Electronic properties of a cationic triphenylphosphine ligand decorated with a (η5-C5H5)Fe group in late-transition-metal complexes

Christian Malchau, Florian Loose, Yannick Mees, Jens Duppe, Yu Sun, Gereon Niedner-Schatteburg,

Article

Electronic Properties of a Cationic Triphenylphosphine Ligand

Decorated with a (η ‑C H )Fe Group in Late-Transition-Metal

Complexes

and Werner R. Thiel *

Cite This: https://dx.doi.org/10.1021/acs.organomet.0c00414

Read Online

ACCESS

Metrics & More

Article Recommendations

sı Supporting Information

ABSTRACT: The synthesis and characterization of a series of novel

cationic multimetallic transition-metal complexes based on the cationic

phosphine ligand (η -diphenylphosphinobenzene)(η -cyclopentadienyl)-

iron(II) hexaﬂuorophosphate (1) are reported. Complexes of ligand 1 with

the late transition metals ruthenium, osmium, rhodium, and iridium as well

as palladium and platinum were isolated in generally good yields, and the

solid-state structures of most of them were determined. On the basis of the

Pt− P NMR coupling constant measured for trans-(1) PtCl and the

carbonyl absorption band in the IR spectrum of trans-(1) Rh(CO)Cl, the

electronic inﬂuence of the ligand on the metal center was evaluated. These

measurements are supported by density functional theory (DFT)

calculations, performed on the corresponding tricarbonylnickel(0)

complex in order to determine the Tolman electronic parameter (TEP)

of ligand 1.

3c,6

INTRODUCTION

more-accepting ligands.

An entirely diﬀerent approach sets

■

the focus on positively charged phosphine ligands in order to

generate comparably strong π-accepting properties. Synthesis

strategies to access such compounds include the reaction of

chloro(dialkyl)- or chloro(diaryl)phosphines with Lewis bases,

In homogeneous catalysis, phosphines are among the most

frequently used ligands. They impart good solubility of

catalysts in organic solvents and have in particular the ability to

stabilize metal centers in lower oxidation states that are of

importance in many catalytic cycles. A further advantage is the

great variability of phosphines. This enables tailoring such

ligands in order to rationally optimize the reactivity and

selectivity of metal-centered catalysts. The Tolman steric

parameter (TSP) and the Tolman electronic parameter (TEP),

for example, allow the steric and electronic properties of

a,d,7

imidazolium carboxylates, or 2-silylimidazolium salts.

During the last few years, Alcarazo et al. in particular

developed additional methods starting from secondary

3a,d,e,8

phosphines.

Cationic phosphines have recently found

application in palladium-catalyzed cross-coupling reactions,

hydroformylation, hydrosilylation, hydroarylation, and cyclo-

3e,9

phosphine ligands to be evaluated. Although there are

isomerization, to name just a few examples.

In addition,

numerous anionic or neutral phosphines with diﬀerent σ-

donating properties, only a few ligands of this type with π-

acceptor character have been reported so far. Enhanced

acceptor properties can be realized by the introduction of a

positive charge or by strongly electron withdrawing sub-

stituents in close proximity to the phosphorus donor site.

Other typical examples are phosphorus compounds with

heteroatoms directly bonded to the phosphorus atom and

therefore energetically low lying π-acceptor orbitals such as

their use in phase-transfer catalysis and in the elucidation of

reaction mechanisms by means of electrospray ionization mass

3a,e

spectrometry has been documented.

In 2016 we reported an improved synthesis of the ligand (η -

cyclopentadienyl)(η -diphenylphosphinobenzene)iron(II)

hexaﬂuorophosphate (1), which was ﬁrst reported by Roberts

et al. in 1995. Herein ferrocene is ﬁrst reacted with

Received: June 16, 2020

PF , and phosphites. Phosphites are widely used as ligands in

catalysis. In contrast, phosphorus species with directly bound

halogens are highly toxic and air-sensitive and thus have been

reported only rarely as ligands in transition-metal chemistry.

Alternatively, phosphines having perﬂuoroalkyl and -aryl

substituents have found application as less-donating and

XXXX American Chemical Society

Organometallics XXXX, XXX, XXX−XXX

Organometallics

Article

chlorobenzene in a ligand exchange reaction to give (η -

of 2 and 3 the resonances of all protons were assigned

unambiguously. The signal of the cyclopentadienyl protons

appears at about +4.4 ppm. The resonances of the protons at

chlorobenzene)(η -cyclopentadienyl)iron(II) hexaﬂuorophos-

phate (Scheme 1). The product is then treated with lithium

the η -coordinating cymene ring are observed as two doublets

Scheme 1. Synthesis of the Cationic Phosphine Ligand 1

at about 5.5 ppm. In comparison to this, the H NMR

resonances of the η -coordinating phenyl ring are shifted to

lower ﬁeld (about +6.2 and +6.9 ppm, respectively) due to the

positively charged CpFe group that is coordinated to this

fragment. Further resonances in the aromatic region are

assigned to the two phenyl groups. Three signals in the

aliphatic region are allocated to the methyl and the isopropyl

substituents of the cymene ring. In addition to the NMR

spectra, elemental analysis and ESI mass spectrometry further

support the structural identiﬁcation. ESI mass spectrometry

shows the expected signals of the cations 2 and 3 without any

fragmentation and with matching isotope patterns.

Single crystals of the ruthenium(II) complex 2, suitable for a

X-ray diﬀraction study, were obtained by slow diﬀusion of

diethyl ether into a saturated solution of 2 in dichloromethane.

Figure 1 shows the molecular structure of 2 and summarizes

typical bond parameters.

Legend: (i) C H Cl, AlCl , NH PF , reﬂux, 4 h; (ii) LiPPh , thf, 18

h, rt.

diphenylphosphide to obtain the cationic phosphine ligand in a

nucleophilic aromatic substitution reaction. Furthermore, we

were able to synthesize the ﬁrst heterobimetallic complex with

gold(I) chloride based on this cationic phosphine ligand.

In a continuation of this work, we now report on the

synthesis and characterization of further cationic transition-

metal complexes with ligand 1 as well as on a detailed

investigation of its electronic properties.

RESULTS AND DISCUSSION

Complex Synthesis. Our attention was ﬁrst directed to

■

ruthenium and osmium, the heavy homologues of iron. The

diamagnetic compounds [(η -p-cymene)MCl ] (M = Ru, Os)

seemed to be suitable precursors. They both are known to

react readily with phosphines to yield complexes of the type

12b,13

(

η -p-cymene)MCl (L) (L = phosphine ligand).

Treat-

ment of 1/2 equiv of the dimers [(η -p-cymene)MCl ] with

phosphine 1 gave the corresponding cationic phosphine

complexes 2 and 3 in yields of 90 and 70%, respectively

(

Scheme 2).

Figure 1. Molecular structure of compound 2 in the solid state.

Characteristic bond lengths (Å) and angles (deg): Fe1−Cp

Scheme 2. Synthesis of the Ruthenium(II) and Osmium(II)

Complexes 2 and 3

.6658(5), Fe1−Ar 1.5390(5), Ru1−Cl1 2.4080(9), Ru1−Cl2

.4221(9), Ru1−P1 2.3589(9), Ru1−Ar 1.7074(3), Cp−Fe1−Ar

77.45(4), Cl1−Ru1−Cl2 88.96(3), Cl1−Ru1−P1 88.17(3), Cl1−

Ru1−Ar 124.44(2), Cl2−Ru1−P1 87.02(3), Cl2−Ru1−Ar

26.90(3), P1−Ru1−Ar 128.56(3). Cp denotes the center of the

η -coordinated cyclopentadienyl ring. Ar denotes the centers of the

η -coordinated arene rings.

While the distances between Fe1 and the carbon atoms of

the η -coordinated cyclopentadienyl ring (average 2.051 Å) are

Legend: (i) [(η -p-cymene)MCl ] , CH Cl , rt, 16 h.

slightly shorter than the distances between Fe1 and the carbon

atoms of the η -coordinated phenyl ring (average 2.088 Å), the

The ﬁrst evidence for the successful synthesis of compounds

and 3 was obtained by H and P NMR spectroscopy. The

P spectra of 2 and 3 showed in addition to the typical septet

distances to the corresponding ring centers behave in the

opposite way, due to the diﬀerent ring sizes. According to the

ionic radii of iron(II) and ruthenium(II) the Ru1−Ar distance

is about 0.16 Å longer than the Fe1−Ar distance. The Ru1−P1

distance is slightly elongated in comparison to that in the

resonance of the hexaﬂuorophosphate anion at −144.6 ppm

the resonance of the phosphine donor at +27.5 (2, M = Ru)

and −15.6 ppm (3, M = Os), respectively.

corresponding ruthenium(II) complex (η -p-cymene)-

In comparison to the free ligand 1 (singlet at −5.9 ppm)

RuCl (PPh ) (2.3438(6) Å), bearing a triphenylphosphine

with a signal in the same range as for PPh (−6.0 ppm), the

ligand. This might be interpreted as a result of a reduced σ-

donor ability due to the positively charged phosphine ligand.

Treatment of 1/2 equiv of the dimeric rhodium(I) complex

resonance for the ruthenium complex 2 is shifted to lower ﬁeld,

while coordination to an osmium center in 3 induces a high-

ﬁeld shift. Similar data have been reported in the literature for

[(CO) Rh(μ -Cl)] with ligand 1 resulted in the formation

(

η -p-cymene)RuCl (PPh ). The rather pronounced shift of

of the dicationic complex 4 in almost quantitative yield

(Scheme 3).

the phosphine resonance to higher ﬁeld observed for the third-

row transition metal osmium is in good agreement with the

Herein, two phosphines, one carbonyl, and one chlorido

ligand complete the square-planar coordination sphere at the

rhodium center. The H NMR spectrum of compound 4

shift for the corresponding triphenylphosphine complex (η -p-

cymene)OsCl (PPh ) (δ −13.2 ppm). In the H NMR spectra

Organometallics XXXX, XXX, XXX−XXX

Organometallics

Article

Scheme 3. Synthesis of the Rhodium(I) Complex 4

sensitive to the electronic situation at the rhodium(I) center,

which is determined by two phosphine ligands. For compound

−

we measured a carbonyl band at 2002 cm (ATR). The

conclusions that can be drawn from the position of this band

on the electronic properties of ligand 1 are discussed in detail

below.

In analogy to the reaction with [(η -p-cymene)MCl ] (M =

Ru, Os), ligand 1 was treated with 1/2 equiv of the dimeric

rhodium(III) and iridium(III) complexes [(η -C Me )MCl ]

2 2

Legend: (i) [(CO) Rh(μ -Cl)] , CH Cl , rt, 16 h.

(C Me = 1,2,3,4,5-pentamethylcyclopentadienyl, M = Rh,

5 5

Ir). Stirring these precursors with 1 in dichloromethane for

16 h led to the formation of 5 and 6 in 45% and 82% yields,

respectively, after crystallization (Scheme 4).

essentially resembles the spectra of 2 and 3. Generally the

resonances are slightly shifted to lower ﬁeld. The resonance of

the cyclopentadienyl ring is found at +5.03 ppm, while this

resonance appears at about +4.4 ppm in the H NMR spectra

Scheme 4. Synthesis of the Rhodium(III) and Iridium(III)

of 2 and 3. We assign this to the increased positive charge. The

Complexes 5 and 6

P NMR spectrum shows a doublet at +26.9 ppm with a J

RhP

coupling constant of 131.0 Hz. Both values are close to the

data reported for CO(Cl)Rh(PPh ) (+30.0 ppm, J = 127

Hz).

RhP

Suitable single crystals for an X-ray structure analysis were

obtained by recrystallization of 4 by slow diﬀusion of diethyl

ether into a solution in acetonitrile. Figure 2 shows the

molecular structure of 4 and summarizes typical bond

parameters.

Legend: (i) [(η -C

Me )MCl ] , CH Cl , rt, 16 h.

5 2 2 2 2

The H and ¹³C NMR spectra show slightly broadened

signals at room temperature, which may be the result of some

hindered rotations due to the bulky Cp* ring. The P NMR

supports the trend that was already observed for complexes 2

and 3: whereas the phosphorus resonance of 5 is strongly

shifted to lower ﬁeld (33.7 ppm, J_R_h_P= 146.6 Hz) in

comparison to that of 1 (−5.9 ppm), relativistic eﬀects

counteract that trend for 6 (3.2 ppm).

Recrystallization of the iridium(III) complex 6 by slow

diﬀusion of diethyl ether into a saturated solution in

dichloromethane gave single crystals suitable for a X-ray

diﬀraction study. Figure 3 shows the molecular structure of 6

and summarizes typical bond parameters.

The solid-state structure of 6 generally resembles the

structure of the ruthenium(II) complex 2. As a consequence

of the higher oxidation state of the iridium center, the P1−Ir1

Figure 2. Molecular structure of compound 4 in the solid state.

Characteristic bond lengths (Å) and angles (deg): Fe1−Cp

.6719(8), Fe1−Ar 1.5350(8), Fe2−Cp 1.6699(8), Fe2−Ar

.5315(7), Rh1−Cl1 2.3651(12), Rh1−P1 2.3331(11), Rh1−P2

.3265(11), Rh1−C47 1.812(5), O1−C47 1.155(7), Cp−Fe1−Ar

77.15(6), Cp−Fe2−Ar 177.64(6), Cl1−Rh1−P1 91.53(4), Cl1−

Rh1−P2 91.29(4), Cl1−Rh1−C47 175.66(17), P1−Rh1−P2

77.11(4), P1−Rh1−C47 88.81(15), P2−Rh1−C47 88.43(15),

Rh1−C47−O1 177.1(5). Cp denotes the center of the η -coordinated

cyclopentadienyl ring. Ar denotes the centers of the η -coordinated

arene rings.

The rhodium(I) center in compound 4 is coordinated in a

slightly distorted square-planar geometry with somewhat

widened P−Rh1−Cl1 angles (91.53(4) and 91.28(4)°) due

to the increased space requirement of the chloride ligand in

comparison to the carbonyl ligand. The structural parameters

overall resemble those measured for related complexes of the

Figure 3. Molecular structure of compound 6 in the solid state.

Characteristic bond lengths (Å) and angles (deg): Fe1−Cp

.6700(12), Fe1−Ar 1.5298(12), Ir1−Cl1 2.4090(19), Ir1−Cl2

.4065(19), Ir1−P1 2.3060(19), Ir1−Ar 1.8295(4), Cp−Fe1−Ar

77.76(9), Cl1−Ir1−Cl2 90.15(7), Cl1−Ir1−P1 89.92(7), Cl2−Ir1−

type CO(Cl)Rh(L) (L = phosphine ligand, trans orientation)

in the past.

P1 91.70(7), Cl1−Ir1−Ar 120.27(5), Cl2−Ir1−Ar 122.30(5), P1−

The close structural relationship also allows a comparison of

the energy of the CO stretching absorption in the infrared

spectrum of 4 with data from the literature. This absorption is

Ir1−Cp 131.45(5). Cp denotes the center of the η -coordinated

cyclopentadienyl ring. Ar denotes the centers of the η -coordinated

arene rings.

Organometallics XXXX, XXX, XXX−XXX

Organometallics

Pt − P coupling constants of 3681 Hz for cis -(PPh ) PtCl

Article

bond length (2.3060(19) Å) is shorter in comparison to the

P1−Ru1 bond (2.3590(9) Å), while the M−Cl bonds, which

have more ionic character, are almost identical.

Analogous to the synthesis of the rhodium complex 4,

treatment of 1 with 1 equiv of palladium(II) and platinum(II)

chlorides resulted in the formation of the square-planar,

dicationic complexes 7 and 8 (Scheme 5).

and of 2626 Hz for trans-(PPh ) PtCl . A more detailed

3 2 2

discussion of this coupling constant follows below. Single

crystals of compound 7 that were suitable for an X-ray

structure analysis were obtained by crystallization from

nitromethane/diethyl ether at 5 °C. Figure 4 shows the

molecular structure of 7 and summarizes typical bond

parameters.

Ligand Properties. A ﬁrst hint of the donor/acceptor

properties of ligand 1 can be derived from the P chemical

Scheme 5. Synthesis of the Palladium(II) and Platinum(II)

shift and in particular from the Pt− P coupling constant

measured for compound 8. Platinum(II) phosphine complexes

of the type (PR ) PtCl have been widely studied in the past.

Complexes 7 and 8

As has already been mentioned, the

Pt− P coupling

constant allows a determination of the coordination geometry

of these compounds, since its value is much larger for the cis

20,21

isomers in comparison to the trans isomers.

Already in 1967, Grim, Keiter, and McFarlane published a

NMR study on the inﬂuence of the phosphine substituents on

the chemical shifts and Pt− P coupling constants of the

Legend: (i) PdCl or PtCl , CH Cl , rt, 16 h.

trans-coordinated complexes (Ph (nBu) P) PtCl (n = 0, 1,

3−n

21b

195

). They found increasing values for the Pt− P coupling

constant for increasing numbers of phenyl substituents (n = 0,

392 Hz; n = 1, 2462 Hz; n = 2, 2531 Hz). Their data ﬁt well

to the value for trans-(PPh ) PtCl (2626 Hz). Klein Gebbink

Both complexes were characterized by elemental analysis

and ESI mass spectrometry. For the dication of complex 7 a

peak at m/z 471.97 (calcd 471.99) and for the dication of

complex 8 a peak at m/z 516.00 (calcd 516.01) were found. In

addition, P NMR spectroscopy proves the successful

synthesis of compounds 7 and 8: aside from the typical heptet

and co-workers investigated the synthesis and spectroscopic

data of trans-dichloridoplatinum complexes bearing the highly

positively charged phosphine (P(C H (m-CH NMe ) ) ) in

3 2 3

of the hexaﬂuorophosphate anion (+144.6 ppm, J_P_F= 706

combination with diﬀerent counteranions. Depending on the

solvent and the anions, coupling constants of 2627 Hz (Cl /

Hz), a singlet at +21.9 ppm is assigned to the palladium-bound

phosphorus atom in complex 7. The resonance of the

platinum-bound phosphorus site in complex 8 is observed at

−

DMSO-d ), 2652 Hz (Cl /D O), and 2684 Hz (BF /

DMSO) were found, indicating a minor inﬂuence of the

positive charges on this value. In 1986 Brune and co-workers

published a detailed study on the inﬂuence of ring-substituted

195

17.6 ppm along with the expected Pt satellites ( J

PtP

790 Hz).

While the trans orientation of the phosphine ligands in

triphenylphosphines (P(C H X ) ) (n = 1, 2) on the

5−n n 3

complex 7 was proved by X-ray structural analysis (Figure 4),

the

195

chemical shifts and the

Pt− P coupling constants of

Pt− P coupling constant unambiguously assigns an

21a

platinum dichloride complexes.

They found an excellent

identical geometry for complex 8. The literature reports e.g.

correlation of both the chemical shift and the coupling

constant with the substituent constants σ of the Hammett

195

equation. The chemical shifts and the Pt− P coupling

constants vary between +13.3 ppm/2534 Hz for the 4-NMe₂

substitution and +27.5 ppm/2787 Hz for the (3,5-CF )

substitution. Similar ﬁndings were later on reported by

Pringle and co-workers. For the trans-coordinated platinum

dichloride complex bearing two perﬂuorinated triphenylphos-

phine ligands (P(C F ) ) a chemical shift of −25.8 ppm and a

5 3

Pt− P coupling constant of 3145 Hz were reported in the

3,25

literature.

The substitution of one of the phenyl groups in

PPh by a bulky OAr unit raises the

constant of the corresponding phosphinite complex trans-

Pt− P coupling

(

Ph POAr) PtCl up to 2887 Hz. This value increases up to

2 2 2

400 Hz for phosphite complexes of the type trans-

26b,27

(

(ArylO) P) PtCl .

The trans-conﬁgured platinum(II)

phosphonite complex ((RO) PR′) PtCl has to the best of

our knowledge not been reported in the literature. Thus, the

value of 2790 Hz for the

Pt− P coupling constant of

compound 8 is comparable to that of trans-(P(C H (3,5-

CF ) ) ) PtCl but far away from the value of trans-

(

(P(C F ) ) PtCl . In contrast, the P chemical shift (+17.6

6 5 3 2 2

Figure 4. Molecular structure of compound 7 in the solid state.

Characteristic bond lengths (Å) and angles (deg): Fe1−Cp

ppm) is signiﬁcantly lower than the value measured for trans-

P(C H (3,5-CF ) ) ) PtCl .

(

.6744(5), Fe1−Ar 1.5447(5), Pd1−Cl1 2.2969(8), Pd1−P1

3 2 3 2

Further details on the ligand properties of 1 can be obtained

.3270(7), Cp−Fe1−Ar 177.07(3), Cl1−Pd1−P1 92.51(3). Cp

denotes the center of the η -coordinated cyclopentadienyl ring. Ar

from the IR spectrum of the rhodium(I) complex 4. In the

ATR-IR spectrum its carbonyl absorption is observed at 2002

denotes the centers of the η -coordinated arene rings.

Organometallics XXXX, XXX, XXX−XXX

Organometallics

Article

−

cm , indicating a relatively large blue shift in comparison to

the triphenylphosphine complex [RhCl(PPh ) CO] (1978

slightly out of this range (Table 1, entry 5). Nevertheless, our

calculations correctly reﬂect the experimentally observed trend

within the series of A, B, and Ca−Cc. The applied

computational method should therefore provide reliable results

for a diﬀerentiation among the diﬀerent types of phosphines

analyzed. In addition, the calculations show a satisfying

accuracy, independently of the charge of the complex.

−

cm ), which can be attributed to the inﬂuence of the

cationic, η -coordinating cyclopentadienyl iron(II) arene site at

the phosphine ligand. As already observed for the Pt− P

coupling constant, the introduction of positively charged but

not directly phenyl bound substituents in ligands such as

P(C H (m-CH NMe ) ) ) does not inﬂuence the CO

absorption very much (1981 cm ). Compounds of the

type [RhCl(PAr ) CO] (Ar = para-substituted phenyl group)

have been widely studied in the literature. The reported

carbonyl absorptions range from approximately 1965 cm (p-

NMe ) to 1990 cm

complexes bearing two P(C F ) or P(OMe) ligands values

of 2005 and 2005 cm , respectively, were found. In 2011

Sakai and co-workers reported the synthesis of the extremely

electron poor 2,6-bis(triﬂuoromethyl)-4-pyridyl group into

phosphines. For the carbonylchloridorhodium(I) complex

bearing two (2,6-bis(triﬂuoromethyl)-4-pyridyl)-

diphenylphosphine ligands they measured 2017 cm for the

CO stretching vibration.

(

Ligand 1 is therefore characterized by a TSP similar to that

of ferrocenyldiphenylphosphine (A) but signiﬁcantly smaller

than that of B. In contrast, the predicted TEP value of 1 is

substantially higher in comparison to those of A and B and

comes close to the data of Ca−Cc. These results underline its

acceptor properties. With its calculated TSP (132°) and TEP

3 2 3

−

(p-CF ). For the rhodium(I)

−

(2081 cm ) values, ligand 1 is within an area of the Tolman

5 3

−

stereoelectronic map that is traditionally covered by

phosphites, which is in complete agreement with the

spectroscopic data ( Pt− P coupling constant, carbonyl

absorption) measured for complexes 8 and 4. This might open

up opportunities for applications in catalytic transformations

that are performed with phosphites by avoiding e.g. the

moisture sensitivity of these compounds.

−

To get further insights into the steric and electronic

properties of the cationic phosphine ligand 1, we investigated

its Tolman steric parameter (TSP) and the Tolman electronic

parameter (TEP) by density functional theory (DFT) at the

B3LYP level using the Def2-TZVP basis set (see the

Supporting Information for details). Subsequent to the

Catalysis. To prove the applicability of ligand 1 in catalytic

reactions, we have investigated compound 2 for the transfer

hydrogenation of acetophenone with isopropyl alcohol as the

hydrogen source as well as for the isomerization of estragole

leading to anethole.

The complex [(η -p-cymene)Ru(Cl)

(PPh

)] has been

described to catalyze the transfer hydrogenation of acetophe-

determination of the calculated electronic parameter (CEP)

none with medium activity. We have carried out the reaction

for the hypothetical cationic complex [(1)Ni(CO) ] , the TEP

under the conditions reported in the Experimental Section.

was estimated by the utilization of the scaling factor (0.968)

reported by Duncan et al. for transition-metal carbonyl

While [(η -p-cymene)Ru(Cl) (PPh )] gave 81% conversion of

the substrate after 3 h, complex 2 led to only 2% conversion.

Prolonging the reaction time to 20 h resulted in 7%

conversion. These results can be explained by the mechanism

of the transfer hydrogenation process, which includes the

transfer of a hydrido ligand to the substrate, which will be more

diﬃcult due to the positive charge of complex 2.

complexes. The same was done for the previously reported,

related phosphines A, B and Ca−Cc and the corresponding,

spectroscopically characterized tricarbonylnickel(0) complexes

(

Scheme 6 and Table 1, entries 1−5)), to evaluate the

7a,32

method.

In the second reaction we investigated theisomerization of

the allylic substrate estragole to the styrene derivative anethole.

Scheme 6. Phosphine Ligands Used for the Comparison of

TSP, CEP, and TEP Data with Ligand 1

Here we compared compound 2 with both [(η -p-cymene)-

Ru(Cl) (PPh )] and [(η -p-cymene)Ru(Cl) (P(OMe) )].

Both complexes were reported to be highly active in this

reaction. Here complex 2 performs better than in the transfer

hydrogenation, giving 71% conversion under the conditions

described in the Experimental Section. However, the other two

complexes provided the product in yields >99%. Here, the

electron deﬁciency of the ligand seems not to decrease the

activity of the ruthenium complex as dramatically as in the

transfer hydrogenation. The poorer activity in comparison to

the trimethyl phosphite complex could be a result of steric

factors.

Table 1. TSP, CEP, and TEP data Calculated for the

Ni(CO) Complexes of Ligands A, B, Ca−Cc, and 1

entry

ligand

exptl TSP (deg)

CEP (cm⁻¹)

exptl TEP (cm⁻¹

)

135 (133)

2129

2140

2158

2154

2152

2150

2061 (2066)

2071 (2074)

2089 (2082)

2085 (2078)

2083 (2075)

2081

2064 (2069)

CONCLUSION

Novel cationic multimetallic complexes bearing the ligand (η -

diphenylphosphinobenzene)(η -cyclopentadienyl)iron(II)

172

129

140

121

132

■

hexaﬂuorophosphate (1) were obtained with transition metals

of groups XIII−X and completely characterized. The donor/

acceptor properties of the cationic phosphine were determined

PPh₃

124 (145)

2132

195

See ref 32a. See ref 32b. See ref 7a. See ref 2.

on the basis of spectroscopic data ( Pt− P coupling

constant, carbonyl IR absorption) as well as of theoretical

calculations. The data point out that compound 1 behaves

electronically more or less like a phosphite, meaning that it is a

weaker σ donor and a stronger π acceptor in comparison to

Calculated values of the TEPs are within the expected error

RMS = 7.5 cm ) of the calculation. Only the TEP of Cc is

−

(

Organometallics XXXX, XXX, XXX−XXX

Organometallics

Article

common triarylphosphines. We are currently investigating

some catalytic reactions, for which phosphites are typically

used, to further substantiate our results in terms of reactivity.

45.93; H, 3.22. H NMR (600 MHz, CD

(

CN): δ 7.77 (s, 8H), 7.64

t, J = 7.4 Hz, 4H), 7.58 (t, J = 7.6 Hz, 8H), 6.68 (s, 4H), 6.47 (t, J =

.2 Hz, 2H), 6.39 (t, J = 6.4 Hz, 4H), 5.03 (s, 10H) ppm. C NMR

(

151 MHz, CD CN): δ 135.5, 133.1, 131.5, 130.2, 98.2, 93.2, 89.9,

9.2, 79.3 ppm. P NMR (162 MHz, CD CN): δ 26.9 (d, J = 131.0

EXPERIMENTAL SECTION

■

Hz), −144.6 (sept, J = 706.6 Hz) ppm. IR (ATR): ν 3117 (w), 3069

w), 2002 (s), 1483 (w), 1437 (w), 1420 (w), 1312 (w), 1285 (w),

Ligand 1 was synthesized according to a procedure reported in the

(

literature. All reactions were carried out under an argon atmosphere

using standard Schlenk techniques. The solvents were either freshly

distilled or dried and degassed before use according to standard

techniques. Commercially available chemicals were purchased from

−1

093 (w), 823 (s), 749 (w), 693 (m), 555 (s), 517 (w) cm .

_D_i_c_h_l_o_r_i_d_o₍₍_η5 - c y c l o p e n t a d i e n y l ) ( η

diphenylphosphinobenzene)iron(II))(η -1,2,3,4,5-

pentamethylcyclopentadienyl)rhodium(III) Hexaﬂuorophos-

ABCR, Alfa Aesar, Sigma-Aldrich, Strem, or TCI. H, C, and

NMR spectra were recorded on Bruker Spectrospin Avance 400 and

00 spectrometers. The chemical shifts are referenced to internal

phate (5). A 62.4 mg portion (0.10 mmol) of bis(dichlorido(η -

1,2,3,4,5-pentamethylcyclopentadienyl)rhodium(III)) and 106 mg

(0.20 mmol) of 1 were stirred for 16 h in 10 mL of CH Cl at room

temperature. The solvent was removed under vacuum, and the crude

product was washed with 10 mL of Et O. Slow diﬀusion of Et O into

a saturated solution of 5 in CH Cl gave 75 mg (45%) of an orange

microcrystalline solid. Anal. Calcd for C33 FeP Rh: C, 47.34;

H, 4.21. Found: C, 47.19; H, 4.06. H NMR (600 MHz, CD CN): δ

8.02 (s, 4H), 7.73−7.56 (m, 6H), 7.00 (s, 2H), 6.24 (s, 3H), 4.39 (s,

solvent resonances. The multiplicities are reported as s = singlet, d =

doublet, t = triplet, q = quartet, sept = septet, and m = multiplet. The

NMR spectra of the iron complexes generally show slightly broadened

resonances. This might be due to some paramagnetic impurities and

hinders the assignment of P,C-coupling constants in some cases.

Infrared spectra were recorded on a JASCO FT/IK-6100

spectrometer using attenuated total reﬂection. ESI-mass spectrometric

measurements were performed on an AmaZon ETD instrument by

introducing solutions of the compound in acetonitrile. Elemental

analyses were carried out with a Vario MICRO Cube elemental

35Cl

5H), 1.28 (d, J = 3.9 Hz, 15H) ppm. C NMR (151 MHz, CD

δ 135.3, 133.2, 131.7, 129.8, 101.4, 96.1, 88.7, 87.2, 78.7, 8.8 ppm.

CN):

NMR (243 MHz, CD

= 706.5 Hz) ppm.

CN): δ 33.7 (d, J = 146.6 Hz), −144.6 (sept, J

D i c h l o r i d o ( ( η ⁵- c y c l o p e n t a d i e n y l ) ( η

analyzer at the Analytical Laboratory of the Technische Universitat

Kaiserslautern. For the X-ray structural analyses and for computa-

tional details please refer to the Supporting Information.

diphenylphosphinobenzene)iron(II))(η -1,2,3,4,5-

pentamethylcyclopentadienyl)iridium(III) Hexaﬂuorophos-

phate (6). This complex was synthesized as for compound 5 with

_D_i_c_h_l_o_r_i_d_o₍₍_η5 - c y c l o p e n t a d i e n y l ) ( η

200 mg (0.25 mmol) of bis(dichlorido(η -1,2,3,4,5-

pentamethylcyclopentadienyl)iridium(III)) and 265 mg (0.50

mmol) of 1. Yield: 390 mg (82%), orange microcrystalline solid.

diphenylphosphinobenzene)iron(II))(η -p-cymene)ruthenium-

(

II) Hexaﬂuorophosphate (2). A 200 mg portion (0.33 mmol) of

12a

bis(dichlorido(η -p-cymene)ruthenium(II))

and 345 mg (0.66

mmol) of 1 were dissolved in 10 mL of CH Cl , and the mixture

Recrystallized from CH

FeP Ir: C, 42.78; H, 3.81. Found: C, 42.51; H, 3.52.

H NMR (600 MHz, CD CN): δ 7.96 (s, 4H), 7.61 (s, 6H), 7.03 (s,

Cl /Et O. Anal. Calcd for

2 2

was stirred for 16 h at room temperature. The solvent was removed

under vacuum, and the crude product was washed with 10 mL of

Et O, yielding 492 mg (90%) of 2 as an orange powder.

35Cl

2H), 6.28 (s, 3H), 4.41 (s, 5H), 1.26 (s, 15H) ppm. C NMR (151

Crystallization from CH Cl /Et O gave orange crystals. Anal. Calcd

MHz, CD CN): δ 135.2, 133.1, 132.1, 129.6, 95.4, 95.1, 88.9, 87.4,

for C H Cl F FeP Ru: C, 47.50; H, 4.11. Found: C, 47.07; H, 4.18.

78.7, 8.3 ppm. P NMR (243 MHz, CD CN): δ 3.2 (s), −144.6

H NMR (400 MHz, CD CN): δ 7.99−7.84 (m, 4H), 7.62 (m, 6H),

.90 (s, 2H), 6.22 (m, 3H), 5.46 (d, J = 5.7 Hz, 1H), 5.25 (d, J = 6.1

(sept, J = 706.6 Hz) ppm. ESI-MS (CD CN): m/z 780.98

[C33

H35Cl

FePIr] .

Hz, 2H), 4.35 (s, 5H), 2.34 (sept, 1H), 1.88 (s, 3H), 0.79 (d, J = 6.9

D i c h l o r i d o ( b i s ( η - c y c l o p e n t a d i e n y l ) ( η -

Hz, 6H) ppm. ¹³C NMR (151 MHz, CD CN): δ 135.6, 135.0, 132.8,

diphenylphosphinobenzene)iron(II))palladium(II) Bis-

(

hexaﬂuorophosphate) (7). A 44.3 mg portion (0.25 mmol) of

29.7, 110.3, 98.9, 97.4, 95.6, 92.54, 88.7, 87.7, 87.3, 78.7, 30.8, 21.4,

₇_.₄_p_p_m_.₃1P NMR (162 MHz, CD CN): δ 27.5 (s), −144.6 (sept, J

palladium dichloride and 264 mg (0.50 mmol) of 1 were dissolved in

0 mL of CH Cl , and this mixture was stirred for 16 h at room

706.5 Hz) ppm. ESI-MS (CD CN): m/z 688.94

temperature to give a beige suspension. After removal of the solvent

under vacuum, the crude product was crystallized from CH NO /

[

C H Cl FePRu] .

33 34 2

D i c h l o r i d o ( ( η - c y c l o p e n t a d i e n y l ) ( η ⁶

Et O at 5 °C. Yield: 242 mg (79%) of beige crystals. Anal. Calcd for

diphenylphosphinobenzene)iron(II))(η -p-cymene)osmium(II)

Hexaﬂuorophosphate (3). This complex was synthesized as for

compound 2 with 47.4 mg (0.06 mmol) of bis(dichlorido(η -p-

cymene)osmium(II)) and 63.4 mg (0.12 mmol) of 1. Yield: 77.0

40Cl

12Fe

Pd: C, 44.78; H, 3.27. Found: C, 44.93; H, 3.25.

H NMR (600 MHz, CD NO ): δ 7.98−7.88 (m, 8H), 7.69 (m,

12H), 6.76 (s, 4H), 6.60 (s, 2H), 6.51 (t, J = 5.8 Hz, 4H), 5.06 (s,

12b

mg (70%) of an orange microcrystalline solid. Anal. Calcd for

10H) ppm. C NMR (151 MHz, CD NO ): δ 135.0, 132.5, 129.0,

126.8, 95.4, 92.2, 88.9, 87.9, 78.4 ppm. P NMR (162 MHz,

3 2

C H Cl F FeP Os: C, 42.92; H, 3.71. Found: C, 42.48; H, 3.67. H

NMR (400 MHz, CD CN): δ 7.90−7.76 (m, 4H), 7.65−7.53 (m,

CD NO ): δ 21.9 (s), −144.6 (sept, J = 706.5 Hz) ppm. ESI-MS

H), 7.03 (m, 2H), 6.25 (m, 3H), 5.60 (d, J = 5.5 Hz, 2H), 5.46 (d, J

6.0 Hz, 1H), 4.37 (s, 5H), 1.97 (s, 3H), 0.83 (d, J = 6.9 Hz, 6H)

(DMSO): m/z 471.96 [C H Cl Fe P Pd] .

46 40 2 2 2

D i c h l o r i d o ( b i s ( η - c y c l o p e n t a d i e n y l ) ( η -

diphenylphosphinobenzene)iron(II))platinum(II) Bis-

(hexaﬂuorophosphate) (8). This complex was synthesized as for

compound 7 with 40.0 mg (0.15 mmol) of platinum dichloride and

ppm. C NMR (151 MHz, CD CN): δ 135.3, 135.0, 132.8, 129.6,

01.6, 99.3, 95.5, 90.3, 88.8, 87.4, 84.6, 80.8, 78.7, 30.4, 21.8, 17.1

ppm. P NMR (162 MHz, CD CN): δ −15.6 (s), −144.6 (sept, J =

06.5 Hz) ppm. ESI-MS (CD CN): m/z

779.06

158 mg (0.30 mmol) of 1. Recrystallization from CH

CN/Et O.

3 2

[

C H Cl FePOs] .

Yield: 147 mg (74%) of a beige microcrystalline solid. Anal. Calcd for

33 34 2

Carbonylchlorido(bis((η -cyclopentadienyl)(η -

40Cl

F12Fe

Pt: C, 41.78; H, 3.05. Found: C, 41.93; H, 3.03. H

diphenylphosphinobenzene)iron(II)))rhodium(I) Bis-

NMR (400 MHz, CD NO ): δ 7.93 (dd, J = 12.7, 6.2 Hz, 8H), 7.69

(hexaﬂuorophosphate) (4). Stirring a solution of 50.0 mg (0.13

(dt, J = 24.9, 7.2 Hz, 12H), 6.79 (dt, J = 6.5, 3.3 Hz, 4H), 6.61 (t, J =

mmol) of bis(dicarbonyl(μ -chlorido)rhodium(I)), 100 mg (0.54

6.1 Hz, 2H), 6.53 (t, J = 6.3 Hz, 4H), 5.10 (s, 10H) ppm. C NMR

mmol) of KPF , and 273 mg (0.52 mmol) of 1 in 10 mL of CH Cl

(151 MHz, CD NO ): δ 135.5, 133.0, 129.4, 126.3, 95.0, 92.5, 89.5,

for 16 h at room temperature resulted in a yellow suspension. After

decanting of the solvent, the crude product was dissolved in 10 mL of

88.5, 78.9 ppm. P NMR (162 MHz, CD NO ): δ 17.6 (s), −144.6

(sept, J = 706.5 Hz) ppm. ESI-MS (CD CN): m/z 516.00

CH CN and the insoluble components were ﬁltered oﬀ. The solvent

[C H .Cl Fe P Pt] .

46 40 2 2 2

was removed under vacuum to give 312 mg (99%) of a yellow

microcrystalline solid, which was recrystallized from CH CN/Et O.

General Procedure for the Catalytic Transfer Hydrogena-

tion. The ruthenium catalyst (0.01 mmol) and KOH (4.95 mg, 0.075

mmol) were dissolved in isopropyl alcohol (5 mL) in a crimp-cap vial.

Anal. Calcd for C H ClF Fe OP Rh: C, 46.17; H, 3.30. Found: C,

Organometallics XXXX, XXX, XXX−XXX

Organometallics

2) (a) Tolman, C. A. Electron donor-acceptor properties of

Article

Then acetophenone (120 mg, 1.00 mmol, 117 μL) was added at a

temperature of 80 °C. Samples were taken after 3 and 20 h with

single-use syringes, ﬁltered through a short column ﬁlled with a small

REFERENCES

■

(

1) (a) Homogeneous Catalysis with Metal Phosphine Complexes;

Pignolet, L. M., Ed.; Springer: Berlin, 1983. (b) Catalytic Aspects of

Metal Phosphine Complexes; Alyea, E. C., Meek, D. W., Eds.; American

Chemical Society: Washington, DC, 1982. (c) Phosphorus(III)

Ligands in Homogeneous Catalysis: Design and Synthesis; Kamer, P.

C. J., van Leeuwen, P. W. N. M., Eds.; Wiley: Hoboken, NJ, 2012.

phosphorus ligands. Substituent additivity. J. Am. Chem. Soc. 1970 , 92 ,

953 −2956. (b) Tolman, C. A. Steric effects of phosphorus ligands in

organometallic chemistry and homogeneous catalysis. Chem. Rev.

977, 77, 313−348.

3) (a) Nicholls, L. D. M.; Alcarazo, M. Applications of α -Cationic

amount of neutral aluminum oxide and MgSO , eluted with ethyl

acetate, and analyzed by gas chromatography.

General Procedure for the Isomerization of Estragole. Either

(16.7 mg, 0.02 mmol) or bis(dichlorido(η -p-cymene)ruthenium-

(

II)) (6.12 mg, 0.01 mmol) and the corresponding phosphine or

phosphite (0.02 mmol) were dissolved in methanol (0.5 mL) in a

crimp-cap vial. Then estragole (302 mg, 2.00 mmol, 315 μL) was

added at a temperature of 80 °C. Samples were taken after 24 h with

single-use syringes, ﬁltered through a short column ﬁlled with a small

Phosphines as Ancillary Ligands in Homogeneous Catalysis. Chem.

amount of neutral aluminum oxide and MgSO , eluted with

deuterated chloroform, and analyzed by NMR spectroscopy.

Lett. 2019 , 48 , 1 −13. (b) Korenaga, T.; Sasaki, R.; Shimada, K. Highly

electron-poor Buchwald-type ligand: application for Pd-catalysed

direct arylation of thiophene derivatives and theoretical consideration

of the secondary Pd(0)-arene interaction. Dalton Trans. 2015, 44,

19642−19650. (c) Pollock, C. L.; Saunders, G. C.; Smyth, E.C.M. S.;

Sorokin, V. I. Fluoroarylphosphines as ligands. J. Fluorine Chem. 2008 ,

ASSOCIATED CONTENT

sı Supporting Information

The Supporting Information is available free of charge at

https://pubs.acs.org/doi/10.1021/acs.organomet.0c00414.

■

NMR, IR, and ESI-MS spectra, crystallographic data,

and computational details (PDF)

Cartesian coordinates of the calculated structures (XYZ)

129 , 142 −166. (d) Alcarazo, M. α -Cationic phosphines: synthesis and

applications. Chem. - Eur. J. 2014 , 20 , 7868 −7877. (e) Alcarazo, M.

Synthesis, Structure, and Applications of α -Cationic Phosphines. Acc.

Chem. Res. 2016, 49 , 1797 −1805. (f) Abe, K.; Kitamura, M.; Fujita,

H.; Kunishima, M. Development of highly electron-deficient and less

sterically-hindered phosphine ligands possessing 1,3,5-triazinyl

groups. Mol. Catal. 2018, 445, 87−93.

Accession Codes

CCDC 2006876 −2006879 contain the supplementary crys-

tallographic data for this paper. These data can be obtained

free of charge via www.ccdc.cam.ac.uk/data_request/cif , or by

emailing data_request@ccdc.cam.ac.uk , or by contacting The

Cambridge Crystallographic Data Centre, 12 Union Road,

Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

(

4) (a) Gual, A.; Godard, C.; de la Fuente, V.; Castillon

and Synthesis of Phosphite Ligands for Homogeneous Catalysis. In

ref 1c. (b) Fernandez-Perez, H.; Etayo, P.; Panossian, A.; Vidal-

Ferran, A. Chem. Rev. 2011, 111, 2119−2176.

5) (a) Drews, T.; Rusch, D.; Seidel, S.; Willemsen, S.; Seppelt, K.

Systematic reactions of Pt(PF ) . Chem. - Eur. J. 2008 , 14 , 4280 −

, S. Design

Kaiserslautern, 67663 Kaiserslautern, Germany; orcid.org/

AUTHOR INFORMATION

Corresponding Author

3 4

■

286. (b) Kruck, T. Trifluorophosphine complexes of transition

metals. Angew. Chem., Int. Ed. Engl. 1967 , 6 , 53 −67. (c) Nixon, J. F.

Trifluorophosphine complexes of transition metals. Adv. Inorg. Chem.

Werner R. Thiel − Fachbereich Chemie, Technische Universitat

000-0001-5283-2368 ; Email: thiel@chemie.uni-kl.de

985 , 29 , 41 −141. (d) Mathieu, R.; Lenzi, M.; Poilblanc, R.

Phosphorus-31 nuclear magnetic resonance study of trivalent

Authors

Christian Malchau − Fachbereich Chemie, Technische

Universitat Kaiserslautern, 67663 Kaiserslautern, Germany

Florian Loose − Fachbereich Chemie, Technische Universitat

Kaiserslautern, 67663 Kaiserslautern, Germany

Yannick Mees − Fachbereich Chemie, Technische Universitat

Kaiserslautern, 67663 Kaiserslautern, Germany; Research

Center OPTIMAS, D-67663 Kaiserslautern, Germany

Jens Duppe − Fachbereich Chemie, Technische Universitat

Kaiserslautern, 67663 Kaiserslautern, Germany

Yu Sun − Fachbereich Chemie, Technische Universitat

Kaiserslautern, 67663 Kaiserslautern, Germany

Gereon Niedner-Schatteburg − Fachbereich Chemie,

Technische Universitat Kaiserslautern, 67663 Kaiserslautern,

Germany; Research Center OPTIMAS, D-67663

B.; Tkatchenko, I. Straightforward Synthesis of Donor-Stabilised

Phosphenium Adducts from Imidazolium-2-carboxylate and Their

Electronic Properties. Eur. J. Inorg. Chem. 2007, 2007, 4877−4883.

(b) Burford, N.; Losier, P.; Phillips, A. D.; Ragogna, P. J.; Cameron,

T. S. Nitrogen ligands on phosphorus(III) Lewis acceptors: A

versatile new synthetic approach to unusual N-P structural arrange-

ments. Inorg. Chem. 2003, 42, 1087−1091. (c) Burford, N.; Ragogna,

P. J.; McDonald, R.; Ferguson, M. J. Phosphine coordination

complexes of the diphenylphosphenium cation: a versatile synthetic

methodology for P-P bond formation. J. Am. Chem. Soc. 2003 , 125 ,

Kaiserslautern, Germany; orcid.org/0000-0001-7240-6673

Complete contact information is available at:

https://pubs.acs.org/10.1021/acs.organomet.0c00414

Notes

The authors declare no competing ﬁnancial interest.

ACKNOWLEDGMENTS

■

The authors wish to thank the DFG-funded transregional

collaborative research center SFB/TRR 88 “Cooperative

eﬀects in homo- and heterometallic complexes (3MET” for

ﬁnancial support.

4404 −14410. (d) Kuhn, N.; Fahl, J.; Blas

er, D.; Boese, R. Synthese

und Eigenschaften von [Ph (Carb)P]AlCl (Carb = 2,3-Dihydro-1,3-

diisopropyl-4,5-dimethylimidazol-2-yliden) - ein stabiler Carben-

Komplex des dreiwertigen Phosphors [1]. Z. Anorg. Allg. Chem.

Organometallics XXXX, XXX, XXX−XXX

Organometallics

999 , 625 , 729 −734. (e) Kuhn, N.; Henkel, G.; Go

Article

hner, M.

(13) (a) Serron, S. A.; Nolan, S. P. Enthalpies of Reaction of ((p-

cymene)RuCl ₂ )₂ with Monodentate Tertiary Phosphine Ligands.

Importance of both Steric and Electronic Ligand Factors in a

Ruthenium(II) System. Organometallics 1995 , 14 , 4611 −4616.

(b) Huang, J.; Serron, S.; Nolan, S. P. Enthalpies of Reaction of

[(p-cymene)OsCl ] with Monodentate Tertiary Phosphine Ligands.

{Ph (Carb)P}MCl (M = Pd, Pt; Carb = 2,3-dihydro-1,3-diisopropyl-

,5dimethylimidazol-2-ylidene) - a Novel Cationic Phosphane Ligand

[

1]. Z. Anorg. Allg. Chem. 1999, 625, 1415−1416.

8) (a) Petuskova, J.; Bruns, H.; Alcarazo, M. Cyclopropenylylidene-

stabilized diaryl and dialkyl phosphenium cations: applications in

homogeneous gold catalysis. Angew. Chem., Int. Ed. 2011, 50, 3799−

Importance of Steric and Electronic Ligand Factors in an Osmium(II)

System. Organometallics 1998, 17, 4004−4008.

(14) Grim, S. O.; Yankowsky, A. W. Phosphorus-31 Nuclear

Magnetic Resonance Studies on Hydrobromides of Substituted

Triarylphosphines and Other Derivatives. J. Org. Chem. 1977, 42,

1236−1239.

802. (b) Petuskova, J.; Patil, M.; Holle, S.; Lehmann, C. W.; Thiel,

W.; Alcarazo, M. Synthesis, structure, and reactivity of carbene-

stabilized phosphorus(III)-centered trications [L P] . J. Am. Chem.

Soc. 2011, 133, 20758−20760.

9) (a) Sirieix, J.; Oßberger, M.; Betzemeier, B.; Knochel, P.

Palladium Catalyzed Cross-Couplings of Organozincs in Ionic

Liquids. Synlett 2000 , 1613 −1615. (b) Wan, Q.-X.; Liu, Y.; Lu, Y.;

Li, M.; Wu, H.-H. Palladium-Catalyzed Heck Reaction in the Multi-

Functionalized Ionic Liquid Compositions. Catal. Lett. 2008, 121,

(15) Elsegood, M. R. J.; Smith, M. B.; Sanchez-Ballester, N. M.

Dichloro(η 6-p-cymene)(triphenylphosphine)ruthenium(II). Acta

Crystallogr., Sect. E: Struct. Rep. Online 2006, 62, m2838 −m2840.

(16) (a) Krafft, M. E.; Wilson, L. J.; Onan, K. D. Synthesis and

Characterization of Rhodium(I) Amino-Olefin Complexes. Organo-

metallics 1988 , 7 , 2528 −2534. (b) McCleverty, J.; Wilkinson, G.; et al.

Dichlorotetracarbonyldirhodium (rhodium carbonyl chloride). Inorg.

Synth. 2007, 8, 211−214.

(17) Tsang, D. S.; Yang, S.; Alphonse, F.-A.; Yudin, A. K.

Stereoselective isomerization of N-allyl aziridines into geometrically

stable Z enamines by using rhodium hydride catalysis. Chem. - Eur. J.

2008, 14, 886−894.

31−336. (c) Brasse, C. C.; Englert, U.; Salzer, A.; Waffenschmidt,

H.; Wasserscheid, P. Ionic Phosphine Ligands with Cobaltocenium

Backbone: Novel Ligands for the Highly Selective, Biphasic,

Rhodium-Catalyzed Hydroformylation of 1-Octene in Ionic Liquids.

Organometallics 2000, 19, 3818−3823. (d) Brauer, D. J.; Kottsieper,

K. W.; Liek, C.; Stelzer, O.; Waffenschmidt, H.; Wasserscheid, P.

Phosphines with 2-imidazolium and para-phenyl-2-imidazolium

moieties synthesis and application in two-phase catalysis. J.

Organomet. Chem. 2001, 630 , 177 −184. (e) Li, J.; Peng, J.; Bai, Y.;

Zhang, G.; Lai, G.; Li, X. Phosphines with 2-imidazolium ligands

enhance the catalytic activity and selectivity of rhodium complexes for

hydrosilylation reactions. J. Organomet. Chem. 2010, 695, 431−436.

(18) (a) Ceriotti, A.; Ciani, G.; Sironi, A. The crystal and molecular

structure of trans-chlorocarbonylbis(triphenylphosphine)rhodium(I)

in its monoclinic form. J. Organomet. Chem. 1983, 247, 345−350.

(b) Boyd, S. E.; Field, L. D.; Hambley, T. W.; Partridge, M. G.

Synthesis and characterization of Rh[P(CH ) ] (CO)CH and

f) Chen, S.-J.; Li, Y.-Q.; Wang, P.; Lu, Y.; Zhao, X.-L.; Liu, Y.

Promotion effect of water on hydroformylation of styrene and its

derivatives with presence of amphiphilic zwitterionic phosphines. J.

Mol. Catal. A: Chem. 2015, 407, 212 −220. (g) Chen, S.-J.; Li, Y.-Q.;

Wang, Y.-Y.; Zhao, X.-L.; Liu, Y. Ionic Rh(I)-complexes containing π -

accepting and hemilabile P,N-ligands as efficient catalysts for

hydroformylation of 1-octene. J. Mol. Catal. A: Chem. 2015, 396,

Rh[P(CH ) ] (CO)Ph. Organometallics 1993, 12, 1720−1724.

3 2

(19) White, C.; Yates, A.; Maitlis, P. M.; Heinekey, D. M. (η -

Pentamethylcyclopentadienyl)rhodium and -iridium compounds.

Inorg. Synth. 2007, 29, 228−234.

(20) Snelders, D. J. M.; Siegler, M. A.; von Chrzanowski, L. S.; Spek,

A. L.; van Koten, G.; Klein Gebbink, R. J. M. Coulombic inter-ligand

repulsion effects on the Pt(II) coordination chemistry of oligoca-

tionic, ammonium-functionalized triarylphosphines. Dalton Trans.

2011, 40, 2588−2600.

8−76. (h) Chen, S.-J.; Wang, Y.-Y.; Yao, W.-M.; Zhao, X.-L.; VO-

Thanh, G.; Liu, Y. An ionic phosphine-ligated rhodium(III) complex

as the efficient and recyclable catalyst for biphasic hydroformylation

of 1-octene. J. Mol. Catal. A: Chem. 2013, 378, 293 −298. (i) Li, Y.-Q.;

Liu, H.; Wang, P.; Yang, D.; Zhao, X.-L.; Liu, Y. Immobilization of a

rhodium catalyst using a diphosphine-functionalized ionic liquid in

RTIL for the efficient and recyclable biphasic hydroformylation of 1-

octene. Faraday Discuss. 2016, 190 , 219 −230. (j) You, H.; Wang, Y.;

Zhao, X.; Chen, S.; Liu, Y. Stable Ionic Rh(I,II,III) Complexes

Ligated by an Imidazolium-Substituted Phosphine with π -Acceptor

Character: Synthesis, Characterization, and Application to Hydro-

formylation. Organometallics 2013, 32, 2698−2704. (k) Zhang, H.; Li,

Y.-Q.; Wang, P.; Lu, Y.; Zhao, X.-L.; Liu, Y. Effect of positive-charges

in diphosphino-imidazolium salts on the structures of Ir-complexes

and catalysis for hydroformylation. J. Mol. Catal. A: Chem. 2016, 411,

(21) (a) Alt, H. G.; Baumgartner, R.; Brune, H. A. Uber die

Konfigurations- und Substituenten-Abhangigkeit der Pt-Cl-Valenzsch-

wingungsfrequenzen und der P-NMR-Parameter in substituierten

cis - und trans -Dichlorobis(triphenylphosphan)platin(II)-Verbindun-

gen. Chem. Ber. 1986 , 119 , 1694 −1703. (b) Grim, S. O.; Keiter, R. L.;

McFarlane, W. A Phosphorus-31 Nuclear Magnetic Resonance Study

of Tertiary Phosphine Complexes of Platinum(II). Inorg. Chem. 1967,

6, 1133−1137. (c) Rigamonti, L.; Manassero, C.; Rusconi, M.;

Manassero, M.; Pasini, A. cis Influence in trans -Pt(PPh ) complexes.

Dalton Trans. 2009, 1206−1213.

(22) (a) Hammett, L. P. Effect of structure upon the reactions of

organic compounds. Benzene derivatives. J. Am. Chem. Soc. 1937, 59,

96 −103. (b) Keenan, S. L.; Peterson, K. P.; Peterson, K.; Jacobson, K.

Determination of Hammett Equation Rho Constant for the

Hydrolysis of p-Nitrophenyl Benzoate Esters. J. Chem. Educ. 2008,

85, 558−560.

37 −343. (l) Gu, L.; Wolf, L. M.; Zielinski, A.; Thiel, W.; Alcarazo,

M. α -Dicationic Chelating Phosphines: Synthesis and Applicaion to

the Hydroarylation of Dienes. J. Am. Chem. Soc. 2017, 139, 4948−

953.

10) Dabirmanesh, Q.; Fernando, S. I. S.; Roberts, R. M. G.

(23) Clarke, M. L.; Ellis, D.; Mason, K. L.; Orpen, A. G.; Pringle, P.

G.; Wingad, R. L.; Zaher, D. A.; Baker, R. T. The electron-poor

phosphines P{C H (CF ) -3,5}3 and P(C F ) do not mimic

Synthesis and decomplexation of (η -arene)(η -cyclopentadienyl)-

iron(II) hexafluorophosphates using microwave dielectric heating. J.

Chem. Soc., Perkin Trans. 1 1995, 46, 743−749.

6 5 3

phosphites as ligands for hydroformylation. A comparison of the

(

11) Eger, T. R.; Munstein, I.; Steiner, A.; Sun, Y.; Niedner-

coordination chemistry of P{C H (CF ) -3,5} and P(C F ) and the

6 5 3

Schatteburg, G.; Thiel, W. R. New cationic organometallic phosphane

ligands and their coordination to gold(I). J. Organomet. Chem. 2016,

unexpectedly low hydroformylation activity of their rhodium

complexes. Dalton Trans. 2005, 1294 −1300.

(24) Cobley, C. J.; Pringle, P. G. Probing the bonding of phosphines

10, 51−56.

12) (a) Bennett, M. A.; Smith, A. K. Arene Ruthenium(II)

and phosphites to platinum by NMR. Correlations of J (PtP) and

Complexes formed by Dehydrogenation of Cyclohexadienes with

Hammett substituent constants for phosphites and phosphines

coordinated to platinum(II) and platinum (0). Inorg. Chim. Acta

1997, 265, 107−115.

(25) Docherty, J. B.; Rycroft, D. S.; Sharp, D. W. A.; Webb, G. A.

Restricted Rotation and Preferred Conformations in Tris-

(pentafluorophenyl)phosphine Platinum(II) Complexes; the Mecha-

Ruthenium(III) Trichloride. J. Chem. Soc., Dalton Trans. 1974 , 233 −

41. (b) Werner, H.; Zenkert, K. Aromaten(Phosphan)metall-

Komplexe XIII *. Osmium(2)- und Osmium(O)-Komplexe mit p-

Cymen als aromatischem Liganden. J. Organomet. Chem. 1988, 345,

51−166.

Organometallics XXXX, XXX, XXX−XXX

Organometallics

nism of Helicity Reversal in a Co-ordinated Triarylphosphine. J.

Article

Chem. Soc., Chem. Commun. 1979, 336−337.

26) (a) Pandey, M. K.; Mague, J. T.; Balakrishna, M. S. Sterically

Demanding Phosphines with 2,6-Dibenzhydryl-4-methylphenyl Core:

Synthesis of Ru , Pd , and Pt Complexes, and Structural and

Catalytic Studies. Inorg. Chem. 2018, 57 , 7468 −7480. (b) Bedford, R.

B.; Hazelwood, S. L.; Albisson, D. A. Platinum Catalysts for Suzuki

Biaryl Coupling Reactions. Organometallics 2002, 21, 2599−2600.

27) Ahmad, N.; Ainscough, E. W.; James, T. A.; Robinson, S. D.

Transition-metal Complexes Containing Phosphorus Ligands. Part

IX. Triaryl Phosphite Derivatives of Palladium(II) and Platinum(II)

Dihalides. J. Chem. Soc., Dalton Trans. 1973, 1148−1150.

(

28) Snelders, D. J. M.; Kunna, K.; Muller, C.; Vogt, D.; van Koten,

G.; Klein Gebbink, R. J. M. Rh(I) coordination chemistry of

hexacationic Dendriphos ligands and their application in hydro-

formylation catalysis. Tetrahedron: Asymmetry 2010, 21, 1411 −1420.

29) (a) Serron, S.; Nolan, S. P.; Moloy, K. G. Solution

Thermochemical Study of Tertiary Phosphine Ligand Substitution

Reactions in the RhCl(CO)(PR ) System. Organometallics 1996, 15,

301−4306. (b) Egglestone, D. L.; Baird, M. C.; Lock, C. J. L.;

Turner, G. Structures of Square-pyramidal Acyl and Octahedral Alkyl

Intermediates in the Decarbonylation of Acid Halides by Chlorotris-

triphenylphosphine)rhodium(I). J. Chem. Soc., Dalton Trans. 1977 ,

576 −1582. (c) Oro, L. A.; Heras, J. V. Preparation and Reactions of

Five-coordinate Rh(NBD)[P(p-Cl-C H ) ] X Complexes. Inorg.

4 3 2

Chim. Acta 1979 , 32 , L37 −L38. (d) Otto, S.; Roodt, A. Quantifying

the electronic cis effect of phosphine, arsine and stibine ligands by use

of rhodium(I) Vaska-type complexes. Inorg. Chim. Acta 2004 , 357 , 1 −

0. (e) Strohmeier, W.; Rehder-Stirnweiss, W. Anderung der

Elektronendichte am Zentralatom des Katalysators RhX(CO)L ₂

durch die Liganden X und L. Z. Naturforsch., B: J. Chem. Sci. 1970,

5b, 549 −550. (f) Wang, K.; Goldman, M. E.; Emge, T. J.; Goldman,

A. S. Transfer-dehydrogenation of alkanes catalyzed by rhodium(I)

phosphine complexes. J. Organomet. Chem. 1996, 518, 55−68.

(

30) Korenaga, T.; Ko, A.; Uotani, K.; Tanaka, Y.; Sakai, T. Angew.

Chem., Int. Ed. 2011, 50, 10703−10707.

(

31) Assefa, M. K.; Devera, J. L.; Brathwaite, A. D.; Mosley, J. D.;

Duncan, M. A. Vibrational scaling factors for transition metal

carbonyls. Chem. Phys. Lett. 2015, 640, 175−179.

(

32) (a) Schaarschmidt, D.; Kuhnert, J.; Tripke, S.; Alt, H. G.; Gorl,

C.; Ruffer, T.; Ecorchard, P.; Walfort, B.; Lang, H. Ferrocenyl

phosphane nickel carbonyls: Synthesis, solid state structure, and their

use as catalysts in the oligomerization of ethylene. J. Organomet. Chem.

010, 695, 1541−1549. (b) Buchgraber, P.; Mercier, A.; Yeo, W. C.;

Besnard, C.; Kundig, E. P. Functionalization of Planar Chiral Fused

Arene Ruthenium Complexes: Synthesis, X-ray Structures, and

Spectroscopic Characterization of Monodentate Triarylphosphines.

Organometallics 2011, 30, 6303−6315.

(

33) Carriedo, G. A.; Crochet, P.; Alonso, F. J. G.; Gimeno, J.; Presa-

Soto, A. Eur. J. Inorg. Chem. 2004, 3668−3674.

34) Menendez-Rodríguez, L.; Crochet, P.; Cadierno, V. Curr. Green

Chem. 2013, 1, 128−135.

(