Configurational flexibility of epimeric β-aminothioether-chelated ruthenium(II) η6-arene complex salts

Conﬁgurational Flexibility of Epimeric β-Aminothioether-chelated

Ruthenium(II) η⁶-Arene Complex Salts

Immo Weber^a,c, Frank W. Heinemann^a, Walter Bauer^b, and Ulrich Zenneck^a

^aDepartment Chemie & Pharmazie, Anorganische Chemie, Egerlandstraße 1,

Friedrich-Alexander-Universita¨t Erlangen-Nu¨rnberg, D-91058 Erlangen, Germany

^bDepartment Chemie & Pharmazie, Organische Chemie, Henkestraße 42,

Friedrich-Alexander-Universita¨t Erlangen-Nu¨rnberg, D-91054 Erlangen, Germany

^cPresent address: Institut fu¨r Physikalische Chemie, Technische Universita¨t Bergakademie Freiberg,

Leipziger Straße 29, D-09596 Freiberg, Germany

Reprint requests to Prof. Dr. Ulrich Zenneck. Fax: ++49/(0) 9131 8527367.

E-mail: ulrich.zenneck@chemie.uni-erlangen.de

Z. Naturforsch. 2009, 64b, 123 – 140; received November 16, 2008

Dedicated to Professor Otto J. Scherer on the occasion of his 75^thbirthday

Five chiral β-aminothioethers were obtained via different routes orientated on literature proto-

cols. Three of these β-aminothioethers were reacted with two di-µ-chloro-bis{chloro[η⁶-arene]-

ruthenium(II)} derivatives, resulting in the title complex salts. The complex cations exhibit three

stereocenters, viz. ruthenium and sulfur atoms and the chiral benzylic carbon atom of the chelate lig-

and backbone. Both, ruthenium and sulfur stereocenters epimerize into a mixture of four NMR distin-

guishable diastereomers in equilibrium, but the designed chiral benzylic carbon atom is stable under

all conditions applied so far. The relative diastereomer concentrations in solution depend mainly on

the spatial requirements of the η⁶-arene ligand rather than on the thioether moiety. Diastereomer

ratios and the absolute conﬁgurations in solution were studied by NMR and CD spectroscopy. The

spectroscopic results ﬁt to the absolute X-ray crystal structure parameters determined for the diastere-

omers present in the crystalline state.

Key words: Ruthenium, Arene Complexes, β-Aminothioether Ligands, Stereochemistry, CD Spec-

troscopy, Epimerization Equilibrium

Introduction

come if the thioether bears at least one additional

donor functionality to form a chelate. Hamaker and

Thioether and thiolato Ru(II) η⁶-arene complexes co-workers introduced Schiff base ligands with N- and

and the selenium or tellurium analogs thereof are S-donor functionalities to obtain salts with the cations

rare [1], but have experienced an increasing interest [RuCl(η⁶-arene)(N∩S)]⁺which are stable in air and

recently. Mashima prepared bis-thiolato, thiolato and with respect to hydrolysis [1h]. Bennett and Goh

µ-bridged thiolate, selenolate and tellurolate Ru(II) placed a Ru(II) η⁶-HMB (= hexamethylbenzene) frag-

η⁶-arene complexes, which exhibit pπ backbonding ment into a trithio crown ether, which was opened un-

from the chalcogenido moiety to the Ru(II) center and der base-induced fragmentation to a bis-thiolato Ru(II)

a tendency for dimerization unprecedented for Ru(II) η⁶-HMB complex in the ﬁrst step and underwent also

η⁶-arene complexes [1a, b]. Che´rioux, Su¨ss-Fink, and base-induced intramolecular Michael cyclization to an

Therrien extended this class of complexes to dinu- ansa-thioether Ru(II) η⁶-arene complex [1i – l]. A re-

clear hydrido clusters [1c – f] which can act as reduc- lated observation was made by Teixidor and Hurst-

tive desulfuration reagents. While such chalcogenido house for thioether η⁶-arene Ru(II) carborane com-

complexes are air-sensitive due to enhanced electron plexes [1m], and some complexes of this class react

density at the Ru(II) center, monodentate thioethers also with alkynes [1n]. Successful applications of chi-

complexed to Ru(II) η⁶-arene fragments are air-stable, ral thioether complexes in enantioselective catalysis

but coordinatively labile; nevertheless Ru(II) η⁶-arene are rare [2a – g]. An inherent problem is the control of

complexes bearing monodentate thioether ligands can the conﬁgurational stability of the coordinated sulfur

be isolated [1g]. This coordinative lability can be over- atom. Inversion barriers of ∆G^‡= 41 – 49 kJ mol⁻¹

298

c

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

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Table 1. Selected bond lengths (A) and angles (deg) of the

hydrogen p-tosylate salt 9.

Distances

N(1)–C(7)

S(1)–C(8)

S(1)–C(9)

C(7)–C(8)

C(6)–C(7)

S(2)–O(1)

S(2)–O(2)

S(2)–O(3)

S(2)–C(19)

Angles

1.502(3)

1.806(2)

1.776(3)

1.525(3)

1.516(3)

1.441(2)

1.459(2)

1.461(2)

1.779(2)

N(1)–C(7)–C(8)

N(1)–C(7)–C(6)

C(7)–C(8)–S(1)

C(6)–C(7)–C(8)

C(8)–S(1)–C(9)

O(1)–S(2)–O(2)

O(1)–S(2)–O(3)

O(2)–S(2)–O(3)

O(3)–S(2)–C(19)

108.4(2)

120.8(2)

112.0(2)

113.0(2)

102.8(2)

113.4(2)

133.3(2)

110.5(2)

106.1(1)

˚

Table 2. Interionic hydrogen bonds (A, deg) in the hydrogen

p-tosylate salt 9.

D – H···A

d(D–H) d(H···A) d(D···A) ∠ (D–H···A)

N(1)–H(1A)...O(3)

N(1)–H(1B)...O(2)^a

N(1)–H(1B)...O(1)^b

N(1)–H(1C)...O(3)^c

N(1)–H(1C)...O(2)^c

0.91

1.87

2.01

2.36

2.29

2.36

2.769(3)

2.834(3)

2.930(3)

3.180(3)

3.008(3)

171.4

149.3

120.2

167.0

127.7

Scheme 1. Preparation of chiral β-aminothioethers 4 – 7;

Symmetry transformations: ^a−x+1, y−1, −z+1; ^b−x+1, y, −z+

a) see ref. [6b]; b) MeSO₂Cl (1.23 equiv.), Et₃N (1.51

1; ^cx, y−1, z.

◦

equiv.), CH₂Cl₂, 0 C to r. t.; c) 1 – 2.2 equiv. RSK; THF,

MeOH as indicated in the Exp. Section; work-up with 36 %

HCl; d) up to 20 % formation of 8 in a side reaction of path

c; e) (p-Tol)SO₃H·(H₂O) (1.01 equiv.), EtOH, recrystalliza-

tion; f) see ref. [7a – b]; g) Ishibashi protocol for 4, 5 and 7

(1.3 – 2.9 equiv. RSH / 2.2 – 4.9 equiv. RSNa / 12 – 24 h re-

ﬂux in n-PrOH); h) 1. Na (4.88 equiv.), ^tBuOH (1.26 equiv.),

liquid NH₃, THF, −78 ^◦C; 2. excess NH₄Cl; 3. EtOH, 36 %

HCl; i) 1. KSAc (1.49 equiv.), MeOH, THF; 2. excess gas.

NH₃, all r. t.; j) 1. ^tBuOK (1.81 equiv.), MeOH; 2. PrenylBr

(1.12 equiv.); 3. 36 % HCl, all r. t.; k) 1. ^tBuOK (1.10 equiv.),

THF; 2. PrenylBr (1.19 equiv.); 3. 36 % HCl, all r. t.

for Pt(IV) [2h] and of ∆G^‡

= 51– 56 kJ mol⁻¹for

Fig. 1. Diplacement ellipsoid plot (50 % probability) of the

molecular structure of hydrogen p-tosylate salt 9. For se-

lected intraionic distances and angles see Table 1; interionic

hydrogen bonds are listed in Table 2.

298

Cr(0)(CO)₅thioether complexes were found [2i]. Low

inversion barriers of the coordinated sulfur atoms were

also observed for simple pyridyl- and pyrimidyl-thio-

ether Ru(II) complexes [2j].

Results and Discussion

The factors controlling the inversion barriers of

Ru(II)-coordinated thioethers is addressed in the work

presented here by complexing various chiral β-amino

Syntheses of the chiral β-amino thioether ligands

β-Amino sulﬁdes are versatile intermediates in or-

thioether ligands on two Ru(II) η⁶-arene fragments. ganic synthesis [5a – i]. They are important as build-

The intention was to address the question whether it ing blocks of biologically active compounds [5j – n].

is possible to transfer the concept of Noyori [3a – i] (R)-Phenyl-glycinol (1) [6a] was converted into the

for enantioselective ruthenium transfer hydrogenation mesylate 3 in high yield and sufﬁcient purity for

catalysts from chiral β-aminoalcohol chelate ligands further reactions without work-up [2h, 6b] via the

to their β-aminothioether analogs. Although conﬁg- BOC protected (R)-β-amino alcohol 2 (Scheme 1).

urational stability is not always a requirement for a 3 was reacted then with 1.0– 2.2 equiv. of vari-

highly enantioselective transfer hydrogenation catalyst ous thiolates at ambient temperature, and the re-

as shown by Pfeffer [3j], the understanding of con- sulting BOC derivatives were deprotected in situ

ﬁgurational stability of chiral Ru(II) centers contain- with aqueous HCl to form the β-aminothioethers

ing η⁶-arene ligands is a major goal of our ongoing 4 – 7. The formation of 5 and 7 was accompanied

work [4].

by the formation of up to 20 % (4R)-4-phenyl-2-

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Arene:

R^ꢀ:

p-cymene

Ph

16

67 %

mesitylene

Ph

17

80 %

mesitylene

β-Naph

18

mesitylene

Prn

19

78 %

Scheme 2. Preparation of (β-aminothio-

ether)(η⁶-arene)Ru(II) complex cations

16 – 19; a) 1. 5, 7, 13 (> 2 equiv.), MeOH,

r. t.; 2. excess NaPF₆.

Yield

83 %

oxazolidinone 8 as a by-product, which was difﬁcult hydrochloride salt, because the free base 11 is con-

to remove.

Raw product 4 was sufﬁciently pure again for the

next step, and crude 6 contained only traces of 8. Proto-

nation of β-aminothioether 6 by p-tosic acid led to am-

monium p-tosylate salt 9 whose (R) conﬁguration was

conﬁrmed by X-ray crystal structure analysis (Fig. 1,

Table 1).

siderably sensitive towards oxidation to form the cor-

responding disulﬁde. The analogous in situ reaction

of 3 with potassium thioacetate [7e – g] followed by

aminolysis of the acetyl group gave the BOC-protected

β-amino thiol 12 only in 40 % yield. The nucleophilic

substitution reaction with thioacetate proceeded with

good selectivity (TLC), but 8 was observed again

in considerable amounts during the aminolysis step.

Attempted BOC deprotection of 12 to yield 10 re-

sulted only in quantitative formation of 8 instead, al-

though analogous BOC-deprotection is reported for

(R)-valinthiol [2g]. In situ deprotonation of 10 or 12

with t-BuOK followed by allylation lead to clean for-

mation of the desired β-amino prenylthioether 13 in

high yields with only trace impurities. Attempted chro-

matographic puriﬁcation of 13 reduced the yield sig-

niﬁcantly. The product is thermosensitive and cannot

be distilled.

The ethyl group of the β-ammonium thioether

cation of 9 adopts an antiperiplanar conformation in

the solid state. Slightly shortened C(7)–C(8) and elon-

gated C(7)–N(1) bonds might indicate a weak σ-σ*

effect [6a – d], but crystal packing and/or hydrogen

bonding between the p-tosylate and the ammonium

group may also affect the details of the molecular

structure of 9 in the solid state (Table 2). To circum-

vent the detrimental by-product formation, this dis-

advantage was taken as an opportunity to use 8 it-

self as an aziridine equivalent for the preparation of

β-aminothioethers. For that purpose, 1 was converted

to 8 [7a – b], and then the Ishibashi protocol [7c – d]

was applied for the syntheses of 4, 5 and 7. This reac-

tion requires an excess of thiol and thiolate. The yields

of the Ishibashi reaction are only high for 4 and 5, be-

cause a moderately volatile thiol is optimal in that case.

Vapor pressure of the thiol is not the only issue for a

successful application of this reaction sequence as we

learned from an unsuccessful attempt to prepare an iso-

propyl thioether in this way.

Syntheses and crystallographic study of the diaste-

reomeric β-aminothioether-chelated Ru(II) η⁶-arene

complex salts

Ligands 5 – 7 reacted smoothly with the Ru(II) η⁶-

cymene and η⁶-mesitylene complex dimers 14 [8a, b]

and 15 [8a] in all combinations with excess NaPF₆

in MeOH to yield σ(N) : σ(S) β-aminothioether η⁶-

arene Ru(II) chelate complex PF₆salts. However, only

the combinations 14 – 5, 15 – 5, and 15 – 7 gave crys-

With the aim of getting access to β-amino prenyl- talline salts with the cations 16 – 18 (Scheme 2) which

thioether 13, intermediate 10 was obtained by deben- could be characterized by X-ray crystal structure anal-

zylation of 4 following Mellor’s protocol [7e] with the ysis (Figs. 2 – 4). Only as η⁶-ligand anti (a) and R^ꢀsyn

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Table 3. Selected bond lengths (A) and angles (deg) of the Table 6. Selected bond lengths (A) and angles (deg) of com-

complex cation 16 (only the diastereomer 16as present in the plex cation 18as.

crystal of [16][PF₆] examined).

Distances

Angles

Distances

Angles

Ru(2)–Cl(2)

Ru(2)–S(2)

Ru(2)–N(2)

Ru(2)–C(31)

Ru(2)–C(32)

Ru(2)–C(33)

Ru(2)–C(34)

Ru(2)–C(35)

Ru(2)–C(36)

N(2)–C(41)

S(2)–C(42)

C(41)–C(42)

C(41)–C(43)

S(2)–C(49)

2.398(2)

2.386(2)

2.145(5)

2.180(6)

2.198(7)

2.206(6)

2.188(6)

2.231(6)

1.507(6)

1.819(5)

1.521(6)

1.514(7)

1.798(6)

Cl(2)–Ru(2)–S(2)

Cl(2)–Ru(2)–N(2)

S(2)–Ru(2)–N(2)

S(2)–Ru(2)–C(35)

S(2)–Ru(2)–C(36)

N(2)–Ru(2)–C(33)

N(2)–Ru(2)–C(34)

Cl(2)–Ru(2)–C(31)

Cl(2)–Ru(2)–C(32)

C(49)–S(2)–C(42)

S(2)–C(42)–C(41)

C(42)–C(41)–N(2)

C(42)–C(41)–C(43)

Ru(2)–S(2)–C(42)

Ru(2)–N(2)–C(41)

88.97(6)

81.0(2)

81.5(2)

Ru(1)–Cl(1)

Ru(1)–S(1)

Ru(1)–N(1)

Ru(1)–C(1)

Ru(1)–C(2)

Ru(1)–C(3)

Ru(1)–C(4)

Ru(1)–C(5)

Ru(1)–C(6)

N(1)–C(11)

S(1)–C(12)

C(11)–C(12)

C(11)–C(13)

S(1)–C(19)

2.392(2)

2.369(2)

2.129(4)

2.200(4)

2.193(4)

2.229(4)

2.197(5)

2.189(4)

2.239(5)

1.511(5)

1.827(4)

1.522(6)

1.513(6)

1.799(4)

Cl(1)–Ru(1)–S(1)

Cl(1)–Ru(1)–N(1)

S(1)–Ru(1)–N(1)

S(1)–Ru(1)–C(6)

S(1)–Ru(1)–C(1)

N(1)–Ru(1)–C(4)

N(1)–Ru(1)–C(5)

Cl(1)–Ru(1)–C(3)

Cl(1)–Ru(1)–C(2)

C(19)–S(1)–C(12)

S(1)–C(12)–C(11)

C(12)–C(11)–N(1)

C(12)–C(11)–C(13)

Ru(1)–S(1)–C(12)

Ru(1)–N(1)–C(11)

90.40(4)

82.4(1)

82.2(1)

165.7(2)

146.6(2)

164.7(2)

148.6(2)

159.8(2)

151.1(2)

100.4(3)

108.8(3)

109.1(4)

109.2(4)

98.3(2)

159.0(2)

153.2(2)

157.3(2)

156.2(2)

157.8(2)

153.4(2)

117.1(2)

106.0(3)

108.2(3)

112.9(3)

99.5(2)

118.7(3)

115.3(3)

˚

Table 7. Selected bond lengths (A) and angles (deg) of com-

plex cation 18sa.

Distances

˚

Table 4. Selected bond lengths (A) and angles (deg) of com-

plex cation 17as.

Angles

Ru(1)–Cl(1)

Ru(1)–S(1)

Ru(1)–N(1)

Ru(1)–C(1)

Ru(1)–C(2)

Ru(1)–C(3)

Ru(1)–C(4)

Ru(1)–C(5)

Ru(1)–C(6)

N(1)–C(11)

S(1)–C(12)

C(11)–C(12)

C(11)–C(13)

S(1)–C(19)

2.398(2)

2.382(2)

2.181(5)

2.209(6)

2.234(6)

2.225(7)

2.230(7)

2.210(6)

2.232(6)

1.478(6)

1.829(5)

1.516(6)

1.528(7)

1.808(6)

Cl(1)–Ru(1)–S(1)

Cl(1)–Ru(1)–N(1)

S(1)–Ru(1)–N(1)

S(1)–Ru(1)–C(1)

S(1)–Ru(1)–C(6)

N(1)–Ru(1)–C(2)

N(1)–Ru(1)–C(3)

Cl(1)–Ru(1)–C(4)

Cl(1)–Ru(1)–C(5)

C(19)–S(1)–C(12)

S(1)–C(12)–C(11)

C(12)–C(11)–N(1)

C(12)–C(11)–C(13)

Ru(1)–S(1)–C(12)

Ru(1)–N(1)–C(11)

93.64(6)

81.1(2)

81.2(2)

Distances

Angles

Ru(2)–Cl(2)

Ru(2)–S(2)

Ru(2)–N(2)

Ru(2)–C(25)

Ru(2)–C(26)

Ru(2)–C(27)

Ru(2)–C(28)

Ru(2)–C(29)

Ru(2)–C(30)

N(2)–C(35)

S(2)–C(36)

C(35)–C(36)

C(35)–C(37)

S(2)–C(43)

2.407(1)

2.373(1)

2.144(3)

2.193(4)

2.225(4)

2.226(4)

2.198(4)

2.202(4)

2.223(4)

1.504(5)

1.814(4)

1.523(5)

1.512(5)

1.793(4)

Cl(2)–Ru(2)–S(2)

Cl(2)–Ru(2)–N(2)

S(2)–Ru(2)–N(2)

S(2)–Ru(2)–C(25)

S(2)–Ru(2)–C(30)

N(2)–Ru(2)–C(26)

N(2)–Ru(2)–C(27)

Cl(2)–Ru(2)–C(28)

Cl(2)–Ru(2)–C(29)

C(43)–S(2)–C(36)

S(2)–C(36)–C(35)

C(36)–C(35)–N(2)

C(36)–C(35)–C(37)

Ru(2)–S(2)–C(36)

Ru(2)–N(2)–C(35)

88.53(4)

83.07(9)

81.45(9)

167.8(2)

142.2(2)

145.9(2)

165.5(2)

146.9(2)

164.4(2)

101.5(2)

107.1(3)

108.0(3)

113.9(3)

99.3(2)

164.5(2)

144.3(2)

149.5(2)

166.7(2)

150.2(2)

158.3(2)

106.3(3)

110.4(3)

107.6(4)

114.6(4)

100.8(2)

112.7(3)

117.0(2)

˚

Table 5. Selected bond lengths (A) and angles (deg) of com-

plex cation 17sa.

Distances

Angles

Ru(1)–Cl(1)

Ru(1)–S(1)

Ru(1)–N(1)

Ru(1)–C(1)

Ru(1)–C(2)

Ru(1)–C(3)

Ru(1)–C(4)

Ru(1)–C(5)

Ru(1)–C(6)

N(1)–C(11)

S(1)–C(12)

C(11)–C(12)

C(11)–C(13)

S(1)–C(19)

2.400(1)

2.400(2)

2.148(3)

2.190(4)

2.240(4)

2.216(4)

2.203(4)

2.199(4)

2.203(4)

1.491(5)

1.824(4)

1.533(5)

1.526(5)

1.784(4)

Cl(1)–Ru(1)–S(1)

Cl(1)–Ru(1)–N(1)

S(1)–Ru(1)–N(1)

S(1)–Ru(1)–C(1)

S(1)–Ru(1)–C(6)

N(1)–Ru(1)–C(2)

N(1)–Ru(1)–C(3)

Cl(1)–Ru(1)–C(4)

Cl(1)–Ru(1)–C(5)

C(19)–S(1)–C(12)

S(1)–C(12)–C(11)

C(12)–C(11)–N(1)

C(12)–C(11)–C(13)

Ru(1)–S(1)–C(12)

Ru(1)–N(1)–C(11)

91.43(3)

83.26(8)

81.42(9)

168.1(2)

135.4(2)

140.5(2)

169.3(2)

141.2(2)

166.1(2)

105.6(2)

110.2(3)

106.9(3)

111.5(3)

100.3(2)

114.9(2)

Fig. 2. Displacement ellipsoid plot (50% probability) of the

molecular structure of the η⁶-(p-cymene) complex cation 16.

Hydrogen atoms (except H11A), PF₆⁻, MeOH and CH₂Cl₂

have been omitted for clarity; only diastereomer 16as is

present in the crystal of [16][PF₆] examined; for selected

bond lengths and angles see Table 3.

(s) and sa η⁶-ligand syn (s) and R^ꢀanti (a) diastere-

omers were found in the solid state.

Attempts to react 14 and 15 with 11 (obtained by

in situ deprotonation of 10) to yield the correspond-

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Fig. 3. Displacement ellipsoid plot

(50 % probability) of the molecular

structures of the diastereomeric η⁶-

mesitylene complex cations 17as (left)

and 17sa (right) observed in the unit

cell of complex salt [17][PF₆]. Hydro-

gen atoms except H35A and H11A have

been omitted for clarity; for selected

bond lengths and angles 17as and 17sa

see Tables 4 and 5, respectively.

Fig. 4. Displacement ellipsoid plot (50 % probability) of

the molecular structures of the diastereomeric η⁶-mesitylene

Fig. 5. Displacement ellipsoid plot (50 % probability) of

the molecular structures of the diastereomeric η⁶-mesitylene

complex cations 19sa (left) and 19as (right) as observed

in the unit cell of the complex salt [₋19][PF₆]. Hydrogen

atoms (except H11A and H33A), PF₆and CH₂Cl₂have

been omitted for clarity; selected bond lengths and angles

are listed in Tables 8 and 9, respectively.

complex cations 18as (left) and 18sa (right) observed in the

unit cell of the complex salt [18][PF₆]. Hydrogen atoms ex-

cept H41A and H11A have been omitted for clarity; for se-

lected bond lengths and angles for 18as and 18sa see Tables 6

and 7, respectively.

ing β-aminothiolato η⁶-arene Ru(II) complexes re-

sulted only in product mixtures. To relate the reac-

tivity of 10 or 11 as potential thiolate precursors to

an alternative starting material, the prenyl functional-

ity of 13 was introduced as a designed leaving group.

However, the η⁶-mesitylene complex dimer 15 re-

acted with 13 to form the σ(N) : σ(S) β-amino prenyl

thioether η⁶-arene Ru(II) complex cation 19, which

could also be characterized by X-ray crystal structure

analysis (Fig. 5). Any attempt to convert 19 via allyl-

conjugative fragmentation to the desired thiolato com-

plex resulted also in mixtures of several compounds.

Comparable fragmentations were achieved by Bennett

and Goh [1g – j] and by van der Zeijden with even

more electron rich Ru(II) η⁵-Cp complexes [8c]. Com-

pounds 16 – 19 are air-stable in the solid state and in

solution. Of all crystals examined, the η⁶-(p-cymene)

species 16 crystallized always as the pure diastereomer

salt [16as][PF₆], whereas the η⁶-(mesitylene) complex

cations 17 – 19 formed 1 : 1 diastereomeric mixtures of

the as and the sa diastereomers in the unit cells of their

PF₆salts.

The stereochemical descriptors of the absolute con-

ﬁguration of the chiral Ru(II) centers used in this pa-

per follow the recommendations of Bu¨nzli-Trepp [9]

with the results: 16as – 18as (S_Ru, R_S, R) η⁶-ligand

anti (a) and R^ꢀsyn (s) in regard to benzylic Ph; 16sa –

18sa (R_Ru, S_S, R); 16aa – 18aa (S_Ru, S_S, R); 16ss – 18ss

(R_Ru, R_S, R). Note that for R^ꢀ= Prn the absolute con-

ﬁguration of the chiral sulfur center formally changes:

19as (S_Ru, S_S, R); 19sa (R_Ru, R_S, R); 19aa (S_Ru, R_S, R);

19ss (R_Ru, S_S, R).

As expected from the synthetic route applied, the ab-

solute conﬁguration of the chiral benzylic center of the

ligand backbone was conﬁrmed to be (R) in all cases.

Beyond the molecular details of the ruthenium com-

plex cations in the crystalline state, hydrogen bridgin₋g

between the coordinated amino groups and the PF₆

counteranions is observed for all four salts examined.

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128

I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

Table 8. Selected bond lengths (A) and angles (deg) of com- Table 10. Averaged angles (deg) φ_trans= X-Ru(II)-C(i)(η⁶-

˚

plex cation 19as.

arene) (X = N, S, Cl) of all particular diastereomeric η⁶-

arene complex cations 16 – 19 as an indicator of the trans

inﬂuence.

Distances

Angles

Ru(2)–Cl(2)

Ru(2)–S(2)

Ru(2)–N(2)

Ru(2)–C(24)

Ru(2)–C(25)

Ru(2)–C(26)

Ru(2)–C(27)

Ru(2)–C(28)

Ru(2)–C(29)

N(2)–C(33)

S(2)–C(34)

C(33)–C(34)

C(33)–C(35)

S(2)–C(41)

C(41)–C(42)

C(42)–C(43)

C(43)–C(44)

C(43)–C(45)

2.409(2)

Cl(2)–Ru(2)–S(2)

Cl(2)–Ru(2)–N(2)

S(2)–Ru(2)–N(2)

S(2)–Ru(2)–C(28)

S(2)–Ru(2)–C(29)

N(2)–Ru(2)–C(26)

N(2)–Ru(2)–C(27)

Cl(2)–Ru(2)–C(24)

Cl(2)–Ru(2)–C(25)

C(41)–S(2)–C(34)

S(2)–C(34)–C(33)

C(34)–C(33)–N(2)

C(34)–C(33)–C(35)

Ru(2)–S(2)–C(34)

Ru(2)–N(2)–C(33)

C(41)–S(2)–C(34)

S(2)–C(41)–C(42)

C(41)–S(2)–Ru(2)

C(41)–C(42)–C(43)

C(42)–C(43)–C(44)

C(42)–C(43)–C(45)

C(44)–C(43)–C(45)

88.35(5)

83.8(2)

81.7(2)

2.364(2)

2.147(4)

2.182(6)

2.193(5)

2.202(5)

2.220(5)

2.196(5)

2.230(6)

1.509(6)

1.836(5)

1.490(7)

1.512(7)

1.836(6)

1.492(8 )

1.310(10)

1.526(9)

1.492(10)

Complex

φ_trans

S

φ_trans

N

φ_transCl

155.6

154.6

154.9

155.4

16

17

18

19

156.1

153.3

155.3

155.2

156.8

155.3

157.4

157.0

162.7(2)

148.5(2)

161.0(2)

152.8(2)

160.1(2)

152.0(2)

100.5(3)

107.6(3)

108.0(4)

113.9(4)

98.8(2)

116.6(3)

100.5(3)

109.4(4)

112.7(2)

126.5(6)

120.6(6)

126.1(6)

113.3(6)

All bond lengths and angles are in the expected

range. An elongation of the S–CH₂and a shorten-

ing of the allyl (-CH₂–CH=C) bond lengths of 19as

and 19sa are indicative of a potentially labile prenyl

group. Although the S–CH₂bonds of 19as and 19sa

are arranged almost parallel to the alkene π-bonding

planes, the small variations of the bond lengths indicate

only a very weak stereoelectronic effect [6c – d] in the

sense of a σ*-π*-σ delocalization, which might be in-

ﬂuenced by crystal packing as well (Fig. 5, Tables 8, 9).

The C–N and C–S bonds are only slightly elon-

˚

gated. The average Ru–S bond length of 2.38 A com-

pares well to the ones of phosphine Ru(II)-η⁶-arene

˚

Table 9. Selected bond lengths (A) and angles (deg) of com-

complexes. Comparison of the bond angles φ_trans

=

plex cation 19sa.

Distances

X–Ru(II)–C(i)(η⁶-arene) (X = N, S, Cl) greater or

equal 150^◦reveal slight trans inﬂuences, but without

general tendencies (Table 10). Generally, thioethers are

much weaker σ donor and π acceptor ligands than

phosphines, and this general effect cannot be signiﬁ-

cantly inﬂuenced or modulated by variation of the sul-

fur substituent R^ꢀ.

Angles

Ru(1)–Cl(1)

Ru(1)–S(1)

Ru(1)–N(1)

Ru(1)–C(1)

Ru(1)–C(2)

Ru(1)–C(3)

Ru(1)–C(4)

Ru(1)–C(5)

Ru(1)–C(6)

N(1)–C(11)

S(1)–C(12)

C(11)–C(12)

C(11)–C(13)

S(1)–C(19)

C(19)–C(20)

C(20)–C(21)

C(21)–C(22)

C(21)–C(23)

2.399(2)

2.390(2)

2.127(4)

2.203(6)

2.210(5)

2.180(6)

2.189(6)

2.191(7)

2.237(6)

1.493(6)

1.821(5)

1.526(6)

1.521(7)

1.839(6)

1.472(8)

1.315(9)

1.501(9)

1.517(11)

Cl(1)–Ru(1)–S(1)

Cl(1)–Ru(1)–N(1)

S(1)–Ru(1)–N(1)

S(1)–Ru(1)–C(1)

S(1)–Ru(1)–C(6)

N(1)–Ru(1)–C(2)

N(1)–Ru(1)–C(3)

Cl(1)–Ru(1)–C(4)

Cl(1)–Ru(1)–C(5)

C(19)–S(1)–C(12)

S(1)–C(12)–C(11)

C(12)–C(11)–N(1)

C(12)–C(11)–C(13)

Ru(1)–S(1)–C(12)

Ru(1)–N(1)–C(11)

C(19)–S(1)–C(12)

S(1)–C(19)–C(20)

C(19)–S(1)–Ru(1)

C(19)–C(20)–C(21)

C(20)–C(21)–C(22)

C(20)–C(21)–C(23)

C(22)–C(21)–C(23)

91.88(5)

84.1(2)

81.8(2)

163.5(2)

146.1(2)

151.3(2)

162.6(2)

151.3(2)

158.3(2)

101.9(3)

110.6(3)

107.8(4)

111.5(4)

100.5(2)

115.3(3)

101.9(3)

111.7(4)

110.4(2)

128.9(6)

122.7(7)

123.0(6)

114.2(7)

It is remarkable that we found as and sa diastere-

omers with a 1 : 1 ratio in the unit cells of the PF₆

salts of the η⁶-mesitylene cations 17 – 19, whereas the

only other example with an alternative arene ligand, the

η⁶-(p-cymene) species 16, forms a deﬁned crystalline

phase with a single as diastereomer only. If we assume

an increased molecular fragment volume for the (η⁶-p-

cymene)Ru moiety as compared to (η⁶-mesitylene)Ru,

this ﬁnding for the crystalline state seems to ﬁt to the

CD and NMR spectroscopic results of the compounds

in solution, which point to a more pronounced inter-

action between the ﬁve-membered chelate ring sub-

stituents and the p-cymene ligand (vide infra).

In addition, [16][PF₆] and [19][PF₆] incorporate sol-

vent molecules in deﬁned stoichiometric ratios into

their crystal structures, which were also conﬁrmed by

elemental analysis. This and the repetition of structural

motifs in the crystals examined justify the assump-

CD and NMR studies of diastereomeric β-aminothio-

ether-chelated η⁶-arene complex cations in solution

If steric repulsion with respect to the η⁶-arene lig-

tion of an inherent preference of the diastereomers ob- and is regarded as the dominating factor for the ener-

served in the solid state.

getic preference of one or two particular diastereomers

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

129

Scheme 3. Diastereomer equilib-

ria of the complex cations 16 –

19 in solution; for numbering see

Scheme 2.

Fig. 6. CD spectra (MeOH, ambient tempera-

ture, c ∼ 10⁻⁶M); a) β-aminothioether deriva-

tives 5, 7 and 8; b) β-aminothioether-chelated

ruthenium(II) η⁶-arene cations 16 – 19.

over the four possible (as, aa, sa, ss), then the ener- oriented (arene)Ru and SR^ꢀmoieties, which are syn-

getic preference should decrease in the general order oriented for the aa diastereomers (Scheme 3).

as > sa ≥ aa > ss. This consideration is unambigu-

A close match of the CD spectra of complex

ously clear for the most preferred as and the most dis-

criminated ss diastereomers, but the relation between

sa and ss diastereomers is not that easily evaluated

on a qualitative level. Generally, the sa cases should

be slightly lower in energy than the aa diastereomers

as they minimize the axial repulsion between anti-

cations 16 – 19 and free β-aminothioether ligands 5,

7 and 9 in the range 250 – 300 nm (Fig. 6) are in-

dicative of small contributions of both, the coordinated

ruthenium metal and the sulfur atom stereocenters to

the chiroptical properties in that spectral range of the

asymmetric compounds. An equilibrium of diastere-

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130

I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

Table 11. Crystallographic data of 9, [16][PF₆]·(CH₂Cl₂)_0.5·(MeOH), [17][PF₆], [18][PF₆], and [19][PF₆]·(CH₂Cl₂)_0.5

.

9

[16][PF₆] (CH₂Cl₂)_0.5

·(MeOH)

[17][PF₆]

[18][PF₆]

19][PF₆] (CH₂Cl₂)_0.5

Emp. formula

Mol. weight

Color, shape

Crystal size, mm³

T, K

C₂₅H₂₅NO₃S₂

451.58

C_25.5H₃₄Cl₂F₆NOPRuS C₂₃H₂₇ClF₆NPRuS C₂₇H₂₉ClF₆NPRuS C_22.5H₃₂Cl₂F₆NPRuS

719.54

631.01

681.06

665.49

colorless, needle

yellow, platelet

yellow, block

orange, block

yellow, block

0.35×0.10×0.08 0.37×0.24×0.05

0.16×0.13×0.07 0.21×0.14×0.12 0.18×0.18×0.16

100

Crystal system

Space group

monoclinic

C2 (no. 5)

28.108(3)

5.2575(3)

15.758(2)

102.052(6)

2277.4(4)

4

monoclinic

C2 (no. 5)

19.170(2)

8.8851(5)

17.328(2)

97.250(9)

2927.8(5)

4

monoclinic

P2₁(no. 4)

10.1658(7)

12.3733(5)

20.161(1)

90.670(6)

2535.8(2)

4

monoclinic

P2₁(no. 4)

10.229(1)

10.759(1)

24.477(2)

93.626(6)

2688.4(4)

4

monoclinic

C2 (no. 5)

15.934(2)

15.537(2)

23.330(3)

104.67(2)

5587(2)

8

˚

a, A

˚

b, A

˚

c, A

β, deg

3

˚

V, A

Z

ρ, g cm⁻³(calc.)

1.317

0.261

952

1.632

0.904

1460

1.653

0.926

1272

1.683

0.880

1376

1.582

0.937

2696

µ, mm⁻¹

F(000), e

Abs. corr.

T_min; T_max

2 θ range, deg

Collected reﬂ.

Independent reﬂ.

multiple scans

(SADABS)

0.906 0.980

6.5 – 54.2

28956

numerical

(Gauss integration)

0.801; 0.965

5.7 – 56.0

26506

multiple scans

(SADABS)

0.813; 0.940

6.8 – 54.2

50197

numerical

(Gauss integration) (SADABS)

0.844; 0.905

7.2 – 54.2

50387

multiple scans

0.740; 0.860

6.0 – 52.8

55165

5006

6830

11067

11811

11281

Obs. reﬂ. [F₀≥ 4σ(F)] 4220

5283

350

0.00433

0.0897

1.036

8952

619

0.0382

0.0782

8392

691

0.0382

0.0819

0.834

9707

670

0.0445

0.1088

1.044

No. ref. param.

R₁[F₀≥ 4σ(F)]

wR₂(all data)

GooF (F²)

282

0.0418

0.0930

1.024

0.919

Absolute structure

parameter x

−0.05(7)

−0.05(3)

−0.02(2)

0.01(3)

−0.01(3)

Max.; min. res₋. ₃electron 0.47; −0.34

0.62; −0.75

0.46; −0.41

0.96; −0.52

1.02; −0.85

˚

density, e A

omers generated by these two centers and the preser- their as and sa as well as of their aa and ss diastereo-

vation of the absolute conﬁguration of the particular mers.

ligand backbones would be a good explanation for this

The NMR spectrum of the η⁶-(p-cymene) cation 16

experimental ﬁnding, and this agrees with the NMR re- consists of two sets of signals belonging to two di-

sults (vide infra). A slight bathochromic shift of the ab- astereomers. Their intensity ratio of 1 : 0.32 is indepen-

sorption of the complex cations accounts for the com- dent of the work-up procedure applied, a good hint to

plexation of the chelate ligands. Only for 16 a positive a chemical equilibrium in solution as the reason. The

medium Cotton effect is observed in the 380 – 410 nm ratio is only slightly inﬂuenced by temperature (Fig. 7)

region of the Ru(II) transitions [4e, 10], whereas for the and by solvent (Table 11), however, signiﬁcant line

η⁶-mesitylene complexes 17 – 19 the Cotton effects in broadening is observed at ambient and higher tempera-

that region are much weaker, but also positive. This ture which is absent at −30 ^◦C. No coalescence of sig-

points to the dominance of one enantiomer with the nals could be observed up to +70 ^◦C. As for the mesity-

chiral Ru(II) center of 16 in the sample. As the benzylic lene species 17 – 19 (vide infra), the effect is related to

ligand backbone C* stereocenter is stable and identical an increasing exchange rate between the diastereomers

◦

with that in the ligand used, it is left to the chiral sulfur of 16. At −30 C the aromatic η⁶-(p-cymene) pro-

center of 16 to be affected by an epimerization equilib- tons split completely into two sets of four doublets for

rium in solution. Complementarily, the corresponding each diastereomer due to their planar diastereotopicity

weak Cotton effects for 17 – 19 indicate an epimeriza- (Fig. 7). At the same time no signiﬁcant signal changes

tion equilibrium at both, the chiral Ru(II) and the sulfur are observable for the chelate ring phenyl substituents,

center due to the pseudo-enantiomeric relationship of thus free rotation around their C*–C and S*–C bonds,

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

131

Fig. 7. Aromatic η⁶-(p-cymene) proton

region of the ¹H NMR spectra of 16

(CDCl₃, 400 MHz); a) ambient temper-

ature; b) −30 ^◦C; for numbering see

Scheme 4.

Scheme 4. Diastereomers of 16as

and 16aa in equilibrium; a) Num-

bering of protons not affected

upon NOE irradiation; b) NOE

responses and numbering of pro-

tons affected by irradiation of

the p-methyl group of the η⁶-(p-

cymene) ligand.

respectively, is assumed for both of them. NOE ir- of the two sets of the corresponding (2,6)-protons of

radiations at the two p-methyl singlets of the η⁶-(p- the arene ligand and of the ortho protons of the thio-

cymene) ligand (Scheme 4, Fig. 8) lead to the response phenyl ring only. No NOE response could be observed

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132

I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

Fig. 9. Aromatic η⁶-mesitylene proton region (δ = 5 – 6) of

the ¹H NMR spectra of 17 (CDCl₃, 400 MHz); a) at −30 ^◦C;

b) at ambient temperature.

aa diastereomer, so that the as should be energetically

preferred over the aa diastereomer. Thus, the signals

belonging to the major species present in solution are

1

assigned to the as diastereomer of 16. All other H

resonances were assigned by J(H)J(H)-COSY, by cou-

Fig. 8. NOE irradiation on the p-methyl groups of the η⁶-(p-

cymene) ligands of a) 16as and b) 16aa; for numbering see

Scheme 4.

pling constants and/or similarity relationships, which

were then correlated to the signals in the ¹³C NMR

spectrum by DEPT and HMQC experiments.

for the protons of the ligand backbone phenyl sub-

stituents (7.34 ppm, m).

A completely different situation is observed for the

η⁶-mesitylene species 17 – 19 in solution (Fig. 9). The

Evidence is obtained from the CD spectrum of 16 aromatic protons of the π-mesitylene ligand (5.2 –

that both diastereomers must have the same absolute 5.8 ppm) form singlets of different intensity for each

conﬁguration at the Ru(II) center, leaving the choice diastereomer distinguishable by NMR due to its C₃

only to the as + aa or the sa + ss pairs of diastere- symmetry. A hindered rotation of the π-arene ligands

omers. Therefore the absence of a NOE response of can be ruled out as the reason for that ﬁnding, as no in-

the ligand backbone phenyl substituents suggests that tensity ratios or temperature dependence effects were

these phenyl rings are in anti position to the η⁶-(p- observed, which would ﬁt to such a model. As a conse-

cymene) ligand. This leaves ﬁnally the choice to the quence, free rotation of the π-mesitylene ligands even

as + aa pair of diastereomers only. The A^1,2repulsion at low temperature has to be assumed. The same mani-

of the thiophenyl moiety from the coordinated arene fold of proton NMR singlets appears for the mesitylene

must be expected to be weaker for the as than for the methyl protons (1.5– 2.4 ppm), and integration of both

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

133

sets of signals can be principally used for the deter- Three of them were reacted successfully with two di-

mination of the diastereomer ratios. Three broadened µ-chloro-bis{chloro[η⁶-arene]ruthenium(II)} deriva-

singlets are generally observable at ambient tempera- tives, resulting in the title complex salts. The complex

ture and four sharper ones at low temperature. If the cations exhibit three stereocenters, the ruthenium and

four lines are related to the NMR-distinguishable di- sulfur atoms and the chiral benzylic carbon atom of the

astereomers of 17 – 19, the observation ﬁts to struc- chelate ligand backbone. The η⁶-p-cymene species 16

tures with two conﬁgurationally labile stereocenters, forms two diastereomers only with an epimerized sul-

both in equilibrium with their optical antipodes. The fur atom, but a deﬁned ruthenium stereocenter. The

broadened and partially collapsed ambient temperature chiral benzylic carbon atoms of the chelate ligands

spectra suggest increasing exchange rates between di- are completely stable for all species investigated un-

astereomers, however, no rapid exchange limit spec- der all conditions applied so far. The relative diastere-

tra could be reached at elevated temperatures. As 17 – omer concentrations in solution depend mainly on the

19 exhibit three stereocenters each, one of them is ex- spatial requirements of the η⁶-arene ligand rather than

cluded from forming the observed diastereomers. As on the chiral carbon atom or thioether substituents

for the CD spectra, we assign this to the designed chi- of the chelate ligand. The η⁶-p-cymene ligand of 16

ral benzyl carbon atom of the chelate ring backbone, is inducing a dominating A^1,2-repulsion of the N∩S

which was identiﬁed exclusively in its R conﬁguration chelate ligand S*-phenyl moiety and forces it exclu-

in the solid state.

sively into the anti positions of 16as and 16aa diastere-

omers with their common (S)-conﬁguration of the chi-

ral Ru(II) centers. In agreement with the spectroscopic

results, only the energetically most preferred diastere-

omer 16as has been observed in the crystalline state al-

lowing the determination of its absolute conﬁguration.

Both, the ruthenium and sulfur stereocenters of the

complexes epimerize in solution into a mixture of four

NMR distinguishable as, sa, aa, and ss diastereomers

in an equilibrium for the smaller η⁶-mesitylene ligands

of cations 17 – 19. Again, the spectroscopic ﬁndings

are conﬁrmed by the results of X-ray structure studies.

All single crystals of the PF₆salts of cations 17 – 19

investigated contain as and sa diasteromers in the ra-

tio 1 : 1 and allowed the determination of their absolute

structure parameters in the solid state.

An example is given for 17 in CDCl₃(Fig. 9).

Four singlets A – D with an intensity ratio of

1 : 0.6 : 0.5: 0.05 appear at −30 ^◦C. They are all broad-

ened, and C + D collapse into one line at r. t., yield-

ing an intensity ratio of 1.0 : 0.36 : 0.29. An increase of

temperature by 50 ^◦C thus caused only a small change

of the relative diastereomer ratios of 17.

As a consequence, the four identiﬁed arene proton

signals A – D of the mesitylene ligand of 17 can be re-

lated to the four possible diastereomers 17as, sa, aa,

and ss. The most intense signal A which is located at

the low-ﬁeld side of the π-arene NMR region can be

assigned to the energetically most favored species 17as

with its minimal axial repulsion effects between the

two substituents of the ﬁve-membered chelate ring and

the mesitylene ligand, and the smallest signal D must

belong to the most disfavored diastereomer 17ss. On

the other hand, no clear relations between signals B

and C and 17sa and 17aa, respectively, can be eluci-

dated due to their small differences, both in intensity

and chemical shift. The effect was studied in different

solvents with no principal differences between them.

In conclusion, from the NMR spectroscopic results

evidence has been found for low inversion barriers for

both, the chiral sulfur center as well as the ruthenium

atom in its chiral [Ru(η⁶-arene)(N∩S)Cl] coordination

sphere, and for a free rotation of the η⁶-bonded arene

ligands.

With respect to the long term targets of these investi-

gations, compounds 16 and 17 were tested as catalysts

in the transfer hydrogenationof acetophenonewith iso-

propanol under basic conditions [3b – j]. They are ac-

tive but not enantioselective.

Experimental Section

General

All reactions were carried out under N₂by using

conventional Schlenk techniques. Liquid reagents were

generally added with disposable plastic syringes. All

work-ups were performed in air. Complex cations 16 – 19

are airstable in the solid state and only slightly airsensitive

in solution. Except 11, all other substances prepared are

also airstable. Solvents and chemicals were purchased

from Acros, Aldrich, Strem, and Merck. Solvents, Et₃N

Conclusions

Five enantiopure β-aminothioethers were obtained

by different routes orientated on literature protocols. and mesyl chloride were dried and distilled under N₂

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134

I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

prior to use: THF over sodium/benzophenone; MeOH r. t. were added t-BuOK (3.801 g, 33.87 mmol) and then 3

and n-PrOH over magnesium, CH₂Cl₂and Et₃N over (5.100 g, 16.17 mmol). Potassium mesylate started to pre-

calcium hydride. All other solvents and chemicals were cipitate immediately. After stirring for 12 h at r. t., 30 mL

used as received. (–)-(R)-2-Amino-2-phenylethanol 1 [6a], 36 % HCl was added, and the mixture was stirred for another

(–)-(2R)-2-[(1^ꢀ,1^ꢀ-dimethylethoxy-carbonyl)amino]-2-phen-

30 min before concentration in vacuo (max. 60 ^◦C/10 mbar).

ylethanol 2 [6b], (4R)-4-phenyl-2-oxalodinone 8 [7a, b], The residue was suspended in 40 % NaOH and the aqueous

di-µ-chloro-bis[chloro{η⁶-[1-methyl-4-(methylethyl)benz-

phase extracted twice with CH₂Cl₂. The combined organic

ene]}ruthenium(II)] 14 [8a, b] and di-µ-chlorobis{chloro- layers were dried (Na₂SO₄) and concentrated to get 3.926 g

[η⁶-(1,3,5-trimethylbenzene)]ruthenium(II)} 15 [8a] were (> 99 %) of 4 as a slightly yellowish oil which contains traces

prepared as reported. Flash column chromatography (FC): of 8.

silica gel F 60 (Fluka or Merck). Thin layer chromatography

(TLC): Merck F 60 silica plates with a 364 nm ﬂuorescence

indicator; primary amines were identiﬁed by spraying

with a ninhydrine soln. and heating of the TLC plates.

Melting points: Bu¨chi 530 melting point apparatus; not

corrected. Polarimetric measurements: Perkin-Elmer 341

polarimeter. Circular dichroism measurements: JASCO

J-710 spectropolarimeter. NMR spectra: Jeol FT-JNM-EX

270 (270 MHz), Bruker AMX 300 (300 MHz), Jeol

FT-JNM-LA 400 (400 MHz) and Jeol A 500 (500 MHz)

spectrometers; in deuterated solvents and referenced to

the residual proton signal of the particular solvent. ¹H and

¹³C NMR signals were generally assigned by utilizing

¹J(H)¹J(H)-COSY, DEPT and HMQC techniques. Mass

spectra: Varian MAT 212 spectrometer. Elemental analyses:

Carlo Erba elemental analyzer Model 1108.

b) Representative procedure: After dissolving Na

(661 mg, 28.75 mmol) in n-PrOH (30 mL), benzylthiol

(5.20 mL, 44.29 mmol) and solid 8 (2.062 g, 12.64 mmol)

were added at r. t. The soln. was heated for 24 h under reﬂux.

After cooling to r. t., the soln. was poured into a threefold

volume of 40 % NaOH and extracted once with CH₂Cl₂.

The organic phase was washed twice with 40 % NaOH

to remove excess thiol, dried (Na₂SO₄) and concentrated:

2.706 g (88 %) of crude product as turbid yellow oil, which

was pu_◦riﬁed by Kugelrohr distillation: 2.586 g (84 %; b. p.

> 160 C C/0.0001 mbar) of 4 as clear and colorless oil. –

[α]²_D³= −46.2 (CH₂Cl₂, c = 0.0017). – ¹H NMR (CDCl₃,

270 MHz): δ = 7.34 – 7.19 (2 m, 10H, Ph), 3.99 (dd, ³J =

8.9, ³J = 4.3 Hz, 1H, -CH-), 3.65 (s, 2H, -S – CH₂-Ph), 2.73

(dd, ²J = 13.5, ³J = 4.3 Hz, 1H, -CH(NH₂)–CH₂-), 3.53

(dd, ²J = 13.5, ³J = 8.9 Hz, 1H, -CH(NH₂)–CH₂-), 1.77

1

(br s, 2H, -NH₂). – ¹³C{ H} NMR (CDCl₃, 68 MHz): δ =

(–)-(1R)-1-[(1^ꢀ,1^ꢀ-Dimethylethoxycarbonyl)amino]-2-

(methylsulfonyl)oxy-1-phenylethane (3)

144.26 (C_ipsoof Ph-CH-), 138.04 (C_ipsoof -S – CH₂-Ph),

128.69 (C_mof Ph-CH-), 128.30 (C_oof -S – CH₂-Ph), 128.29

(C_mof -S – CH₂-Ph), 127.16 (C_mof Ph-CH-), 126.85 (C_p

of -S – CH₂-Ph), 126.14 (C_oof Ph-CH-), 54.60 (-CH-),

41.16 (-CH(NH₂)–CH₂-), 36.40 (-S–CH₂-Ph). – FD-MS

(pos.; CH₂Cl₂): m/z (%) = 244 (100) [M + H]⁺. A correct

elemental analysis could not be obtained.

To 2 (24.86 g, 105 mmol)_◦and Et₃N (22.0 mL, 158 mmol)

in CH₂Cl₂(300 mL) at 0 C, within 10 min mesyl chlo-

ride (10.0 mL, 129 mmol) was added dropwise. The mix-

ture was stirred for 16 h in the cooling bath for defrosting

to r. t. The soln. was poured into a sat. NaHCO₃soln., and

the organic phase washed once with brine, dried (MgSO₄),

and concentrated to afford 29.53 g (89 %) of 3 as a slightly

yellowish powder. For prolonged _◦times, the solid product

(+)-(1R)-1-Phenyl-2-(phenylthio)ethylamine (5)

a) According to the above procedure from thiophenol

(2.00 mL, 21.31 mmol), t-BuOK (2.353 g, 20.97 mmol)

and 3 (3.047 g, 9.66 mmol) in MeOH (20 mL) for 18 h.

Reaction monitored with FD-MS (reaction mixture diluted

with CH₂Cl₂): m/z (%) = 329 (100) [Ph-CH[NH(BOC)]-

CH₂-SPh]⁺: 2.289 g of crude 5 as a yellow oil, which con-

tained ca. 20 % 8 (NMR). The crude product was recrystal-

lized twice from hot EtOH layered with pentanes by slowly

should be stored at 0 ^◦C. M. p. 82 C starting dec. – [α]²_D³

=

−29.2 (CH₂Cl₂, c = 0.0082). – ¹H NMR ([D₆]DMSO,

270 MHz): δ = 7.71 (br pseudo d, 1H, -NH(BOC)), 7.36 –

7.26 (m, 5H, Ph), 4.85 (not res. dd, 1H, -CH-), 4.23 (2

not res. dd, 2H, -CH₂-), 3.14 (s, 3H, -SO₂CH₃), 1.34 (br

1

s, 9H, -C(CH₃)₃). – ¹³C{ H} NMR ([D₆]DMSO, 68 MHz,

dominant rotamer): δ = 154.85 (-CO-), 138.78 (C_ipsoof

Ph), 128.30 (C_mof Ph), 127.53 (C_pof Ph), 126.93 (C_oof

Ph), 78.22 (-C(CH₃)₃), 71.30 (-CH₂-), 53.30 (-CH-), 36.86

(-SO₂CH₃), 28.21 (-C(CH₃)₃). – FD-MS (pos.; CH₂Cl₂):

m/z (%) = 163 (100) [C₉H₉NO₂]⁺, 316 (71) [M]⁺. A cor-

rect elemental analysis could not be obtained.

◦

cooling down to −30 C; this and recrystallization of the

combined mother liquors afforded overall 1.559 g (70 %) of 5

as white crystals.

b) The original procedure was modiﬁed [7c, d]. According

to the above procedure from Na (290 mg, 12.61 mmol), thio-

phenol (2.00 mL, 21.31 mmol) and 8 (604 mg, 3.70 mmol)

in n-PrOH (20 mL) for 12 h under reﬂux: 790 g (93 %) crude

(–)-(1R)-1-Phenyl-2-[(phenylmethyl)thio]ethylamine (4)

a) Representative procedure: To benzylthiol (4.00 mL, product as brownish microcrystals, recrystallized from EtOH

34.07 mmol) in THF (100 mL) and MeOH (30 mL) at and some drops of hexanes at −30 ^◦C: 636 mg (75 %) of 5. –

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

135

M. p. = 72 – 73 ^◦C (lit: 69 – 70 ^◦C). – [α]_D²³= +29.4 (CH₂Cl₂, (CDCl₃, 270 MHz): δ = 7.74 – 7.66 (m, 4H, H-C(5,6,7,8)

c = 0.0042); [α]²_D³(lit. for (S)-enantiomer) = −24.2 (CHCl₃, of β-Naph), 7.45 – 7.14 (series of m, 8H, Ph, β-Naph), 4.07

c = 1.00). NMR and MS spectra of 5 in full agreement with (dd, ³J = 9.3, ³J = 4.0 Hz, 1H, -CH-), 3.34 (dd, ²J =

those reported [7c, d].

13.4, ³J = 4.0 Hz, 1H, -CH₂-), 3.05 (dd, ²J = 13.4, ³J =

1

9.3 Hz, 1H, -CH₂-), 1.64 (br s, 2H, -NH₂). – ¹³C{ H} NMR

(–)-(1R)-1-Phenyl-2-(1^ꢀ-naphthylthio)ethylamine (6)

(CDCl₃, 68 MHz): δ = 144.21 (C_ipsoof Ph), 133.65 (C(8a)

of β-Naph), 133.11 (C(2) of β-Naph), 131.81 (C(4a) of β-

Naph), 128.57 (C_mof Ph), 128.50 (C(4) of β-Naph), 127.64

(C_pof Ph), 127.56 (C(8) of β-Naph), 127.55 (C(5) of β-

Naph), 127.03 (C(6,7) of β-Naph), 126.55 (C(1) of β-Naph),

126.34 (C_oof Ph), 125.76 (C(3) of β-Naph), 54.70 (-CH-),

43.71 (-CH₂-). – FD-MS (pos.; CH₂Cl₂): m/z (%) = 280

(100) [M + H]⁺. A correct elemental analysis could not be

obtained.

According to the above procedure from α-thionaphthol

(3.03 mL, 21.74 mmol), t-BuOK (2.445 g, 21.79 mmol)

and (6.833 g, 21.67 mmol) 3 in MeOH (20 mL) for 20 h:

5.632 g (93 %) of crude 6 as a brown turbid oil containing

traces of 8 (NMR), which was puriﬁed twice by FC [gra-

dient elution with hexanes/CH₂Cl₂/MeOH 1 : 1 : 0 (→ im-

purities) and then with 10 : 10 : 1 (→ 6)]: 3.191 g (53 %;

R_f= 0.01 [TLC, hexanes/CH₂Cl₂1 : 1], R_f= 0.28 [TLC,

hexanes/CH₂Cl₂/MeOH 10 : 10 : 1]) 6 as yellowish oil with

traces of impurities (NMR). – [α]²_D³= −5.5 (CH₂Cl₂, c =

0.0195), [α]²_D³= −11.8 (CHCl₃, c = 0.1992). – ¹H NMR

(CDCl₃, 270 MHz): δ = 8.37 (pseudo d, 1H, H-C(5 or 8) of

α-Naph), 7.81 – 7.16 (series of m, 11H, Ph, α-Naph), 4.01

(–)-(1R)-1-Phenyl-2-(1^ꢀ-naphthylthio)ethylammonium

4-methylphenyl-sulfonate (9)

From a saturated solution of crude 6 (3.409 g, ca.

12.20 mmol) and p-tosic acid monohydrate (2.339 g,

◦

3

(dd, J = 9.4, J = 4.0 Hz, 1H, -CH-), 3.27 (dd, ²J = 13.1,

12.30 mmol) in EtOH at −30 C as white needles. 1.715 g

³J = 4.0 Hz, 1H, -CH₂-), 3.03 (dd, J = 13.1, J = 9.4 Hz,

2

3

(31 %) of crystalline 9 was isolated after recrystalliz_◦ation

(X-ray crystal structure analysis). – M. p. = 169 – 170 C. –

[α]²_D³= +14.0 (MeOH, c = 0.0053). – ¹H NMR ([D₆]DMSO,

300 MHz): δ = 8.50 (br s, 3H, -NH⁺₃), 8.25 – 7.27 (series of

m, 12H, Ph, α-Naph), 7.89 (d, ²J = 8.3 Hz, 2H, H-C(3,5)

1H, -CH₂-), 1.78 (br s, 2H, -NH₂). – ¹³C{ H} NMR δ =

1

(CDCl₃, 68 MHz): 143.86 (C_ipsoof Ph), 133.62 (C(1) of

α-Naph), 132.69 (C(4a) of α-Naph), 132.66 (C(8a) of α-

Naph), 128.35 (C(5) of α-Naph), 128.30 (C(8) of α-Naph),

128.16 (C_mof Ph), 127.21 (C_pof Ph), 127.09 (C(3) of α-

Naph), 126.18 (C(6) of α-Naph), 126.05 (C_oof Ph), 125.94

(C(7) of α-Naph), 125.22 (C(4) of α-Naph), 124.73 (C(2)

of α-Naph), 54.33 (-CH-), 43.85 (-CH₂-). – FD-MS (pos.;

CH₂Cl₂): m/z (%) = 280 (100) [M + H]⁺. A correct elemen-

tal analysis could not be obtained.

of p-TolSO⁻₃), 7.08 (d, ²J = 8.3 Hz, 2H, H-C(2,6) of p-

−

3

TolSO₃), 4.39 (dd, J = 8.6, J = 6.0 Hz, 1H, -CH-), 3.61

(dd, ²J = 13.6, ³J = 6.0 Hz, 1H, -CH₂-), 3.51 (dd, ²J = 13.6,

³J = 8.6 Hz, 1H, -CH₂-), 2.29 (s, 3H, -CH₃of p-TolSO₃⁻). –

¹³C{ H} NMR ([D₆]DMSO, 75 MHz): δ = 145.48 (C_ipso

1

of Ph), 137.74 (C(1) of p-TolSO⁻₃), 136.12 (C(4) of p-

TolSO⁻₃), 133.76 – 124.26 (Ph, α-Naph, p-TolSO⁻₃), 53.51

(-CH-), 37.04 (-CH₂-), 20.76 (-CH₃of p-TolSO⁻₃). A cor-

rect elemental analysis could not be obtained.

(+)-(1R)-1-Phenyl-2-(2^ꢀ-naphthylthio)ethylamine (7)

a) According to the above procedure from β-thionaphthol

(1.690 g, 10.55 mmol), t-BuOK (1.183 g, 10.54 mmol) and 3

(2.997 g, 9.50 mmol) in MeOH (20 mL) for 19 h. Reac-

tion monitored with FD-MS (reaction mixture diluted with

CH₂Cl₂): m/z (%) = 379 (100) [Ph-CH[NH(BOC)]-CH₂-

S(β-Naph)⁺]: 2.344 g of crude 7 as a brown oil, contain-

ing ca. 20 % 8 (NMR). The crude product was recrystallized

three times from a minimum amount of hot CHCl₃layered

with the double amount of pentane, cooled slowly from r. t.

down to −30 ^◦C: 757 mg (29 %) of 7 with traces of 8.

(–)-(2R)-2-Amino-2-phenylethanethiol hydrochloride (10)

To a deep blue soln. of Na (1.861 g, 80.95 mmol) in liq-

◦

uid NH₃(165 mL) at −80 C were canulated within 2 min

from a Schlenk ﬂask 4 (4.036 g, 16.58 mmol) and t-BuOH

(1.548 g, 20.89 mmol) dissolved in THF (40 mL). The blue

soln. was stirred for 45 min ﬁrst inside the cooling bath, then

for 1 h outside until the reaction was quenched with excess

of ammonium chloride. NH₃was evaporated with nitrogen

b) According to the above procedure from Na (642 mg, gas, the residue suspended in EtOH, acidiﬁed to pH = 1 – 2

27.93 mmol), β-thionaphthol (7.519 g, 56.92 mmol) and 8 with 36 % HCl and the soln. ﬁltered off from NaCl. The clear

(1.064 g, 6.52 mmol) in ⁿPrOH (40 mL) for 18 h un- soln. was evaporated to dryness, the white residue dissolved

der reﬂux. 3.652 g of crude 7 was isolated as a yellow- in CH₂Cl₂/iPrOH/MeCN 1 : 1 : 1 and ﬁltered off from resid-

ish solid. The crude product was puriﬁed twice by FC ual NaCl again. After solvent evaporation the crude product

(hexanes/CH₂Cl₂/MeOH = 10 : 10 : 1) and then recrystal- was dissolved in CH₂Cl₂, precipitated with Et₂O, ﬁltered off

lized twice as described above: 475 mg [26 %; R_f= 0.38 and dried (P₂O₅, vacuum): 2.389 g (76 %) of 10 as an almost

◦

(TLC)] of 7 as brownish microcrystals. – M. p. = 98 – colorless powder. – M. p. = 153 – 155 C. – [α]²_D³= −7.5

◦

99 C. – [α]²_D³= + 63.7 (CH₂Cl₂, c = 0.0029). – ¹H NMR (MeOH, c = 0.00296). – ¹H NMR ([D₆]DMSO, 270 MHz):

Unauthenticated

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136

I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

δ = 8.77 (br s, 3H, -NH⁺₃), 7.53 – 7.10 (m, 5H, Ph), 4.32 (not (0.82 mL, 6.99 mmol). After stirring for 19 h at r. t. 2 mL

res. dd, 1H, -CH-), 3.34 (s, 1H, -SH), 3.08 – 2.85 (2 not res. 36 % HCl was added, the soln. stirred for 10 min and con-

1

dd, 2H, -CH₂-). – ¹³C{ H} NMR ([D₆]DMSO, 68 MHz): centrated in vacuo (max. 60 ^◦C/10 mbar). The slurry was sus-

δ = 136.33 (C_ipsoof Ph), 128.62 (C_pof Ph), 128.51 (C_mof pended in aqua dest., brought to pH = 14 with 40 % NaOH,

Ph), 127.58 (C_oof Ph), 56.35 (-CH-), 27.91 (-CH₂-). A cor- and the aqueous phase extracted twice with Et₂O. The com-

rect elemental analysis could not be obtained.

bined organic layers were dried (Na₂SO₄) and concentrated:

1.369 g (99 %) nearly pure 13 as an orange oil. Spectroscopic

data see below.

NMR characterization as (–)-(2R)-2-amino-2-phenylethane-

thiol (11)

b) To 12 (1.201 g, 4.74 mmol) and t-BuOK (585 g,

5.21 mmol) in THF (35 mL) was added prenyl bro-

mide (0.66 mL, 5.62 mmol). After stirring for 19 h at

r. t. 10 mL 36 % HCl was added, the soln. stirred for

40 min (open ﬂask) before work-up as described above:

1.006 g (96 %) nearly pure 13 as slight brownish oil. Pu-

riﬁcation: FC (hexanes/CH₂Cl₂/MeOH 10 : 10 : 1): 831 mg

[34 % average; R_f= 0.37 (TLC)] 13 as yellowish oil. –

[α]²_D³= −38.1 (CHCl₃, c = 0.114). – ¹H NMR (CDCl₃,

270 MHz): δ = 7.33 – 7.24 (m, 5H, Ph), 5.20 (pseudo t,

An analytical aliquot of 10 mixed with Na₂CO₃in MeOH

(ca. 3 mL) and aqua dest. (0.1 mL) was evaporated to dry-

ness, the residue dissolved in CDCl₃, ﬁltered and dried. –

¹H NMR (CDCl₃, 270 MHz): δ = 7.40 – 7.15 (m, 5H, Ph),

4.26 (dd, ³J = 9.2, ³J = 4.0 Hz, 1H, -CH-), 3.01 (dd,

²J = 13.4, ³J = 4.0 Hz, 1H, -CH₂-), 2.78 (dd, ²J = 13.4,

³J = 9.2 Hz, 1H, -CH₂-), 1.76 (2 br s, 3H, -SH, -NH₂). –

1

¹³C{ H} NMR (CDCl₃, 68 MHz): δ = 143.87 (C_ipsoof Ph),

128.55 (C_mof Ph), 127.45 (C_pof Ph), 126.42 (C_oof Ph),

54.34 (-CH-), 43.58 (-CH₂-).

3

1H, -CH=C(CH₃)₂), 4.05 (dd, ³J = 9.2, J = 4.04 Hz, 1H,

-CH-), 3.11 (m, 2H, -CH₂–CH=C(CH₃)₂), 2.78 (dd, ²J =

13.4, ³J = 4.0 Hz, 1H, -CH(NH₂)–CH₂-), 2.59 (dd, ²J =

13.4, ³J = 9.2 Hz, 1H, -CH(NH₂)–CH₂-), 1.76 (s, 2H, -NH₂),

1.71 (not res. d, 3H, -CH=C(CH_3cis)(CH₃)), 1.64 (partly

(–)-(2R)-[(1^ꢀ,1^ꢀ-Dimethylethoxycarbonyl)amino]-2-phenyl-

ethanethiol (12)

1

res. d, 3H, -CH=C(CH₃)(CH_3trans)). – ¹³C{ H} NMR

To KSAc (3.815 g, 33.40 mmol) in MeOH (50 mL) and

THF (50 mL) was added 3 (7.063 g, 22.39 mmol), the sus-

pension stirred for 24 h at r. t., then saturated for 10 min

with NH_3(gas)and stirred overnight. After concentration, the

residue was suspended in EtOAc, washed once with 1 % HCl

and then three times with brine. The organic phase was

dried (MgSO₄), concentrated to afford 4.146 g crude prod-

uct containing considerable amounts of 8 (NMR), and pu-

riﬁed by FC [applied as solid; gradient elution with hex-

anes/EtOAc 2 : 1 (→ 12), then with CH₂Cl₂(→ 8)]: 2.212 g

[40 %; R_f= 0.41 (TLC, hexanes/EtOAc 2 : 1)] of 12 as

a yellowish powder and 225 mg [6 %; R_f= 0.07 (TLC,

(CDCl₃, 68 MHz): δ = 144.47 (C_ipsoof Ph), 135.04

(-CH=C(CH₃)₂), 128.25 (C_mof Ph), 127.08 (C_pof

Ph), 126.11 (C_oof Ph), 120.39 (-CH₂–CH=C(CH₃)₂),

54.82 (-CH(NH₂)–CH₂-), 41.10 (-CH(NH₂)–CH₂-), 29.63

(-CH₂–CH=C(CH₃)₂), 25.60 (-CH=C(CH_3cis)(CH₃)), 17.74

(-CH=C(CH₃)(CH_3trans)). – FD-MS (pos.; CH₂Cl₂): m/z

(%) = 222 (100) [M + H]⁺. A correct elemental analysis

could not be obtained.

6

[(+)-(R_Ru, 1^ꢀꢀR)-Chloro-η -[1-methyl-4-(1^ꢀ-methylethyl)-

benzene]-σ(N):σ(S)-[1^ꢀꢀ-phenyl-2^ꢀꢀ-(phenylthio)ethyl-

hexanes/EtOAc 2 : 1)] of 8. – M. p. = 144 ^◦C. – [α]_D²³

=

amino]ruthenium(II)] hexaﬂuorophosphate, [16][PF ]

6

−47.3 (CH₂Cl₂, c = 0.0030). – ¹H NMR ([D₆]DMSO,

270 MHz): δ = 7.29 – 7.18 (m, 5H, Ph), 4.75 – 4.46 (partly

res. dd, 1H, -CH-), 3.14 – 2.97 (partly res. dd, 2H, -CH₂-),

2.28 (s, 1H, -SH), 1.29 – 1.11 (2 br s of rotamers, 9H, -

Representative procedure: In MeOH (25 mL) 14 (606 mg,

0.990 mmol) and 5 (471 mg. 2.054 mmol) were stirred at r. t.

until they were completely dissolved (40 min; → clear yel-

low soln.). After addition of NaPF₆(587 mg, 3.495 mmol),

the mixture was stirred for 17 h at r. t., concentrated, the

residue dissolved in CH₂Cl₂and ﬁltered. After concentra-

tion the product was crystallized from a saturated solution

C(CH₃)₃). – ¹³C{ H} NMR ([D₆]DMSO, 75 MHz, at least

1

3 rotamers): δ = 154.94 (-CO-), 142.34 (C_ipsoof Ph), 128.33

(C_mof Ph), 127.19 (C_pof Ph), 126.27 (C_oof Ph), 77.98 (-

C(CH₃)₃), 66.98 (-CH-) 54.08 (-CH-), 34.85 (-CH₂-), 30.47

(-C(CH₃)₃), 28.15 (-C(CH₃)₃), 25.07 (-C(CH₃)₃). – FD-MS

(pos.; CH₂Cl₂): m/z (%) = 504 (100) [2M − 2H]⁺. A correct

elemental analysis could not be obtained.

◦

(MeOH/CH₂Cl₂1 : 1) overnight at −30 C to yield 956 mg

(67 %) of [16][PF₆] as yellow needles. The crystalline ma-

terial contains one molecule of MeOH and half a molecule

of CH₂Cl₂per formula unit (analytical data, X-ray crystal

◦

structure analysis). – M. p. = 105 – 106 C. – [α]²_D³= +10.3

(–)-(1R)-1-Phenyl-2-[(3^ꢀ-methylbut-2^ꢀ-enyl)thio]ethylamine

(13)

(CH₂Cl₂, c = 0.00276). – ¹H NMR (CDCl₃, 400 MHz,

−30 ^◦C; contains CH₂Cl₂and MeOH; integration referenced

a) To 10 (1.180 g, 6.22 mmol) and t-BuOK (1.264 g, to methyl singlet of the η⁶-(p-cymene) ligand assigned to

11.26 mmol) in MeOH (35 mL) was added prenyl bromide the as diastereomer): δ = 7.90 – 7.88 (pseudo d, 2H, H_oof

Unauthenticated

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

137

Ph-S-, as), 7.78 – 7.76 (pseudo d, 0.64H, H_oof Ph-S-, aa), amount of warm CH₂Cl₂, layered at r. t. with MeOH and

◦

7.67 – 7.61 (m, 3H, H_m,pof Ph-S-, as), 7.50 – 7.42 (m, 0.96H, then with pentanes to be crystallized at −30 C overnight:

H_m,pof Ph-S-, aa), 7.34 (m, 7.92H, Ph-CH-, as and aa), 523 mg (80 %) of [17][PF₆], yellow microcrystals (X-ray

6.28 (br s, 2.64H, -NH₂-, as and aa), 6.06 – 6.0 (not res. d, crystal structure analysis). After crystallization [17][PF₆] is

3

0.32H, H – C(3 or 5) of η⁶-(p−cymene), aa), 5.98 (d, J = only sparingly soluble in CHCl₃or CH₂Cl₂, but moderately

5.8 Hz, 1H, H – C(3 or 5) of η⁶-(p−cymene), as), 5.89 (d, in acetone. – M. p. = 214 – 216 ^◦C. – [α]_D²³= +20.8 (CH₂Cl₂,

◦

³J = 5.8 Hz, 0.32H, H – C(5 or 3) of η⁶-(p−cymene), aa), c = 0.00284). – ¹H NMR (CDCl₃, 400 MHz, −30 C; in-

3

5.81 (d, J = 5.8 Hz, 1H, H – C(6 or 2) of η⁶-(p−cymene), tegration referenced to methyl singlet of the η⁶-mesitylene

as), 5.75 (d, ³J = 5.83 Hz, 0.32H, H – C(2 or 6) of η⁶- ligand assigned to the as diastereomer): δ = 7.96, 7.90, 7.82

(p−cymene), aa), 5.68 (d, ³J = 5.8 Hz, 0.32H, H – C(6 or 2) (3 pseudo d, 1.55H, H_oof Ph-S-), 7.68 – 7.30 (series of m,

of η⁶-(p−cymene), aa), 5.37 (d, ³J = 5.8 Hz, 1H, H – C(2 or 13.36H, Ph-S-, Ph-CH-), 5.49 (s, 3H, η⁶-mesitylene, as),

6) of η⁶-(p−cymene), as), 5.21 (d, ³J = 5.8 Hz, 1H, H – C(5 5.44 (s, 1.20H, η⁶-mesitylene, aa), 5.36 (br s, -NH₂-), 5.24

or 3) of η⁶-(p−cymene), as), 4.34 (m, 1H, -CH-, as), 3.91 (s, 0.30H, η⁶-mesitylene, sa), 5.19 (s, 0.21H, η⁶-mesitylene,

(m, 0.32H, -CH-, aa), 3.31 – 3.15 (3 partly res. dd, 1.64H, ss), 5.08 (br s, -NH₂-), 4.72 (m, 0.55H, -CH-), 4.42 (m,

-CH₂-, as and aa), 2.86 (h, ³J = 6.8 Hz, 0.32H, -CH(CH₃)₂, 0.29H, -CH-), 4.25 – 4.10 (2 m, 1.07H, -CH-), 3.69 (m,

2

3

aa), 2.67 (dd, J = 13.8, J = 4.2 Hz, 1H, -CH₂-, as), 2.54 0.73H, -CH₂-), 3.54 (m, 1.31H, -CH₂-), 3.35 (m, 0.80H,

(h, ³J = 6.8 Hz, 0.32H, -CH(CH₃)₂, as), 2.25 (s, 0.96H, -CH₂-), 3.12 (m, 1.07H, -CH₂-), 2.71 (dd, ²J = 13.8, ³J =

-CH₃, aa), 2.13 (s, 3H, -CH₃, as), 1.31 (d, ³J = 6.8 Hz, 3H, 3.8 Hz, 0.30H, -CH₂-), 2.25 (s, 9H, -CH₃, as), 2.02 (s,

-CH(CH₃)₂, as), 1.30 (d, ³J = 6.8 Hz, 0.96H, -CH(CH₃)₂, 3.60H, -CH₃, aa), 1.87 (s, 0.63H, -CH₃, ss), 1.70 (s, 0.90H,

aa), 1.22 (d, J = 6.8 Hz, 0.96H, -CH(CH₃)₂, aa), 1.18 (d, -CH₃, sa). – ¹³C{ H} NMR ([D₆]acetone, 75 MHz): δ =

3

1

³J = 6.8 Hz, 3H, -CH(CH₃)₂, as). – ¹³C{ H} NMR (CDCl₃, 139.18 (C_ipsoof Ph), 138.61 (C_ipsoof Ph), 134.05 (C_ipso

1

75 MHz): δ = 136.67 (C_ipsoof Ph-CH-, as and aa), 133.05 of Ph), 132.79 – 127.77 (Ph-S-, Ph-CH-), 105.86 (C_ipsoof

(C_oof Ph-S-, as), 132.47 (C_pof Ph-S-, as), 131.42 (C_oof η⁶-mesitylene), 104.93 (C_ipsoof η⁶-mesitylene), 82.52 (HC

Ph-S-, aa), 131.32 (C_mof Ph-S-, aa), 130.89 (C_mof Ph-S-, of η⁶-mesitylene), 81.77 (HC of η⁶-mesitylene); 81.45

as), 129.81 (C_mof Ph-CH-, aa), 129.60 (C_oof Ph-CH-, as (HC of η⁶-mesitylene), 62.17 (-CH-), 61.60 (-CH-), 60.15

and aa, C_mof Ph-CH-, as), 129.14 (C_pof Ph-S-, aa), 127.22 (-CH₃), 46.79 (-CH₂-), 43.56 (-CH₂-), 39.55 (-CH₂-), 18.71

(C_pof Ph-CH-, as), 126.96 (C_pof Ph-CH-, aa), 108.76 (C(4) (-CH₃). – FAB-MS: m/z (%) = 486 (100) [M – PF₆]⁺with

of η⁶-(p-cymene), aa), 106.13 (C(4) of η⁶-(p-cymene), as), respect to ¹⁰²Ru, 450 (23) [M – PF₆– Cl]⁺with respect to

+

101.68 (C(1) of η⁶-(p-cymene), as), 101.28 (C(1) of η⁶-(p- ¹⁰²Ru, 331 (27) [M – PF₆– Cl – C₉H₁₂

]

with respect to

cymene), aa), 87.84 (C(5 or 3) of η⁶-(p-cymene), as), 85.43 ¹⁰²Ru, 257 (24) [M – PF₆– Cl – C₉H₁₂– Ph]⁺with respect

(C(2 or 6) of η⁶-(p-cymene), as), 85.26 (C(5 or 3) of η⁶- to ¹⁰²Ru. – Anal. for C₂₃H₂₇ClF₆NPRuS (631.03): calcd.

(p-cymene), aa), 84.80 (C(3 or 5) of η⁶-(p-cymene), as), C 43.78, H 4.31, N 2.22, S 5.08; found C 43.84, H 4.59,

83.94 (C(6 or 2) of η⁶-(p-cymene), aa), 81.64 (C(6 or 2) N 2.21, S 5.03.

of η⁶-(p-cymene), as), 60.37 (-CH-, aa), 60.22 (-CH-, as),

[(–)-(1^ꢀR)-Chloro-η -[1,3,5-trimethylbenzene]-σ(N):σ(S)-

45.96 (-CH₂-, as), 43.54 (-CH₂-, aa), 31.18 (-CH(CH₃)₂,

6

[1^ꢀ-phenyl-2^ꢀ-(2^ꢀꢀ-naphthylthio)ethylamino]ruthenium(II)]

as), 30.98 (-CH(CH₃)₂, aa), 23.14 (-CH(CH₃)₂, as),

hexaﬂuorophosphate, [18][PF ]

22.30 (-CH(CH₃)₂, aa), 22.14 (-CH(CH₃)₂, as), 21.90

(-CH(CH₃)₂, aa), 18.42 (-CH₃, aa), 18.15 (-CH₃, as). –

FAB-MS: m/z (%) = 500 (100) [M − PF₆]⁺with re-

spect to ¹⁰²Ru, 464 (18) [M − PF₆− Cl]⁺with respect to

¹⁰²Ru. – Anal. for C₂₄H₂₉ClF₆NPRuS(CH₂Cl₂)_0.5(H₃COH)

(719.56): calcd. C 42.56, H 4.76, N 1.95, S 4.46; found

C 42.46, H 4.45, N 2.00, S 4.60.

6

According to the above procedure 15 (302 mg,

0.517 mmol) and 7 (313 mg, 1.120 mmol) were stirred for

13 h in MeOH (25 mL), and NaPF₆(392 mg, 2.334 mmol)

was added then. The soln. was stirred for 30 h, worked up

as described above and crystallized from CH₂Cl₂layered

with some drops of MeOH at −30 ^◦C to afford 582 mg

(83 %) of [18][PF₆] as yellow microcrystals (X-ray crys-

tal structure analysis). Solubility of crystalline [18][PF₆]:

acetone = MeCN > CH₂Cl₂≥ THF ꢁ MeOH. – M. p. =

221 – 222 ^◦C. – [α]_D²³= −8.6 (CH₂Cl₂, c = 0.00266). –

6

[(+)-(1^ꢀR)-Chloro-η -[1,3,5-trimethylbenzene]-σ(N):σ(S)-

[1^ꢀ-phenyl-2^ꢀ-(phenylthio)ethylamino]ruthenium(II)]

hexaﬂuorophosphate, [17][PF ]

6

According to the above procedure, 15 (301 mg, ¹H NMR ([D₆]acetone, 300 MHz, integration referenced to

(0.515 mmol) and 5 (254 mg, 1.107 mmol) were stirred for η⁶-mesitylene singlets assigned to the aa diastereomer): δ =

13 h in MeOH (25 mL), and NaPF₆(387 mg, 2.304 mmol) 8.65 – 7.42 (series of m, 80.63H, β-Naph, Ph), 6.38 (br s,

was added then. The soln. was stirred for 30 h and worked up -NH₂-), 6.07 (not res. dd, 0.83H, -CH-), 5.81 (s, 2.92H,

as described above to afford 688 mg crude product as a solid η⁶-mesitylene, as), 5.71 (s, 3H, η⁶-mesitylene, aa), 5.48

yellow foam. The crude product was dissolved in a minimum (2 br not res. s, 2.72H, η⁶-mesitylene, sa and ss), 5.34

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138

I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

(br s, -NH₂-), 4.64 (not res. dd, 0.53H, -CH-), 4.33 – 3.82 (C_ipsoof η⁶-mesitylene, sa), 80.35 (HC of η⁶-mesitylene,

(2 not res. dd, 3.39H, -CH-, -CH₂-), 3.75 (dd, ²J = 32.9, aa), 62.61 (-CH-), 60.78 (-CH-), 59.76 (-CH₃, ss), 40.46

³J = 12.4 Hz, 2.10H, -CH₂-), 3.46 – 2.90 (series of m, 5.2H, (-CH₂-CH=C(CH₃)₂, as + aa or sa + ss), 38.13 (-CH₂–

-CH-, -CH₂-), 2.37 (s, 8.78H, -CH₃, as), 2.36 (s, 9H, - CH=C(CH₃)₂, sa + ss or as + aa), 36.86 (-CH₂-), 35.46

CH₃, aa), 2.18 (2 not res. s, 8.16H, -CH₃, sa and aa). – (-CH₂-), 31.79 (-CH₂-), 31.22 (-CH₃, sa), 25.90 (-CH₂-

1

¹³C{ H} NMR ([D₆]acetone, 75 MHz): δ = 138.71 (C_ipsoCH=C(CH_3cis)(CH₃)), 18.51 (-CH₂-CH=C(CH₃)(CH_3trans),

of Ph or C(2) of β-Naph), 138.17 (C_ipsoof Ph or C(2) -CH₃, as + aa). – FAB-MS: m/z (%) = 479 (100) [M –

of β-Naph), 134.34 – 126.26 (β-Naph, Ph), 105.33 (C_ipsoPF₆]⁺with respect to ¹⁰²Ru, 374 (38) [M – PF₆– Cl

of η⁶-mesitylene), 104.28 (C_ipsoof η⁶-mesitylene), 82.27 – Prn]⁺with respect to ¹⁰²Ru, 254 (22) [M – PF₆– Cl

(HC of η⁶-mesitylene), 81.45 (HC of η⁶-mesitylene), 81.13 – Prn – mesitylene]⁺with respect to ¹⁰²Ru. – Anal. for

(HC of η⁶-mesitylene), 61.72 (-CH-), 61.06 (-CH-), 59.58 C₂₂H₃₁ClF₆NPRuS (CH₂Cl₂)_0.5(665.51): calcd. C 40.61,

(-CH-), 50.20 (-CH₂-), 46.64 (-CH₂-), 43.11 (-CH₂-), 38.82 H 4.85, N 2.10, S 4.82; found C 40.59, H 4.88, N 2.08,

(-CH₂-), 31.98 (-CH₃), 31.47 (-CH₃), 20.15 (-CH₃). – FAB- S 4.81.

MS: m/z (%) = 537 (100) [M – PF₆]⁺with respect to ¹⁰²Ru,

501 (70) [M – PF₆– Cl]⁺with respect to ¹⁰²Ru. – Anal.

for C₂₇H₃₀ClF₆NPRuS (682.09): calcd. C 47.54, H 4.43,

N 2.05, S 4.70; found C 47.24, H 4.54, N 2.01, S 4.66.

Crystal structure determinations

Crystal parameters, data collection and structure reﬁne-

ment details are summarized in Table 11. Intensity data

were collected at 100 K on a Bruker-Nonius KappaCCD

6

[(+)-(1^ꢀR)-Chloro-η -[1,3,5-trimethylbenzene]-σ(N):σ(S)-

˚

diffractometer (MoK_αradiation, λ = 0.71073 A, graphite

[1^ꢀ-phenyl-2^ꢀ-(3^ꢀꢀ-methylbut-2^ꢀꢀ-enylthio)ethylamino]

monochromator). Absorption corrections were performed

using either a numerical Gauss integration [11a] or on the ba-

sis of multiple scans with SADABS [11b]. All structures were

solved with Direct Methods and reﬁned by full-matrix least-

squares procedures on F²[12]. The absolute conﬁgurations

were conﬁrmed, respectively determined, by anomalous dis-

persion effects by means of Flack’s x reﬁnement [13]. All

non-hydrogen atoms were reﬁned with anisotropic displace-

ment parameters. All H-atoms were placed in positions of

optimized geometry; their isotropic displacement parameters

were tied to the equivalent isotropic displacement parame-

ters of their corresponding carrier atoms by a factor of 1.2

or 1.5, respectively. The CH₂Cl₂solvent molecule in the

crystal structure of [16][PF₆] is situated on a crystallographic

twofold axis. High anisotropic displacement parameters for

some carbon atoms in the crystal structure of [17][PF₆] in-

dicate a possible disorder. However, attempts to resolve this

disorder remained unsuccessful. Similarity restraints (SIMU)

were applied in the reﬁnement of some of the carbon atoms

in the crystal structure of [18][PF₆]. The PF⁻₆anions in the

crystal structure of [19][PF₆] are located on crystallographic

twofold axes. The CH₂Cl₂solvent molecule in [19][PF₆] is

disordered.

ruthenium(II)] hexaﬂuorophosphate, [19][PF ]

6

According to the above procedure 15 (411 mg,

0.703 mmol) and 13 (332 mg, 1.500 mmol) were stirred for

15 min in MeOH (6 mL), and NaPF₆(361 mg, 2.149 mmol)

was added then. The soln. was stirred for 16 h, worked up as

described above and crystallized from a minimum amount of

warm MeOH with_◦some drops of CH₂Cl₂by cooling from

r. t. down to −30 C overnight to afford 726 mg (78 %) of

[19][PF₆]. The compound crystallizes with half a molecule

of CH₂Cl₂per formula unit (analytical data, X-ray struc-

ture analysis). – M. p. = 133 – 134 ^◦C. – [α]_D²³= +17.6

1

(CH₂Cl₂, c = 0.0017). – H NMR (CDCl₃, 300 MHz, inte-

gration referenced to η⁶-mesitylene singlets assigned to the

aa diastereomer): δ = 7.48 – 7.30 (m, 11.07H, Ph), 5.40 (s,

2.44H, η⁶-mesitylene, as), 5.36 (s, 3H, η⁶-mesitylene, aa),

5.28 (2 broadened s, 1.83H, η⁶-mesitylene, sa and ss), 5.27 –

5.19 (3 m, 1.93H, -CH=C(CH₃)₂), 5.16 – 4.96 (m, 1.93H,

-CH-), 4.14 – 4.00 (m, 1.42H, -CH-), 3.78 – 3.34 (series of

m, 8.70H, -CH-, -CH₂-), 3.08 (dd, ²J = ³J = 13.6 Hz, 1.17H,

-CH₂–CH=C(CH₃)₂, as + aa or sa + ss), 2.83 (m, 0.92H,

-CH₂–CH=C(CH₃)₂, sa + ss or as + aa), 2.67 (dd, ²J =

13.7, ³J = 11.3 Hz, 1.00H, -CH₂–CH=C(CH₃)₂, sa + ss

or as + aa), 2.46 – 2.42 (m, 1.15H, -CH₂–CH=C(CH₃)₂, as

+ aa or sa + ss), 2.20 (s, 7.32H, -CH₃, as), 2.19 (s, 9H,

CCDC 669750 (9), CCDC 669751 ([16][PF₆]·(CH₂-

Cl₂)_0.5·(MeOH)), CCDC 669752 ([17][PF₆]), CCDC

669753 ([18][PF₆]) and CCDC 669754 ([18][PF₆]·(CH₂-

Cl₂)_0.5) contain the supplementary crystallographic data

for this paper. These data can be obtained free of charge

from the Cambridge Crystallographic Data Centre via http://

www.ccdc.cam.ac.uk/data request/cif.

4

-CH₃, aa), 1.81 and 1.75 (2 partly res. d, J_cis= 10.2 and

⁴J_trans= 16.1 Hz, 11.81H, -CH₂–CH=C(CH₃)₂, all diastere-

omers), 1.39 (s, 0.48H, -CH₃, ss), 1.09 (s, 1.36H, -CH₃,

1

sa). – ¹³C{ H} NMR (CDCl₃, 75 MHz): δ = 141.77 (C_ipso

of Ph), 141.65 (C_ipsoof Ph), 137.68 (C_ipsoof Ph), 136.37

(-CH=C(CH₃)₂), 129.63 (C_pof Ph), 129.54 (C_mof Ph),

129.43 (C_pof Ph), 127.16 (C_oof Ph), 126.89 (C_oof Ph),

115.82 (-CH=C(CH₃)₂), 115.76 (-CH=C(CH₃)₂), 105.21

Acknowledgements

We are grateful to the Deutsche Forschungsgemein-

(HC of η⁶-mesitylene), 103.77 (HC of η⁶-mesitylene), 81.07 schaft (SFB 583) for ﬁnancial support and to the fol-

Unauthenticated

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I. Weber et al. · β-Aminothioether-chelated Ru(II) η⁶-Arene Complex Salts

139

lowing colleagues of the Department Chemie & Phar- ciplinary Center for Molecular Materials (ICMM)) for

mazie, Friedrich-Alexander-Universita¨t Erlangen-Nu¨rnberg: providing access to essential analytical equipment, and

Prof. Dr. Peter Gmeiner (Emil Fischer Center) and Prof. Dr. Wolfgang Utz (Emil Fischer Center) for helpful

Dr. Andreas Hirsch (Organic Chemistry and Interdis- discussions.

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Configurational flexibility of epimeric β-aminothioether-chelated ruthenium(II) η6-arene complex salts

DOI: 10.1515/znb-2009-0117

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