Hemilability of the primary amine-metal bond in polyamine-(group 6) metal carbonyl complexes

Journal of Organometallic Chemistry 664 (2002) 214ꢀ222

/

www.elsevier.com/locate/jorganchem

Hemilability of the primary amineꢀ

/

metal bond in polyamine-

(Group 6) metal carbonyl complexes

Anne-Ce´cile Herve´ ^a, Jean-Jacques Yaouanc ^a, Jean-Claude Cle´ment ^a,

Herve´ des Abbayes ^a,ꢁ, Loıc Toupet ^b

´ ´

Laboratoire de Chimie, Electrochimie Moleculaires et Chimie Analytique, UMR CNRS 6521, UFR Sciences et Techniques, Universite de Bretagne

¨

a

Occidentale, 6 Avenue V. Le Gorgeu, BP 809, 29285 Brest Cedex, France

´

b

´ ´

Groupe Matie`re Condensee et Materiaux, UMR CNRS 6626, Universite de Rennes 1, Baˆtiment 11A, 35042 Rennes Cedex, France

Received 17 July 2002; accepted 20 September 2002

Abstract

A series of cis-LM(CO)₄complexes was prepared by reaction of non symmetrical diamines (Lꢂ

and R²ꢂ

alkyl groups) with metal carbonyls M(CO)₆, (MꢂCr, Mo, W). Only the primary amine of these complexes reacted with

mono or dialdehydes, thus leading to mono or dinuclear imine complexes, stabilized by the metal moiety and strongly suggesting

that the NH₂ꢀmetal bond has a hemilabile character.

/

R¹R²Nꢀ

/

(CH₂)_nꢀ

NH₂, with R¹

/

Keywords: Polyamines; Metal carbonyl complexes; Imines; Hemilability

1. Introduction

could be characterized in the absence of the reducing

agent [5].

During the last decade, polyamines, especially sper-

midine and spermine derivatives, have been the subject

of considerable works owing to their potential biological

activities as antimicrobial, antitumoral, DNA transfec-

tion agents for instance [1]. The achievement of new

properties generally requires structural modification of

the polyamine [2] or its stepwise synthesis using the

classical protection/deprotection techniques [3].

We also suspected transient formation of imines in

our systems. Indeed, monoimines 3 (resulting from the

reaction of one equivalent of an aldehyde on complex 1)

were fully characterized [6]. Reaction of two equivalents

of an aldehyde gave diimine complexes 2, isolated as a

mixture of EE, EZ stereoisomers rendering very diffi-

cult the interpretation of ¹H- and ¹³C-NMR spectra

(overlapping signals).

Contrary to tetraamines shown in Scheme 1 which, on

complexation with the metal carbonyl gave a mono-

nuclear complex, spermine gave a dinuclear cis-

L[M(CO)₄]₂complex 4 [7] (Scheme 2), in which all the

amino groups are coordinated, and thus potentially

deactivated towards reaction with aldehydes. Never-

theless, when submitted to the reductive amination,

under the same conditions as for the v,v?-difunctionna-

lization of tetraamines via their fac-LM(CO)₃com-

plexes, terminal amino groups were also selectively

alkylated [8] (Scheme 3). So, coordinated or not, a

terminal primary amino group can react with an

aldehyde. These results suggest that both cis-LM(CO)₄

and fac-LM(CO)₃complexes can transiently liberate

selectively their metal bound primary amino function,

In this context, we recently described the selective

v,v?-N difunctionnalization of linear tetraamines L via

the use of their fac-LM(CO)₃complexes 1 (MꢂCr, Mo,

/

W) involving the reductive amination of aldehydes and

ketones [4] (Scheme 1). This was the first example of the

use of transition metal intermediates in which the metal

is in the zero oxidation state. It must be recalled here

that it has long been known that reductive amination of

ketones is readily catalyzed by cationic transition

metals. It goes through an imine intermediate, which

ꢁ Corresponding author. Tel.: ꢃ

7001

E-mail address: her v e.desabbayes@uni v -brest.fr (H. des Abbayes).

/

33-2-9801-6153; fax: ꢃ33-2-9801-

/

PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 9 9 2 - 7

´

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ

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215

Scheme 1.

allowing them to react with an aldehyde to afford an

imine able at once to recoordinate to the metal.

ment with this LM(CO)₄structure: four (ratio 1:1:1:1;

R¹"R²) or three (ratio 2:1:1; R¹ꢂR²) non equivalent

/

In order to shed light on this situation (also met in the

reductive amination catalysed by transition metal ca-

tions) we undertook the synthesis of simpler complexes

and the study of their behaviour towards aldehydes.

signals appear for the carbon monoxide ligands (Table

1). As better yields were obtained with Mo(CO)₆, mainly

the reactivity of cis-LMo(CO)₄complexes towards

aldehydes was studied.

2.2. Imino derivatives with aldehydes RCHO

2. Results and discussion

The reaction was run at 100 8C in DMF in presence

of THF, MgSO₄and a stoechiometric amount of an

2.1. Amino complexes

aldehyde (RCHO). Redꢀbrown microcrystalline solids

/

A series of cis-LM(CO)₄complexes was prepared by

R¹R²Nꢀ

were obtained and characterized first by ¹³C-NMR and

IR spectroscopy. IR spectroscopy proved to be most

helpful for the identification of the resulting complexes

(Table 2) and indicated that the Mo(CO)₄pattern was

maintained since the four characteristic n(CO) bands

were still present. In addition, the disappearance of the

nNH₂stretching bands (doublet; 3250, 3300 cm^ꢄ1), was

reaction of non symmetrical diamines (Lꢂ

/

(CH₂)_nꢀNH₂) with metal carbonyls (Scheme 3, Table

/

1). IR data (see experimental section) are consistent with

a M(CO)₄group having a local C₂v symmetry since the

four expected n(CO) IR stretching band are observed

(2A₁ꢃ

/

B₁ꢃ

B₂) [9]. ¹³C-NMR spectra are also in agree-

/

Scheme 2.

´

216

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ222

/

Scheme 3.

accompanied by a new absorption (Â

/

1665 cm^ꢄ1

double bond. Actually this

)

complex 15 (only the Z isomer crystallized) and

analyzed by X ray diffraction (Fig. 1, Tables 3 and 4)

ascribable to a ꢀ

/

CÄ

/

Nꢀ

/

was confirmed by ¹³C-NMR which in addition to the

carbonyl resonances, exhibited the characteristic sp²

clearly showing the tight bonding of the iminoꢀnitrogen

/

atom N¹, since the Moꢀ

shortened.

The Moꢀ

/

N¹bond appears significantly

carbon atom signal of an imine at 150ꢀ160 ppm.

/

When R is aryl or heteroaryl, complexes are obtained

as E,Z mixtures of stereoisomers (complexes 14 to 16

and 18). Suitable monocrystals could be grown for

/

N²distance is essentially the same as the

corresponding bond lengths in other complexes with

saturated amines [10ꢀ12]. The strong electron donor

/

Table 1

¹³C-NMR selected data and yields of complexes 6 to 11

a

No.

R1

R2

n

M

Yield

¹³C-NMR (d_CO

)

6a

6b

H

Me

Et

0

1

0

1

Cr

Mo

W

35

87

30

31

75

35

30

93

37

40

90

40

54

85

25

35

77

40

215.1; 215.9; 226.5; 227.6

207.5; 208.2; 221.2; 222.4

204.4; 205.4; 213.5; 214.1

215.8; 216.9; 226.9; 228.4

207.1; 208.0; 220.7; 221.9

204.4; 205.6; 213.4; 213.8

215.1; 216.4; 226.4; 228.0

207.1; 208.0; 220.6; 222.0

204.3; 205.5; 213.2; 213.8

214.9; 215.5; 224.7; 226.1

206.9; 207.7; 219.6; 221.0

204.4; 205.6; 211.8; 212.4

214.9 ^b; 226.2; 228.6

H

6c

7a

H

Cr

Mo

W

7b

7c

H

Et

H

8a

8b

H

n-Pr

Me

Cr

Mo

W

H

8c

9a

H

Cr

Mo

W

9b

9c

H

10a

10b

10c

11a

11b

11c

Me

Cr

Mo

W

206.9 ^b; 220.2; 223.0

205.3 ^b; 213.2; 214.4

Cr

Mo

W

214.2 ^b; 223.9; 226.5

206.5 ^b; 219.0; 221.6

205.5 ^b; 212.2; 213.0

a

In DMSO-d₆(75.47 MHz).

Double intensity.

b

Table 2

Selected data for imine complexes 14 to 19

Starting cis-Mo(CO)₄L complexes

Imine complexes

a

IR (cm^ꢄ1

)

No.

R1

R2

n

No.

R

Yield

n(CÄN)

n(CO)

6b

H

Me

0

1

14

15

16

17

18

19

2-Furyl

Phenyl

H

77

70

88

70

73

1675 (w)

1670 (w)

1675 (w)

1825 (m) 1870 (s,sh) 1885 (vs) 2000 (w)

1820 (m) 1865 (s,sh) 1880 (s) 2000 (w)

1820 (m) 1865 (s,sh) 1880 (vs) 2000 (w)

10b

11b

Me

Phenyl

H

a

In CH₂Cl₂.

´

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ

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217

Table 4

Positional parameters and estimated standard deviations for complex

15

Atom

x

y

z

B (A²)

Mo

0.36922(2)

0.1259(2)

0.3976(3)

0.3619(2)

0.2937(3)

0.2281(2)

0.4053(2)

0.5520(2)

0.2168(3)

0.3926(3)

0.3645(3)

0.3248(3)

0.5046(3)

0.5869(3)

0.3609(3)

0.2673(3)

0.2091(3)

0.1260(4)

0.1418(4)

0.6161(3)

0.5756(3)

0.17987(2)

0.1453(2)

0.70608(4)

0.7348(4)

0.8636(4)

1.0733(3)

0.6171(4)

0.4928(4)

0.4332(3)

0.6772(4)

0.7210(5)

0.8121(5)

0.9376(5)

0.6376(5)

0.3806(4)

0.5167(5)

0.3232(4)

0.3378(5)

0.2155(5)

0.2982(8)

0.4596(8)

0.8187(6)

0.6681(6)

3.526(5)

8.47(9)

7.17(8)

6.00(7)

8.59(9)

6.69(7)

3.84(6)

4.29(6)

5.27(9)

4.64(8)

4.18(7)

5.15(9)

4.79(8)

5.01(9)

4.18(8)

4.41(8)

6.1(1)

O(1)

O(2)

O(3)

O(4)

O(5)

N(1)

N(2)

C(1)

C(2)

C(3)

C(4)

C(5)

C(6)

C(7)

C(8)

C(9)

C(10)

C(11)

C(12)

C(13)

ꢄ0.0011(2)

0.2513(2)

0.3627(2)

0.0199(2)

0.1377(2)

0.2083(2)

0.1572(2)

0.0632(2)

0.2235(2)

0.2970(2)

0.1793(3)

0.1687(3)

0.0920(2)

0.0413(2)

0.0062(3)

ꢄ0.0391(3)

ꢄ0.0293(3)

0.1738(3)

0.2988(3)

Fig. 1. ORTEP drawing of the molecular structure of complex 15 (Z

isomer).

Table 3

˚

Selected bond lengths (A) and bond angles (8) for complex 15

Bond lengths

8.0(1)

8.6(1)

Moꢀ

O(1)ꢀ

O(2)ꢀ

O(3)ꢀ

/

N(1)

N(2)

C(1)

C(2)

C(3)

C(4)

2.283(2)

2.342(2)

1.942(3)

2.029(3)

1.940(3)

2.024(3)

1.154(4)

1.140(3)

1.155(3)

O(4)ꢀ

O(5)ꢀ

N(1)ꢀ

N(2)ꢀ

C(5)ꢀ

/

C(4)

C(8)

C(11)

1.135(4)

1.356(4)

1.361(5)

1.469(3)

1.268(3)

1.474(4)

1.482(4)

1.503(4)

/

6.6(1)

6.3(1)

/

C(5)

C(7)

C(6)

C(12)

C(13)

C(6)

/

Starred atoms were refined isotopically. Anisotropically refined

atoms are given in the form of the isotropic equivalent displacement

parameter defined as:

/

C(1)

C(2)

C(3)

/

(4=3)

Â [a²B(1; 1)ꢃb²B(2; 2)ꢃc²B(3; 3)

Bond angles

N(1)ꢀMoꢀ

N(2)ꢀMoꢀ

C(1)ꢀMoꢀ

/

N(2)

C(1)

C(2)

C(3)

C(4)

C(1)

C(2)

C(3)

C(4)

76.94(8)

101.3(1)

92.8(1)

169.8(1)

94.5(1)

177.9(1)

94.2(1)

92.9(1)

93.7(1)

87.1(1)

C(1)ꢀ

C(2)ꢀ

C(3)ꢀ

MoꢀC(1)ꢀ

MoꢀC(2)ꢀ

MoꢀC(3)ꢀ

MoꢀC(4)ꢀ

/

Moꢀ

/

C(3)

C(4)

C(3)

C(4)

O(1)

O(2)

O(3)

O(4)

88.7(1)

85.2(1)

89.3(1)

ꢃab(cos gB(1; 2)ꢃac(cos bB(1; 3)ꢃbc(cos aB(2; 3)]:

/

170.3(1)

84.7(1)

/

dehyde imines polymerize [16] but in some rare cases

they have been isolated in the condensed state when the

nitrogen atom bears a bulky substituent [17]. Thus,

/

177.7(3)

173.8(3)

178.7(3)

171.6(3)

/

coordination to the metal moiety stabilizes the imine

1

/

C(2)

(CH₂Ä

/

Nꢀ

/

R). The H-NMR spectra of metalꢀ

/methani-

mines, which can also be represented as formal resonat-

ing metalateꢀiminium limit species (Scheme 4) exhibit a

characteristic AB quartet centred at 7.5 ppm (see

Section 4 for NMR detailed data). The high field

/

effect of the bidentate ligand is clearly indicated by the

short molybdenumꢀcarbon (CO) bonds trans to the

nitrogen atoms (p-back bonding). The N¹ꢀ N²

Moꢀ

/

doublet (J_AB

ꢂ/14.1 Hz) is strongly enhanced by NOE

angle is acute, as observed in other tetracarbonyl

molybdenum complexes with chelating diamines or

diphosphines [10,13,14]. This kind of imine complexes

is usually prepared starting from a preformed imine

which is then reacted with the metal [15]. We also

checked this route and observed that an E imine on

reaction with hexacarbonyl metals led to a mixture of E

and Z imines, probably as a result of an unfavourable

interaction of the R group of the starting imine with the

M(CO)₄moiety.

interaction with the Nꢀ/CH₂group (triplet at 2.7 ppm).

To our knowledge, this constitutes the first example

of a methanimine stabilization by a bulky zero oxidation

state metallic center which sterically prevents from

cyclotrimerisation, as do t-butyl and bis trimethylsilyl-

methane substituents [17].

Interestingly the reaction of the ethylene diamine

complex 12 with two equivalents of formaldehyde led

to the stable bis methanimine complex 20 (Scheme 5).

2.3. Imino derivatives with formaldehyde HCHO

When R is hydrogen, stable monomeric methanimines

are obtained (complexes 17 and 19). Generally formal-

Scheme 4.

´

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A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ222

/

complex 10b of N,N-dimethylethylenediamine to give

the new bis-imine dinuclear complex 24 (Scheme 8).

The IR spectrum of this complex exhibits the four

n(CO) stretching bands for the Mo(CO)₄groups and the

new n(CÄ/N) absorption band for the two imine func-

tions. ¹³C-NMR spectrum is in agreement with a

symmetrical cis-Mo(CO)₄L complex and presents only

one set of signals: three signals (ratio 2:1:1) for the

carbonyl ligands, one peak for the two equivalent

carbon atoms of the imine functions, and three signals

for the carbon atoms a to nitrogen (methyl groups are

equivalent). The presence of only one set of peaks on the

spectrum led us to conclude to the formation of only one

isomer, among three possible, probably the E,E isomer,

sterically favoured.

By now we call back to mind that we first reported the

direct regiofunctionnalization of cyclic and linear tetra-

amine chromium complexes with alkyl halides (instead

of carbonyl compounds) as electrophiles; at that time,

we observed that in the case of linear tetraamines, only

special activated alkyl halides such as a,a?-orthodibro-

moxylene gave a selective alkylation at the pendant arm

amino function, leading to a new v-tertiary amine.

When applied to other mono alkyl halides, benzyl or

allyl bromides for instance, this methodology led to the

non selective polyalkylation of the tetramine [19].

The reason for this failure with simple alkyl halides

lies in the fact that in this case, the new secondary amine

produced by v-N alkylation competes immediately at

the metal center to liberate the hemilabile v-NH₂

function which is then polyalkylated.

Scheme 5.

Scheme 6.

We may infer that the two imines are not formed

simultaneously by complete liberation of the diamine (if

so, polymeric formol polyaminal would have been

produced) but successively.

Under slightly modified conditions (see Section 4) the

ethylenetriamine complex 13 leads to the corresponding

v,v?-bis methanimine complex 21 (Scheme 6).

Even more convincing, the reaction of the tris

cyclohexylamineꢀ Mo(CO)₃complex 22 with formalde-

/

hyde in the presence of THF gave the fac-cyclic

hexahydrotriazine Mo(CO)₃complex 23, obviously

resulting from the progressive release of the amine

from the metal, followed by the transient imine forma-

tion, cyclotrimerisation and subsequent recoordination

to the Mo(CO)₃moiety (Scheme 7). This complex is

identical to that obtained by reacting the preformed

cyclic triazine with Mo(CO)₆[18].

2.4. Imino derivatives with glyoxal (CHO)₂

An extension of the study of reactivity of primary/

tertiary diamine complexes has been obtained with a

particular aldehyde: glyoxal. Under the conditions

previously described for non heteroaromatic aldehydes,

glyoxal reacts with two equivalents of the cis-Mo(CO)₄L

Scheme 8.

Scheme 7.

´

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ

/222

219

So the replacement of alkyl halides by aldehydes or

ketones as electrophiles opened a wider field of applica-

tions, since the coordinating ability of an imine is

actually weaker than that of a primary amine, itself

weaker than that of a secondary amine; from these

observations we thus propose the following order of

binding strength for nitrogen ligands toward Group 6

metal carbonyls:

4.1. General procedure for the synthesis of complexes 6 to

11

M(CO)₆(Mꢂ

triamine (1.0 mmol) were heated at reflux (142 8C) in

di-n-butylether (20 ml)/THF (3 ml) for 2 h (MꢂCr,

Mo) or 6ꢀ7 h (MꢂW), while occasionally returning the

/

Cr, Mo, W) (1.1 mmol) and diamine or

/

sublimed M(CO)₆to the reaction solution by scraping

the condenser walls. After cooling to room temperature

(r.t.), the solvent was removed under reduced pressure

and the residue was washed several times with hexane at

RꢀCHÄNꢀBRNH₂BR₂NH

ꢄ10 8C. The resulting yellow powder was then dried in

/

vacuum at 50 8C.

4.1.1. cis-[{MeNH(CH₂)₂NH₂}Cr(CO)₄] (6a)

Yield: 35%. ¹³C-NMR (DMSO-d₆): d 42.7 (Ca-N);

44.1 (Me); 54.3 (Ca-N); 215.1, 215.9, 226.5, 227.6 (CO).

IR (CH₂Cl₂): cm^ꢄ11815 (m), 1855 (s, sh), 1865 (vs),

2000 (w) n(CO).

3. Conclusion

The isolation of stable formaldehyde imine of both

fac-LM(CO)₃and cis-LM(CO)₄complexes starting

from the parent amino complexes strongly suggests the

hemilability of the primary amino function bound to the

metal. The facile opening of such chelating unsymme-

trical diamines appears thus to begin with the previously

observed regioselective v,v?-dialkylation of linear tetra-

amines, while secondary metal bound amines cannot be

displaced.

4.1.2. cis-[{MeNH(CH₂)₂NH₂}Mo(CO)₄] (6b)

Yield: 87%. ¹³C-NMR (DMSO-d₆): d 43.4 (Ca-N);

44.5 (Me); 54.6 (Ca-N); 207.5, 208.2, 221.2, 222.4 (CO).

IR (CH₂Cl₂): cm^ꢄ11825 (m), 1865 (s, sh), 1885 (vs),

2005 (w) n(CO).

Noteworthy is the stabilizing effect of the M(CO)₃

and M(CO)₄moieties on methanimines which has the

same effect as the bulky bis trimethylsilyl methane group

for instance [17b]. Moreover, the metal bound imine

although stabilized by the metal fragment is still reactive

and is easily reduced by NaBH₄for instance. So

methanimines lead to the corresponding N-monomethy-

lamine quantitatively.

4.1.3. cis-[{MeNH(CH₂)₂NH₂}W(CO)₄] (6c)

Yield: 30%. ¹³C-NMR (DMSO-d₆): d 44.2 (Ca-N);

45.4 (Me); 55.1 (Ca-N); 204.4, 205.4, 213.5, 214.1 (CO).

IR (CH₂Cl₂): cm^ꢄ11815 (m), 1855 (s, sh), 1865 (vs),

2000 (w) n(CO).

4.1.4. cis-[{EtNH(CH₂)₂NH₂}Cr(CO)₄] (7a)

Yield: 31%. ¹³C-NMR (DMSO-d₆): d 14.4 (Me); 42.7,

51.0, 51.5 (Ca-N); 215.8, 216.9, 226.9, 228.4 (CO). IR

(CH₂Cl₂): cm^ꢄ11815 (m), 1855 (s, sh), 1865 (vs), 2000

(w) n(CO).

The reactivity of these new metal stabilized imines is

now under investigation.

4.1.5. cis-[{EtNH(CH₂)₂NH₂}Mo(CO)₄] (7b)

Yield: 75%. ¹³C-NMR (DMSO-d₆): d 14.2 (Me); 42.7,

51.2, 51.7 (Ca-N); 207.1, 208.0, 220.7, 221.9 (CO). IR

(CH₂Cl₂): cm^ꢄ11820 (m), 1860 (s, sh), 1870 (vs), 2005

(w) n(CO).

4. Experimental

All reactions were carried out under nitrogen atmo-

sphere using the Schlenk technique, and all solvents

were freshly distilled under an inert atmosphere on

appropriate dryers. All reagents were purchased from

commercial suppliers and used without further purifica-

4.1.6. cis-[{EtNH(CH₂)₂NH₂}W(CO)₄] (7c)

Yield: 35%. ¹³C-NMR (DMSO-d₆): d 14.5 (Me); 43.8,

52.5 (2C) (Ca-N); 204.4, 205.6, 213.4, 213.8 (CO). IR

(CH₂Cl₂): cm^ꢄ11815 (m), 1855 (s, sh), 1865 (vs), 2000

(w) n(CO). Anal. Calc.: C, 25.04; H, 3.13; N, 7.30.

Found: C, 25.12; H, 3.31; N, 7.33%.

tions. Infrared spectra were obtained using a Perkinꢀ

/

Elmer 1430 spectrophotometer. NMR spectra were

1

recorded on either Bruker AC 300 (FT 300 MHz, H;

75.47 MHz, ¹³C) or Bruker Advance PRX 400 (FT 400

MHz, ¹H 100 MHz, ¹³C) spectrometers. Chemical shifts

1

for H and ¹³C spectra were referenced using internal

4.1.7. cis-[{n-PrNH(CH₂)₂NH₂}Cr(CO)₄] (8a)

Yield: 30%. ¹³C-NMR (DMSO-d₆): d 11.5 (Me); 21.5

(Cb-N); 42.3, 51.0, 59.0 (Ca-N); 215.1, 216.4, 226.4,

228.0 (CO). IR (CH₂Cl₂): cm^ꢄ11820 (m), 1860 (s, sh),

1870 (vs), 2005 (w) n(CO).

solvent resonance and are reported relative to TMS.

Elemental analyses were performed by the Service

National de Microanalyses du CNRS, at Vernaison,

France.

´

220

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ

/222

4.1.8. cis-[{n-PrNH(CH₂)₂NH₂}Mo(CO)₄] (8b)

Yield: 93%. ¹³C-NMR (DMSO-d₆): d 11.5 (Me); 21.8

(Cb-N); 42.6, 52.1, 58.9 (Ca-N); 207.1, 208.0, 220.6,

222.0 (CO). IR (CH₂Cl₂): cm^ꢄ11825 (m), 1865 (s, sh),

1885 (vs), 2010 (w) n(CO).

4.1.17. cis-[{Me₂N(CH₂)₃NH₂}Mo(CO)₄] (11b)

Yield: 77%. ¹³C-NMR (DMSO-d₆): d 25.4 (Cb-N);

46.1 (Ca-N); 59.3 (2Me); 66.5 (Ca-N); 206.5 (2C), 219.0,

221.6 (CO). IR (CH₂Cl₂): cm^ꢄ11820 (m), 1865 (s, sh),

1880 (vs), 2005 (w) n(CO). Anal. Calc.: C, 34.84; H,

4.52; N, 9.03. Found: C, 35.11; H, 4.56; N, 9.32%.

4.1.9. cis-[{n-PrNH(CH₂)₂NH₂}W(CO)₄] (8c)

Yield: 37%. ¹³C-NMR (DMSO-d₆): d 11.4 (Me); 22.0

(Cb-N); 43.6, 52.8, 60.1 (Ca-N); 204.3, 205.5, 213.2,

213.8 (CO). IR (CH₂Cl₂): cm^ꢄ11825 (m), 1860 (s, sh),

1870 (vs), 2005 (w) n(CO).

4.1.18. cis-[{Me₂N(CH₂)₃NH₂}W(CO)₄] (11c)

Yield: 40%. ¹³C-NMR (DMSO-d₆): d 25.4 (Cb-N);

46.8 (Cb-N); 57.3 (2Me); 67.0 (Ca-N); 205.5 (2C), 212.2,

213.0 (CO). IR (CH₂Cl₂): cm^ꢄ11810 (m), 1855 (s, sh),

1865 (vs), 2000 (w) n(CO).

4.1.10. cis-[{MeNH(CH₂)₃NH₂}Cr(CO)₄] (9a)

Yield: 40%. ¹³C-NMR (DMSO-d₆): d 27.2 (Cb-N);

46.1 (Ca-N); 46.8 (Me); 57.6 (Ca-N); 214.9, 215.6, 224.7,

226.1 (CO). IR (CH₂Cl₂): cm^ꢄ11810 (m), 1855 (s, sh),

1865 (vs), 2000 (w) n(CO).

4.1.19. cis-[{H₂N(CH₂)₂NH₂}Mo(CO)₄] (12)

¹³C-NMR (DMSO-d₆): 40.7(Ca-N); 227.4, 229.2

(CO). IR (nujol): cm^ꢄ12005 (s), 1885 (vs), 1865 (vs),

1825 (m) n(CO).

4.1.11. cis-[{MeNH(CH₂)₃NH₂}Mo(CO)₄] (9b)

Yield: 90%. ¹³C-NMR (DMSO-d₆): d 27.3 (Cb-N);

46.0 (Ca-N); 46.2 (Me); 57.4 (Ca-N); 206.9, 207.7, 219.6,

221.0 (CO). IR (CH₂Cl₂): cm^ꢄ11815 (m), 1860 (s, sh),

1875 (vs), 2005 (w) n(CO).

4.1.20. fac-[{H₂N(CH₂)₂NH(CH₂)₂NH₂}Mo(CO)₃]

(13)

¹³C-NMR (DMSO-d₆): 40.4 (Ca-NH₂); 49.0 (Ca-

NH); 227.7 (2CO); 229.9 (CO). IR (CH₂Cl₂): cm^ꢄ1

1885 (s), 1770 (vs) n(CO).

4.1.12. cis-[{MeNH(CH₂)₃NH₂}W(CO)₄] (9c)

Yield: 40%. ¹³C-NMR (DMSO-d₆): d 27.1 (Cb-N);

46.5 (Ca-N); 47.4 (Me); 57.7 (Ca-N); 204.4, 205.6, 211.8,

212.4 (CO). IR (CH₂Cl₂): cm^ꢄ11810 (m), 1855 (s, sh),

1865 (vs), 2000 (w) n(CO).

4.2. General procedure for the synthesis of imines 14 to

21

To a solution of cis-Mo(CO)₄L complex (1.0 mmol)

in DMF (10 ml) in presence of THF (3 ml) and an excess

of dry MgSO₄, was added a stoechiometric amount of

an aldehyde (1.0 mmol) (if the aldehyde is heteroaro-

matic, the addition of the co-solvent (THF) is not

4.1.13. cis-[{Me₂N(CH₂)₂NH₂}Cr(CO)₄] (10a)

Yield: 54%. ¹³C-NMR (DMSO-d₆): d 41.1 (Ca-N);

55.4 (2Me); 62.7 (Ca-N); 214.9 (2C), 226.2, 228.6 (CO).

IR (CH₂Cl₂): cm^ꢄ11815 (m), 1855 (s, sh), 1865 (vs),

2000 (w) n(CO). Anal. Calc.: C, 38.09; H, 4.77; N, 11.11.

Found: C, 37.91; H, 4.83; N, 11.26%.

necessary). After 3ꢀ4 h of stirring at 100 8C, the

/

mixture was cooled to r.t. and the solvent was removed

under reduced pressure. The residue adsorbed on

MgSO₄was extensively extracted with dichloromethane;

after evaporation of the solvent, a redꢀbrown micro-

/

crystalline solid was obtained. IR data are given in

Table 2.

4.1.14. cis-[{Me₂N(CH₂)₂NH₂}Mo(CO)₄] (10b)

Yield: 85%. ¹³C-NMR (DMSO-d₆): d 41.5 (Ca-N);

55.1 (2Me); 63.0 (Ca-N); 206.9 (2C), 220.2, 223.0 (CO).

IR (CH₂Cl₂): cm^ꢄ11820 (m), 1860 (s, sh), 1875 (vs),

2005 (w) n(CO). Anal. Calc.: C, 32.43; H, 4.10; N, 9.46.

Found: C, 32.70; H, 4.12; N, 9.76%.

4.2.1. Complex 14 (mixture of E and Z isomers)

Yield: 77%. ¹³C-NMR (DMSO-d₆) isomer E (maj.): d

43.6 (CH₃); 54.0, 55.4 (Ca-N); 110.7, 120.5, 144.7, 149.4

(C₄H₃O); 158.5 (CÄ

isomer Z (min.): d 44.6 (CH₃), 54.1, 65.8 (Ca-N); 108.9,

122.6, 144.6, 149.7 (C₄H₃O); 163.2 (CÄN); 206.4, 208.0,

221.2, 222.4 (CO).

/

N); 206.8, 207.9, 221.1, 222.3 (CO);

4.1.15. cis-[{Me₂N(CH₂)₂NH₂}W(CO)₄] (10c)

Yield: 25%. ¹³C-NMR (d_6ꢀDMSO): d 42.6 (Ca-N);

56.5 (2Me); 63.9 (Ca-N); 205.3 (2C), 213.2, 214.4 (CO).

IR (CH₂Cl₂): cm^ꢄ11810 (m), 1845 (s, sh), 1855 (vs),

2000 (w) n(CO).

/

4.2.2. Complex 15 (mixture of E and Z isomers)

Yield: 70%. ¹³C-NMR (CD₂Cl₂) of isomer E (maj.): d

54.2 (Ca-N); 55.0 (Me); 64.3 (Ca-N); 113.1, 120.7, 147.0,

4.1.16. cis-[{Me₂N(CH₂)₃NH₂}Cr(CO)₄] (11a)

Yield: 35%. ¹³C-NMR (DMSO-d₆): d 24.9 (Cb-N);

45.7 (Ca-N); 56.2 (2Me); 66.2 (Ca-N); 214.2 (2C), 223.9,

226.5 (CO). IR (CH₂Cl₂): cm^ꢄ11810 (m), 1855 (s, sh),

1865 (vs), 2000 (w) n(CO).

148.7 (C₄H₃O); 152.9 (CÄ

(CO); isomer Z (min.): d 56.2 (Ca-N); 63.0 (Me); 64.6

(Ca-N); 112.9, 120.5, 147.0, 148.9 (C₄H₃O); 157.3 (CÄ

N); 207.2 (2C), 222.9, 223.3 (CO).

/N); 206.7 (2CO), 222.1, 222.4

/

´

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ

/222

221

4.2.3. Crystallographic study of complex 15

Suitable crystals for single-crystal X-ray diffraction

plet, 2H, Jꢂ

(t, 2H, Jꢂ5.6 Hz, CH₂a-N); 3.83 (t, 2H, Jꢂ

CH₂a-N); 7.51 (d, 1H, Jꢂ14.1 Hz, H imine); 7.60 (d,

1H, Jꢂ14.1 Hz, H imine).

/

5.6 Hz, CH₂b-N); 2.67 (s, 6H, 2Me); 2.78

/

5.6 Hz,

studies were obtained from a 1:1 hexaneꢀ/diethylether

/

mixture at r.t. The crystal data and the structure

refinement are collected in Tables 3 and 4. The sample

/

(0.30ꢅ

diffractometer ^{CAD4 NONIUS}with graphite monochro-

matized MoꢀK_aradiation [22]. The cell parameters are

obtained by fitting a set of 25 high-theta reflections. The

data collection (2u_max548, scan v/2uꢂ1, t_max60 s,

range hkl: h ꢄ14,14 k 0,18 l 0,9) gives 2954 unique

reflections from which 2208 with I ꢀ2.0s(I). After

/

0.20ꢅ

/

0.20 mm³) is studied on an automatic

4.3. Complexes 20 and 21

/

These were prepared according to the general proce-

dure described for imine complexes 14 to 19 but from

two equivalents of formaldehyde, in THF at 50 8C.

ꢂ

/

ꢂ

/

4.3.1. Complex 20

13

Lorenz and polarization corrections [26] and also

absorption corrections (psi scans) the structure was

solved with ^SIR-97 [20] which reveals the non-hydrogen

atoms of the compound. After anisotropic refinement a

Fourier difference reveals many hydrogen atoms. The

whole structure was refined with ^SHELXL-97 [24] by the

full-matrix least-square techniques (use of F²magnitude;

x, y, z, b_ijfor Mo, C, O and N atoms, x, y, z in riding

mode for H atoms; 191 variables and 2742 observations;

Yield: 60%.

162.1 (CÄ

(CD₂Cl₂): d 3.72 (s, 4H, CH₂a-N); 7.59 (d, 2H, Jꢂ

Hz, NÄCH_trans); 7.71 (d, 2H, Jꢂ14.1 Hz, NÄCH_cis). IR

(CH₂Cl₂): cm^ꢄ11820 (m), 1865 (s, vs), 1885 (vs), 2000

(w) n(CO); 1670 n(CÄN).

C-NMR (CD₂Cl₂): d 64.1 (CH₂a-N);

1

/

N); 207.4 (2CO), 222.3 (2C) (CO). H-NMR

/14.1

/

4.3.2. Complex 21

The reaction was run in THF at a temperature kept

below 60 8C.

calc wꢂ

/

1/[s²(F²_o)ꢃ

/

(0.035P)²ꢃ

/

0.61P] where Pꢂ

/

(F²_oꢃ

/

2F²_c)/3 with the resulting Rꢂ

/

0.023, R_wꢂ0.058 and

/

Yield: 60%. ¹³C-NMR (CD₂Cl₂): d 49.8 (2C) (CH₂a-

˚

S_wꢂ

/

1.011 (residual Dr 5

/

0.46 e A^ꢄ3).

NH); 61.3 (2C) (CH₂a-NÄ

/

CH₂); 162.5 (2C) (CÄ

/

N);

Atomic scattering factors from International Tables

for X-ray Crystallography [21]. ^ORTEPviews realized

with ^PLATON-98 [25] and ORTEP-3 [23].

229.3 (CO), 229.7 (2CO). ¹H-NMR (DMSO-d₆):

2.61(m); 2.96(m); 3.40ꢀ3.65(m) (CH₂a-N); 7.51 (dt,

H_transimine, Jꢂ14.6 Hz); 7.57 (dt, H_cisimine, Jꢂ

14.6 Hz). IR (CH₂Cl₂): 1770 (vs), 1882 (s) n(CO); 1670

n(CÄN).

/

4.2.4. Complex 16 (mixture of E and Z isomers)

Yield: 70%. ¹³C-NMR (CD₂Cl₂) of isomer E (maj.): d

55.8 (Ca-N); 56.0 (2Me); 64.2 (Ca-N); 128.7, 129.4,

/

4.4. Complex 22

131.4, 135.2 (C₆H₅); 171.7 (CÄ

222.7 (CO); isomer Z (min.): d 55.4 (2Me); 63.4 (2 Ca-

N),

/N), 207.0 (2CO); 221.2,

This was prepared according to the procedure de-

scribed for complexes 6 to 11 but from three equivalents

of cyclohexylamine.

Yield: 47%. ¹³C-NMR (DMSO-d₆): d 24.7 (Cg); 25.4

(Cd) ; 35.22 (Cb); 50.0 (Ca).

N); 129.2, 129.8, 131.5, 132.5 (C₆H₅); 168.2 (CÄ

/

206.5 (2C); 220.5, 222.1 (CO).

4.2.5. Complex 17

Yield: 88%. ¹³C-NMR (CD₂Cl₂): d 55.5 (2Me); 60.9,

63.6 (Ca-N); 161.8 (CÄ

/

N); 206.8 (2C), 221.8, 222.4

(CO). H-NMR (CD₂Cl₂): d 2.70 (t, 2H, Jꢂ5.6 Hz,

CH₂a-N); 2.80 (s, 6H, 2Me); 3.76 (t, 2H, Jꢂ5.6 Hz,

CH₂a-N); 7.52 (d, 1H, Jꢂ14.1 Hz, H imine); 7.67 (d,

1H, Jꢂ14.1 Hz, H imine).

4.5. Complex 23

1

/

This was prepared according to the procedure de-

/

scribed for complexes 20 and 21.

13

/

Yield: 34%.

62.0 (C₆H₁₁); 75.2 (NCH₂N); 231.6 (3CO). IR (CH₂Cl₂):

C-NMR (CDCl₃): d 25.0, 24.2, 28.6,

4.2.6. Complex 18 (mixture of E and Z isomers)

Yield: 70%. ¹³C-NMR (CD₂Cl₂) of isomer E (maj.): d

28.9 (Cb-N); 56.3 (2Me); 56.6, 66.3 (Ca-N); 128.8, 128.9,

cm^ꢄ11770 (vs), 1905 (s).

4.6. Complex 24

129.2, 132.5 (C₆H₅); 171.0 (CÄ

/N); 206.4 (2CO), 221.0,

221.6 (CO); isomer Z (min.): d 31.3 (Cb-N); 55.7 (2Me);

66.6, 69.0 (Ca-N); 128.5, 128.6, 131.0, 136.5 (C₆H₅);

This was prepared according to the procedure de-

scribed for complexes 14 to 19 but from 0.5 equivalent

of glyoxal.

173.1 (CÄ

/

N); 206.2 (2CO), 221.0, 221.6 (CO).

13

Yield: 68%.

C-NMR (CD₂Cl₂): d 42.5 (CH₂a-N);

N); 206.5 (2CO),

220.4, 222.4 (CO). H-NMR (CD₂Cl₂): d 2.48 (t, 4H,

Jꢂ5.6 Hz, CH₂a-N); 2.76 (s, 12H, CH₃); 3.00 (t, 4H,

Jꢂ5.6 Hz, CH₂a-N); 7.94 (s, 2H, CHÄN). IR (CH₂Cl₂):

4.2.7. Complex 19

Yield: 73%. ¹³C-NMR (CD₂Cl₂): d 27.9 (Cb-N); 56.3

55.8 (CH₃); 63.5 (CH₂a-N); 162.6 (CÄ

/

1

(2Me); 66.6, 68.3 (Ca-N); 163.3 (CÄ

/

N); 206.2 (2CO),

1

220.6, 221.6 (CO). H-NMR (CD₂Cl₂): d 1.88 (quintu-

/

´

222

A.-C. Herve et al. / Journal of Organometallic Chemistry 664 (2002) 214ꢀ222

/

cm^ꢄ11820 (m), 1860 (s, vs), 1875 (vs), 2000 (w) n(CO);

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(c) F.A. Cotton, Inorg. Chem. 3 (1964) 702;

1670 n(CÄ

/

N).

(d) R.B. King, A. Fronzaglia, Inorg. Chem. 5 (1966) 1837;

(e) P.S. Braterman, Metal Carbonyl Spectra, Academic Press,

London, 1975.

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Article Doi

Hemilability of the primary amine-metal bond in polyamine-(group 6) metal carbonyl complexes

DOI: 10.1016/S0022-328X(02)01992-7

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