Alternative reaction pathways in domino reactions of hydrazinediidozirconium complexes with alkynes

FULL PAPER

DOI: 10.1002/chem.201103497

Alternative Reaction Pathways in Domino Reactions of

Hydrazinediidozirconium Complexes with Alkynes

Thorsten Gehrmann, Solveig A. Scholl, Julio Lloret Fillol, Hubert Wadepohl, and

Lutz H. Gade*^[a]

Dedicated to Professor Walter Siebert on the occasion of his 75th birthday

Abstract: Reaction of [Zr

ACHTUNGTRENNUNG(NMe₂)₂] (Ar=3,5-xylyl: 2a, mesityl:

G

high yields. Similar reactivity was ob-

served by reacting bis-amido complex

2b with one molar equivalent of the

corresponding alkyne and diphenylhy-

drazine. The formation of the seven-

membered zirconacycles implied a key

coupling step that involved the alkyne

and one of the aryl rings of the diphe-

nylhydrazinediido ligand. In some

cases, such as the reaction with 2-

butyne, the corresponding metallacycle

was only obtained in modest yields

(45% for the reaction with 2-butyne)

and a second major product, vinylimido

complex 9, was formed in almost equal

amounts (42%) by 1,2-amination

(formal insertion of the alkyne). The

formation of compounds 7a and 9 fol-

lowed in part the same sequence of re-

action steps and a key intermediate, an

azirinido complex, represented a “bi-

furcation point” in the reaction net-

work. Reaction of 1.2 equivalents of

several diarylhydrazines and various

substituted alkynes (1 equiv) at ambi-

ent temperature (or at 808C) in the

2b) with one or two molar equivalents

of 1,1-diphenylhydrazine gave the

mixed amido/hydrazido(1ꢀ) complex

[Zr

the

N

U

ACHTUNGTRENNUNG{(NMes)₂N_py}ACHTUNGTRENNUNG

the presence of excess 4-dimethylami-

nopyridine (DMAP), hexacoordinate

hydrazinediidozirconium

[Zr{(NXyl)₂N_py}(=NN(Me)Ph)

(5) and [Zr{(NXyl)₂N_py}(=NNPh₂)-

(dmap)₂] (6). The reaction of one

equivalent of the zirconium–hydrazine-

diide [Zr{(NTBS)₂N_py}(NNPh₂)(py)] (1)

A

U

E

presence of 10 mol% [Zr

ACHTUNGTERN{NUNG (NXyl)₂N_py}-

R

ACHTUNGTRENNUNG

indole derivatives. On the other hand,

the replacement of 1,1-diarylhydrazines

by 1-methyl-1-phenyl hydrazine led to

head-to-head cis-1,3-enynes in good

yields.

A

ACHTUNGTRENNUNG

ꢀ

Keywords: alkynes · C N coupling ·

with disubstituted alkynes at RT for

16 h led to the formation of seven-

membered diazazirconacycles 7a–7e in

domino reactions · indoles · zirconi-

um

Introduction

ing hydrazones, which may either occur by direct coupling

with other unsaturated organic substrates^[3]or by a Fischer-

type conversion into indoles.^[5]Such complex cascades of re-

action steps are frequently referred to as “domino reac-

tions” and may provide the key to assembling complex mol-

ecules.^[6,7]There are relatively few examples of the use of

early-transition-metal catalysis, in particular by Group 4

metals, in such transformations. However, the development

of synthetic routes to N-heterocycles,^[8]as referred to above,

merits further research efforts.

ꢀ

Transformations of the M=N NR₂unit in Group 4 metal–

hydrazinediides^[1]typically constitute the addition of unsatu-

rated molecules to the highly polar M=N bond and the

ꢀ

facile fragmentation of the N N bond. Both processes may

occur sequentially or almost concomitantly and may lead to

the combined formation and scission of several chemical

bonds in one process, including stoichiometric transforma-

ꢀ

tions that involve formal insertions into the N N bond, as

reported by Mountford and co-workers,^[2]as well as the tita-

nium catalyzed syntheses of N-heterocycles, as developed by

the groups of Odom, Beller, and others.^[3–5]The latter syn-

theses generally involve the catalytic hydrohydrazination of

an alkyne and the subsequent transformations of the result-

[a] Dr. T. Gehrmann, S. A. Scholl, Dr. J. L. Fillol, Prof. Dr. H. Wadepohl,

Prof. Dr. L. H. Gade

Anorganisch-Chemisches Institut

Universitꢀt Heidelberg

Im Neuenheimer Feld 270, 69120 Heidelberg (Germany)

Fax.: (+49)6221-545609

ꢀ

The potential of the M=N NR₂unit to undergo combined

ꢀ

N N-bond cleavage and N C coupling was first demonstrat-

ed by Bergman and co-workers in 1991 for [Cp₂Zr

ACHTUNGTRENNUNG(N₂Ph₂)-

E-mail: lutz.gade@uni-hd.de

AHCTUNGTRENNUNG

Supporting information for this article is available on the WWW

under http://dx.doi.org/10.1002/chem.201103497.

there is a rapidly growing body of work on the reactivity of

ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

3925

Chem. Eur. J. 2012, 18, 3925 – 3941

titanium–hydrazides, recent investigations into the chemistry

of their heavier Group 4 analogues have primarily focused

on the hydrazinediidozirconium complex [Zr

ACHTUNGTERN{NUNG (NTBS)₂N_py}-

ACHTUNGTRENNUNG

chiometric and catalytic reactivity towards unsaturated sub-

strates as found for titanium complexes. However, its reac-

tivity towards alkynes appears to be characterized by the ab-

ꢀ

sence of a hydrohydrazination step in favor of N N-bond

cleavage before the formation of a hydrazone.^[11]

We have recently reported a reaction sequence that offers

a route to indoles via a Zr-catalyzed non-Fischer-type path-

way.^[11]Closer inspection of this sequence revealed the com-

petition of more than one reaction pathway and that subtle

structural aspects of the reagent and substrate appeared to

determine its outcome. Herein, we provide a detailed ac-

count of this class of domino reactions within the coordina-

tion sphere of zirconium.

Results and Discussion

Synthesis and structural characterization of hydrazido(1ꢀ)-

zirconium and hydrazinediido(2ꢀ)zirconium complexes: Hy-

drazinediido analogues of compound 1 were difficult to

access from their dichlorozirconium precursors upon re-

placement of the silylamido units on the tripodal ancillary

ligand by the chemically more-robust arylamides. These

latter groups were thought to be particularly suitable for the

Scheme 1. Synthesis of hydrazido(1ꢀ)zirconium complexes 3 and 4, and

hydrazinediido complexes 5 and 6, starting from the bis-dimethylamido

complexes 2a and 2b.

development of catalytic reactions. We used [ZrACTHUNTRGNE{UNG (NAr)₂N_py}-

A

131.4(2)8 is comparable to that in the monohydrazido com-

mesityl substituents (2b)^[12]at the amido N moieties of the

supporting ligand (Scheme 1). The reaction of complex 2b

with one or two molar equivalents of 1,1-diphenylhydrazine

gave the mixed amido/hydrazido(1ꢀ) complex [Zr-

plex [ZrACTHUNGTERNNU{G (NTBS)₂N_py}ACHTNUGTREN(NUGN HNNPh₂)Cl] (130.7(4)8) reported pre-

viously by our group.^[13]

Hydrazinediido complexes 5 and 6 adopted distorted octa-

hedral coordination geometries. In both complexes, the hy-

drazinediido ligand was in a position trans to the pyridyl

fragment of the tridentate ligand. In contrast to the hydrazi-

do ligand in compound 3, the hydrazinediido ligands adopt-

ed an essentially linear coordination geometry (Zr-N(4)-

N(5) about 1768). A similar arrangement has been reported

for a hexacoordinate titanium–hydrazinediido complex by

Mountford and co-workers.^[14]

As expected for the formally dianionic hydrazinediido

ligand, the Zr–N bond was appreciably shorter (about

1.88 ꢂ) than that in hydrazido complex 3 (2.13 ꢂ). The

N(4)–N(5) bond lengths (N(4)–N(5) 5: 1.370(2), 6:

1.377(4)), as well as the Zr-N(4)-N(5) angles in compounds

5 and 6 (5: 175.6(1), 6: 176.3(2)8), were in good agreement

with those reported for other zirconium–hydrazinediides by

Bergman and co-workers^[9]and ourselves.^[10]

N

both complexes, thermally induced conversion into their cor-

responding hydrazinediido compounds was incomplete, even

in the presence of additional donors, such as pyridine or

DMAP. However, the reaction of the less-sterically shielded

N-3,5-xylyl-substituted bis-amido complex 2a with one

molar equivalent of diphenyl- or phenylmethylhydrazine in

the presence of an excess of DMAP gave the hexacoordi-

nate hydrazinediidozirconium complexes [Zr

NN(Me)Ph)(dmap)₂] (5) and [Zr{(NXyl)₂N_py}

(dmap)₂] (6) in good yields (Scheme 1). Whereas analogues

ACHTUNGTRENNUNG

syntheses have been reported in titanium hydrazinediide

chemistry,^[1d,f]this approach is unprecedented for zirconium.

The detailed structures of complexes 3, 5, and 6 were es-

tablished by X-ray diffraction. The molecular structures of

complexes 3 and 6 are shown in Figure 1 (for complex 5, see

the Supporting Information). The coordination geometry of

complex 3 is best described as distorted trigonal bipyrami-

dal, with the amido groups of the facial-coordinating tripo-

dal ligand occupying two equatorial positions. The pyridyl

fragment of the ligand and the monoanionic hydrazide are

coordinated in axial sites. The Zr-N(4)-N(5) angle of

Synthesis and structural characterization of diazazirconahep-

tenyl complexes. One possible reaction pathway of com-

plexes 1 and 2 with alkynes: Reaction of one equivalent of

the zirconium–hydrazinediide [ZrACHTNUGTRNNEUG{(NTBS)₂N_py}ACHTUGNTERN(NUGN NNPh₂)(py)]

(1) with disubstituted alkynes at room temperature for 16 h

led to the formation of seven-membered diazazirconacycles

7a–7e in high yields (Scheme 2). Similar reactivity was ob-

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Chem. Eur. J. 2012, 18, 3925 – 3941

Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

Figure 1. Molecular structures of complexes 3 and 6. Selected bond lengths [ꢂ] and angles [8] for compound 3: Zr–N(1)/N(2) 2.051(3)/2.075(3), Zr–N(3)

2.377(3), Zr–N(4) 2.125(3), Zr–N(6) 2.058(3), N(4)–N(5) 1.416(3); N(3)-Zr-N(4) 160.98(9), N(4)-Zr-N(6) 88.37(11), Zr-N(4)-N(5) 131.4(2). Selected bond

lengths [ꢂ] and angles [8] for compound 6: Zr–N(1)/N(2) 2.204(3)/2.194(3), Zr–N(3) 2.444(3), Zr–N(4) 1.885(3), Zr–N(6) 2.410(3), N(4)–N(5) 1.377(4);

N(3)-Zr-N(4) 168.0(1), N(4)-Zr-N(6) 95.3(1), Zr-N(4)-N(5) 176.3(2). Selected hydrogen atoms are omitted for clarity.

1

The analytical data and the H, ¹³C, and ¹⁵N NMR spectra

of compounds 7a–7e and 8a and 8b were in agreement with

the molecular structures (Scheme 2). In addition to the sym-

ꢀ ꢁ ꢀ

metric alkynes (R C C R; R=Me, Et, Ph, p-BrC₆H₄), the

unsymmetrically substituted 1-phenyl-1-propyne was tested,

which gave rise to two regioisomers (combined yield: 85%)

1

in a ratio of 65:35 (HNC(Me)/HNC(Ph), by H NMR spec-

troscopy).

The molecular structures of compounds 7b, 7c, 8a, and

8b were established by X-ray diffraction (Figure 1; selected

bond lengths and angles are listed in Table 1 and Table 2).

Table 1. Selected bond lengths and angles of complexes 7b and 7c.

7b

7c

Bond lengths [ꢂ]

Zr–N(1)/N(2)

Zr–N(3)

2.0732(14)/2.0483(13)

2.3898(15)

2.062(4)/2.047(3)

2.382(3)

Zr–N(4)

2.0983(15)

2.116(3)

Zr–N(5)

2.1304(15)

2.119(3)

C(1)–N(4)

1.393(2)

1.395(4)

C(1)–C(2)

1.359(2)

1.367(4)

Bond angles [8]

N(3)-Zr-N(4)

N(4)-Zr-N(5)

N(4)-C(1)-C(2)

Zr-N(4)-C(1)

Zr-N(4)-C(1)-C(2)

171.30(4)

87.40(5)

123.7(1)

137.0(1)

ꢀ44.1(2)

170.7(1)

85.6(1)

123.5(3)

136.7(2)

45.7(5)

Scheme 2. Synthesis of diazazirconacycloheptenes 7a–7e and 8a and 8b.

served by reacting bis-amido complex 2b with one molar

equivalent of the corresponding alkyne and diphenylhydra-

zine respectively. In contrast to the N-mesityl-substituted

complex (2b), its 3,5-xylyl-substituted analogue (2a) did not

form isolable diazazirconaheptenyl complexes, possibly as a

result of the less-efficient steric protection of the metallacy-

cle by the ancillary diamido-donor ligand. This property

does not rule out its formation, though, as was evident from

the reactive behavior of complex 2a in the catalytic reac-

tions discussed below.

The four molecular structures were very similar and there-

fore will be discussed together. The coordination geometry

of these complexes was typically distorted trigonal bipyrami-

dal. The amido groups of the facially coordinated tripodal

auxiliary ligand occupied two equatorial positions, whereas

one axial position was ligated by the neutral pyridyl group.

In the chelating bis-amido fragment, which resulted from

the metal-induced coupling reaction, the bulky diarylamido

unit was bonded at the equatorial position, whereas the

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L. H. Gade et al.

Table 2. Selected bond lengths and angles of complexes 8a, 8b, and 8c. The data for

the second independent molecule for compounds 8a and 8c are given in square brack-

ets.

C(1)-C(2) and Zr-N(4)-C(35)-C(34) torsion angles,

respectively, which were negative (thereby corre-

sponding to an anticlockwise rotation around the

N(4)–C bonds) in compounds 7b, 8a, and 8b, but

positive in compound 7c.

The non-planar diazazirconacycloheptenyl units

were conformationally stable on the NMR time-

scale. In all cases, the ¹H NMR spectra displayed

two individual sets of signals, which corresponded

to the CH₂groups and the TBDMS (compounds

7a–7e) or mesityl N-substituents (in compounds

8a, 8b) of the tripodal diamidopyridyl ligand. The

corresponding resonance patterns were also detect-

ed in the ¹³C NMR spectra. No dynamic effects (as

evidenced by signal broadening) were observed in

the NMR spectra, even at elevated temperatures.

The formation of the seven-membered zirconacy-

8a

8b

8c

Bond lengths [ꢂ]

Zr–N(1)

Zr–N(2)

Zr–N(3)

Zr–N(4)

2.055(2) [2.054(2)]

2.052(2) [2.065(2)]

2.363(2) [2.357(2)]

2.112(2) [2.106(2)]

2.113(2) [2.114(2)]

1.388(3) [1.394(3)]

1.348(3) [1.350(3)]

2.061(2)

2.067(2)

2.373(2)

2.111(2)

1.397(2)

1.356(3)

2.054(3) [2.048(3)]

2.060(2) [2.054(3)]

2.355(3) [2.355(3)]

2.106(4) [2.109(3)]

2.117(3) [2.113(3)]

1.393(5) [1.392(5)]

1.346(5) [1.344(6)]

Zr–N(5)

C(35)–N(4)

C(35)–C(34)

Bond angles [8]

N(3)-Zr-N(4)

N(4)-Zr-N(5)

N(4)-C(35)-C(34)

Zr-N(4)-C(35)

Zr-N(4)-C(35)-C(34)

167.51 (7) [160.73(7)]

84.22(7) [84.72(7)]

123.0(2) [122.3(2)]

135.1(2) [135.3(2)]

ꢀ34.7(3) [ꢀ43.9(3)]

161.81(6)

84.77(7)

123.5(2)

135.8(1)

ꢀ39.6(3)

160.8(1) [166.5(1)]

84.1(1) [84.4(1)]

122.8(4) [122.7(4)]

136.1(3) [135.3(3)]

40.2(6) [ꢀ35.8(6)]

comparatively smaller primary amide occupied the more-

crowded axial position. The Zr–N(4) and Zr–N(5) bond

lengths in the chelating bis-amide were within the typical

range for monoanionic nitrogen ligands bonded to a zirco-

nium(IV) center,^[15]and were in good agreement with those

reported previously by Berg-

cles (7a–7e and 8a and 8b) implied the operation of a key

coupling step that involved the alkyne and one of the aryl

rings of the diphenylhydrazinediido ligand. To gain an in-

sight into the nature of this intramolecular reaction, we in-

vestigated the reactivity of diphenylhydrazine derivatives in

man

and

co-workers^[9]

(2.131(3), 2.120(4) ꢂ). The

lengths of the carbon–carbon

bonds adjacent to N(4) in the

seven-membered diazazircona-

cycles (C(1)–C(2) in com-

pounds 7b and 7c, and C(35)–

C(34) in compounds 8a and 8b,

respectively) were consistent

with

C=C

double

bonds

(Figure 2). Furthermore, the

C(1)–N(4) distances for the si-

lylated ligand (7b: 1.3925(19);

7c: 1.395(4)) and the C(35)–

N(4) distances for the arylated

ligand (8a: 1.388(3) [1.394(3)];

8b: 1.397(2)) were slightly

shortened compared to a single

bond, which may be attributed

to the partial planarization at

the N(4) atom (a_Zr-N(4)-C(1): 7b:

137.02(10),

a_{Zr-N(4)-C(35)}

7c:

136.7(2);

:

8a: 135.13(15)

[135.26(16)], 8b: 135.80(14))

caused by N–Zr p-donation,

and delocalization of the lone

pair into the carbon p-system.

The main difference between

the four molecular structures

was the way in which the non-

planar diazazirconacycles were

twisted with respect to the an-

cillary tripod. This difference

Figure 2. Molecular structures of complexes 7b, 7c, 8a, and 8b (only one of the two independent molecules of

8a is shown). H atoms are omitted for clarity (except the NH atom). Selected bond lengths and angles are

was reflected in the Zr-N(4)- listed in Table 1 and Table 2.

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Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

in a 5:2 ratio. This general pattern was also confirmed by

the catalytic reactions of unsymmetrical diarylhydrazines

with alkynes, thereby leading to substituted indoles, which

will be discussed in detail below.

Synthesis and structural characterization of a vinylimidozir-

conium complex: An alternative reaction pathway of com-

plex 1 with an alkyne: Of the reactions of hydrazinediido

complex 1 (Scheme 2), the reaction with 2-butyne only gave

the corresponding metallacycle (7a) in modest yields. In situ

¹H NMR studies of the reaction revealed that compound 7a

only accounted for 45% of the converted starting material.

A second major product (9) was formed in almost equal

amounts (42%) along with some unidentified minor compo-

nents (Scheme 4).

Scheme 3. Synthesis of seven-membered metallacycles 8c and 8d by reac-

tion of complex 2b with butyne and mono-para-substituted diphenylhy-

drazines.

which one of the phenyl rings contained an electron-releas-

ing or -withdrawing substituent. In this context, complex 2b

was reacted with 2-butyne- and 1,1-diphenylhydrazine deriv-

atives, which were para-fluoro- or para-methyl-substituted

on one of the aryl rings (Scheme 3).^[16]For the former, only

one of the possible metallacyclic products was observed,

complex 8c, which resulted from the coupling of the more-

electron-rich unsubstituted aryl ring. Its molecular structure

was again established by X-ray diffraction (Figure 3). The

measured unit cell contained two stereoisomers that were

distinguishable by their torsion angle Zr-N(4)-C(35)-C(34)

(+40.2(6)8 [ꢀ35.8(6)8]).

Scheme 4. The two products (7a and 9) formed in almost-equal quantities

from the reaction of the hydrazinediidozirconium complex 1 with 2-

butyne.

This second major reaction product was the least soluble

in hydrocarbon solvents and could be separated as a pure

residue after extraction of the product mixture with pentane.

The analytical and NMR spectroscopic data of complex 9

were consistent with a vinylimido complex, which would be

formed by 1,2-amination (formal insertion of the alkyne),

with one coordinated molecule of pyridine. Such a species is

analogous to the reaction products reported by Mountford

and co-workers in their study of the reactivity of several ti-

tanium–hydrazides.^[2a,d]To confirm this hypothesis and to es-

tablish the structure of compound 9, single-crystal X-ray

analysis was carried out (Figure 4).

The coordination geometry of compound 9 was related to

the other molecular structures reported herein. The vinyli-

mido ligand was held in an equatorial position in the distort-

ed trigonal bipyramid, whilst the other coordination sites

were occupied by the tripodal spectator ligand and one ax-

ially bonded molecule of pyridine. The Zr–N(4) distance

(1.911(1) ꢂ) was in the typical range for a zirconium–nitro-

gen double bond.^[17]The C(1)–C(2) bond length of the vinyl

Figure 3. Molecular structure of complex 8c (only one of the two inde-

pendent molecules is shown). H atoms are omitted for clarity (except the

NH atom). Selected bond lengths and angles are listed in Table 2.

A similar reactive pattern was observed in the formation

of complex 8d, in which the major isomer was also formed

by attack of the more-electron-rich p-methylphenyl ring. In

this case, complex 8d and its regioisomer (8dꢀ) were formed

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3929

L. H. Gade et al.

tive of complex 1, in which one of the two N_b-bonded

phenyl rings was perdeuterated with half an equivalent of 3-

hexyne gave an NH/ND distribution in the reaction product

of 1:1, thereby indicating that k_H/k_D=1 and thus the absence

of a kinetic isotope effect. This result implied that neither

ꢀ

the C H-bond cleavage nor the H-atom rearrangement with

ꢀ

the formation of the N H bond, were involved in the rate-

determining step.

Based on the experimental evidence, computational mod-

eling of the mechanism of the reaction of zirconium com-

plex 1 with 2-butyne by DFT (B3PW91) revealed a potential

reaction pathway. This modeling has now been extended to

a comparative study for two alkynes, 2-butyne and dipheny-

lacetylene, to assess the influence that the nature of the

acetylene substrate has upon the reaction profile. More im-

portantly, we were interested to find out whether the forma-

tion of compounds 7a and 9 in part followed a similar path-

way and whether there was a common key reaction inter-

mediate that represented the point of bifurcation in the re-

action sequence.

First, the [2+2]-cycloaddition of 2-butyne and diphenyla-

cetylene to the Zr=N bond was modeled (Scheme 5: conver-

sion of I!IV). This reaction step had previously been stud-

ied in detail for titanium–hydrazides by Clot, Mountford,

and co-workers.^[2d]As for titanium, we found that cycloaddi-

tion occurred without prohibitive energetic barriers, thereby

giving rise to the metallacyclic intermediates IV_MeMeand

Figure 4. Molecular structure of imido complex 9. H atoms are omitted

for clarity. Selected bond lengths [ꢂ] and angles [8]: Zr–N(1) 2.088(1),

Zr–N(3) 2.324(1), Zr–N(4) 1.911(1), Zr–N(6) 2.397(1), C(1)–N(4)

1.363(2), C(1)–C(2) 1.360(2); N(3)-Zr-N(4) 98.69(6), N(4)-C(1)-C(2)

126.2(1), Zr-N(4)-C(1) 164.4(1).

substituent (1.360(2) ꢂ) was only insignificantly longer than

in the analogous titanium complex reported by Mountford

and co-workers (1.352 ꢂ).^[2a,d]

As we argue below, the formation of compounds 7a and 9

follows, in part, the same reaction sequence, and a key inter-

mediate represents a “bifurcation point” in the reaction net-

work. Both reaction pathways have similar selectivity deter-

mining activation barriers and the preference of one path-

way over the other in a given system is determined by

subtle structural aspects. This subtle preference was illustrat-

ed by the fact that the reaction of bis-amide 2a, which con-

tained an N-arylated ancillary tripod ligand, with one molar

equivalent of diphenyl hydrazine and 2-butyne quantitative-

ly afforded diazazirconaheptenyl complex 8a. No vinylimido

complex was formed in this reaction.

IV_PhPh

.

ꢀ

In a subsequent rate-determining step, the N N bond was

broken and “azaallyl” species V was formed; the activation

barrier (DG^°=21 kcalmol^ꢀ1) for 2-butyne was close to the

experimental value (24(ꢂ2) kcalmol^ꢀ1) that was observed

for the sterically more-demanding 3-hexyne. From metalla-

cyclic intermediates V_MeMeand V_PhPhno low-activation-bar-

rier pathways to the reaction products were found from a

systematic search of the active conformational and configu-

rational space. However, their rearrangement into their con-

stitutional isomers, azirinido complexes VI_MeMeand VI_PhPh

(Scheme 6), allowed the subsequent transformations to pro-

ceed without prohibitive activation barriers.^[17]

Modeling the reaction profile leading to type-7 metallacy-

cles or type-9 vinylimido complexes: The formation of com-

pounds 7a and 9 from the same reaction raised the question

to what extent these two reaction pathways coincided. A

previous mechanistic study had shed some light on the

mechanism that led to complexes 7a–7e.^[11]That mechanism

involved, inter alia, the reaction of the perdeuterated diphe-

nylhydrazinediide, which was also ¹⁵N-labeled at the N_a-po-

The conversion of intermediates VI_MeMeand VI_PhPhwas

found to be the key branching point in determining the

course of the reaction. In this context, the high ring-strain

and strongly electrophilic nature of the metalated azirine

unit was decisive. Attack upon the neighboring diphenylami-

do ligand may occur at two points, the ortho position of the

N-arene ring and the amido nitrogen atom, of which the

latter displayed marked nucleophilicity. Intermediates

VI_MeMeand VI_PhPhwere converted into their corresponding

seven-membered metallacyclic complexes, VIII_MeMeand

VIII_PhPh(Scheme 7), through nucleophilic attack of a carbon

atom in the ortho position of a phenyl ring of the NPh₂frag-

ment at one of the (electrophilic) carbon atoms of the meta-

lated azirine ring to form intermediates VII_MeMeand VII_PhPh

(DG=ꢀ20.7 and ꢀ13.5 kcalmol^ꢀ1, respectively) via the rela-

ꢀ ꢁ ꢀ

sition, with Et C C Et to cleanly afford the corresponding

metallacycle in which the enamido N atom was fully ¹⁵N-la-

beled and completely deuterated, thus clarifying the origin

of the NH group. Crossover experiments and the absence of

exchange with solvent hydrogen- or deuterium atoms con-

firmed the intramolecular nature of this rearrangement. A

ꢀ ꢁ ꢀ

kinetic study of the reaction of complex 1 with Et C C Et

revealed a pyridine-dissociation pre-equilibrium (the obser-

vation of saturation phenomena for high concentrations of

alkyne) and a subsequent rate-determining step that was

characterized by activation parameters of DH^°=11.5-

A

U

thus a free enthalpy of activation for the rate-determining

tively low activation barrier, TSACTHNGUTERNNUG

(VI-VII) (DG^°=19.8 and

step of DG₂₇₅^°=24(ꢂ2) kcalmol^ꢀ1. The reaction of a deriva-

18.3 kcalmol^ꢀ1, respectively).

3930

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Chem. Eur. J. 2012, 18, 3925 – 3941

Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

as discussed above. Notably,

transition states TS

ACHTUNGTRENUN(NG VI-IX) and

TS(VI-VII) should be viewed

AHCTUNGTRENNUNG

as very early owing to the high

electrophilicity of the attacking

carbon of the azirine ring.

En route to a catalytic forma-

tion of substituted indoles: As

mentioned above, Bergman and

co-workers showed that their

diazazirconacycles could be hy-

drolyzed with 5% HCl to yield

N-phenylindoles.^[9]Because hy-

drazides and amides have simi-

lar pK_avalues,^[20]and hydrazine

has been shown to replace

amido ligands (a method also

employed in this work), we

tried to protonate the zircona-

cycles by reacting them in tolu-

ene with a slight excess of di-

phenyl hydrazine.

The reaction of compounds

7a and 7b and 8a and 8b with

two molar equivalents of diphe-

nylhydrazine gave their corre-

Scheme 5. Reaction profile (DFT, B3PW91) of the cycloaddition of diphenylacetylene and 2-butyne to the hy-

ꢀ

drazinediido unit in compound 1 (I!IV_MeMe/IV_PhPh) and subsequent (rate-determining) N N-bond scission to

give the diphenylamido (azaallyl) intermediates V_MeMeand V_PhPh(R=TBS). Energies are given in parentheses,

free energies in square brackets.

sponding

bis-hydrazido(1ꢀ)

complexes 4a and 4, along with

one equivalent of 1-phenyl-2,3-

dimethylindole and 1-phenyl-

2,3-diethylindole

(Scheme 8).

On following the conversion of

compound 8a by ¹H NMR spec-

troscopy, only the disappear-

ance of the signals that were at-

tributed to the starting materi-

als and the growth of those as-

signed to complex 4 and 1-

phenyl-2,3-dimethylindole were

observed, along with some non-

specific degradation. No inter-

mediate species were detected

and the kinetics at low conver-

sion was first order in both

Scheme 6. Reaction profile (DFT, B3PW91) of the transformation of the [2+2] cycloaddition products IV_MeMe

and IV_PhPhinto the isomeric azaallyl intermediates V_MeMe/V_PhPhand Va_MeMe/Va_PhPhand into the key azirinido

species VI_MeMe/VI_PhPh(R=TBS). Energies are given in parentheses, free energies in square brackets.

Alternatively, the vinylimido products (IX; Me: DG=

ꢀ33.0 kcalmol^ꢀ1, Ph: DG=ꢀ27.2 kcalmol^ꢀ1) were directly

obtained from VI_MeMeand VI_PhPhthrough the transition

state TSACHTUNGTRENNUNG(VI-IX) via nucleophilic attack of the amido nitro-

gen on the electrophilic carbon on the metal-bonded azirine.

This transition state appeared to be slightly higher in free

compound 8a and the hydrazine. This result implied that

the rate-determining step was the initial attack of the hydra-

zine onto the metallacycle and that the subsequent transfor-

mations that led to compound 4 and the indole were rapid.

This situation was related to the non-observation of the pri-

mary products of the aminolysis of the metallacyclic inter-

mediate of the catalytic mechanism postulated for the

Group-4-metal-catalyzed hydroamination of alkynes.^[21,22]

Because bis-hydrazido complexes such as compounds 4a

and 4 may be precursors in the formation of hydrazinediido

compounds,^[13]the reaction sequence leading to the indoles

was thought to be part of a catalytic cycle for the direct gen-

enthalpy than TSACHTUNGTRENNUNG(VI-VII); however, given the accuracy of

the computational method,^[19]these differences may not be

significant. Thus, both pathways appeared to be feasible and

the selection of one over the other was expected to be gov-

erned by subtle structural variations in the substrates, which

was consistent with the experimentally observed behavior,

Chem. Eur. J. 2012, 18, 3925 – 3941

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3931

L. H. Gade et al.

The reaction of 1.2 equiva-

lents of several diarylhydrazines

and various substituted alkynes

(1 equiv) at ambient tempera-

ture (or at 808C) in the pres-

ence

of

10 mol%

[Zr-

A

ACHTUNGTRENN(NUG NMe₂)₂] (2a) gave

their corresponding indole de-

rivatives. For unsymmetrical in-

ternal alkynes, the indole with

the bulkier substituent at the 3-

position was the major product

(Table 3, Ind2 and Ind5),

whereas terminal alkynes exclu-

sively gave the indole substitut-

ed at the 3-position (Table 3,

Ind4, Ind6, Ind8, and Ind9). We

also noted that in the reactions

with unsymmetrical diarylhy-

drazines, the more-electron-rich

aryl ring was preferentially in-

corporated into the indole unit

(Table 4, Ind10 and Ind12).

This result was consistent with

the stoichiometric reactivity

shown in Scheme 3 and with

attack of the postulated azirini-

do fragment on the N-aryl ring

in intermediate VI (Scheme 7)

as the reaction of an electro-

phile with the “nucleophilic” ar-

omatic ring.

Scheme 7. Competitive reaction profiles (DFT, B3PW91) of the transformation the 2,3-azirinido species

VI_MeMeand VI_PhPhinto metallacycles VIII_MeMeand VIII_PhPhas well as into the vinylimido species IX_MeMeand

IX_PhPh(R=TBS). Energies are given in parentheses, free energies in square brackets.

The molecular structure of

Ind12, which showed the ex-

pected substitution pattern that

resulted

from

electrophilic

attack at the more-electron-rich

para-methoxy-substituted

phenyl ring, was established by

X-ray diffraction (Figure 5).

Based on the combined ex-

perimental and computational

evidence presented above, we

propose the mechanistic cycle

shown in Scheme 9 for the cata-

Scheme 8. Hydrazinolysis of the metallacyclic compounds 7a and 7b and 8a and 8b with diphenylhydrazine to

give bis-hydrazido complexes 4a/4 and the corresponding indoles.

eration of substituted indoles from alkynes and hydrazines

via metallacyclic intermediates, such as compounds 7a and

7b and 8a and 8b; that is, without involving hydrazones and

subsequent Fischer-type transformations.^[5]The reaction of

alkynes and 1,1-disubstituted hydrazines in the presence of

compounds 2a or 2b, even at elevated temperatures, did not

lead to the formation of hydrazones, even in trace quanti-

ties. Therefore, the zirconium–bis(dimethylamides) were not

catalyst precursors for the potential hydrohydrazination of

alkynes, but rather gave the isolated indoles through a dif-

ferent mechanistic pathway, as discussed above.

lytic formation of the N-substituted indoles from 1,2-diary-

lhydrazines and alkynes. The key intermediate, hydrazinedii-

do complex A, is formed by dissociation of the axial pyri-

dine ligand in a pre-equilibrium, as we observed experimen-

tally.

To our surprise, the replacement of 1,1-diarylhydrazines

by 1-methyl-1-phenylhydrazine changed the reactivity to-

wards alkynes dramatically: whilst reactions with disubstitut-

ed alkynes gave N-methyl indoles in poor yields, the at-

tempted conversion with terminal alkynes did not yield any

indole product at all. Instead, head-to-head cis-1,3-enynes

were formed selectively and in good yields, provided that

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Chem. Eur. J. 2012, 18, 3925 – 3941

Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

the terminal alkyne carried an aromatic substituent [Eq. (1)]

(see the Supporting Information).

At this stage, we are not able to suggest a mechanism for

coupling reactions at zirconium, but it is presumably very

similar to the reaction pathways proposed by Takaki and co-

workers^[23]for yttrium- and lanthanide catalysts.^[24]In that

work, amines were employed as co-catalysts, and, in our

case, the hydrazine also seems to play the role of a catalytic

proton-transfer reagent, albeit with greater activity and se-

lectivity.

Table 3. Catalytic indole syntheses of diphenylhydrazine with various alkynes.

Conclusion

The outcome of stoichiometric and catalytic

transformations that involve a cascade of reac-

tion steps crucially depends on the activation

barriers associated with each of their elementa-

ry transformations. It is assumed that several al-

ternative reaction pathways are often kinetically

Entry

Ind1

Alkyne

Indole

Ratio of

t

T

Yield

regioisomers^[a][h] [8C] [%]

accessible from

a given intermediate. Such

points of bifurcation in the resulting reaction

network are governed by small increments in

the free enthalpies of activation and thus subtle

structural variations of the substrate. In favora-

ble cases, such as the catalytic multistep synthe-

sis of indoles presented herein, a deeper under-

standing of the mechanism may offer insight

into the factors that determine the selectivity of

a given transformation.

–

24 RT 84

Ind2

Ind3

2:1

24 RT 59

Experimental Section

–

24 RT 36

All manipulations of air- and moisture-sensitive materials

were performed under an inert atmosphere of dry argon

by using standard Schlenk techniques or by working in a

glove box. Solvents were dried over sodium (toluene,

methyl cyclohexane), potassium (hexanes) or sodium/po-

tassium alloy (pentane, Et₂O), distilled, and degassed

prior to use. Deuterated solvents were dried over potassi-

um (C₆D₆, [D₈]toluene, [D₈]THF), vacuum distilled, and

stored in ampoules with Teflon valves under an argon at-

mosphere. Samples for NMR spectroscopy were prepared

under an argon atmosphere in 5 mm Wilmad tubes

Ind4

Ind5

>9:1^[b]

24 RT 74

1

equipped with J. Young Teflon valves. H, ¹³C, ²⁹Si, ¹⁹F and

¹⁵N NMR spectra were recorded on Bruker Avance 200,

400, and 600 NMR spectrometers and were referenced in-

ternally, by using the residual protiosolvent (¹H) or sol-

vent (¹³C) resonances, or externally, to CFCl₃or ¹⁵NH₃. El-

emental analysis was recorded by the analytical service at

the Heidelberg Chemistry Department. The hydrazinedii-

2:1^[b]

24 RT 56

do complex [Zr

N

ACHTUNGTRENNUNG

bis-amido complex [Zr

N

}ACHTUNGTRENNUNG

prepared according to literature procedures.^[10,12]Substitut-

ed diphenyl hydrazines, [D₁₀]¹⁵N_a-1,1-diphenylhydrazine

and [D₅]1,1-diphenylhydrazine were prepared according

to literature procedures for the parent compound.^[16]All

other reagents were obtained from commercial sources

and used as received unless otherwise stated.

Ind6

>9:1^[b]

24 RT 56

Preparation of [Zr

ACHTNUGNERT{NUGN (NMes)₂N_py}ACHTUNTREGG(NNUN NHNPh₂)CATHUNGTREN(UNGN NMe₂)] (3):

[Zr{(NMes)₂N_py(NMe₂)₂] (0.50 g, 0.86 mmol) and 1,1-di-

A

}ACHTUNGTRENNUNG

phenylhyadrazine (0.16 g, 0.86 mmol) were dissolved in

toluene (30 mL). After stirring the reaction mixture at RT

Chem. Eur. J. 2012, 18, 3925 – 3941

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3933

L. H. Gade et al.

2.29 (s, 6H; C₆H₂Me₃), 2.57 (s, 6H; NACTHUNGTRENNNUG

Table 3. (Continued)

C₆H₂Me₃), 2.79 (d, ²J

A

Entry

Alkyne

Indole

Ratio of

t

T

Yield

2

(d, J

(H,H)=12.20 Hz, 2H; CHH), 6.08 (s, 1H; NH), 6.53

regioisomers^[a][h] [8C] [%]

3

(ddd, J(H(5)_py,H(4)_py)=6.5 Hz, J(H(5)_py,H(6)_py)=6.5 Hz,

⁴J(H(5)_py,H(3)_py)=1.0 Hz, 1H; H(5)_py), 6.70 (t, ³J-

AHCTUNGTRENNUNG

(H_p,H_o)=6.5 Hz, 2H; H_p), 6.82 (d, ³J(H(3)_py,H(4)_py)=

8.1 Hz, 1H; H(3)_py), 6.90 (s, 2H; C₆H₂Me₃), 6.97 (t, ³J-

(H_m,H_o)=6.5 Hz, ³J

(H_m,H_p)=6.5 Hz, 4H; H_m), 7.02 (dt,

³J(H(4)_py,H(3)_py)=7.9 Hz, ³J(H(4)_py,H(5)_py)=7.9 Hz,

A

ACHTUNGTRENNUNG

⁴J(H(4)_py,H(6)_py)=1.8 Hz, 1H; H(4)_py), 7.04 (s, 2H;

C₆H₂Me₃), 8.20 ppm (dd, ³J(H(6)_py,H(5)_py)=5.3 Hz,

⁴J(H(6)_py,H(4)_py)=1.2 Hz, 1H; H(6)_py); ¹³C {¹H} NMR

Ind7

–

24 RT 11

(C₆D₆, 150 MHz, 296 K): d=18.0 (q, C₆H

(q, C₆H₂A(CH₃)₃), 20.9 (q, C₆H₂A(CH₃)₃), 24.5 (q, CH₃), 39.7

(q, N(CH₃)₂), 46.3 (s, CCH₃), 66.6 (t, CH₂), 117.9 (d, C_o),

₂ACHTUNGERTN(NUNG CH₃)₃), 18.4

C

CHTUNGTRENNUNG

AHCTUNGTRENNUNG

118.7 (d, C_p), 120.2 (d, C(3)_py), 122.0 (d, C(5)_py), 128.5 (d,

C_m), 129.4 (d, m-C₆H₂Me₃), 130.0 (d, C(4)_py), 133.1, 134.3

(d, o,p-C₆H₂Me₃), 147.4 (d, C(6)_py), 147.9 (s, NC₆H₂Me₃),

149.8 (s, NC₆H₅), 162.8 ppm (s, C(2)_py); ¹⁵N NMR

(60 MHz, C₆D₆, 296 K): d=165.6 (NMe₂), 177.5

(NC₆H₂Me₃), 189.0 (N_aH), 289.0 ppm (l-N_py); IR (Nujol,

NaCl): n˜ =3263 (w), 3057 (w), 2924 (s), 2854 (s), 2761 (w),

1577 (m), 1465 (s), 1376 (m), 1301(m), 1224 (m), 1094

(w), 1024 (w), 935 (m), 851 (w), 800 (w), 743 (m),

691 cm^ꢀ1(w); elemental analysis calcd (%) for

C₄₁H₅₀N₆Zr: C 68.58, H 7.02, N 11.70; found: C 68.60,

H 7.04, N 11.86.

Ind8

>9:1^[b]

24 80 70

Preparation of [ZrACTHNUGTRENNG{U (NTBS)₂N_py}ACHTUNTGRNE(NUGN HNNPh₂)₂] (4a): The

Ind9

5:1^[b]

24 80 44

formation of compound 4a in the reaction of the metalla-

cycles with diphenylhydrazine was confirmed by compari-

son of the spectra to an authentic sample, which was pre-

pared as follows: To

a stirring solution of [Zr-

A

}ACHTUNGTRENNUNG

ene (20 mL) was added a solution of diphenylhydrazine

(49.6 mg, 0.27 mmol) in toluene (5 mL). The mixture was

stirred overnight at RT, filtered, and the volatile com-

pounds were removed under reduced pressure. [Zr-

1

[a] Determined by H NMR spectroscopy. [b] Major isomer shown.

Table 4. Catalytic indole synthesis of various diarylhydrazines with 2-butyne.

A

}ACTHUNGTRENNU(G HNNPh₂)₂] was obtained in quantitative

Entry

Hydrazine

Indole

Ratio of

t

T

Yield

1

regioisomers^[a][h] [8C] [%]

AHCTUNGTRENNUNG

A

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

Ind10

3:2^[b]

24

80

43

52

⁴J(H(5)_py,H(3)_py)=0.9 Hz, 1H; H(5)_py), 6.82–6.87 (m, 3H;

H(3)_py, p-H_PhA), 6.90 (t, J(p-H_ph,m-H_ph), 2H; p-H_PhB), 7.00

(dt, ³J(H(4)_py,H(3)/H(5)_py)=7.8 Hz, ⁴J(H(4)_py,H(6)_py)=

1.5 Hz, 1H; H(4)_py), 7.17–7.23 (m, 8H; m-H_PhA, m-H_PhB),

7.31 (d, ³J(o-H_ph,m-H_ph)=8.6 Hz, 4H; o-H_PhB), 7.50 (d,

³J(o-H_ph,m-H_ph)=8.5 Hz, 4H; o-H_PhA), 9.15 ppm (dd,

Ind11

Ind12

–

³J(H(6)_py,H(5)_py)=5.5 Hz,

⁴J(H(6)_py,H(4)_py)=0.9 Hz,

H(6)_py), ¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=ꢀ4.2,

ꢀ4.0 (Si

ACHUTNGTNERNU(G CH₃)₂), 20.4 (SiCCAHTUNTGREN(NGUN CH₃)₃), 24.7 (CCH₃), 27.7

(SiCCATHGUNENRT(UNG CH₃)₃), 47.8 (CCH₃), 63.6 (CH₂), 120.5 (o-C_PhA),

121.1 (p-C_PhA, C(3)_py), 121.3 (C(5)_py), 121.6 (o-C_PhB), 122.3

(p-C_PhB), 128.9 (m-C_PhA), 129.0 (m-C_PhB), 138.3 (C(4)_py),

147.2 (C(6)_py), 151.1 (i-C_PhA), 152.3 (i-C_PhB), 161.6 ppm

(C(2)_py); ²⁹Si {¹H} NMR (80 MHz, C₆D₆, 296 K): d=

>9:1^[b]

24 RT

15

3.11 ppm (Si

296 K): d=112.6 (NPh_2B), 115.3 (NPh_2A), 174.9 (NSi-

(CH₃)₂tBu), 192.7 (NH), 194.6 (NH), 291.6 (LN_py); IR

(CH₃)₂tBu); ¹⁵N NMR (60 MHz, C₆D₆,

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

1

[a] Determined by H NMR spectroscopy. [b] Major isomer shown.

(Nujol, NaCl): n˜ =3242 (w), 3189 (w), 1931 (w), 1587 (s),

1466 (s), 1377 (m), 1310 (w), 1254 (m), 1168 (w), 1087

(sh), 1050 (s), 864 (s), 829 (s), 769 (m), 748 (s), 693 (m),

666 cm^ꢀ1(w); elemental analysis calcd (%) for

C₄₅H₆₃N₇Si₂Zr·0.5C₇H₈: C 65.05, H 7.54, N 10.97; found: C 65.10, H 7,73,

for 1 day, the solution was filtrated and the volatile compounds were re-

N 10.52.

moved under reduced pressure to yield [Zr

(NMe₂)] as a yellow solid. Yield 0.38 g (0.53 mmol, 62%); ¹H NMR

(600 MHz, C₆D₆, 296 K): d=1.01 (s, 3H; CH₃), 1.71 (s, 6H; C₆H₂Me₃),

ACHTUNGTREN{NUG (NMes)₂N_py}ACHTUNGTERN(NUGN NHNPh₂)-

ACHTUNGTRENNUNG

NMR-scale preparation of [Zr

tion of compound 4 in the reaction of the metallacycles with diphenylhy-

ACHTUTNGNERUNG{(NMes)₂N_py}AHCUTNGTREN(NUGN HNNPh₂)₂] (4): The forma-

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Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

pentane (3 mL) to yield [ZrACTHNUGTRNEN{UNG (NXyl)₂N_py}ACHTUNTGENRN(GU NNMePh)CAHTUGTNRENNUG(dmap)₂] as red nee-

dles. Yield: 43.00 mg (52.0 mmol, 42%). Single-crystal X-ray analysis was

obtained from these needles at RT. ¹H NMR (600 MHz, [D₈]THF,

296 K): d=1.83 (s, 12H; CH₃(xylyl)), 2.91–2.96 (m, 12H; CH₃(dmap)),

3.17 (s, 3H; NNCH₃), 3.31 (d, ²J

(H,H)=11.9 Hz, 1H; CHH), 3.51 (d, ²J

3.35–3.66 (m, 1H; CHH overlay with residual solvent signal), 5.77 (s,

2H; H_p-Xyl), 6.13 (t, ³J

(H_p,H_m)=7.1 Hz, 1H; p-ArH), 6.44–6.50 (m, 4H;

CHCNMe₂, coordinated dmap overlay with uncoordinated dmap), 6.63

ACHTUNGTRENNUNG

A

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

(s, 4H; H_o-Xyl), 6.75 (t, ³J

ACHTNUTRGEN(UNG H_m,H_o/H_p)=7.4 Hz, 2H; H_m), 6.86–6.91 (m,

3H; H(5)_py, o-ArH), 7.53 (d, ³J(H(6)_py,H(5)_py)=5.2 Hz, 1H; H(6)_py), 7.80

(t, ³J(H(4)_py,H(5)_py)=7.4 Hz, 1H; H_4py), 7.82–7.87 (m, 1H; H(3)_py),

8.20 ppm (d, ³J

ACHTUNGTRENNUNG

Figure 5. Molecular structure of indole Ind12.

AHCTUNGTRENNUNG

(NNCH₃), 62.6, 63.4 (CH₂), 106.2 (CHCNMe₂, dmap), 108.7, 120.6

(C(5)_py, C_o-Ar), 111.4 (C_p-Ph), 112.7 (o-C₆H₃Me₂), 113.6 (C_o-Ph), 114.9 (p-

C₆H₃Me₂), 127.0 (C_m-Ph), 134.8 (m-C₆H₃Me₂), 138.2 (C(4)_py), 138.6

(C(3)_py), 147.1 (C(6)_py), 147.2 (NPh), 147.9 (C(2)_py); 149.8 (NC₆H₃Me₂),

150.0 (CNMe₂, dmap), 152.0 ppm (NCH, dmap); IR (Nujol, NaCl): n˜ =

2924 (s), 2854 (s), 2601 (w), 1599 (m), 1463 (s), 1377 (m), 1260 (m), 1190

(w), 1090 (m), 1015 (m), 801 (m), 721 cm^ꢀ1(w); elemental analysis calcd

(%) for C₄₈H₆₁N₉Zr: C 66.79, H 6.95, N 15.24; found: C 67.06, H 7.08,

N 15.34.

Preparation of [Zr

ACHTGNUNRET{NUNG (NXyl)₂N_py}CAHUTNGTERNNGU(NNPh₂)ACHTNUEGRTG(NNUN dmap)₂] (6): [ZrACHTNGURTEN{NUGN (NXyl)₂N_py}-

AHCTUNGTRENNUNG

(33.25 mg, 27.23 mmol), and 1,1-diphenylhyadrazine (16.75 g, 90.93 mmol)

were dissolved in toluene (10 mL). After standing at RT for 1 d, a red

solid precipitated as thin needles. The solvent was removed by filtration

and the crude product was washed with pentane (10 mL) to yield [Zr-

AHCTNUGTRENUN{GN (NXyl)₂N_py}ACHTUNRTGEG(NUNN NNPh₂)ACHTNUGERTN(NUGN dmap)₂] as red needles. Yield 56.80 mg

(64.01 mmol, 67%). Single-crystal X-ray analysis was obtained from these

needles at RT. ¹H NMR (600 MHz, C₆D₆, 296 K): d=1.45 (s, 3H; CH₃),

2

2.11 (s, 12H; CH₃(dmap)), 2.31 (s, 12H; CH₃(Xylyl), 3.61 (d, J

N

12.3 Hz, 2H; CHH), 3.91 (d, ²J

(H,H)=6.8 Hz, 1H; H(3)_py), 5.89, 6.17 (s, 2H; H_p-Xyl) (brs, 4H; dmap),

6.41 (brs, 4H; (H_p,H_o)=

_o-Xyl), 6.72 (tt, 7.01 ³J(H_p,H_m)=7.3 Hz, ²J

1.0 Hz, 2H; p-ArH), 6.75–6.78 (m, 1H; H(4)_py), 6.98 (t, ³J

(H_m,H_o)=

7.3 Hz, ³J

(H_m,H_p)=7.3 Hz, 4H; m-ArH), 7.12 (m, 1H; H(5)_py), 7.20 (dd,

³J(H_o,H_m)=8.6 Hz, ⁴J

(H_o,H_p)=1.1 Hz, 4H; o-ArH), 7.98 (d,

(H,H)=12.3 Hz, 2H; CHH), 5.71 (d, ²J-

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

H

A

ACHTUNGTRENNUNG

Scheme 9. Proposal of a mechanistic cycle for the catalytic formation of

indoles from 1,2-diarylhydrazines and alkynes.

AHCTUNGTRENNUNG

N

ACHTUNGTRENNUNG

³J(H(6)_py,H(5)_py)=7.7 Hz, 1H; H(6)_py), 8.31 ppm (brs, 4H; dmap);

¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=22.2 (CH₃(Xylyl)), 26.6

(CH₃), 38.9 (CH₃(dmap)), 45.9 (CCH₃), 62.5 (CH₂), 10.5.9, 106.3 (dmap,

C(3)_py), 114.0 (p-C₆H₃Me₂), 116.9 (o-C₆H₃Me₂), 119.4 (C(5)_py), 120.4,

120.5 (C(6)_py, C(4)_py), 121.2, 121.3 (C_m-Ph, C_o-Ph), 127.9 (C_o-Ph), 136.5 (m-

C₆H₃Me₂), 138.2 (dmap), 152.5, 155.1 (NPh2, NC₆H₃Me₂), 165.4 ppm

(C(2)_py); IR (Nujol, NaCl): n˜ =3061 (w), 2924 (s), 2854 (s), 1613 (s), 1577

(m), 1533 (m), 1464 (s), 1377 (m), 1317 (m), 1296 (m), 1260 (m), 1226

(m), 1099 (w), 1004 (m), 941 (w), 812 (s), 697 cm^ꢀ1(w); elemental analy-

sis calcd (%) for C₅₁H₅₉N₉Zr: C 68.88, H 6.69, N 14.18; found: C 68.98,

H 6.80, N 13.96.

drazine was confirmed by comparison with an authentic sample, which

was prepared as follows: To a solution of [ZrACHTUNRGTENNG{U (NMes)₂N_py}ACHTUNTGREN(NUGN NMe₂)₂]

(10.00 mg, 0.02 mmol) in C₆D₆were added two equivalents of diphenyl-

hydrazine (6.40 mg, 0.04 mmol). The reaction mixture was heated to

808C for 3 d. Analysis by NMR spectroscopy indicated the formation of

the title compound and a small quantity of [Zr

ACHTUNGTREN{NUG (NMes)₂N_py}ACHTUNGTERN(NUGN NHNPh₂)-

ACHTUNGTRENNUNG

complete conversion into the bis-hydrazido complex was observed.

¹H NMR (600 MHz, C₆D₆, 296 K): d=0.98 (s, 3H; C_MesH₃), 1.53 (s, 6H;

o-CH₃), 2.31 (s, 6H; p-CH₃), 2.61 (brs, 6H; o-CH₃), 2.78 (d, ³J

ACHTUNGTRENNUNG

12.1 Hz, 2H; CH₂), 3.56 (d, ³J

ACHTUNGTRENNUNG

Preparation of [Zr

ACHTUTGNRNENUG{(NTBS)₂N_py}ACHTGNUTRENNUNG

NH), 6.37 (brs, 1H; NH), 6.56 (t, ³J(H(5)_py,H(4)_py)=6.5 Hz,

³J(H(5)_py,H(6)_py)=6.2 Hz, 1H; H(5)_py), 6.72 (t, ³J(p-H_Ph,m-H_Ph)=7.4 Hz,

4H; H_p-Ph), 6.78 (d, ³J(H(3)_py,H(4)_py)=8.1 Hz, 1H; H(3)_py), 6.83 (s, 2H;

2ꢃHL_Mes), 6.85–7.02 (m, 16H; H(4)_py, H_o-Ph, H_m-Ph), 7.02–7.06 (m, 3H; 2ꢃ

To stirring solution of [Zr

a

N

ACHTUNGTRENNUNG

0.54 mmol) in toluene (20 mL) was added a solution of 2-butyne (48 mL,

0.54 mmol) in toluene (2 mL). The reaction mixture was stirred for 8 h at

RT, filtered, and the volatile compounds were removed under reduced

pressure. The resulting orange solid was extracted with pentane (3ꢃ

10 mL) and the combined extracts were dried in vacuo to yield 120 mg

HL_Mes, H_o-Phor H

_m-Ph), 9.22 ppm (d, ³J(H(6)_py,H(5)_py)=5.8 Hz, 1H;

H(6)_py); ¹³C NMR (150 MHz, C₆D₆, 296 K): d=18.3 (o-CH₃), 18.6 (o-

CH₃), 21.1 (p-CH₃), 24.5 (CCH₃), 46.6 (CCH₃), 65.8 (CH₂), 119.3 (C_o-Ph),

120.3 (C(3)_py), 122.4 (C(5)_py), 128.4, 128.6 (C_o-Ph, C_m-Ph), 129.8, 129.9

(C_MesH), 133.5, 134.5, 135.3 (CCH₃), 139.4 (C(4)_py), 147.1 (NC_Mes), 147.9

(C(6)_py), 162.3 ppm (C(2)_py); ¹⁵N NMR (60 MHz, C₆D₆, 296 K): d=186.9

(N-CH₂-L), 284.3 ppm (N_py) (NH not observed).

(32%) of [ZrACHTUNGTRNEU{GN (NTBS)₂N_py}{(Ph)NC₆H₄(Me)C=C(Me)NH}] as an orange

solid. ¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.37, ꢀ0.26, 0.11, 0.40 (s,

3H; Si

ACHUTNGTNERN(UG CH₃)₂), 0.80, 1.06 (s, 9H; SiCACHUTNGTRENN(NGU CH₃)₃), 1.09 (s, 3H; CH₃), 1.91 (s,

3H; HNCACTHNUGTREN(NUNG CH₃)), 2.26 (s, 3H; ArCCAHTUNGTRENNUGN

(CH₃)) 3.33, 3.52, 3.85, 3.95 (d, ²J-

AHCTUNGTRENG(UNN H,H)=12.4 Hz, 1H; CH₂), 5.46 (brs, 1H; NH) 6.46 (ddd,

³J(H(5)_py,H(4)_py)=7.7 Hz, ³J(H(5)_py,H(6)_py)=5.4 Hz, ⁴J(H(5)_py,H(3)_py)=

Preparation of [Zr

(NMe₂)₂] (68.00 mg, 0.12 mmol, see the Supporting Information), DMAP

(45.30 mg, 0.37 mmol), and methylphenylhydrazine

ACHTUNGTRENNUNG{(NXyl)₂N_py}ACHUTTGNRENNUG(NNMePh)ACHTNUEGRTG(NUNN dmap)₂] (5): [ZrACHNUTGTRENNUNG

3

ACHTUNGTRENNUNG

1.1 Hz, 1H; H(5)_py), 6.63 (d, J(o-H_Ph,m-H_Ph)=8.0 Hz, 2ꢃH o-H_NPh), 6.54

(t, ³J(p-H_NPh,m-H_NPh)=7.3 Hz, 1H; p-H_NPh), 6.82 (d, ³J(H(3)_py,H(4)_py)=

8.0 Hz, 1H; H(3)_py), 6.95 (dt, ³J(H(4)_py,H(3)/H(5)_py)=8.0 Hz,

⁴J(H(4)_py,H(6)_py)=1.7 Hz, 1H; H(4)_py), 7.13 (t, ³J(m-H_NPh,o/p-H_NPh)=

0.12 mmol) were dissolved in toluene (3 mL). After standing at RT under

reduced pressure for 1 d, a red solid precipitated as thin needles. The sol-

vent was removed by filtration and the crude product was washed with

8.0 Hz, 2H; m-H_NPh), 7.17 (dt, ³J(H_Ar,H_Ar)=7.8 Hz, ⁴J

ACHTNUGRTENNUG AHCUTNGTREN(NGUN H_Ar,H_Ar)=1.6 Hz

Chem. Eur. J. 2012, 18, 3925 – 3941

ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3935

L. H. Gade et al.

1H; H_Ar), 7.25 (dt, ³J

G

E

6.88–6.97 (m, 5H; m-H_CCPhA, m-H_CCPhB, H(4)_py), 6,99–7.09 (m, 3H; p-

H_CCPhA, p-H_CCPhB, H_Ar), 7.15 (sub-C₆D₆, 1H; H_Ar), 7.18–7.26 (m, 4H; m-

3

4

3

7.29 (dd, J

A

(H_Ar,H_Ar)=7.8 Hz, J

(H_Ar,H_Ar)=7.8 Hz, ⁴J

H_NPh, o-H_CCPhB), 7.34–7.43 (m, 3H; o-H_NPh, H_Ar), 7.47 (d, ³J

ACTHUNGTREN(NUG H_Ar,H_Ar)=

³J(H(6)_py,H(5)_py)=5.5 Hz, ⁴J(H(6)_py,H(4)_py)=1.6 Hz, 1H; H(6)_py);

7.8 Hz, 1H; H_Ar), 9.07 ppm (d, ³J(H(6)_py,H(5)_py)=4.0 Hz, 1H; H(6)_py);

¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=ꢀ4.7, ꢀ4.3, ꢀ4.1, ꢀ1.8 (Si-

¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=ꢀ1.7, ꢀ4.2, ꢀ4.1, ꢀ2.7 (Si-

A

R

ACTHGNUTERN(UNGN CH₃)₂), 20.4, 20.7 (SiCACHTUNRTEGN(GNUN CH₃)₃), 25.2 (CCH₃), 28.0, 28.4 (SiCCAHTNUGTREN(GUNN CH₃)₃)_,49.6

A

N

(CCH₃), 62.9, 63.2 (CH₂), 115.0 (C=C), 117.5 (o-C_NPh), 120.6 (C(3)_py),

122.2 (C(5)_py), 124.9, 126.0, 126.3, 127.5, 127.7, 127.9 (C_Ar, C_Ar, m-C_PhA,

N

(C(5)_py), 126.3 (C_Ar), 127.0 (C_Ar), 129.2 (m-C_NPh), 130.9 (C_Ar), 131.3 (C_Ar),

139.8 (C(4)_py), 141.5 (C_Ar), 142.5 (C_Ar), 147.6 (C=C(Me)Ar), 149.2

(C(6)_py), 153.7 (i-C_NPh), 162.6 ppm (C(2)_py); ²⁹Si {¹H} NMR (80 MHz,

m-C_PhB, p-C_PhA, p-C_PhB), 129.2, 129.3 (m-C_NPh, o-C_PhB), 131.7 (C_Ar), 133.7

(o-C_PhA), 135.5 (C_Ar), 139.8 (C(4)_py), 143.0, 146.1 (2-C_Ar), 146.7 (i-C_PhA),

146.9 (C=C), 149.0 (C(6)_py), 150.5 (i-C_PhB), 144.5 (i-C_NPh), 162.6 ppm

(C(2)_py); ²⁹Si {¹H} NMR (80 MHz, C₆D₆, 296 K): d=3.29, 3.88 ppm (Si-

C₆D₆, 296 K): d=3.29, 3.88 ppm (Si

C₆D₆, 296 K): d=174.2, 180.0 (N-Si(CH₃)₂tBu), 190.1 (NH), 199.8 (NPh₂),

(CH₃)₂tBu); ¹⁵N NMR (60 MHz,

ACHTUNGTRENNUNG

G

(CH₃)₂tBu); ¹⁵N NMR (60 MHz, C₆D₆, 296 K): d=177.6, 185.9 (NSi-

ACHTUNGTRENNUNG

281.2 ppm (LN_py); IR (Nujol, NaCl): n˜ =3051 (w), 2725 (w), 2672 (w),

1602 (m), 1463 (s), 1377 (s), 1342 (w), 1291 (m), 1260 (m), 1199 (w), 1089

(w), 1034 (m), 908 (m), 891 (m), 852 (s), 828 (m), 799 (w), 780 (w), 721

(m), 666 cm^ꢀ1(w); elemental analysis calcd (%) for C₃₇H₅₇N₅Si₂Zr:

C 61.78, H 7.99, N 9.74; found: C 62.02, H 7.96, N 9.59.

ACTHGNUERTN(NUNG CH₃)₂tBu), 190.3 (NH), 201.2 (NPh₂), 279.3 ppm (LN_py); IR (Nujol,

NaCl): n˜ =3290 (m), 2733 (w), 2681 (w), 1592 (s), 1466 (s), 1378 (s), 1260

(w), 1136 (w), 1110 (m), 1087 (m), 1033 (s), 936 (m), 908 (s), 890 (s), 854

(m), 775 (w), 723 (m), 698 (w), 667 (w), 629 cm^ꢀ1(w); elemental analysis

calcd (%) for C₄₇H₆₁N₅Si₂Zr: C 66.93, H 7.29, N 8.30; found: C 67.20,

H 7.41, N 8.19.

Preparation of [Zr

To stirring solution of [Zr

0.27 mmol) in toluene (20 mL) was added

ACHTUNGTRENNUNG{(NTBS)₂N_py}ACHTGNUTRENNUNG

a

G

U

Preparation of [Zr

Ph)NH}] (7d): To a stirring solution of [Zr

(200 mg, 0.27 mmol) in toluene (20 mL) was added a suspension of bisACHTUNGTRENNUNG

A

E

N

ACHTUNGTRENNUNG(4-Br-

A

}ACHTUNGTRENNUNG

(22.6 mg, 0.27 mmol) in toluene (1 mL). The reaction mixture was stirred

for 8 h at RT, filtered, and the volatile compounds were removed under

reduced pressure. [ZrACHTUNGTRENNUNG{(NTBS)₂N_py}{(Ph)NC₆H₄(Et)C=C(Et)NH}] was ob-

bromo)phenylacetylene (90 mg, 0.27 mmol) in toluene (5 mL). The reac-

tion mixture was stirred for 4 h at RT, filtered, and the volatile com-

pounds were removed under reduced pressure. The crude product was re-

tained in quantitative yield as an orange solid. Single crystals suitable for

X-ray diffraction were grown from a saturated solution in toluene at RT.

¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.43, ꢀ0.32, 0.16, 0.4 (s, 3H; Si-

crystallized from n-hexane at ꢀ208C. [Zr

ACHTUGTNRNENUG{(NTBS)₂N_py}{(Ph)NC₆H₄ACHTUNGTRENNUNG(4-Br-

Ph)C=CACTHNURTGNEU(GN 4-Br-Ph)NH}] was obtained as a yellow solid. Yield: 180 mg

A

E

U

(60%); ¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.28, ꢀ0.19, ꢀ0.06,

A

U

ꢀ0.09 (s, 3H; Si

ACHTGNUERTN(NUGN CH₃)₂), 0.77 (s, 9H; SiCAHCTUNRGTENN(GNU CH₃)₃), 0.90 (s, 9H; SiCACHTUNGTRENNUNG(CH₃)₃),

A

U

1.04 (s, 3H CH₃), 3.34, 3.42, 3.84, 3.93 (d, ²J

5.94 (brs, 1H; NH), 6.46 (ddd,

³J(H(5)_py,H(6)_py)=5.5 Hz, ⁴J(H(5)_py,H(3)_py)=0.9 Hz, 1H; H(5)_py), 6.72–

6.76 (m, 3H; o-H_NPh

p-H_NPh), 6.78 (d, ³J(H(3),H(4))=8.33 Hz, 1H;

H(3)_py), 6.86 (d, ³J(H_Ar,H_Ar)=8.3 Hz, 2H; H_Ar), 6.91 (dt, ³J(H(4)_py,H(3)/

H(5)_py)=7.9 Hz, ⁴J(H(4)_py,H(6)_py)=1.7 Hz, 1H; H(4)_py), 7.00, 7.43 (d, ³J-

(H_Ar,H_Ar)=8.3 Hz, 2H; H_Ar), 7.06–7.08 (m, 1H; H_Ar), 7.11 (d, ³J-

(H_Ar,H_Ar)=8.3 Hz, 2H; H_Ar), 7.19 (t, ³J(m-H_Ph,o/p-H_Ph)=8.1 Hz, 2H; m-

H_NPh), 7.15–7.17 (m, 1H; H_Ar), 7.30 (dd, ³J(H_Ar,H_Ar)=8.0 Hz, ⁴J-

(H_Ar,H_Ar)=1.6 Hz, 1H; H_Ar), 7.34 (dd, ³J(H_Ar,H_Ar)=8.0 Hz, ⁴J-

(H_Ar,H_Ar)=1.2 Hz 1H; H_Ar), 9.01 ppm (dd, ³J(H(6)_py,H(5)_py)=5.5 Hz,

⁴J(H(6)_py,H(4)_py)=1.3 Hz, H(6)_py); ¹³C {¹H} NMR (150 MHz, C₆D₆,

296 K): d=ꢀ4.8, ꢀ4.2, ꢀ4.1, ꢀ1.9 (Si(CH₃)₂), 20.3, 20.7 (SiC(CH₃)₃), 25.1

(CCH₃), 27.9, 28.4 (SiC(CH₃)₃)_,49.5 (CCH₃), 62.8, 63.1 (CH₂), 113.5

(HNC(Ar-p-Br)), 117.0 (o-C_NPh), 117.3 (p-C_NPh), 119.1 (C(3)_py), 120.1

ACHTUNGTRENNUNG

A

ACHTUNGTRENNUNG

2

3.84, 3.99 (d, J

G

,

³J(H(5)_py,H(4)_py)=7.6 Hz, ³J(H(5)_py,H(6)_py)=5.4 Hz, ⁴J(H(5)_py,H(3)_py)=

AHCTUNGTRENNUNG

1.1 Hz, 1H; H(5)_py), 6.64–6.73 (m, 3H; o-H_NPh

, p-H_NPh), 6.82 (d,

³J(H(3),H(4))=8.1 Hz, 1H; H(3)_py), 6.95 (dt, ³J(H(4)_py,H(3)/(5)_py)=

7.9 Hz, ⁴J(H(4)_py,H(6)_py)=1.8 Hz, 1H; H(4)_py), 7.12 (m, 2H; m-H_NPh),

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

7.17 (m, 2H; H_Ar), 7.35 (dd, ³J

1H; H_Ar), 7.61 (dd, ³J

N

G

ACHTUNGTRENNUNG

E

G

R

ACHTUNGTRENNUNG

H(6)_py); ¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=ꢀ5.0, ꢀ4.3, ꢀ4.2,

ꢀ3.4 (Si

N

U

ACHTUNGTRENNUNG

T

N

ACHTUNGTRENNUNG

(CH₂CH₃-A), 49.5 (CCH₃), 62.7, 63.5 (CH₂), 112.7 (HNC(Et)), 116.8 (o-

C_NPh), 117.5 (p-C_NPh), 120.5 (C(3)_py), 122.0 (C(5)_py), 125.8 (C_Ar), 127.1

(C_Ar), 129.0 (m-C_NPh), 131.2 (C_Ar), 132.3 (C_Ar), 139.6 (C(4)_py), 143.4 (C_Ar),

146.1 (C_Ar), 147.2 (C=C(Et)Ar), 148.9 (C(6)_py), 154.4 (i-C_NPh), 162.6 ppm

(C(2)_py); ²⁹Si {¹H} NMR (80 MHz, C₆D₆, 296 K): d=3.27, 3.76 ppm (Si-

ACHTUNGTRENNUNG

(C(5)_py), 120.6 (C_Ar), 122.3 (C_Ar), 126.5 (m-C_NPh), 127.9 (C_Ar), 129.4 (C_Ar),

130.8 (C_Ar), 130.9 (C_Ar), 131.3 (C_Ar), 135.3 (C_Ar), 140.2 (C(4)_py), 143.1 (C=

CACHTUNGTRENNUNG

A

E

ACHTUNGTRENNUNG

A

R

ACHTUNGTRENNUNG

NaCl): n˜ =3192 (w), 2900 (s), 2727 (w), 2032 (w), 1600 (m), 1464 (s), 1377

(s), 1340 (w), 1260 (m), 1194 (w),1110 (m), 1087 (m), 1030 (s), 909 (m),

890 (m), 860 (s), 828 (m), 801 (w), 774 (m), 748 (w), 727 (m), 694 (w),

667 cm^ꢀ1(w); elemental analysis calcd (%) for C₃₉H₆₁N₅Si₂Zr·0.5C₇H₈:

C 64.34, H 8.26, N 8.83; found: C 64.59, H 8.34, N 8.45.

201.1 (NPh₂), 278.9 ppm (LN_py); IR (Nujol, NaCl): n˜ =3289 (w), 2854 (s),

2054 (w), 1596 (s), 1464 (s), 1377 (s), 1296 (w), 1250 (m), 1121 (w), 1078

(w), 1030 (m), 854 (m), 829 (m), 774 (m), 748 (m), 723 (w), 666 cm^ꢀ1(w);

elemental analysis calcd (%) for C₄₇H₅₉N₅Br₂Si₂Zr: C 56.38, H 5.94,

N 6.99; found: C 56.35, H 5.96, N 7.00.

Preparation of [Zr

{(NTBS)₂N_py}

R

Preparation of [Zr

and regioisomer [Zr

(7e’): To a stirring solution of [Zr

0.27 mmol) in toluene (20 mL) was added a solution of 1-phenyl-1-pro-

pyne (31.2 mg, 0.27 mmol) in toluene (1 mL). The reaction mixture was

stirred for 8 h at RT, filtered, the volatile compounds were removed

under reduced pressure, and the residue was recrystallized from cold

G

ACHTUNGTRENNUNG

To stirring solution of [Zr

a

G

T

N

ACHTUNGTRENNUNG

0.27 mmol) in toluene (20 mL) was added a solution of diphenylacetylene

(48 mg, 0.27 mmol) in toluene (5 mL). The reaction mixture was stirred

for 4 h at RT, filtered, and the volatile compounds were removed under

reduced pressure. The resulting orange solid was washed with pentane

(3ꢃ10 mL) before drying in vacuo to yield 140 mg (60%) of [Zr-

U

ACHTUNGTRENNUNG

A

(ꢀ788C)

pentane.

N(Ph)NC₆H₄C(Me)=C(Ph)NH}]

The

mixture

(7e)

of

and

[Zr

N

}

ACHTUNGTRENNUNG

crystals suitable for X-ray diffraction were grown from a saturated tolu-

ACHTUNGTRENNUNG

ene solution at RT. ¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.24, ꢀ0.14,

N(Ph)NC₆H₄C(Ph)=C(Me)NH}] (7e’) was obtained as an orange solid.

Yield: 168 mg (80%) 7e: ¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.34,

ꢀ0.02, 0.19 (s, 3H; Si

CH₃), 3.37, 3.46, 3.88, 3.97 (d, ²J

ꢀ0.19, 0.12, 0.41 (s, 3H; Si

ACHTUGTNRENNGU(CH₃)₂), 0.81, 1.02 (s, 9H; SiCCAHTUNGTRENNNUG

1H; NH), 6.28 (t, ³J(H(5)_py,H(4)_py)=5.5 Hz, 1H; H(5)_py), 6.75 (t, ³J(p-

H_NPh,m-H_NPh)=6.9 Hz, 1H; p-H_NPh), 6.79–6.87 (m, 3H; H(3)_py, o-H_NPh),

3H; CH₃), 1.91 (s, 3H;HNCAHTCNUGTRENNUNG ACHTUNGTRENNUNG

(CH₃)), 3.34, 3.54, 3.87, 3.98 (d, ²J

3936

www.chemeurj.org

ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2012, 18, 3925 – 3941

Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

3

7.60 (m , 16H; H_Ar), 9.05 ppm (d, ³J(H(6)_py,H(5)_py)=5.4 Hz, H(6)_py);

7.5 Hz, 3H; CH₂CH₃-A), 0.93 (t, JACHTNUGETRNNU(G H,H)=7.5 Hz, 3H; CH₂CH₃-B), 1.00

¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=ꢀ4.9, ꢀ1.5 (Si

(CH₃)₂), 20.6

(s, 3H; CH₃), 1.23 (s, 3H; o-CH₃), 1.57–1.66 (m, 1H; CHHCH₃-A), 2.08

(s, 3H; o-CH₃), 2.17–2.26 (m, 7H; 2 p-CH₃, CHHCH₃-A), 2.35–2.43 (m,

5H; o-CH₃, CHHCH₃-B, CHHCH₃-B), 2.69 (s, 3H; o-CH₃), 2.88, 2.96,

(SiCACHTUNGTRENNUNG(CH₃)₃), 25.3 (C=CCH₃), 28.0, 28.1 (SiCAHCTUTGNRNE(NUGN CH₃)₃)_,49.3 (CCH₃), 62.7,

63.2 (CH₂), 114.2 (C=C

146.8–154.1 (C_Ar), 162.1 ppm (C(2)_py); ²⁹Si {¹H} NMR (80 MHz, C₆D₆,

296 K): d=3.49, 4.08 ppm (Si

(CH₃)₂tBu); ¹⁵N NMR (60 MHz, C₆D₆,

ACHTUNGTRENNUNG(CH₃)), 116.4–145.3 (C_Ar), 146.7 (C=C(Me)Ar),

3.48, 3.90 (d, ²J

ACTHNUGTRNE(NUG H,H)=12.6 Hz, 1H; CH₂), 5.64 (s, 1H; NH), 6.39 (ddd,

N

³J(H(5)_py,H(4)_py)=6.7 Hz, ³J(H(5)_py,H(6)_py)=5.8 Hz, ⁴J(H(5)_py,H(3)_py)=

3

296 K): d=176.1, 183.4 (N-Si

G

1.5 Hz, 1H; H(5)_py), 6.55 (t, J

(H_Ar,H_Ar)=7.1 Hz, 1H; H_Ar), 6.65–6.80 (m,

280.6 ppm (l-N_py); 7e’: ¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.20,

6H; HL_Mes, H_Ar), 6.87 (d, ³J(H(3)_py,H(4)_py)=8.4 Hz, 1H; H(3)_py), 6.93 (s,

1H; HL_Mes), 6.98–7.04 (m, 3H; H(4)_py, 1ꢃHL_Mes, 1ꢃH_Ar), 7.13–7.18 (m,

ꢀ0.18, 0.00, 0.11 (s, 3H; Si

ACHTUGTNRENNGU(CH₃)₂), 0.84, 0.94 (s, 9H; SiCCAHTUNGTRENNNUG

G

3H; CH₃), 2.29 (s, 3H; C=C

(CH₃)), 3.37, 3.39, 3.84, 3.88 (d, ²J

2H; H_Ar), 7.31 (d, ³J

ACHTGUNTERUNN(G H_Ar,H_Ar)=8.0 Hz, 1H; H_Ar), 9.04 ppm (dt,

³J(H(6)_py,H(5)_py)=5.2 Hz, ⁴J(H(6)_py,H(4)_py)=0.8 Hz, 1H; H(6)_py);

¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=13.2 (CH₂CH₃-A), 16.4

(CH₂CH₃-B), 17.3 (o-CH₃), 17.9 (o-CH₃), 18.1 (o-CH₃), 19.4 (o-CH₃),

20.7 (p-CH₃), 20.8 (p-CH₃), 24.6 (CCH₃), 27.5, 27.9 (CH₂CH₃-A,

CH₂CH₃-B), 46.3 (CCH₃), 66.2, 66.3 (CH₂), 109.2 (HNC(Et)), 117.2

(CH_Ar), 117.3 (CH_Ar), 121.1 (C(3)_py), 122.4 (C(5)_py), 126.4 (CH_Ar), 126.5

(CH_Ar), 128.7 (CH_Ar), 129.3 (CH_Ar), 129.4 (C_MesH), 129.5 (C_MesH), 129.7

(C_MesH), 130.0 (C(4)_py), 130.6 (CH_Ar), 131.6 (C_MesH), 132.0 (o-CCH₃),

132.7 (o-CCH₃), 133.5 (p-CCH₃), 134.1 (o-CCH₃), 134.3 (o-CCH₃), 139.4

(CH_Ar), 147.5 (CH_Ar), 147.8 (C(6)_py), 149.1 (NC_Mes), 149.2 (NC_Mes), 150.1

(C_Ar), 153.6 (C_Ar), 161.9 ppm (C(2)_py); ¹⁵N NMR (60 MHz, C₆D₆, 296 K):

d=184.7 (NH), 188.7, 190.5 (NC_MesH₂), 202.9 (NC₆H₅), 283.2 ppm (N_py);

IR (Nujol, NaCl): n˜ =3176 (w), 2961 (s), 2727 (w), 2664 (w), 2610 (w),

1596 (m), 1466 (s), 1377 (s), 1295 (m), 1225 (m), 1152 (w), 1094 (w), 892

(m), 848 (m), 722 (s), 690 cm^ꢀ1(w); elemental analysis calcd (%) for

C₄₅H₅₃N₅Zr: C 71.57, H 7.07, N 9.27; found: C 71.34, H 7.23, N 9.16.

,

G

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

199.9 (NPh₂), 279.8 ppm (LN_py); IR (Nujol, NaCl) (9a+9b): n˜ =3293 (w),

3174 (w), 3056 (sh), 2733 (w), 2680 (w), 2042 (s), 1594 (s), 1488 (sh), 1465

(s), 1377 (s), 1290 (m), 1260 (m), 1248 (m), 1191 (w), 1162 (w), 1135 (w),

1034 (m), 959 (w), 905 (s), 887 (m), 854 (s), 828 (sh), 777 (w), 750 (m),

699 (m), 667 cm^ꢀ1(w); elemental analysis calcd (%) for

C₄₂H₅₉N₅Si₂Zr·0.5C₇H₈: C 66.05, H 7.67, N 8.46; found: C 66.05, H 7.82,

N 8.43.

Preparation of [Zr

(8a): [Zr{(NMes)₂N_py}(NMe₂)₂] (250 mg, 0.43 mmol), 1,1-diphenylhydra-

{k²-N(Ph)NC₆H₄C(Me)=C(Me)NH}]

ACHTUNGTRENNUNG{(NMes)₂N_py}ACHTUGNTRENNUGN

G

Preparation of [Zr

A

ACHTUNGTERN(NUNG p-F-Ph)NC₆H₄C(Me)=C(Me)NH}]

zine (80 mg, 0.43 mmol), and 2-butyne (34 mL, 0.43 mmol) were dissolved

in toluene (15 mL). After stirring the reaction mixture at 808C for 2 days,

the volatile compounds were removed under reduced pressure and the

crude product was washed with pentane (10 mL) to obtain [Zr-

(8c): [Zr{(NMes)₂N_py}ACHTGNURTENNGUN

G

1-phenylhydrazine (69.0 mg, 0.37 mmol), and 2-butyne (27.14 mL,

0.37 mmol) were dissolved in toluene (10 mL). After stirring the reaction

mixture at 808C for 2 days, the volatile compounds were removed under

{(NMes)₂N_py

}

E

reduced pressure to afford [ZrACTHUNGTERNU{NG (NMes)₂N_py}{NACHTUGNTRNEN(UNG p-F-Ph)NC₆H₄C(Me)=

145 mg (47%). Single crystals suitable for X-ray diffraction were grown

from a saturated solution in pentane at RT. ¹H NMR (600 MHz, C₆D₆,

296 K): d=0.99 (s, 3H; CH₃), 1.24 (s, 3H; o-CH₃), 1.42 (s, 3H; (HNC-

C(Me)NH}] in quantitative yield. Analytically pure samples were ob-

tained by washing the yellow solid with pentane (10 mL). ¹H NMR

(600 MHz, C₆D₆, 296 K): d=0.98 (s, 3H; C_MesH₃), 1.29 (s, 3H; o-CH₃),

A

E

1.43 (s, 3H; HNC

ACHTUNGTRENNUG(CH₃)), 1.86 (s, 3H; Ar-CACHTUGNTRENN(UNG CH₃)), 1.95 (s, 3H; o-CH₃),

AHCTUNGTRENNUNG

2.18–2.23 (m, 6H; p-CH₃), 2.38 (s, 3H; o-CH₃), 2.65 (s, 3H; o-CH₃),

3

G

2.85–2.92 (m, 2H; CH₂), 3.50 (d, ³J

ACTHNGUTERN(NUG H,H)=12.8 Hz, 1H; CH₂), 3.87 (d, J-

2

3

G

(H,H)=12.9 Hz, 1H; CHH), 5.68

ACHTUNGRTNEN(UNG H,H)=13.1 Hz, 1H; CH₂), 5.67 (s, 1H; NH), 6.48 (tt, J(H(5)_py,H(4)_py)=

6.6 Hz, ³J(H(5)_py,H(6)_py)=6.1 Hz, ⁴J(H(5)_py,H(3)_py)=1.1 Hz, 1H; H(5)_py),

6.51–6.59 (m, 3H; 2ꢃH_FAr, H_Ar), 6.64–6.72 (m, 4H; 2ꢃHL_Mes, 2ꢃH_Ar),

6.81–6.91 (m, 4H; 1ꢃHL_Mes, 2ꢃH_FAr, H(3)_py), 6.96 (s, 1H; HL_Mes), 7.01 (s,

1H; HL_Mes), 7.05 (tt, ³J(H(4)_py,H(5)/H(3)_py)=8.0 Hz, ⁴J(H(4)_py,H(6)_py)=

AHCTUNGTRENNUNG

⁴J

ACHTUNGTRENNUNG(H,H)=1.2 Hz, 1H; H_Ar), 6.65 (s, 1H; L_Mes), 6.67–6.80 (m, 5H; HL_Mes,

H_Ar), 6.87 (d, ³J(H(3)_py,H(4)_py)=7.9 Hz, 1H; H(3)_py), 6.92 (s, 1H; L_Mes),

6.96–7.00 (m, 1H; L_Mes), 7.03 (dt, ³J(H(4)_py,H(3)_py)=7.9 Hz,

⁴J(H(4)_py,H(6)_py)=1.4 Hz, 1H; H(4)_py), 7.11–7.16 (m, 3H; H_Ar), 7.18 (d,

3

1.1 Hz, 1H; H(4)_py), 9.04 ppm (d, J(H(6)_py,H(5)_py)=5.1 Hz, 1H; H(6)_py);

¹³C NMR (150 MHz, C₆D₆, 296 K): d=17.5 (o-CH₃), 18.1 (o-CH₃), 18.2

³J

(H,H)=7.8 Hz, 1H; H_Ar), 9.07 ppm (d, ³J

E

(o-CH₃), 19.6 (o-CH₃), 20.2 (HNC

(Ar-C(CH₃)), 24.8 (CCH₃), 46.4 (CCH₃), 66.4 (CH₂), 66.5 (CH₂), 103.1

(HNC(CH₃)), 115.1 (CH_FAr), 116.7, 116.8 (CH_Ar),121.4 (C(3)_py), 122.7

ACHTNUGRTEN(NUGN CH₃), 20.8 (p-CH₃), 21.0 (p-CH₃), 23.2

AHCTUNGTRENNUNG

N

ACHTUNGTRENNUNG

A

(C(5)_py), 126.5 (CH_FAr), 128.4, 129.6, 129.7, 130.3, 130.8, 131.2 (C_MesH;

CH_Ar), 131.8, 139.9, 132.8 133.9, 134.2, 134.3 (CCH₃), 137.8 (C_Ar), 139.7

ACHTUNGTRENNUNG

126.4 (CH_Ar), 126.6 (CH_Ar), 128.3 (CH_Ar), 128.8 (C_MesH), 129.5 (CH_Ar),

129.7 (C_MesH), 129.8 (C_MesH), 130.2 (CH_Ar), 131.0 (CH_Ar), 131.1 (C_MesH),

131.8 (o-CCH₃), 131.9 (o-CCH₃), 132.8 (p-CCH₃), 133.7 (p-CCH₃), 134.3

(o-CCH₃), 134.4 (o-CCH₃), 137.7 (C_Ar), 139.6 (C(4)_py), 142.8 (C=

C(Me)Ar), 147.7 (NC_Mes), 148.2 (C(6)_py), 149.5 (NC_Mes), 150.2 (C_Ar), 154.1

(C_Ar), 162.0 ppm (C(2)_py); ¹⁵N NMR (60 MHz, C₆D₆, 296 K): d=189.4,

191.6 (NC_MesH₂), 189.6 (NH), 204.5 (NC₆H₅), 284.0 ppm (N_py); IR (Nujol,

NaCl,): n˜ =2929 (s), 2854 (s), 1596 (w), 1463 (s), 1377 (s), 1303 (w), 1260

(w), 1223 (w), 1150 (w), 1093 (w), 1018 (m), 800 (m), 722 cm^ꢀ1(s); ele-

mental analysis calcd (%) for C₄₃H₄₉N₅Zr: C 71.03, H 6.79, N 9.63; found:

C 70.58, H 6.91, N 9.48.

(C(4)_py), (142.8 Ar-CACHTUGNETR(UNNG CH₃)), 147.3 (C_Ar) 148.0 (C(6)_py), 149.2 (NC_Mes),

150.1 (NC_Mes), 155.7 (C_FAr), 157.3 (C_FAr), 162.0 ppm (C(2)_py); ¹⁵N NMR

(60 MHz, C₆D₆, 296 K): d=189.1 (NCH₂L), 189.3 (NH), 192.7 (NCH₂L),

201.3 (NC₆H₄F), 284.0 ppm (N_py); ¹⁹F NMR (376 MHz, C₆D₆, 296 K): d=

ꢀ128.2 ppm (ptt, ³J

(F,H)=8.8 Hz, ⁴J

ACHUTNGTRENNUG AHCTUNGTRENN(NGU F,H)=4.6 Hz); IR (Nujol, NaCl,):

n˜ =2923 (s), 2853 (s), 1593 (w), 1463 (s), 1377 (s), 1298 (w), 1223 (w),

1150 (w), 1093 (w), 1018 (m), 851 (w), 798 (w), 722 cm^ꢀ1(w); elemental

analysis calcd (%) for C₄₃H₄₈FN₅Zr: C 69.31, H 6.49, N 9.40; found:

C 68.95, H 6.73, N 9.38.

Preparation of [Zr

N

{ k²-N(Ph)NC₆H₃CH₃C(Me)=C(Me)NH}]

ACHTUNGTRENNUNG

(8d): [Zr{(NMes)₂N_py}ACHTGNURTENNGUN

N

Preparation of [Zr

G

N

yl)hydrazine (85.7 mg, 0.43 mmol), and 2-butyne (34 mL, 0.43 mmol) were

dissolved in toluene (15 mL). After stirring the reaction mixture at 808C

for 4 days, the volatile compounds were removed under reduced pressure

and the crude product was washed with pentane (10 mL) to obtain

[Zr({(NMes)₂N_py(NMe₂)₂] (400 mg, 0.69 mmol), 1,1-diphenylhydrazine

A

}ACHTUNGTRENNUNG

(127 mg, 0.69 mmol), and 3-hexyne (79 mL, 0.69 mmol) were dissolved in

toluene (20 mL). After stirring the reaction mixture at 808C for 2 days,

the volatile compounds were removed under reduced pressure. The

crude product was washed with pentane (10 mL) to obtain [Zr-

270 mg of [Zr

yellow solid (85%). ¹H NMR (600 MHz, C₆D₆, 296 K): d=1.08 (s, 3H;

^LCH₃), 1.25 (s, 3H; o-CH₃), 1.46 (s, 3H; (HNC

(CH₃)), 1.94 (s, 3H; Ar-C-

(CH₃)), 2.09 (s, 3H; o-CH₃), 2.14 (s, 3H; C₆H₃CH₃), 2.20–2.23 (m, 6H; p-

{ k²-N(Ph)NC₆H₃CH₃C(Me)=C(Me)NH}] as a

ACHTNUGRTEN{NGNU (NMes)₂N_py}ACHTNUGTRENNNUG

A

}

A

ACHTUNGTRENNUNG

N

ACHTUNGTRENNUNG

Chem. Eur. J. 2012, 18, 3925 – 3941

ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3937

L. H. Gade et al.

CH₃), 2.41 (s, 3H; o-CH₃), 2.68 (s, 3H; o-CH₃), 2.90 (d, ²J

12.3 Hz, 1H; CHH), 2.96 (d, ²J(H,H)=12.6 Hz, 1H; CHH), 3.51 (d, ²J-

(H,H)=12.1 Hz, 1H; CHH), 3.91 (d, J

(s, 1H; NH), 6.46 (ddd, ³J(H(5)_py,H(6)_py)=6.0 Hz, ³J(H(5)_py,H(4)_py)=

6.6 Hz ⁴J(H(5)_py,H(3)_py)=1.4 Hz, 1H; H(5)_py), 6.54 (td, ³J

(H,H)=7.4 Hz,

⁴J

(H,H)=1.2 Hz, 1H; H_Ar), 6.64–6.74 (m, 4H; 2ꢃHL_Mes+2ꢃH_Ar), 6.87–

6.90 (m, 1H; H(3)_py), 6.94–7.06 (m, 5H; 3ꢃH_Ar, 2ꢃHL_Mes, H(4)_py), 7.17

(t, 1H; H_Ar, overlay with C₆D₆), 7.21 (d, ³J

(H,H)=7.9 Hz, 1H; H_Ar),

9.12 ppm (d, ³J(H,H)=5.1 Hz, 1H; H(6)_py); ¹³C NMR (150 MHz, C₆D₆,

296 K): d=17.3 (o-CH₃), 17.9 (o-CH₃), 18.0 (o-CH₃), 19.4 (o-CH₃), 20.2

(Ar-C(CH3), 20.6 (C₆H₃CH₃), 20.6, 20.8 (p-CH₃), 22.8 (HNC(CH₃)), 24.6

(CCH₃), 46.3 (CCH₃), 66.3, 66.4 (CH₂), 102.8 (HNC(CH₃)), 116.1 (CH_Ar),

121.1 (C(3)_py), 122.4 (C(5)_py), 125.9 (CH_Ar), 126.2 (CH_Ar), 126.3 (CH_Ar),

128.6 (CH_Ar), 129.3 (CH_Ar), 129.5 (CH_Ar), 129.6 (CH_Ar), 129.9 (CH_Ar),

130.8 (CH_Ar), 131.0 (CH_Ar), 131.5 (CH_Ar), 132.7, 133.4, 134.1, 134.2,

134.3, 137.7 (C_q), 139.4 (C(4)_py), 142.5 (C=C(Me)Ar), 148.1 (C(6)_py),

150.1, 151.7 (C_q), 162.0 ppm (C(2)_py); ¹⁵N NMR (60 MHz, C₆D₆, 296 K):

d=187.8 (NH), 189.0, 190.7 (NC_MesH₂), 187.8 (NH), 204.5 (NC₆H₅),

284.1 ppm (N_py); IR (Nujol, NaCl): n˜ =2923 (s), 2853 (s), 2756 (w), 1577

(m), 1464 (s), 1370 (m), 1300 (w), 1223 (w), 1154 (w), 1093 (w), 1025 (w),

934 (m), 851 (m), 802 (w), 782 (w), 743 (m), 691 cm^ꢀ1(w); elemental

analysis calcd (%) for C₄₃H₄₉N₅Zr: C 71.31, H 6.94, N 9.45; found:

C 70.28, H 7.04, N 8.79.

G

(s, 18H; SiC

2.31 (s, 3H;=N

(d, ²J

(H,H)=12.8 Hz, 2H; CHH), 6.57–6.61 (m 3H; H(5)_py, m-H_py), 6.80

E

ACHTUGNERTN(NUNG CH₃)NPh₂),

AHCTUNGTRENNUNG

R

ACHTUNGTRENNUNG

2

G

AHCTUNGTRENNUNG

(d, ³J_H(H(3)_py,H(4)_py)=8.1 Hz, 1H; H(3)_py), 6.83–6.87 (m, 3H; p-H_py, p-

H_Ph), 7.05 (dt, ³J(H(4)_py,H(3)/H(5)_py)=8.1 Hz, ⁴J(H(4)_py,H(6)_py)=1.8 Hz,

1H; H(4)_py), 7.23 (m, 4H; m-H_Ph), 7.65 (m, 4H; o-H_Ph), 9.01 (m, 2 H o-

H_py), 9.78 ppm (dd, ³J(H(6)_py,H(5)_py)=5.3 Hz, ⁴J(H(6)_py,H(4)_py)=1.8 Hz,

H(6)_py); ¹³C {¹H} NMR (150 MHz, C₆D₆, 296 K): d=ꢀ4.2, ꢀ3.0 (Si-

AHCTUNGTRENNUNG

ACHTUNGTRENNUNG

AHCTUNGTRENNUNG

ACHTUNGTRENNUNG

A

R

ACHTNUGTRENN(UGN CH₃)₃), 25.4 (CCH₃, C=C-

A

ACHTUNGTRENNUNG

G

ACHTUNGTRENNUNG

119.7 (p-C_Ph), 120.4 (C(3)_py), 120.5 (o-C_Ph,), 121.0 (C(5)_py), 124.0 (m-C_py),

129.0 (m-C_Ph), 138.3 (C(4)_py), 138.4 (p-C_py), 148.4 (i-C_Ph), 149.5 (C=C),

151.7 (C(6)_py, o-C_py), 160.5 ppm (C(2)_py); ²⁹Si {¹H} NMR (80 MHz, C₆D₆,

AHCTUNGTRENNUNG

296 K): d=0.20 ppm (Si

ACHTUNGTRENNUNG

d=106,7 (NPh₂), 150.0 (NSiAHCTNUGTRENNNUG

340.9 ppm (Zr=N); IR (Nujol, NaCl): n˜ =1585 (w), 1463 (s), 1309 (m),

1260 (w), 1242 (w), 1210 (w), 1088 (m), 1069 (m), 888 (s), 867 (s), 827

(m), 198 (w), 773 (w), 744 (m), 722 (s), 702 (m), 667 cm^ꢀ1(w); elemental

analysis calcd (%) for C₄₂H₆₂N₆Si₂Zr: C 63.18, H 7.83, N 10.53; found:

C 62.60, H 7.88, N 10.81.

Computational studies: The DFT-B3PW91 computational tool was used

to model all the systems with a 6–31 g(d) basis set for C, N, and H

atoms.^[25]An SDD+f function effective core potential basis set^[26]was

used for Zr atoms. All calculations were carried out by using the GAUS-

SIAN03 program package.^[27]Stationary points were verified by frequen-

cy analysis.

Preparation of [Zr

N

ACHTUNGTRENNUNG

stirring solution of [Zr

N

}ACHTUNGTRENNUNG

toluene (20 mL) was added a solution of 2-butyne (48 mL, 0.54 mmol) in

toluene (2 mL). The reaction mixture was stirred for 4 h at RT, filtered,

and the volatile compounds were removed under reduced pressure. The

resulting orange solid was washed with pentane (3ꢃ10 mL) before drying

Crystal structure determination: Crystal data and details of the structure

determinations are listed in Table 5 and Table 6. Preliminary accounts of

the structures of compounds 7b and 8a have been published else-

where.^[11]Full shells of intensity data were collected at low temperatures

(T=100 K) with a Bruker AXS Smart 1000 CCD diffractometer (Mo Ka

radiation, graphite monochromator, l=0.71073 ꢂ). Data were corrected

in vacuo to yield 200 mg (44%) of [ZrACHTUNTGRNNEUG{(NTBS)₂N_py}ACHTUNGTNER(NUNG =NC(Me)=

C(Me)NPh₂)(py)] as an orange solid. Single crystals suitable for X-ray

diffraction were grown from a saturated solution in toluene at RT.

¹H NMR (600 MHz, C₆D₆, 296 K): d=ꢀ0.21, 0.18 (s, 6H; Si

ACHTUGNTRNEN(UNG CH₃)₂), 0.74

Table 5. Single-crystal X-ray diffraction data of compounds 3, 5, 6, 7b, and 7c.

3

5

6

7b

7c

formula

M_r

C₄₁H₅₀N₆Zr

718.09

C₇₀H₈₁N₉Zr

1139.66

C₆₅H_74.50N₉Zr

1073.06

C₄₆H₆₉N₅Si₂Zr

839.46

C₅₃H₆₇N₅Si₂Zr

921.52

crystal system

space group

a [ꢂ]

b [ꢂ]

c [ꢂ]

triclinic

P1

triclinic

P1

monoclinic

P2₁

11.245(6)

15.603(9)

17.233(11)

triclinic

P1

tetragonal

I4₁/a

22.31(1)

¯

10.386(5)

12.711(7)

15.679(7)

112.776(9)

104.416(8)

96.382(7)

1798(2)

2

10.265(5)

12.848(6)

25.954(12)

76.109(7)

83.15(2)

67.129(6)

3060(2)

2

10.803(5)

12.103(5)

18.445(8)

99.28(1)

96.82(1)

103.95(1)

2278(2)

2

38.11(2)

a [8]

b [8]

108.98(2)

g [8]

V [ꢂ³]

Z

2859(3)

2

18960(15)

16

F

G

756

1208

1135

896

7808

]

1.326

1.237

1.246

1.224

1.291

m

G

]

0.344

0.229

0.241

0.330

0.324

max., min. transmission factors

1.0000, 0.8937

0.7464, 0.6781

1.0000, 0.8444

1.0000, 0.9170

1.0000,

0.8461

1.8–27.9

ꢀ20..20,

0..29,

q [8]

1.8–30.5

ꢀ14..14,

ꢀ18..16,

0..22

2.1–32.4

ꢀ15..15,

ꢀ18..19,

0..38

1.9–30.0

ꢀ15..14,

ꢀ21..21,

0..24

1.1–32.3

ꢀ16..15,

ꢀ17..17,

0..27

index ranges (indep. set) h,k,l

0..50

total reflns

unique reflns [R_int

44189

10956 [0.0819]

77649

20256 [0.0506]

67599

16644 [0.0802]

57830

15069 [0.0331]

184687

11307

]

AHCTUNGTRENN[GUN 0.0662]

A

8287

446

1.070

0.0572, 0.1207

0.0861, 0.1324

16050

731

1.029

0.0434, 0.0914

0.0644, 0.1008

13085

750

1.047

0.0534, 0.1089

0.0812, 0.1221

0.04(3)

0.774, ꢀ0.605

12937

557

1.035

0.0368, 0.0871

0.0468, 0.0940

7994

543

1.190

0.0666, 0.1883

0.1034, 0.2194

parameters refined

GOF on F²

R indices [F>4s(F)] R(F), wR(F²)

R indices (all data) R(F), wR(F²)

absolute structure parameter

largest residual peaks [eꢂ^ꢀ3

]

1.616, ꢀ0.716

0.858, ꢀ0.511

1.231, ꢀ0.902

1.394, ꢀ1.066

3938

www.chemeurj.org

ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2012, 18, 3925 – 3941

Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

Table 6. Single-crystal X-ray diffraction data of compounds 8a, 8b, 8c, and Ind12.

8a

8b

8c

Ind12

formula

M_r

C₄₃H₄₉N₅Zr

727.09

C₄₅H₅₃N₅Zr

755.14

C₄₃H₄₈FN₅Zr

745.08

C₁₇H₁₆BrNO

330.22

crystal system

space group

a [ꢂ]

b [ꢂ]

c [ꢂ]

monoclinic

P2₁/n

24.721(10)

12.275(6)

26.305(10)

triclinic

P1

monoclinic

P2₁/n

24.905(4)

12.238(2)

26.308(4)

monoclinic

P2₁/n

13.882(7)

14.936(8)

14.703(7)

¯

12.194(6)

12.461(7)

14.278(7)

69.90(1)

76.51(1)

81.55(1)

1976(2)

2

a [8]

b [8]

110.790(9)

111.508(3)

104.50(1)

g [8]

V [ꢂ³]

Z

7463(6)

8

7460(2)

8

2951(3)

8

F

G

3056

796

3120

1344

]

1.294

1.269

1.327

1.486

m

G

]

0.332

0.316

0.337

2.780

max., min. transmission factors

q [8]

index ranges (indep. set) h,k,l

0.7461, 0.6807

1.0–29.1

ꢀ33..31,

0..16,

0.7464, 0.6367

1.9–30.5

ꢀ16..17,

0..20

47377

12016 [0.0633]

9597

472

1.042

0.0436, 0.0995

0.0636, 0.1095

1.207, ꢀ0.966

0.7452, 0.6747

1.0–25.0

ꢀ29..27,

0..14,

0.8209, 0.6764

1.8–26.4

ꢀ17..17,

ꢀ18..18,

ꢀ18..18

55222

6036 [0.0418]

5272

367

0..36

0..31

total reflns

167231

20058 [0.0917]

14379

909

1.002

0.0426, 0.0796

0.0767, 0.0916

0.553, ꢀ0.506

135180

13138 [0.1299]

8877

927

1.021

0.0576, 0.1069

0.1013, 0.1189

0.963, ꢀ0.610

unique reflns [R_int

]

[Iꢃ2s(I)]

parameters refined

GOF on F²

1.023

R indices [F>4s(F)] R(F), wR(F²)

R indices (all data) R(F), wR(F²)

absolute structure parameter

0.0232, 0.0566

0.0303, 0.0603

0.416, ꢀ0.342

for air and detector absorption, Lorentz and polarization effects;^[28]ab-

sorption by the crystal was treated numerically^[29]or with a semiempirical

multiscan method.^[29–31]

Acknowledgements

The structures were solved by the charge-flip procedure^[32](compounds 3,

7b, 8a–8c, and Ind12), by the heavy-atom method combined with struc-

ture expansion by direct methods applied to difference structure fac-

tors^[33](complex 7c) or by direct methods with dual-space recycling^[34]

(compounds 5 and 6) and refined by full-matrix-least-squares methods

based on F²against all unique reflections.^[35]All non-hydrogen atoms

were given anisotropic displacement parameters. Hydrogen atoms were

generally placed at calculated positions and refined with a riding model.

When justified by the quality of the data, the position of the hydrogen

atom on N(4) was taken from difference Fourier syntheses and refined.

We thank the Deutsche Forschungsgemeinschaft for financial support

(SFB 623, TP A7) and the European Union for the award of a Marie

Curie EIF postdoctoral fellowship (to J.L.F.).

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Domino Reactions of Hydrazinediidozirconium Complexes

FULL PAPER

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Received: November 7, 2011

Revised: January 10, 2012

Published online: February 17, 2012

Chem. Eur. J. 2012, 18, 3925 – 3941

ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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Article Doi

Alternative reaction pathways in domino reactions of hydrazinediidozirconium complexes with alkynes

DOI: 10.1002/chem.201103497

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