TY - JOUR
T1 - Pentadienyl-Metal-Phosphine Chemistry. 16.1 Reaction Chemistry of (η3-2,4-Dimethylpentadienyl)Rh(PEt3)2 and (η3-2,4-Dimethylpentadienyl)Rh(PMe3)2
AU - Bleeke, John R.
AU - Donaldson, Andrew J.
PY - 1988/7
Y1 - 1988/7
N2 - The reactions of (η3-2,4-dimethylpentadienyl)Rh(PEt3)2 (1) and (η3-2,4-dimethylpentadienyl)Rh(PMe3)2 (2) with CH3+O3SCF3- produce (η5-2,4-dimethylpentadienyl)Rh(PEt3)2(Me)+O3SCF3- (3) and (η6-2,4-dimethylpentadienyl)Rh(PMe3)2(Me)+O3SCF3- (4), respectively. The solid-state structure of 3 has been determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 11.310 (2) Å, b = 13.507 (7) Å, c = 18.226 (3) Å, β = 95.97 (2)°, V = 2769 (3) Å3, and Z = 4. The coordination geometry of 3 is pseudooctahedral, with C(1) C(3), and C(5) of the 2,4-dimethylpentadienyl ligand and P(1), P(2), and C(8) (methyl carbon) occupying the six coordination sites. One of the phosphine ligands resides under the open “mouth” of the 2,4-dimethylpentadienyl ligand, while the other phosphine and the methyl group occupy the coordination sites under the “edges” of the 2,4-dimethylpentadienyl ligand. Upon heating in solution, the 2,4-dimethylpentadienyl ligand in 3 rotates with respect to the RhP2(Me) framework, exchanging the two phosphines, as well as the two ends of the 2,4-dimethylpentadienyl ligand. The energy of activation (ΔG*) for this dynamic process, derived from variable-temperature NMR studies, is 17.0 ± 0.7 kcal/mol. Treatment of 3 and 4 with (Ph3P)2N+Cl- produces (η3-2,4-dimethylpentadienyl)Rh(PEt3)2(Me)(Cl) (5) and (η3-2,4-dimethylpentadienyl)Rh(PMe3)2(Me)(Cl) (6), respectively. Compound 5 crystallizes in the monoclinic space group P21/c with a = 12.962 (3) Å, b = 8.236 (2) Å, c = 22.758 (6) Å, = 94.19 (2)°, V = 2423 (2) Å3, and Z = 4. The coordination geometry of 5 is pseudooctahedral with C(1), C(3) (2,4-dimethylpentadienyl group), P(1), P(2), C(8) (methyl carbon), and Cl occupying the six coordination sites. The phosphines are trans to the 2,4-dimethylpentadienyl group, while the methyl and chloro ligands reside trans to one another. The η3-2,4-dimethylpentadienyl ligand has a syn geometry and is sickle-shaped. In solution, 5 undergoes a dynamic process involving isomerization of the 2,4-dimethylpentadienyl ligand from η3 to η1 coordination (ΔG* = 13.0 ± 0.5 kcal/mol). Treatment of 5 with 2 equiv of PMe3 produces 6 quantitatively. Treatment of 1 with HBF4•OEt2 yields (η4-2,4-dimethylpentadiene)Rh(PEt3)2+BF4- (7), which reacts in situ with benzene and durene to release 2,4-dimethylpentadiene and produce (η6-benzene)Rh(PEt3)2+BF4- (8) and (η6-durene)Rh(PEt3)2+BF4- (9), respectively. Compound 9 crystallizes in the monoclinic space group P21/n with a = 8.349 (2) Å, b = 10.843 (8) Å, c = 29.535 (9) Å, β = 91.96 (2)°, V = 2672 (3) Å3, and Z = 4. In the solid state, the durene ring of 9 is nonplanar: the two unsubstituted durene ring carbon atoms are displaced out of the plane of the four methyl-substituted ring carbon atoms toward the rhodium center. Treatment of 2 with HBF4•OEt2 yields an equilibrium mixture of (η5-2,4-dimethylpentadienyl)Rh(PMe3)2(H)+BF4- (10) and (η4-2,4-dimethyipentadiene)Rh(PMe3)2+BF4- (11). This mixture reacts with benzene and durene to produce (η6-benzene)Rh(PMe3)2+BF4- (12) and (η6-durene)Rh(PMe3)2+BF4- (13), respectively.
AB - The reactions of (η3-2,4-dimethylpentadienyl)Rh(PEt3)2 (1) and (η3-2,4-dimethylpentadienyl)Rh(PMe3)2 (2) with CH3+O3SCF3- produce (η5-2,4-dimethylpentadienyl)Rh(PEt3)2(Me)+O3SCF3- (3) and (η6-2,4-dimethylpentadienyl)Rh(PMe3)2(Me)+O3SCF3- (4), respectively. The solid-state structure of 3 has been determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 11.310 (2) Å, b = 13.507 (7) Å, c = 18.226 (3) Å, β = 95.97 (2)°, V = 2769 (3) Å3, and Z = 4. The coordination geometry of 3 is pseudooctahedral, with C(1) C(3), and C(5) of the 2,4-dimethylpentadienyl ligand and P(1), P(2), and C(8) (methyl carbon) occupying the six coordination sites. One of the phosphine ligands resides under the open “mouth” of the 2,4-dimethylpentadienyl ligand, while the other phosphine and the methyl group occupy the coordination sites under the “edges” of the 2,4-dimethylpentadienyl ligand. Upon heating in solution, the 2,4-dimethylpentadienyl ligand in 3 rotates with respect to the RhP2(Me) framework, exchanging the two phosphines, as well as the two ends of the 2,4-dimethylpentadienyl ligand. The energy of activation (ΔG*) for this dynamic process, derived from variable-temperature NMR studies, is 17.0 ± 0.7 kcal/mol. Treatment of 3 and 4 with (Ph3P)2N+Cl- produces (η3-2,4-dimethylpentadienyl)Rh(PEt3)2(Me)(Cl) (5) and (η3-2,4-dimethylpentadienyl)Rh(PMe3)2(Me)(Cl) (6), respectively. Compound 5 crystallizes in the monoclinic space group P21/c with a = 12.962 (3) Å, b = 8.236 (2) Å, c = 22.758 (6) Å, = 94.19 (2)°, V = 2423 (2) Å3, and Z = 4. The coordination geometry of 5 is pseudooctahedral with C(1), C(3) (2,4-dimethylpentadienyl group), P(1), P(2), C(8) (methyl carbon), and Cl occupying the six coordination sites. The phosphines are trans to the 2,4-dimethylpentadienyl group, while the methyl and chloro ligands reside trans to one another. The η3-2,4-dimethylpentadienyl ligand has a syn geometry and is sickle-shaped. In solution, 5 undergoes a dynamic process involving isomerization of the 2,4-dimethylpentadienyl ligand from η3 to η1 coordination (ΔG* = 13.0 ± 0.5 kcal/mol). Treatment of 5 with 2 equiv of PMe3 produces 6 quantitatively. Treatment of 1 with HBF4•OEt2 yields (η4-2,4-dimethylpentadiene)Rh(PEt3)2+BF4- (7), which reacts in situ with benzene and durene to release 2,4-dimethylpentadiene and produce (η6-benzene)Rh(PEt3)2+BF4- (8) and (η6-durene)Rh(PEt3)2+BF4- (9), respectively. Compound 9 crystallizes in the monoclinic space group P21/n with a = 8.349 (2) Å, b = 10.843 (8) Å, c = 29.535 (9) Å, β = 91.96 (2)°, V = 2672 (3) Å3, and Z = 4. In the solid state, the durene ring of 9 is nonplanar: the two unsubstituted durene ring carbon atoms are displaced out of the plane of the four methyl-substituted ring carbon atoms toward the rhodium center. Treatment of 2 with HBF4•OEt2 yields an equilibrium mixture of (η5-2,4-dimethylpentadienyl)Rh(PMe3)2(H)+BF4- (10) and (η4-2,4-dimethyipentadiene)Rh(PMe3)2+BF4- (11). This mixture reacts with benzene and durene to produce (η6-benzene)Rh(PMe3)2+BF4- (12) and (η6-durene)Rh(PMe3)2+BF4- (13), respectively.
UR - http://www.scopus.com/inward/record.url?scp=0000208841&partnerID=8YFLogxK
U2 - 10.1021/om00097a023
DO - 10.1021/om00097a023
M3 - Article
AN - SCOPUS:0000208841
SN - 0276-7333
VL - 7
SP - 1588
EP - 1596
JO - Organometallics
JF - Organometallics
IS - 7
ER -