Ruthenium Complexes of Stibino Derivatives of Carboxylic Amides: Synthesis and Characterization of Bidentate Sb,E, Tridentate Sb,E2, and Tetradentate Sb,E3 (E = N and O) Ligands and Their Reactivity Toward [RuCl2(PPh3)3]

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Ruthenium Complexes of Stibino Derivatives of Carboxylic Amides:

Synthesis and Characterization of Bidentate Sb,E, Tridentate Sb,E₂,

and Tetradentate Sb,E₃(E = N and O) Ligands and Their Reactivity

Toward [RuCl₂(PPh₃)₃]

̈

Robert Gericke* and Jorg Wagler*

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Supporting Information

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ABSTRACT: Neutral bi-, tri-, and tetradentate ligands of the type

Ph_3−xSb(L)_x[x = 1 (1), 2 (2), and 3 (3). L = La = phthalimidinyl (1a,

2a, and 3a), Lb = 2-pyridyloxy (1b, 2b, and 3b)] have been synthesized and

characterized. Reaction of the Sb,E and Sb,E₂ligands with [RuCl₂(PPh₃)₃]

proceeded under anion scrambling with formation of complexes of type

[Ph₂Sb(μ-L)₂Ru(PPh₃)(μ-Cl)]₂(5) or [PhSb(μ-L)₃RuCl(PPh₃)] (8) in

addition to various byproducts. Reactions of the Sb,E₃ligands and

[RuCl₂(PPh₃)₃] aﬀorded highly diverse product mixtures. Deliberate

syntheses of complexes of types 5 and 8 were successful by supplementing

the reaction mixture with the required stoichiometric amount of either HLa

or HLb and a supporting base. The Sb−Ru bonds, which are bridged by two

(type 5) or three (type 8) phthalimidinyl or 2-pyridyloxy ligands, have been

investigated using quantum chemical calculations at the DFT level (NBO/

NLMO and AIM). Treatment of complexes of type 8 with ﬂuoride ions

resulted in the formation of compounds of type [PhFSb(μ-La)₃RuL′(PPh₃)] (L′ = O₂(9a-O₂), NCMe (9a-NCMe), or [PhFSb(μ-

Lb)₂Ru(κ²-Lb)(PPh₃)] (10b)). In contrast to other similar bimetallic Sb-TM complexes (TM = transition metal), which may switch

the rather dative intermetallic bond from Sb→TM to Sb←TM upon replacing TM bound chloride by Sb-bound ﬂuoride, the

character of the Sb→Ru bond is essentially retained upon going from chloro complex 5 or 8 to ﬂuoro complex 9 or 10. Charge

discrepancies caused by anion transfer from Ru to Sb are mainly compensated for by charge ﬂow along the ligand backbone. All

isolated complexes were characterized with multinuclear NMR spectroscopy, single-crystal X-ray diﬀraction, elemental analysis, and

quantum chemical calculations.

bimetallic complexes. For some known literature cases, which

have not been analyzed with respect to the M′−TM bond

characteristics, we consider Z-type ligand characteristics of M′

(Chart 2). For example, Oro et al. reported several complexes

with Ir−Si and Rh−Si core featuring 2-pyridyloxy as (N,O)-

bridging ligands, which exhibit catalytic activity toward

hydrosilylation of CO₂. In the original papers, the authors

interpreted the complexes as silyl complexes of Ir(III) and

Rh(III), which implies the presence of an Si-located σ-electron

pair in the TM coordination sphere.⁶However, a reinterpreta-

tion of the assigned oxidation state to Ir(I)→Si(IV) and

Rh(I)→Si(IV) is validated by the fact that both transition metals

INTRODUCTION

■

The covalent σ-bond characteristics in various heterobimetallic

complexes featuring an M′−TM core (M′ = main group metal/

metalloid, TM = transition metal) are of current interest. The

nature of σ-bonds has been classiﬁed by Green according to the

L/X/Z-formalism,¹and with respect to M′ as a ligand atom in

the coordination sphere of TM, this classiﬁcation implies the

following σ-bond electron pair allocation: L: M′→TM (A); X:

M′−TM (B and D); Z: M′←TM (C, E, and F); Chart 1).^2,3

Ambidentate (C,P)- and (N,S)-donor ligands are known for

their ability to stabilize various heterobimetallic cores and

possibly support changes between the three mentioned bonding

modes by shifting the σ-bond electron pair from essentially M′-

located via almost equally shared between M′ and TM to almost

TM-located.

Received: February 13, 2020

Complexes featuring an Au(I)→Sb(V)⁴or Pt(I)−Sb(IV)⁵

bond are examples of successful incorporation of a so-called

noninnocent main group metal ligand in a TM complex. (N,O)-

bridging ligands, e.g., 2-pyridyloxy, may also stabilize hetero-

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a

Chart 1. Examples of Hetero-Bimetallic Complexes Containing an M′−TM Bond Bridged by (C,P) or (N,S) Ligands

a

M′ = heavy main group metal, TM = transition metal. The red arrows or lines emphasize the polarization of this bond and the formal direction of

the resulting donation. For clarity, this expression was limited to the M′−TM bond; therefore, formal charges have not been assigned.

a

Chart 2. Examples of Hetero-Bimetallic Complexes Containing an M′−TM Bond Bridged by (N,O) Ligands

a

M′ = main group metal/metalloid, TM = transition metal. The red arrows emphasize the polarization of this bond and the formal direction of the

resulting donation. For clarity, this expression was limited to the M′−TM bond, and therefore formal charges have not been assigned.

a

Scheme 1. Synthesis of Ph_3−xSb(NEt₂)_x(x = 1, 2, and 3)

a

LiNEt₂was prepared in situ from nBuLi and Et₂NH.

B

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exhibit higher electronegativity than that of Si (Pauling scale; see

the Supporting Information for further details).⁷An analogous

reinterpretation of the bond characteristics in complex H

reported by Deng et al. indicated contributions of the two

canonical forms Co(I)→Si(IV) (Z-type) and Co(II)−Si(III)

(X-type) to the Co−Si bond in this compound, as there is only a

rather weak shift of the σ-bond electron pair belonging toward

cobalt (NLMO: Co: 54.7%, Si: 43.0%).⁸Hence, this complex is

by far no silylene complex, as silylene would require a

predominantly Si-located electron pair. A situation similar to

that in H was found for Rh−Sb complex D.^3aBerry et al.

reported a Rh−Bi complex featuring four bridging 6-

chloropyridyl-2-oxy ligands (I), and because of the Rh−Bi

core with Rh−Bi bond and four anionic bridges, the oxidation

states Rh(II) and Bi(II) were assigned.⁹The electronegativity of

Rh is higher than that of Bi and thus indicates a possible Rh(I)→

Bi(III) bonding (see the Supporting Information for detail).

As transition metals of group 9 (Co, Rh, and Ir) were shown

capable of acting as formal electron pair donor toward metalloid

main group elements (Si and Bi) and ambidentate (N,O)-

bridging ligands such as 2-pyridyloxy may stabilize the

heterobimetallic cores, we aimed at combining the catalytically

versatile group 8 element Ru with Sb as the main group

metalloid. Whereas the former was already successfully utilized

for syntheses of metallaboratranes (featuring Ru→B bonds),¹⁰

the latter was shown capable of switching the TM−Sb bond

directionality upon redox reaction or ligand exchange. For the

current study, we have chosen the known 2-pyridyloxy ligand

and the more uncommon phthalimidinyl ligand in comparison

to stabilize the Ru−Sb cores and their inherent intermetallic σ-

bonds.

temperature (1a, 1b, 3a, and 3b) or after additional vapor

diﬀusion of Et₂O into the THF solution (2a and 2b).

Scheme 2. Synthesis of Ph_3−xSb(L)_x(x = 1, 2, and 3; L = La,

Lb; 1a−3b)

In general, both phthalimidinyl and 2-pyridyloxy groups may

bind to Sb via the N or O atom. For the analogous phosphorus

derivatives, we found systematic P−N bonding for the

phthalimidinyl and P−O bonding for the 2-pyridyloxy

derivatives (see Supporting Information).¹¹The ¹H NMR

spectra of 1a−3b are similar to those of their lighter phosphorus

homologues, which had already been reported. 2-Pyridyloxy

derivatives 1b, 2b, and 3b clearly show a systematic high-ﬁeld

shift of the PyO related signals relative to the corresponding

compounds Ph₂P(Lb), PhP(Lb)₂, and P(Lb)₃, respectively.

Also, the signals for compounds 1b, 2b, and 3b are noticeably

broadened, indicating dynamic exchange of the ambidentate

(N,O) ligand. Phthalimidinyl derivatives 1a, 2a, and 3a show

changes of the phthalimidinyl-related signals in the aromatic

area in a very narrow range with respect the corresponding

signals of compounds Ph₂P(La), PhP(La)₂, and P(La)₃,

respectively, whereas the signals for the CH₂group are

systematically high-ﬁeld-shifted in the case of the antimony

homologues by about 0.2−0.6 ppm. We attribute these high-

ﬁeld shifts of the ¹H NMR signals for compounds 1a−3b relative

to those of their phosphorus analogues to the more pronounced

ionic Sb−N/Sb−O bonding situation (relative to P−N/P−O)

and the resulting more electron-rich (more anionic) substituents

(see the Supporting Information for further details). The signal

broadening observed with the Sb-PyO compounds, however,

hints at noticeable diﬀerences between Sb and P analogous

compounds. To conﬁrm this hypothesis, we used quantum

chemical calculations to analyze the relative energies of the sets

of Pn−N and Pn−O bonded isomers (Pn = P and Sb) for all

compounds under investigation (Table 1, Chart 3).

These quantum chemical calculations of the gas-phase-

optimized structures have shown that for phthalimidinyl

derivatives the isomers exclusively featuring P−N and Sb−N

bonding are the thermodynamically favored isomers. Further-

more, for the 2-pyridyloxy derivatives the P−O bonding

situation is thermodynamically more favorable than the P−N

bonding mode in compounds of types 1, 2, and 3. In the case of

Pn = Sb (compound 1b), the energy diﬀerences between

isomers 1b^Iand 1b^IIis very small, thus indicating coexistence of

both isomers in equilibrium. This is in good agreement with the

large high-ﬁeld shift of the H⁶signal in the ¹H NMR spectrum by

about 0.6 ppm with respect to the analogous P-compound (in

1b^I, H⁶is located above the shielding cone of the plane of a

phenyl ring, leading to a pronounced shielding). Hence, the

single set of rather broad ¹H NMR signals observed for

compound 1b is most likely caused by rapid exchange between

both isomers 1b^Iand 1b^IIin solution. For compounds 2b and

3b, the energy diﬀerence between isomers 2^IIand 2^IIIas well as

RESULTS AND DISCUSSION

■

Compounds of the type Ph_3−xSb(L)_x. Compounds of this

type may be synthesized from chlorostibines and carboxylic

amides along base-supported routes. The reactivity patterns of

group 15 element chlorides toward carboxylic amides¹¹have

already been investigated. However, as antimony is a rather

chlorophilic element, e.g., formation of SbCl₄⁻salts, we aimed at

syntheses with chlorine-free starting materials; therefore, we

converted all chlorostibine starting materials into the respective

N,N-diethylamino derivatives prior to further conversions

(Scheme 1). For compounds with x = 3 we utilized

commercially available SbCl₃as starting material. Owing to

the very limited availability of both Ph₂SbCl and PhSbCl₂and

their rather facile formation upon heating SbCl₃and SbPh₃, we

prepared these compounds in situ by direct heating of Ph₃Sb and

SbCl₃in 2:1 and 1:2 molar ratios, respectively.¹²In both cases,

the desired phenylchlorostibine exhibited impurities of various

compounds of the composition Ph_3−xSbCl_x(x = 0−2; detected

by ¹³C NMR spectroscopy). As these impurities may form again

during distillation (by substituent redistribution at higher

temperatures), we converted these compounds into their N,N-

diethylamino derivatives prior to puriﬁcation by distillation. In

all cases, the N,N-diethylaminostibine could be separated by

fractional distillation, while the byproduct LiCl remained in the

still and partly in the condenser.¹³In a clean manner, the

reactions of Ph_3−xSb(NEt₂)_x(x = 1, 2, and 3) with phthalimidine

(HLa) or 2-hydroxypyridine (HLb) in hot THF aﬀorded

compounds Ph_3−xSb(L)_x(x = 1, L = La: 1a, L = Lb: 1b; x = 2, L

= La: 2a, L = Lb: 2b; x = 2, L = La: 3a, L = Lb: 3b; Scheme 2),

which crystallized after the solution was allowed to attain room

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Table 1. Energy Diﬀerence (ΔE, kcal mol⁻¹) between the Isomers of Compounds of the Type Ph₂Pn(L) (1), PhPn(L)₂(2), and

a

Pn(L)₃(Pn = P and Sb; L = La and Lb)

Pn

L

1^I

1^II

2^I

2^II

2^III

3^I

3^II

3^III

3^IV

P

Sb

P

0.00

2.38

0.41

10.87

6.57

0.00

6.59

6.09

21.79

7.31

1.34

0.00

11.16

2.25

0.00

1.94

0.00

11.82

8.33

7.37

9.36

0.16

16.16

12.49

4.58

25.95

19.20

0.00

La

Lb

Sb

3.33

0.00

1.74

a

Energy values of the crystallographically characterized isomers are written in italic and bold text.¹¹

Chart 3. Possible Isomers of Compounds of Type Ph₂Pn(L) (1), PhPn(L)₂(2), and Pn(L)₃(Pn = P and Sb; L = La and Lb)

those for 3^II, 3^III, and 3^IVare small. Both isomers 2^Iand 3^Iwith

exclusive Sb−N bonding situations are less favored. Therefore,

in solution both compounds are likely to exhibit Sb−O and Sb−

N bonding modes (again in rapid exchange between the

isomers), which is in good agreement with the signal broadening

observed in their ¹H NMR spectra.

For 2a, 2b, 3a, and 3b, we obtained crystals suitable for single-

crystal X-ray diﬀraction (Figures 1 and 2). The molecular

structures represent the isomers with Sb−N bonds in 2a and 3a

Figure 2. Molecular structures of 3a (left) and 3b (right). Ellipsoids are

and Sb−O in 2b and 3b. In the structures of 2a and 3a, the

shown at 50% probability level. Hydrogen atoms have been omitted for

clarity. Selected interatomic separations (Å) and angles (deg): 3a:

antimony coordination spheres reveal rather long Sb1···O

Sb1−N1 2.056(3), Sb1−N2 2.071(3), Sb1−N3 2.074(3), C1−N1

1.349(5), C1−O1 1.242(5), C9−N2 1.366(5), C9−O2 1.234(5),

C17−N3 1.363(5), C17−O3 1.241(4), N1−Sb1−N2 89.62(12), N1−

Sb1−N3 91.54(12), N2−Sb1−N3 90.84(12), O1−C1−N1 122.3(4),

O2−C9−N2 124.8(3), O3−C17−N3 123.7(3). 3b: Sb1−O1

2.103(1), Sb1−O2 2.087(1), Sb1−O3 2.026(1), C1−N1 1.337(2),

C1−O1 1.330(2), C6−N2 1.340(2), C6−O2 1.330(2), C11−N3

1.336(2), C11−O3 1.337(2), O1−Sb1−O2 80.51(4), O1−Sb1−O3

87.98(4), O2−Sb1−O3 87.98(4), O1−C1−N1 113.49(12), O2−C6−

N2 114.99(12), O3−C11−N3 115.82(12).

Figure 1. Molecular structures of 2a (left) and 2b (right). Ellipsoids are

shown at 50% probability level. Hydrogen atoms have been omitted for

clarity. Selected interatomic separations (Å) and angles (deg): 2a:

Sb1−N1 2.063(3), Sb1−N2 2.110(3), Sb1−C17 2.142(3), C1−N1

1.365(4), C1−O1 1.217(4), C9−N2 1.342(4), C9−O2 1.246(4), N1−

Sb1−N2 89.23(11), N1−Sb1−C17 95.50(12), N2−Sb1−C17

91.61(11), O1−C1−N1 123.3(3), O2−C9−N2 123.4(3). 2b: Sb1−

O1 2.078(1), Sb1−O2 2.057(1), Sb1−C11 2.142(2), C1−N1

1.336(3), C1−O1 1.332(2), C6−N2 1.328(2), C6−O2 1.335(2),

O1−Sb1−O2 78.70(5), O1−Sb1−C11 94.95(6), O2−Sb1−C11

95.57(6), O1−C1−N1 114.15(15), O2−C6−N2 115.91(16).

separations (2a: 3.038(3), 3.069(3) Å; 3a: 2.910(3), 3.073(3),

3.174(3) Å)), indicating weak attractive interactions, which was

conﬁrmed by computational methods: The noncovalent

interaction descriptor (NCI) reveals very weak attractive

interactions, close to van der Waals interactions (Supporting

Information). In contrast, in compounds 2b and 3b the Sb1···N

separations are quite short (2b: 2.534(2), 2.719(2) Å; 3b:

2.453(1), 2.740(1), 2.594(1) Å), and the O−Sb−O angles are

signiﬁcantly smaller than 90°. For the additional donor−

acceptor interactions in these compounds (2b and 3b), the NCI

D

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Scheme 3. Synthesis of Complexes of Type 4 and 5

shows pronounced attractive interactions, and their antimony

coordination spheres may thus be described as 2- or 3-fold

capped pyramidal, respectively.

Reactivity of Ph_3−xSb(L)_xtoward [RuCl₂(PPh₃)₃]. Aiming

at the formation of compounds with (N,O)-supported Sb−Ru

bonds, we investigated the reactivity of the bi- and tridentate

Sb,O- and Sb,N-donor ligands 1a−2b toward the 16e⁻complex

[RuCl₂(PPh₃)₃]. As reported for the phosphorus analogs of

these ligands, Ru complexes with mono- or dibridged P−Ru

bonds are formed with the phosphorus atom in a distorted

tetrahedral coordination sphere. The combination of heavier

stibino analogs 1a and 1b with [RuCl₂(PPh₃)₃] exhibit diﬀerent

reaction patterns under similar conditions (Scheme 3). In both

cases, the reaction with [RuCl₂(PPh₃)₃] in a 1:1 molar ratio

leads to the formation of a mixture of [Ph₂ClSb(μ-L)Ru(PPh₃)-

(μ-Cl)₃Ru(PPh₃)₂SbClPh₂] (L = La: 4a; L = Lb: 4b),

[Ph₂Sb(μ-L)₂Ru(PPh₃)(μ-Cl)]₂(L = La: 5a; L = Lb: 5b),

and yet unidentiﬁed byproducts. The ³¹P NMR spectra of the

crude reaction mixture of 1a with [RuCl₂(PPh₃)₃] show

multiple signals in the range 37−63 ppm, which correspond to

the presence of several complexes. A clear assignment was not

possible. The ³¹P NMR spectra of the crude reaction mixture of

1b with [RuCl₂(PPh₃)₃] show the following pattern next to the

characteristic signal of PPh₃: 57.6 (s), 52.8 (s), 51.4 (s), 49.1 (br.

s), 45.1 (d, J = 31.7 Hz), 44.8 (d, J = 30.3 Hz), 43.9 (d, J = 31.7

Hz), 43.7 (d, J = 31.0 Hz), 42.7 (d, J = 31.1 Hz), 39.8 (d, J = 30.2

Hz) ppm. The signals at 49.1, 45.1, and 43.9 ppm appear in the

ratio 1:1:1 and increase in intensity simultaneously. Therefore,

an assignment of these signals to complex 4b is obvious. The

signal at 52.8 ppm also increases in intensity over time and was

assigned to 5b (vide infra). All other signals could not be

assigned to well-deﬁned products.

Both reactions proceeded with liberation of PPh₃and with

(N,O) ligand versus Cl⁻exchange. The compounds of type 4

arise from formal loss of 1 equiv of L⁻and addition of 1 equiv of

Cl⁻with respect to the expected formula [Ph₂Sb(μ-L)-

RuCl₂(PPh₃)₂]. Accordingly, the compounds of type 5 are

formed by uptake of 2 equiv of L⁻and loss of 2 equiv of Cl⁻.

Attempts to isolate pure 4 or 5 via fractional crystallization

failed. Upon crystal picking from the crystalline product

mixtures, it was possible to determine the molecular structures

of 4a and 4b with single-crystal X-ray diﬀraction (Figure 3, Table

2).

Figure 3. Molecular structures of 4a·1.38CHCl₃(top) and 4b·2Et₂O

(bottom). Ellipsoids are shown at 50% probability level. Hydrogen

atoms and solvent molecules have been omitted for clarity.

E

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Table 2. Selected Interatomic Separations (Å) and Angles (deg) in 4a·1.38CHCl₃and 4b·2Et₂O

4a

4b

4a

4b

Ru1−Sb1

Ru2−Sb2

Ru1−Cl1

Ru1−Cl2

Ru1−Cl3

Ru2−Cl1

Ru2−Cl2

Ru2−Cl3

Ru1−P1

2.547(1)

2.476(2)

2.414(2)

2.459(2)

2.433(3)

2.462(2)

2.504(2)

2.271(2)

2.337(3)

100.8(3)

97.2(3)

2.549(1)

2.532(1)

2.470(1)

2.446(1)

2.489(1)

2.452(1)

2.421(1)

2.488(1)

2.285(1)

2.361(7)

99.8(2)

Ru2−P3

Ru1−N1

Sb1−C

2.335(2)

2.033(7)

2.142(9)

2.144(9)

2.147(8)

2.148(9)

2.546(2)

2.369(2)

2.230(6)

2.321(1)

2.089(3)

2.140(5)

2.153(4)

2.125(5)

2.132(5)

2.553(1)

2.369(1)

2.151(3)

Sb2−C

Sb1−Cl4

Sb2−Cl5

Sb1−O

Ru2−P2

C−Sb1−C

C−Sb2−C

Cl4−Sb1−O1

Sb1−Ru1−Cl3

Sb2−Ru2−Cl_trans

167.7(1)

155.8(1)

165.9(1)

158.1(1)

101.0(2)

171.5(1)

168.4(2)

The coordination spheres of the two ruthenium atoms in 4a

and 4b are distorted octahedral. The chlorine atoms Cl1−Cl3

adopt a bridging mode between both ruthenium atoms. Such a

Ru(μ-Cl)₃Ru motif has already been reported by Lavigne et al. in

the molecular structure of [Ph₂P(2,6-lutidinyl)(Ph₃P)Ru(μ-

Cl)₃Ru(PPh₃)₂Cl], which interestingly is formed by a similar

reaction of a bidentate (P,N)-ligand with [RuCl₂(PPh₃)₃].¹⁴

The Ru−Cl bond lengths span the range of 2.41−2.50 Å and are

therefore in good agreement with the Ru−Cl bonds reported by

Lavigne et al. Coordination about the Sb1 atoms is distorted

trigonal bipyramidal, whereas the Sb2 atoms exhibit a distorted

tetrahedral coordination sphere. The Ph₂SbCl(L) unit (L = La

and Lb) may be interpreted as formal mono anionic ligand, and

the Ph₂SbCl unit may be interpreted as a neutral ligand at the

(Ru₂Cl₃)⁺core. Leong et al. and Rat

̧ et al. reported the

coordination behavior of Ph₂SbCl toward osmium and

tungsten.^15,16Compounds 4a and 4b are the ﬁrst examples of

crystallographically characterized compounds with a Ph₂ClSb−

Ru motif.¹⁷In spite of diﬀerent (N,O)-bridging ligands, the

Sb1−Ru1 bond lengths in 4a and 4b are very similar, whereas

the Sb2−Ru2 bond lengths diﬀer by about 0.02 Å.

From the products of the reactions of 1a or 1b with

[RuCl₂(PPh₃)₃] in an 1:1 ratio, it is evident that the antimony

atom tends to achieve a higher coordination number, a behavior

which has not been observed for reactions with the phosphorus-

analogous compounds.¹¹For further investigation, compounds

5a and 5b were synthesized in a deliberate manner by addition of

1 equiv of HLa or HLb and a supporting base (Et₃N) to the

reaction mixture. As for complexes of both types 4 and 5, ligand

systems La and Lb exclusively adopt the Sb−O,Ru−N bridging

mode, and the Sb−N bond in starting material 1a needs to be

cleaved in the course of the formation of 5a. Complexes 5a and

5b exhibit moderate solubility in organic solvents, thus allowing

for NMR spectroscopic characterization in solution. The ³¹P

NMR spectra (CD₂Cl₂solution) feature a singlet signal at 51.6

(5a) and 52.8 ppm (5b) for the Ru-bound PPh₃ligand. These

shifts are similar to those observed with complexes of the type

[PhP(μ-L)₂RuCl₂(PPh₃)] (L = La, ³¹P: 57.0 (CD₂Cl₂); Lb, ³¹P:

41.0 (CDCl₃)).¹¹The molecular structures of 5a and 5b were

determined with single-crystal X-ray diﬀraction (Figure 4, Table

3).

Figure 4. Molecular structures of 5a·2Et₂O·THF (top) and 5b·CHCl₃·

Et₂O (bottom). Ellipsoids are shown at the 50% probability level.

Hydrogen atoms and solvent molecules have been omitted for clarity.

featuring a central Ru(μ-Cl)₂Ru motif. Interestingly, the Ru1−

Cl1 bond trans to the Sb1−Ru1 bond is signiﬁcantly shorter (by

about 0.03 Å) than the corresponding cis located bond Ru1−

Cl1*. Due to the bridging coordination mode of the Cl atoms,

the Sb1−Ru1−Cl1 angle is signiﬁcantly bent out of linearity by

about 20°. Despite liberation of PPh₃during the reaction and

In the crystal structures, the centers of gravity of both

complexes 5a and 5b are located on a crystallographic center of

inversion. Thus, the asymmetric unit is expressed by one-half

molecule. In analogy to complexes of type 4, the ruthenium

atoms in 5a and 5b are distorted octahedrally coordinated,

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Table 3. Selected Interatomic Separations (Å) and Angles (deg) in 5a·2Et₂O·THF, 5b·CHCl₃·Et₂O, and 6a·2.5Et₂O

5a

5b

6a

5a

5b

6a

Ru1−Sb1

Ru1−Cl1

Ru1−P1

Ru1−N1

Ru1−N2

Ru1−Cl1

Sb1−O1

Sb1−O2

2.4799(3)

2.4796(7)

2.2750(8)

2.073(3)

2.065(3)

2.5156(8)

2.203(2)

2.208(2)

2.121(3)

2.123(3)

2.4651(2)

2.4931(5)

2.2865(5)

2.117(2)

2.108(2)

2.5272(5)

2.155(2)

2.149(2)

2.120(2)

2.123(2)

2.4705(3)

2.4755(7)

2.2825(8)

2.072(2)

2.060(2)

2.5175(7)

2.212(2)

2.196(2)

2.113(6)

2.11(2)

Sb1−Ru1−Cl1

N1−Ru1−N2

P1−Ru1−Cl1

C−Sb1−C

O1−Sb1−O2

160.66(2)

172.74(10)

178.43(3)

96.71(13)

174.39(9)

126.42(9)

136.86(10)

160.17(1)

174.44(7)

178.56(2)

97.40(8)

172.52(7)

128.00(6)

134.59(6)

159.99(2)

172.73(9)

178.20(3)

94.1(8)

174.34(9)

129.1(2)

136.6(8)

124.7(9)

133.9(2)

97.0(3)

a

C−Sb1−Ru1

Cl−Sb1−Ru1

Cl−Sb1−C

Sb1−C

Sb1−Cl

2.289(7)

2.30(4)

99(1)

a

Symmetry operation: 5a: −x + 2, −y + 1, −z; 5b: −x + 1, −y + 1, −z; 6a: −x, −y + 1, −z + 1.

Scheme 4. Synthesis of Complexes of Types 6−8

therefore the presence of excess PPh₃in the reaction mixture, the

formation of monomeric complexes of the type [Ph₂Sb(μ-

L)₂RuCl(PPh₃)₂] with trans-Ph₃P−Ru−PPh₃motif has not

been observed. We attribute this preferred dimerization with

(Ru₂Cl₂)²⁺core formation to lowering of the steric repulsion

between the phenyl groups of the PPh₃and SbPh units. This

hypothesis is supported by the wider Ru1−Sb1−C angles (by

about 6−10°) at the PPh₃side in comparison to those on the Cl

side. The coordination sphere at antimony can be described as

distorted trigonal bipyramidal, with almost linear arrangement

of the O1−Sb1−O2 axis. The Sb1−Ru1 bonds are signiﬁcantly

shorter in 5a and 5b than in corresponding compounds 4a and

4b by about 0.07 Å, which may be caused by the additional

bridging ligand.

The reactions of 2a and 2b with [RuCl₂(PPh₃)₃] aﬀorded

mixtures of various products (Scheme 4). After vapor diﬀusion

of diethyl ether into the crude product mixture of the reaction

between 2a and [RuCl₂(PPh₃)₃] in chloroform, crystals suitable

for single-crystal X-ray diﬀraction could be obtained. Surpris-

ingly, the molecular structure of this product (compound 6a) is

similar to that of 5a with antimony-bound phenyl groups but

some phenyl partially replaced by Cl atoms ([R₂Sb(μ-La)₂Ru-

(PPh₃)(μ-Cl)]₂6a; R = Ph, Cl; Figure 5, Table 3). The molecule

is situated around a center of inversion (symmetry: −x, −y + 1,

−z + 1) and the Cl and Ph positions are disordered in a

21.4(6):78.6(6) ratio. The Cl/Ph ratio clearly shows that the

molecule must contain SbPh₂moieties (in addition to

disordered SbPhCl groups); therefore, both ligand scrambling

between Sb and Ru (L vs Cl exchange) and ligand scrambling

between SbPhCl moieties must have taken place. The ³¹P NMR

spectrum of the crude reaction mixture of 2b with

[RuCl₂(PPh₃)₃] exhibits six signals in the range of 48−54

ppm (13.2P), one signal at 42.1 ppm (s, 1P), one signal at 24.8

ppm (d, ²J_P,P= 291 Hz, 6.5P), one signal at 20.0 ppm (d, ²J_P,P

=

291 Hz, 6.5P), and one signal for free PPh₃(−5.4 ppm, s, 14P).

Because of the chemical shift similar to 5a and 5b, the six signals

in the range of 48−54 ppm may arise from complexes of type

[R₂Sb(μ-Lb)₂Ru(PPh₃)(μ-Cl)]₂(6b; R = Ph and Cl). The two

doublets at 24.8 and 20.0 ppm (d, J_P,P= 291 Hz) with equal

intensity show the characteristic J-coupling for trans located

2

triphenylphosphine groups at ruthenium and can be assigned to

compound 7 [PhClSb(μ-Lb)₂RuCl(PPh₃)₂], which could be

characterized by single-crystal X-ray diﬀraction (Figure 5). The

signal at 42.1 ppm can be assigned to compound 8b. Further

products (acting as Lc/Ph provider and Cl⁻scavenger) have not

been identiﬁed. To avoid the formation of such a wide product

spectrum, from which products are hard to be isolated in pure

state, 1 equiv of HLa or HLb and Et₃N as supporting base were

added to the reaction mixtures for deliberate synthesis of pure 8a

or 8b, respectively.

The coordination modes of ruthenium and antimony in the

molecular structure of 6a are very similar to compound 5a. The

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square pyramidal),¹⁹the antimony coordination spheres in

complexes of types 5 (τ = 0.63) and 6 (τ = 0.63) can be

described as intermediate but closer to trigonal bipyramidal,

whereas in complex 7b (τ = 0.49, 0.27), the Sb coordination

sphere is closer to square pyramidal.

Upon deliberate synthesis, it was possible to obtain crystals

suitable for single-crystal X-ray diﬀraction for compounds 8a

and 8b (Figure 6, Table 4). In these complexes, the antimony

Figure 6. Molecular structures of 8a (left) and 8b (right). Ellipsoids are

shown at 50% probability level. Hydrogen atoms have been omitted for

clarity.

coordination spheres (τ = 0.19 and 0.23) can be described as

close to square pyramidal (and the ruthenium coordination

sphere again as distorted octahedral). The Sb−Ru bonds are

signiﬁcantly shorter than those in complexes of type 5 by ca. 0.05

Å. For 8a and 8b, the trans-located Ru−N bonds are shorter for

the La ligand as well as for complexes of type 5, by about 0.04−

0.06 Å. Due to the trans-located PPh₃ligand, the Ru1−N2 bonds

in complexes of type 8 are signiﬁcantly longer than Ru1−N1 and

Ru1−N3 by about 0.08 Å. Accordingly, the Sb1−O2 bonds are

signiﬁcantly shorter than the corresponding Sb1−O1 and Sb1−

O3 bonds. The Ru1−P1 bonds in complexes of type 8 are

signiﬁcantly longer (by about 0.02 Å) than those in complexes of

type 5. This weaker Ru−P bonding is in accord with ³¹P NMR

spectroscopic observations: The signals of 8a and 8b are high-

ﬁeld shifted by about 10 ppm relative to the signals of 5a and 5b,

respectively.

The reactions of 3a or 3b with [RuCl₂(PPh₃)₃] in CHCl₃

resulted in the formation of diverse product mixtures. Also,

addition of HLa and Et₃N to the reaction mixture of 3a with

[RuCl₂(PPh₃)₃] did not lead to the formation of a single product

(in the ³¹P NMR spectrum of the crude reaction mixture, several

signals were observed in the range 20−55 ppm). The two main

signals at 42 and 36 ppm can be assigned respectively to

products of types 6a and 8a (with Sb−Ph replaced by Sb−La).

The ³¹P NMR spectrum of the crude reaction mixture of 3b with

[RuCl₂(PPh₃)₃] in CHCl₃exhibits two similar main signals at 40

and 56 ppm, which can be assigned respectively to products of

the type 6b and 8b (with Sb−Ph replaced by Sb−Lb). Attempts

to isolate any product via fractional crystallization failed.

To investigate the electronic features of the Sb−Ru bonds in

the deliberately synthesized compounds of types 5 and 8,

quantum chemical calculations at the DFT level were

performed. Results of the NBO/NLMO analyses are given in

Table 5. With respect to the L/X/Z-formalism of Green,¹the

charge delocalization of the bridging ligands allows for drawing

various valence bond formulas devoid of formal charges (i and

ii), and the composition of the dinuclear core (SbRu)⁵⁺could

reﬂect inherent Sb(III)→Ru(II) (i), Sb(IV)−Ru(I) (ii), and

Sb(V)←Ru(0) (iii) characteristics. Hence, the donor−acceptor

Figure 5. Molecular structures of 6a·2.5Et₂O (top) and 7b (bottom).

Ellipsoids are shown at 50% probability level. Hydrogen atoms and

solvent molecules have been omitted for clarity. The site occupancies

for the disordered Ph/Cl groups reﬁned to 4.5(4):95.5(4) Cl2/Ph and

38.3(5):61.7(5) Cl3/Ph. For 6b, only one of the two crystallo-

graphically independent (but conformationally identical) molecules is

depicted. Selected interatomic separations (Å) and angles (deg): 6a·

3Et₂O: given in Table 3. 7b: Sb−Ru 2.4682(5)−2.4587(4), Ru−N

2.131(3)−2.143(3), Ru−Cl 2.445(1)−2.448(1), Ru−P 2.396(1)−

2.470(1), Sb−O 2.139(3)−2.173(3), Sb−C 2.128(5)−2.126(4), Sb−

Cl 2.396(1)−2.374(1), Sb−Ru−Cl 172.56(3)−170.89(3), N−Ru−N

171.95(14)−171.86(13), O−Sb−O 166.95(14)−175.27(13).

average Sb−Ru bond is signiﬁcantly shorter in 6a by about 0.01

Å, which may be due to the presence of Sb−Cl moieties and the

resulting lowered steric repulsion with PPh₃. Also, the Sb−Cl

bonds can be expected to enhance π-backbonding from the Ru

atom into Sb-located σ*-orbitals. The same eﬀect of shorter Sb−

TM bond lengths upon replacing Ph by Cl have been reported

̈

by Gabbaı et al. for the complexes [RClSb(μ-C,P−

C₆H₄PPh₂)₂PtCl] with d(Sb−Pt): 2.5380(8) Å (R = Ph);

2.4407(5) Å (R = Cl).¹⁸The crystal structure of 7b contains two

crystallographically independent but conformationally identical

molecules in the asymmetric unit. Their Ru coordination

spheres are distorted octahedral. The Ru−Cl bond trans to

antimony is signiﬁcantly shorter (by about 0.05 Å) than the

corresponding Ru−Cl bond in 5b, caused by the terminal

bonding mode in 7b, whereas Cl in 5b is bridging. Also, the Sb−

Ru−Cl angle in 7b is closer to linearity (>170°). The

coordination sphere about antimony exhibits some noticeable

deviation from trigonal bipyramidal (e.g., ∠(Cl−Sb−C) ≈ 90°).

According to the geometry parameter 0 ≤ τ ≤ 1 by Addinson et

al. (with τ = 1 for ideal trigonal bipyramidal and τ = 0 for ideal

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Table 4. Selected Interatomic Separations (Å) and Angles (deg) in 8a and 8b

8a

8b

8a

8b

Ru1−Sb1

Ru1−Cl1

Ru1−P1

Ru1−N1

Ru1−N2

Ru1−N3

Sb1−O1

Sb1−O2

Sb1−O3

Sb1−C

2.427(1)

2.420(2)

2.306(1)

2.072(1)

2.156(1)

2.083(1)

2.172(1)

2.042(1)

2.181(1)

2.102(2)

2.419(1)

2.478(1)

2.314(1)

2.137(2)

2.219(2)

2.131(2)

2.117(2)

2.028(2)

2.152(2)

2.104(2)

Sb1−Ru1−Cl1

N1−Ru1−N3

N2−Ru1−P1

Ru1−Sb1−C

O1−Sb1−O3

O1−Sb1−O2

O2−Sb1−O3

O2−Sb1−C

167.12(1)

169.36(5)

174.83(4)

158.53(5)

170.02(5)

85.50(5)

84.55(5)

102.15(6)

99.31(3)

173.40(2)

170.29(8)

176.76(5)

164.02(7)

178.04(7)

90.45(8)

88.25(7)

98.96(8)

97.02(5)

O2−Sb1−Ru1

Table 5. Natural Charges (NC), Natural Bond Orbitals/

Natural Localized Molecular Orbitals (NBO/NLMO)

Characteristics, and Wiberg Bond Orders (WBOs) of 5a, 5b,

a

8a, and 8b

5a

−0.17

5b

−0.20

8a

−0.14

8b

−0.14

NC(Ru)

NC(Sb)

2.03

2.07

2.18

2.21

37.5% Ru

59.0% Sb

37.4% Ru

58.6% Sb

35.4% Ru

61.3% Sb

37.0% Ru

59.9% Sb

NLMO:

σ-(Sb−Ru)

Sb (65.2% 5s, Sb (62.4% 5s, Sb (72.5% 5s, Sb (72.1% 5s,

34.8% 5p) 37.6% 5p) 27.5% 5p) 27.9% 5p)

ΔE: π-(Sb←Ru)

7.6 7.6 23.1 21.8

0.72 0.73 0.73

(kcal mol⁻¹

)

Figure 7. NLMO representation of the σ-(Sb→Ru) bonds in 5a (left)

and NBO representation of π-(Sb←Ru) backbonding in 5a (right)

shown at an isosurface value of 0.05.

b

WBO

1.01

a

For 5a and 5b, both Sb−Ru bonds show the same results according

b

to the NBO/NLMO analysis. For NBO/NLMO analysis of 5b, the

basis set 6-311G(d) was used for the light atoms (instead of 6-

311+G(d)) because of failure of convergence with the latter. The

noticeably diﬀerent WBO may be a result of the diﬀerent basis set

used. For comparison, for 5a calculations were also performed at the

6-311G(d) level. Whereas the other results (such as NC, NLMO

composition etc.) hardly change, the eﬀect of the basis set on the

WBO was conﬁrmed (it changed from 0.72 to 1.01). ΔE are obtained

from second-order perturbation theory analysis of the Fock matrix in

NBO basis.

The topological analysis (atoms in molecules, AIM)²¹

conﬁrmed the presence of Sb−Ru bonds in 5a, 5b, 8a, and 8b

by the detection of bond critical points (BCPs, Table 8). The

ratio |V(r_b)|/G(r_b) (with V(r_b) = potential energy density, G(r_b)

= Lagrangian kinetic energy) at the BCPs is in the range of 1 < |

V(r_b)|/G(r_b) < 2²²and is thus indicative for an intermediate

bond characteristic (covalent bond with additional ionic

contribution, WBO ∼ 0.7). The NCs (Sb: 2.03−2.21; Ru:

−0.14 to −0.20 e⁻) are in support of an attractive noncovalent

bond contribution. Also, the relatively low electron density ρ(r_b)

at the BCPs together with a positive Laplacian of electron

density ∇²ρ(r_b) and similar modulus of Lagrangian kinetic

energy density and potential energy density(G(r_b) ≙ |V(r_b)|) are

in support of the presence of a closed shell bonding with donor−

acceptor characteristics.²³The G(r_b)/ρ(r_b) ratio (in the range

of 0.55−0.64) is increasing from compounds 5 to 8, thus

reﬂecting the enhanced donor role of antimony in complexes of

type 8, well in accord with the trend of atomic contributions to

the bonds observed in NLMO calculations.^23c

relation in the (SbRu)⁵⁺cores of compounds 5 and 8 may vary

between L-, X-, and Z-type Sb. NLMO analyses reveal that the

NLMOs of the σ-Sb−Ru bonds in compounds 5a, 5b, 8a, and 8b

exhibit predominant antimony contribution. Furthermore, the

hybrid orbital composition of the Sb contribution is dominated

by the 5s orbital. Both features are in accord with coordination of

an Sb-located lone pair at Ru. The σ-bond NLMOs can therefore

be interpreted as Sb→Ru bonds, i.e., Sb acting as electron pair

donor toward Ru, thus assigning L-type characteristics to Sb in

these compounds (Figures 7 and 8). In addition to the Sb→Ru

σ-donation, some d-orbitals of the Ru atoms are π-backbonding

into vacant orbitals at antimony (σ*-orbital of the O−Sb−O

4e3c bond; 5: ∼8 kcal mol⁻¹, 8: ∼8 kcal mol⁻¹). The complex

Reactivity of [PhSb(μ-L)₃RuCl(PPh₃)] toward F⁻. Ac-

̈

cording to Gabbaı et al., a chlorine−ﬂuorine exchange might

cause the transformation of the L-type characteristics of

antimony toward a transition metal into an X- or Z-type.^2a−c,18a

Reaction of 8a with TlF in chloroform under nitrogen

atmosphere resulted in the formation of compound 9a-O₂,

which could be synthesized in higher yield by injecting the

desired amount of air into the suspension (Scheme 5).

̈

[(OTf)₂Sb(o-C₆H₄(PPh₂))₂PtCl] reported by Gabbaı et al.

with slightly polarized X-type Sb−Pt bond characteristic also

shows such π-backbonding from the transition metal toward the

σ*-orbital of the O−Sb−O 4e3c bond.⁵Complexes of type 8

feature a second π-backbond (into the σ*-orbital of the O−Sb

bond) of somewhat higher intensity (∼14 kcal mol⁻¹) caused by

the diﬀerent acceptor orbital. These combinations of two

diﬀerent π-backbonds are similar to those reported for [PhP(μ-

PyO)₃Ru(κ²-PyO)].²⁰The results of NLMO/NBO analyses

indicate similarities between corresponding complexes of the

two diﬀerent bridging ligand systems, a and b.

Apparently, successful chlorine abstraction from the Ru atom

in combination with ﬂuorine coordination at Sb generates a

vacant coordination site, which is highly reactive and thus

eﬃciently traps traces of O₂. The reaction of 8b with TlF under

similar reaction conditions leads to the formation of 10b.

Whereas the same halide exchange occurs as in the formation of

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Figure 8. NLMO representation of the σ-(Sb→Ru) bond in 8a (left) and NBO representations of π-(Sb←Ru) backbonding in 8a (middle and right)

shown at an isosurface value of 0.05.

Scheme 5. Synthesis of Complexes of Types 9 and 10

Figure 9. Molecular structures of 9a-O₂·toluene (left), 9a-NCMe·2CH₂Cl₂(middle), and 10b·2CHCl₃(right). Ellipsoids are shown at 50%

probability level. Hydrogen atoms and solvent molecules have been omitted for clarity.

compound 9a-O₂, the 2-pyridyloxy ligand exhibits the capability

to act as a chelating ligand at ruthenium (similar to the

coordination in the Co→Si complex H reported by Deng et al.),

which could not be observed for the phthalimidinyl ligand. To

avoid the rapid oxidation of a possible intermediate compound,

9a (L′ = vacant site) or 9a-N₂, the reaction of 8a with TlF was

performed in acetonitrile. Desired compound 9a-NCMe is very

poorly soluble in NCMe, precipitates with TlCl/TlF, and could

not be separated from the latter because of its high oxidation

propensity. The reaction of 8a with n-Bu₄NF (anhydrous) in

NCMe leads to the formation of pure 9a-NCMe. The formation

of an analogous compound, 9b-NCMe, by adding NCMe to a

chloroform solution of 10b was not observed by NMR

spectroscopy. It was possible to determine the molecular

structures of 9a-O₂, 9a-NCMe, and 10b with single-crystal X-

ray diﬀraction (Figure 9, Table 6).

In compound 9a-O₂, the antimony atom is distorted

octahedrally coordinated as expected. The ﬂuorine atom is

trans disposed to one oxygen atom and cis to the ruthenium

atom. The Sb1−Ru1 bond is signiﬁcantly elongated with respect

to starting material 7a by about 0.22 Å, but it is still shorter than

the sum of the covalent radii (2.85 Å).²⁴The Sb1−O1 and Sb1−

O3 bonds are signiﬁcantly shorter than the Sb1−O2 bond trans

to F1 by approximately 0.08 Å. Interestingly, the Ru−N bond

lengths are similar to those in 8a. The O4−O5 bond length

(1.352(3) Å) falls between the characteristic bond lengths found

−

for superoxides (O₂, 1.2−1.3 Å) and peroxides (O₂²⁻, 1.4−1.5

Å).²⁵The WBO of 1.57 is indicative of a superoxide. Ikariya et al.

reported a [Ru(2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine)-

(O₂)(PPh₃)₂] complex, where the O−O bond length (1.36 Å)

and coordination mode are comparable to the situation found in

9a-O₂, where they assigned the O₂-motif to be of peroxide

character.²⁶From ATR-IR experiments, we found an additional

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distorted square pyramidal coordination about antimony (τ =

0.32). Within the standard deviation, the Sb1−Ru1 bond length

is similar to that of starting material 8b. The H···F1 separation

(2.58 Å) from chelating Lb ligand is slightly shorter than the sum

of the van der Waals radii (2.67 Å),²⁹indicating an attractive C−

H···F contact. The same is observed for the three H···O3

separations (2.24−2.43 Å; Σ_vdW= 2.72 Å). These attractive

interactions (their attractive nature could be conﬁrmed by NCI

calculations,³⁰see Supporting Information) stabilize this

particular chelating coordination mode with trans coordination

of N3 to P1 and O3 trans to Sb1.

Table 6. Selected Interatomic Separations (Å) and Angles

(deg) in 9a-O₂·Toluene, 9a-NCMe·2CH₂Cl₂, and 10b·

2CHCl₃

9a-O₂

9a-NCMe

10b

Ru1−Sb1

Ru1−P1

Ru1−N1

Ru1−N2

Ru1−N3

Ru1−O4/N4/O3

Ru1−O5

Sb1−O1

Sb1−O2

Sb1−O3

2.647(1)

2.396(1)

2.103(2)

2.096(2)

2.094(2)

2.038(2)

2.048(2)

2.107(3)

2.207(2)

2.133(2)

1.966(2)

2.107(3)

175.62(6)

94.30(5)

158.54(9)

88.51(7)

157.32(7)

157.51(7)

89.50(10)

177.37(8)

168.19(8)

88.45(10)

166.32(8)

2.502(1)

2.349(1)

2.087(2)

2.120(2)

2.081(2)

2.058(2)

2.419(1)

2.298(1)

2.097(4)

2.088(4)

2.114(4)

2.192(4)

The ¹⁹F NMR signal of 10b (in CDCl₃solution) at −148.8

ppm is in good agreement with a ﬂuorine atom attached to a

transition metal bound pentacoordinated antimony (−120 to

−130 ppm).²The ¹⁹F NMR shifts of 9a-NCMe (−60.7 ppm)

and 9a-O₂(−47.5 ppm) are in good accord with those of a

compound featuring ﬂuorine bonded to a hexacoordinated

antimony atom in a bimetallic Sb-TM complex.^2b,31The ³¹P

NMR shifts (in CD₂Cl₂solution) of 9a-NCMe (49.2 ppm) and

10b (49.6 ppm) are similar to those observed in their respective

starting material, 8a and 8b. The ³¹P resonance of 9a-O₂shows a

large high-ﬁeld shift (by about 33 ppm), which can be attributed

to the longer Ru−P bond in 9a-O₂with respect to that of 8a (by

about 0.09 Å). The presence of the Sb−Ru bond is evident from

the ³J_P,Fcoupling observed (∼5 Hz for 9a-O₂, 9b and 14 Hz for

9a-NCMe). In 9a-NCMe and 10b, the NCs at Ru are very

similar to their starting material, whereas the NC at Sb is

noticeably more positive (Table 7).

2.193(2)

2.269(2)

2.216(2)

1.998(1)

2.118(2)

176.08(5)

94.30(5)

168.53(7)

88.50(7)

170.78(6)

2.112(4)

1.148(4)

Sb1−F1

Sb1−C

1.925(3)

2.099(5)

P1−Ru1−N2

P1−Ru1−N3

N1−Ru1−N3

N1−Ru1−N2

Sb1−Ru1−O4/N4/O3

Sb1−Ru1−O5

O1−Sb1−O2

O1−Sb1−O3

O2−Sb1−F1

C−Sb1−F1

Ru1−Sb1−C

93.65(12)

166.56(13)

86.41(16)

172.92(18)

160.13(10)

88.26(7)

173.77(7)

164.23(6)

84.57(8)

167.71(17)

83.49(16)

96.39(19)

148.29(15)

168.68(7)

vibrational frequency at 1061 cm⁻¹for 9a-O₂which is absent in

9a-NCMe (Supporting Information). Assignment of this

resonance to the O−O stretch is supported by frequency

calculations (1059.95 cm⁻¹) at DFT level of theory. This

observation lies within the region reported for superoxides

(1050−1200 cm⁻¹).²⁵Also, the obvious increase of the NC at

Ru from 8a to 9a-O₂indicates an oxidation from Ru^IIto Ru^III.

The NC of the O₂-moiety (−0.67) is slightly less negative than

the NC at F⁻(−0.74) but more negative than the average NC at

the phthalimidinyl units (−0.42) and the antimony-bound

phenyl group (−0.43), which hints at the nature of the O₂-

moiety as a monoanionic superoxo ligand rather than a dianionic

peroxo ligand. However, compound 9a-O₂is diamagnetic;

therefore, the unpaired spins must be antiferromagnetically

coupled as previously observed for superoxo complexes

Table 7. Natural Charges (NC), NBO/NLMO

Characteristics, and Wiberg Bond Order (WBO) of 9a-O₂,

a

9a-NCMe, and 10b

9a-O₂

9a-NCMe

−0.13

10b

NC(Ru)

NC(Sb)

0.33

2.35

−0.08

2.28

2.29

39.0% Ru

57.3% Sb

Sb (69.2% 5s,

30.8% 5p)

38.0% Ru

59.0% Sb

Sb (73.2% 5s,

26.8% 5p)

34.7% Ru

61.5% Sb

Sb (70.8% 5s,

29.2% 5p)

NLMO:

σ-(Sb−Ru)

ΔE: π-(Sb←Ru)

2.9

12.3

0.66

20.2

0.76

(kcal mol⁻¹

)

WBO

0.58

a

ΔE are obtained from second order perturbation theory analysis of

27

28

the Fock matrix in NBO basis.

featuring a Co(II)-O₂or Cu(II)-O₂unit. To underline the

relevance of this hypothesis for 9a-O₂, the antiferromagnetic

coupling in this compound was demonstrated by broken

symmetry DFT calculations (see the Supporting Information

for details). In 9a-O₂the coordination sphere at ruthenium can

be described as distorted pentagonal bipyramidal. Atoms Ru1,

Sb1, N1, N3, O5, and O6 are almost in plane (Σ_{∠(at Ru)}= 359.8°)

and the P1−Ru1−N2 angle is close to 180°. In compound 9a-

NCMe, the ruthenium and antimony atoms are distorted

octahedrally coordinated. The average Sb−O bonds lengths are

increasing from 9a-O₂to 9a-NCMe. Caused by steric repulsion

between the F atom and PPh₃group, the O2−Sb1−F1 angles in

9a-O₂and 9a-NCMe are bent out of linearity by up to 16°,

whereas the N2−Ru1−P1 angles remain almost linear. Whereas

in 9a-O₂the three Ru−N bond lengths are similar, in 9a-NCMe

the Ru1−N2 bond (trans to PPh₃) is signiﬁcantly longer than

the bonds Ru1−N1 and Ru1−N3 by about 0.03−0.06 Å (albeit

less pronounced than in compound 8a). Complex 10b exhibits

distorted octahedral coordination about ruthenium and

This change can be attributed to the enhanced Sb

coordination number in combination with a highly electro-

negative (hard, ionic) additional donor atom. Therefore, the

enhanced Ru coordination number in combination with O

atoms in the Ru coordination sphere also results in a positive

shift of the NC of the Ru atom in 9a-O₂. The total increase of the

NC of the Sb−Ru core from compound 9a-NCMe to 9a-O₂(by

+0.52) can also be interpreted as a formal one-electron oxidation

(from SbRu⁺⁵to SbRu⁺⁶), in good accord with the formation of a

Ru(III) superoxo complex. In comparison between 8a and 9a-

NCMe, the Sb−Ru bond lengths are increasing from 8a to 9a-

NCMe. The antimony contribution toward the σ-(Sb→Ru)

bonds drops from 8a to 9a-NCMe by 2.3% in total. In the

bridging La ligands, the average NCs of the nitrogen atoms

decrease from 8a to 9a-NCMe (8a: −0.49; 9a-NCMe: −0.55),

and the NCs at oxygen increase (8a: −0.81; 9a-NCMe: −0.77).

This represents a charge ﬂow from O to N along the ligand

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(Ru−O) NLMOs and is therefore not available for a second π-

(Sb←Ru) backbond (into the σ*-O−Sb−O NBO as potential

acceptor, Figure 10).

The signiﬁcantly longer Sb−Ru bond in 9a-O₂(relative to 8a)

can be attributed to both the energetically less pronounced π-

backbonding and the repulsion of the positive NCs at Sb and Ru

in 9a-O₂. Compounds 9a-NCMe and 10b exhibit the expected

two π-(Sb←Ru) backbonding interactions. The energetic

contribution of the π-(Sb←Ru) backbond in 9a-NCMe is less

pronounced than in 8a, 8b or 10b, caused by competition with

two d_Ru→ π*-(NC) bonds, which involve the same d orbitals

(Σ(d_Ru→ π*-(NC)): 19.6 kcal mol⁻¹).

According to the topological analyses, compounds 9a-O₂, 9a-

NCMe and 10b exhibit characteristics of their Sb→Ru bonds

essentially similar to those of the complexes of types 5 and 8

(Table 8). Compound 9a-O₂exhibits the lowest positive

∇²ρ(r_b) (close to zero), which is indicative for a shift of the

closed shell bonding situation toward a shared shell interaction

with strong polar-covalent bond. This is supported by NLMO

analyses, where the dominance of the antimony contribution

toward the Sb→Ru bond is less pronounced in 9a-O₂.

CONCLUSIONS

■

Two new Sb,E ligands (1a and 1b), two new Sb,E₂ligands (2a

and 2b), and two new Sb,E₃ligands (3a and 3b) (E = O (a) and

N (b)) have been synthesized, and their coordination patterns

toward [RuCl₂(PPh₃)₃] have been investigated. In all cases, the

antimony atom tends to favor pentacoordination, thus supports

an uncontrolled L−Cl exchange reaction (L = phthalimidinyl

(La) and 2-pyridyloxy (Lb)). Addition of HLa or HLb together

with an supporting base to the reaction mixture allowed for the

deliberate syntheses of pure complexes of type 5 (with 2-fold

(O,N)-braced Sb−Ru bond) or complexes of type 8 (3-fold

(O,N)-braced Sb−Ru bond). The bridging ligands about the

Sb−Ru core (phthalimidinyl and 2-pyridyloxy) always adopt a

κO(Sb),κN(Ru) pattern. Hence, Sb−N bonds in ligands 2a and

3a are cleaved during the reaction, thus demonstrating that the

carboxylic amide (phthalimidinyl) is rather loosely bonded to

antimony. The Sb−Ru bonds in compounds 5 and 8 were shown

(NBO and AIM calculations) to be signiﬁcantly polarized to the

Sb atom, thus reﬂecting σ-(Sb(III)→Ru(II)) interactions with

stibino ligands of L-type. Additional π-backbonding from

suitable Ru(4d) orbitals into σ*-(O−Sb−O) or σ*-(O−Sb)

NBOs was also found. Attempts to provoke an Umpolung

toward X- or Z-type Sb ligand by F−Cl-exchange at complexes

Figure 10. NLMO representation of σ-(Sb→Ru) bond in 9a-O₂(left,

top) and NBO representations of the π-(Sb←Ru) backbonding (right,

top) and the two σ-(Ru−O) bonds (bottom) in 9a-O₂shown at an

isosurface value of 0.05.

backbone and therefore charge compensation at ruthenium.

This charge ﬂow is in accord with a slight elongation of the

average C−N bond lengths (by 0.005(4) Å) and shortening of

the C−O bond lengths (by 0.020(4) Å). Hence, an Umpolung

of the Sb→Ru bond was not present during the reaction from 8a

to 9a-NCMe. Charge delocalization and charge ﬂow through the

bridging ligand backbone served as predominant charge

compensation at Ru, thus causing only marginal shift of the

Sb−Ru bond electron pair toward Ru upon Cl/F exchange.

However, the formation of 9a-NCMe is an excellent example of

chemically controlled generation of a “free” coordination site at

ruthenium with retention of the electronic properties of the

dinuclear core.

In contrast to the situation found in 8a and 8b, only one π-

(Sb←Ru) backbond (d_xz) into the σ*-orbital of the O−Sb−F

4e3c bond is present in complex 9a-O₂. Caused by the side-on

coordinated O₂ligand, the d_yzorbital contributes to the two σ-

Table 8. Results of the Theoretical Topological Analysis of the Bond Critical Points (3, −1) between Sb and Ru in Complexes 5a,

a b

,

5b, 8a, 8b, 9a-O₂, 9a-NCMe, and 10b

5a

5b

8a

8b

9a-O₂

9a-NCMe

10b

ρ(r_b)

0.08503

0.10815

0.04921

−0.08169

1.660

0.579

−0.03248

−25.631

0.08836

0.10047

0.04830

−0.08319

1.722

0.547

−0.03489

−26.102

0.08936

0.14019

0.05712

−0.09295

1.627

0.639

−0.03583

−29.165

0.09141

0.13627

0.05723

−0.09459

1.653

0.626

−0.03736

−29.677

0.07342

0.02584

0.02639

−0.05170

1.959

0.359

−0.02531

−16.221

0.08453

0.09575

0.04795

−0.08039

1.677

0.567

−0.03244

−25.222

0.09240

0.13226

0.05719

−0.09516

1.664

0.619

−0.03798

−29.858

∇²ρ(r_b)

G(r_b)

V(r_b)

|V(r_b)|/G(r_b)

G(r_b)/ρ(r_b)

H(r_b)

E_int

a

b

For 5a and 5b, both Sb−Ru bonds show the same results according to the theoretical topological analysis. Electron density (ρ(r_b) in a.u.),

Laplacian of electron density (∇²ρ(r_b) in a.u.), Lagrangian kinetic energy density (G(r_b) in a.u.), potential energy density (V(r_b) in a.u.), ratio

|V(r_b)|/G(r_b), ratio G(r_b)/ρ(r_b) in a.u., electron energy density (H(r_b) in a.u.), ratio H(r_b)/ρ(r_b) in a.u., estimated interaction energy according to

Lepetit et al. and Espinosa et al. of E_int= 1/2 627.509469 V(r_b) in kcal mol⁻¹.^23d,e

L

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been geometry optimized using DFT-PBEPBE (M = Sb and Ru: SDD;

C, H, N, O F, P, and Cl: cc-pVTZ basis set). Complex 9b-O₂was

geometry-optimized with B3LYP-def2-TZVP def2/J RIJCOSX using

ORCA 4.1.2³⁷starting from the single-crystal X-ray structure. At the

same level of theory, analytical frequency calculations have been

performed. NBO and ELF graphics were generated using ChemCraft.³⁸

NCI,³⁰AIM,²¹and WBO³⁹calculations were carried out by using

MultiWFN⁴⁰at the same level of theory as for NBO/NLMO

calculations. Graphical representations of the NCI results were created

with VMD.⁴¹

of type 8 failed. Instead, in the case of phthalimidinyl compound

8a halide exchange may produce a vacant coordination site

which reacts with O₂or MeCN while retaining the electronic

characteristics at the dimetallic core (formation of complexes

9a-O₂, 9a-NCMe). In contrast, the 2-pyridyloxy ligand is

capable of switching from a bridging mode (compound 4b, 5b,

6b, 7b or 8b) into a chelating mode at ruthenium (compound

10b) upon replacing Ru-bound chloride by Sb-bound ﬂuoride.

EXPERIMENTAL SECTION

Synthesis of Ph₂Sb(La) (1a). First, 382 mg (2.87 mmol) of

phthalimidine was suspended in THF (3 mL). Then, 1.00 g (2.87

mmol) of Ph₂Sb(NEt₂) was added dropwise. The mixture was stirred at

60 °C for 1 h. After cooling to ambient temperature, the suspension was

ﬁltered, and the white solid was washed with THF (2 mL) and dried in

vacuo. Yield: 745 mg (1.83 mmol, 64%). ¹H NMR (500.1 MHz,

■

General Preparations. All preparations were carried out under an

atmosphere of dry argon or nitrogen using standard Schlenk

techniques. [RuCl₂(PPh₃)₃] was synthesized according to the literature

starting from elemental ruthenium.^11aPh₂SbCl and PhSbCl₂were

synthesized according to Herzog et al.¹²and used without puriﬁcation

for the synthesis of Ph₂Sb(NEt₂) and PhSb(NEt₂)₂, which were

accessible using a literature method.¹³Phthalimidine was prepared

following a literature method.³²Tetrahydrofuran (THF) and triethyl-

amine (Et₃N) were distilled from sodium/benzophenone and stored

under dry argon. Dichloromethane (DCM) was distilled from calcium

hydride and stored under argon. Chloroform (stabilized with

amylenes), n-pentane, and acetonitrile were stored over molecular

sieves 3 Å. Benzene was stored over sodium wire. All other chemicals

used were commercially available and were used without further

puriﬁcation.

3

CDCl₃): 4.00 (s, −CH₂, 2H), 7.29 (dm, J_H,H= 7.30 Hz, aryl, 1H),

7.39−7.50 (br. m, aryl, 8H), 7.52−7.56 (br. m, aryl, 4H), 7.88 (dm,

³J_H,H= 7.20 Hz, aryl, 1H). ¹³C{¹H} NMR (125.8 MHz, CDCl₃): 50.1,

122.9, 123.8, 127.8, 129.2, 129.7, 131.1, 132.3, 135.5, 141.2, 146.9,

176.2. Elemental analysis calcd (%) for C₂₀H₁₆NOSb (MW: 408.11 g

mol⁻¹): C: 58.86, H: 3.95, N: 3.43. Found: C: 59.05, H: 3.93, N: 3.44.

Synthesis of Ph₂Sb(Lb) (1b). First, 273 mg (2.87 mmol) of 2-

hydroxypyridine was suspended in THF (1 mL), and 1.00 g (2.87

mmol) of Ph₂Sb(NEt₂) was added dropwise. The suspension was

gently heated, and THF (2 mL) was added until a colorless solution had

formed. The mixture was stored at ambient temperature for 3 days. The

white solid was ﬁltered oﬀ, washed with Et₂O (2 × 2.5 mL), and dried in

vacuo. Yield: 402 mg (1.09 mmol, 38%). ¹H NMR (500.1 MHz,

CDCl₃): 6.54 (br. m, aryl, 1H), 6.73 (br. m, aryl, 1H), 7.32−7.42 (br. m,

aryl, 6H), 7.49 (m, aryl, 1H), 7.59−7.63 (br. m, aryl, 5H). ¹³C{¹H}

NMR (125.8 MHz, CDCl₃): 112.9, 113.3, 129.0, 129.5, 134.9, 139.9,

144.1, 146.6, 165.9. Elemental analysis calcd (%) for C₁₇H₁₄NOSb

(MW: 370.06 g mol⁻¹): C: 55.18, H: 3.81, N: 3.78. Found: C: 55.29, H:

3.76, N: 3.81.

Material and Equipment. Elemental analyses (C, H, and N) were

performed on a “Vario Micro Cube” analyzer (Elementar, Hanau,

Germany).

Solution NMR spectra were recorded on an “Avance III 500” or

“Ascend NanoBay 400” spectrometer (Bruker Biospin, Rheinstetten,

Germany) and internally referenced to tetramethylsilane for ¹H and ¹³

C

and externally referenced to 85% H₃PO₄for ³¹P and CFCl₃for ¹⁹F.

Signals were assigned by using ¹H, ¹H-COSY, ¹H,¹³C-HSQC, ¹H,¹³C-

HMBC, and ¹H,¹H-NOESY techniques. Individual schemes for signal

assignment are provided with each complex (where applicable). Solid-

state ³¹P{¹H} single-pulse (SP) magic angle spinning (MAS) NMR

experiments were performed on a Bruker Avance III HD 400 WB

spectrometer using 2.5 mm ZrO₂rotors.

Synthesis of PhSb(La)₂(2a). First, 345 mg (2.59 mmol) of

pthalimidine was dissolved in hot THF (5 mL), and 400 mg (1.29

mmol) of PhSb(NEt₂)₂was added dropwise. The reaction mixture was

allowed to cool to ambient temperature. The compound was obtained

as a colorless crystalline solid, suitable for single-crystal X-ray

diﬀraction, by vapor diﬀusion of Et₂O into the reaction mixture for 3

days. The supernatant was decanted, and the crystalline solid was

washed with Et₂O (3 mL) and dried in vacuo. Yield: 410 mg (0.89

mmol, 69%). ¹H NMR (400.1 MHz, CDCl₃): 4.15 (d, ²J_H,H= 17.77 Hz,

Single-crystal X-ray diﬀraction data sets were collected with ω-scans

on an “IPDS-2(T)” diﬀractometer (STOE, Darmstadt, Germany) using

Mo Kα radiation. Absorption correction was performed with XShape

using integration correction type. Structures were solved by direct

methods with ShelXS,³³and all non-hydrogen atoms were anisotropi-

cally reﬁned in full-matrix least-squares cycles against |F²| (ShelXL).³⁴

Hydrogen atoms were placed in idealized positions and reﬁned

isotropically (riding model). Selected parameters of data collection are

listed in Tables S2 −S6. Crystallographic ﬁles have been deposited with

the Cambridge Crystallographic Data Center (CCDC) and can be

obtained free of charge (for inquiry contact: CCDC, 12 Union Road,

Cambridge, CB2 1EZ, UK, fax: + 44−1223−336033, e-mail: deposit@

ccdc.cam.ac.uk) quoting the following reference numbers: CCDC

1863578 (2a), CCDC 1863579 (3a), CCDC 1863580 (2b), CCDC

1863581 (5a·2Et₂O·THF), CCDC 1863582 (3b), CCDC 1863583

(8a), CCDC 1863584 (5b·CHCl₃·Et₂O), CCDC 1863585 (7b),

CCDC 1863586 (6a·2.5Et₂O), CCDC 1863587 (8b), CCDC 1863588

(10b·2CHCl₃), CCDC 1863589 (4b·2Et₂O), CCDC 1863590 (4a·

1.38CHCl₃), CCDC 1863591 (9a-O₂·toluene), CCDC 1863592 (9a-

NCMe·2CH₂Cl₂).

2

−CH₂, 2H), 4.32 (d, J_H,H= 17.77 Hz, −CH₂−, 2H), 7.36 (m, aryl,

2H), 7.45−7.51 (br. m, aryl, 5H), 7.53 (m, aryl, 2H), 7.63 (m, aryl, 2H),

7.87 (m, aryl, 2H). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): 50.0, 123.1,

123.8, 128.0, 129.6, 130.6, 131.7, 132.0, 133.8, 144.3, 147.3, 176.9.

Elemental analysis calcd (%) for C₂₂H₁₇N₂O₂Sb (MW: 463.14 g

mol⁻¹): C: 57.05, H: 3.70, N: 6.05. Found: C: 57.16, H: 3.94, N: 5.82.

Synthesis of PhSb(Lb)₂(2b). First, 246 mg (2.59 mmol) of 2-

hydroxypyridine was dissolved in hot THF (2 mL), and 400 mg (1.29

mmol) of PhSb(NEt₂)₂was added dropwise. The reaction mixture was

allowed to attain ambient temperature after 1 h. A colorless crystalline

product, suitable for single-crystal X-ray diﬀraction, was obtained upon

vapor diﬀusion of Et₂O into the reaction mixture within 3 days. The

supernatant was decanted, and the solid was washed with Et₂O (2 mL)

and dried in vacuo. The compound is highly hygroscopic. Yield: 285 mg

(0.72 mmol, 56%). ¹H NMR (400.1 MHz, CDCl₃): 6.53−6.69 (br. m,

aryl, 4H), 7.26 (m, aryl, 1H), 7.34 (m, aryl, 2H), 7.53 (m, aryl, 2H), 7.76

(m, aryl, 2H), 7.87 (br. m, aryl, 2H). ¹³C{¹H} NMR (100.6 MHz,

CDCl₃): 112.9, 128.7, 129.0, 129.5, 132.8, 134.9, 140.6, 152.2, 167.0.

Elemental analysis calcd (%) for C₁₆H₁₃N₂O₂Sb·0.5H₂O (396.05 g

mol⁻¹): C: 48.52, H: 3.56, N: 7.07. Found: C: 48.38, H: 3.74, N: 6.97.

Synthesis of Sb(La)₃(3a). At ambient temperature 1.00 g (7.51

mmol) of phthalimidine was suspended in THF (50 mL), and 847 g

(2.50 mmol) of Sb(NEt₂)₃was added dropwise. The mixture was

stirred at 50 °C for 1 h. After cooling to ambient temperature, the

suspension was ﬁltered, and the white solid was washed with THF (5

mL) and dried in vacuo. Yield: 1.08 g (2.08 mmol, 83%). Crystals

Calculations were carried out with Gaussian09³⁵using DFT-

PBEPBE functional (M = Sb and Ru: SDD; C, H, N, O F, P, and Cl:

cc-pVTZ basis set, respectively) during geometry optimization.

(Cartesian coordinates of the optimized molecular structures are

given in the Supporting Information). NBO and NLMO calculations

have been performed using Gaussian09³⁵with the NBO6.0 package³⁶

using DFT-B3LYP functional (M = Sb and Ru: SDD; C, H, N, O F, P,

and Cl: 6-311+G(d) basis set including Douglas−Kroll−Hess second-

order scalar relativistic) for the complexes where the molecular

structures have been obtained by single-crystal X-ray diﬀraction

analysis. Prior to NBO/NLMO-analysis the H atom positions have

M

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suitable for single-crystal X-ray diﬀraction where obtained within 3 days

upon layering a THF solution of phthalimidine with pure THF and

careful addition of some drops of Sb(NEt₂)₃to the THF layer. ¹H NMR

(500.1 MHz, CDCl₃): 4.48 (s, H³, 6H), 7.41 (d, ³J_H,H= 7.50 Hz, aryl,

3H), 7.52 (dd, ³J_H,H= 7.50 Hz, ³J_H,H= 7.50 Hz, aryl, 3H), 7.58 (dd, ³J_H,H

Synthesis of [PhSb(μ-La)₃RuCl(PPh₃)] (8a).

= 7.50 Hz, ³J_H,H= 7.50 Hz, ⁴J_H,H= 1.19 Hz, aryl, 3H), 7.89 (d, ³J_H,H

=

7.50 Hz, aryl, 3H). ¹³C{¹H} NMR (125.8 MHz, CDCl₃): 49.1, 123.2,

123.7, 128.0, 131.6, 132.0, 147.6, 177.6. Elemental analysis calcd (%)

for C₂₄H₁₈N₃O₃Sb (MW: 518.18 g mol⁻¹): C: 55.63, H: 3.50, N: 8.11.

Found: C: 55.20, H: 3.81, N: 8.02.

First, 145 mg (313 μ mol) of PhSb(La )₂(2a ), 42 mg (315 μ mol) of

phthalimidine, and 60 mg (592 μ mol) of triethylamine were dissolved

in CDCl₃(5 mL) at 60 °C for 10 min. Then, 300 mg (313 μ mol) of

[RuCl₂(PPh₃)₃] was added, and the deep red solution was stirred at

ambient temperature for 4 days. The reaction was monitored by

³¹P{¹H} NMR spectroscopy. The red solution was ﬁ ltered through

Celite, and red crystals, suitable for single-crystal X-ray di ﬀ raction, were

obtained by vapor di ﬀ usion of diethyl ether into the ﬁ ltrate. The

supernatant was decanted, the solid was washed with diethyl ether (2

Synthesis of Sb(Lb)₃(3b). First, 1.69 g (17.7 mmol) of 2-

hydroxypyridine was dissolved in hot THF (10 mL), and 2.00 g (5.92

mmol) of Sb(NEt₂)₃was added dropwise. The reaction mixture was

stirred at ambient temperature for 2 h. The mixture was evaporated to

dryness, and the residue was recrystallized in THF (1.9 mL). After 3

days, colorless crystals suitable for single-crystal X-ray diﬀraction were

obtained. The supernatant was decanted, and the solid was washed with

n-pentane (1 mL) and dried in vacuo. The compound is highly

hygroscopic. Yield: 1.68 g (4.16 mmol, 70%). ¹H NMR (400.1 MHz,

CDCl₃): 6.60−6.78 (br. m, aryl, 6H), 7.57 (t, ²J_H,H= 7.72 Hz, aryl, 3H),

1

mL) and dried in vacuo . Yield: 104 mg (103 μ mol, 33%). H NMR

(500.1 MHz, CDCl₃): 3.73 (d, ²J_H,H= 21.54 Hz, H³(La -2), 2H), 4.67

(s, H³(La -1), 2H), 4.70 (d, ²J_H,H= 21.54 Hz, H³(La -2), 2H), 7.00 (m,

meta -PPh₃, 6H), 7.07 (m, para -PPh₃, 3H), 7.17−7.31 (br. m, H⁶(La -

1), H⁴(La -2), H⁵(La -1), H⁵(La -2), H⁴(La -1), H⁶(La -2), 9H), 7.41

(m, ortho -PPh₃, 6H), 7.53 (d, ³J_H,H= 7.57 Hz, H⁷(La -1), 1H), 7.60 −

2

7.83 (m, J_H,H= 7.72 Hz, aryl, 3H). ¹³C{¹H} NMR (100.6 MHz,

CDCl₃): 112.1, 114.3, 140.7, 143.7, 166.8. Elemental analysis calcd (%)

for C₁₅H₁₂N₃O₃Sb·0.5H₂O (412.04 g mol⁻¹): C: 43.62, H: 3.17, N:

10.17. Found: C: 43.76, H: 3.33, N: 10.17.

7.67 (br. m, H⁷(La -2), meta -SbPh, para -SbPh, 5H), 8.29 (dd, ³J_H,H

=

4

7.83 Hz, J_H,H= 1.77 Hz, ortho - SbPh, 2H). ¹³C{¹H} NMR (125.8

MHz, CDCl₃): 58.1 (s, C³(La -1)), 58.4 (s, C³(La -2)), 120.9 (s, C⁷

(La -2)), 121.7 (s, C⁴(La -2)), 121.9 (s, C⁷(La -1)), 122.1 (s, C⁴(La -

1)), 126.4 (s, C⁶(La -2)), 126.7 (s, C⁶(La -1)), 127.9 (s, ³J_C,P= 8.88 Hz,

meta -PPh₃), 128.2 (s, C⁵(La -2)), 128.9 (s, para -PPh₃), 129.2 (s, C⁵

(La -1)), 129.3 (s, meta -SbPh), 131.5 (s, C^7a(La -1)), 132.4 (s, para -

Synthesis of [Ph₂Sb(μ-La)₂RuCl(PPh₃)]₂(5a). First, 640 mg (1.57

mmol) Ph₂Sb(La) (1a) and 1.50 g (1.57 mmol) [RuCl₂(PPh₃)₃] were

dissolved in chloroform (3 mL) and stirred under reﬂux for 3 weeks.

209 mg (1.57 mmol) phthalimidine and 200 mg (1.98 mmol)

triethylamine were added to the deep red suspension and heating under

reﬂux was continued for additional 3 weeks. Thereafter, the mixture was

cooled to ambient temperature, ﬁltered, and the red solid was washed

with chloroform (2 mL) and dried in vacuo (1.27 g). Crystals suitable

for single-crystal X-ray diﬀraction were obtained by vapor diﬀusion of

diethyl ether into the ﬁltrate. The solid was characterized with SPMAS

³¹P NMR spectroscopy. The impure product was suspended in

chloroform (5 mL) with 30 mg (225 μmol) of phthalimidine and 60 mg

(593 μmol) of trimethylamine and stirred under reﬂux for 2 days. The

mixture was cooled to ambient temperature and ﬁltered, and the red

solid was washed with chloroform (2 × 2 mL) and dried in vacuo. Yield:

1.01 g (467 μmol, 60%). ¹H NMR (500.1 MHz, CD₂Cl₂): 3.34 (d, ²J_H,H

= 21.81 Hz, −CH₂−, 4H), 4.33 (d, ²J_H,H= 21.81 Hz, −CH₂−, 4H), 6.12

(m, aryl, 4H), 6.25−6.68 (br. m, aryl, 24H), 6.79−6.94 (br. m, aryl,

6H), 7.02 (m, aryl, 4H), 7.11−7.22 (br. m, aryl, 6H), 7.36 (m, aryl, 4H),

7.47−7.59 (br. m, aryl, 10H), 7.77 (m, aryl, 4H), 8.22 (m, aryl, 4H).

³¹P{¹H} NMR (202.5 MHz, CD₂Cl₂): 51.6 (S). SP-MAS−³¹P{¹H}

NMR (162.0 MHz, 14 kHz): 49.4 (s). Elemental analysis calcd (%) for

C₉₂H₇₄N₄O₄Cl₂P₂Sb₂Ru₂·2.8CHCl₃(MW: 2150.42 g mol⁻¹): C:

52.95, H: 3.60, N: 2.61. Found: C: 52.94, H: 3.66, N: 2.58.

2

SbPh), 132.9 (s, C^7a(La -2)), 133.0 (s, J_C,P= 9.76 Hz, ortho -PPh₃),

134.6 (s, ortho -SbPh), 138.9 (d, ¹J_C,P= 39.07 Hz, ipso -PPh₃), 139.7 (s,

ipso -SbPh), 149.6 (s, C^3a(La -2)), 150.0 (s, C^3a(La -1)), 172.7 (s, C¹

(La -1)), 173.0 (s, C¹(La -2)). ³¹P{¹H} NMR (202.5 MHz, CDCl₃):

35.7 (s). Elemental analysis calcd (%) for C₄₈H₃₈N₃O₃ClPSbRu·

0.1CHCl₃(MW: 1006.03 g mol⁻¹): C: 57.43, H: 3.82, N: 4.18. Found:

C: 57.31, H: 3.94, N: 4.17.

Synthesis of [PhSb(μ-Lb)₃RuCl(PPh₃)] (8b).

First, 101 mg (261 μ mol) of PhSb(Lb )₂(2b ), 25 mg (263 μ mol) of 2-

hydroxypyridine, 150 mg (1.48 mmol) of triethylamine, and 250 mg

(261 μ mol) of [RuCl₂(PPh₃)₃] were suspended in THF (3 mL). The

red/brown suspension was stirred at ambient temperature for 4 h and

then ﬁ ltered. Red crystals, suitable for single-crystal X-ray di ﬀ raction,

were obtained by vapor di ﬀ usion of n -pentane into the ﬁ ltrate for 3 days.

The supernatant was decanted, and the solid was washed with n -

pentane (2 mL) and dried in vacuo . Yield: 98 mg (111 μ mol, 43%). ¹H

NMR (400.1 MHz, CDCl₃): 6.15 (ddd, ³J_H,H= 6.84 Hz, ³J_H,H= 6.24

Hz, ⁴J_H,H= 1.52 Hz, H⁵(Lb -2), 2H), 6.54 (dddd, ³J_H,H= 6.90 Hz, ³J_H,H

= 6.18 Hz, ⁴J_H,H= 1.34 Hz, ⁵J_H,P= 0.76 Hz, H⁵(Lb -1), 1H), 6.66 (ddd,

³J_H,H= 8.28 Hz, ⁴J_H,H= 1.52 Hz, ⁴J_H,H= 0.53 Hz, H³(Lb -2), 2H), 6.72

(dddd, ³J_H,H= 8.29 Hz, ⁴J_H,H= 1.34 Hz, ⁵J_H,P= 1.32 Hz, ⁵J_H,H= 0.62 Hz,

H³(Lb -1), 1H), 7.01 −7.08 (m, meta -PPh₃, 6H), 7.08−7.14 (m, para -

PPh₃, 3H), 7.17 (ddd, ³J_H,H= 8.28 Hz, ³J_H,H= 6.84 Hz, ⁴J_H,H= 1.97 Hz,

H⁴(Lb -2), 2H), 7.24 −7.34 (m, ortho -PPh₃, H⁴(Lb -1), 8H), 7.51 −7.62

(m, meta -SbPh, para -SbPh, 3H), 8.17 (m, ortho -SbPh, 2H), 9.11 (ddd,

³J_H,H= 6.24 Hz, ⁴J_H,H= 1.97 Hz, ⁵J_H,H= 0.53 Hz, H⁶(Lb -2), 2H), 9.42

(dddd, ³J_H,H= 6.18 Hz, ⁴J_H,P= 2.48 Hz, ⁴J_H,H= 1.95 Hz, ⁵J_H,H= 0.62 Hz,

H⁶(Lb -1), 1H). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): 112.0 (s, C³

(Lb -2)), 112.7 (s, C³(Lb -1)), 113.1 (s, C⁵(Lb -2)), 115.3 (s, C³(Lb -

Synthesis of [Ph₂Sb(μ-Lb)₂RuCl(PPh₃)]₂(5b). First, 100 mg (270

μmol) of Ph₂Sb(Lb) (1b), 26 mg (273 μmol) of 2-hydroxypyridine,

150 mg (1.48 mmol) of triethylamine, and 259 mg (270 μmol) of

[RuCl₂(PPh₃)₃] were dissolved in ice-cooled chloroform (2.5 mL).

After 2 h, the mixture was allowed to attain ambient temperature and

was stirred for 1 week. The suspension was ﬁltered, the red solid was

washed with chloroform and dried in vacuo to aﬀord a ﬁrst fraction (55

mg). Red crystals, suitable for single-crystal X-ray diﬀraction, were

obtained by vapor diﬀusion of diethyl ether into the ﬁltrate. After 1

week, the supernatant was decanted, the crystals were washed with

chloroform (2 mL) and dried in vacuo (38 mg). Yield: 93 mg (92 μmol,

1

34%). H NMR (400.1 MHz, CD₂Cl₂): 5.48 (m, aryl, 4H), 6.38 (m,

aryl, 12H), 6.72 (m, aryl, 12H), 6.78 (m, aryl, 4H), 6.96−7.19 (br. m,

aryl, 16H), 7.46 (m, aryl, 10H), 8.06 (m, aryl, 4H), 8.30 (m, aryl, 4H).

³¹P{¹H} NMR (162.0 MHz, CD₂Cl₂): 52.8 (s). Elemental analysis

calcd (%) for C₈₀H₆₆N₄O₄Cl₂P₂Sb₂Ru₂·2.5CHCl₃(MW: 2024.36 g

mol⁻¹): C: 48.95, H: 3.41, N: 2.77. Found: C: 48.99, H: 3.51, N: 2.79.

N

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3

4

1)), 128.0 (d, J_C,P= 9.29 Hz, meta -PPh₃), 129.0 (d, J_C,P= 2.02 Hz,

para -PPh₃), 129.2 (s, meta -SbPh), 132.2 (s, para -SbPh), 133.1 (d, ²J_C,P

= 9.54 Hz, ortho -PPh₃), 134.9 (s, ortho -SbPh), 137.6 (s, ipso -SbPh),

137.7 (s, C⁴(Lb -2)), 137.8 (d, ¹J_C,P= 55.47 Hz, ipso -PPh₃), 139.0 (s, C⁴

(Lb -1)), 149.4 (d, ³J_C,P= 1.47 Hz, C⁶(Lb -1)), 153.7 (s, C⁶(Lb -2)),

166.0 (s, C²(Lb -1)), 167.7 (s, C²(Lb -2)). ³¹P{¹H} NMR (162.0 MHz,

CDCl₃): 42.2 (s). Elemental analysis calcd (%) for

C₃₉H₃₂N₃O₃ClPSbRu (MW: 879.95 g mol⁻¹): C: 53.23, H: 3.67, N:

4.78. Found: C: 53.76, H: 3.58, N: 4.63.

First, 70 mg (267 μmol) n-Bu₄NF·H₂O was dissolved in

benzene (4 mL). Moisture was removed from the mixture by

azeotropic distillation until no turbidity was visible in the

distillate (≈ 2 mL). The remaining volatiles were removed under

reduced pressure. To the oily residue of anhydrous n-Bu₄NF

thus obtained, was added 65 mg (61 μmol) [PhSb(μ-

La)₃RuCl(PPh₃)]·0.1CHCl₃(8a), and the mixture was

suspended in degassed acetonitrile (1.5 mL). The yellow

mixture was stirred at room temperature for 24 h. The solid was

ﬁltered oﬀ, washed with degassed Et₂O (1,5 mL), and dried in

vacuo. Yield: 26 mg (26 μmol, 43%). The product is poorly

soluble in NCMe and CH₂Cl₂and shows high sensitivity toward

air. Yellow crystals of the compound, suitable for single-crystal

X-ray diﬀraction, were obtained by layering TlF with a 1:1 (v/v)

−CH₂Cl₂/NCMe solution of 8a for 3 days at room temperature.

¹H NMR (500.1 MHz, NCMe-d₃): 2.16 (s, −CH₃(NCMe),

3H), 4.12 (d, ²J_H,H= 20.87 Hz, −CH₂− (La-2), 2H), 4.41 (d,

²J_H,H= 20.87 Hz, −CH₂− (La-2), 2H), 4.48 (s, −CH₂− (La-1),

2H), 7.10 (m, aryl, 6H), 7.19 (m, aryl, 3H), 7.24 (m, aryl, 1H),

7.31 (m, aryl, 15H), 7.48 (m, aryl, 1H), 7.52−7.59 (br. m, aryl,

4H), 8.40 (d, ²J_H,H= 7.75 Hz, aryl, 2H). ³¹P{¹H} NMR (202.5

Synthesis of [PhFSb(μ-La)₃Ru(O₂)(PPh₃)] (9a-O₂).

First, 100 mg (99 μmol) of [PhSb(μ-La)₃RuCl(PPh₃)]·

0.1CHCl₃(8a) and 48 mg (215 μmol) of TlF were suspended

in CHCl₃(2 mL). Air (5 mL) was injected into the Schlenk ﬂask,

and the reaction mixture was stirred at room temperature for 24

h. The red suspension was ﬁltered through Celite and washed

with chloroform. The combined ﬁltrate and washings were

evaporated to dryness under reduced pressure, and the residue

was dissolved in toluene (2 mL). After 1 week, red crystals,

suitable for single-crystal X-ray diﬀraction, were obtained after

vapor diﬀusion of n-pentane into the toluene solution. The

supernatant was decanted, and the solid was washed with n-

pentane (1 mL) and dried in vacuo. Yield: 55 mg (52 μmol,

53%). ¹H NMR (400.1 MHz, CD₂Cl₂): 2.26 (s, −CH₃

3

MHz, NCMe-d₃): 49.5 (d, J_P,F= 14.2 Hz). ¹⁹F{¹H} (470.6

MHz, NCMe-d₃): −44.9 (d, ³J_P,F= 14.2 Hz). Analysis calcd (%)

for C₅₀H₄₁N₄O₃FPSbRu (MW: 1018.69 g mol⁻¹): C: 58.95, H:

4.06, N: 5.50. Found: C: 58.84, H: 3.81, N: 5.88.

Synthesis of [PhFSb(μ-Lb)₂Ru(κ²-Lb)(PPh₃)] (10b).

(toluene), 3H), 4.03 (s, −CH₂− (La-1), 2H), 4.24 (d, ²J_H,H

=

2

20.91 Hz, −CH₂− (La-2), 2H), 4.86 (d, J_H,H= 20.91 Hz,

−CH₂− (La-2), 2H), 6.95 (m, meta-PPh₃, 6H), 7.02−7.19 (br.

m, aryl (toluene, La-1/2, ortho/para-PPh₃), 17H), 7.27−7.35

(br. m, aryl (toluene, La-1/2), 7H), 7.47 (m, para-SbPh, 1H),

7.54 (m, meta-SbPh, 2H), 7.64 (m, H⁷(La-2), 2H), 8.34 (m,

ortho-SbPh, 2H). ¹³C{¹H} NMR (100.6 MHz, CD₂Cl₂): 20.4

(−CH₃, toluene), 49.3 (C³(La-1)), 57.1 (C³(La-2)), 120.7

(La), 121.1 (La), 121.2 (La), 124.5 (La), 125.7 (toluene), 126.4

(La-1), 126.7 (d, ³J_C,P= 9.50 Hz, meta-PPh₃), 127.3 (La), 127.4

(meta-SbPh), 128.0 (toluene), 128.2 (para-PPh₃), 128.7 (La,

First, 50 mg (57 μmol) [PhSb(μ-Lb)₃RuCl(PPh₃)] (8b) and 29

mg (130 μmol) TlF were suspended in CHCl₃(2 mL) and

stirred at room temperature for 24 h. The supernatant was

decanted into a new Schlenk ﬂask. Yellow crystals, suitable for

single-crystal X-ray diﬀraction, were obtained upon vapor

diﬀusion of n-pentane into the CHCl₃solution within 1 week.

The supernatant was decanted, and the solid was washed with n-

pentane (1 mL) and dried in vacuo. Yield: 16 mg (18 μmol,

32%). ¹H NMR (500.1 MHz, CDCl₃): 6.16 (m, H⁵(Lb-1), H⁵

(Lb-2), 3H), 6.22 (d, ³J_H,H= 8.75 Hz, H³(Lb-2), 1H), 6.78 (dd,

³J_H,H= 8.25 Hz, ⁴J_H,H= 1.01 Hz, H³(Lb-1), 2H), 6.93 (m, ortho-

PPh₃, 6H), 7.07 (m, meta-PPh₃, 6H), 7.16−7.23 (m, H⁴(Lb-1),

H⁴(Lb-2), para-PPh₃, 6H), 7.39 (meta-SbPh, 2H), 7.46 (m,

para-SbPh, 1H), 7.69 (m, ortho-SbPh, 2H), 8.12 (m, H⁶(Lb-2),

1H), 8.28 (dd, ³J_H,H= 6.05 Hz, ⁴J_H,H= 1.85 Hz, H⁶(Lb-1), 2H).

¹³C{¹H} NMR (125.8 MHz, CDCl₃): 110.6−110.8 (m, C³(Lb-

2), C⁵(Lb-2)), 112.7 (s, C³(Lb-1)), 113.3 (s, C⁵(Lb-1)), 128.2

(d, ³J_C,P= 9.41 Hz, meta-PPh₃), 129.5 (s, meta-SbPh), 129.4 (d,

⁴J_C,P= 1.50 Hz, para-PPh₃), 131.3 (s, para-SbPh), 132.8 (d, ²J_C,P

3

para-SbPh), 128.9 (toluene), 129.9 (d, J_C,P= 40.59 Hz, ipso-

PPh₃), 130.1 (m, La), 131.5 (m, La), 132.9 (m, ortho-PPh₃),

133.4 (m, ortho-SbPh), 137.2 (La), 137.8 (toluene), 148.4 (d,

³J_C,P= 2.94 Hz, C^3a(La-1)), 149.3 (C^3a(La-2)), 151.7 (d, ²J_C,F

=

26.90 Hz, ipso-SbPh), 171.1 (C¹(La-1)), 172.3 (C¹(La-2)).

³¹P{¹H} NMR (202.5 MHz, CD₂Cl₂): 18.6 (d, ³J_P,F= 4.7 Hz).

¹⁹F{¹H} NMR (470.6 MHz, CD₂Cl₂): −60.7 (d, ³J_P,F= 4.7 Hz).

Elemental analysis calcd (%) for C₄₈H₃₈N₃O₅FPSbRu·0.6tol-

uene (MW: 1064.92 g mol⁻¹): C: 58.87, H: 4.05, N: 3.95.

Found: C: 58.83, H: 3.92, N: 3.98. ATR-IR: 1061 cm⁻¹(O−O).

Synthesis of [PhFSb(μ-La)₃Ru(NCMe)(PPh₃)] (9a-NCMe).

= 10.38 Hz, ortho-PPh₃), 133.2 (s, ortho-SbPh), 134.6 (d, ¹J_C,P

=

42.13 Hz, ipso-PPh₃), 137.1 (s, C⁴(Lb-1), 137.8 (s, C⁴(Lb-2),

143.0 (d, ²J_C,F= 19.42 Hz, ipso-SbPh), 149.8 (d, ³J_C,P= 7.15 Hz,

C⁶(Lb-2)), 150.2 (s, C⁶(Lb-1)), 168.1 (s, C²(Lb-1)), 178.2 (s,

C²(Lb-2)). ³¹P{¹H} NMR (202.5 MHz, CDCl₃): 49.6 (d, ³J_P,F

= 3.58 Hz). ¹⁹F{¹H} NMR (470.6 MHz, CDCl₃): −143.8 (m).

Analysis calcd (%) for C₃₉H₃₂N₃O₃FPSbRu·0.4CHCl₃(MW:

O

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Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry

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Article

911.24 g mol⁻¹): C: 51.93, H: 3.58, N: 4.61. Found: C: 51.71, H:

3.00, N: 4.80.

Substituents and Their Reactivity toward Palladium(0): Formation of

Tin-Palladium Complexes via Oxidative Addition. Inorg. Chem. 2017,

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−

́

Priver, S. H. The use of [2-C₆R₄PPh₂] (R = H, F) and related

ASSOCIATED CONTENT

* Supporting Information

The Supporting Information is available free of charge at

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carbanions as building blocks in coordination chemistry. Coord. Chem.

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cationic nickel(II). Chem. Sci. 2012, 3, 1313−1318.

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Optimized structures and their geometrical parameters,

further NBO/NLMO, WBO and NCI results and ATR-

IR and ¹H NMR spectra (PDF)

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Gericke, R.; Wagler, J. Synthesis and Oxidation of a Paddlewheel-

Shaped Rhodium/ Antimony Complex Featuring Pyridine-2-Thiolate

Ligands. Chem. - Eur. J. 2017, 23, 3447−3454. (b) Autschbach, J.;

Sutter, K.; Truflandier, L. A.; Brendler, E.; Wagler, J. Atomic

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Light on the Strength of the Metal-Silicon Interaction. Angew. Chem.,

Accession Codes

CCDC 1863578−1863592 contain the supplementary crystallo-

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

charge via www.ccdc.cam.ac.uk/data_request/cif, or by email-

ing data_request@ccdc.cam.ac.uk, or by contacting The Cam-

bridge Crystallographic Data Centre, 12 Union Road, Cam-

bridge CB2 1EZ, UK; fax: +44 1223 336033.

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Int. Ed. 2011, 50, 255−259. (d) Brendler, E.; Wachtler, E.; Heine, T.;

AUTHOR INFORMATION

Corresponding Authors

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̈

Zhechkov, L.; Langer, T.; Pottgen, R.; Hill, A. F.; Wagler, J. Stannylene

or Metallastanna(IV)ocane: A Matter of Formalism. Angew. Chem., Int.

Ed. 2011, 50, 4696−4700. (e) Wagler, J.; Hill, A. F.; Heine, T.

Palladastannatrane - a Pd^II→Sn^IVDative Bond. Eur. J. Inorg. Chem.

2008, 2008, 4225−4229. (f) Wachtler, E.; Gericke, R.; Zhechkov, L.;

Heine, T.; Langer, T.; Gerke, B.; Pottgen, R.; Wagler, J. Pyridine-2-

̈

Robert Gericke − Technische Universitat Bergakademie Freiberg,

Institut fur Anorganische Chemie, D-09596 Freiberg, Germany;

̈

orcid.org/0000-0003-4669-0206;

Email: gericker.chemie@gmail.com

̈

Jorg Wagler − Technische Universitat Bergakademie Freiberg,

thiolate bridged tin-palladium complexes with Sn(PdN₂Cl₂), Sn-

(PdN₂S₂), Sn(PdN₂C₂) and Sn(Pd₂N₄) skeletons. Chem. Commun.

Institut fur Anorganische Chemie, D-09596 Freiberg, Germany;

̈

2014, 50, 5382−5384. (g) Wachtler, E.; Gericke, R.; Brendler, E.;

orcid.org/0000-0001-5968-2331; Email: joerg.wagler@

chemie.tu-freiberg.de

̈

Gerke, B.; Langer, T.; Pottgen, R.; Zhechkov, L.; Heine, T.; Wagler, J.

Group 10-group 14 metal complexes [E-TM]^IV: the role of the group 14

site as an L, X and Z-type ligand. Dalton Trans. 2016, 45, 14252−14264.

(4) Sen, S.; Ke, I.-S.; Gabbaï, F. P. T-Shaped Gold →Stiborane

Complexes as Carbophilic Catalysts: Influence of the Peripheral

Substituents. Organometallics 2017, 36, 4224−4230.

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Author Contributions

All authors have given their approval to the ﬁnal version of the

manuscript.

Notes

(5) You, D.; Gabbaï, F. P. Unmasking the Catalytic Activity of a

Platinum Complex with a Lewis Acidic, Non-innocent Antimony

Ligand. J. Am. Chem. Soc. 2017, 139, 6843−6846.

(6) (a) Lalrempuia, R.; Iglesias, M.; Polo, V.; Sanz Miguel, P. J.;

The authors declare no competing ﬁnancial interest.

́

Fernandez-Alvarez, F. J.; Perez-Torrente, J. J.; Oro, L. A. Effective

Fixation of CO₂by Iridium-Catalyzed Hydrosilylation. Angew. Chem.,

Int. Ed. 2012, 51, 12824−12827. (b) Garces, K.; Lalrempuia, R.; Polo,

V.; Fernandez-Alvarez, F. J.; García-Orduna, P.; Lahoz, F. J.; Perez-

ACKNOWLEDGMENTS

We gratefully acknowledge the acquisition of solid-state NMR

spectra by Dr. Erica Brendler (Institut fu

TU Bergakademie Freiberg). In memory of Prof. Gerhard

Roewer.

■

́

̃

̈

r Analytische Chemie,

Torrente, J. J.; Oro, L. A. Rhodium-Catalyzed Dehydrogenative

Silylation of Acetophenone Derivatives: Formation of Silyl Enol Ethers

versus Silyl Ethers. Chem. - Eur. J. 2016, 22, 14717−14729.

(7) Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Anorganische Chemie -

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Inorg. Chem. XXXX, XXX, XXX−XXX

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Ruthenium Complexes of Stibino Derivatives of Carboxylic Amides: Synthesis and Characterization of Bidentate Sb,E, Tridentate Sb,E2, and Tetradentate Sb,E3 (E = N and O) Ligands and Their Reactivity Toward [RuCl2(PPh3)3]

DOI: 10.1021/acs.inorgchem.0c00466

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