TY - JOUR
T1 - Addition of Small Molecules to (η–C5H5)2Rh2(CO)(CF3C2CF3). 5.1 The Formation of Several Different Bridging Diene and Dienone Ligands by the Co-oligomerization of HC2-t-Bu with the Coordinated CF3C2CF3
AU - Dickson, Ron S.
AU - Fallon, Gary D.
AU - McLure, Felicity I.
AU - Nesbit, Rhonda J.
PY - 1987/2/1
Y1 - 1987/2/1
N2 - Six products are obtained when (η–C5H5)2Rh2(CO)(CF3C2CF3) is treated with tert-butylacetylene at room temperature; another two are formed during workup of the reaction mixture. Two of the products are isomers of the bridging pentadienone complex (η-C5H5)2Rh2{C4(CF3)2H-t-BuCO}. In the major isomer 1 (10% yield), the configuration of the bridging ligand is -C(CF3)═C(CF3)C(O)C(H)═C(t-Bu)-; the reverse arrangement of H and t-Bu is indicated for the minor isomer 2 (5% yield). A metalladiene complex (η-C5H5)2Rh2{C4(CF3)2H-t-Bu} (3) is the major product (29% yield) of the reaction. Only one isomer is obtained, and it has the C(t-Bu) and C(H) carbons a and β, respectively, to the ring metal. This product is isolated only when the product mixture is chromatographed on “nonactivated” supports. With oven-dried supports, 3 is converted to a new complex of formula (η-C5H5)2Rh2{C4(CF3)2H-t-BuO2} (4). The structure of 4 has been determined from X-ray diffraction data; the bridging ligand is an unsaturated keto-ether of the type O═C(t-Bu)C(H)═C(CF3)OC(CF3)- which is attached to the Rh-Rh bond through the ketonic oxygen, the alkene bond, and the terminal (CF3)C: carbon. Another major product is formulated as (n-C5H5)2Rh2(CO){C4(CF3)2H-t-BuCO} (5) (17% yield). This complex contains a terminal carbonyl and a bridging cyclopentadienone ligand. Crystal structure determination establishes that the bridging ligand is bound to one rhodium by a cr-bond from a C(CF3) ring carbon and to the other rhodium by an η3-allyl attachment from C(CF3)═C(H)═C(t-Bu). Decarbonylation of this complex with Me3NO results in opening of the cylopentadienone ring to give complex 1. The final major product (19% yield) is (η-C5H5)2Rh2-(C2H-t-Bu){C4(CF3)2H-t-BuCO} (6). The molecular geometry of 6 has been determined by X-ray analysis. It has two bridging groups. One is a cyclopentadienone ligand which is η2,η2-attached to the Rh-Rh bond; the other is a μ-η2-vinylidene group C=CH-t-Bu. This complex isomerizes during chromatography. The dicarbonyl complex (η-C5H5)2Rh2(CO)2(CF3C2CF3) (12% yield) is also a product of the reaction. Crystal data: complex 4, C20H20F6O2Rh2, triclinic, PĪ, a = 16.455 (8) Å, b = 13.836 (7) Å, c = 10.876 (5) Å, α = 115.09 (10)°, β= 98.64 (10)°, γ = 97.91 (10)°, Z = 4, final R = 0.052, Rw= 0.051 from 6915 observed reflections (12595 measured); complex 5, C22H20F6O2Rh2, monoclinic, P21/n, a = 14.590 (7) Å, b = 16.694 (8) Å, c = 9.407 (5) Å, β= 104.90 (10)°, Z = 4, final R = 0.054, Rw= 0.052 from 3472 reflections (6450 measured); complex 6, C27H30F6ORh2, orthorhombic, P212121, a = 16.283 (8) Å, b = 14.946 (7) Å, c = 10.571 (5) Å, Z = 4, final R = 0.060, Rw= 0.054 from 1739 reflections (4179 measured).
AB - Six products are obtained when (η–C5H5)2Rh2(CO)(CF3C2CF3) is treated with tert-butylacetylene at room temperature; another two are formed during workup of the reaction mixture. Two of the products are isomers of the bridging pentadienone complex (η-C5H5)2Rh2{C4(CF3)2H-t-BuCO}. In the major isomer 1 (10% yield), the configuration of the bridging ligand is -C(CF3)═C(CF3)C(O)C(H)═C(t-Bu)-; the reverse arrangement of H and t-Bu is indicated for the minor isomer 2 (5% yield). A metalladiene complex (η-C5H5)2Rh2{C4(CF3)2H-t-Bu} (3) is the major product (29% yield) of the reaction. Only one isomer is obtained, and it has the C(t-Bu) and C(H) carbons a and β, respectively, to the ring metal. This product is isolated only when the product mixture is chromatographed on “nonactivated” supports. With oven-dried supports, 3 is converted to a new complex of formula (η-C5H5)2Rh2{C4(CF3)2H-t-BuO2} (4). The structure of 4 has been determined from X-ray diffraction data; the bridging ligand is an unsaturated keto-ether of the type O═C(t-Bu)C(H)═C(CF3)OC(CF3)- which is attached to the Rh-Rh bond through the ketonic oxygen, the alkene bond, and the terminal (CF3)C: carbon. Another major product is formulated as (n-C5H5)2Rh2(CO){C4(CF3)2H-t-BuCO} (5) (17% yield). This complex contains a terminal carbonyl and a bridging cyclopentadienone ligand. Crystal structure determination establishes that the bridging ligand is bound to one rhodium by a cr-bond from a C(CF3) ring carbon and to the other rhodium by an η3-allyl attachment from C(CF3)═C(H)═C(t-Bu). Decarbonylation of this complex with Me3NO results in opening of the cylopentadienone ring to give complex 1. The final major product (19% yield) is (η-C5H5)2Rh2-(C2H-t-Bu){C4(CF3)2H-t-BuCO} (6). The molecular geometry of 6 has been determined by X-ray analysis. It has two bridging groups. One is a cyclopentadienone ligand which is η2,η2-attached to the Rh-Rh bond; the other is a μ-η2-vinylidene group C=CH-t-Bu. This complex isomerizes during chromatography. The dicarbonyl complex (η-C5H5)2Rh2(CO)2(CF3C2CF3) (12% yield) is also a product of the reaction. Crystal data: complex 4, C20H20F6O2Rh2, triclinic, PĪ, a = 16.455 (8) Å, b = 13.836 (7) Å, c = 10.876 (5) Å, α = 115.09 (10)°, β= 98.64 (10)°, γ = 97.91 (10)°, Z = 4, final R = 0.052, Rw= 0.051 from 6915 observed reflections (12595 measured); complex 5, C22H20F6O2Rh2, monoclinic, P21/n, a = 14.590 (7) Å, b = 16.694 (8) Å, c = 9.407 (5) Å, β= 104.90 (10)°, Z = 4, final R = 0.054, Rw= 0.052 from 3472 reflections (6450 measured); complex 6, C27H30F6ORh2, orthorhombic, P212121, a = 16.283 (8) Å, b = 14.946 (7) Å, c = 10.571 (5) Å, Z = 4, final R = 0.060, Rw= 0.054 from 1739 reflections (4179 measured).
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U2 - 10.1021/om00145a001
DO - 10.1021/om00145a001
M3 - Article
AN - SCOPUS:4243165450
VL - 6
SP - 215
EP - 223
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 2
ER -