Synthesis, characterization, inequivalency of methylene proton and proton lability in the amino ligand of trans-[dichloro{(N-ferrocenyl methyl)amine}(η2-ethene)platinum] complexes

Article abstract of DOI:10.1016/S1386-1425(02)00334-7

Synthesis, characterization, inequivalency of methylene proton and proton lability in the amino ligand of trans-[dichloro{(N-ferrocenyl methyl)amine}(η²-ethene)platinum] complexes were investigated. Elemental analysis, infrared spectroscopy and

Full text of DOI:10.1016/S1386-1425(02)00334-7

Spectrochimica Acta Part A 59 (2003) 1265ꢂ1275
/
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Synthesis, characterization, inequivalency of methylene proton
and proton lability in the amino ligand of trans-[dichloro{(N-
ferrocenyl methyl)amine}(h2-ethene)platinum] complexes
Ibrahim M. Al-Najjar a,*, Abdullah M. Abdulrahman a, Jamal K. Al-Refai a,
Latifah A. Al-Shabanah b, Laila A. Al-Mutabagani b
a Petroleum and Petrochemicals Research Institute, King Abdulaziz City for Science and Technology, P.O. Box 6086, Riyadh 11442,
Saudi Arabia
b Chemistry Department, Girls College of Education, General Presidency for Girls, Riyadh, Saudi Arabia
Received 25 April 2002; received in revised form 23 August 2002; accepted 30 August 2002
Abstract
A
series of complexes of the type trans-[PtCl2(h2-ethene)(N-ferrocenyl methyl)amine)] complexes, N-
ferrocenylmethylamineꢀ H4CH2NHR], Rꢀ
[(h5-C5ÃH5)Fe(h5-C5Ã (Me, Pri , Bus, But, CH2Ph, (p-OCH3)Ph, (o-
(OCH3)Ph, (p-CH3)Ph, (o-CH3)Ph, (m-CH3)Ph, (p-Cl)Ph) have been synthesized and characterized on the basis of
elemental analysis, IR, 1H and 13C NMR spectroscopic methods. The CpCH2NHR (Cpꢀ(h5-C5H5)Fe(h5-C5H4),
region of the 1H NMR spectrum of the complexes has been investigated and shown to contain inequivalent methylene
CH coupling take place.
/
/
/
/
/
protons, NH Ã
/
CH and 195Pt Ã
/
NÃ
/
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Synthesis; Inequivalency; Methylene protons; Lability; N-Ferrocenylmethylamine; Platinum; Complexes
1. Introduction
[(h5-C5H5)Fe(h5-C5H4CHO)] as a facile method
of substituting a ferrocene group onto an organic
residue, and have studied the resultant Schiff bases
Ferrocene-containing molecules are continuing
to attract great interest as components in homo-
geneous catalysts [1], molecular sensors [2], and
molecular magnetic [3] and non-linear optical [4]
materials. Several groups have exploited Schiff
base condensation of ferrocenecarboxaldehyde
[(h5-C5H5)Fe(h5-C5H4CRÄ
/
NR?)], RꢀH, Me or
/
Ph, R?-alkyl or aryl for their non-linear optical,
and ligating [5] properties. Recently, we reported
the synthesis and characterization of new Schiff
bases of (N-ferrocenylmethylidene)imines and
their platinum(II) complexes [6]. In order to
increase the stability in solution to use these
compounds as ligands, the imino group was
reduced by NaBH4 to give the amino derivatives,
(N-ferrocenylmethyl)amine, CpCH2NHR.
* Corresponding author. Tel.: ꢁ
1-4813755.
E-mail address: alnajjar@kacst.edu.sa (I.M. Al-Najjar).
/
966-1-4813778; fax: ꢁ966-
/
1386-1425/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 1 3 8 6 - 1 4 2 5 ( 0 2 ) 0 0 3 3 4 - 7

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Reaction of these amino ligands with Zeise salt,
K[PtCl3(h2-ethene)], yield new complexes of the
type
trans-[PtCl2(h2-ethene){(h5-C5H5)Fe(h5-
C5H4CH2NHÃR)}(Rꢀaliphatic or aromatic
group).
ligand [(h5-C5H5)Fe(h5-C5H4CH2NHR)] (R-alkyl
or aryl) and their platinumꢂmetal olefin com-
plexes (Scheme 1). Furthermore the lability of the
NÃH bond, NH Ã NÃCH cou-
CH and 195Pt Ã
pling, in trans-olefin-amine complexes (i.e. A), is
also investigated and compared with that of
platinum amine link.
/
/
/
/
/
/
/
This paper describes the isolation and charac-
terization of new (N-ferrocenylmethyl)amines
Scheme 1. Schematic view of the synthesis of amine and complex formation

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1267
2. Results and discussion
Interestingly, the methylene protons in
1
CpCH2NHR, resonate in H NMR spectrum (in
1
Since relatively little was known concerning H
and 13C NMR characteristic of a system such as
CDCl3) in range, dꢀ
peak (Table 2), when Rꢀ
1ꢂ5). The resonance of CpCH2N protons is
/
3.50ꢂ/3.81 ppm as a single
/aliphatic (compounds
(A), where Xꢀ
/
chloride, olefinꢀethene, we have
/
/
prepared and studied a series of these derivatives
with different alkyl- and aryl-amine groups
(Scheme 1).
sensitive to the nature of aliphatic alkyl group
(R), which is attached to the secondary nitrogen
(Table 2). The NH proton appear as broad peak
when Rꢀ
aromatic. No significant change in CH2 resonance
when Rꢀsubstituted aromatic group (compounds
6ꢂ11, Table 2), CH2 resonate at d 3.92 ppm.
/
alkyl group and sharper when Rꢀ
/
2.1. 1H and 13C NMR chemical shifts for (N-
ferrocenylmethyl)amines
/
/
The 1H resonances of the h5-C5H5 and h5-C5H4
rings showed three resonances for the ferrocenyl
protons (one single for the unsubstituted ring,
C5H5 and two for the substituted ring C5H4 in a
5:2:2 ratio) (Table 1).
2.1.1. [(h5-C5H5)Fe(h5-C5H4CH2NHR)]
Amines were obtained by the reduction of the
appropriate imine (see Section 3), and the elemen-
1
tal analysis, m.p., H and 13C chemical shifts are
listed in Tables 1 and 2.
Table 1
Characterization data of the ligands and their complexes
No.
Ligand/(complex)
M.p. (8C)
% Analysis found/(Calc.)
C
H
N
1
C
C
C
C
C
C
C
C
C
C
C
12H15FeN/(C18H19Cl2FeNPt)
18H19FeN/(C20H23Cl2FeNPt)
15H21FeN/(C17H25Cl2FeNPt)
14H19FeN/(C16H23Cl2FeNPt)
15H21FeN/(C17H25Cl2FeNPt)
18H19FeNO/(C20H23Cl2FeNOPt)
18H19FeNO/(C20H23Cl2FeNOPt)
18H19FeN/(C20H23Cl2FeNPt)
18H19FeN/(C20H23Cl2FeNPt)
18H19FeN/(C20H23Cl2FeNPt)
17H16ClFeN/(C19H20Cl2FeNPt)
40ꢂ
/
45a
63.11/(62.92)
31.19/(32.14)
6.2/(6.59)
3.52/(3.66)
6.11/(6.11)
2.68/(2.31)
150a
2
68
162a
70.84/(70.82)
40.11/(40.09)
6.21/(6.27)
4.21/(3.89)
4.49/(4.59)
2.52/(2.34)
3
55ꢂ
/
60a
130a
66.43/(66.44)
36.16/(36.1)
7.79/(7.75)
4.27/(4.45)
5.17/(5.13)
2.57/(2.48)
125ꢂ
/
4
35
145
65.13/(65.39)
33.92/(34.87)
7.45/(7.44)
4.12/(4.20)
5.33/(5.45)
2.35/(2.54)
5
42
140a
66.41/(66.44)
35.82/(36.13)
7.62/(7.80)
4.52/(4.45)
5.20/(5.17)
2.27/(2.48)
6
67
142
67.49/(67.31)
38.51/(39.05)
6.23/(5.96)
3.86/(3.76)
4.26/(4.36)
2.10/(2.28)
7
66
110
67.43/(67.31)
39.63/(39.05)
6.22/(5.96)
4.10/(3.76)
4.36/(4.17)
2.23/(2.28)
8
55
130
70.41/(70.84)
39.50/(40.09)
6.32/(6.27)
4.49/(3.87)
4.44/(4.59)
2.10/(2.34)
9
60
100
70.82/(70.84)
40.12/(40.09)
6.27/(6.27)
3.78/(3.87)
4.59/(4.59)
2.34/(2.34)
10
11
a
60
110a
70.80/(70.84)
39.90/(40.09)
6.19/(6.27)
3.92/(3.87)
4.58/(4.59)
2.14/(2.34)
66
140
62.86/(62.71)
35.86/(36.83)
5.50/(4.95)
30.04/(3.25)
4.18/(4.30)
2.06/(2.26)
Decompose.

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Table 2
1H and 13C NMR spectra of N-ferrocenylmethyl amines CpCH2NHR

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The 13C chemical shifts for the amines are given
in Table 2. The quaternary carbon atoms are
readily identified, since they are less intense and
almost invariant in position and confirmed by
using the NOE technique. The 13C chemical shifts
[7ꢂ
/
11], if one assumes that 1J(195Ptꢂ13
/
C) is
C bond
proportional to the s character in the PtÃ
[12], and that the trans-influence of a group trans
to the olefin is reflected qualitatively by changes in
/
the strength of the s component of the PtÃ
/C bond
of the methylene carbon atoms CpCH2Ã
/
NHÃ
/
R,
[13].
Substituted amine, imines [14] and diamines
[15], are good s donor ligands. The s-donation
are readily identified, and resonate at 42.0ꢂ
/
58.0
ppm. It is worth noting that the resonance of the
CH2 carbon in amines is sensitive to the nature of
R group attached to the secondary nitrogen atom
(Table 2). This difference may be due to increasing
electron density on CH2 group as a result of s-
donation of R group.
ability of amines lies in the order Rꢀ
/
But(quaternary)ꢀ
Bui(secondary)ꢀ
Meꢀ
data, d(13CH2Ä) and 1J(195Ptꢂ13
C) has a value of 156 Hz for amine
complex 1 (RꢀMe), suggesting that amine (1)
(Table 2) may be more strongly bound than other
amines; secondly, d(13CH2Ä
) 74.4 ppm, the high-
est value obtained, Table 3 shows that the
platinumÃcarbon (olefin) bond is less strong due
to the trans effect of amine (1; RꢀMe). When
amine (3; Rꢀ
But) (Table 3) donates more elec-
/
Pri(tertiary)ꢀ
Ph [14]. Carbon-13 NMR
C) demonstrate
/
/
/
/
/
1
that J(PtÃ
/
/
2.2. 1H and 13C chemical shifts for complexes
/
2.2.1. trans-[PtCl2(h2-ethene){(h5-C5H5)Fe(h5-
C5H4CH2NHR)}]
/
Upon co-ordination the olefinic H and C atoms
exhibit large upfield chemical shifts with respect to
olefin and exhibit platinum-195 satellites with
sizeable coupling constants. The 1H and 13C
resonance patterns of the complexes in chloro-
form-d solution at ambient temperature are con-
sistent with four-co-ordination, as in the solid.
Support for the existence of four-co-ordinate
/
/
trons to the platinum (compared with amine (1)),
this causes blooming of the b2 orbital toward the
olefin which enhances the p-back bonding, result-
ing in a stabilization of the platinum olefin bond
[11,14,16]. The values d(13CH2Ä
/) 72.95 ppm and
1J(195Ptꢂ13
/
C) 186.0 Hz for complex 3, (Rꢀ
/
But),
support the above observation. Further evidence
species is provided by J(PtÃ
/
H) 58ꢂ
/
74 Hz for the
4.65
h2-ethene protons and d values of 4.13ꢂ
/
comes from the resonance of the olefinic proton,
expected for four-co-ordinate species. The 1H
and 13C resonances of ethene in four-co-ordinated
compounds e.g. trans-[PtCl2(h2-C2H4)(amine) [7],
d(CH2Ä
in Table 3.
Interestingly, the d(13CH2Ä
the other amine, where Rꢀ
Pri, Bus, or CH2Ph or
Rꢀaromatic, are in between the above two values
obtained from Rꢀ
Me and But (Table 3) which
supports the above observation. Thus as Panunzi
and co-workers [17] have suggested, in order to
obtain stable complexes as moderate bulk must be
present at the nitrogen atoms. However, such
stabilization could equally be the result of a
combination of steric and electronic effects (com-
/) 4.40, the lowest value obtained as shown
/
) values obtained for
are similar to the new complexes, d(CH2Ä
4.5ꢂ5.0 flanked by platinum-195 satellites (33%) of
59ꢂ63 Hz, in agreement with the data in Table 3.
Previous 13C NMR studies [8ꢂ
11] for related
molecules have shown that d(13C2H4) and
1J(195Ptꢂ13
C) values for ethene complexes such
/), at
/
/
/
/
/
/
/
as (A) vary from approximately 68 to 77 ppm and
156 to 180 Hz, respectively, with smaller d values
1
and larger J(195Ptꢂ13
/
C) values corresponding to
ligands such as Rꢀ
But and Me. The 13C
NRꢀ
/
/
NMR signals (main band plus 195Pt satellites) of
our new complexes fall between 72.4 and 74.4 ppm
with J(195Ptꢂ13
paring the two amine complexes with Rꢀ
But).
Moreover, 1H and 13C NMR spectra of the
olefin, when Rꢀaromatic are consistent with
/Me and
1
/
C) values of approximately 156ꢂ
/
/
186 Hz.
the above observation and the values observed
reflect the effect of substituent on the benzene ring
(Table 3).
There seems to be only small differences be-
tween our new amine derived from ferrocenecar-
boxaldehyde and amine or imine complexes

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Table 3
1H and 13C NMR spectra of trans-[PtCl2(h2-C2H4)(h5-C5H5)Fe(h5-C5H4CH2NHR(R?)] complexes
Thus the (N-ferrocenylmethyl)amines in the new
complexes are good s-donor ligands compared
with amine ligands.
It is worth noting that the presence of inequi-
valence of the proton resonances of ethene in some
of the new complexes (Table 3). In addition to the

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Fig. 1. 1H NMR spectrum of trans-[PtCl2(h2-C2H4)(h5-C5H4)Fe(h5-C5H4CH2NHCH3)] in: (a) CDCl3 solution; (b) ꢁ
D2O.
/
chemical shifts of the substituted C5H4 ring of the
ferrocenyl moiety are clearly influenced by the
of the amine 18a18b or in this context, by
complexing with metal ion. Thus although N-
nature of the NÃ
/
R substituents.
methylaniline
and
N-methylcyclohexylamine
CH coupling, the
phenomenon can be seen in the corresponding
The 1H and 13C resonances of the C5H4 ring are
shifted downfield in particular H2 and H5 as the
basicity of the N-donor atom increases.
themselves exhibit no NH Ã
/
trans-[PtCl2(h2-C2H4)(am)] complexes where
In contrast, the Cipso resonance of the coordi-
nated substituted, C5H4 ring are shifted to higher
amꢀ
NH2Me [19].
In trans-[PtCl2(h2-C2H4)(am)], the PtÃ
is always labile [20ꢂ24] (on an NMR time scale) if
/
amine including amꢀNHMe2, NHEt2, and
/
field (e.g. Cipso, dꢀ
/
80 ppm, Table 3) compared
with Cipso 87 ppm of the free amine (Table 2),
/N bond
ꢀ
/
/
and show four signals for C2, C3, C4 and C5,
indicating non-equivalency (Table 3), except, com-
pounds 6 and 7 when methoxy group are sub-
stituted in para and ortho position of benzene ring.
The 13C NMR of unsubstituted ring C5H5 show
one signal.
free amine is present, unless the amine is very
hindered sterically [24]. These observations raise
the problem of the ease of breaking the NÃ
/
H and
PtÃH bonds in platinum amine complexes and
/
particularly whether the relative labilities could be
reversed. From the point of view of NMR studies
compounds containing trans-labilizing ligands, tr,
such as p-C2H4, dCH2, . . ., CO and PPh3, are
particularly instructive as reaction and relaxation
rates are of the same general order. It is complexes
of the type, trans-[PtCl2(tr)(am)], which are stu-
died before [19]. Use is made of a phenomenon
2.3. Inequivalent CpCH2NR
The NÃ
/
H bond of many primary and secondary
amines is labile on an NMR time scale 18a. The
lability can be lowered by reduction of the basicity

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/
Fig. 2. 1H NMR spectrum of (h5-C5H4)Fe(h5-C5H4CH2NHCH2Ph)] in CDCl3 solution.
Fig. 3. 1H NMR spectrum of trans-[PtCl2(h2-C2H4)(h5-C5H5)Fe(h5-C5H4CH2NHCH2Ph)] in CDCl3 solution.

I.M. Al-Najjar et al. / Spectrochimica Acta Part A 59 (2003) 1265ꢂ
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1273
Fig. 4. 1H NMR spectrum of trans-[PtCl2(h2-C2H4)(h5-C5H4)Fe(h5-C5H4CH2NDCH2Ph)] in CDCl3 solution (ꢁ
D2O).
/
which appears to have passed unobserved in
platinumꢂamine complexes, namely that of possi-
proton of NÃ
/
CH3 signal appears as a doublet
peak at d 2.70, indicating that these protons are
/
3
ble inequivalence of PtNHCH2 protons due to
asymmetry at the N and C atoms. In theory the
two NCH2 protons in trans-[PtCl2(h2-C2H4){(h5-
C5H5)Fe(h5-C5H4CH2NHR)}] and [PtCl2(h2-
C2H4){(h5-C5H5)Fe(h5-C5H4CH2NDR)}] are not
equivalent [25].
coupled with NÃ
/
H proton, JNH ÃCH
ꢀ/5.86 Hz
(compared with NÃ
/
CH3 signal in free ligand, a
single peak appears at d 2.45 (Table 2)), and
flanked by platinum-195 satellites (33%),
3J(195Ptꢂ1
/
H)ꢀ26 Hz (Fig. 1). The CpCHAHBNH
/
protons appear as a simple two doublets of
doublets at d 3.75 and 4.35 downfield compared
with one single peak in free ligand (d 3.50, Table
2), and flanked by platinum-195 satellites,
In analyzing spectra of NCH2 protons in free
amines (CpCH2NHR) (Rꢀ
only one single peak was observed at d 3.4ꢂ
(the rest of the 1H NMR spectra is unremarkable).
In complexes, the spectra of CpCH2NHÃR, the
, protons give an AB pattern so that the CH2
/aliphatic or aromatic),
/4.0
3J(195Ptꢂ1
/
H)ꢀ34 Hz. The two doublets of doub-
/
/
lets indicate that the two protons of methylene
CH2Ã
/
group (CHAHBNH), are not equivalent and
protons ought to be inequivalent. The CH2N
protons appear as a simple two doublets of
coupled to NH proton 3J(NHÃ
/
CH)ꢀ
and coupled to each other (geminal coupling)
HB)ꢀ13.19 Hz. Treatment of the NMR
/7.33 Hz,
doublets at d 3.7ꢂ
/
4.4 downfield compared with
CH2N signal in free ligand. Treatment with D2O
2J(HAÃ
/
/
chloroform solution with D2O improves the reso-
lution enabling two clear doublets to be seen with
improves the resolution enabling two clear doub-
1
lets to be seen. The H spectrum of complex 1,
1
platinum-195 satellite (Fig. 1b). The H chemical
Rꢀ
/
CH3, has been chosen as a model in order to
simplify the 1H NMR spectra (Table 3). The
shifts of other protons are simply identified and
listed in Table 3. Furthermore, the 1H NMR

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/
spectrum of free amine and complex 2 (i.e. B),
trans-[PtCl2{(h2-C2H4){(h5-C5H5)Fe(h5-C5H4Ã
CH2NHÃCH2Ph}] (where RꢀCH2Ph). Figs. 2ꢂ
show four doublets of doublets for h5-CpÃ
the free amine, there is no NH Ã
the rapid inversion at the N removes any asym-
metry preventing inequivalence in NHÃCH2 pro-
tons. On the other hand if the PtÃN bond is inert
and the NÃH link labile on a NMR time scale, any
PtNHCH2 resonance will exhibit platinum satel-
lites but not NH ÃCH coupling. It is normally
assumed that NH proton exchange is accompanied
by inversion resulting in a time averaged loss of
asymmetry at the nitrogen atom. Hence any
inequivalence in NCH2 protons is lost. Following
these thoughts, we have searched these trans-
[PtCl2(h2-ethene)(amine)] systems for this second
possibility, in this and previous studies [19], the
occurrence of platinum satellites in the PtNCH
/
CH coupling and
/
/
/
/
4
/
/
/
CHAHBNH and NHCHA?CHB?Ph), the two pro-
tons of each methylene group are not equivalent
and coupled to NH proton, and coupling with
platinum-195 was detected. Addition of D2O to
the NMR chloroform solution gives four doublets
representing the four different protons in both
methylene group, AB system.
/
/
1
It is noteworthy that the H NMR spectra of
reduced imine into amine and their platinum
complexes indicated that the free rotation of the
CpCH2Ã
2) was blocked after complexation (Fig. 3).
In free amine CpÃCH2ÃN, CH2 protons reso-
nate at 3.81 ppm (single peak) and NÃCH2ÃPh
resonate at 3.52 ppm (single peak), fast free
rotation prevent NÃH coupling with both CH2
(Fig. 2). In complexation (Fig. 3), the two protons
) become non-
/
N or NÃ
/
CH2Ph bonds (e.g. Rꢀ/CH2Ph,
resonance without NÃ
/
CH2 inequivalence, or
/
/
merely just without NH Ã
/CH coupling, but with-
/
/
out success.
/
3. Experimental
of the two methylene group (CH2Ã
/
equivalence. Under these circumstances, the reso-
nances for A and B protons (CpCHACHBN) and
3.1. General comments
A? and B? protons NÃ
geminal coupling, usually in the range of 12ꢂ
Hz, while the chemical shift between them
Dd(dHBÃdHA)ꢀ80 Hz.
The absorption of the two protons of (CpÃ
CHAHBÃN) shifted downfield, and show doublet
of doublet, HA, 4.01 ppm (dd), and dHB, 4.40 (dd)
and ÃNÃCHA?HB?ÃPh, HA?, 3.84 ppm (dd) and
HB?, 4.35 (dd) downfield shift accompanying with
NÃH coupling J(NH ÃCHA), J(NH ÃCHA?)ꢀ
5.36 and 6.36 Hz, respectively.
/
CHA?CHB?) will exhibit
All solvents were appropriately dried and de-
gassed prior to use under an atmosphere of
dinitrogen, and all operations were routinely
carried out under Schlenk condition utilizing a
dinitrogen atmosphere. The compounds ferroce-
necaraldehyde, amines, sodium borotetrahydride,
MgSO4 and Zeise salt were obtained from Aldrich
and Winlab and were used as supplied. Solvents
used were obtained from Aldrich Chemicals, THF,
hexane, benzene, and Et2O were distilled from
/
18
/
/
/
/
/
/
/
/
/
/
/
sodium benzophenone ketyl×
/CH2Cl2 and CHCl3
Evidence came from the addition of D2O to the
chloroform-d solution of the complex (Fig. 4), the
results spectra show that the absorption of
were distilled from CaH2.
3.2. Methods
2
(CHAHB) as doublets of doublets with J
/
(HAÃHB)
couplingꢀ
doublets and J(HA?ÃHB?)
D2O will change the ÃNÃ
The question raised by this study is the relative
ease of breaking PtÃNH and PtNÃH bonds in this
sort of amine complex. If the PtÃN bond is
sufficiently labil, the ligand-exchange will occur
[7ꢂ11,19], so that NMR phenomena due to any
NH protons are governed by their high lability in
/
12.20 Hz and (CHA?HB?) as doublets of
NMR spectra were recorded on a JEOL JNM-
EX 400 FT-NMR spectrometer using deuterium
internal lock. The 1H NMR chemical shifts are
reported in ppm with reference to residual protons
in deuteriated solvent at 399.937 MHZ. 13C{1H}
NMR chemical shift, are referenced to solvent
carbon resonances as internal standards at 100.574
MHz. Imines were prepared as described elsewhere
2
ꢀ
/
13.16 Hz). Addition of
/
/H proton by D (Fig. 4).
/
/
/
/
[6ꢂ11]. The Pt complexes were dissolved in CDCl3
/

I.M. Al-Najjar et al. / Spectrochimica Acta Part A 59 (2003) 1265ꢂ
/1275
1275
at 22 8C. Multiplicities are reported as (s) singlet,
(d) doublet, (dd) doublet of doublet, (t) triplet, (m)
multiplet, (br) broad, and (ov) overlapping. IR
References
[1] A. Togni, T. Hayashi (Eds.), Ferrocenes, Homogeneous
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spectra were recorded on a PerkinꢂElmer 1600
/
series FT-IR, spectrophotometer, using KBr pel-
lets for solid compounds. M.p. were measured
(uncorrected) with a Mel-Temp apparatus. Micro-
analysis for C, H, and N were carried out at
[2] P.D. Beer, Adv. Inorg. Chem. 39 (1992) 79; P.D. Beer,
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3.3. Preparation of amine compounds
3.
[5] P. Li, I.J. Scowen, J.E. Davies, M.A. Halcrow, J. Chem.
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[6] I.M. Al-Najjar, A.M. Abdulrahman, J.K. Al-Refai, L.A.
Al-Shabanah, L.A. Al-Mutabagani, Trans. Met. Chem.
(January 2002) accepted for publication.
Thirty mmole of appropriate imine (CpCHÄ
R) in absolute methanol (30 ml) was cooled down
to ꢃ10 8C, 1.35 g (35 mmol) of NaBH4 was added
/
NÃ
/
/
and mixed together without stirring. The tempera-
ture of the mixture was allowed to rise to 25 8C
for 1 h. The solvent then was evaporated off and
distilled water (30 ml) and diethylether (150 ml)
were added to the residue. The mixture was shaken
in a separation funnel and the ether layer was
separated. The aqueous portion was washed with
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ether (2ꢄ30 ml). The ether extracts were pooled
and dried over sodium sulphate, then the solvent
was concentrated to 5 ml, after which light
/
[12] B.E. Mann, Adv. Organomet. Chem. 12 (1974) 134.
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petroleum ether (30ꢂ
added. Refrigeration afforded the compound as
redꢂbrown crystals (Table 1).
/
40 8C), 20 ml was slowly
/
[15] D.G. Cooper, J. Powell, Inorg. Chem. 15 (1976) 1959.
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3.4. Preparation of complexes
3.4.1. trans-[PtCl2{(h2-C2H4)(h5-C5H5)Fe(h5-
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C5H4Ã
/
CH2NHÃ
/
R)]
To (Zeise salt) K[PtCl3(h2-C2H4)] (400 mg, ca. 1
mmol) in H2O (10 ml) cooled to 1 8C, the amine
(ca. 1.1 mmol) dissolved in ice-cold H2O (2 ml)
(Table 1) was added slowly with stirring. The
mixture was cooled in ice and stirred for 10 min,
whereupon a yellow precipitate rapidly formed. To
enhance the yield, a few drops of Me2CO (or
MeOH) were added, to enhance the solubility of
the starting amine in water and force the amine
complex to precipitate. The yellow precipitate was
washed with cold H2O (ca. 2 ml) followed by
pentane (ca. 0.5 ml), and dried in vacuo. The
complexes were recrystallized from CHCl3; pen-
tane mixture (Table 1).
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