [(C 5 R 5 )­RhCl 2 ] 2 are widely used as catalysts for various organic transformations: most notably, for the activation and functionalization of C–H bonds of aromatic compounds with coordinating “directing” groups. , While the commercially available catalyst [(C 5 Me 5 )­RhCl 2 ] 2 is the most popular, similar complexes with specifically designed cyclopentadienyl ligands have attracted a great deal of attention because they allow carrying out catalytic reactions with high chemo-, regio-, and enantioselectivity. − The rhodium complexes of this type are usually obtained by the reaction of RhCl 3 with the corresponding cyclopentadienes C 5 R 5 H. − However, there is another, unusual pathway: namely, synthesis by the oligomerization of alkynes (Scheme ). The advantage of this approach (apart from pure academic interest) is the construction of polysubstituted cyclopentadienyl ligands in just two steps from commercially available reagents.…”

Oxidation-promoted synthesis of ferrocenyl planar chiral rhodium(iii) complexes for C–H functionalization catalysis

“…21 This may indicate the formation of the expected compounds, with the bipy and one chloride occupying the three acetonitrile positions, as a mixture of diastereomers (4b+4b'). The 31 P NMR spectrum of 3c + bipy shows a more complex behavior: three doublets, of varying intensity according to the reaction batch, are observed in the same region on the 31 Selected bonds (Å) and angles (°) : Rh(1)-P(1) = 2.3711(3), Rh(1)-C(1) = 1.9912 (12), Rh(1)-C(11) = 2.0330 (12), Rh(1)-N(3) = 2.0808 (10), Rh(1)-N(4) = 2.1291 (10), Rh(1)-F(1) = 2.3500 (7), B(1)-F(1) = 1.4512 (17); P(1)-Rh(1)-C(1) = 90.06 (3), P(1)-Rh(1)-C(11) = 85.92 (3), C(1)-Rh(1)-C(11) = 91.62 (5), P(1)-Rh(1)-N(3) = 174.70 (3), C(1)-Rh(1)-N(3) = 84.73 (4), C(11)-Rh(1)-N(3) = 93.26 (4), P(1)-Rh(1)-N(4) = 102.67 (3), C(1)-Rh(1)-N(4) = 88.90 (4), C(11)-Rh(1)-N(4) = 171.40 (4), N(3)-Rh(1)-N(4) = 78.23 (4), P(1)-Rh(1)-F(1) = 98.50 (2), C(1)-Rh(1)-F(1) = 165.42 (4), C(11)-Rh(1)-F(1) = 100.71 (4), N(3)-Rh(1)-F(1) = 86.80 (3), N(4)-Rh(1)-F(1) = 77.75 (3).…”

Cyclobutadiene Rhodium Complexes as Catalysts for the Synthesis of Amides from Electron‐rich Arenes, Tosyl Azide and CO

“…The reaction of [(C 4 Et 4 )RhI] 2 (Rh3) with CO at room temperature in the absence of other organic reagents produced an interesting product Rh7 instead of the expected 18-electron complex (C 4 Et 4 )Rh(CO) 2 I (Scheme 3). The NMR spectra of Rh7 revealed ambiguous picture with only one type of the cyclobutadiene ligand present in the 13 C NMR spectrum but presumably two sets of cyclobutadiene signals in 1 H NMR spectrum. The IR spectrum of Rh7 contained a single vibration band of CO ligand at 1855 cm À 1 indicating its bridging coordination mode.…”

“…Diene rhodium complexes are readily available [1] from RhCl 3 and are widely used as catalysts for various organic transformations. [2][3][4] However, in most cases the labile diene ligands are replaced at the first step of the catalytic cycle to give some other active species.…”