Cationic Group 4 Complexes (M = Ti, Zr, Hf): Modifications and Limitations in the Design of Tridentate Cp,O,P-Ligand Frameworks Built Directly in the Coordination Sphere of the Metal

A Journal of

Accepted Article

Title: Cationic Group 4 Complexes (Ti, Zr, Hf): Modifications

and Limitations in the Design of Tridentate Cp,O,P-Ligand

Frameworks Built Directly in the Coordination Sphere of the Metal

Authors: Malte Fischer, Maximilian Jaugstetter, Raoul Schaper, Marc

Schmidtmann, and Ruediger Beckhaus

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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201801016

Link to VoR: http://dx.doi.org/10.1002/ejic.201801016

10.1002/ejic.201801016

European Journal of Inorganic Chemistry

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Cationic Group 4 Complexes (M = Ti, Zr, Hf): Modifications and

Limitations in the Design of Tridentate Cp,O,P-Ligand

Frameworks Built Directly in the Coordination Sphere of the Metal

Malte Fischer,^[a]Maximilian Jaugstetter,^[a]Raoul Schaper,^[a]Marc Schmidtmann,^[a]and Rüdiger

Beckhaus*^[a]

Abstract: The reactions of the monopentafulvene complexes Ti1,

Zr1, and Hf1 with bidentate O,P-ligand precursors L1-3 to form the

corresponding cationic complexes employing an established three-

step synthetic protocol (insertion, methylation, activation with

B(C₆F₅)₃) are investigated. The ligands L1-3 are designed to have

different sized spacers between the carbonyl and diphenylphosphine

functional groups. The attempts to react Ti1, Zr1, and Hf1 with

acetyldiphenylphosphine (L1) proved to yield undesired products at

various steps in the synthetic sequence. Employing Ti1 the

formation of Ti2 is observed accompanied by release of

diphenylphosphine. Ti2, with the exocyclic double bond, is the formal

product of insertion of the smallest ketene (H₂C=C=O) into the Ti–

C_exobond. Starting with Zr1 results in isolation of the insertion

product Zr2 without loss of diphenylphosphine, but a byproduct is

formed during the reaction with L1. Subsequent methylation with

methyllithium yielded a complex reaction mixture. Hf1 reacts cleanly

with L1 to the insertion product Hf2. Also, the methylation reaction

selectively yielded Hf3 as the result of chloride/methyl exchange, but

final activation with B(C₆F₅)₃causes decomposition and release of

diphenylphosphine. The use of the ligand precursors L2 and L3 with

two methylene groups or an aryl group as linkers between the

functional groups selectively yielded the desired cationic complexes

Ti6, Zr6, Hf6, and Ti9 in good to excellent overall yields.

group 4 metal complexes and their role as important olefin

polymerization catalysts, numerous substitution patterns for the

ancillary ligand systems have been developed do direct their

catalytic activity.^[2]For example, Brintzinger et al. synthesized a

silaspiro zirconocene complex, which posseses C₂-symmetry,

and showed that this complex is able to polymerize propylene to

isotactic polypropylene after activation with methylaluminoxan

(MAO) to the corresponding cationic complex.^[3]In contrast a

quite similar C_s-symmetric complex affords almost only atactic

polypropylene.^[4]

Cationic group 4 species receive growing interest as Lewis acid

components in frustrated Lewis pair chemistry.^[5]Such transition

metal based frustrated Lewis pairs (tm-FLPs) benefit from the

overall greater structural diversity compared to their main group

counterparts and, beyond that, show a long history as Lewis

acid catalysts in numerous reactions.^[6]The fact that the

appropriate ligand system, and assumingly even slight changes

within the ligand-framework can have a tremendous influence on

the reactivity, can be exemplified by the cationic zirconocene

phosphinoaryloxide complexes I and II by Wass and co-

workers.^[7]Whereas the dicyclopentadienyl derivative I with a

long but persistent zirconium–phosphorus bond is not able to

cleave

dihydrogen

heterolytically,

the

dipentamethylcyclopentadienyl derivative II, which shows no

interaction between the Lewis acidic zirconium center and the

Lewis basic phosphine moiety at all, readily cleaves dihydrogen

under the same reaction conditions to give complex III (Scheme

1, A).

Introduction

Ligand design is one of the key features of modern

organometallic and transition metal based chemistry with

homogeneous catalysis as the main area of application.^[1]

Bonding interactions between the central metal atom and the

ancillary ligand system prove to be crucial for influencing the

electronic properties of the complexes as well as the steric

environment around the reactive part of the molecules.

Therefore even small changes in the ligand system can be

essential to allow for further reactivity or to make new reactions

pathways accessible.

In regard to the achievements of the use of well-defined cationic

[a]

M. Fischer, M. Jaugstetter, R. Schaper, M. Schmidtmann, Prof. Dr.

R. Beckhaus,

Institut für Chemie,

Fakultät für Mathematik und Naturwissenschaften,

Carl von Ossietzky Universität Oldenburg,

Postfach 2503, 26111 Oldenburg (Germany)

Fax: (+49) 441-798-3581

e-mail: ruediger.beckhaus@uni-oldenburg.de

https://www.uni-oldenburg.de/ac-beckhaus/

Supporting information for this article is given via a link at the end of

the document

10.1002/ejic.201801016

European Journal of Inorganic Chemistry

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Wass et al.

A)

(ref 7):

continuation of our efforts, we herein report on limitations and

possibilities to expand and modify the tridentate Cp,O,P-ligand

framework of this family of cationic complexes with focus on the

ring size of the resulting M,O,P-heterocycles (Scheme 2).

^tBu₂

P

H

no reaction

Zr

F_{5 4}

)

Cp₂

B(C₆

O

I

work

molecules

11):

R

molecules

Target

(ref

Ph

Br

R

P

H

R

*

R

P

M

P

M

O

M

Zr

Cp₂

Zr

Cp₂

F_{5 4}

)

F_{5 4}

)

B(C₆

O

-

BrPh

H

O

P^tBu₂

R

P^tBu₂

R

,

, , ,

-unit

P

,C,

four-membered M O

P

five-membered M O C C P

six-membered M O C C

,C,

Scheme 2. Targeted cationic group 4 metal complexes of this work.

II

III

work:

B)

FG

Results and Discussion

A

R₂

P

insertion

Cl

δ⁺

Attempts to synthesize Cationic Group

Complexes With Four-Membered M,O,C,P-units

4

Metal

M

D

δ⁻

R

The bidentate P,O-ligand precursor L1 was prepared according

to a slightly modified method described by Wang and co-workers

and isolated as a colorless oil in 88% yield (Scheme 3).^[14]

C_exo

-

tridentate

framework

built directly in the coordination

ligand

of the metal

sphere

=

M

Ti, Zr, Hf

mild reaction conditions

to excellent

good

yields

Scheme 1. Effects of ligand design on cationic group 4 metal complexes

within tm-FLP chemistry (A) and synthetic concept of cationic group 4 metal

complexes with tridentate Cp,D,P-ligand framework (B) (M = Ti, Zr, Hf; FG =

RC=O or CN; D = O, N; R = alkyl, aryl).

O

+

HPPh₂NEt₃

Et

-

rt, 2 h

₃Cl

P

₂O,

HNEt

Cl

Previously, we have established an efficient synthetic protocol

for the synthesis of cationic complexes of all group 4 metals with

tridentate Cp,D,P-ligand frameworks (D = O, N) by reacting

L1

,

88%

mixed

cyclopentadienyl/monopentafulvene

precursor

Scheme 3. Synthesis of the ligand precursor L1.

complexes^[8-10]with bifunctional ligand precursors (Scheme 1,

B).^[11,12]Those bidentate ligand precursors feature one functional

group (FG), which is able to undergo an insertion reaction into

the polarized bond between the metal and the exocyclic carbon

atom (C_exo) of the π-η⁵:σ-η¹bonded monopentafulvene ligand

(carbonyl or nitrile functional group) and one phosphine

functional group to enable interactions between the Lewis acidic

metal center and the Lewis basic phosphine moiety in the

cationic complexes. This concept includes the characteristics of

hemilabile O,P-ligands, in which the unoccupied coordination

side can become available for further reactions by cleavage of

the labile metal–ligand bond.^[13]Recent investigations have

already shown that our reported complexes act as tm-FLPs.^[12]

In most cases, multidentate ligand precursors are synthesized

by multistep organic syntheses, which require multiple isolation

and purification steps before synthesizing the corresponding

complexes. In contrast, our approach allows the preparation of

densely functionalized Cp,D,P-tridentate ligands directly in the

coordination sphere of the respective group 4 metals in good to

excellent yields and under mild reaction conditions.^[11,12]As a

For reasons of comparison we recollected NMR data of L1 in

deuterobenzene (δ(³¹P{¹H}) = 17.0 ppm^[15]). With L1 in hand we

envisaged to synthesize cationic group 4 metal complexes (M =

Ti, Zr, Hf) with tridentate Cp,O,P-ligand framework and a

four-membered M,O,C,P-chelating subunit by employing the

established synthetic pathway reported previously.^[11,12]

Therefore, we started with the reaction of the mixed

pentamethylcyclopentadienyl/pentafulvene titanium complex Ti1

with L1 in n-hexane at room temperature. After purification an

oily orange compound was isolated. Analysis of the NMR data

revealed that clean conversion to Ti2 has taken place and

diphenylphosphine was formed as the byproduct (which explains

the oily consistency), verified by its characteristic NMR chemical

1

shifts (δ(³¹P{¹H}) = -40.8 ppm; δ(¹H) = 5.20 (d, J_P,H= 215.8 Hz,

1H, HPPh₂) ppm) (Scheme 4).

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O

Cl

O

Cl

+

H

Ti

P

n

rt

-hexane,

Ti1

L1

IV

Ti

"

O

C

CH₂

Cl

O

n

rt

-hexane,

-

HPPh₂

via:

Ti2

Cl

Ti

O

P

H

Figure 1. Molecular structure of Ti2. Hydrogen atoms (except H27A and

H27B) are omitted for clarity. Thermal ellipsoids are shown at the 50%

probability level. Selected bond lengths (Å) and angles (deg): Ti1–O1

1.9079(11), Ti1–Cl1 2.3690(5), O1–C26 1.3583(18), C11–C16 1.527(2), C16–

C26 1.540(2), C26–C27 1.334(2), Cl1–Ti1–O1 98.42(4), Ct1–Ti1–Ct2 135.1,

Σ∠C26 359.8 (Ct1 = centroid of C1–C5; Ct2 = centroid of C11–C15).

Scheme 4. Synthesis of Complex Ti2 via release of diphenylphospine.

In other words, the release of diphenylphosphine results in the

formal insertion of the smallest ketene moiety O=C=CH₂into the

Ti–C_exobond. Attempts of starting the reaction at -80 °C and/or

changing the solvent to THF or toluene also resulted in the

isolation of complex Ti2. In the high-field region, the ¹H NMR

spectrum of Ti2 shows the characteristic signals of the Cp^*

ligand at δ(¹H) = 1.81 ppm and the two signals for the

diastereotopic methylene group of the OC_q=CH₂unit at δ(¹H) =

4.19, 4.23 (δ(¹³C{¹H}) = 82.6 (OC_q=CH₂) and 181.3 (OC_q=CH₂)

ppm). The four signals for the chemical inequivalent hydrogen

atoms of the coordinated five-membered ring of the former

pentafulvene ligand at δ(¹H) = 5.19, 5.49, 5.62, and 6.60 ppm

and the chemical shift of the C_q,exoatom at δ(¹³C{¹H}) = 52.7 ppm

are all in good agreement to previously reported complexes.^[11]

Ti2 was also characterized by single-crystal X-ray diffraction;

Complex Ti2 crystallizes in the monoclinic space group P2₁/c.

The

molecular

structure

displays

the

expected

pseudotetrahedral coordination environment at the titanium

center (Cl1–Ti1–O1 98.42(2)°, Ct1–Ti1–Ct2 135.1°). The Ti1–

Cl1 bond length of 2.3690(5) Å and the Ti1–O1 bond length of

1.9079(11) Å are typical of single bonds.^[16,17]Compared to the

starting material Ti1 (C_exo–C_ipso1.422(4) Å^[9]) the C11–C16 bond

length of 1.527(2) is elongated and now constitutes a C(sp²)–

C(sp³) single bond.^[18]The newly formed C16–C26 bond with a

bond length of 1.540(2) Å is a typical C(sp³)–C(sp³) single

bond^[18]

, although for related complexes often significant

elongations of this bond are observed.^[11,12]

Surprisingly, the transfer of the reaction to the heavier

congeners zirconium and hafnium by using the previously

reported starting complexes Zr1 and Hf1^[8]yielded the desired

products Zr2 and Hf2 in overall good yields, but the synthesis of

suitable

crystals

were

obtained

from

a

saturated

n-hexane/toluene solution. The molecular structure of Ti2 is

shown in Figure 1.

Zr2 (δ(³¹P{¹H}) = 25.0 ppm) also yielded

a

byproduct

(δ(³¹P{¹H}) = -5.5 ppm) that could not be separated due to

solubility properties similar to those of Zr2^[15](Scheme 5).

O

Cl

O

Cl

+

M

P

n

rt

P

-hexane,

R

=

R

+

=

Zr, CR₂Ad;

=

R

p

-tolyl

:

=

:

=

Zr1

Hf1

L1

Zr2

Hf2

M

Zr, CR₂Ad

M

byproduct

=

Hf,

R

p

-tolyl

Hf,

Scheme 5. Synthesis of complexes Zr2 and Hf2.

The first assumption of the byproduct being the analogous

zirconium complex of Ti2 was ruled out because no

diphenylphosphine was formed during the reaction. Also, no

evidence for the other diastereoisomer was found, which is

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sometimes observed for related complexes^[11,12]and also in this

work (a discussion about the nature of the byproduct based on

the NMR data are summarized in the Supporting Information^[15]).

Multiple attempts to crystallize the byproduct out of the product

mixture failed, but crystals of Zr2 which were suitable for single-

crystal X-ray diffraction were obtained. The molecular structure

of Zr2 is shown in Figure 2.

Me

Hf

O

P

Cl

O

MeLi

THF,

Hf

P

rt

-

LiCl

Hf2

Hf3

Scheme 6. Synthesis of the methylated hafnium complex Hf3.

Hf3 was fully characterized by multinuclear NMR analyses^[15]

(δ(³¹P{¹H}) = -16.0 ppm). Furthermore the molecular structure of

Hf3 was determined by single-crystal X-ray diffraction and is

shown in Figure 3.

Figure 2. Molecular structure of Zr2. Hydrogen atoms, and phenyl groups of

the phosphine moiety are omitted for clarity. Thermal ellipsoids are shown at

the 50% probability level. Selected bond lengths (Å) and angles (deg): Zr1–O1

2.0018(9), Zr1–Cl1 2.48660(4), O1–C26 1.4280(15), P1–C26 1.9280(13),

C11–C16 1.5271(18), C16–C26 1.6448(18), C26–C27 1.5433(18), Cl1–Zr1–

O1 103.90(3), Ct1–Zr1–Ct2 133.1, Σ∠C26 (O1–C26–C27 + O1–C26–P1 +

P1–C26–C27) 320.2, Σ∠P1 312.0 (Ct1 = centroid of C1–C5; Ct2 = centroid of

C11–C15).

Figure 3. Molecular structure of Hf3. Hydrogen atoms, and phenyl groups of

the phosphine moiety are omitted for clarity. Thermal ellipsoids are shown at

the 50% probability level. Selected bond lengths (Å) and angles (deg): Hf1–O1

1.9744(7), Hf1–C45 2.2692(11), O1–C31 1.4275(12), P1–C31 1.9301(10),

C11–C16 1.5330(14), C16–C31 1.6387(14), C31–C32 1.5295(14), C45–Hf1–

O1 97.83(4), Ct1–Hf1–Ct2 134.3, Σ∠C31 (O1–C31–C32 + O1–C31–P1 + P1–

C31–C32) 319.6, Σ∠P1 312.1 (Ct1 = centroid of C1–C5; Ct2 = centroid of

C11–C15).

Zr2 crystallizes in the monoclinic space group P2₁/n and the

crystallographic features of this complex are all in the expected

ranges. The Zr1–Cl1, O1–C26, P1–C26, and C11–C26 bond

lengths constitute single bonds,^[16-18]although as mentioned

during the discussion of the structural data of Ti2, the newly

formed C–C bond C16–C26 (1.6448(18) Å) is remarkably

elongated, caused by the strong ring strain of the newly formed

σ,π chelate ligand^[19]and is comparable to those of extremely

long C–C single bonds.^[20]Despite this elongation, the former

carbonyl carbon atom is sp³-hybridized, as indicated by the sum

of angles around C26 (320.2°).

Subsequent methylation of a mixture of Zr2 and its byproduct

with methyllithium resulted in a complex mixture of products with

six different signals within the ³¹P{¹H} NMR^[15]. The hafnium

complex Hf2 reacts readily and cleanly with methyllithium to give

the corresponding methylated complex Hf3 (Scheme 6).

Complex Hf3 crystallizes in the triclinic space group P-1. The

crystallographic features of Hf3 are quite similar to those of

Zr2.^[16]The Hf1–C45 bond length of 2.2692(11) Å is in the

expected range for terminal hafnium–carbon single bonds.^[17]

The activation of Hf3 with the strong Lewis acid B(C₆F₅)₃to yield

its cationic counterpart resulted in a complex mixture of products.

The only phosphorus containing species which forms during the

reaction is diphenylphosphine (δ(³¹P{¹H}) = -40.8 ppm).^[15]

Additionally, the anion resulting of methyl abstraction

MeB(C₆F₅)₃^-could be identified by analysis of the NMR data, but

additional signals in the ¹¹B{¹H} NMR and ¹⁹F{¹H} NMR were

also detected.^[15]

Variations of the reaction conditions (different solvents, different

temperatures) resulted in similar results.

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Synthesis of Cationic Group 4 Metal Complexes with

Six-Membered M,O,C,C,C,P-units

Complexes Ti4, Zr4, Hf4, Ti5, Zr5, and Hf5 are only slightly

soluble in n-hexane and show good solubilities in benzene,

toluene, and tetrahydrofuran, providing ideal purification

purposes.

The molecular structures of complexes Ti4, Ti5, Zr4, and Hf5

were determined by single-crystal X-ray diffraction and are

shown in Figures 4 to 7 (the crystals were obtained either from

saturated n-hexane or toluene solutions).

Due to the difficulties concerning the synthesis of cationic d⁰

complexes with tridentate Cp,O,P-ligand frameworks, including a

four-membered M,O,C,P ring section, further studies were

focused on the synthesis of six-membered ring systems.

Yus and co-workers have previously described an elegant

synthesis of compound L2, featuring a diphenylphosphine and a

carbonyl functional group with two methylene groups as the

linker, which we identified as an ideal bidentate O,P-ligand

precursor for our attempted goal, and synthesized it according to

a slightly modified literature procedure (Scheme 7).^[21]

O

+

HPPh₂

P

neat,

-

rt,

0 °C

16

h

L2

,

69%

Scheme 7. Synthesis of the ligand precursor L2.

This

regioselective,

solvent-

methyl

and

vinyl

catalyst-free

Figure 4. Molecular structure of Ti4. Hydrogen atoms are omitted for clarity.

Thermal ellipsoids are shown at the 50% probability level. Selected bond

lengths (Å) and angles (deg): Ti1–O1 1.8501(9), Ti1–Cl1 2.3965(4), O1–C26

1.4259(14), P1–C29 1.8454(14), C11–C16 1.5233(16), C16–C26 1.6200(16),

C26–C27 1.5299(17), Cl1–Ti1–O1 101.09(3), Ct1–Ti1–Ct2 136.1, Σ∠C26

hydrophosphanation

diphenylphosphine yielded L2 as a colorless oil in 69% isolated

yield after column chromatography.

To our delight, the synthesis of the cationic complexes was

successful by employing the established three-step synthetic

pathway, starting from the monopentafulvene complexes Ti1,

Zr1, Hf1, and L2, providing each complex in good to very good

isolated yields (Scheme 8).

of

ketone

with

(O1–C26–C27

+ O1–C26–C28 + C27–C26–C28) 320.5, Σ∠P1 314.6

(Ct1 = centroid of C1–C5; Ct2 = centroid of C11–C15).

O

P

Cl

O

Cl

+

M

P

n

rt

-hexane,

R

:

=

:

=

Ti1

Zr1

Hf1

L2

Ti4

Zr4

Hf4

M

Ti, CR₂Ad

M

Ti, CR₂Ad; 88%

=

Zr, CR₂Ad

Zr, CR₂Ad; 42%

=

Hf,

R

p

-tolyl

Hf,

R

p-tolyl; 82%

rt

LiCl

THF,

MeLi

-

Ph

P

Ph

F₅

B(C₆

)

P

3

Me

O

M

Me

F₅

)

3

B(C₆

M

=

O

rt

toluene,

R

:

=

:

=

Ti6

Zr6

Hf6

Ti5

Zr5

Hf5

M

Ti, CR₂Ad; 82%

M

Ti, CR₂Ad; 82%

=

Zr, CR₂Ad; 91%

Figure 5. Molecular structure Zr4. Hydrogen atoms are omitted for clarity.

Thermal ellipsoids are shown at the 50% probability level. Selected bond

lengths (Å) and angles (deg): Zr1–O1 1.9586(5), Zr1–Cl1 2.4738(2), O1–C26

1.4260(9), P1–C29 1.8495(8), C11–C16 1.5312(10), C16–C26 1.6340(10),

C26–C27 1.5276(10), Cl1–Zr1–O1 97.83(4), Ct1–Zr1–Ct2 133.5, Σ∠C26 (O1–

=

R

p-tolyl;

Hf,

R

p-tolyl; 79%

Hf,

72%

Scheme 8. Three-step synthesis of cationic group 4 metal complexes Ti6, Zr6,

and Hf6 by reacting monopentafulvene complexes Ti1, Zr1, and Hf1 with L2,

subsequent methylation and final activation with B(C₆F₅)₃.

C26–C27

+

O1–C26–C28

+

C27–C26–C28) 320.9, Σ∠P1 304.6

(Ct1 = centroid of C1–C5; Ct2 = centroid of C11–C15).

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group 4.^[16]Shortly summarized, the M–Cl and terminal M–CH₃

bond lengths are typical of single bonds, and the M–O bond

lengths are shorter than typical single bonds between these

atoms, due to M(d_π)–O(p_π) interactions. The former carbonyl

C(sp³)–O distances of 1.42 Å on average are now typical of C–O

single bonds. Also, the remarkable elongation of the C–C bonds

C16–C26 (Ti4, Ti5, Zr4) and C16–C31 (Hf5) of above 1.63 Å

are present, together with the sp³-hybridizations of the former

carbonyl carbon atoms. The central metal atoms show

consistently distorted-tetrahedral coordination environments.

The NMR data of all compounds are consistent with the X-ray

structures. They are discussed for Ti4 as an example

Noteworthy, unlike the previously reported complexes^[11,12]each

was obtained as a diastereomerically pure compound.

The ³¹P{¹H} NMR chemical shift of Ti4 at δ(³¹P{¹H}) = -12.0 ppm

is only marginal shifted toward lower field in comparison to the

free ligand precursor L2, demonstrating same chemical

environments at the phosphorus atoms. In the high-field region

of the ¹H NMR spectrum at δ(¹H) = 1.39 ppm the methyl group of

the quaternary carbon atom of the former carbonyl group is

located with the corresponding ¹³C resonance at δ(¹³C{¹H}) =

31.0 ppm. The ¹³C NMR chemical shifts of the diastereotopic

methylene groups of the OC_qCH₂CH₂PPh₂moiety at δ(¹³C{¹H}) =

22.8 and 35.8 ppm show characteristic doublet coupling

Figure 6. Molecular structure of Ti5. Hydrogen atoms are omitted for clarity.

Thermal ellipsoids are shown at the 50% probability level. Selected bond

lengths (Å) and angles (deg): Ti1–O1 1.8521(10), Ti1–C49 2.1876(15), O1–

C26 1.4247(17), P1–C29 1.8479(15), C11–C16 1.5259(19), C16–C26

1.6259(19), C26–C27 1.5274(19), C49–Ti1–O1 97.93(5), Ct1–Ti1–Ct2 135.1,

Σ∠C26 (O1–C26–C27 + O1–C26–C28 + C27–C26–C28) 321.0, Σ∠P1 303.5

(Ct1 = centroid of C1–C5; Ct2 = centroid of C11–C15).

1

2

constants of J_C,P= 11.6 Hz and J_C,P= 20.7 Hz, respectively.

Highly diagnostic is the ¹³C chemical shift of the exocyclic

carbon atom at δ(¹³C{¹H}) = 54.7 ppm, which is significantly

shifted toward higher field compared to starting complex Ti1.^[9]

Four signals each for the C₅H₄group are found in the ¹H and ¹³

C

NMR spectra, ranging from δ(¹H) = 5.04 to 6.42 ppm and

δ(¹³C{¹H}) = 104.5 to 120.1 ppm. These and the chemical shifts

of the Cp^*and PPh₂moieties are in the same characteristic

ranges as for the previously reported complexes with the

OC_qCH₂PPh₂functionality.^[11,12]

Activation of the methylated complexes Ti5, Zr5, and Hf5 with

the highly Lewis acidic borane B(C₆F₅)₃in toluene at room

temperature yielded the corresponding cationic group 4 metal

complexes Ti6, Zr6, and Hf6 as orange (Ti6) and colorless (Zr6,

Hf6) solids, diastereomerically pure, and in yields of up to 91%

after purification with the weakly coordinating borate anion

-

MeB(C₆F₅)₃. As the result of the methyl group abstraction, the

phosphorus coordinates to the metal center and the tridentate

Cp,O,P-ligand frameworks are formed. These compounds are

stable in the solid state, and, like their precursor complexes, can

be stored for months under inert conditions without any

decomposition.

The cationic complexes are insoluble in aliphatic hydrocarbons

(e.g. n-pentane or n-hexane) and only marginally soluble in

aromatic solvents such as benzene or toluene, which already

indicates the formation of ionic species. Therefore NMR data

were collected in deuterated dichloromethane, in which Ti6, Zr6,

and Hf6 proved to be stable. The NMR data for all compounds is

Figure 7. Molecular structure Hf5. Hydrogen atoms are omitted for clarity.

Thermal ellipsoids are shown at the 50% probability level. Selected bond

lengths (Å) and angles (deg): Hf1–O1 1.976(4), Hf1–C47 2.264(7), O1–C31

1.407(8), P1–C33 1.853(7), C11–C16 1.538(9), C16–C31 1.635(9), C31–C34

1.530(9), C47–Hf1–O1 99.2(2), Ct1–Hf1–Ct2 134.8, Σ∠C31 (O1–C31–C32 +

O1–C31–C34 + C32–C31–C34) 324.3, Σ∠P1 302.5 (Ct1 = centroid of C1–C5;

Ct2 = centroid of C11–C15).

summarized

in

table

1.

Ti4, Ti5, Zr4, and Hf5 all crystallize in monoclinic space groups,

either P2₁/n (Ti4), P2₁/c (Ti5, Zr4), or P2₁(Hf5). With regard to

the crystallographic features of these complexes, expected

similarities are found, and differences in the bond lengths and

angles follow the tendency of increasing atomic radii within

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European Journal of Inorganic Chemistry

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Table 1. Selected NMR parameters of complexes Ti4-9, Zr4-6, and Hf4-6^[a]

Compd.

.

δ¹³C{¹H}

δ¹H / δ¹³C{¹H}

δ¹³C{¹H}

δ¹H / δ¹³C{¹H}

OC_qCH₃

δ¹³C{¹H}

δ ³¹P{¹H}

-12.0

-12.3

-13.9

-12.7

-12.9

-14.0

28.6

PCH₂CH₂

MCH₃/BCH₃

OC_q

C_q,exo/C_q,ipso

ⁿJ_C,P(PCH₂CH₂)

22.8 / 35.8

¹J_C,P= 11.6

²J_C,P= 20.7

22.8 / 36.7

¹J_C,P= 11.5

²J_C,P= 20.2

24.0 / 39.2

¹J_C,P= 11.3

²J_C,P= 19.4

22.6 / 36.6

¹J_C,P= 10.8

²J_C,P= 19.8

22.8 / 37.6

¹J_C,P= 11.3

²J_C,P= 20.0

24.1 / 38.9

¹J_C,P= 10.7

²J_C,P= n.o.

28.7 / 39.1

¹J_C,P= 28.7

²J_C,P= 48.1

25.1^[b]/35.7

¹J_C,P= n.o.

²J_C,P= n.o.

22.6 / 37.4

¹J_C,P= 23.1

²J_C,P= n.o.

-

³J_C,P(OC_q)

111.7

³J_C,P= 13.9

Ti4^[d]

-

1.39 / 31.0

1.41 / 31.1

1.53 / 29.8

1.32 / 30.8

1.36 / 31.0

1.31 / 30.4

1.70 / 34.3

1.67 / 36.2

1.86 / 32.2

54.7 / 156.7

55.1 / 154.9

65.9 / 147.4

54.9 / 151.4

55.3 / 150.3

66.1 / 143.9

55.0 / 155.6

55.8 / 155.5

66.1 / 150.8

Zr4^[d]

Hf4^[d]

Ti5^[d]

-

106.9

³J_C,P= 13.3

-

105.4

³J_C,P= 13.7

0.26 / 35.3

-0.07 / 23.0

-0.08 / 27.8

0.48 / 12.8^[b]

0.49 /11.9^[b]

0.51 / 10.0^[b]

107.4

³J_C,P= 12.9

Zr5^[d]

Hf5^[d]

104.3

³J_C,P= 13.0

103.4

³J_C,P= 13.2

Ti6^[d]

*

113.9

³J_C,P= n.o.

Zr6^[d]

*

109.5

³J_C,P= n.o.

14.4

Hf6^[c]

106.4

³J_C,P= n.o.

16.6

Ti7^[c],[e]

Ti8^[e]

-

115.9

³J_C,P= 3.3

114.6

2.27 / 28.8

2.24 / 32.7

2.09 / 35.4

57.0 / 154.0

58.1 / 149.4

57.6 / 157.0

-4.0

-3.6

41.4

-

0.62 / 35.0

0.49 / 9.7^[b]

³J_C,P= 2.8

Ti9^[e]

*

117.5

³J_C,P= n.o.

[a] Values are given in ppm and J values in Hz. Measurements were carried out in C₆D₆or CD₂Cl₂(marked with an asterisk) [b] assignment by

¹H/¹³C-HMQC spectra [c] only one signal given (1:1 mixture of diastereoisomers) [d] diphenylphosphine moieties, two methylene groups as the

linker between OC_qand PPh₂[e] diphenylphosphine moieties, aryl linker between OC_qand PPh₂

shift of 44.4 ppm in the ³¹P{¹H} NMR due to the coordination of

All chemical shifts in the ¹H and ¹³C NMR spectra of the cationic

complexes are in the expected range, also showing the

expected characteristic coupling patterns for the nuclei close to

the phosphorus (Table 1). The ³¹P{¹H} resonances are shifted

toward lower field, depending on the metal to a different extent,

when compared to their methylated precursor complexes

(Δδ³¹P{¹H} = 41.3 (Ti5/Ti6), 27.3 (Zr5/Zr6), 30.6 (Hf5/Hf6) ppm).

This indicates interactions between the Lewis basic phosphine

groups and the Lewis acidic metal centers. For example, the

cationic zirconium complex [Cp₂ZrOC₆H₄P(^tBu₂)]⁺[B(C₆F₅)₄]^-I,

prepared by Wass et al., starting from the methylated precursor

complex and the trityl salt [Ph₃C]⁺[B(C₆F₅)₄]^-, showed a downfield

the phosphorus to the metal center.^[7]Similar downfield shifts

were observed for the cationic complexes reported previously by

our group^[11], so that, in conclusion, the elongation of the O,P-

subunit by one methylene group does not prevent coordination

of the phosphorus to the metal center.

The NMR data clearly indicate the abstraction of the methyl

group and the formation of the borate anion MeB(C₆F₅)₃^-in all

cases (e.g. for Ti6: δ(¹¹B{¹H}) = -15.5 ppm; δ(¹⁹F{¹H}) = -167.9

(m-F_ArB),

-165.3

(p-F_ArB),

-133.1

(o-F_ArB)

ppm;

δ(¹H/¹³C{¹H}(BCH₃)) = 0.48/12.8 ppm). The Δδ(m,p-F) parameter

introduced by Horton and co-workers to determine whether this

anion shows a coordination to the d⁰metal centers in solution or

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-

not, verify that the MeB(C₆F₅)₃anions are noncoordinating in Ti6, In addition, we were able to determine the molecular structures

Zr6, and Hf6.^[22,23]The Δδ(m,p-F) values of Ti6 (2.6 ppm), Zr6

(2.5 ppm), and Hf6 (2.6 ppm) are in good accordance to other

of Ti7 and Ti8 by single-crystal X-ray diffraction, which are

shown in Figures 8 and 9.

-

characterized cationic complexes, in which the MeB(C₆F₅)₃

anion is noncoordinating, e.g. Δδ(m,p-F) = 2.6 ppm for the

activation product of Cp₂Zr(Me)OC_q(Fc)PCy₂, B(C₆F₅)₃and

[Pd(C₃H₅)Cl]₂.^[24]Furthermore, the M⁺signals of Ti6, Zr6, and

Hf6 were detected by high-resolution ESI mass spectrometry.

For further derivatization of the ligand-framework, we also

wanted to test the potential of introducing an aryl linker between

the oxygen and phosphorus donor sides and rest whether this

leads to a metal phosphorus interaction or not. Therefore Ti1

was reacted with the appropriate ligand precursor L3, which we

synthesized according to a literature procedure.^[25]Following the

established three-step reaction pathway of insertion, subsequent

methylation and final activation with B(C₆F₅)₃, the cationic

titanium complex Ti9 and its parent complexes Ti7 (1:1 mixture

of diastereoisomers) and Ti8 were obtained in isolated yields

between 80 and 93% (Scheme 9).

Figure 8. Molecular structure of Ti7. Hydrogen atoms, and the phenyl groups

of the phosphine moieties are omitted for clarity. Thermal ellipsoids are shown

at the 50% probability level. Selected bond lengths (Å) and angles (deg): Ti1–

O1 1.8459(10), Ti1–Cl1 2.4099(5), O1–C26 1.4353(17), P1–C29 1.8555(14),

C11–C16 1.5222(19), C16–C26 1.6486(19), C26–C27 1.5335(19), Cl1–Ti1–

O1 96.88(3), Ti1–O1–C26 137.40(9), Ct1–Ti1–Ct2 134.1, Σ∠C26 (O1–C26–

C27 + O1–C26–C28 + C27–C26–C28) 320.9, Σ∠P1 304.6 (Ct1 = centroid of

C1–C5; Ct2 = centroid of C11–C15).

Ph₂

P

O

Cl

O

+

P

Ti

n

rt

-hexane,

Ti1

L3

Ti7

80%

;

rt

LiCl

THF,

MeLi

-

Ph₂

P

Ph₂

P

F₅

B(C₆

)

Me

O

3

Me

F₅

)

3

Ti

B(C₆

O

rt

toluene,

Ti9

Ti8

93%

;

89%

;

Scheme 9. Three-step synthesis of cationic titanium complex Ti9 with an aryl

linker between the oxygen and phosphorus donor sites.

Compounds Ti7, Ti8, and Ti9 were thoroughly characterized by

multinuclear NMR spectroscopy (most characteristic signals are

summarized in Table 1) and the data agree well with the other

cationic group 4 complexes derived from bidentate O,P-ligand

precursors and monopentafulvene complexes.^[11]

Figure 9. Molecular structure Ti8. Hydrogen atoms, and the phenyl groups of

the phosphine moieties are omitted for clarity. Thermal ellipsoids are shown at

the 50% probability level. Selected bond lengths (Å) and angles (deg): Ti1–O1

1.8501(11), Ti1–C46 2.2005(17), O1–C26 1.4301(18), P1–C29 1.8518(16),

C11–C16 1.525(2), C16–C26 1.652(2), C26–C27 1.531(2), C46–Ti1–O1

95.84(6), Ti1–O1–C26 136.52(9), Ct1–Ti1–Ct2 134.9, Σ∠C26 (O1–C26–C27

+ O1–C26–C28 + C27–C26–C28) 321.1, Σ∠P1 304.9 (Ct1 = centroid of C1–

C5; Ct2 = centroid of C11–C15).

Most importantly, complex Ti9 also shows

a persistent

connection between the Lewis acidic metal center and the Lewis

basic phosphine moiety as evidenced by ³¹P{¹H} NMR

spectroscopy (Δδ(³¹P{¹H}(Ti8/Ti9) = 45 ppm shift toward lower

-

field). The MeB(C₆F₅)₃anion is noncoordinating (Δδ(m,p-F) =

2.6 ppm) and the M⁺signal of Ti9 was detected by high-

resolution ESI mass spectrometry.

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dried under high vacuum before use. The methyllithium was used as a

1.6 M solution in diethyl ether, and the n-butyllithium was used as a

1.6 M solution in n-hexane. Potassium diphenylphosphide was used as a

0.5 M solution in tetrahydrofuran. The pentafulvene complexes Ti1, Zr1

and Hf1 were synthesized according to literature procedures.^[8,9]Methyl

vinyl ketone, acetyl chloride, 2-fluoroacetophenone, and diphenyl

The structural data are in the same range as for the

comprehensively discussed structures above, so that a more

detailed discussion is omitted at this point.

Conclusions

phosphine

were

purchased

from

commercial

sources.

2-Fluoroacetophenone was used as received. Methyl vinyl ketone, acetyl

chloride, and diphenyl phosphine were distilled over CaCl₂or CaH₂,

freeze-pump-thaw degassed three times prior to use, and stored under

nitrogen. Thin-layer chromatography was performed using commercial

available Alugram SIL/G UV₂₅₄sheets with fluorescent indicator (254 nm)

from Macherey-Nagel. Silica gel from Grace (particle size = 40-63 µm)

was used for column chromatography. High-resolution mass spectra

were measured on a Finnigan-MAT95 spectrometer using ESI. Infrared

spectra were performed on a Bruker Tensor 27 spectrometer with a MKII

Reflection Golden Gate Single Diamond ATR system. NMR spectra were

recorded on Bruker Avance 300, Bruker Avance 500, and Bruker Avance

III 500 spectrometers. ¹H NMR spectra were referenced to the residual

solvent resonance as internal standard (benzene-d₆(C₆D₆): δ¹H(C₆D₅H)

= 7.16 ppm, dichloromethane-d₂(CD₂Cl₂): δ¹H(CDHCl₂) = 5.32 ppm) and

¹³C{¹H} spectra were referenced by using the central line of the solvent

In conclusion, we have presented the possibilities to modify the

ancillary Cp,O,P-ligand framework of cationic group

4

complexes by employing a synthetic pathway of forming this

tridentate ligand framework directly in the coordination sphere of

the corresponding metal. Attempts to synthesize four-membered

titanacycles within the ligand system proved to yield different

products, mostly dependent on the nature of the metal. For

titanium, the reaction of the starting complex Ti1 with

acetyldiphenylphosphine (L1) selectively results in the release of

diphenylphosphine after the insertion reaction, forming complex

Ti2, which is the product of the formal insertion of the carbonyl

group of the smallest ketene (H₂C=C=O) into the Ti–C_exobond.

The zirconium congener Zr1 reacts with L1, without the loss of

diphenylphosphine to obtain Zr2, but this reaction is

accompanied by the formation of a side product, which is

assumingly a dimeric zirconium complex. The subsequent

methylation of the product mixture showed the existence of a

broad spectrum of products. In contrast, the hafnium complex

Hf1 as the initial point yielded both, the product Hf2 of the

insertion reaction and the subsequent methylation product Hf3 in

a selective manner. The attempted final activation with B(C₆F₅)₃

causes decomposition of the complex accompanied by release

of diphenylphosphine. The use of monopentafulvene complexes

Ti1, Zr1, and Hf1 together with the readily accessible bidentate

O,P-ligand precursor L2 with two methylene groups as the

linking moiety between the carbonyl functional group and the

phosphine donor side, yielded the corresponding cationic

complexes Ti6, Zr6, and Hf6 in an efficient three-step synthetic

protocol in good to excellent yields under mild reaction

conditions. In addition, we have demonstrated, that an aryl

group can successfully be introduced between the oxygen and

the phosphorus starting from Ti1 and the appropriate P,O-ligand

precursor L3. As a consequence, the cationic group 4 metal

complexes Ti6, Zr6, Hf6, and Ti9 feature six-membered

titanacycles because of a persistent interaction between the

Lewis acidic metal center and the Lewis basic phosphine moiety.

Further work in our group will focus on reactivity studies on the

variety of cationic group 4 metal complexes reported herein and

elsewhere with regard to tm-FLP chemistry.

signal (benzene-d₆(C₆D₆): δ¹³C{¹H}(C₆D₆)

=

128.06 ppm,

dichloromethane-d₂(CD₂Cl₂): δ¹³C{¹H}(CD₂Cl₂) = 53.84 ppm). ¹¹B{¹H}

NMR, ¹⁹F{¹H} NMR, and ³¹P{¹H} NMR spectra were referenced against

external standards (BF₃•OEt₂(δ¹¹B{¹H}(BF₃•OEt₂) = 0.0 ppm; CFCl₃

(δ¹⁹F{¹H}(CFCl₃) = 0.0 ppm); H₃PO₄(δ³¹P{¹H}(H₃PO₄) = 0.0 ppm).

Elemental analyses were carried out on a EuroEA 3000 Elemental

Analyzer. The carbon value in the elemental analysis is often lowered by

carbide formation. The hydrogen value is found in some cases higher,

due to residual traces of solvents. Although in some cases satisfactory

elemental analysis could not be obtained, the data is included to

demonstrate the best results to date. The combustion analysis of group 4

organometallics is known to be difficult.^[26]Melting points were

determined using

Cambridge, U.K..

a “Mel-Temp” apparatus by Laboratory Devices,

Synthesis of L1: Compound L1 was synthesized according to a slightly

modified literature procedure.^[14]To a solution of diphenylphosphine

(2.3 mL, 13.43 mmol) and triethylamine (1.9 mL, 13.43 mmol) in 30 mL of

diethyl ether, acetyl chloride (1.0 mL, 13.43 mmol) was added slowly,

resulting in a colorless precipitate. The reaction mixture was stirred for 2

h at room temperature, followed by filtration of the suspension through

celite and washing of the precipitate with diethyl ether (3×10 mL).

Evaporation of all volatiles yielded L1 as a colorless oil. Yield: 2.696 g

(11.81 mmol, 88%). ¹H NMR (500 MHz, C₆D₆, 305 K): δ = 1.92 (d, 3H,

³J_P,H= 6.1 Hz, CH₃), 7.00-7.07 (m, 6H, 4×o-CH_PhP, 2×p-CH_PhP), 7.43-

7.47 (m, 4H, 4×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 305 K): δ

2

= 32.5 (d, J_C,P= 39.6 Hz, CH₃), 128.9 (d, J_C,P= 7.5 Hz, 4×o-CH_PhP),

1

129.6 (2×p-CH_PhP), 133.5 (d, J_C,P

= 7.6 Hz, C_q,PhP), 135.0 (d,

³J_C,P= 18.3 Hz, 4×m-CH_PhP), 219.1 (d, J_C,P= 38.9 Hz, C=O) ppm.

1

³¹P{¹H} NMR (202 MHz, C₆D₆, 305 K): δ = 17.0 ppm.

Synthesis of L2: Compound L2 was synthesized according to a slightly

modified literature procedure.^[21]Methyl vinyl ketone (1.5 mL,

17.76 mmol) was added slowly to diphenylphosphine (3.1 mL,

17.76 mmol) at 0 °C. The reaction mixture was stirred for 16 h at room

temperature. The crude product was purified by column chromatography

(SiO₂; PE:EE). The product L2 was obtained as a colorless liquid. Yield:

3.121 g (12.18 mmol, 69%). R_f= 0.54 (SiO₂; PE:EE = 6:1). ¹H NMR

(500 MHz, C₆D₆, 300 K): δ = 1.49 (s, 3H, CH₃), 2.10-2.15 (m, 2H,

PCH₂CH₂), 2.26-2.29 (m, 2H, PCH₂CH₂), 7.04-7.10 (m, 6H, 6×CH_Ph),

7.38-7.41 (m, 4H, 4×CH_Ph) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 300 K): δ

= 21.9 (d, ¹J_C,P= 11.7 Hz, PCH₂CH₂), 29.1 (CH₃), 39.6 (d, ²J_C,P= 18.2 Hz,

Experimental Section

All air- and moisture-sensitive reactions were carried out under an inert

atmosphere of argon or nitrogen with rigorous exclusion of oxygen and

moisture using standard glovebox and Schlenk techniques. The glass

equipment was stored in an oven at 120 °C and evacuated prior to use.

Solvents and liquid educts were dried according to standard procedures

and/or freeze-pump-thaw degassed three times prior to use. Solvents

were distilled over Na/K alloy and benzophenone or CaH₂under nitrogen

atmosphere. Solid materials were stored and weighed in a glovebox or

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2

PCH₂CH₂), 128.8 (d, J_C,P= 7.3 Hz, 4×o-CH_PhP), 128.9 (2×p-CH_PhP),

(δ³¹P{¹H} = -5.5 ppm; byproduct). Yield: 0.842 g (mixture of Zr2 +

byproduct). ¹H NMR (500 MHz, C₆D₆, 300 K): δ = 1.85 (s, 15H, C₅Me₅),

1.90 (d, ³J_P,H= 12.7 Hz, OC_qCH₃), 5.46-5.47 (m, 1H, C₅H₄), 5.57-5.58 (m,

1H, C₅H₄), 5.83-5.84 (m, 1H, C₅H₄), 6.41-6.42 (m, 1H, C₅H₄) ppm.

³¹P{¹H} NMR (202 MHz, C₆D₆, 300 K): δ = 25.0 ppm.

3

1

133.1 (d, J_C,P= 18.8 Hz, 4×m-CH_PhP), 139.2 (d, J_C,P= 14.3 Hz,

2×C_q,PhP), 205.1 (d, J_C,P= 12.4 Hz, C=O) ppm. ³¹P{¹H} NMR (202 MHz,

C₆D₆, 300 K): δ = -15.5 ppm.

3

Synthesis of L3: Compound L3 was synthesized according to a slightly

modified literature procedure.^[24]To

a

solution of potassium

Synthesis of Hf2: In a glove box compound L1 (0.188 g, 0.823 mmol) in

n-hexane (3×5 mL) was added to a solution of complex Hf1 (0.500 g,

0.823 mmol) in 10 mL of n-hexane. The suspension was stirred for 16 h

at room temperature resulting in a colorless suspension. All volatiles

were removed under vacuum to yield Hf2 a colorless solid. Yield: 0.481 g

(0.576 mmol, 70%). Melting point: 216-218 °C (dec.). IR (ATR): � = 2951,

2915, 2861, 1511, 1478, 1454, 1433, 1375, 1092, 1061, 1024, 923, 890,

867, 856, 831, 816, 798, 752, 739, 700, 664, 639, 601 cm^-1. ¹H NMR

(500 MHz, C₆D₆, 305 K): δ = 2.02 (s, 15H, C₅Me₅), 2.04 (s, 3H, CH_3,p-tolyl),

2.25 (s, 3H, CH_3,p-tolyl), 2.32 (d, ³J_P,H= 2.6 Hz, 3H, OC_qCH₃), 5.44-5.46 (m,

1H, C₅H₄), 5.52-5.54 (m, 1H, C₅H₄), 5.66-5.68 (m, 1H, C₅H₄), 6.19-6.21

(m, 1H, CH_Aryl), 6.60-6.62 (m, 1H, CH_Aryl), 6.68-6.70 (m, 1H, C₅H₄), 6.85-

6.87 (m, 1H, CH_Aryl), 6.96-7.08 (m, 7H, 7×CH_Aryl), 7.14-7.17 (m, 2H,

2×CH_Aryl)*, 7.25-7.32 (m, 4H, 4×CH_Aryl), 7.82-7.85 (m, 2H, 2×CH_Aryl) ppm.

* = overlap with C₆D₆signal. ³¹P{¹H} NMR (202 MHz, C₆D₆, 300 K): δ =

16.3 ppm. note: ¹³C{¹H} NMR measurements only showed low intensities

of the signals due to poor solubility.

diphenylphosphide (21.4 mL, 10.70 mmol; 0.5 M in THF) at reflux, was

added a solution of 2-fluoroacetophenone (1.3 mL, 10.70 mmol) in THF.

The resulting yellow suspension was stirred for 30 minutes at reflux,

followed by addition of 50 mL of water and 50 mL of dichloromethane.

The organic layer was collected and the aqueous phase was extracted

with 2×50 mL of dichloromethane. The crude product was purified by

column chromatography (SiO₂; DCM). The product L2 was obtained as a

yellow solid. Yield: 0.631 g (2.073 mmol, 19%). R_f= 0.56 (SiO₂; DCM).

¹H NMR (500 MHz, C₆D₆, 300 K): δ = 2.03 (d, 3H,

6.91-6.95 (m, 2H, 2×C₆H₄), 7.05-7.10 (m, 6H, 4× o-CH_PhP, 2×p-CH_PhP),

7.20-7.22 (m, 1H, C₆H₄), 7.33-7.35 (m, 1H, C₆H₄), 7.41-7.45 (m, 4H,

4×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 300 K): δ = 27.4 (CH₃),

TS

J

= 1.6 Hz, CH₃),

P,H

2

128.0 (C₆H₄)*, 128.6 (2×p-CH_PhP), 128.7 (d, J_C,P= 7.0 Hz, 4×o-CH_PhP),

130.3 (d, ²J_C,P= 2.5 Hz, o-C₆H₄P), 131.6 (C₆H₄), 134.4 (d, ³J_C,P= 20.7 Hz,

4×m-CH_PhP), 135.2 (C₆H₄), 139.6 (d, ¹J_C,P= 11.8 Hz, 2×C_q,PhP), 140.9 (d,

J

_C,P= 29.1 Hz, C_q,C6H4C=O), 141.7 (d, J_C,P= 17.2 Hz, C_q,C6H4P), 197.4

(C=O) ppm. * = overlap with C₆D₆signal. ³¹P{¹H} NMR (202 MHz, C₆D₆,

300 K): δ = -2.5 ppm.

Synthesis of Hf3: To a solution of complex Hf2 (0.250 g, 0.299 mmol) in

10 mL of tetrahydrofuran was added a methyl lithium solution (0.2 mL,

0.299 mmol; 1.6 M in diethyl ether). The reaction mixture was stirred for

16 h at room temperature. The solvent was completely removed under

vacuum, and the residue was dissolved in 8 mL of toluene. The solution

was filtered, and the residue was washed with toluene (2×5 mL). All

volatiles were removed under vacuum to give complex Hf3 as a colorless

solid. Crystals suitable for single crystal X-ray diffraction were obtained

from an n-hexane solution at -26 °C. Yield: 0.186 g (0.228 mmol, 76%).

Melting point: 202-204 °C (dec.). IR (ATR): � = 3040, 2994, 2944, 2916,

2871, 1584, 1476, 1428, 1368, 1196, 1149, 1095, 1059, 1024, 923, 889,

870, 857, 811, 797, 751, 740, 697 cm^-1. ¹H NMR (500 MHz, C₆D₆,

305 K): δ = 0.11 (s, 3H, HfCH₃), 1.93 (s, 15H, C₅Me₅), 2.06 (s, 3H,

Synthesis of Ti2: In a glove box compound L1 (0.383 g, 1.679 mmol) in

n-hexane (3×5 mL) was added to a solution of complex Ti1 (0.700 g,

1.679 mmol) in 10 mL of n-hexane. The suspension was stirred for 16 h

at room temperature resulting in a yellow suspension. All volatiles were

removed under vacuum to yield an oily orange mixture of complex Ti2

and HPPh₂. Crystals suitable for single crystal X-ray diffraction of

complex Ti2 were obtained from a n-hexane/toluene (5:1) solution at -

4 °C. Additionally, NMR data of crystalline Ti2 were collected. Yield:

0.992 g (mixture of Ti2 and HPPh₂). ¹H NMR (500 MHz, C₆D₆, 300 K): δ

= 1.52-1.71 (m, 7H, CH_Ad/CH_2,Ad), 1.75-1.79 (m, 2H, CH_Ad/CH_2,Ad), 1.81

(s, 15H, C₅Me₅), 1.84-1.88 (m, 1H, CH_Ad/CH_2,Ad), 2.36-2.44 (m, 3H,

CH_Ad/CH_2,Ad), 2.67-2.70 (m, 1H, CH_Ad/CH_2,Ad), 4.19 (s, 1H, OCq=CH2),

4.23 (s, 1H, OC_q=CH₂), 5.18-5.19 (m, 1H, C₅H₄), 5.48-5.50 (m, 1H, C₅H₄),

5.61-5.63 (m, 1H, C₅H₄), 6.59-6.61 (m, 1H, C₅H₄) ppm. HPh₂: δ = 5.20 (d,

¹J_P,H= 215.8 Hz, HPPh₂), 7.01-7.02 (m, 6H, 2×p-CH_PhP, 4×o-CH_PhP),

7.35-7.38 (m, 4H, 4×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 300

K): δ = 12.6 (C₅Me₅), 28.0 (CH_Ad), 28.4 (CH_Ad), 31.8 (CH_Ad), 33.9 (CH_2,Ad),

34.1 (CH_2,Ad), 35.0 (CH_Ad), 35.02 (CH_2,Ad), 36.8 (CH_2,Ad), 38.8 (CH_2,Ad),

52.7 (C_q,exo), 82.6 (OC_q=CH₂), 107.0 (C₅H₄), 113.7 (C₅H₄), 115.6 (C₅H₄),

123.3 (C₅H₄), 125.4 (C₅Me₅), 148.4 (C_q,ipso), 181.3 (OC_q=CH₂) ppm.

3

CH_3,p-tolyl), 2.07 (d, J_P,H= 3.2 Hz, 3H, OC_qCH₃), 2.25 (s, 3H, CH_3,p-tolyl),

5.07-5.08 (m, 1H, C₅H₄), 5.45-5.47 (m, 1H, C₅H₄), 5.59-5.61 (m, 1H,

C₅H₄), 6.39-6.41 (m, 1H, CH_p-tolyl), 6.52-6.53 (m, 1H, C₅H₄), 6.66-6.68 (m,

1H, CH_p-tolyl), 6.91-6.93 (m, 1H, CH_p-tolyl), 6.96-7.14 (m, 10H, 10×CH_Aryl),

7.31-7.34 (m, 2H, 2×m-CH_PhP), 7.48-7.50 (m, 1H, CH_p-tolyl), 7.78-7.81 (m,

2H, 2×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 305 K): δ = 11.7

(C₅Me₅), 20.8 (CH_3,p-tolyl), 21.2 (CH_3,p-tolyl), 27.7 (OC_qCH₃), 28.4 (HfCH₃),

69.1 (d, ²J_C,P= 20.7 Hz, C_q,exo), 106.2 (C₅H₄), 109.2 (C₅H₄), 110.0 (C₅H₄),

1

111.5 (d, J_C,P= 20.2 Hz, OC_qCH₃), 115.4 (C₅H₄), 117.6 (C₅Me₅), 126.9

2

HPPh₂: δ = 128.6 (2×p-CH_PhP), 128.8 (d, J_C,P= 6.2 Hz, 4×o-CH_PhP),

(2×o-CH_p-tolylCH₃), 127.8 (d, ²J_C,P= 4.1 Hz, 2×o-CH_PhP), 128.1

3

1

134.3 (d, J_C,P= 17.0 Hz, 4×m-CH_PhP), 135.4 (d, J_C,P= 10.8 Hz,

2×C_q,PhP) ppm. ³¹P{¹H} NMR (202 MHz, C₆D₆, 300 K): δ = -40.8 (HPPh₂)

ppm. HR/MS calculated: m/z = 455.2430 [M-Cl^-+MeOH]; measured (ESI):

m/z = 455.2425.

(2×o-CH_p-tolylCH₃), 128.4 (p-CH_PhP), 128.5 (d, ²J_C,P= 8.1 Hz, 2×o-CH_PhP),

4

129.4 (p-CH_PhP), 132.5 (d, J_C,P

= 5.6 Hz, 2×m-CH_p-tolylCH₃), 132.9

3

(2×m-CH_p-tolylCH₃), 135.0 (d, J_C,P= 16.7 Hz, 2×m-CH_PhP), 135.7

(C_q,p-tolylCH₃), 136.6 (C_q,p-tolylCH₃), 137.5 (d, J_C,P= 22.7 Hz, 2×m-CH_PhP),

3

1

140.0 (d, J_C,P= 28.7 Hz, C_q,PhP), 141.18 (p-C_q,p-tolylCH₃), 141.2 (d,

¹J_C,P= 26.8 Hz, C_q,PhP), 142.5 (d, J_C,P= 7.3 Hz, p-C_q,p-tolylCH₃), 145.7

3

Synthesis of Zr2: In a glove box compound L1 (0.332 g, 1.456 mmol) in

n-hexane (3×5 mL) was added to a solution of complex Zr1 (0.670 g,

1.456 mmol) in 10 mL of n-hexane. The suspension was stirred for 16 h

at room temperature resulting in a colorless suspension. All volatiles

were removed under vacuum to yield a colorless solid, identified as a

mixture of complex Zr2 and an additional byproduct (ratio 3:1). Crystals

suitable for single crystal X-ray diffraction of complex Zr2 were obtained

from an n-hexane/toluene (4:1) solution at -4 °C. Only the clearly

assignable signals of Zr2 are given in the analyses of the NMR data. We

suppose, that the byproduct is some kind of dimeric species due to eight

(C_q,ipso) ppm. ³¹P{¹H} NMR (202 MHz, C₆D₆, 305 K): δ = 16.0 ppm.

HR/MS calculated: m/z = 815.2908 [M-H⁺]; measured (ESI): m/z =

815.2905.

Synthesis of Ti4: In a glove box compound L2 (0.500 g, 1.951 mmol) in

n-hexane (3×5 mL) was added to a solution of complex Ti1 (0.813 g,

1.951 mmol) in 10 mL of n-hexane. The suspension was stirred for 16 h

at room temperature resulting in a yellow suspension. The supernatant

was decanted, the residue was washed with n-hexane (3×5 mL) and

dried under vacuum to yield Ti4 as a yellow solid. Crystals suitable for

single crystal X-ray diffraction of complex Ti4 were obtained from a

additional C₅H₄signals in the ¹H NMR. Two other signals in the H NMR

might be assigned to two other pentamethylcyclopentadienyl groups

1

10.1002/ejic.201801016

European Journal of Inorganic Chemistry

FULL PAPER

saturated n-hexane solution at room temperature. Yield: 1.156 g

(1.717 mmol, 88%). Melting point: 178-180 °C. IR (ATR): � = 3079, 3017,

2955, 2899, 2854, 1480, 1461, 1452, 1434, 1414, 1384, 1366, 1333,

1315, 1262, 1213, 1201, 1173, 1149, 1096, 1062, 1025, 1000, 952, 917,

886, 874, 848, 832, 743, 694, 675, 658, 635, 565 cm^-1. ¹H NMR

(500 MHz, C₆D₆, 299 K): δ = 1.28-1.35 (m, 2H, PCH₂), 1.39 (s, 3H,

OC_qCH₃), 1.48-1.69 (m, 9H, PCH₂CH₂, CH_Ad/CH_2,Ad), 1.79 (s, 15H,

C₅Me₅), 2.09-2.15 (m, 2H, CH_Ad/CH_2,Ad), 2.27-2.30 (m, 1H, CH_Ad/CH_2,Ad),

2.36-2.47 (m, 3H, CH_Ad/CH_2,Ad), 2.80-2.87 (m, 1H, PCH₂CH₂), 5.04-5.06

(m, 1H, C₅H₄), 5.40-5.42 (m, 1H, C₅H₄), 5.45-5.47 (m, 1H, C₅H₄), 6.40-

6.42 (m, 1H, C₅H₄), 7.06-7.09 (m, 1H, p-CH_PhP), 7.11-7.14 (m, 1H,

p-CH_PhP), 7.19-7.22 (m, 4H, 4×o-CH_PhP), 7.71-7.74 (m, 4H, 4×m-CH_PhP)

ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 299 K): δ = 12.6 (C₅Me₅), 22.8 (d,

¹J_C,P= 11.6 Hz, PCH₂), 27.5 (CH_Ad), 28.0 (CH_Ad), 31.0 (OC_qCH₃), 32.6

(CH_Ad), 33.0 (CH_Ad), 33.4 (CH_2,Ad), 34.8 (CH_2,Ad), 35.8 (d, ²J_C,P= 20.7 Hz,

PCH₂CH₂), 37.2 (CH_2,Ad), 37.3 (CH_2,Ad), 39.4 (CH_2,Ad), 54.7 (C_q,exo), 104.5

1164, 1152, 990, 845, 835, 772, 759, 726, 711, 660 cm^-1. ¹H NMR

(500 MHz, C₆D₆, 305 K): δ = 1.53 (s, 3H, OC_qCH₃), 1.94 (s, 15H, C₅Me₅),

1.97-1.98 (m, 1H, PCH₂CH₂), 2.11 (s, 3H, CH_3,p-tolyl), 2.17 (s, 3H,

CH_3,p-tolyl), 2.24-2.29 (m, 1H, PCH₂), 2.66-2.71 (m, 1H, PCH₂), 2.93-3.00

(m, 1H, PCH₂CH₂), 4.94-4.95 (m, 1H, C₅H₄), 5.41-5.42 (m, 1H, C₅H₄),

5.68-5.69 (m, 1H, C₅H₄), 6.82-6.83 (m, 2H, C₅H₄, CH_Aryl), 6.90-6.97 (m,

3H, 3×CH_Aryl), 7.05-7.14 (m, 7H, 7×CH_Aryl), 7.38-7.41 (m, 1H, CH_Aryl),

7.47-7.59 (m, 5H, 4×m-CH_PhP, CH_Aryl), 7.70-7.71 (m, 1H, CH_Aryl) ppm.

¹³C{¹H} NMR (126 MHz, C₆D₆, 305 K): δ = 11.9 (C₅Me₅), 20.9 (CH_3,p-tolyl),

1

21.0 (CH_3,p-tolyl), 24.0 (d, J_C,P= 11.3 Hz, PCH₂), 29.8 (OC_qCH₃), 39.2 (d,

3

²J_C,P= 19.4 Hz, PCH₂CH₂), 65.9 (C_q,exo), 105.4 (d, J_C,P= 13.7 Hz,

OC_qCH₃), 109.3 (C₅H₄), 109.4 (C₅H₄), 110.4 (C₅H₄), 118.2 (C₅H₄), 119.8

2

(C₅Me₅), 128.4 (p-CH_PhP)*, 128.5 (p-CH_PhP)*, 128.6 (d, J_C,P= 6.9 Hz,

2×o-CH_PhP), 128.68 (2×o-CH_p-tolylCH₃), 128.7 (d, ²J_C,P= 7.0 Hz,

2×o-CH_PhP), 129.1 (2×o-CH_p-tolylCH₃), 130.3 (2×m-CH_p-tolylCH₃), 130.9

3

(2×m-CH_p-tolylCH₃), 133.2 (d, J_C,P= 18.2 Hz, 2×m-CH_PhP), 133.5 (d,

3

(C₅H₄), 111.6 (C₅H₄), 111.7 (d, J_C,P= 13.9 Hz, OC_qCH₃), 112.7 (C₅H₄),

³J_C,P= 18.4 Hz, 2×m-CH_PhP), 135.8 (C_q,p-tolylCH₃), 136.1 (C_q,p-tolylCH₃),

139.7 (d, ¹J_C,P= 14.3 Hz, C_q,PhP), 140.7 (d, ¹J_C,P= 15.8 Hz, C_q,PhP), 141.5

(p-C_q,p-tolylCH₃), 143.6 (p-C_q,p-tolylCH₃), 147.4 (C_q,ipso) ppm. * = overlap with

C₆D₆signal. ³¹P{¹H} NMR (202 MHz, C₆D₆, 305 K): δ = -13.9 ppm. EA:

Anal. Calcd for C₄₆H₅₀ClHfOP: C, 63.96; H, 5.83. Found: C, 64.20; H,

6.17.

2

120.1 (C₅H₄), 123.7 (C₅Me₅), 127.9 (p-CH_PhP)*, 128.5 (d, J_C,P= 5.7 Hz,

2

2×o-CH_PhP), 128.77 (d, J_C,P= 6.8 Hz, 2×o-CH_PhP), 128.8 (p-CH_PhP),

3

132.7 (d, J_C,P= 17.1 Hz, 2×m-CH_PhP), 133.9 (d, J_C,P= 19.4 Hz, 2×m-

1

CH_PhP), 140.2 (d, J_C,P= 16.9 Hz, C_q,PhP), 142.1 (d, J_C,P= 16.5 Hz,

_q,PhP), 156.7 (C_q,ipso) ppm. * = overlap with C₆D₆signal. ³¹P{¹H} NMR

(202 MHz, C₆D₆, 299 K): -12.0 ppm. EA: Anal. Calcd for

₄₁H₅₀ClOPTi: C, 73.16; H, 7.49. Found: C, 72.07; H, 7.66.

C

δ

=

C

Synthesis of Ti5: To a solution of complex Ti4 (0.500 g, 0.743 mmol) in

15 mL of tetrahydrofuran was added a methyllithium solution (0.5 mL,

0.743 mmol; 1.6 M in diethyl ether). The reaction mixture was stirred for

16 h at room temperature. The solvent was completely removed under

vacuum, and the residue was dissolved in 12 mL of toluene. The solution

was filtered, and the residue was washed with toluene (2×10 mL). All

volatiles were removed under vacuum to give complex Ti5 as a pale

yellow solid. Crystals suitable for single crystal X-ray diffraction were

obtained from a saturated toluene solution at -26 °C. Yield: 0.398 g

(0.610 mmol, 82%). Melting point: 202-204 °C (dec.). IR (ATR): � = 2903,

2857, 1480, 1462, 1432, 1373, 1173, 1146, 1098, 1060, 1025, 982, 955,

874, 849, 813, 746, 734, 695, 659, 635, 581 cm^-1. ¹H NMR (500 MHz,

C₆D₆, 298 K): δ = 0.26 (s, 3H, TiCH₃), 1.32 (s, 3H, OC_qCH₃), 1.52-1.66

(m, 7H, CH_Ad/CH_2,Ad), 1.71 (s, 15H, C₅Me₅), 1.78-2.11 (m, 6H, PCH₂,

PCH₂CH₂, CH_Ad/CH_2,Ad), 2.22-2.30 (m, 2H, CH_Ad/CH_2,Ad), 2.35-2.42 (m,

1H, CH_Ad/CH_2,Ad), 2.48-2.50 (m, 1H, PCH₂CH₂), 2.70-2.73 (m, 1H,

CH_Ad/CH_2,Ad) 4.85-4.87 (m, 1H, C₅H₄), 5.07-5.09 (m, 1H, C₅H₄), 5.29-5.30

(m, 1H, C₅H₄), 6.14-6.15 (m, 1H, C₅H₄), 7.05-7.19 (m, 6H, 4×o-CH_PhP,

2×p-CH_PhP)*, 7.55-7.58 (m, 2H, 2×m-CH_PhP), 7.63-7.66 (m, 2H,

2×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 298 K): δ = 12.0

Synthesis of Zr4: In a glove box compound L2 (0.476 g, 1.857 mmol) in

n-hexane (3×5 mL) was added to a solution of complex Zr1 (0.854 g,

1.857 mmol) in 10 mL of n-hexane. The suspension was stirred for 16 h

at room temperature resulting in a colorless suspension. The supernatant

was decanted, the residue was washed with n-hexane (3×5 mL) and

dried under vacuum to yield Zr4 as a colorless solid. Crystals suitable for

single crystal X-ray diffraction of complex Zr4 were obtained from a

saturated toluene solution at room temperature. Yield: 0.558 g

(0.779 mmol, 42%). Melting point: 190-192 °C. IR (ATR): � = 3078, 3021,

2961, 2900, 2856, 1481, 1470, 1433, 1375, 1211, 1199, 1174, 1151,

1097, 1060, 1027, 999, 980, 960, 887, 872, 846, 820, 742, 696, 676, 657,

632, 563 cm^-1. ¹H NMR (500 MHz, C₆D₆, 299 K): δ = 1.27-1.35 (m, 2H,

CH_Ad/CH_2,Ad), 1.41 (s, 3H, OC_qCH₃), 1.48-1.72 (m, 9H, PCH₂CH₂,

CH_Ad/CH_2,Ad), 1.85 (s, 15H, C₅Me₅), 2.15-2.22 (m, 3H, PCH₂,

CH_Ad/CH_2,Ad), 2.33-2.39 (m, 1H, PCH₂), 2.44-2.54 (m, 3H, CH_Ad/CH_2,Ad),

5.31-5.33 (m, 1H, C₅H₄), 5.51-5.53 (m, 1H, C₅H₄), 5.68-5.70 (m, 1H,

C₅H₄), 6.18-6.20 (m, 1H, C₅H₄), 7.06-7.08 (m, 1H, p-CH_PhP), 7.10-7.13

(m, 1H, p-CH_PhP), 7.19-7.22 (m, 4H, 4×o-CH_PhP), 7.68-7.72 (m, 4H,

4×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 299 K): δ = 11.8

1

(C₅Me₅), 22.6 (d, J_C,P= 10.8 Hz, PCH₂), 27.7 (CH_Ad), 28.2 (CH_Ad), 30.8

1

(C₅Me₅), 22.8 (d, J_C,P= 11.5 Hz, PCH₂), 27.5 (CH_Ad), 28.0 (CH_Ad), 31.1

(OC_qCH₃), 32.88 (CH_Ad), 32.9 (CH_Ad), 33.7 (CH_2,Ad), 35.0 (CH_2,Ad), 35.3

2

(OC_qCH₃), 32.8 (CH_Ad), 33.1 (CH_Ad), 33.4 (CH_2,Ad), 34.9 (CH_2,Ad), 36.7 (d,

(TiCH₃), 36.6 (d, J_C,P= 19.8 Hz, PCH₂CH₂), 37.3 (CH_2,Ad), 37.4 (CH_2,Ad),

3

²J_C,P= 20.2 Hz, PCH₂CH₂), 37.2 (CH_2,Ad), 37.7 (CH_2,Ad), 39.6 (CH_2,Ad),

39.6 (CH_2,Ad), 54.9 (C_q,exo), 103.4 (C₅H₄), 107.4 (d, J_C,P= 12.9 Hz,

3

55.1 (C_q,exo), 105.4 (C₅H₄), 106.9 (d, J_C,P= 13.3 Hz, OC_qCH₃), 110.1

OC_qCH₃), 107.9 (C₅H₄), 108.6 (C₅H₄), 116.3 (C₅H₄), 118.6 (C₅Me₅), 128.1

(2×C₅H₄), 115.1 (C₅H₄), 120.5 (C₅Me₅), 128.0 (p-CH_PhP)*, 128.6 (d,

(p-CH_PhP)*, 128.6 (d, ²J_C,P= 5.8 Hz, 2×o-CH_PhP), 128.8 (d, ²J_C,P= 6.7 Hz,

2

3

²J_C,P= 5.8 Hz, 2×o-CH_PhP), 128.8 (d, J_C,P= 7.8 Hz, 2×o-CH_PhP, 128.9

2×o-CH_PhP), 128.9 (p-CH_PhP), 132.6 (d, J_C,P= 17.4 Hz, 2×m-CH_PhP),

3

1

(p-CH_PhP), 132.7 (d, ³J_C,P= 17.3 Hz, 2×m-CH_PhP), 133.8 (d,

³J_C,P= 19.4 Hz, 2×m-CH_PhP), 139.9 (d, ¹J_C,P= 16.4 Hz, C_q,PhP), 141.8 (d,

¹J_C,P= 16.2 Hz, C_q,PhP), 154.9 (C_q,ipso) ppm. * = overlap with C₆D₆signal.

³¹P{¹H} NMR (202 MHz, C₆D₆, 299 K): δ = -12.3 ppm. EA: Anal. Calcd for

133.7 (d, J_C,P= 19.2 Hz, 2×m-CH_PhP), 139.9 (d, J_C,P= 16.3 Hz, C_q,PhP),

1

141.9 (d, J_C,P= 15.6 Hz, C_q,PhP), 151.4 (C_q,ipso) ppm. * = overlay with

C₆D₆signal. ³¹P{¹H} NMR (202 MHz, C₆D₆, 298 K): δ = -12.7 ppm. EA:

Anal. Calcd for C₄₂H₅₃OPTi: C, 77.29; H, 8.18. Found: C, 75.25; H, 8.34.

C₄₁H₅₀ClOPZr: C, 68.73; H, 7.03. Found: C, 69.32; H, 7.13.

Synthesis of Zr5: To a solution of complex Zr4 (0.500 g, 0.698 mmol) in

15 mL of tetrahydrofuran was added a methyllithium solution (0.4 mL,

0.698 mmol; 1.6 M in diethyl ether). The reaction mixture was stirred for

16 h at room temperature. The solvent was completely removed, and the

residue was dissolved in 12 mL of toluene. The solution was filtered, and

the residue was washed with toluene (2×10 mL). All volatiles were

removed under vacuum to give complex Zr5 as a colorless solid. Yield:

0.442 g (0.635 mmol, 91%). Melting point: 167-169 °C (dec.). IR (ATR): �

= 2961, 2903, 2858, 1480, 1467, 1452, 1434, 1366, 1261, 1170, 1148,

Synthesis of Hf4: In a glove box compound L2 (0.213 g, 0.831 mmol) in

n-hexane (3×5 mL) was added to a solution of complex Hf1 (0.505 g,

0.831 mmol) in 10 mL of n-hexane. The suspension was stirred for 16 h

at room temperature resulting in

a pale yellow suspension. The

supernatant was decanted, the residue was washed with n-hexane

(3×3 mL) and dried under vacuum to yield Hf4 as a pale yellow solid.

Yield: 0.591 g (0.684 mmol, 82%). Melting point: 175-177 °C. IR (ATR): �

= 2885, 2831, 1525, 1493, 1474, 1392, 1381, 1371, 1278, 1254, 1178,

10.1002/ejic.201801016

European Journal of Inorganic Chemistry

FULL PAPER

1095, 1058, 1029, 999, 980, 963, 885, 871, 845, 803, 739, 695, 658, 632,

602, 559 cm^-1. ¹H NMR (500 MHz, C₆D₆, 298 K): δ = -0.07 (s, 3H, ZrCH₃),

1.36 (s, 3H, OC_qCH₃), 1.60-1.74 (m, 6H, CH_Ad/CH_2,Ad, PCH₂CH₂), 1.81 (s,

15H, C₅Me₅), 1.89-2.30 (m, 10H, CH_Ad/CH_2,Ad, PCH₂CH₂), 2.54-2.56 (m,

1H, CH_Ad/CH_2,Ad), 2.66-2.69 (m, 1H, CH_Ad/CH_2,Ad), 5.08-5.10 (m, 1H,

C₅H₄), 5.43-5.45 (m, 1H, C₅H₄), 5.54-5.55 (m, 1H, C₅H₄), 6.06-6.08 (m,

1H, C₅H₄), 7.05-7.13 (m, 2H, 2×p-CH_PhP), 7.16-7.19 (m, 4H,

4×o-CH_PhP)*, 7.56-7.59 (m, 2H, 2×m-CH_PhP), 7.63-7.66 (m, 2H,

2×m-CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 298 K): δ = 11.4

(C₅Me₅), 22.8 (d, ¹J_C,P= 11.3 Hz, PCH₂), 23.0 (ZrCH₃), 27.7 (CH_Ad), 28.2

(CH_Ad), 31.0 (OC_qCH₃), 32.9 (CH_Ad), 33.1 (CH_Ad), 33.6 (CH_2,Ad), 35.0

(CH_2,Ad), 37.2 (CH_2,Ad), 37.6 (d, ²J_C,P= 20.0 Hz, PCH₂CH₂), 37.8 (CH_2,Ad),

(m, 1H, CH_Ad/CH_2,Ad), 2.55-2.58 (m, 1H, CH_Ad/CH_2,Ad), 2.68-2.82 (m, 2H,

PCH₂), 3.00-1.11 (m, 1H, PCH₂CH₂), 4.81-4.82 (m, 1H, C₅H₄), 5.51-5.52

(m, 1H, C₅H₄), 5.83-5.87 (m, 1H, C₅H₄), 6.44-6.46 (m, 1H, C₅H₄), 7.02-

7.03 (m, 2H, 2×CH_Ph), 7.21-7.26 (m, 2H, 2×CH_Ph), 7.37-7.41 (m, 2H,

2×CH_Ph), 7.47-7.50 (m, 1H, 2×CH_Ph), 7.60-7.64 (m, 2H, 2×CH_Ph), 7.66-

7.69 (m, 1H, CH_Ph) ppm. ¹³C{¹H} NMR (126 MHz, CD₂Cl₂, 299 K): δ =

12.8 (BCH₃)*, 13.1 (C₅Me₅), 27.0 (CH_Ad), 27.7 (CH_Ad), 28.7 (d,

¹J_C,P= 28.7 Hz, PCH₂), 33.8 (CH_Ad), 34.1 (CH_2,Ad), 34.3 (OC_qCH₃), 34.6

(CH_2,Ad), 36.4 (CH_Ad), 36.6 (CH_2,Ad), 37.4 (CH_2,Ad), 38.9 (CH_2,Ad), 39.1 (d,

²J_C,P= 48.1 Hz, PCH₂CH₂), 55.0 (C_q,exo), 108.7 (C₅H₄), 111.1 (C₅H₄),

113.6 (C₅H₄), 113.9 (OC_qCH₃), 118.7 (C₅H₄), 126.0 (C₅Me₅), 128.8

2

1

(C_q,ArB)*, 129.1 (d, J_C,P= 8.9 Hz, 4×o-CH_PhP), 130.9 (d, J_C,P= 34.7 Hz,

3

39.8 (CH_2,Ad), 55.3 (C_q,exo), 104.3 (d, J_C,P= 13.0 Hz, OC_qCH₃), 104.8

C_q,PhP), 131.5 (p-CH_PhP), 132.8 (p-CH_PhP), 132.9 (d, J_C,P= 14.6 Hz,

(C₅H₄), 106.7 (C₅H₄), 107.6 (C₅H₄), 113.2 (C₅H₄), 117.2 (C₅Me₅), 128.1

4×m-CH_PhP), 133.8 (d, ¹J_C,P= 26.1 Hz, C_q,PhP), 136.8 (dm,

(p-CH_PhP)*, 128.6 (d, ²J_C,P= 5.9 Hz, 2×o-CH_PhP), 128.8 (d, ²J_C,P= 6.6 Hz,

¹J_C,F= 256.0 Hz, C_q,ArF), 137.9 (dm, J_C,F= 242.5 Hz, C_q,ArF), 148.7 (dm,

1

3

2×o-CH_PhP), 128.9 (p-CH_PhP), 132.6 (d, J_C,P= 17.5 Hz, 2×m-CH_PhP),

¹J_C,F= 239.1 Hz, C_q,ArF), 155.6 (C_q,ipso) ppm. * = assignment by ¹H/¹³C-

HMQC/HMBC spectra. ¹¹B{¹H} NMR (160 MHz, CD₂Cl₂, 299 K): δ = -15.5

ppm. ¹⁹F{¹H} NMR (470 MHz, CD₂Cl₂, 299 K): δ = -167.9 (m, 6F m-F_ArB),

-165.3 (t, ³J_F,F= 20.4 Hz, 3F, p-F_ArB), -133.1 (m, 6F, o-F_ArB) ppm. ³¹P{¹H}

NMR (202 MHz, CD₂Cl₂, 299 K): δ = 28.6 ppm. EA: Anal. Calcd for

3

1

133.7 (d, J_C,P= 19.2 Hz, 2×m-CH_PhP), 139.8 (d, J_C,P= 16.1 Hz, C_q,PhP),

1

141.7 (d, J_C,P= 15.6 Hz, C_q,PhP), 150.3 (C_q,ipso) ppm. * = overlay with

C₆D₆signal. ³¹P{¹H} NMR (202 MHz, C₆D₆, 298 K): δ = -12.9 ppm. EA:

Anal. Calcd for C₄₂H₅₃OPZr: C, 72.47; H, 7.67. Found: C, 71.41; H, 7.92.

C

₆₀H₅₃BF₁₅OPTi: C, 61.87; H, 4.59. Found: C, 61.67; H, 4.76. HR/MS

calculated: m/z = 637.3079 [M⁺]; measured (ESI): m/z = 637.3073.

Synthesis of Hf5: To a solution of complex Hf4 (0.200 g, 0.232 mmol) in

15 mL of tetrahydrofuran was added a methyllithium solution (0.2 mL,

0.698 mmol; 1.6 M in diethyl ether). The reaction mixture was stirred for

16 h at room temperature. The solvent was completely removed, and the

residue was dissolved in 8 mL of toluene. The solution was filtered, and

the residue was washed with toluene (2×8 mL). All volatiles were

removed under vacuum to give complex Hf5 as a colorless solid. Yield:

0.140 g (0.166 mmol, 72%). Melting point: 201-203 °C (dec.). IR (ATR): �

= 2916, 2870, 1645, 1584, 1509, 1475, 1435, 1377, 1369, 1261, 1196,

1149, 1093, 1060, 1024, 923, 889, 869, 857, 811, 798, 751, 740, 697,

664, 637 cm^-1. ¹H NMR (500 MHz, C₆D₆, 305 K): δ = -0.08 (s, 3H, HfCH₃),

1.31 (s, 3H, OC_qCH₃), 1.86 (s, 15H, C₅Me₅), 1.86-1.90 (m, 1H, PCH₂CH₂),

2.13 (s, 3H, CH_3,p-tolyl), 2.18-2.22 (m, 1H, PCH₂), 2.19 (s, 3H, CH_3,p-tolyl),

2.63-2.68 (m, 1H, PCH₂), 2.87-2.94 (m, 1H, PCH₂CH₂), 4.97-4.98 (m, 1H,

C₅H₄), 5.14-5.15 (m, 1H, C₅H₄), 5.44-5.46 (m, 1H, C₅H₄), 6.68-6.69 (m,

1H, C₅H₄), 6.83-6.85 (m, 1H, CH_Aryl), 6.90-7.18 (m, 12H, 12×CH_Aryl),

7.49-7.56 (m, 4H, 4×m-CH_PhP), 7.84-7.86 (m, 1H, CH_Aryl) ppm. ¹³C{¹H}

NMR (126 MHz, C₆D₆, 305 K): δ = 11.5 (C₅Me₅), 20.9 (CH_3,p-tolyl), 21.0

(CH_3,p-tolyl), 24.1 (d, ¹J_C,P= 10.7 Hz, PCH₂), 27.8 (HfCH₃), 30.4 (OC_qCH₃),

Synthesis of Zr6: A mixture of complex Zr5 (0.250 g, 0.359 mmol) and

B(C₆F₅)₃(0.184 g, 0.359 mmol) was stirred in 10 mL of toluene. When

the stirring process is stopped after a few minutes, the development of

two phases can be observed due to the formation of complex Zr6. The

solvent was decanted, the residue was washed with n-hexane (3×5 mL)

and dried under vacuum to give complex Zr6 as a colorless solid. Yield:

0.393 g (0.325 mmol, 91%). Melting point: 85-87 °C. IR (ATR): � = 2912,

2860, 1641, 1509, 1454, 1379, 1267, 1081, 965, 951, 935, 842, 805, 743,

694, 659, 644, 632, 605, 567 cm^-1. ¹H NMR (500 MHz, CD₂Cl₂, 296 K): δ

= 0.49 (s(br), 3H, BCH₃), 1.52-1.59 (m, 2H, CH_Ad/CH_2,Ad), 1.67 (s, 3H,

OC_qCH₃), 1.71-1.81 (m, 3H, CH_Ad/CH_2,Ad), 1.90 (s, 15H, C₅Me₅), 1.96-

2.23 (m, 9H, PCH₂CH₂, CH_Ad/CH_2,Ad), 2.54-2.75 (m, 3H, PCH₂,

CH_Ad/CH_2,Ad), 2.79-2.88 (m, 1H, PCH₂CH₂), 5.29-5.30 (m, 1H, C₅H₄),

5.75-5.76 (m, 1H, C₅H₄), 5.80-5.81 (m, 1H, C₅H₄), 6.43-6.44 (m, 1H,

C₅H₄), 7.14-7.17 (m, 2H, 2×CH_PhP), 7.28-7.32 (m, 2H, 2×CH_PhP), 7.43-

7.46 (m, 2H, 2×CH_PhP), 7.50-7.53 (m, 1H, CH_PhP), 7.63-7.66 (m, 2H,

2×CH_PhP), 7.69-7.71 (m, 1H, CH_PhP) ppm. ¹³C{¹H} NMR (126 MHz,

CD₂Cl₂, 296 K): δ = 11.9 (BCH₃)*, 12.0 (C₅Me₅), 25.1 (PCH₂)*, 27.2

(CH_Ad), 27.9 (CH_Ad), 33.4 (CH_Ad), 33.9 (CH_2,Ad), 34.3 (CH_Ad), 34.6

(CH_2,Ad), 35.7 (PCH₂CH₂)*, 36.2 (OC_qCH₃), 37.1 (CH_2,Ad), 37.4 (CH_2,Ad),

39.3 (CH_2,Ad), 55.8 (C_q,exo), 109.1 (C₅H₄), 109.5 (OC_qCH₃), 111.9 (C₅H₄),

3

38.9 (PCH₂CH₂), 66.1 (C_q,exo), 103.4 (d, J_C,P= 13.2 Hz, OC_qCH₃), 106.0

(C₅H₄), 108.8 (C₅H₄), 109.0 (C₅H₄), 116.3 (C₅H₄), 116.7 (C₅Me₅), 128.3

(2×o-CH_p-tolylCH₃)*, 128.4 (p-CH_PhP)*, 128.5 (p-CH_PhP), 128.6 (d,

2

²J_C,P= 5.8 Hz, 2×o-CH_PhP), 128.7 (d, J_C,P= 5.8 Hz, 2×o-CH_PhP), 129.0

1

(2×o-CH_p-tolylCH₃), 130.5 (2×m-CH_p-tolylCH₃), 131.1 (2×m-CH_p-tolylCH₃),

112.5 (C₅H₄), 115.6 (C₅H₄), 123.9 (C₅Me₅), 129.2 (d, J_C,P= 36.3 Hz,

3

2

133.2 (d, J_C,P= 18.2 Hz, 2×m-CH_PhP), 133.5 (d, J_C,P= 18.6 Hz, 2×m-

CH_PhP), 135.6 (C_q,p-tolylCH₃), 135.9 (C_q,p-tolylCH₃), 140.0 (d, ¹J_C,P= 14.5 Hz,

C_q,PhP), 129.4 (C_q,ArB)*, 129.7 (d, J_C,P= 9.2 Hz, 2×o-CH_PhP), 130.7 (d,

1

²J_C,P= 10.1 Hz, 2×o-CH_PhP), 130.8 (d, J_C,P= 30.7 Hz, C_q,PhP), 131.7

1

3

C_q,PhP), 140.7 (d, J_C,P= 16.2 Hz, C_q,PhP), 143.2 (p-C_q,p-tolylCH₃), 143.3

(p-CH_PhP), 132.2 (d, J_C,P= 13.2 Hz, 2×m-CH_PhP), 133.3 (p-CH_PhP),

(p-C_q,p-tolylCH₃), 143.9 (C_q,ipso) ppm. * = overlay with C₆D₆signal. ³¹P{¹H}

NMR (202 MHz, C₆D₆, 305 K): δ = -14.0 ppm. EA: Anal. Calcd for

133.4 (d, J_C,P= 14.1 Hz, 2×m-CH_PhP), 136.8 (dm, J_C,F= 247.7 Hz,

C

3

1

_q,ArF), 138.0 (dm, J_C,F= 250.7 Hz, C_q,ArF), 148.7 (dm, J_C,F= 250.2 Hz,

C₄₇H₅₃HfOP: C, 66.93; H, 6.33. Found: C, 65.61; H, 6.61.

_q,ArF), 155.5 (C_q,ipso) ppm. * = assignment by ¹H/¹³C-HMQC/HMBC

spectra. ¹¹B{¹H} NMR (160 MHz, CD₂Cl₂, 296 K): δ = -14.9 ppm. ¹⁹F{¹H}

NMR (470 MHz, CD₂Cl₂, 296 K): δ = -167.8 (m, 6F, m-F_ArB), -165.3 (t,

³J_F,F= 20.4 Hz, 3F, p-F_ArB), -133.1 (m, 6F, o-F_ArB) ppm. ³¹P{¹H} NMR

Synthesis of Ti6: A mixture of complex Ti5 (0.400 g, 0.613 mmol) and

B(C₆F₅)₃(0.314 g, 0.613 mmol) was stirred in 10 mL of toluene. When

the stirring process is stopped after a few minutes, the development of

two phases can be observed due to the formation of complex Ti6. The

solvent was decanted, the residue was washed with n-hexane (3×5 mL)

and dried under vacuum to give complex Ti6 as an orange solid. Yield:

0.603 g (0.505 mmol, 82%). Melting point: 92-94 °C. IR (ATR): � = 2914,

2861, 1641, 1509, 1485, 1454, 1379, 1267, 1081, 977, 965, 947, 933,

830, 805, 784, 744, 697, 660, 649, 633, 604, 569 cm^-1. ¹H NMR

(500 MHz, CD₂Cl₂, 299 K): δ = 0.48 (s(br), 3H, BCH₃), 1.57-1.76 (m, 8H,

CH_Ad/CH_2,Ad), 1.70 (s, 3H, OC_qCH₃), 1.89 (s, 15H, C₅Me₅), 1.95-2.02 (m,

2H, CH_Ad/CH_2,Ad), 2.08-2.20 (m, 3H, PCH₂CH₂, CH_Ad/CH_2,Ad), 2.37-2.38

(202 MHz, CD₂Cl₂, 296 K):

δ = 14.4 ppm. EA: Anal. Calcd for

C

₆₀H₅₃BF₁₅OPZr: C, 59.65; H, 4.42. Found: C, 57.63; H, 4.86. HR/MS

calculated: m/z = 679.2646 [M⁺]; measured (ESI): m/z = 679.2620.

Synthesis of Hf6: A mixture of complex Hf5 (0.100 g, 0.119 mmol) and

B(C₆F₅)₃(0.061 g, 0.119 mmol) was stirred in 10 mL of toluene. When

the stirring process is stopped after a few minutes, the development of

two phases can be observed due to the formation of complex Hf6. The

solvent was decanted, the residue was washed with n-hexane (3×5 mL)

and dried under vacuum to give complex Hf6 as a colorless solid. Yield:

10.1002/ejic.201801016

European Journal of Inorganic Chemistry

FULL PAPER

0.127 g (0.094 mmol, 79%). Melting point: 89-91 °C. IR (ATR): � = 3031,

2917, 2861, 1641, 1589, 1509, 1455, 1380, 1266, 1082, 951, 935, 910,

814, 743, 688 cm^-1. ¹H NMR (500 MHz, CD₂Cl₂, 305 K): δ = 0.51 (s, 3H,

BCH₃)*, 1.67-1.69 (m, 1H, PCH₂CH₂), 1.86 (s, 3H, OC_qCH₃), 2.05 (s, 15H,

C₅Me₅), 2.11 (s, 3H, CH_3,p-tolyl), 2.29-2.31 (m, 2H, PCH₂CH₂), 2.35 (s, 3H,

CH_3,p-tolyl), 2.77-2.85 (m, 1H, PCH₂CH₂), 5.04-5.05 (m, 1H, C₅H₄), 5.33-

5.35 (m, 1H, C₅H₄), 5.90-5.91 (m, 1H, C₅H₄), 6.35-6.36 (m, 1H, C₅H₄),

6.95-7.12 (m, 4H, 4×CH_Aryl)**, 7.15-7.20 (m, 3H, 3×CH_Aryl), 7.35-7.44 (m,

overlap with C₆D₆signal. ³¹P{¹H} NMR (202 MHz, C₆D₆, 300 K): δ = -4.8,

-4.0 ppm. HR/MS calculated: m/z = 727.2927 [M+Li⁺]; measured (ESI):

m/z = 727.2917.

Synthesis of Ti8: To a solution of complex Ti7 (0.250 g, 0.347 mmol) in

10 mL of tetrahydrofuran was added a methyllithium solution (0.2 mL,

0.347 mmol; 1.6 M in diethyl ether). The reaction mixture was stirred for

16 h at room temperature. The solvent was completely removed under

vacuum, and the residue was dissolved in 8 mL of toluene. The solution

was filtered, and the residue was washed with toluene (2×6 mL). All

volatiles were removed under vacuum to give complex Ti8 as a yellow

solid. Crystals suitable for single crystal X-ray diffraction were obtained

from a saturated n-hexane solution at -4 °C. Yield: 0.226 g (0.323 mmol,

93%). Melting point: 206-208 °C (dec.). IR (ATR): � = 2954, 2937, 2900,

2850, 1473, 1450, 1434, 1375, 1260, 1133, 1098, 1072, 1057, 1037,

1020, 995, 933, 838, 812, 779, 764, 745, 697, 679, 652, 639, 517, 601

cm^-1. ¹H NMR (500 MHz, C₆D₆, 305 K): δ = 0.62 (s, 3H, TiCH₃), 1.09-1.18

(m, 2H, 2×CH_Ad/CH_2,Ad), 1.60 (s, 15H, C₅Me₅), 1.64-1.71 (m, 5H,

5×CH_Ad/CH_2,Ad), 1.89-1.95 (m, 2H, 2×CH_Ad/CH_2,Ad), 2.03-2.05 (m, 1H,

CH_Ad/CH_2,Ad), 2.24 (s, 3H, OC_qCH₃), 2.61-2.71 (m, 3H, 3×CH_Ad/CH_2,Ad),

3.64-3.68 (m, 1H, CH_Ad/CH_2,Ad), 4.77-4.79 (m, 1H, C₅H₄), 5.02-5.04 (m,

1H, C₅H₄), 5.47-5.48 (m, 1H, C₅H₄), 6.67-6.68 (m, 1H, C₅H₄), 6.86-6.89

(m, 1H, C₆H₄), 7.01-7.19 (m, 7H, 7×CH_Aryl)*, 7.25-7.27 (m, 1H, C₆H₄),

7.33-7.36 (m, 2H, 2×m-CH_PhP), 7.40-7.43 (m, 2H, 2×m-CH_PhP), 7.80-

7.82 (m, 1H, C₆H₄) ppm. ¹³C{¹H} NMR (126 MHz, C₆D₆, 305 K): δ = 12.1

4H, 4×CH_Aryl), 7.45-7.54 (m, 3H, 3×CH_Aryl), 7.62-7.69 (m, 4H, 4×CH_Aryl

)

ppm. ¹³C{¹H} NMR (126 MHz, CD₂Cl₂, 305 K)***: δ = 10.0 (BCH₃)*, 12.2

(C₅Me₅) 20.9 (CH_3,p-tolyl), 21.0 ( CH_3,p-tolyl), 22.6 (d, ¹J_C,P= 23.1 Hz, PCH₂),

32.2 (OC_qCH₃), 37.4 (PCH₂CH₂), 66.1 (C_q,exo), 106.4 (OC_qCH₃), 110.0

(C₅H₄), 113.5 (C₅H₄), 114.7 (C₅H₄), 115.9 (C₅H₄), 123.0 (C₅Me₅), 129.1

1

(C_q,ArB)*, 148.8 (dm, J_C,F= 246.2 Hz, C_q,ArF), 150.8 (C_q,ipso) ppm. * =

assignment by ¹H/¹³C-HMQC/HMBC spectra. ** = overlay with signals of

toluene (residue).*** = only clearly assignable signals listed (residue of

toluene and close position of signals in the range between 125 and 135

ppm). ¹¹B{¹H} NMR (160 MHz, CD₂Cl₂, 305 K): δ = -14.9 ppm. ¹⁹F{¹H}

NMR (470 MHz, CD₂Cl₂, 305 K): δ = -167.9 (m, 6F, m-F_ArB), -165.3 (t,

³J_F,F= 20.4 Hz, 3F, p-F_ArB), -133.2 (m, 6F, o-F_ArB) ppm. ³¹P{¹H} NMR

(202 MHz, CD₂Cl₂, 305 K):

δ = 16.6 ppm. EA: Anal. Calcd for

C₆₅H₅₃BF₁₅HfOP: C, 57.60; H, 3.94. Found: C, 60.28; H, 4.21.

Synthesis of Ti7: Complex Ti1 (0.250 g, 0.600 mmol) and the ligand

precusor L3 (0.183 g, 0.600 mmol) were suspended in 10 mL of

n-hexane, resulting in a yellow suspension. The reaction mixture was

stirred for 16 h at room temperature. The solid was separated, washed

with n-hexane (3×5 mL) and dried under vacuum to give Ti9 as a yellow

solid (mixture of both diastereoisomers 1:1). NMR data is given for both

diastereoisomers without exact assignment. Crystals suitable for single

crystal X-ray diffraction were obtained from a saturated toluene solution

at -4 °C. Yield: 0.345 g (0.478 mmol, 80%). Melting point: 160-162 °C

(dec.). IR (ATR): � = 2931, 2903, 2851, 1584, 1475, 1454, 1434, 1382,

1374, 1211, 1183, 1131, 1084, 1070, 1057, 1041, 1020, 996, 927, 914,

892, 880, 837, 826, 817, 782, 767, 747, 697, 680, 650, 640, 603 cm^-1. ¹H

NMR (500 MHz, C₆D₆, 300 K): δ = 1.05-1.08 (m, 2H, 2×CH_Ad/CH_2,Ad),

1.20-1.27 (m, 2H, 2×CH_Ad/CH_2,Ad), 1.41-1.43 (m, 1H, CH_Ad/CH_2,Ad), 1.50-

1.66 (m, 10H, 10×CH_Ad/CH_2,Ad), 1.70 (s, 15H, C₅Me₅), 1.78 (s, 15H,

C₅Me₅), 1.81-1.94 (m, 4H, 4×CH_Ad/CH_2,Ad), 2.01-2.04 (m, 1H,

CH_Ad/CH_2,Ad), 2.12-2.15 (m, 1H, CH_Ad/CH_2,Ad), 2.27 (s, 3H, OC_qCH₃),

2.43-2.44 (m, 2H, 2×CH_Ad/CH_2,Ad), 2.58-2.59 (m, 4H, OC_qCH₃,

CH_Ad/CH_2,Ad), 2.78-2.81 (m, 2H, 2×CH_Ad/CH_2,Ad), 3.38-3.41 (m, 1H,

CH_Ad/CH_2,Ad), 3.66-3.70 (m, 1H, CH_Ad/CH_2,Ad), 5.15-5.16 (m, 1H, C₅H₄),

5.18-5.19 (m, 1H, C₅H₄), 5.23-5.24 (m, 1H, C₅H₄), 5.27-5.28 (m, 1H,

C₅H₄), 5.59-5.60 (m, 1H, C₅H₄), 5.75-5.76 (m, 1H, C₅H₄), 6.77-7.78 (m,

1H, C₅H₄), 6.88-6.96 (m, 2H, 2×CH_Aryl), 7.03-7.14 (m, 14H, C₅H₄,

13×CH_Aryl), 7.24-7.27 (m, 1H, CH_Aryl), 7.31-7.42 (m, 10H, 10×CH_Aryl),

7.74-7.77 (m, 1H, CH_Aryl), 8.53-8.56 (m, 1H, CH_Aryl) ppm. ¹³C{¹H} NMR

(126 MHz, C₆D₆, 300 K): δ = 12.9 (C₅Me₅), 13.1 (C₅Me₅), 27.4 (CH_Ad),

27.5 (CH_Ad), 27.52 (CH_Ad), 27.7 (CH_Ad), 28.8 (d, ⁴J_C,P= 32.6 Hz, OC_qCH₃),

32.0 (d, ⁴J_C,P= 32.4 Hz, OC_qCH₃), 33.1 (CH_Ad), 33.7 (CH_Ad), 34.3 (CH_2,Ad),

34.4(CH_2,Ad), 34.7 (CH_2,Ad), 34.9 (CH_2,Ad), 35.1 (CH_Ad), 36.2 (CH_Ad), 37.0

(CH_2,Ad), 37.3 (CH_2,Ad), 37.5 (CH_2,Ad), 37.9 (CH_2,Ad), 38.9 (CH_2,Ad), 39.0

(CH_2,Ad), 57.0 (C_q,exo), 57.8 (C_q,exo), 104.2 (C₅H₄), 104.6 (C₅H₄), 104.9

(C₅H₄), 106.8 (C₅H₄), 114.8 (C₅H₄), 115.6 (C₅H₄), 115.9 (d, ³J_C,P= 3.3 Hz,

4

(C₅Me₅), 27.7 (CH_Ad), 27.9 (CH_Ad), 32.7 (d, J_C,P= 32.8 Hz, OC_qCH₃),

33.5 (CH_Ad), 34.8 (CH_2,Ad), 34.9 (CH_2,Ad), 35.0 (TiCH₃), 36.3 (CH_Ad), 37.5

(CH_2,Ad), 37.6 (CH_2,Ad), 39.3 (CH_2,Ad), 58.1 (C_q,exo), 103.1 (C₅H₄), 103.5

3

(C₅H₄), 110.2 (C₅H₄), 114.6 (d, J_C,P= 2.8 Hz, OC_qCH₃), 118.5 (C₅Me₅),

121.4 (C₅H₄), 127.3 (C₆H₄), 127.9 (C₆H₄)*, 128.3 (p-CH_PhP)*, 128.4

(p-CH_PhP)*, 128.7 (d, ²J_C,P= 6.4 Hz, 2×o-CH_PhP), 128.9 (d, ²J_C,P= 5.7 Hz,

2×o-CH_PhP), 131.1 (d,¹J_C,P= 24.7 Hz, C_q,CP), 132.7 (d, J_C,P=6.3 Hz,

H

6 4

3

C₆H₄), 133.9 (d, J_C,P= 19.6 Hz, 4×m-CH_PhP), 136.7 (C₆H₄), 139.1 (d,

¹J_C,P= 13.6 Hz, C_q,PhP), 140.7 (d, J_C,P= 17.2 Hz, C_q,PhP), 149.4 (C_q,ispo),

1

2

156.5 (d, J_C,P= 22.3 Hz, o-C_q,CP) ppm. * = overlay with C₆D₆signal.

H

6 4

³¹P{¹H} NMR (202 MHz, C₆D₆, 305 K): δ = -3.6 ppm. HR/MS calculated:

m/z = 707.3474 [M+Li⁺]; measured (ESI): m/z = 707.3453.

Synthesis of Ti9: A mixture of complex Ti8 (0.150 g, 0.214 mmol) and

B(C₆F₅)₃(0.110 g, 0.214 mmol) was stirred in 10 mL of toluene. When

the stirring process is stopped after a few minutes, the development of

two phases can be observed due to the formation of complex Ti9. The

solvent was decanted, the residue was washed with n-hexane (3×5 mL)

and dried under vacuum to give complex Ti9 as an orange solid. Yield:

0.230 g (0.190 mmol, 89%). Melting point: 110-112 °C (dec.). IR (ATR): �

= 2961, 2910, 2855, 1639, 1509, 1454, 1380, 1265, 1175, 1119, 1082,

978, 965, 951, 830, 803, 749, 725, 696, 660, 643m 604 cm^-1. ¹H NMR

(500 MHz, CD₂Cl₂, 305 K): δ = 0.49 (s, 3H, BCH₃), 1.39-1.76 (m, 9H,

9×CH_Ad/CH_2,Ad), 1.88 (s, 15H, C₅Me₅), 2.05-2.06 (m, 1H, CH_Ad/CH_2,Ad),

2.09 (s, 3H, OC_qCH₃), 2.21-2.22 (m, 1H, CH_Ad/CH_2,Ad), 2.51-2.56 (m, 2H,

2×CH_Ad/CH_2,Ad), 2.72-2.75 (m, 1H, CH_Ad/CH_2,Ad), 3.68-3.70 (m, 1H, C₅H₄),

5.75-5.76 (m, 1H, C₅H₄), 5.87-5.91 (m, 1H, C₅H₄), 6.15-6.17 (m, 1H,

C₅H₄), 7.13-7.47 (m, 7H, 7×CH_Aryl), 7.51-7.55 (m, 2H, 2×CH_Aryl), 7.57-

7.60 (m, 1H, C₆H₄), 7.66-7.68 (m, 3H, 3×CH_Aryl), 8.08-8.11 (m, 1H, C₆H₄)

ppm. ¹³C{¹H} NMR (126 MHz, CD₂Cl₂, 305 K): δ = 9.7 (BCH₃)*, 12.9

(C₅Me₅), 27.0 (CH_Ad), 28.0 (CH_Ad), 32.9 (CH_Ad), 33.6 (CH_2,Ad), 34.9

(CH_2,Ad), 35.4 (OC_qCH₃), 35.9 (CH_Ad), 37.1 (CH_2,Ad), 37.5 (CH_2,Ad), 39.0

3

OC_qCH₃), 120.0 (d, J_C,P= 2.8 Hz, OC_qCH₃), 123.9 (C₅Me₅), 124.3

(C₅Me₅), 125.2 (C₅H₄), 126.4 (C₅H₄), 130.7 (d, ¹J_C,P= 24.4 Hz, C_q,CP),

H

6 4

1

131.5 (d, J_C,P= 26.2 Hz, C_q,CP), 138.4 (d, J_C,P= 14.0 Hz, C_q,PhP),

H

6 4

(CH_2,Ad), 57.6 (C_q,exo), 111.7 (C₅H₄), 112.8 (C₅H₄), 114.5 (d,

138.9 (d, ¹J_C,P= 13.3 Hz, C_q,PhP), 140.5 (d, ¹J_C,P= 16.3 Hz, C_q,PhP), 140.9

TS

J

= 2.0 Hz, C₅H₄), 117.3 (C₅H₄), 117.5 (OC_qCH₃), 126.2 (C₅Me₅),

C,P

1

(d, J_C,P= 17.9 Hz, C_q,PhP), 154.0 (C_q,ipso), 154.7 (C_q,ipso), 155.7 (d,

²J_C,P= 11.3 Hz, o-C_q,CP), 155.9 (d, J_C,P= 11.1 Hz, o-C_q,CP) ppm.

126.7 (d, J_C,P= 39.9 Hz, C_q,PhP), 128.1 (p-CH_PhP), 128.2 (p-CH_PhP),

128.7 (d, J_C,P= 17.9 Hz, C_q,CP), 128.9 (C_q,ArB)*, 129.2 (d,

¹J_C,P= 49.9 Hz, C_q,PhP), 130.2 (d, J_C,P= 9.6 Hz, 4×o-CH_PhP), 130.4 (d,

2

1

H

6 4

H

6 4

H

6 4

2

Signals of CH_Aryl: 126.8, 127.5, 127.9*, 128.4, 128.61, 128.66, 128.70,

128.72, 128.75, 128.77, 128.87, 128.92, 128.93, 128.98, 133.71, 133.74,

133.82, 133.86, 133.88, 133.90, 133.92, 134.0, 136.6, 137.0 ppm. * =

J

_C,P= 8.6 Hz, C₆H₄), 131.3 (d, J_C,P= 9.2 Hz, C₆H₄), 131.8 (C₆H₄), 132.7

3

1

(d, J_C,P= 10.6 Hz, 4×m-CH_PhP), 137.0 (dm, J_C,F= 244.5 Hz, C_q,ArF),

10.1002/ejic.201801016

European Journal of Inorganic Chemistry

FULL PAPER

1

138.0 (dm, J_C,F= 236.8 Hz, C_q,ArF), 139.2 (C₆H₄), 148.8 (dm,

[8]

[9]

M. Fischer, T. Oswald, H. Ebert, M. Schmidtmann, R. Beckhaus,

Organometallics 2018, 37, 415-421.

¹J_C,F= 237.1 Hz, C_q,ArF), 152.6 (d, J_C,P= 11.0 Hz, o-C_q,CP), 157.0

2

H

6 4

(C_q,ipso) ppm. * = assignment by ¹H/¹³C-HMQC/HMBC spectra. ¹¹B{¹H}

NMR (160 MHz, CD₂Cl₂, 305 K): δ = -14.9 ppm. ¹⁹F{¹H} NMR (470 MHz,

CD₂Cl₂, 305 K): δ = -167.9 (m, 6F, m-F_ArB), -165.3 (t, ³J_F,F= 20.3 Hz, 3F,

p-F_ArB), -133.1 (m, 6F, o-F_ArB) ppm. ³¹P{¹H} NMR (202 MHz, CD₂Cl₂, 305

K): δ = 41.4 ppm. HR/MS calculated: m/z = 685.3079 [M⁺]; measured

(ESI): m/z = 685.3075.

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Acknowledgements

Financial Support by the DFG Research Training Group 2226 is

kindly acknowledged.

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10.1002/ejic.201801016

European Journal of Inorganic Chemistry

FULL PAPER

Entry for the Table of Contents

Layout 2:

FULL PAPER

Ph₂P

Cationic group

tridentate Cp,O,P-ligands*

4 complexes with

O

Ph₂

P

Cl

M

Me

F_{5 3}

)

B(C₆

O

Malte Fischer, Maximilian Jaugstetter,

Raoul Schaper, Marc Schmidtmann,

Rüdiger Beckhaus*

PPh₂

O

R

=

M

Ti, Zr, Hf

side reactions

Page No. – Page No.

Reactions of π-η⁵:σ-η¹-monopentafulvene complexes to cationic d⁰complexes of

each group 4 metal with tridentate Cp,O,P-ligands by a convenient three-step

synthetic pathway (insertion of bidentate O,P-ligand precursors, subsequent

methylation, activation with B(C₆F₅)₃) are reported. Starting with acetylphosphine as

the ligand precursor, side reactions are initiated, dependent on the group 4 metal.

Cationic group 4 complexes (M = Ti,

Zr, Hf): Modifications and Limitations

in the design of tridentate Cp,O,P-

ligand frameworks built directly in the

coordination sphere of the metal

Article Doi

Cationic Group 4 Complexes (M = Ti, Zr, Hf): Modifications and Limitations in the Design of Tridentate Cp,O,P-Ligand Frameworks Built Directly in the Coordination Sphere of the Metal

DOI: 10.1002/ejic.201801016

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Article abstract of DOI:10.1002/ejic.201801016

Full text of DOI:10.1002/ejic.201801016

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