Synthesis and structures of fluorinated (β-diketiminato)rhodium complexes: Si-H activation of silanes at a carbonyl complex

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DOI:10.1002/ejic.201402087

Synthesis and Structures of Fluorinated (β-Diketiminato)-

rhodium Complexes: Si–H Activation of Silanes at a

Carbonyl Complex

Gregor Meier,^[a]Viktoria Steck,^[a]Beatrice Braun,^[a]Anna Eißler,^[a]

Roy Herrmann,^[a]Mike Ahrens,^[a]Reik Laubenstein,^[a]and

Thomas Braun*^[a]

Keywords: N ligands / Fluorinated ligands / Silicon / Silanes / Rhodium

The (β-ketiminato)rhodium complex [Rh{κ²-(N,O)-(tBu)(O)-

CCHC(tBu)N(C₆F₅)}(cod)] (1) [cod (1Z,5Z)-1,5-cyclooc-

NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a) with tertiary sil-

anes HSiR₃gave the (β-diketiminato)(hydrido)(silyl)rhodium

complexes [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}-

(H)(SiR₃)(CO)] (10a: R = Me; 11: R = Et; 12: R = iPr; 13: R =

Ph; 14: R = OMe; 15: R = OEt). When using an excess amount

of HSiMe₃the dihydridobis(silyl) complex [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)₂(SiMe₃)₂] (16) was formed

in addition to 10a.

=

tadiene] and (β-diketiminato)rhodium complexes [Rh{κ²-

(N,N)-(Ar)NC(Me)CHC(Me)N(Ar)}(L¹)(L²)] [2: Ar = C₆F₅, (L¹)-

(L²) = cod; 3: Ar = C₆F₅, L¹= L²= C₂H₄; 4: Ar = C₆F₅, L¹= L²

= CNtBu; 5: Ar = 2,6-MeC₆H₃, L¹= L²= CNtBu; 6a: Ar =

C₆F₅, L¹= L²= CO; 7a: Ar = C₆F₅, L¹= CO, L²= NCMe; 8a:

Ar = C₆F₅, L¹= CO, L²= PEt₃; 9a: Ar = C₆F₅, L¹= CO, L²

=

NH₃] were synthesized. Treatment of [Rh{κ²-(N,N)-(C₆F₅)-

reaction of [Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(R)CHC(R)-

N(2,6-iPr₂C₆H₃)}(phdi)] with X₂(X = Cl, Br, I) led to the

formation of trans-[Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(R)-

CHC(R)N(2,6-iPr₂C₆H₃)}(X)₂(phdi)] by oxidative addition

of the halogens.^[8]In the presence of [Rh{κ²-(N,N)-(2,6-

iPr₂C₆H₃)NC(Me)CHC(Me)N(2,6-iPr₂C₆H₃)}(coe)(N₂)],^[9]

the heterodehydrocoupling of secondary phosphines with

silanes was observed.^[10]For example, the coupling of

Ph₂PH and H₂SiPh₂yielded Ph₂PSiPh₂H and dihydrogen.

Mechanistic steps might include the formation of

the (hydrido)(silyl)rhodium complex [Rh{κ²-(N,N)-(2,6-

iPr₂C₆H₃)NC(Me)CHC(Me)N(2,6-iPr₂C₆H₃)}(H)(SiPh₂H)-

(PHPh₂)], which was synthesized in an independent reac-

tion.^[10]Recently, [Rh{κ²-(N,N)-(2,6-MeC₆H₃)NC(Me)-

CHC(Me)N(2,6-MeC₆H₃)}(coe)(N₂)] was applied for the

Si–H activation of HSiEt₃.^[11]In an initial step the dihyd-

ridobis(silyl)rhodium complex cis,trans-[Rh{κ²-(N,N)-(2,6-

MeC₆H₃)NC(Me)CHC(Me)N(2,6-MeC₆H₃)}(H)₂(SiEt₃)₂]

is formed. The latter is not stable in solution and quantita-

tively transforms into ethane and a rhodium complex, in

which one SiEt₂moiety is bridged to a benzylic carbon

atom of the β-diketiminato ligand.^[11]One step in the cou-

pling of HSiEt₃to the β-diketiminato ligand might include

the cyclometallation of a benzylic C–H bond of the aryl

substituent of the β-diketiminate.^[3,11]To avoid cyclometal-

lation reactions of the N-bound aryl rings, the choice of the

substituents of the β-diketiminato ligand might therefore be

critical. One option could be the use of perfluorinated

groups, because the corresponding ligands do not contain

Introduction

Transition-metal complexes supported by β-diketiminato

or β-ketiminato ligands have received increasing atten-

tion.^[1–3]The versatile electronic properties and steric de-

mands of β-diketiminates or β-ketiminates can be adjusted

by variation of the substituents in the ligand backbone or

at the nitrogen atoms to give access to transition-metal

compounds that can exhibit unusual geometries and/or low

coordination numbers.^[1–3]Hence, a variety of (β-diketimin-

ato)rhodium complexes^[4–12]have been developed. For

example, the complex [Rh{κ²-(N,N)-(2,6-Me₂C₆H₃)NC-

(Me)CHC(Me)N(2,6-Me₂C₆H₃)}(coe)] [coe = (Z)-cyclo-

octene] can be employed in the hydrogenation of olefins.^[4,5]

[Rh{κ²-(N,N)-(2,6-Me₂C₆H₃)NC(Me)CHC(Me)N(2,6-

Me₂C₆H₃)}(coe)(N₂)] was used in the P–P activation of

P₅Et₅or P₅Ph₅.^[6]The (β-diketiminato)rhodium complexes

[Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(R)CHC(R)N(2,6-

iPr₂C₆H₃)}(CO)₂] (R = CH₃, CF₃) can be transformed into

the rhodium compounds [Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)-

NC(R)CHC(R)N(2,6-iPr₂C₆H₃)}(phdi)] (phdi = 9,10-phen-

anthrenediimine) in the presence of N,NЈ-bis(trimethylsilyl)-

9,10-phenanthrenediimine and ONMe₃.^[7]The subsequent

[a] Humboldt-Universität zu Berlin,

Department of Chemistry,

Brook-Taylor-Straße 2, 12489 Berlin

E-mail: thomas.braun@chemie.hu-berlin.de

http://www2.hu-berlin.de/chemie/braun/

Supporting information for this article is available on the

WWW under http://dx.doi.org/10.1002/ejic.201402087.

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an aryl C–H bond.^[13]In addition, fluorinated ligands can

have a stabilizing influence that allows the detection or even

isolation of transition-metal complexes with unusual struc-

tural motifs.^[14]The β-diketimine (C₆F₅)NC(Me)CHC(Me)-

NH(C₆F₅) (17)^[15]might, therefore, be an interesting and

potent ligand precursor.^[16]Herein, we report the synthesis

and reactivity of a series of rhodium complexes that bear a

fluorinated β-diketiminato ligand as well as a fluorinated β-

ketiminato ligand. The reactivity of [Rh{κ²-(N,N)-(C₆F₅)-

NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a) towards ter-

tiary silanes was also studied.

Results and Discussion

Reaction of dipivaloylmethane with pentafluoroaniline

in the presence of para-toluenesulfonic acid (HOTs) at

111 °C led to the formation of the β-ketimine (tBu)(O)-

CCH₂C(tBu)N(C₆F₅) (18). Treatment of 18 with KH in

THF at –20 °C afforded dihydrogen and the β-ketiminate

[K{(tBu)(O)CCHC(tBu)N(C₆F₅)}] (19). In solution, com-

pound 19 is stable for several hours. The rhodium derivative

[Rh{κ²-(N,O)-(tBu)(O)CCHC(tBu)N(C₆F₅)}(cod)] (1) [cod

= (1Z,5Z)-1,5-cyclooctadiene] was obtained by the reaction

of 19 with [{Rh(μ-Cl)(cod)}₂] (Scheme 1).

Scheme 2. Formation of [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(cod)] (2) and [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CNtBu)₂] (4).

C=N stretching vibration, respectively. The structure of 18

in the solid state was determined by X-ray crystallography

(Figure 1). Selected bond lengths and angles are summa-

rized in Table 1. The C9–O1 and the C7–N1 distances

[1.206(3) and 1.277(3) Å] of the β-ketimine 18 are compar-

able to the data for other C=O or C=N double bonds,^[17]

the distances C7–C8 [1.508(3) Å] and C8–C9 [1.527(3) Å] in

the ligand backbone account for C–C single bonds. The

N1–C7–C8–C9 torsion angle in 18 is 77.8(3)°. In contrast,

the solid-state structure of (Me)(O)CCHC(Me)NH(C₆F₅)

shows a syn orientation of the C=O and the C–NH(C₆F₅)

unit, thus designating a β-aminoenone structure.^[18]

Scheme 1. Formation of (tBu)(O)CCH₂C(tBu)N(C₆F₅) (18) and

[Rh{κ²-(N,O)-(tBu)(O)CCHC(tBu)N(C₆F₅)}(cod)] (1).

Deprotonation of the β-diketimine (C₆F₅)NC(Me)CHC-

(Me)NH(C₆F₅) (17) with KH led to the formation of

[K{(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}] (20), which is stable

in solution for several hours. Reaction of 20 with [{Rh(μ-Cl)-

(cod)}₂] yielded [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(cod)] (2) (Scheme 2).

Figure 1. Molecular structure of (tBu)(O)CCH₂C(tBu)N(C₆F₅)

(18) (ORTEP, ellipsoids set at 50% probability).

The ¹H NMR spectrum of the β-ketimine 18 shows three

singlets at δ = 1.28, 1.54, and 2.79 ppm, which were as-

signed to the non-equivalent tBu groups and the methylene

bridge between the carbonyl and the imino function,

respectively. The ¹⁹F NMR spectrum of 18 displays three

signals at δ = –153.3, –165.9, and –166.9 ppm for the per-

fluorinated phenyl substituent. Resonances at δ = 207.2 and

183.9 ppm in the ¹³C{¹H} NMR spectrum can be attributed

to the carbonyl and the imino group. The solid-state IR

Table 1. Selected bond lengths [Å] and angles [°] for (tBu)(O)-

CCH₂C(tBu)N(C₆F₅) (18).

C9–O1

1.206(3)

1.277(3)

1.410(3)

1.526(3)

1.527(3)

1.508(3)

1.521(3)

122.4(2)

120.9(2)

C7–C8–C9

N1–C7–C8

112.79(19)

123.8(2)

119.3(2)

118.8(2)

116.9(2)

116.73(19)

77.8(3)

C7–N1

C1–N1

C9–C10

C8–C9

C7–C8

C7–C14

O1–C9–C10

O1–C9–C8

N1–C7–C14

C7–N1–C1

C8–C7–C14

C10–C9–C8

N1–C7–C8–C9

C8–C7–N1–C1

C7–C8–C9–O1

2.0(3)

–10.3(3)

spectrum (ATR) of 18 shows absorption bands at ν = 1710

˜

and 1637 cm^–1, which can be assigned to the C=O and

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The ¹⁹F NMR spectra of 19 and 20 each show three sig- Table 2. Selected bond lengths [Å] and angles [°] for [Rh{κ²-(N,O)-

(tBu)(O)CCHC(tBu)N(C₆F₅)}(cod)] (1).

nals at δ = –157.1, –171.5, and –180.7 ppm and δ = –156.0,

1

–168.3, and –174.3 ppm, respectively. The H NMR spec-

trum of 19 displays three singlets at δ = 5.46, 1.54, and

1.22 ppm, which were assigned to the methine proton and

the inequivalent tBu groups in the ligand backbone. The

methine proton and the methyl groups in the ligand back-

bone of 20 afforded two singlets at δ = 4.86 and 1.74 ppm.

Complexes 1 and 2 are soluble in benzene, toluene, or

THF, slightly soluble in hexane, pentane, or Et₂O, and are

inert to water, dioxygen, or dihydrogen. The ¹⁹F NMR

spectra feature three signals for the perfluorinated phenyl

substituent at δ = –144.6, –161.3, and –164.0 ppm, which

integrate in a ratio of 2:1:2 (for 1) and at δ = –147.8, –159.0,

and –162.9 ppm with an integral ratio of 2:1:2 (for 2). Three

N1–Rh1

O1–Rh1

C1–Rh1

C2–Rh1

C5–Rh1

C6–Rh1

C1–C2

2.1187(19)

2.0156(16)

2.104(2)

2.136(2)

2.123(2)

2.138(2)

1.400(4)

1.397(3)

1.347(3)

1.414(3)

1.267(3)

1.391(3)

C1–Rh1–C6

C1–Rh1–N1

O1–Rh1–C6

O1–Rh1–N1

81.73(9)

97.69(8)

84.07(8)

89.88(7)

127.57(15)

125.10(15)

114.02(14)

120.85(19)

125.6(2)

121.4(2)

–91.1(3)

–6.3(4)

C9–O1–Rh1

C11–N1–Rh1

C20–N1–Rh1

C11–N1–C20

O1–C9–C10

N1–C11–C10

C25–C20–N1–Rh1

C10–C9–O1–Rh1

C9–C10–C11–N1

C10–C11–N1–C20

C5–C6

C11–N1

C20–N1

C9–O1

C9–C10

C10–C11 1.402(3)

C9–C12 1.538(3)

C11–C16 1.566(3)

5.4(4)

177.2 (2)

1

singlet resonances in the H NMR spectrum of 1 at δ =

5.76, 1.13, and 0.94 ppm can be assigned to the methine

proton and the inequivalent tBu groups in the backbone of

the β-ketiminato ligand. In the ¹H NMR spectrum of 2, the

methine proton and the methyl groups in the ligand back-

bone cause two singlets at δ = 4.98 and 1.38 ppm, respec-

tively. Multiplets at δ = 4.57, 2.71, 2.21, and 1.49 ppm can

be attributed to the olefinic protons and the CH₂groups of

the cod ligand in 1.^[5]The cod ligand of complex 2 affords

resonance signals at δ = 3.31 ppm for the olefinic protons

and signals at δ = 1.96 and 1.38 ppm for the CH₂groups.^[5,9]

Table 3. Selected bond lengths [Å] and angles [°] for [Rh{κ²(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(cod)] (2).

Rh1–N1

Rh1–N2

Rh1–C18

Rh1–C22

Rh1–C23

Rh1–C19

C18–C19

C22–C23

N1–C1

2.090(2)

2.104(2)

2.133(2)

2.148(2)

2.162(2)

1.397(4)

1.390(4)

1.420(3)

1.335(3)

1.422(3)

1.338(3)

1.399(3)

1.388(3)

1.511(3)

C9–C16

1.513(3)

N2–Rh1–N1

N2–Rh1–C18

N1–Rh1–C22

N1–C7–C8

N1–C7–C17

C9–C8–C7

C9–N2–Rh1

C7–N1–Rh1

N1–C7–C8–C9

C1–N1–C7–C8

C2–C1–N1–C7

Rh1–N1–C7–C8

88.40(8)

91.33(9)

93.86(9)

124.3(2)

120.3(2)

129.0(2)

125.81(16)

124.41(16)

6.48(12)

–172.16(12)

96.79(14)

13.3(2)

The structures of 1 and of 2 in the solid state were deter- N1–C7

N2–C10

mined by X-ray crystallography (Figure 2). Selected bond

N2–C9

lengths and angles are summarized in Tables 2 and 3.

C7–C8

C8–C9

C7–C17

almost planar π systems.^[19]In both compounds the per-

fluorinated aryl substituents are to some extent in an or-

thogonal orientation to the ligand backbone, which is

shown by the angles C25–C20–N1–Rh1 of –91.1(3)° in

complex 1 and C2–C1–N1–C7 of 96.79(14)° in 2.

The ethylene complex [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(C₂H₄)₂] (3) can be synthesized by add-

ing 20 to a solution of [{Rh(μ-Cl)(C₂H₄)₂}₂]. The ¹H NMR

spectrum of 3 displays resonances at δ = 2.45 and 1.73 ppm,

which can be attributed to the ethylene ligands. The

¹³C{¹H} NMR spectrum features a doublet at δ = 61.5 ppm

for the carbon atoms of the ethylene ligands with a rho-

dium–carbon coupling constant of J_Rh,C= 12.4 Hz. The

¹⁹F NMR spectrum of 3 reveals three signals for both per-

fluorinated phenyl substituents at δ = –147.2, –158.2, and

Figure 2. Molecular structures of [Rh{κ²-(N,O)-(tBu)(O)-

CCHC(tBu)N(C₆F₅)}(cod)] (1) (left) and [Rh{κ²(N,N)-(C₆F₅)-

NC(Me)CHC(Me)N(C₆F₅)}(cod)] (2) (ORTEP, ellipsoids set at

50% probability).

If the cod ligand is considered to be a bidentate ligand –162.9 ppm with an integral ratio of 2:1:2. In the liquid

that occupies two coordination sites, both structures are ap- injection field desorption ionization time-of-flight (LIFDI

proximately square-planar. The O1–Rh1–N1 angle of 1 is TOF) mass spectrum, a peak with m/z = 588.2 can be at-

89.88(7)°. The N1–Rh1 and the O1–Rh1 distances in 1, tributed to the molecule ion [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

Rh1–N1 and Rh1–N2 in complex 2, as well as the average CHC(Me)N(C₆F₅)}(C₂H₄)₂]⁺. Complex 3 can be stored for

Rh–C_coddistances (1: 2.125 Å; 2: 2.144 Å) are in good some days under ethylene at –30 °C but decomposes within

agreement with the separations in related complexes.^[5,9,19]hours at room temperature.

The distances in the backbones of the fluorinated ligands

The formal oxidation state of metal centers in transition-

as well as the small torsion angles [1: C9–C10–C11–N1 metal complexes that contain π-accepting ligands such as

5.4(4)°; 2: N1–C7–C8–C9 6.48(12)°] suggest the presence of carbonyl^{[7,12a,20,21]}or isocyanido ligands^[22–24]can be esti-

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mated by characteristic absorption bands of these π-ac- Table 4. Selected bond lengths [Å] and angles [°] for [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CNtBu)₂] (4).

ceptor ligands in the IR or Raman spectra. The use of such

ligands might therefore provide a helpful tool to obtain in-

formation on the electronic properties of the metal center.

Treatment of [{Rh(μ-Cl)(coe)₂}₂] with 20 followed by ad-

dition of CNtBu led to the formation of [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CNtBu)₂] (4) (Scheme 2).

The solid-state IR spectrum of 4 shows three absorption

Rh1–N1

Rh1–N2

Rh1–C18

Rh1–C23

C18–N3

C23–N4

C1–C2

N1–C1

N1–C6

N2–C3

2.0738(19)

2.0671(18)

1.893(2)

1.892(3)

1.154(3)

1.163(3)

1.397(3)

1.327(3)

1.420(3)

1.327(3)

1.416(3)

1.455(3)

1.443(4)

C2–C3

1.396(3)

N1–Rh1–N2

N2–Rh1–C18

N1–Rh1–C23

C18–Rh1–C23

C1–C2–C3

Rh1–C18–N3

Rh1–C23–N4

N1–C1–C2–C3

C6–N1–C1–C2

C7–C6–N1–C1

88.40(7)

176.36(10)

176.09(10)

84.92(10)

128.3(2)

177.6(2)

176.6(2)

6.1(5)

bands at ν = 2137, 2094, and 2064 cm^–1for two CNtBu

˜

ligands at a rhodium(I) complex.^[22–24]Spectra measured in

toluene and THF also reveal three bands at ν = 2137, 2095,

˜

N2–C12

N3–C19

N4–C24

–173.1(3)

–86.3(3)

and 2061 cm^–1(toluene) and at ν = 2139, 2096, and

˜

2061 cm^–1(THF). However, DFT calculations to model the

IR spectrum of 4 in the gas phase show only two absorption

bands at ν = 2189 and 2133 cm^–1(B3LYP/cc-pvdz). The

˜

tion bands at ν = 2140, 2103, and 2068 cm^–1for two CNtBu

˜

occurrence of three isocyanide bands might be due to inter-

molecular interactions in the liquid and in the solid state,

which lower the symmetry of the compound relative to the

isolated gaseous phase.^[24d,24e]The presence of three absorp-

tion bands in the IR spectra of diisonitrile complexes has

been documented in the literature.^[24]The ¹³C{¹H} NMR

spectrum exhibits an unusually high-field-shifted^[22]doublet

resonance for the rhodium-bound carbon atoms at δ =

147.8 ppm with a rhodium–carbon coupling constant of

¹J_Rh,C= 65.1 Hz. The structure of 4 in the solid state was

determined by X-ray crystallography (Figure 3); selected

bond lengths and angles are summarized in Table 4. The

rhodium atom in 4 exhibits again a square-planar coordina-

tion sphere. The rhodium–carbon distances are 1.893(2)

and 1.893(3) Å, and the carbon–nitrogen distances in the

isocyanido ligands are 1.155(3) and 1.161(3) Å. These val-

ues are comparable to the data in other isocyanide com-

plexes.^[22–24]The rhodium isocyanide units exhibit angles of

Rh1–C18–N3 177.5(2)° and Rh1–C23–N4 176.6(2)°.

ligands in the IR spectrum (ATR).^[22–24]The ¹³C{¹H}-

NMR spectrum features a doublet resonance signal at δ =

150.5 ppm with a rhodium–carbon coupling constant of

¹J_Rh,C= 63.0 Hz. The structure of 5 in the solid state was

also determined by X-ray crystallography (Figure 4); se-

lected bond lengths and angles are summarized in Table 5.

The distances Rh1–N1 [2.0727(13) Å] and Rh1–N2

[2.0672(14) Å] in 5 are comparable to those found in 4.

Figure 4. Molecular structure of [Rh{κ²(N,N)-(2,6-Me₂C₆H₃)-

NC(Me)CHC(Me)N(2,6-Me₂C₆H₃)}(CNtBu)₂] (5) (ORTEP, ellip-

soids set at 50% probability).

Table 5. Selected bond lengths [Å] and angles [°] for [Rh{κ²(N,N)-

(2,6-Me₂C₆H₃)NC(Me)CHC(Me)N(2,6-Me₂C₆H₃)}(CNtBu)₂] (5).

Rh1–N1

Rh1–N2

Rh1–C22

Rh1–C27

C22–N3

C27–N4

C1–C2

N1–C1

N1–C14

N2–C3

2.0727(13)

2.0672(14)

1.8951(17)

1.9048(17)

1.158(2)

1.399(2)

1.328(2)

1.435(2)

1.325(2)

1.435(2)

1.450(2)

1.454(2)

C2–C3

1.397(2)

N1–Rh1–N2

N2–Rh1–C22

N1–Rh1–C27

C22–Rh1–C27

C1–C2–C3

Rh1–C22–N3

Rh1–C27–N4

N1–C1–C2–C3

C4–N2–C3–C2

C5–C4–N2–C3

90.38(5)

176.35(6)

176.40(6)

84.70(7)

128.86(16)

175.50(15)

175.52(15)

5.76(28)

Figure 3. Molecular structure of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(CNtBu)₂] (4) (ORTEP, ellipsoids set at 50%

probability).

Comparable structural and spectroscopic data can be

found for the non-fluorinated complex [Rh{κ²(N,N)-(2,6-

Me₂C₆H₃)N-C(Me)CHC(Me)N(2,6-Me₂C₆H₃)}(CNtBu)₂]

(5). Complex 5 is accessible by treatment of [{Rh(μ-Cl)-

(coe)₂}₂] with [Li{(2,6-Me₂C₆H₃)NC(Me)CHC(Me)N(2,6-

Me₂C₆H₃)}] followed by the addition of CNtBu. The pres-

N2–C4

N3–C23

N4–C28

173.92(17)

91.60(11)

Treatment of the dinuclear complex [{Rh(μ-Cl)(CO)₂}₂]

ence of a rhodium(I) complex is again evidenced by absorp- with 20 led to the formation of [Rh{κ²(N,N)-(C₆F₅)NC-

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(Me)CHC(Me)N(C₆F₅)}(CO)₂] (6a) (Scheme 3). The isoto- and 1.124(3) Å] of the carbonyl ligands are in accordance

pologue [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}- with the data for (carbonyl)transition-metal complexes^[20,21]

(¹³CO)₂] (6b) is available in a similar fashion from [{Rh(μ- {e.g.,

[Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(CH₃)CHC(CH₃)-

Cl)(¹³CO)₂}₂]. In addition, 2,3,4,5,6-pentafluoro-N-[(Z)- N(2,6-iPr₂C₆H₃)}(CO)₂], 1.1358(18) and 1.1365(17) Å}.^[7]

6,7,8,9-tetrafluoro-2-methyl-1H-benzo[b]azepine-4(5H)-ylid-

ene]benzeneamine (22) can be isolated as a byproduct (see

the Supporting Information). The presence of a rhodium(I)

complex is evidenced by two characteristic absorption

bands at ν = 2070 and 2020 cm^–1in the IR spectrum (ATR)

˜

of 6a, which can be assigned to the symmetric and asym-

metric CO stretching vibration of the carbonyl li-

gands.^{[7,12a,20,21]}For 6b, these bands shift to ν = 2022 and

˜

1975 cm^–1, respectively. The structurally related complex

[Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(CF₃)CHC(CF₃)N(2,6-

iPr₂C₆H₃)}(CO)₂] bears electron-withdrawing CF₃groups

in the backbone of the β-diketiminato ligand and shows

absorption bands at ν = 2078 and 2020 cm^–1,^[7]which are

˜

in the same range as for 6a. In contrast to these fluorinated

β-diketiminato complexes, [Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC-

Figure 5. Molecular structure of [Rh{κ²(N,N)-(C₆F₅)NC(Me)-

(CH₃)CHC(CH₃)N(2,6-iPr₂C₆H₃)}(CO)₂] exhibits bands at

CHC(Me)N(C₆F₅)}(CO)₂] (6a) (ORTEP, ellipsoids set at 50%

probability).

ν = 2053 and 1988 cm^–1.^[7]Thus, the perfluorinated aryl

˜

groups in 6a decrease the electron density at the rhodium

center in comparison to non-fluorinated complexes. A

doublet signal at δ = 184.4 ppm in the ¹³C{¹H} NMR spec-

Table 6. Selected bond lengths [Å] and angles [°] for [Rh{κ²(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)₂] (6a).

trum with a rhodium–carbon coupling constant of ¹J_Rh,C

=

Rh1–N1

Rh1–N2

Rh1–C1

Rh1–C2

C1–O1

C2–O2

N1–C3

N1–C8

N2–C5

N2–C14

C3–C4

2.0565(18)

2.0517(17)

1.871(3)

1.864(3)

1.129(3)

1.124(3)

1.333(3)

1.422(3)

1.332(3)

1.423(3)

1.399(3)

1.398(3)

N1–Rh1–N2

N2–Rh1–C1

N1–Rh1–C2

C1–Rh1–C2

C3–C4–C5

Rh1–C1–O1

Rh1–C2–O2

N1–C3–C4–C5

C1–Rh1–N1–C8

C15–C14–N2–C5

88.91(7)

178.08(9)

178.77(10)

85.98(11)

128.3(2)

178.4(2)

179.0(3)

–3.4(4)

66.6 Hz is assigned to the carbonyl ligands in 6b. The other

NMR spectroscopic data of 6a and 6b are as expected.

4.50(17)

–86.9(2)

C4–C5

Complexes 4, 5, and 6a are inert toward dioxygen or

water. However, treatment of 6a with ONMe₃in the pres-

ence of acetonitrile gave NMe₃, CO₂, and [Rh{κ²-(N,N)-

(2,6-MeC₆H₃)NC(Me)CHC(Me)N(2,6-MeC₆H₃)}(CO)-

(NCMe)] (7a) (Scheme 3). The ¹³C-labeled isotopomer

[Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)-

(NCMe)] (7b) is available from 6b in a similar fashion. The

presence of a rhodium(I) complex 6a is evidenced by an

Scheme 3. Formation of [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CO)₂] (6a) and [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CO)(NCMe)] (7a).

absorption band in the solid-state IR spectrum of 7a at ν =

˜

1992 cm^–1, which can be attributed to the stretching vi-

bration of the carbonyl ligand.^{[7,12a,20,21]}This band shifts

The structure of 6a in the solid state was also determined to ν = 1946 cm^–1for the ¹³C-labeled complex 7b. A weak

˜

by X-ray crystallography (Figure 5). Selected bond lengths absorption band at ν = 2283 cm^–1can be assigned to the

˜

and angles are summarized in Table 6. In the solid state the NCMe ligand. For comparison, the cationic compound

rhodium atom in 6a adopts a square-planar coordination [Rh(CO)₂(NCMe)₂]⁺shows two bands at ν = 2330 and

˜

sphere. The Rh1–N1 [2.0565(18) Å] and Rh1–N2 2300 cm^–1for the NCMe ligand. In (acetonitrile)rhodi-

[2.0517(17) Å] distances in 6a are slightly shortened relative um(III) complexes, stretching vibrations were found at ν =

˜

to 2 or 4 but are in good agreement with the distances 2360 cm^–1.^[25]The lower energy of the absorption band that

found in [Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(CH₃)CHC(CH₃)- is assigned to the stretching vibration of the carbonyl ligand

N(2,6-iPr₂C₆H₃)}(CO)₂] [2.0514(11) and 2.0491(11) Å].^[7]in 7a (ν = 1992 cm^–1) relative to 6a (ν = 2070 and

˜

Both the rhodium–carbon distances [1.871(3) and 2020 cm^–1) and the downfield shift of the ¹³C{¹H} reso-

1.864(3) Å] and the carbon–oxygen bond lengths [1.129(3) nance signal for the CO carbon atom (δ = 188.8 ppm for

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7a relative to δ = 184.4 ppm for 6a) indicate a stronger π amount of ONMe₃was also not observed. This observa-

backbonding in 7a.^[7,20,21,26]In contrast to complex 6a, the tions are in contrast to the reactivity of [Rh{κ²-(N,N)-

¹⁹F NMR spectrum of 7a displays six resonance signals, (2,6-iPr₂C₆H₃)NC(Me)CHC(Me)N(2,6-iPr₂C₆H₃)}(CO)₂]^[7]

which is a result of the different ligands in the trans position However, we were able to identify [Rh{κ²(N,N)-(C₆F₅)-

to the β-diketiminato ligand. The ¹³C{¹H} NMR spectrum NC(Me)CHC(Me)N(C₆F₅)}(CO)(NMe₃)] (23) by using 1,2-

of 7b features a doublet resonance for the carbonyl ligand difluorobenzene as the solvent instead of acetonitrile. Com-

at δ = 188.8 ppm with a rhodium–carbon coupling constant plex 23 is presumably an intermediate in the formation of

1

of J_Rh,C= 71.5 Hz.

7a and is the initial product formed prior to the coordina-

Figure 6 shows the solid-state structure of 7a, which was tion of the acetonitrile to give 7a. Complex 23 could only

determined by X-ray crystallography. Selected bond lengths be characterized by NMR spectroscopy in solution due to

and angles are summarized in Table 7. Compound 7a decomposition upon evaporation of the solvent 1,2-

adopts a square-planar coordination sphere. The Rh1–N1 C₆H₄F₂. However, an absorption band for the CO stretch-

distance of 2.019(3) Å is shortened relative to Rh1–N2 ing vibration at ν = 1954 cm^–1in the IR spectrum of 23

˜

[2.059(12) Å]. The latter moiety is located in the trans posi- (ATR), which was measured after slow evaporation of the

tion to the carbonyl ligand. This observation reflects the solvent at ambient pressure, gives evidence for the presence

stronger π-acceptor properties of the CO ligand relative to of a rhodium(I) complex.

the coordinated acetonitrile. The Rh1–C20 distance

Acetonitrile ligands are often bound labile and can easily

amounts to 1.825(3) Å, and comparable separations can be be replaced by other ligands.^[27]Accordingly, exposure of a

found in other (carbonyl)transition-metal complexes.^[7,20,21]solution of 7a to carbon monoxide led to the formation of

The CO distance in the carbonyl ligand is with 1.152(4) Å 6a. Treatment of 7a with PEt₃or NH₃gave the complexes

slightly longer than those found in 6a (average of 1.127 Å) [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

or [Rh{κ²-(N,N)-(2,6-iPr₂C₆H₃)NC(Me)CHC(Me)N(2,6- (PEt₃)] (8a) or [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

iPr₂C₆H₃)}(CO)₂]^[7](average 1.136 Å).

N(C₆F₅)}(CO)(NH₃)] (9a), respectively (Scheme 4). The

¹³C-labeled isotopomers [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(¹³CO)(PEt₃)] (8b) or [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)(NH₃)] (9b) are

available from 7b in a similar fashion. The complexes 8a

and 9a could only be characterized in solution owing to

decomposition upon evaporation of the solvent. We did not

observe any oxidative addition of an N–H bond in 9a as

was observed for other rhodium and iridium complexes.^[28]

Figure 6. Molecular structure of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a) (ORTEP, ellipsoids set at

50% probability).

Table 7. Selected bond lengths [Å] and angles [°] for [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a).

Rh1–N1

Rh1–N2

Rh1–N3

Rh1–C20

O1–C20

N3–C18

C18–C19

N1–C1

N2–C10

N1–C7

N2–C9

C7–C8

C8–C9

2.019(3)

2.059(2)

2.011(3)

1.825(3)

1.152(4)

1.142(4)

1.449(5)

1.423(4)

1.418(4)

1.340(4)

1.342(4)

1.399(4)

1.385(5)

1.496(5)

N1–Rh1–N2

C20–Rh1–N3

N1–Rh1–N3

C20–Rh1–N2

C1–N1–Rh1

O1–C20–Rh1

Rh1–N3–C18

N3–C18–C19

C9–N2–C10–C15

C20–Rh1–N3–C18

N1–C7–C8–C9

Rh1–N1–C7–C8

89.95(10)

86.14(13)

174.64(10)

176.47(13)

115.1(2)

176.3(3)

170.0(3)

178.2(3)

91.2(4)

Scheme 4. Reactivity of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CO)(NCMe)] (7a) towards CO, PEt₃, NH₃, and HSiR₃

(R = Me, Et, iPr, Ph, OMe, OEt).

–42.3(17)

6.0(5)

6.4(5)

The ³¹P{¹H} NMR spectrum of 8a displays a doublet at

δ = 21.7 ppm with a rhodium–phosphorus coupling con-

1

C7–C17

stant of J_Rh,P= 125.8 Hz consistent with a phosphine li-

gand at a rhodium(I) center.^[29]For 8b the ³¹P{¹H} NMR

Complex 7a shows no reaction with ONMe₃, and a reac- spectrum reveals a carbon–phosphorus coupling constant

2

tion of both CO ligands in 6a in the presence of an excess of J_P,C= 17.5 Hz, which indicates a cis geometry of the

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1

carbonyl and phosphine ligand.^[30]A signal at δ = formation of the dihydridobis(silyl) complex 16. In the H

191.9 ppm in the ¹³C{¹H} NMR spectrum of 8b can be NMR spectra a singlet at δ = 0.58 ppm can be attributed

attributed to the carbon atom of the carbonyl li- to free acetonitrile.^[32]When the ¹³C-labeled complex 7b is

gand.^[7,20,21,26]The presence of the rhodium(I) complex 8a used as a starting compound, a resonance signal at δ =

is evidenced by an absorption band at ν = 1962 cm^–1, which 181.5 ppm emerged in the ¹³C{¹H} NMR spectrum simul-

˜

can be assigned to the stretching vibration of the CO li- taneously with the formation of 16. The signal can be at-

gand.^{[7,12a,20,21]}This band shifts to ν = 1914 cm^–1for the tributed to ¹³CO.^[33]Treatment of the reaction mixture that

˜

¹³C-labeled complex 8b. The IR spectrum (ATR) of 9a consisted of 10a and 16 with an excess amount of CO led

[34]

shows an absorption band at ν = 1956 cm^–1for the CO to the formation of HSiMe₃and 6a.

˜

ligand, which shifts to ν = 1910 cm^–1for 9b. Bands at ν =

The ¹H NMR spectrum of 10a displays resonance signals

˜

3372 and 3364 cm^–1can be attributed to N–H stretching at δ = 0.31 and –12.34 ppm, which can be assigned to the

1

vibrations of the ammine ligand. The H NMR spectrum SiMe₃ligand and the hydrido ligand, respectively. The

of 9a reveals a resonance for the NH₃ligand at δ = doublet signal for the latter shows a rhodium–hydrogen

1

0.62 ppm. A doublet resonance signal for the CO carbon coupling constant of J_Rh,H= 22.2 Hz. The signal for the

atom can be found at δ = 190.5 ppm in the ¹³C{¹H} NMR hydrido ligand in the ¹³C-labeled complex 10b reveals a car-

2

spectrum of 9b.

bon–hydrogen coupling constant of J_C,H= 9.5 Hz, which

Reactions of the (β-diketiminato)rhodium complex 7a is characteristic of a mutual cis geometry of the hydrido and

with silanes HSiR₃(R = Me, Et, iPr, Ph, OMe, OEt) led the carbonyl ligand.^[30]A doublet resonance in the ¹³C{¹H}

to the formation of the (hydrido)(silyl)rhodium complexes NMR spectrum of 10b at δ = 188.2 ppm with a rhodium–

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)

carbon coupling constant of ¹J_Rh,C= 67.1 Hz can be attrib-

N(C₆F₅)}(H)(SiR₃)(CO)] (10a: R = Me; 11: R = Et; 12: R uted to the carbon atom of the CO ligand. The presence of

= iPr; 13: R = Ph; 14: R = OMe; 15: R = OEt) by oxidative a rhodium(III) complex is again evidenced by an absorption

addition (Scheme 4). The (hydrido)(silyl)rhodium com- band in the IR spectrum (ATR) of 10a at

ν =

˜

plexes could not be isolated and were characterized by 2072 cm^–1.^{[7,12a,20,21]}This band shifts to ν = 2022 cm^–1for

˜

NMR spectroscopy only. In each case the ¹H NMR spectra the ¹³C-labeled complex 10b. Absorption bands at ν = 2025

˜

show a characteristic doublet signal for the hydrido li- and 2017 cm^–1can tentatively be assigned to stretching vi-

gand^[11,31]between δ = –11 and –13 ppm with a rhodium– brations of the Rh–H moieties of 10a and 16.^[31]The spec-

hydrogen coupling constant (¹J_Rh,H) between 19 and 24 Hz. troscopic data of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

An excess amount of HSiMe₃led to full conversion of N(C₆F₅)}(H)₂(SiMe₃)₂] (16) indicate the presence of equiva-

7a after 5 h and to the formation of [Rh{κ²-(N,N)-(C₆F₅)- lent pentafluorophenyl groups. The ¹⁹F NMR spectrum of

NC(Me)CHC(Me)N(C₆F₅)}(H)(SiMe₃)(CO)] (10a) as well 16 displays three signals at δ = –147.6, –161.6, and

1

as of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)₂- –163.4 ppm. The resonance signals in the H NMR spec-

(SiMe₃)₂] (16) (Scheme 5). We were not able to separate trum at δ = 0.29 and –14.50 ppm reveal the presence of

compounds 10a and 16, in part because of the incipient the SiMe₃ligands and the hydrido ligands. The latter signal

formation of small amounts of (C₆F₅)NC(Me)CHC(Me)- appears as a doublet with a rhodium–hydrogen coupling of

NH(C₆F₅) (17). Integration of the ¹H and ¹⁹F NMR signals ¹J_Rh,H= 23.4 Hz. The resonance correlates to a signal for

shows for 10a/16/17 a ratio of 12:1:1 after 4 h. By increasing the SiMe₃ligands at δ = 35.5 ppm in the ²⁹Si domain in an

the reaction time to 8 h, the product ratio 10a/16/17 ¹H,²⁹Si heteronuclear multiple-bond correlation (HMBC)

changes to 5:2:3. Treatment of a solution of 7b with NMR spectrum (Figure 7).^[11,31]The NMR spectroscopic

HSiMe₃gave the ¹³C-labeled complex [Rh{κ²-(N,N)-(C₆F₅)- data are in accordance with those found for other bis(silyl)-

NC(Me)CHC(Me)N(C₆F₅)}(H)(SiMe₃)(¹³CO)] (10b) and rhodium(V) complexes, in which the silyl ligands are in a

again the dihydridobis(silyl) complex 16.

mutual trans orientation.^[35]

DFT calculations were performed to model conceivable

configurations of 10a and 16. They revealed that the isomer

of

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)-

(SiMe₃)(CO)] (10a), which exhibits a mutual cis orientation

of the hydrido and the carbonyl ligands and in which the

silyl ligand occupies the apical position in a square-pyrami-

dal complex, is the only isomer that converged to a stable

structure (Figure 8; see the Supporting Information). Such

a geometry with the silyl ligand in the apical position can

also be found for [Rh{κ²-(N,N)-3,5-diphenyl-2-(2-pyridyl)-

pyrrolido}(H)(SiPh₃)(PPh₃)]^[35]and trans-[Os(SiR₃)(Cl)-

(CO)(PPh₃)₂]^[36a](R = F, Cl, OH, Me). The calculations

also revealed that the dihydridobis(silyl) isomer 16 with a

mutual cis orientation of the hydrido ligands is again the

Scheme 5. Formation of Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(H)(SiMe₃)(CO) (10a) and [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(H)₂(SiMe₃)₂] (16).

The reaction of 7a with HSiMe₃can be monitored by only isomer that converged to a stable structure (Si–Rh–Si

NMR spectroscopy. Initially, 10a is formed, followed by the angle 106.9°; Figure 8). There is no indication of the pres-

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Conclusion

We have described the synthesis of new (β-ketiminato)-

and (β-diketiminato)rhodium complexes that bear ligands

with perfluorinated aryl groups. Stable carbonyl and iso-

cyanide complexes with the β-diketiminato backbone were

prepared. Treatment of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC-

(Me)N(C₆F₅)}(CO)(NCMe)] (7a) with HSiMe₃gave the (β-

diketiminato)(hydrido)(silyl)rhodium complexes [Rh{κ²-

(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)(SiMe₃)(CO)]

(10a)

and

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N-

(C₆F₅)}(H)₂(SiMe₃)₂] (16). An Si–C coupling reaction be-

tween the silyl ligand and the β-diketiminato ligand in 10a

or 16 was not observed because of the presence of the

fluorinated β-diketiminato ligand {(C₆F₅)NC(Me)CHC-

(Me)N(C₆F₅)}.

1

Figure 7. Part of the H,²⁹Si HMBC NMR spectrum showing the

resonance signal assigned to [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(H)₂(SiMe₃)₂] (16).

Experimental Section

ence of a non-classical structure (i.e., an interaction be-

tween a silyl and a hydrido ligand).^[37]Note that often

bis(silyl) complexes show a mutual cis orientation of the

SiR₃ligands,^[36,38]but trans arrangements are also

General Methods and Instrumentation: All experiments were per-

formed with a Schlenk line under argon or an argon-filled glovebox

with dioxygen levels below 10 ppm. All solvents were purified and

dried by conventional methods and distilled under argon. Dipiva-

known^[31,35]{e.g., in cis,trans-[Rh{κ²-(N,N)-(2,6-MeC₆H₃)- loyl methane, CNtBu, 2,4-pentanedione, HSiPh₃, HSi(iPr)₃, HSi-

(OMe)₃, HSi(OEt)₃, HSiEt₃, Na₂CO₃, MgSO₄, ONMe₃, ¹³CO, and

HNiPr₂were obtained from Aldrich; para-toluenesulfonic acid,

nBuLi, and 2,6-dimethylaniline were purchased from Acros Or-

ganics; KH, pentafluoroaniline, and HSiMe₃were purchased from

ABCR; CO was obtained from BASF. PEt₃,^[39](C₆F₅)NC(Me)-

CHC(Me)NH(C₆F₅) (17),^[15](2,6-Me₂C₆H₃)NC(Me)CHC(Me)-

NC(Me)CHC(Me)N(2,6-MeC₆H₃)}(H)₂(SiEt₃)₂]}.^[11]

NH(2,6-Me₂C₆H₃)

(21),^[40]

[{Rh(μ-Cl)(cod)}₂],^[41]

[{Rh(μ-

Cl)(C₂H₄)₂}₂],^[42][{Rh(μ-Cl)(coe)₂}₂],^[43][{Rh(μ-Cl)(CO)₂}₂], and

[{Rh(μ-Cl)(¹³CO)₂}₂]^[44]were prepared according to the literature.

The NMR spectra were recorded with a Bruker DPX 300 or a

Bruker AV III 300 spectrometer. Chemical shifts are reported in

ppm. ¹H NMR spectroscopic chemical shifts were referenced to re-

sidual C₆D₅H at δ = 7.15 ppm or to residual [D₇]THF at δ =

3.58 ppm. ¹³C{¹H} NMR spectroscopic chemical shifts were refer-

enced to C₆D₆at δ = 128.06 ppm or to [D₈]THF at δ = 67.21 ppm.

The ³¹P{¹H}, ¹⁹F, and ²⁹Si NMR spectra were referenced externally

to H₃PO₃at δ = 0.0 ppm, to C₆F₆at δ = –162.9 ppm, and to SiMe₄

at δ = 0.0 ppm, respectively. Microanalyses were performed with a

HEKAtech Euro EA Elemental Analyzer. Infrared spectra were

recorded with a Bruker Vertex 70 spectrometer equipped with an

ATR unit (diamond), and Raman spectra were recorded with a

Bruker Vertex 70 with RAM II (Nd:YAG laser; 1064 nm). GC mass

spectra were recorded with an Agilent 6890N gas chromatograph

and an Agilent 5973 Network mass selective detector. The ESI

mass spectra were recorded with an Esquire 3000 ion-trap mass

spectrometer (Bruker), and LIFDI TOF mass spectra were re-

corded with a Micromass Q-ToF-2 mass spectrometer that was

equipped with a LIFDI 700 ion source (Linden CMS).

Figure 8. DFT/B3LYP-optimized geometries of [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)(SiMe₃)(CO)] (10a) (top)

and [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)₂(SiMe₃)₂]

(16) (bottom). Ligand hydrogen atoms are omitted for clarity.

(tBu)(O)CCH₂C(tBu)N(C₆F₅) (18): A solution of dipivaloyl meth-

ane (0.888 g, 4.8 mmol, 0.99 mL) in toluene (45 mL) was treated

with pentafluoroaniline (1.830 g, 10.0 mmol) and para-toluenesul-

fonic acid (0.899 g, 4.7 mmol). The reaction mixture was heated

under reflux conditions with a Dean–Stark apparatus for 48 h.

Subsequently, most of the solvent was distilled off. After the solu-

tion had cooled to room temperature, volatile compounds were re-

moved under vacuum. The obtained solid was dissolved in diethyl

ether (25 mL) and water (25 mL). Sodium carbonate (1.098 g,

We did not observe a reaction of the silyl ligand with the

β-diketiminato ligand in 10a or 16, as was described for

cis,trans-[Rh{κ²-(N,N)-(2,6-MeC₆H₃)NC(Me)CHC(Me)N-

(2,6-MeC₆H₃)}(H)₂(SiEt₃)₂].^[11]Such a degradation reac-

tion can be avoided by the use of the highly fluorinated β-

diketimine 17.

Eur. J. Inorg. Chem. 2014, 2793–2808

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10.36 mmol) was added, and the solution was stirred at room tem-

perature for 1.5 h. The aqueous layer was extracted two times each

with Et₂O (15 mL), and the combined organic layers were dried

with MgSO₄. The solvent was removed under vacuum. At –60 °C,

the residue was washed with a small amount of hexane. The color-

less solid was dissolved in hexane at room temperature, and the

solution was stored at –30 °C. (tBu)(O)CCH₂C(tBu)N(C₆F₅) (18)

was isolated as colorless crystalline solid. Yield: 1.111 g (4.2 mmol,

87%). C₁₇H₂₀F₅NO (349.34): calcd. C 58.45, H 5.77, N 4.01; found

propylamide (62 mg, 0.6 mmol) were treated with hexane (4 mL)

and Et₂O (4 mL) at room temperature. After 30 min, the orange

solution was transferred at –30 °C through a PTFE cannula to a

solution of [{Rh(μ-Cl)(cod)}₂] (108 mg, 0.2 mmol) in Et₂O (5 mL).

The mixture was stirred at –30 °C for 1.5 h. Subsequently, Et₂O

(4 mL) and THF (5 mL) were added and stirred at room tempera-

ture for 3 h. The solution turned brownish yellow. The volatile com-

pounds were removed under vacuum, and the residue was extracted

two times each with toluene (5 mL). After removal of the solvent

from the combined extracts under vacuum, the resulting solid was

C 59.10, H 6.05, N 4.53. IR (ATR): ν = 1710 (m, C=O), 1637 (m,

˜

C=N) cm^–1. ¹H NMR (300.1 MHz, C₆D₆, 25 °C): δ = 3.24 (s, 2 H, extracted two times each with hexane (6 mL). Concentration of the

CH₂), 1.13 [s, 9 H, C(CH₃)₃], 0.60 [s, 9 H, C(CH₃)₃] ppm. ¹H NMR

(300.1 MHz, THF/C₆D₆capillary, 25 °C): δ = 2.79 (s, 2 H, CH₂),

1.28 [s, 9 H, C(CH₃)₃], 1.54 [s, 9 H, C(CH₃)₃] ppm. ¹³C{¹H} NMR

(75.5 MHz, C₆D₆, 25 °C): δ = 207.2 [s, CO or CN(C₆F₅)], 183.9 [s,

combined hexane phases under vacuum yielded [Rh{κ²(N,O)-

(tBu)(O)CCHC(tBu)N(C₆F₅)}(cod)] (1) as a pale yellow solid.

Yield: 99 mg (0.2 mmol, 81%). C₂₅H₃₁F₅NORh (559.42): calcd. C

53.68, H 5.59, N 2.50; found C 53.32, H 5.89, N 2.12. ¹H NMR

(300.1 MHz, C₆D₆, 25 °C): δ = 5.76 (s, 1 H, CH), 4.57 (br. s, 2 H,

cod-CH), 2.71 (br. s, 2 H, cod-CH), 2.12 (m, 4 H, cod-CH₂), 1.49

(m, 4 H, cod-CH₂), 1.13 [s, 9 H, C(CH₃)₃], 0.94 [s, 9 H, C(CH₃)₃]

1

CO or CN(C₆F₅)], 138.2 (dm, J_C,F= 237.3 Hz, CF), 137.6 (dm,

¹J_C,F= 244.8 Hz, CF), 137.1 (dm, ¹J_C,F= 242.3 Hz, CF), 126.4 (m,

C_ipso), 44.4 [s, C(CH₃)₃], 42.0 [s, C(CH₃)₃], 38.5 (s, CH₂), 27.4 (s,

CH₃), 26.1 (s, CH₃) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ

ppm. ¹³C{¹H} NMR (75.5 MHz, C₆D₆, 25 °C): δ = 191.3 [s, CO

1

= –152.5 (m, 2 F, ortho-CF), –164.3 (m, 2 F, meta-CF), –164.9 (m, or CN(C₆F₅)], 177.2 [s, CO or CN(C₆F₅)], 141.7 (dm, J_C,F

=

1 F, para-CF) ppm. ¹⁹F NMR (282.4 MHz, THF/C₆D₆capillary,

25 °C): δ = –153.3 (m, 2 F, ortho-CF), –165.9 (m, 2 F, meta-CF),

–166.9 (m, 1 F, para-CF) ppm.

242.6 Hz, CF), 138.0 (dm, J_C,F= 250.5 Hz, CF), 137.7 (dm, ¹J_C,F

1

= 251.5 Hz, CF), 128.3 (m, C_ipso), 93.0 [d, J_Rh,C= 1.9 Hz, (tBu)(O)-

CCHC(tBu)N(C₆F₅)], 82.0 (d, J_Rh,C= 12.9 Hz, cod-CH), 77.1 (d,

J_Rh,C= 14.3 Hz, cod-CH), 42.6 [s, C(CH₃)₃], 40.8 [s, C(CH₃)₃], 31.9

(s, cod-CH₂), 31.7 [s, C(CH₃)₃], 29.1 (s, cod-CH₂), 29.0 [s, C-

(CH₃)₃] ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ = –144.6 (m,

[K{(tBu)(O)CCHC(tBu)N(C₆F₅)}] (19): (tBu)(O)CCH₂C(tBu)N-

(C₆F₅) (18) (30 mg, 0.113 mmol) was dissolved in THF (1 mL) and

treated with KH (8 mg, 0.190 mmol) at –20 °C. Gas evolution was

observed, and the colorless solution turned yellow. The reaction

mixture was stirred at room temperature for 30 min and analyzed

by NMR spectroscopy. The NMR spectra indicate a quantitative

reaction to yield 19. ¹H NMR (300.1 MHz, THF/C₆D₆capillary,

25 °C): δ = 5.46 (s, 1 H, CH), 1.54 [s, 9 H, C(CH₃)₃], 1.22 [s, 9 H,

C(CH₃)₃] ppm. ¹⁹F NMR (282.4 MHz, THF/C₆D₆capillary,

25 °C): δ = –157.1 (m, 2 F), –171.5 (m, 2 F), –180.7 (m, 1 F) ppm.

3

2 F, ortho-CF), –161.3 (t, J_F,F= 22.4 Hz, 1 F, para-CF), –164.0

(m, 2 F, meta-CF) ppm.

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(cod)] (2): (C₆F₅)-

NC(Me)CHC(Me)NH(C₆F₅) (17) (225 mg, 0.52 mmol) and KH

(29.4 mg, 0.73 mmol) were treated with THF (7 mL) at –40 °C. The

reaction mixture was allowed to reach room temperature and was

stirred for 2.5 h. The solution was transferred at –70 °C through

a PTFE cannula to a suspension of [{Rh(μ-Cl)(cod)}₂] (120 mg,

0.24 mmol) in THF (8 mL). The solution was allowed to reach

room temperature and was stirred overnight. The volatile com-

pounds were then removed under vacuum. The residue was ex-

tracted three times each with toluene (6 mL). The solvent was re-

moved under vacuum from the combined extracts. The resulting

solid was washed three times each with hexane (4 mL) at –40 °C.

The residue was dried under vacuum to yield [Rh{κ²(N,N)-(C₆F₅)-

NC(Me)CHC(Me)N(C₆F₅)}(cod)] (2) as a beige solid. Yield:

139.8 mg (0.22 mmol, 91%). C₂₅H₁₉F₁₀N₂Rh (640.32): calcd. C

46.89, H 2.99, N 4.37; found C 47.20, H 2.77, N 3.99. ¹H NMR

(300.1 MHz, C₆D₆, 25 °C): δ = 4.98 (s, 1 H, CH), 3.31 (br. s, 4 H,

cod-CH), 1.96 (m, 4 H, cod-CHH), 1.38 (s, 6 H, CH₃), 1.32 (m, 4

H, cod-CHH) ppm. ¹³C{¹H} NMR (75.5 MHz, C₆D₆, 25 °C): δ =

[K{(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}] (20): (C₆F₅)NC(Me)CHC-

(Me)NH(C₆F₅) (17) (271 mg, 0.6 mmol) was dissolved in THF

(8 mL). A suspension of KH (32 mg, 0.8 mmol) in THF (5 mL)

was added dropwise at –30 °C through a polytetrafluoroethylene

(PTFE) cannula. The solution was stirred, and gas evolution was

observed. Within 2 h, the solution was allowed to reach room tem-

perature. The clear yellow solution was analyzed by NMR spec-

troscopy. The NMR spectra indicate the formation of 20 in high

yield. ¹H NMR (300.1 MHz, THF/C₆D₆capillary, 25 °C): δ = 4.86

(s, 1 H, CH), 1.74 (s, 6 H, CH₃) ppm. ¹⁹F NMR (282.4 MHz, THF/

C₆D₆capillary, 25 °C): δ = –156.0 (m, 4 F, ortho-CF), –168.3 (m, 4

F, meta-CF), –174.3 (m, 2 F, para-CF) ppm.

[Rh{κ²-(N,O)-(tBu)(O)CCHC(tBu)N(C₆F₅)}(cod)] (1). (a) A solu-

tion of (tBu)(O)CCH₂C(tBu)N(C₆F₅) (18) (132 mg, 0.4 mmol) in

THF (5 mL) was added dropwise at –40 °C through a PTFE can-

nula to a suspension of KH (24 mg, 0.6 mmol) in THF (5 mL). The

reaction mixture was stirred at –40 °C for 15 min as well as at room

temperature for 15 min. The yellow solution was then added drop-

1

163.2 [s, CN(C₆F₅)], 142.0 (dm, J_C,F= 243.0 Hz, CF), 138.0 (dm,

1

¹J_C,F= 254.2 Hz, CF), 138.6 (dm, J_C,F= 249.2 Hz, CF), 126.8

(m, C_ipso), 100.8 [d, J_Rh,C= 1.5 Hz, C(Me)CHC(Me)], 79.1 (d, J =

12.7 Hz, cod-CH), 30.4 (s, codCH₂), 24.9 (s, CH₃) ppm. ¹⁹F NMR

(282.4 MHz, C₆D₆, 25 °C): δ = –147.8 (m, 4 F, ortho-CF), –159.0

3

(t, J_F,F= 22.4 Hz, 2 F, para-CF), –162.9 (m, 4 F, meta-CF) ppm.

wise at –40 °C to

a solution of [{Rh(μ-Cl)(cod)}₂] (97 mg,

0.2 mmol). The mixture was allowed to reach room temperature

slowly and afterwards stirred for 18 h. The color changed to red-

dish black. Volatile compounds were removed under vacuum. The

residue was extracted two times each with toluene (4 mL). After

removal of the solvent from the combined extracts under vacuum,

the resulting solid was extracted two times each with hexane

(6 mL). Concentration of the combined hexane phases under vac-

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(C₂H₄)₂] (3): THF

(8 mL) was added to (C₆F₅)NC(Me)CHC(Me)NH(C₆F₅) (17)

(165 mg, 0.39 mmol) and KH (22 mg, 0.54 mmol) at –65 °C. The

reaction mixture was stirred at –60 °C for 15 min and afterwards at

room temperature for 3 h. The pale yellow solution was transferred

dropwise through a PTFE cannula at –70 °C to a solution of

[{Rh(μ-Cl)(C₂H₄)₂}₂] (68 mg, 0.18 mmol) in THF (7.5 mL). The re-

uum yielded [Rh{κ²(N,O)-(tBu)(O)CCHC(tBu)N(C₆F₅)}(cod)] (1) action mixture was stirred at –60 °C for 30 min and at room tem-

as a pale yellow solid. Yield: 86 mg (0.2 mmol, 78%). (b) (tBu)(O)-

CCH₂C(tBu)N(C₆F₅) (18) (160 mg, 0.5 mmol) and lithium diiso-

perature for 18 h while the color turned dark red. The volatile com-

pounds were then removed under vacuum. The residue was ex-

Eur. J. Inorg. Chem. 2014, 2793–2808

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tracted with toluene (7 mL). After removal of the solvent from the

extract under vacuum, the solid was washed three times each with

pentane (3 mL) at –50 °C. The residue was dried under vacuum to

from the extract under vacuum. The pale brown solid was washed

at –30 °C three times each with hexane (4 mL). The beige solid was

dissolved in toluene (7 mL) and layered with hexane (2 mL). This

yield [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(C₂H₄)₂] (3) solution was stored at –30 °C. After 5 d, the solution was filtered

as a yellow solid. Yield: 152 mg (0.27 mmol, 74%). LIFDI TOF

MS: calcd. (%) for C₂₁H₁₅F₁₀N₂Rh⁺[M]⁺588.2; found 588.2 (100);

calcd. (%) for C₁₉H₁₁F₁₀N₂Rh⁺[M – (C₂H₄)]⁺560.2; found 560.2

at –30 °C. The residue was dried under vacuum to yield

[Rh{κ²(N,N)-(2,6-Me₂C₆H₃)NC(Me)CHC(Me)N(2,6-Me₂C₆H₃)}-

(CNtBu)₂] (5) as a beige microcrystalline solid. Yield: 180 mg

(0.3 mmol, 74%). C₃₁H₄₃N₄Rh (574.61): calcd. C 64.80, H 7.54, N

1

(65). H NMR (300.1 MHz, C₆D₆, 25 °C): δ = 4.96 (s, 1 H, CH),

2.45 (m, 4 H, CHH), 1.73 (m, 4 H, CHH), 1.36 (s, 6 H, CH₃) ppm. 9.75; found C 64.28, H 7.46, N 9.48. IR (ATR): ν = 2140 (vs,

˜

¹³C{¹H} NMR (75.5 MHz, C₆D₆, 25 °C): δ = 163.0 [s, CN(C₆F₅)],

CNtBu), 2103 (m, CNtBu), 2068 (s, CNtBu) cm^–1. ¹H NMR

1

3

142.1 (dm, J_C,F= 244.3 Hz, CF), 138.9 (dm, J_C,F= 241.1 Hz,

(300.1 MHz, C₆D₆, 25 °C): δ = 7.05 (br. d, J_H,H= 7.4 Hz, 4 H,

meta-ArH), 6.91 (br. t, J_H,H= 7.4 Hz, 2 H, para-ArH), 5.13 [s, 1

1

3

CF), 138.0 (dm, J_C,F= 251.0 Hz, CF), 125.7 (m, C_ipso), 100.7 [d,

J_Rh,C= 1.3 Hz, NC(Me)CHC(Me)N], 61.5 (d, J_Rh,C= 12.4 Hz,

H, NC(Me)CHC(Me)N], 2.56 (s, 12 H, ArCH₃), 1.62 (s, 6 H, CH₃),

CH₂), 25.0 (s, CH₃) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ

0.81 [s, 18 H, C(CH₃)₃] ppm. ¹³C{¹H} NMR (75.5 MHz, C₆D₆,

3

= –147.2 (m, 4 F, ortho-CF), –158.2 (t, J_F,F= 22.2 Hz, 2 F, para- 25 °C): δ = 158.1 (s, C=N or C_ipso), 157.3 (s, C=N or C_ipso), 150.5

1

CF), –162.9 (m, 4 F, meta-CF) ppm.

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CNtBu)₂] (4): At

[d, J_Rh,C= 63.0 Hz, RhCNC(CH₃)₃], 131.9 (s, C_ArCH₃), 127.8 (s,

meta-C_ArH), 123.4 (s, para-C_ArH), 97.5 [d, J_Rh,C= 2.4 Hz, NC(Me)

CHC(Me)N], 54.8 [s, CNC(CH₃)₃], 30.4 [s, CNC(CH₃)₃], 22.7 (s,

CH₃), 19.7 (s, C_ArCH₃) ppm.

–40 °C

(C₆F₅)NC(Me)CHC(Me)NH(C₆F₅)

(17)

(258 mg,

0.60 mmol) and KH (34 mg, 0.84 mmol) were treated with THF

(9 mL). The mixture was allowed to reach room temperature slowly

and stirred at room temperature for 4 h. The solution was transfer-

red at –70 °C through a PTFE cannula to a suspension of [{Rh(μ-

Cl)(coe)₂}₂] (226 mg, 0.30 mmol) in THF (8 mL). The solution was

allowed to reach room temperature and stirred overnight. A solu-

tion of CNtBu (100 mg, 137 μL, 1.20 mmol) in THF (5 mL) was

slowly added dropwise to the dark red reaction mixture. The solu-

tion was stirred at room temperature for 1 h. The volatile com-

pounds were then removed under vacuum. The residue was ex-

tracted with toluene (10 mL). After evaporation of the solvent, the

residue was extracted six times each with hexane (5 mL). The vol-

ume of the combined hexane phases was reduced under vacuum to

approximately 10 mL. The solution was stored at –30 °C, which led

to the precipitation of a pale yellow solid. After 48 h, the solid was

filtered off at –30 °C. The residue was dried under vacuum to yield

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)₂] (6a): (C₆F₅)-

NC(Me)CHC(Me)NH(C₆F₅) (17) (226.4 mg, 0.53 mmol) and KH

(26.4 mg, 0.66 mmol) were treated with THF (8 mL) at –30 °C. The

mixture was stirred at room temperature for 2 h. The yellow solu-

tion was added dropwise through a PTFE cannula to a yellow sus-

pension of [{Rh(μ-Cl)(CO)₂}₂] (93.0 mg, 0.24 mmol) in THF

(10 mL) at –70 °C. The solution was allowed to reach room tem-

perature and stirred at room temperature for 15 h. The color of the

solution turned to reddish black. The volatile compounds were

then removed under vacuum. The residue was extracted two times

each with toluene (10 mL), and afterwards the solvent was evapo-

rated from the combined extracts. The pale yellow solid was washed

at –90 °C five times each with pentane (5 mL). The residue was

dried under vacuum to yield [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC-

(Me)N(C₆F₅)}(CO)₂] (6a) as a beige solid. The solvent was removed

from the combined pentane fractions. The resulting residue was

dissolved in CH₂Cl₂and stored at –30 °C. After 3 d, the solution

was filtered at –30 °C by using a cannula. The residue was dried

under vacuum to yield 2,3,4,5,6-pentafluoro-N-[(Z)-6,7,8,9-tetra-

fluoro-2-methyl-1H-benzo[b]azepine-4(5H)-ylidene]benzeneamine

(22) as a colorless crystalline solid (see the Supporting Infor-

mation). Yield: 22: 22 mg (0.05 mmol, 10%); 6a: 121 mg

(0.21 mmol, 86%). Spectroscopic data for 6a: C₁₉H₇F₁₀N₂O₂Rh

(588.16): calcd. C 38.80, H 1.20, N 4.76; found C 39.26, H 1.16, N

4.96. Accurate ESI-MS⁺: calcd. for C₁₉H₈F₁₀N₂O₂Rh⁺[M + H]⁺:

588.9473; found 588.9476. Accurate ESI-MS^–: calcd. for

C₁₉H₆F₁₀N₂O₂Rh [MH]^–: 586.9327; found 586.9330; calcd. for

C₁₉H₇ClF₁₀N₂O₂Rh [M + Cl]^–: 622.9097; found 622.9097. GC–

MS: t_R= 23.0 min; m/z = 28, 103, 181, 208, 249, 296, 532 [M – 2

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CNtBu)₂]

as pale yellow powder. Yield: 172 mg (0.25 mmol, 82%).

C₂₇H₂₅F₁₀N₄Rh (698.40): calcd. C 46.43, H 3.61, N 8.02; found C

(4)

a

46.61, H 3.95, N 7.66. IR (ATR): ν = 2137 (m, CNtBu), 2094 (m,

˜

CNtBu), 2064 (m, CNtBu) cm^–1. ¹H NMR (300.1 MHz, C₆D₆,

25 °C): δ = 5.04 (s, 1 H, CH), 1.51 (s, 6 H, CH₃), 0.73 [s, 18 H,

C(CH₃)₃] ppm. ¹³C{¹H} NMR (75.5 MHz, C₆D₆, 25 °C): δ = 161.6

1

[s, CN(C₆F₅)], 147.8 [d, J_Rh,C= 65.1 Hz, RhCNC(CH₃)₃], 142.1

1

(dm, J_C,F= 244.9 Hz, CF), 139.3 (dm, J_C,F= 250.3 Hz, CF),

1

138.1 (dm, J_C,F= 250.3 Hz, CF), 133.8 (m, C_ipso), 100.3 [d, J_Rh,C

= 2.0 Hz, NC(Me)CHC(Me)N], 55.8 [s, CNC(CH₃)₃], 30.4 [s,

CNC(CH₃)₃], 23.2 (s, CH₃) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆,

3

25 °C): δ = –147.9 (m, 4 F, ortho-CF), –164.7 (t, J_F,F= 22.0 Hz, 2

F, para-CF), –165.5 (m, 4 F, meta-CF) ppm.

[Rh{κ²(N,N)-(2,6-Me₂C₆H₃)NC(Me)CHC(Me)N(2,6-Me₂C₆H₃)}-

CO]⁺, 560 [M – CO]⁺, 588 [M]⁺. IR (ATR): ν = 2070 (s, CO), 2020

˜

(CNtBu)₂] (5): (2,6-Me₂C₆H₃)NC(Me)CHC(Me)NH(2,6- (s, CO) cm^–1. H NMR (300.1 MHz, C₆D₆, 25 °C): δ = 4.90 (s, 1

1

Me₂C₆H₃) (21) (129 mg, 0.4 mmol) was dissolved in THF (9 mL). H, CH), 1.34 (s, 6 H, CH₃) ppm. H NMR (300.1 MHz, [D₈]THF,

At –40 °C nBuLi (1.6 molL^–1solution in hexane, 0.33 mL, 25 °C): δ = 5.55 (s, 1 H, CH), 1.94 (s, 6 H, CH₃) ppm. H NMR

1

0.5 mmol nBuLi) was added carefully. The mixture was stirred at

–30 °C for 3 h, and the colorless solution turned yellow. The reac-

tion solution was transferred slowly at –50 °C through a PTFE

cannula to a suspension of [{Rh(μ-Cl)(coe)₂}₂] (152 mg, 0.2 mmol)

in THF (9 mL). The solution was stirred for 3 h and allowed to

reach room temperature. The color of the solution changed from

ruby to a reddish black. A solution of CNtBu (70 mg, 97 μL,

0.8 mmol) in THF (7.5 mL) was then added dropwise at room tem-

perature. The solution was stirred at room temperature for 18 h.

The volatile compounds were removed under vacuum. The residue

was extracted with toluene (7 mL), and the solvent was removed

(300.1 MHz, 1,2-C₆H₄F₂/C₆D₆capillary, 25 °C): δ = 5.15 (s, 1 H,

CH), 1.68 (s, 6 H, CH₃) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C):

δ = –148.2 (m, 4 F, ortho-CF), –158.6 (t, ³J_F,F= 22.3 Hz, 2 F, para-

CF), –162.6 (m, 4 F, meta-CF) ppm. ¹⁹F NMR (282.4 MHz, [D₈]-

3

THF, 25 °C): δ = –149.4 (m, 4 F, ortho-CF), –161.3 (t, J_F,F

=

22.3 Hz, 2 F, para-CF), –164.6 (m, 4 F, meta-CF) ppm. ¹⁹F NMR

(282.4 MHz, 1,2-C₆H₄F₂/C₆D₆capillary, 25 °C): δ = –149.2 (m, 4

F, ortho-CF), –160.6 (t, J_F,F= 22.3 Hz, 2 F, para-CF), –164.2 (m,

3

4 F, meta-CF) ppm. Spectroscopic data for 22: C₁₇H₇F₉N₂(410.24):

calcd. C 49.77, H 1.72, N 6.83; found C 50.18, H 1.49, N 7.15.

GC–MS: t_R= 20.3 min; m/z = 28, 84, 216, 391 [M – F]⁺, 410

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1

[M]⁺. IR (ATR): ν = 3425 (w, NH), 1623 (w, CN) cm^–1. H NMR [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)(NCMe)]

˜

(300.1 MHz, C₆D₆, 25 °C): δ = 5.26 (br. s, 1 H, NH), 4.80 (s, 1 H, (7b): In a Schlenk tube, [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

CH), 3.59 (s, 2 H, CH₂), 1.06 (s, 3 H, CH₃) ppm. ¹⁹F NMR

(282.4 MHz, C₆D₆, 25 °C): δ = –144.48 (m, 1 F), –153.27 (m, 2 F),

–153.77 (m, 1 F), –157.54 (m, 1 F), –158.77 (m, 1 F), –161.57 (m,

1 F), –164.21 (m, 2 F) ppm.

N(C₆F₅)}(¹³CO)₂] (6b) (70 mg, 0.12 mmol) and ONMe₃(11 mg,

0.142 mmol) were treated with acetonitrile (20 mL). The reaction

mixture was stirred overnight. The gaseous as well as the liquid

phase were analyzed. In the gas phase, ¹³CO₂was identified with

the help of GC–MS. A resonance signal in the ¹³C{¹H} NMR spec-

trum of the reaction solution at δ = 124.8 ppm could be attributed

to ¹³CO₂(ref. C₆D₆capillary).^[32]The volatile compounds were re-

moved under vacuum, and the crude product was washed five times

each with hexane (7 mL) at room temperature. The residue was

dried under vacuum to yield [Rh{κ²(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(¹³CO)(NCMe)] (7b) as a yellow solid. Yield:

66 mg (0.11 mmol, 92 %). LIFDI TOF MS: calcd. (%) for

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)₂]

(6b):

(C₆F₅)NC(Me)CHC(Me)NH(C₆F₅) (17) (362 mg, 0.84 mmol) and

KH (41 mg, 1.03 mmol) were slowly treated with THF (10 mL) at

–30 °C. The mixture was allowed to reach room temperature and

stirred at room temperature for 5 h. The yellow solution was trans-

ferred at –70 °C with a PTFE cannula to a yellow suspension of

[{Rh(μ-Cl)(¹³CO)₂}₂] (147 mg, 0.37 mmol) in THF (10 mL). The

solution was stirred at room temperature for 15 h while the color

turned reddish brown. The volatile compounds were then removed

under vacuum. The residue was extracted two times each with tolu-

ene (10 mL), and the solvent was removed under vacuum from the

combined extracts. The pale yellow solid was washed at –70 °C five

times each with hexane (7 mL). Evaporation of the solvent yielded

[Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)₂] (6b) as a

beige solid. Yield: 408 mg (0.69 mmol, 93%). LIFDI TOF MS:

calcd. (%) for C₁₇¹³C₂H₇F₁₀N₂O₂Rh⁺[M]⁺590.2; found 590.2

C₁₉¹³CH₁₀F₁₀N₃ORh⁺[M]⁺602.2; found 602.2 (100). IR (ATR): ν

˜

= 2283 (vw, NCMe), 1946 (s, ¹³CO) cm^–1

.

¹³C{¹H} NMR

1

(75.5 MHz, C₆D₆, 25 °C): δ = 188.8 (d, J_Rh,C= 71.5 Hz, RhCO),

162.7 (s, C=N), 161.8 (s, C=N), 145–125 (m, C_Ar), 124.5 (s,

NCCH₃), 100.7 (d, J = 2.3 Hz, CH), 23.3 (s, CH₃), 22.9 (s, CH₃),

0.0 (s, NCCH₃) ppm.

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(PEt₃)] (8a):

A solution of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}-

(CO)(NCMe)] (7a) (22 mg, 0.04 mmol) in C₆D₆(0.7 mL) was

treated with PEt₃(5.5 mg, 6.9 μL, 0.05 mmol) at room temperature.

The orange-red solution was then examined by means of IR and

NMR spectroscopy. [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CO)(PEt₃)] (8a) was the sole rhodium species that could

(100). IR (ATR): ν = 2022 (s, ¹³CO), 1975 (s, ¹³CO) cm^–1. ¹³C{¹H}

NMR (75.5 MHz, C₆D₆, 25 °C): δ = 184.4 (d, J_Rh,C= 66.6 Hz,

C=O), 164.0 (s, C=N), 141.6 (dm, J_C,F= 246.2 Hz, CF), 139.6

(dm, J_C,F= 253.8 Hz, CF), 138.0 (dm, J_C,F= 254.9 Hz, CF),

132.6 (m, C_ipso), 101.3 (d, J_Rh,H= 2.3 Hz, CH), 22.6 (s, CH₃) ppm.

˜

1

[Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NMe₃)] (23):

be identified. IR (ATR, concentration of a C D solution of 8a): ν

˜

6

[Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)₂]

(6a)

= 1962 (s, CO) cm^–1. ¹H NMR (300.1 MHz, C₆D₆, 25 °C): δ = 4.76

(49 mg, 0.1 mmol) was dissolved in 1,2-difluorobenzene (2 mL) and

treated with ONMe₃(5.7 mg, 0.1 mmol). After 6 h, the gaseous

phase was analyzed. CO₂could be identified with the help of GC–

MS. The orange solution was examined by IR and NMR spec-

(s, 1 H, CH), 1.47 (s, 3 H, CH₃), 1.45 (s, 3 H, CH₃), 1.44–1.38 [br.

s, 6 H, P(CH₂CH₃)₃], 1.07–0.96 [br. s, 9 H, P(CH₂CH₃)₃] ppm. ¹⁹

F

NMR (282.4 MHz, C₆D₆, 25 °C): δ = –149.2 (m, 2 F, ortho-CF),

–155.0 (m, 2 F, ortho-CF), –165.2 (m, 2 F, meta-CF), –165.9 (m, 2

troscopy.

(NMe₃)] (23) was the only rhodium species that could be identified.

IR (ATR, concentration of a 1,2-C H F solution of 23): ν = 1954

[Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

3

F, meta-CF), –167.1 (t, J_F,F= 22.4 Hz, 1 F, para-CF), –168.9 (t,

³J_F,F= 22.6 Hz, 1 F, para-CF) ppm. ³¹P{¹H} NMR (121.5 MHz,

1

˜

C₆D₆, 70 °C): δ = 21.7 (d, J_Rh,P= 125.8 Hz) ppm.

6

4 2

(m, CO) cm^–1. H NMR (300.1 MHz, 1,2-C₆H₄F₂/C₆D₆capillary,

25 °C): δ = 5.05 (s, 1 H, CH), 2.79 [br. s, 9 H, N(CH₃)₃] 1.64 (s, 3

H, CH₃), 1.61 (s, 3 H, CH₃) ppm. ¹⁹F NMR (282.4 MHz, 1,2-

C₆H₄F₂/C₆D₆capillary, 25 °C): δ = –148.0 (m, 2 F, ortho-CF),

–150.0 (m, 2 F, ortho-CF), –164.2 (t, ³J_F,F= 20.5 Hz, 1 F, para-CF),

–164.8 (t, ³J_F,F= 21.4 Hz, 1 F, para-CF), –166.0 (m, 2 F, meta-CF),

–167.8 (m, 2 F, meta-CF) ppm.

1

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)-

(PEt₃)] (8b): A solution of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC-

(Me)N(C₆F₅)}(¹³CO)(NCMe)] (7b) (19 mg, 0.03 mmol) in C₆D₆

(0.6 mL) was treated with PEt₃(5.0 mg, 6.2 μL, 0.04 mmol) at

room temperature. The orange-red solution was then examined by

means of IR and NMR spectroscopy. [Rh{κ²(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(¹³CO)(PEt₃)] (8b) was the sole rhodium species

that could be identified. IR (ATR, concentration of a C₆D₆solu-

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

(7a): In a Schlenk tube [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CO)₂] (6a) (100 mg, 0.17 mmol) and ONMe₃(15 mg,

0.20 mmol) were treated with acetonitrile (20 mL) and stirred at

room temperature overnight. The gaseous phase was analyzed, and

CO₂could be identified with the help of GC–MS. The solvent was

removed under vacuum, and the crude product was washed five

times each with hexane (7 mL) at room temperature. The residue

was dried under vacuum to yield [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a) as a yellow solid. Yield:

99.7 mg (0.17 mmol, 98%). C₂₀H₁₀F₁₀N₃ORh (601.20): calcd. C

39.96, H 1.68, N 6.99; found C 39.91, H 1.96, N 6.48. Accurate

ESI-MS: calcd. for C₂₀H₁₁F₁₀N₃ORh⁺[M + H]⁺601.9792; found

tion of 8b): ν = 1914 (s, ¹³CO) cm^–1. ¹³C{¹H} NMR (75.5 MHz,

˜

C₆D₆, 25 °C): δ = 191.9 (dd, ¹J_Rh,C= 67.6, ²J_P,C= 17.5 Hz, RhCO),

169.3 (s, C=N), 166.2 (s, C=N), 145–125 (m, C_Ar), 105.6 (br. s, CH),

20.7 (s, CH₃), 19.8 (s, CH₃), 17.0 [t, ¹J_C,P= 12.8 Hz, P(CH₂CH₃)₃],

8.3 [s, P(CH₂CH₃)₃] ppm. ³¹P{¹H} NMR (121.5 MHz, C₆D₆,

1

2

70 °C): δ = 21.7 (dd, J_P,Rh= 125.8 Hz, J_P,C= 17.5 Hz) ppm.

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NH₃)] (9a):

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

(7a) (20 mg, 0.03 mmol) was dissolved in C₆D₆(0.6 mL). For

5 min, NH₃gas was bubbled through the reaction mixture with a

cannula. The orange-red solution was then examined by means of

601.9788. IR (ATR): ν = 2283 (vw, NCMe), 1992 (s, CO) cm^–1. ¹H IR and NMR spectroscopy. [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

˜

NMR (300.1 MHz, C₆D₆, 25 °C): δ = 5.03 (s, 1 H, CH), 1.51 (s, 3 CHC(Me)N(C₆F₅)}(CO)(NH₃)] (9a) was the sole rhodium species

H, CH₃), 1.44 (s, 3 H, CH₃), 0.03 (s, 3 H, NCCH₃) ppm. ¹⁹F NMR that could be identified. IR (ATR, concentration of a C₆D₆solu-

1

(282.4 MHz, C₆D₆, 25 °C): δ = –146.9 (m, 2 F, ortho-CF), –148.5

tion of 9a): ν = 1956 (m, CO) cm^–1. H NMR (300.1 MHz, C D ,

˜

6

(m, 2 F, ortho-CF), –160.8 (t, ³J_F,F= 22.1 Hz, 1 F, para-CF), –162.3 25 °C): δ = 5.02 (s, 1 H, CH), 1.44 (s, 3 H, CH₃), 1.42 (s, 3 H, CH₃),

(t, ³J_F,F= 22.2 Hz, 1 F, para-CF), –163.6 (m, 2 F, meta-CF), –165.3

(m, 2 F, meta-CF) ppm.

0.62 (s, 3 H, NH₃) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ

= –147.2 (m, 2 F, ortho-CF), –149.2 (m, 2 F, ortho-CF), –159.8 (t,

Eur. J. Inorg. Chem. 2014, 2793–2808

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³J_F,F= 22.3 Hz, 1 F, para-CF), –161.7 (t, ³J_F,F= 22.1 Hz, 1 F, para- RhH), 2017 (s, RhH) cm^–1. Spectroscopic data for [Rh{κ²-(N,N)-

CF), –162.6 (m, 2 F, meta-CF), –164.1 (m, 2 F, meta-CF) ppm.

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)(SiMe₃)(¹³CO)] (10b): ¹H

NMR (300.1 MHz, C₆D₆, 25 °C): δ = 5.06 (s, 1 H, CH), 1.49 (s, 3

H, CH₃), 1.44 (s, 3 H, CH₃), 0.31 [s, 9 H, Si(CH₃)₃], –12.34 (dd,

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)(NH₃)] (9b):

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(¹³CO)(NCMe)]

(7b) (21 mg, 0.03 mmol) was dissolved in C₆D₆(0.6 mL). For

5 min, NH₃gas was bubbled through the reaction mixture with a

cannula. The orange-red solution was then examined by means of

IR and NMR spectroscopy. [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC-

2

¹J_Rh,H= 22.2 Hz, J_C,H= 9.5 Hz, 1 H, RhH) ppm. ¹³C{¹H} NMR

1

(75.5 MHz, C₆D₆, 25 °C): δ = 188.2 (d, J_Rh,C= 67.1 Hz, RhCO)

ppm.

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

(Me)N(C₆F₅)}(¹³CO)(NH₃)] (9b) was the sole rhodium species that (NCMe)] (7a) with HSiEt₃: A solution of [Rh{κ²-(N,N)-(C₆F₅)-

could be identified. IR (ATR, concentration of a C₆D₆solution of

NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a) (15 mg,

9b): ν = 1910 (m, ¹³CO) cm^–1. ¹³C{¹H} NMR (75.5 MHz, C₆D₆, 0.025 mmol) in C₆D₆(0.6 mL) was treated with triethylsilane

˜

1

25 °C): δ = 190.5 (d, J_Rh,C= 74.6 Hz, RhCO), 162.7 (s, C=N),

161.1 (s, C=N), 150–130 (m, C_Ar), 100.6 (d, J_Rh,C= 2.5 Hz, CH),

23.7 (s, CH₃), 23.0 (s, CH₃) ppm.

(2.8 mg, 3.8 μL, 0.025 mmol) at room temperature. The orange-red

solution was then examined by means of IR and NMR spec-

troscopy. [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}-

(CO)(NCMe)] (7a), (C₆F₅)NC(Me)CHC(Me)NH(C₆F₅) (17), and

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)(SiEt₃)(CO)]

(11) could be identified. After a reaction time of 8 h, integration of

the ¹H and ¹⁹F NMR spectroscopic signals showed a 6:2:1 ratio of

7a/11/17. Spectroscopic data of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(H)(SiMe₃)(CO)] (11): IR (ATR, concentration

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

(NCMe)] (7a) with HSiMe₃: Trimethylsilane gas was bubbled

through a solution of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(CO)(NCMe)] (7a) (25 mg, 0.04 mmol) in C₆D₆(1 mL)

at room temperature for 5 min. The orange-red solution was then

examined by means of IR and NMR spectroscopy. After 5 h, the

resonance signals of 7a could no longer be detected. The volatile

compounds were cautiously removed under vacuum. The residue

was dissolved in C₆D₆(1 mL) and examined by means of IR and

NMR spectroscopy. [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(H)(SiMe₃)(CO)] (10a), [Rh{κ²-(N,N)-(C₆F₅)NC-

(Me)CHC(Me)N(C₆F₅)}(H)₂(SiMe₃)₂] (16), and (C₆F₅)NC(Me)-

CHC(Me)NH(C₆F₅) (17) could be identified. Integration of the ¹H

and ¹⁹F NMR spectroscopic signals showed a 12:1:1 ratio of 10a/

16/17. By increasing the reaction time to 8 h, the product ratio of

10a/16/17 changed to 5:2:3. IR (ATR, concentration of the solvent

of a C D reaction mixture): ν = 2025 (w, sh), 2018 (w), 2004 (vw)

˜

6

1

cm^–1. H NMR (300.1 MHz, C₆D₆, 25 °C): δ = 5.06 (s, 1 H, CH),

3

1.47 (s, 3 H, CH₃), 1.46 (s, 3 H, CH₃), 0.95 (t, J_H,H= 7.9 Hz, 9

H, CH₂CH₃), 0.53 (m, 6 H, CH₂CH₃), –12.30 (d, ¹J_Rh,H= 22.0 Hz,

1 H, RhH) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ = –145.8

3

(m, 2 F, ortho-CF), –150.1 (m, 2 F, ortho-CF), –160.1 (t, J_F,F

22.3 Hz, 1 F, para-CF), –160.6 (t, J_F,F= 22.1 Hz, 1 F, para-CF),

–162.9 (m, 2 F, meta-CF), –163.5 (m, 2 F, meta-CF) ppm.

=

3

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

(NCMe)] (7a) with HSiiPr₃: Triisopropylsilane (5.3 mg, 6.9 μL,

0.03 mmol) was added at room temperature to a solution of

from a reaction mixture in C D ): ν = 2072 (s, CO), 2025 (s, RhH),

˜

6

2017 (s, RhH) cm^–1. Spectroscopic data for [Rh{κ²-(N,N)-(C₆F₅)- [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

NC(Me)CHC(Me)N(C₆F₅)}(H)(SiMe₃)(CO)] (10a): ¹H NMR (7a) (20 mg, 0.03 mmol) in C₆D₆(0.7 mL). The orange-red solution

(300.1 MHz, C₆D₆, 25 °C): δ = 5.06 (s, 1 H, CH), 1.49 (s, 3 H, was examined by means of NMR spectroscopy. In addition to

1

CH₃), 1.44 (s, 3 H, CH₃), 0.31 [s, 9 H, Si(CH₃)₃], –12.34 (d, J_Rh,H[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

= 22.2 Hz, 1 H, RhH) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): (7a) and (C₆F₅)NC(Me)CHC(Me)NH(C₆F₅) (17), [Rh{κ²-(N,N)-

δ = –146.9 (m, 2 F, ortho-CF), –149.1 (m, 2 F, ortho-CF), –159.9 (C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)(SiiPr₃)(CO)] (12) could be

1

(m, 1 F, para-CF), –160.4 (m, 1 F, para-CF), –163.5 (m, 2 F, meta-

CF), –163.7 (m, 2 F, meta-CF) ppm. A signal in the ²⁹Si NMR

spectrum could not be detected. Spectroscopic data for {Rh[κ²-

(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)](H)₂(SiMe₃)₂} (16): ¹H

identified. After a reaction time of 2 d, integration of the H and

¹⁹F NMR spectroscopic signals showed a 20:2:1 ratio of 7a/12/17.

Spectroscopic data for [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)

N(C₆F₅)}(H)(SiiPr₃)(CO)] (12): ¹H NMR (300.1 MHz, C₆D₆,

NMR (300.1 MHz, C₆D₆, 25 °C): δ = 5.05 (s, 1 H, CH), 1.48 (s, 6 25 °C): δ = 5.08 (s, 1 H, CH), 1.58 (s, 3 H, CH₃), 1.47 (s, 3 H,

1

3

H, CH₃), 0.29 [s, 18 H, Si(CH₃)₃], –14.50 (d, J_Rh,H= 23.4 Hz, 2

CH₃), 0.99 [m, 3 H, CH(CH₃)₂], 0.88 [d, J_H,H= 7.4 Hz, 18 H,

H, RhH) ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ = –147.6 CH(CH₃)₂], –12.39 (d, J_Rh,H= 21.5 Hz, 1 H, RhH) ppm. ¹⁹F

1

(m, 4 F, ortho-CF), –161.6 (m, 2 F, para-CF), –163.4 (m, 4 F, meta-

NMR (282.4 MHz, C₆D₆, 25 °C): δ = –146.8 (m, 2 F, ortho-CF),

–147.9 (m, 2 F, ortho-CF), –160.2 (m, 1 F, para-CF), –160.6 (m, 1

F, para-CF), –163.1 (m, 2 F, meta-CF), –163.5 (m, 2 F, meta-CF)

ppm.

1

CF) ppm. H,²⁹Si HMBC NMR (300.1/59.6 MHz, C₆D₆, 25 °C): δ

1

= –14.50/35.5 [d, J_Rh,H= 23.4 Hz, Rh(H)(SiMe₃)].

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}-

(

¹³CO)(NCMe)] (7b) with HSiMe₃: Trimethylsilane gas was

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

(NCMe)] (7a) with HSiPh₃: In an NMR spectroscopy tube [Rh{κ²-

bubbled through a solution of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(¹³CO)(NCMe)] (7b) (25 mg, 0.04 mmol) in (N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a)

C₆D₆(1 mL) at room temperature for 5 min. The orange-red solu-

tion was then examined by means of IR and NMR spectroscopy.

After 5 h, the resonance signals of 7b could no longer be detected.

In the ¹³C{¹H} NMR spectrum, the resonance signal at δ =

181.5 ppm could be assigned to ¹³CO.^[33]The volatile compounds

were cautiously removed under vacuum. The residue was dissolved

in C₆D₆(1 mL) and examined by means of IR and NMR spec-

troscopy. [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)-

(10 mg, 0.02 mmol) and triphenylsilane (4.3 mg, 0.02 mmol) were

treated with C₆D₆(0.6 mL) at room temperature. The orange-red

solution was then examined by means of NMR spectroscopy. In

addition to [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N-

(C₆F₅)}(CO)(NCMe)] (7a) and (C₆F₅)NC(Me)CHC(Me)NH-

(C₆F₅) (17), [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N-

(C₆F₅)}(H)(SiPh₃)(CO)] (13) could be identified. After a reaction

1

time of 2 d, integration of the H and ¹⁹F NMR spectroscopic sig-

(SiMe₃)(¹³CO)] (10b) and [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)- nals showed a 7:1:1 ratio of 7a/13/17. Spectroscopic data for

N(C₆F₅)}(H)₂(SiMe₃)₂] (16) could be identified. IR (ATR, concen-

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H)(SiPh₃)(CO)]

tration of a C₆D₆reaction mixture): ν = 2022 (s, ¹³CO), 2025 (s, (13): ¹H NMR (300.1 MHz, C₆D₆, 25 °C): δ = 7.31 (m, 6 H, ArH),

˜

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7.06 (m, 9 H, ArH), 5.32 (s, 1 H, CH), 1.55 (s, 3 H, CH₃), 1.47 (s, at calculated positions and refined by using a riding model. CCDC-

3 H, CH₃), –11.58 (d, ¹J_Rh,H= 19.9 Hz, 1 H, RhH) ppm. ¹⁹F NMR 986662 (1), -986663 (2), -986664 (4), -986665 (5), -986666 (6a),

(282.4 MHz, C₆D₆, 25 °C): δ = –147.9 (m, 2 F, ortho-CF), –148.2

-986667 (7a), and -986668 (18) contain the supplementary crystal-

(m, 2 F, ortho-CF), –160.0 (m, 1 F, para-CF), –161.2 (m, 1 F, para- lographic data for this paper. These data can be obtained free of

CF), –163.5 (m, 2 F, meta-CF), –163.7 (m, 2 F, meta-CF) ppm.

charge from The Cambridge Crystallographic Data Centre via

www.ccdc.cam.ac.uk/data_request/cif.

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

(NCMe)] (7a) with HSi(OMe)₃: Trimethoxysilane (2.9 mg, 3.0 μL,

0.02 mmol) was added at room temperature to a solution of

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

(7a) (14 mg, 0.02 mmol) in C₆D₆(1 mL). The orange-red solution

was then examined by means of NMR spectroscopy. In addition to

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

(7a) and (C₆F₅)NC(Me)CHC(Me)NH(C₆F₅) (17), [Rh{κ²(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H){Si(OMe)₃}(CO)] (14) could

Compound 18: C₁₇H₂₀F₅NO, M_r= 349.34, crystal dimensions

0.40ϫ0.24ϫ0.16 mm; monoclinic; P2₁/c; a = 10.4069(8) Å, b =

14.9575(9) Å, c = 11.3092(10) Å, β = 104.553(6)°, Z = 4, V =

1703.9(2) Å³, ρ_calcd.= 1.362 gcm^–3; 2θ_max= 53.00; 3466 reflections

collected, 3466 were unique (R_int

= 0.0737), μ(Mo-K_α) =

0.122 mm^–1. Final R₁, wR₂, GoF values on all data: 0.1103, 0.0960,

1.027; R₁, wR₂, GoF values for reflections with I_oϾ2σ(I_o): 0.0595,

0.0850, 1.029; residual electron density: +0.19/–0.22 eÅ^–3.

1

be identified. After a reaction time of 18 h, integration of the H

Compound 1: C₂₅H₃₁F₅NORh, M_r= 559.42, crystal dimensions

0.24ϫ0.18ϫ0.12 mm; monoclinic; P2₁/c; a = 14.0849(6) Å, b =

14.3360(7) Å, c = 12.7259(6) Å, β = 112.899(3)°, Z = 4, V =

2367.12(19) Å³, ρ_calcd.= 1.570 gcm^–3; 2θ_max= 59.18°; 45634 reflec-

tions collected, 6388 were unique (R_int= 0.049), μ(Mo-K_α) =

0.78 mm^–1. Final R₁, wR₂, GoF values on all data: 0.0398, 0.0820,

1.112; R₁, wR₂, GoF values for reflections with I_oϾ2σ(I_o): 0.0342,

0.0845, 1.081; residual electron density: +1.32/–0.95 eÅ^–3.

and ¹⁹F NMR spectroscopic signals showed a 10:1:3 ratio of 7a/14/

17. Spectroscopic data for [Rh{κ²(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(H){Si(OMe)₃}(CO)] (14): ¹H NMR (300.1 MHz, C₆D₆,

25 °C): δ = 4.93 (s, 1 H, CH), 3.51 (s, 9 H, OCH₃), 1.56 (s, 3 H,

1

CH₃), 1.49 (s, 3 H, CH₃), –12.29 (d, J_Rh,H= 23.5 Hz, 1 H, RhH)

ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ = –146.5 (m, 2 F,

ortho-CF), –148.2 (m, 2 F, ortho-CF), –158.6 (m, 1 F, para-CF),

–159.6 (m, 1 F, para-CF), –162.6 (m, 2 F, meta-CF), –163.9 (m, 2

F, meta-CF) ppm.

Compound 2: C₂₅H₁₉F₁₀N₂Rh, M_r= 640.33, crystal dimensions

¯

0.20ϫ0.20ϫ0.05 mm; triclinic; P1;

a = 9.5142(4) Å, b =

Reaction of [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)-

(NCMe)] (7a) with HSi(OEt)₃: [Rh{κ²-(N,N)-(C₆F₅)NC(Me)-

CHC(Me)N(C₆F₅)}(CO)(NCMe)] (7a) (24 mg, 0.04 mmol) was dis-

solved in C₆D₆(1 mL). Triethoxysilane (6.6 mg, 7.4 μL, 0.04 mmol)

was added dropwise at room temperature. The orange-red solution

was then examined by means of NMR spectroscopy. In addition to

[Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(CO)(NCMe)]

(7a) and (C₆F₅)NC(Me)CHC(Me)NH(C₆F₅) (17), [Rh{κ²-(N,N)-

(C₆F₅)NC(Me)CHC(Me)N(C₆F₅)}(H){Si(OEt)₃}(CO)] (15) could

11.3735(5) Å, c = 11.8158(5) Å, α = 77.144(4)°, β = 87.940(3)°, γ =

69.599(4)°, Z = 2, V = 1166.82(9) Å³, ρ_calcd.= 1.823 gcm^–3; 2θ_max

= 50.02°; 11681 reflections collected, 4105 were unique (R_int

=

0.0579), μ(Mo-K_α) = 0.830 mm^–1. Final R₁, wR₂, GoF values on

all data: 0.0247, 0.0670, 1.039; R₁, wR₂, GoF values for I_oϾ2σ(I_o):

0.0269, 0.0618, 1.039; residual electron density: +0.57/–0.72 eÅ^–3.

Compound 4: C₂₇H₂₅F₁₀N₄Rh, M_r= 698.42, crystal dimensions

0.30ϫ0.15ϫ0.15 mm; monoclinic; P2₁/c; a = 15.5977(5) Å, b =

9.2673(4) Å, c = 19.8974(6) Å, β = 92.326(2)°, Z = 4, V =

2873.77(18) Å³, ρ_calcd.= 1.614 gcm^–3; 2θ_max= 58.00°; 50085 reflec-

tions collected, 7638 were unique (R_int= 0.0812), μ(Mo-K_α) =

0.683 mm^–1. Final R₁, wR₂, GoF values on all data: 0.0508, 0.0846,

1.051; R₁, wR₂, GoF values for reflections with I_oϾ2σ(I_o): 0.0387,

0.0800, 1.051; residual electron density: +0.62/–0.74 eÅ^–3.

1

be identified. After a reaction time of 18 h, integration of the H

and ¹⁹F NMR spectroscopic signals showed an 8:3:1 ratio of 7a/15/

17. Spectroscopic data for [Rh{κ²-(N,N)-(C₆F₅)NC(Me)CHC(Me)-

N(C₆F₅)}(H){Si(OEt)₃}(CO)] (15): ¹H NMR (300.1 MHz, C₆D₆,

3

25 °C): δ = 5.05 (s, 1 H, CH), 3.64 (q, J_H,H= 7.0 Hz, 6 H,

3

OCH₂CH₃), 1.55 (s, 3 H, CH₃), 1.49 (s, 3 H, CH₃), 1.06 (t, J_H,H

= 7.0 Hz, 9 H, OCH₂CH₃), –12.17 (d, ¹J_Rh,H= 23.4 Hz, 1 H, RhH)

ppm. ¹⁹F NMR (282.4 MHz, C₆D₆, 25 °C): δ = –148.4 (m, 2 F,

ortho-CF), –149.2 (m, 2 F, ortho-CF), –160.5 (m, 1 F, para-CF),

–160.9 (m, 1 F, para-CF), –163.2 (m, 2 F, meta-CF), –163.4 (m, 2

F, meta-CF) ppm.

Compound 5: C₃₁H₄₃N₄Rh, M_r= 574.60, crystal dimensions

0.40ϫ0.20ϫ0.14 mm; monoclinic; C2/c; a = 19.5039(6) Å, b =

16.2291(3) Å, c = 19.2485(6) Å, β = 105.313(2)°, Z = 8, V =

5876.4(3) Å³, ρ_calcd.= 1.299 gcm^–3; 2θ_max= 55°; 46122 reflections

collected, 6740 were unique (R_int

= 0.0717), μ(Mo-K_α) =

0.606 mm^–1. Final R₁, wR₂, GoF values on all data: 0.0390, 0.0532,

1.018; R₁, wR₂, GoF values for reflections with I_oϾ2σ(I_o): 0.0286,

0.0509, 1.018; residual electron density: +0.43/–0.53 eÅ^–3.

Density Functional Calculations: All calculations were performed

by using the Gaussian 09 (Revision C01)^[45]program package with

the B3LYP functional. The carbon, fluorine, and hydrogen atoms

(except the metal-bound hydrogen atoms) were described by using

the cc-pVDZ basis set. For nitrogen, silicon, and the metal-bound

hydrogen atoms, the cc-pVTZ basis set was applied. In the case of

4, all atoms except rhodium were described by using the cc-pVDZ

basis set. Rhodium was described by using relativistic effective core

potentials (RECPs) with the associated cc-pVDZ-PP basis set.^[46]

The nature of the minimum structures was verified by the absence

of imaginary frequencies by frequency mode analyses.

Compound 6a: C₁₉H₇F₁₀N₂O₂Rh, M_r= 588.18, crystal dimensions

0.28ϫ0.20ϫ0.08 mm; monoclinic; P2₁/n; a = 13.2668(5) Å, b =

7.5056(2) Å, c = 20.1044(6) Å, β = 98.908(3)°, Z = 4, V =

1977.75(11) Å³, ρ_calcd.= 1.975 gcm^–3; 2θ_max= 58.36°; 20687 reflec-

tions collected, 5327 were unique (R_int= 0.0286), μ(Mo-K_α) =

0.977 mm^–1. Final R₁, wR₂, GoF values on all data: 0.0374, 0.0858,

1.054; R₁, wR₂, GoF values for reflections with I_oϾ2σ(I_o): 0.0333,

0.0836, 1.054; residual electron density: +1.07/–1.08 eÅ^–3.

Structural Determination: Diffraction data of 18, 1, 2, 4, 5, 6a, and

7a were collected with a STOE IPDS 2θ diffractometer with Mo-

K_αradiation (λ = 0.71073 Å) at 100 K. Crystallographic data are

given below. The structures were solved by direct methods

(SHELXS-97)^[47](except for compound 7a, which was solved by

SIR-97^[48]) and refined with full-matrix least-square methods on F²

(SHELX-97, SHELXL-2013).^[47]The hydrogen atoms were placed

Compound 7a: C₂₀H₁₀F₁₀N₃ORh, M_r= 601.22, crystal dimensions

¯

0.24ϫ0.15ϫ0.04 mm; triclinic; P1;

a = 7.3288(5) Å, b =

11.7219(8) Å, c = 12.8497(8) Å, α = 91.815(5)°, β = 106.069(5)°, γ

= 102.360(6)°, Z = 2, V = 1031.30(12) Å³, ρ_calcd.= 1.936 gcm^–3;

2θ_max= 56.42°; 11047 reflections collected, 4955 were unique (R_int

= 0.0587), μ(Mo-K_α) = 0.937 mm^–1. Final R₁, wR₂, GoF values on

all data: 0.0580, 0.0748, 0.989; R₁, wR₂, GoF values for reflections

Eur. J. Inorg. Chem. 2014, 2793–2808

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FULL PAPER

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Supporting Information (see footnote on the first page of this arti-

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calculations as well as Cartesian coordinates for all optimized

structures.

Acknowledgments

We would like to acknowledge the Deutsche Forschungsgemein-

schaft (DFG) for financial support. The Cluster of Excellence

“Unifying Concepts in Catalysis” (UniCat) funded by the DFG

is gratefully acknowledged. We are grateful to Annemarie Bittner,

Johannes Kohlmann, and Hanna Baumgarth for experimental as-

sistance.

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Received: February 20, 2014

Published Online: May 16, 2014

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2808

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Synthesis and structures of fluorinated (β-diketiminato)rhodium complexes: Si-H activation of silanes at a carbonyl complex

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