Consecutive C F Bond Activation and C F Bond Formation at Heteroaromatics at Rhodium: The Peculiar Role of FSi(OEt) 3

Transcription

1 Electronic Supplementary Material (ESI) for Chemical Science. This journal is The Royal Society of Chemistry 015 Supplementary Material Consecutive C Bond Activation and C Bond ormation at eteroaromatics at Rhodium: The Peculiar Role of Si(OEt) 3 A. L. Raza a and T. Braun a a umboldt-universität zu Berlin, Department of Chemistry, Brook-Taylor-Straße, D-189 Berlin, Germany. thomas.braun@chemie.hu-berlin.de Experimental section The synthetic work was carried out with a Schlenk line under an atmosphere of argon or in an argonfilled glove-box with oxygen levels below 10 ppm. All solvents were dried and purified by conventional methods and distilled under argon before use. [D 6 ]benzene, [D 8 ]toluene and [D 8 ]T were purified by distillation from Na/K under argon. [Rh{Si(OEt) 3 }( ) 3 ] (1), [Rh()( ) 3 ] (6), [Rh(C 3 )( ) 3 ] (9), SiEt 3 and Si(OEt) 3 were prepared according to the literature. 1 Alternatively, the latter was formed in situ. Compound 1 was freshly prepared before usage. In all experiments with 9 as starting compound, 9 was employed as a solution with a concentration of mmol ml -1.,3,5,6-Tetrafluoropyridine,,3,,6-tetrafluorobenzene,,3,5,6-tetrafluorobenzene,,3,5- trifluoropyridine and,3,6-trifluoropyridine were supplied from ABCR. TAS was obtained from Sigma-Aldrich. The NMR spectra were acquired on a Bruker DPX 300, Bruker Avance 300 or a Bruker AV 00 NMR spectrometer. The 1 chemical shifts were referenced to the residual signal of non-deuterated solvents at δ =.16 ppm for benzene, δ =.08 ppm for toluene and δ = 3.58 ppm for T. 9 Si NMR spectra were referenced to external TMS at δ = 0 ppm. 19 NMR spectra were referenced externally to CCl 3 at δ = 0 ppm and 31 P NMR spectra were referenced externally to 3 PO at δ = 0 ppm. As internal standards, capillaries with C 6 6 /C 6 D 6 or 3 PO /D O were used. Liquid injection field desorption ionization (LIDI) mass spectra were measured at a Micromass Q-TO mass spectrometer equipped with a LIDI 00 (Linden CMS) ion source. 1

2 General procedure for the activation of,3,5,6-tetrafluoropyridine at [Rh{Si(OEt) 3 }( ) 3 ] (1) and the subsequent generation of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () in the presence of triethoxyfluorosilane,3,5,6-tetrafluoropyridine (5.5 µl, 0.05 mmol) was added to a freshly prepared solution of [Rh{Si(OEt) 3 }( ) 3 ] (1) (0.053 mmol) in [D 8 ]-toluene (0. ml) or as an alternative in [D 8 ]-T (0. ml) in a glass NMR tube. The C activation reaction was monitored by 31 P{ 1 } NMR spectroscopy until the silyl complex 1 was quantitatively converted into [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), [Rh(- C 5 N){η -Si(OEt) 3 }( ) ] (3) and [Rh(-C 5 N)( ) 3 ] () (ratios between :1:1 and 80:8:1). Then NaOEt or EtO was added (Table 1). The formation of [Rh(-C 5 N)( ) 3 ] () from [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () and [Rh(-C 5 N){η -Si(OEt) 3 } ) ] (3) was monitored by 31 P{ 1 } and 19 { 1 } NMR spectroscopy. Internal standards revealed a full conversion of (between.5 and 18.5 h). The 1, 9 Si MBC NMR spectrum showed the formation of tetraethoxysilane, which was identified by comparison of its NMR spectroscopic data with the literature. The formation of pyridyl complexes (, 5, ) and of dihydrido silyl complex [Rh() {Si(OEt) 3 }( ) 3 ] (Table 1) was observed in a ratio of 9:6. In subsequent reactions with intermediary the hydrodefluorination product [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () was formed from [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () and the product of the oxidative addition [Rh() (-C 5 N)( ) 3 ] (5) was generated from [Rh(- C 5 N)( ) 3 ] (). Competing reactions are shown in the Scheme below. The stoichiometry of the reactions, the reaction times and product ratios are listed in Table 1. MS (LIDI, [D 8 ]toluene): m/z = 60 [M] + (1), 589 [M] + (), 60 [M] + ().

3 Tabel S1: Additives, reaction times and observed ratios of the rhodium pyridyl complexes [Rh(- C 5 N)( ) 3 ] (), [Rh() (-C 5 N)( ) 3 ] (5) and [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () that were obtained after the conversion of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () was completed. Ratios were determined by integration of 31 P{ 1 } NMR spectra. entry additive mmol time (h) none EtO 0.0 (.5 µl) 6, NaOEt 0.06 ( mg) 9 8 traces 16 NaOEt 0.03 ( mg) NaOEt, [D 8 ]T 0.03 ( mg), [a] Cs 0.01 ( mg) [a] Li 0.06 (1.5 mg) 8 [a,b] SiEt (10 µl) [a] No conversion of [Rh{-(3,5,6-C 5 3N)}() 3] () was observed. [b] SiEt 3 and small amounts of were added after removing Si(OEt) 3 in vacuum and dissolving the residue in [D 8]toluene. 3

4 igure S1: Plot of the ratio of the fluorination products (sum of the integrals of the signals for the complexes 3, and 5) as a function of the reaction time (h). Plots 1-5 correspond to the entries in Table S1. Reaction conditions are listed in Table S1. product formation 100,000 80,000 60,000 0, ,000,000,000 1,000,000 3,000,000 5,000 6,000,000 8,000 9,000 10,000 time (h) Competing reaction routes of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () after treatment with triethoxyfluorosilane to yield by fluorination. The reactions are induced by the intermediate generation of dihydrogen and SiOEt 3 from 3. N Rh N Rh 6 N + - N Rh Si(OEt) 3 N Rh 5 N N Rh Si(OR) 3 Rh Rh Si(OEt) 3 3

5 igure S: Part of the 31 P{ 1 } NMR spectra of the fluorination of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () in presence of Si(OEt) 3 and NaOEt (entry 3, Table S1; recorded on a Bruker Avance 300 spectrometer at 8. Mz in [D 8 ]toluene) h h 5 h 3 h h h N Si(OEt) 3 N Rh Rh Rh Si(OEt) N N N Rh Rh Rh Si(OR) 3 Rh 5 + 5

6 igure S3: Part of the 19 { 1 } NMR spectra of the fluorination of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () in presence of Si(OEt) 3 and NaOEt (entry 3, Table S1; recorded on a Bruker Avance 300 spectrometer at 8. Mz in [D 8 ]toluene). 10 h 5 5 h 5 h 3 h h 1 h * N N Rh Rh Si(OEt) 3 N Si(OEt) N N N Rh Rh Rh N 5 6

7 igure S: Part of the 1, 9 Si MBC NMR spectrum of the formation of [Rh{-(3,5,6- C 5 3 N)}( ) 3 ] () and subsequent fluorination in presence of Si(OEt) 3 and NaOEt (entry 3, Table S1; recorded on a Bruker Avance 300 spectrometer at 59.6 Mz in [D 8 ]toluene); a) during C- activation phase; b) after fluorination. a) [Rh(-C 5 N){η -Si(OEt) 3 ( ) 3 ] (3) (above: correlation to C hydrogens of the Si bound Et groups; below: cross peak to the hydrogen atom of the silane ligand) * fluorotriethoxysilane * 3 3

8 b) + tetraethoxysilane + 8

9 luorination of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () by reaction of with TAS,3,5,6-Tetrafluoropyridine (5.3 µl, mmol) was added to a solution of [Rh{Si(OEt) 3 }( ) 3 ] (1) (33 mg, mmol) in [D 8 ]-toluene (0.3 ml). The reaction progress was monitored by NMR spectroscopy until the silyl complex 1 was fully consumed to give [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), [Rh(-C 5 N){η -Si(OEt) 3 }( ) ] (3) and [Rh(-C 5 N)( ) 3 ] () (ratio: 68:1:15 after 1.5 h). All volatile compounds were removed in vacuum and the residue was dissolved in [D 8 ]-T (0.35 ml) and triethyphoshine (1 µl, 0,00 mmol) was added. The solution was added to TAS (15 mg, 0.05 mmol) in an NMR tube. The formation of [Rh(-C 5 N)( ) 3 ] () was monitored by 31 P{ 1 } and 19 { 1 } NMR spectroscopy. After 0. h the 31 P{ 1 } NMR spectrum reveals the presence of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), [Rh(-C 5 N)( ) 3 ] (), [Rh{-(,3,5-C 5 3 N)}( ) 3 ] (), [Rh( ) 3 ] (8) and additional rhodium complexes, that could not be characterized further, in a ratio of 3:35:13:10:39. 3 Synthesis of [Rh(-C 5 N){η -Si(OEt) 3 }( ) ] (3) To a solution of Rh(-C 5 N)( ) 3 ] () (3 mg, mmol) triethoxysilane was added (10 µl, 0.05 mmol). After 0 min the formation of [Rh(-C 5 N){η -Si(OEt) 3 }( ) ] (3) and triethylphosphine was observed. Compounds 3 and are present in a 1:3 ratio according the 31 P{ 1 } NMR spectra. NMR data of 3: 1 NMR (300.1 Mz, [D 8 ]toluene, 300 K): δ = 3.9 (q, 3 J(,) = 6.8 z, 6, SiOC C 3 ), 1.9 ppm (m, dt in the 1 { 19 } NMR spectrum, 1 J(,Rh) = 0 z, J(,P) = 1 z, 1, SiOC C 3 ). The resonances for the ethyl groups of the phosphine ligands and the methyl 9

10 group of the ethoxy substituents in 3 are covered by signals of, triethoxysilane and triethylphosphine; 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = 99.8 (m, ), 11.3 (m, 1), 11. ppm (m, 1); 31 P{ 1 } NMR (11.5 Mz, [D 8 ]toluene, 300 K): δ(ppm) =. (d, 1 J(Rh,P) = 11 z); 1, 9 Si MBC NMR (300.1/59.6 Mz, [D 8 ]toluene, 300 K): δ { 1 / 9 Si} = / 39 (SiOC C 3 ), 13/ 39 ppm (SiOC C 3, dd in the 1 domain 1 J(,Si) = 65 z, 1 J(,Rh) = 0 z). ormation of Si(OEt) 3 Pentafluoropyridine (.5 µl, 0.0 mmol) was added to a solution of [Rh{Si(OEt) 3 }( ) 3 ] (1) (0.053 mmol) in [D 8 ]-toluene (0. ml). After 15 min all volatile compounds were removed in vacuum and collected in a cold trap. NMR spectra of the solution show the presence of solely Si(OEt) 3. The latter was used in the reaction with the complexes and 10-1 (see page 15). NMR data of Si(OEt) 3 : 1 NMR (300.1 Mz, [D 8 ]toluene, 300 K): δ = 3.8 (q, 3 J(,) =.0 z, 6, SiOC C 3 ), 1.1 ppm (t, 3 J(,) =.0 z, 9, SiOC C 3 ); 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = 15. ppm (s, 9 Si satellites, J(Si,) = 0 z, 1); 1, 9 Si MBC NMR (300.1/59.6 Mz, [D 8 ]toluene, 300 K): δ { 1 / 9 Si} = / 89 ppm (SiOC C 3 ). ormation of [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () via C- Activation at [Rh( ) 3 ] (6) N Rh 6 + N Rh 10

11 ,3,5-Trifluoropyridine (.8 µl, 0.03 mmol) was added to a solution of [Rh( ) 3 ] (6) (0.03 mmol) in [D 6 ]-benzene (0. ml). After 1 h the 19 { 1 } NMR spectrum reveals the formation of [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () and the presence of residual,3,5-trifluoropyridine in a 1:1 ratio. NMR data for : 1 NMR (300.1 Mz, [D 8 ]toluene, 300 K): δ =.6 (m, 1, C 5 3 N), 1.5 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 6, PC C 3 ), 1. (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 1, PC C 3 ), 1.1 (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 9, PC C 3 ), 1.0 ppm (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 18, PC C 3 ). 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = (m, 1), 10.5 (m, 1), 11.5 ppm (m, 1). 31 P{ 1 } NMR (11.5 Mz, [D 8 ]toluene, 300 K): δ = 1.5 (dtm, 1 J(Rh,P) = 18 z, J(P,P) = 0 z, 1P), 13.3 ppm (dd, 1 J(Rh,P) = 1 z, J(P,P) = 0 z, P). ormation of,3,5-trifluoropyridine from [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () A reaction mixture of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), [Rh(-C 5 N){η -Si(OEt) 3 }( ) ] (3) and [Rh(-C 5 N)( ) 3 ] () (ratio: 81:16:3) was prepared via the described procedure (see page ). All volatile compounds were removed in vacuum and a solution of ( µl, 0.01 mmol) in [D 8 ]toluene (0. ml) was added. ydrogen was bubbled for 0 sec into the solution. After 30 min the 31 P{ 1 } NMR spectrum revealed the formation of [Rh( ) 3 ] (), [Rh() {Si(OEt) 3 }( ) 3 ], [Rh(-C 5 N)( ) 3 ] () and [Rh() (-C 5 N)( ) 3 ] (5) in a ratio of 53:1::10. In the 19 NMR spectrum,3,5-trifluoropyridine and,3,5,6-tetrafluoropyridine were detected additionally. ormation of [Rh( ) 3 ] (8) by reaction of of with water and Si(OEt) 3 A reaction mixture of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), [Rh(-C 5 N){η -Si(OEt) 3 }( ) ] (3), [Rh(-C 5 N)( ) 3 ] (), and Si(OEt) 3 was prepared via the described procedure (6:16:8; see 11

12 page ). Water (0.5 µl, 0.8 mmol) was added. Monitoring the reaction by 31 P{ 1 } NMR spectroscopy revealed after.5 h the formation of [Rh( ) 3 ] (8) from [Rh{-(3,5,6- C 5 3 N)}( ) 3 ] (). Complex 8 was identified by its NMR spectroscopic data. 3 ormation of [Rh( ) 3 ] (8) from [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] () and an source A reaction mixture of [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), [Rh(-C 5 N){η -Si(OEt) 3 }( ) ] (3), [Rh(-C 5 N)( ) 3 ] (), and Si(OEt) 3 was prepared via the described procedure (see page ). All volatile compounds were removed in vacuum and the residue was disolved in [D 8 ]-toluene (0. ml) and triethyphoshine (1 µl, 0.00 mmol). In a PA NMR tube a source was added. This was either 3 NEt 3 ( µl) or a solution in water (.5 µl of a 0 % solution) or ethanol ( µl of a 18 M solution). Monitoring the reaction by 31 P{ 1 } NMR spectroscopy revealed after 1.5 h in each case the formation of [Rh( ) 3 ] (8) from [Rh{-(3,5,6-C 5 3 N)}( ) 3 ] (), whereas 3 and did not react. Complex 8 was identified by its NMR spectroscopic data. 3 ormation of [Rh(,3,,6-C 6 )( ) 3 ] (10),,5,6-Tetrafluorobenzene (10 µl, mmol) was added to a solution of [Rh(C 3 )( ) 3 ] (9) (0.053 mmol) in [D 8 ]-toluene (0.5 ml) and the reaction mixture was stirred for 30 min at 0 C. The 31 P 1 {} spectrum reveals the conversion of the methyl complex 9 into 10 and [Rh(p-tol)( ) 3 ]. [1b] The 1 NMR spectrum reveals a ratio of 10 and [Rh(p-C 6 D CD 3 )( ) 3 ] of 9:3. The formation of the latter results from a C activation reaction of toluene at 9. Evaporation of the solvent and residual,,5,6-tetrafluorobenzene yielded a yellow solid. 1

13 NMR data for 10: 1 NMR (300.1 Mz, [D 8 ]toluene, 300 K): δ = 6. (m, s, br in the 1 { 19 } NMR spectrum, 1, C 6 ), 1. (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 6, PC C 3 ), 1.3 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 1, PC C 3 ), 1.0 (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 9, PC C 3 ), 0.9 ppm (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 18, PC C 3 ). 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = 88.5 (m, 1), 10.6 (m, 1), 19. (m, 1), 1.1 ppm (m, 1). 31 P{ 1 } NMR (11.5 Mz, [D 8 ]toluene, 300 K): δ = 13.9 (dtm, 1 J(Rh,P) = 13 z, J(P,P) = 39 z, 1P), 9.6 ppm (dd, 1 J(Rh,P) = 1 z, J(P,P) = 39 z, P). MS (LIDI, [D 8 ]toluene): m/z = 606 [M] +. ormation of [Rh(,3,5,6-C 6 )( ) 3 ] (11) 1,,,5-Tetrafluorobenzene (10 µl, mmol) was added to a solution of [Rh(C 3 )( ) 3 ] (9) (0.053 mmol) in [D 8 ]-toluene (0.5 ml) and the reaction mixture was stirred for 30 min at 0 C. The 31 P 1 {} spectrum reveals the conversion of the methyl complex 9 into 11. As additional product [Rh(p-C 6 D CD 3 )( ) 3 ], resulting from C activation of toluene with 9, was observed. [1b,] 11 and [Rh(p-C 6 D CD 3 )( ) 3 ] were obtained in a ratio of 98: (determined via integration in the 1 NMR spectrum). Evaporation of the solvent and residual 1,,,5-tetrafluorobenzene yielded a yellow solid. NMR data for 11: 1 NMR (300.1 Mz, [D 8 ]toluene, 300 K): δ = 6.5 (m, s in the 1 { 19 } NMR spectrum, 1, C 6 ), 1. (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 6, PC C 3 ), 1.3 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 1, PC C 3 ), 1.0 (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 9, PC C 3 ), 0.9 ppm (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 18, PC C 3 ). 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = 110. (m, ), 1.3 ppm (m, ). 31 P{ 1 } NMR (11.5 Mz, [D 8 ]toluene, 300 K): δ = 18.5 (dtm, 1 J(Rh,P) = 13 z, J(P,P) = 39 z, 1P),1.3 ppm (dd, 1 J(Rh,P) = 1 z, J(P,P) = 39 z, P). MS (LIDI, [D 8 ]toluene): m/z = 606 [M] +. 13

14 ormation of [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () by C Activation at [Rh(C 3 )( ) 3 ] (9),3,5-Trifluoropyridine (6.9 µl, 0.09 mmol) was added to a solution of [Rh(C 3 )( ) 3 ] (9) (0.09 mmol) in [D 8 ]-toluene (0.8 ml) and the reaction mixture was stirred for 90 min at 0 C. The 31 P 1 {} spectrum reveals the conversion of the methyl complex 9 into [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () and [Rh(p-C 6 D CD 3 )( ) 3 ] (95:5). [1b,] The solution of was in situ used for further reactions because of the low solubility of after evaporation of the solvent. or NMR data of see page 11. ormation of [Rh{-(,3,6-C 5 3 N)}( ) 3 ] (1),3,6-Trifluoropyridine (6.9 µl, 0.09 mmol) was added to a solution of [Rh(C 3 )( ) 3 ] (9) (0.09 mmol) in [D 8 ]-toluene (0.8 ml) and stirred for 90 min at 0 C. The 31 P 1 {} spectrum reveals the conversion of the methyl complex 9 into [Rh{-(,3,6-C 5 3 N)}( ) 3 ] (1). As additional product [Rh(p-C 6 D CD 3 )( ) 3 ] was observed in a ratio of 98:. [1b,] The ratio was determined by integration from the 1 NMR spectrum. The solution of 1 was in situ used for further reactions because of the low solubility of 1 after evaporation of the solvent. NMR data for 1: 1 NMR (300.1 Mz, [D 8 ]toluene, 300 K): δ =. (m, 1, C 5 3 N), 1. (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 6, PC C 3 ), 1.3 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 1, PC C 3 ), 1.0 (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 9, PC C 3 ), 0.9 ppm (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.6 z, 18, PC C 3 ). 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = 89. (m, 1), 10.6 (m, 1), 15.8 ppm (m, 1). 31 P{ 1 } NMR (11.5 Mz, [D 8 ]toluene, 300 K): δ = 18.1 (dtm, 1 J(Rh,P) = 10 z, J(P,P) = 39 z, 1P), 1. ppm (dd, 1 J(Rh,P) = 16 z, J(P,P) = 39 z, P). 1

15 General procedure for the treatment of the complexes, 10-1 with triethoxyfluorosilane A solution of the tetrafluorophenyl complexes 10 or 11 in [D 8 ]-T (0.0 mmol in 0.5 ml) or a solution of the trifluoropyridyl complexes and 1 in [D 8 ]-toluene (0.0 mmol in 0.5 ml) was treated with a solution of Si(OEt) 3 (0.0 mmol) in [D 8 ]-Toluene (0.15 ml, prepared according the procedure which is descripted at page 10). NaOEt ( mg, 0.03 mmol) was added. The reaction mixtures were monitored by NMR spectroscopy. No reaction of the rhodium complexes with Si(OEt) 3 was observed. Syntheses of [Rh{-(3,5-C 5 N)}( ) 3 ] (13) and in situ fluorination with triethoxyfluorosilane as fluoride source to yield [Rh{-(,3,5-C 5 3 N)}( ) 3 ] (),3,5-Trifluoropyridine (. µl, mmol) was added to a solution of [Rh{Si(OEt) 3 }( ) 3 ] (1) (0.053 mmol) in [D 8 ]-toluene (0.3 ml). After 1.5 h the 31 P{ 1 } NMR spectrum shows that 1 was fully consumed to give [Rh(-3,5-C 5 N)( ) 3 ] (13) and triethoxyfluorosilane as well as small amounts of (by fluorination of 13). [Rh(-3,5-C 5 N)( ) 3 ] (13) was characterized in solution by NMR spectroscopy. The formation of [Rh{-(,3,5-C 5 3 N)}( ) 3 ] () from 13 and triethoxyfluorosilane was monitored by 31 P{ 1 } and 19 { 1 } NMR spectroscopy. Complex was generated after 1 hours. Additionally to the generation of and [Rh(-3,5-C 5 N)( ) 3 ] (13), the formation of [Rh( ) 3 ] (6) and other rhodium complexes, which were not identified further, was observed according to the 31 P{ 1 } NMR spectrum (ratio: 58:18:13:11). NMR data for 13: 1 NMR (300.1 Mz, [D 6 ]benzene, 300 K): δ = 8.6 (m, d in the 1 { 19 } NMR spectrum, 3 J(,) =.3 z, 1, C 5 N), 6. (m, ddm in the 1 { 31 P} NMR spectrum, 3 J(,) = 1.1 z, 3 J(,) =.3 z, 1, C 5 N), 1.6 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.5 z, 6, PC C 3 ), 1.5 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =.5 z, 1, PC C 3 ), 1.1 (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.5 z, 9, PC C 3 ), 1.0 ppm (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =.5 z, 18, PC C 3 ); 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = (s, 1), 16.1 ppm (d, 3 J(,) = 1.1 z, s in the 1 { 19 } NMR spectrum, 1); 31 P{ 1 } NMR (

16 Mz, [D 8 ]toluene, 300 K): δ = 0.8 (dtm, 1 J(Rh,P) = 11 z, J(P,P) = 3 z, 1P), 16. ppm (ddm, 1 J(Rh,P) = 155 z, J(P,P) = 3 z, P). or NMR data of see page 11. Syntheses of [Rh{-(5,6-C 5 N)}( ) 3 ] (1) and in situ fluorination with triethoxyfluorosilane as fluoride source to yield [Rh{-(,3,6-C 5 3 N)}( ) 3 ] (1) Si(OEt) 3 Rh N N Rh + Si(OEt) 3 siloxane formation N Rh 1 1 1,3,6-Trifluoropyridine (. µl, mmol) was added to a solution of [Rh{Si(OEt) 3 }( ) 3 ] (1) (0.053 mmol) in [D 8 ]-toluene (0.3 ml). After 1 h the 31 P{ 1 } NMR spectrum shows that 1 was fully consumed to give [Rh{-(5,6-C 5 N)}( ) 3 ] (1) and triethoxyfluorosilane as well as small amounts of 1 (by fluorination of 1). [Rh{-(5,6-C 5 N)}( ) 3 ] (1) was characterized in solution by NMR spectroscopy. The formation of [Rh{-(,3,6-C 5 3 N)}( ) 3 ] (1) from 1 was observed by 31 P{ 1 }, and 19 { 1 } spectroscopy. After 16 h the 31 P{ 1 } NMR spectrum displayed the complexes [Rh{-(5,6-C 5 N)}( ) 3 ] (1), [Rh{-(,3,6-C 5 3 N)}( ) 3 ] (1) and [Rh( ) 3 ] (6) and rhodium compounds which could not be further characterized in a ratio of 3:59:18:1. NMR data for 1: 1 NMR (300.1 Mz, [D 6 ]benzene, 300 K): δ = 6.5 (m, 1, C 5 N), 6.0 (m, 1, C 5 N), 1.6 (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 6, PC C 3 ), 1. (m, q in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 1, PC C 3 ), 1.1 (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 9, PC C 3 ), 1.0 ppm (m, t in the 1 { 31 P} NMR spectrum, 3 J(,) =. z, 18, PC C 3 ). 19 NMR (8. Mz, [D 8 ]toluene, 300 K): δ = 5.6 (d, 3 J(,) = 3.5 z, 1), 10.5 ppm (d, 3 J(,) = 3.5 z, 1). 31 P{ 1 } NMR (11.5 Mz, [D 8 ]toluene, 300 K): δ = 0.0 (dtm, 1 J(Rh,P) = 119 z, J(P,P) = 38 z, 1P), 16. ppm (ddm, 1 J(Rh,P) = 155 z, J(P,P) = 38 z, P). or the NMR data of 1 see page 1. 16

17 Theoretical Methods The structure calculation of compound 3 was done using the Gaussian 09 (Revision C.01) program package 5 and the B3LYP functional. cc-pvtz basis sets were employed for all atoms except the carbon and hydrogen atoms of the ligands, which were described with cc-pvdz basis sets, and rhodium, which was described using a RECP with the associated cc-pvtz-pp basis set. 6 A frequency calculation was run to identify the obtained structure as a minimum (no negative eigenvalues). Energy was corrected for zero-point energy. xyz-coordinates for compound 3: Rh P P C C C C C C C C C C C C

18 N C C C C C Si O O O C C C C C

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