Metal complexes of biologically important ligands, CXIV ferrocenyl-oxazolones as N and C donors in Pd(II), Pt(II) and Ir(III) complexes and ferrocenoyl-dipeptides

Article abstract of DOI:10.1016/S0022-328X(99)00009-1

2-Ferrocenyl-4R-5(4H)-oxazolones 1-5 were obtained from N-ferrocenoyl-α-amino acids and function as N donors in dichloro-phosphine-palladium(II) and platinum(II) complexes 6-18. The reaction of ferrocenyl-oxazolone and ferrocenyl-bis(oxazolone) with [Cp*IrCl₂]₂ afforded trimetallic and pentametallic complexes 19 and 20 with a C,N bridging oxazolone. Ring opening of the ferrocenyl-oxazolones 1, 2 and 4 with α-amino acid esters gave N-ferrocenoyl-dipeptide esters 21-26. In the ferrocene bis(dipeptides) the two peptide esters are aligned parallel by hydrogen bonding. The structures of 6 and 19 were determined by X-ray diffraction.

Full text of DOI:10.1016/S0022-328X(99)00009-1

Journal of Organometallic Chemistry 579 (1999) 269–279
Metal complexes of biologically important ligands, CXIV
ferrocenyl–oxazolones as N and C donors in Pd(II), Pt(II) and Ir(III)
complexes and ferrocenoyl–dipeptidesꢀ
Werner Bauer, Kurt Polborn 1, Wolfgang Beck *
Institut fu¨r Anorganische Chemie, Ludwig–Maximilians-Uni6ersita¨t, Butenandtstraße 5–13, D-81377 Mu¨nchen, Germany
Received 11 November 1998
Abstract
2-Ferrocenyl-4R-5(4H)-oxazolones 1–5 were obtained from N-ferrocenoyl-a-amino acids and function as N donors in
dichloro–phosphine–palladium(II) and platinum(II) complexes 6–18. The reaction of ferrocenyl–oxazolone and ferrocenyl–
bis(oxazolone) with [Cp*IrCl2]2 afforded trimetallic and pentametallic complexes 19 and 20 with a C,N bridging oxazolone. Ring
opening of the ferrocenyl–oxazolones 1, 2 and 4 with a-amino acid esters gave N-ferrocenoyl–dipeptide esters 21–26. In the
ferrocene bis(dipeptides) the two peptide esters are aligned parallel by hydrogen bonding. The structures of 6 and 19 were
determined by X-ray diffraction. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: 2-Ferrocenyl-5(4H)-oxazolones; Ferrocenoyl marked dipeptides; C,N bridging oxazolone; Cyclic voltammetry
1. Introduction
their redox properties [9]. The 1,1%-ferrocenyl bis(ala-
nine) is available from 1,1%-diiodo–ferrocene [10].
Metal complexes of oxazolines have found great in-
terest as catalysts in asymmetric synthesis [2]. 5(4H)-
Oxazolones [3] are important starting materials; the
ease of racemisation [3,4] prevents their use in asym-
metric catalysis. However metal complexes of oxa-
zolones can provide information on the coordination
chemistry of N-heterocycles. Moreover ring opening
[5a] of organometallic oxazolones gives rise to peptides
attached to a metal. In continuation of our studies [5]
on oxazolone metal complexes we now report on the
synthesis and reaction of 2-ferrocenyl substituted
2. Synthesis of ferrocenyloxazolones
Ferrocenoyl-a-amino acid esters 1a–3a were synthe-
sized from ferrocene carboxylic acid and a-amino acid
esters, according to published procedures (Scheme 1,
[11a,12]). The first compounds of this type were re-
ported by Schlo¨gl [7a]. Erker’s [13] isocyanate route is
another access to cyclopentadienyl-a-amino acid ester
substituted metallocenes. Compounds 1a–3a were sa-
ponified and from the free acids 1b–3b the oxazolone
derivatives 1–3 could be obtained. Similary, the ferro-
cenylꢀbis(oxazolones) 4 and 5 were prepared from the
ferrocene dicarboxylic acid.
5(4H)-oxazolones
[6].
4-Ferrocenylmethylene-2-R-
5(4H) oxazolones are starting materials for the synthe-
sis of racemic [7] or optically active [8] ferrocenyl
alanine which was incorporated into peptides to follow
For compounds 1–5 the absorptions at 1820 cm−1
(CO) are characteristic in their IR-spectra [3]. Only for
complexes 3 and 5 the signals of the diastereotopic ring
protons (due to stereogenic C-4 oxazolone atoms) were
ꢀ Part 113, see Ref. [1].
* Corresponding author.
1 X-ray structure analyses.
1
observed in the H-NMR spectra. For 5 the two stereo-
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00009-1

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W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
Scheme 1.
genic centers give rise to two diastereoisomers (3:2)
which can be detected in the 1H- and 13C-NMR spectra.
inum complex [5c]. Obviously, in palladium(II) and
platinum(II) complexes with N and P donors the trans-
N–metal–P configuration is preferred as it was ob-
served for other complexes with P and N donors
[1,5b,c,15].
Remarkably, the reaction of 1 and 4 with the chloro
bridged halfsandwich iridium complex [Cp*IrCl2]2 leads
to a-metallation of the oxazolone ring to give the C, N
and chloro bridged trinuclear and pentanuclear com-
plexes 19 and 20. Recently, we reported an analogous
a-metallation with 2-phenylꢀoxazolone [5a]. Complex
19 contains three stereogenic centers; however only one
diastereoisomer (as enantiomeric pair RIrSCRIr% and
SIrRCSIr%) is formed from steric reasons. For com-
pounds 2, 3 and 5 which contain bulky substituents at
the oxazolone ring no reaction with [Cp*IrCl2]2 was
observed.
3. Reactions of ferrocenyloxazolones with chlorobridged
metal complexes
From 1–5 and chloro bridged palladium(II) and
platinum(II) complexes [R3PMCl2]2 the synthesis of a
series of N-coordinated oxazolone complexes 6–18 was
achieved (Scheme 2).
As was observed for complexes of 2-phenyl-5(4H)-
oxazolones the wCꢁO (wCꢁN) IR-absorptions are
shifted to higher (lower) wave numbers upon coordina-
1
tion. The H-NMR resonances of the ortho C5H4 pro-
tons show
a downfield shift [5b,c] due to the
1
The H- and 13C-NMR spectra of 20 exhibit two sets
paramagnetic anisotropy of the neighbouring metal
atoms [14] by about 0.9 ppm in average. As expected,
two sets of 1H- and 13C-NMR signals could be ob-
served for the compounds 17 and 18 which are formed
as diastereoisomers (oxazolone C-4: RS and RR/SS).
The structure of 6 was ascertained by X-ray structure
analysis (see Fig. 1) which shows the close proximity of
one ortho proton to the platinum atom. The Pt…H
of signals which we attribute to the two diastereoiso-
mers RIr1SC1RIr1%RIr2SC2RIr2% ꢀ SIr1RC1SIr1%SIr2RC2SIr2% and
R
Ir1SC1RIr1%SIr2RC2SIr2% (meso form). In the 1H-NMR
spectra of 19 and 20 the signals of the a-CH protons
are shifted downfield by 1.7 ppm upon metallation.
The crystal of 19 contained both enantiomers
RIrSCRIr% and SIrRCSIr% (Fig. 2). The molecular structure
is very similar to that of the diiridium complex with
2-phenyloxazolone [5a].
˚
distance was calculated as 2.865 A and is of the same
magnitude as found for a dimetallic oxazolone plat-

W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
271
Scheme 2.
Complex 23 is formed as mixture of two diastereoiso-
mers Ra-CSa-C and Sa-CSa-C (1:1) which are detected in
the 1H-NMR spectrum. In ferrocenyl bisdipeptide
derivatives the two dipeptide chains can align parallel
4. Formation of dipeptides from ferrocenyloxazolones
The covalently bound ferrocene moiety can act as
electron transfer relay between enzymes and metal elec-
trodes [16]. Different methods for the introduction of
the ferrocene unit into bio molecules were recently
examined [17]. The ferrocenyloxazolones 1, 2 and 4
provide another route to ferrocenoyl marked dipeptides
and the compounds 21–26 were obtained by nucle-
ophilic ring opening with a-amino acids2 (Scheme 3,
[3,18]).
1
by hydrogen bonds [19]. The H-NMR signals of the
two ferrocenoyl amide groups in 24–26 appear at l 8.5
while for 21–23 these resonances are found at l 6.4,
indicating hydrogen bonds (Fig. 3) between the two
peptide chains in 24–26 as was established by X-ray
structure determination for Fc(COalaproOEt)2 [19a].
In addition the w(NꢀH) IR absorptions in CH2Cl2 of
25 and 26 appear at 3410 cm−1 for the free NꢀH group
and at 3315 cm−1 for the NꢀH group involved in H
bridging [19,20] while 22 exhibits only one absorption
2 Compound 3 did not react with a-amino acid ester; 5 afforded a
mixture which was not separated.
at 3420 cm−1
.

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W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
5. Electrochemistry
For some compounds, cyclic voltammograms were
recorded and the electrochemical data are collected in
Table 1. We assume chemically reversible one-electron
transfer to occur, although the peak-to-peak separa-
tions sometimes showed distinct deviations from the
ideal value of 0.059 V. Since under the same conditions
for the ferroceneꢀferrocinium couple a separation of
0.206 V was observed (entry 9), we suppose that this is
due to the effects of uncompensated solution resistance
[21a]. In CH2Cl2 solutions such deviations were ob-
served earlier [21b]. Each oxazolone substituent in-
creases the formal electrode potential by about 0.3 V
(entries 1–3), while their coordination to platinum or
palladium had almost no influence (entries 4,5). Two
observations are difficult to explain: For compound 4
after three cycles an irreversible peak at 0.7 V occurred
and compound 6 showed after two cycles a new re-
versible couple at 0.430 V (separation 0.042 V) and
simultaneously an irreversible peak at 1.74 V. The
bridging oxazolone in 19 leads to an only 0.2 V higher
potential perhaps due to the greater deviation from
coplanarity of the oxazolone and cyclopentadienyl rings
disturbing their conjugation (entry 6). For the dipeptide
derivatives 23 and 25 potentials in the same range were
Fig. 2. Molecular structure of 19 (SIrRCSIr) in the crystal. Selected
bond lengths (A) and angles (°): Ir(1)ꢀN(1) 2.108(4), Ir(1)ꢀCl(1)
2.4320(14), Ir(2)ꢀC(3) 2.131(5), Ir(2)ꢀCl(1) 2.4289(14), N(1)ꢀC(1)
1.283(7), N(1)ꢀC(3) 1.470(6), C(1)ꢀC(4) 1.459(8), N(1)ꢀIr(1)ꢀCl(1)
83.84(12), Cl(2)ꢀIr(1)ꢀCl(1) 85.95(6), C(3)ꢀIr(2)ꢀCl(1) 82.32(14),
˚
Cl(3)ꢀIr(2)ꢀCl(1)
87.91(6),
Ir(2)ꢀCl(1)ꢀIr(1)
110.19(5),
C(1)ꢀN(1)ꢀC(3) 107.8(4), C(1)ꢀN(1)ꢀIr(1) 134.5(4), N(1)ꢀC(1)ꢀC(4)
131.9(5), C(2)ꢀC(3)ꢀIr(2) 115.8(4), N(1)ꢀC(3)ꢀIr(2) 115.6(3),
N(1)ꢀIr(1)ꢀC(l1)ꢀIr(2) ꢀ8.44(0.12), C(3)ꢀN(1)ꢀC(1)ꢀO(1) 2.07(0.59),
N(1)ꢀC(1)ꢀC(4)ꢀC(8) 29.93(1.04), Ir(1)ꢀN(1)ꢀC(3)ꢀIr(2) ꢀ72.29(0.38).
observed as were found for Fc(COalaproOEt) and Fc-
(COalaproOEt)2 [19a]. Each electron-withdrawing
amide function raised the value of the reversible oxida-
tion/reduction wave by about 0.2 V (entries 7,8).
Fig. 1. Molecular structure of 6 in the crystal. Selected bond lengths
˚
(A) and angles (°): Pt(1)ꢀN(1) 2.102(4), Pt(1)ꢀP(1) 2.232(2),
Fe(1)ꢀC(1) 2.021(5), N(1)ꢀC(11) 1.275(6), C(1)ꢀC(11) 1.442(7),
N(1)ꢀPt(1)ꢀP(1)
P(1)ꢀPt(1)ꢀCl(1)
177.08(11),
94.61(5),
N(1)ꢀPt(1)ꢀCl(2)
N(1)ꢀC(11)ꢀC(1)
87.88(11),
130.6(5),
O(1)ꢀC(11)ꢀC(1) 114.6(4), C(5)ꢀC(1)ꢀC(11)ꢀN(1) 170.09(0.49),
C(2)ꢀC(1)ꢀC(11)ꢀN(1) ꢀ14.51(0.81).
Scheme 3.

W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
273
mmol per carboxylic acid group) was treated with an
equimolar amount of triethylamine in 10 ml of CH2Cl2
and the mixture was added to the stirring slurry. Dicy-
clohexylurea precipitated almost immediately. Stirring
was continued at r.t. for 14–20 h and then the urea was
filtered off. The filtrate was washed with water (3×100
ml) and subsequently dried over MgSO4. After remov-
ing the solvent in vacuo the crude product was recrys-
tallized from EtOAc to give the ferrocenoyl amino acid
esters in 58–72% yield.
Fig. 3. Intramolecular hydrogen bonds in 24–26. For an X-ray
structure analysis of a similar compound see Ref. [19a].
6. Experimental
6.1.2. Method B (according to [12])
To a mixture of the appropriate ferrocenecarboxylic
acid (2 mmol), 1-(3%-dimethylaminopropyl)-3-ethylcar-
bodiimide (EDC) (2 mmol per carboxylic acid group),
the a-amino acid ester hydrochloric acid salt (2.3 mmol
per carboxylic acid group) and a catalytic amount of
dimethylaminopyridin (DMAP) (15 mg) in 25 ml of
CH2Cl2 4-methylꢀmorpholine (2.8 mmol per carboxylic
acid group) in 10 ml of CH2Cl2 was added dropwise
under N2 at r.t. The mixture was stirred for 1–3 days.
To the clear, red solution, 10 ml of saturated aqueous
ammonium chloride solution were added. The organic
layer was washed two times with 10 ml of water, dried
over MgSO4 and evaporated in vacuo to give the
ferrocenoyl amino acid esters reasonably pure in 73–
78% yield.
Most reactions were carried out in dry solvents under
nitrogen atmosphere using Schlenk-type glassware.
Melting points: Elektrothermal Digital Melting Point
Apparatus IA 8103. Melting points are not corrected.
IR: Nicolet 520 FT-IR or Perkin–Elmer 841. PE=
Polyethylene. NMR: Jeol GSX 270 or Jeol EX 400,
using the solvent as internal standard. Cyclic volta-
mograms: EG&G Potentiostat/Galvanostat Model 263
A. The starting materials were prepared according to
literature procedures ([nBu3PPtCl2]2 [22], [Et3PPtCl2]2
[22], [Et3PPdCl2]2 [23] [Cp*IrCl2]2 [24]). The a-amino
acid ester hydrochlorides were purchased from Merck
or Fluka, the ferrocenecarboxylic acids from Aldrich.
6.1. Ferrocenoyl amino acid esters 1a–5a
6.2. Ferrocenoyl amino acids 1b–5b
Two different methods could be employed for the
preparation:
The ferrocenoyl amino acid esters were dissolved in
ethanol (or in a mixture of ethanol and THF) and a
slight excess of 0.1 n NaOH was added slowly at 0°C
[7a]. The deep red solution was stirred for about 2–4 h
and then the organic solvents were distilled off. The
aqueous solution was cooled to 0°C and an equimolar
amount of 0.1 n HCl (to the amount of NaOH) was
added dropwise to precipitate the ferrocenoyl amino
acids which were collected, washed with water and
dried in vacuo at 50°C for several hours.
6.1.1. Method A (according to [11a])
A solution of the appropriate ferrocenecarboxylic
acid (2 mmol) in 10 ml of CH2Cl2 was treated with
solid dicyclohexylcarbodiimide (2.2 mmol per car-
boxylic acid group) and HOBt (equimolar to DCC).
The a-amino acid ester hydrochloric acid salt (2.3
Table 1
Electrochemical dataa
Entry
Compound
EPc
EPa
DEp
E0
6.3. 2-Ferrocenyl-5(4H)-oxazolones 1–5
1
2
3
4
5
6
7
8
9
2
3
4
6
11
19
23
25
0.546
0.568
0.833
0.598
0.546
0.423
0.470
0.660
0.230
0.738
0.678
0.940
0.698
0.662
0.630
0.650
0.774
0.436
0.192
0.110
0.057
0.100
0.116
0.207
0.180
0.114
0.206
0.642
0.623
0.912b
0.648c
0.604
0.527
0.560
0.717
0.333
The ferrocenoyl amino acids were suspended in
CH2Cl2 (about 5 ml per 1 mmol amino acid group). At
0°C a solution of an equimolar amount DCC (to the
amino acid groups) in CH2Cl2 (about 2 ml per 1 mmol
amino acid group) was added dropwise. After 6–14 h
stirring at r.t. the precipitated urea was filtered off and
washed twice with an small amount of CH2Cl2. The
combined solutions were concentrated in vacuo and
added to an excess of pentane whereby the products
precipitated. The products were centrifuged off, washed
twice with pentane and dried in vacuo at 50°C (except
for 1 which is slightly unstable) for about 8 h to afford
the corresponding 2-ferrocenyl-5(4H)-oxazolones 1–5.
Ferrocene
a Potentials are given in V versus Ag ꢀ AgCl; in CH2Cl2; 0.1 M
[nBu4N][PF6]; 20°C; Au electrode; Sweep rate 0.100 V s−1
.
b After three cycles an irreversible peak at 0.7 V occurred.
c After two cycles a new reversible couple appeared at 0.430 V with
a peak separation of 0.042 V. Simultaneously an irreversible peak at
1.74 V was observed.

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W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
1: 1.00 g (4.35 mmol) of ferrocenecarboxylic acid and
5: 1.00 g (3.65 mmol) of ferrocenedicarboxylic acid
and 1.291 g (8.40 mmol) of alanine methyl ester hy-
drochloride were used according to method B. Orange
powder, yield: 517 mg (37%). Diastereoisomeric ratio
3:2 (pair of enantiomers (S,S) (R,R) and meso product
(R,S)). m.p.: 107–108°C (red). IR (KBr): w˜ =1820
cm−1 vs (CꢁO), 1661 vs (CꢁN), 1628 m (CꢁC), 515 m,
0.70 g (5.02 mmol) of glycine ethyl ester hydrochloride
were used according to method A. Brown powder,
yield: 374 mg (32%). IR (KBr): w˜ =1831 cm−1 vs
(CꢁO), 1652 vs (CꢁN), 1629 s (CꢁC), 506 m, 496 m, 484
1
m (Fe–C). H-NMR (270 MHz, CDCl3): l 4.21 (s, 2H,
3
NCH2CO), 4.22 (s, 5H, Cp), 4.47 („t, J=4J=2.0 Hz,
3
2H, Cp-3,3%), 4.82 („t, J=4J=2.0 Hz, 2H, Cp-2,2%).
1
505 m, 494 m (Fe–C). H-NMR (270 MHz, CDCl3): l
13C-NMR (100.5 MHz, CDCl3): l 54.91 (NCH2CO),
68.03 (Cp-1), 68.80/71.52 (Cp-2,3), 70.06 (Cp), 166.83
(OCꢁN), 176.37 (CꢁO). C13H11NFeO2 (269.1):
Anal.Calc. C 58.03, H 4.12, N 5.21; Found C 57.70, H
4.51, N 5.35.
1.55/1.56 (each d, 3J=7.2 Hz, 3H, CH3), 4.28/4.30
3
(each q, J=7.5 Hz, 1H, NCH(R)CO), 4.54 (m, 4H,
Cp-3,3%), 4.84/4.89 (each m, each 2H, Cp-2,2%). 13C-
NMR (100.5 MHz, CDCl3): l 16.85/16.94 (CH3),
60.70/60.74 (NCH(R)CO), 69.90 (Cp-1), 70.65 (inten-
sity of two signals)/70.86/70.92 (Cp-2,2%), 72.56/72.80/
2: 1.00 g (4.35 mmol) of ferrocenecarboxylic acid and
0.764 g (4.97 mmol) of alanine ethyl ester hydrochloride
were used according to method B. Orange powder,
yield: 583 mg (47%). m.p.: 194–196°C (black). IR
(KBr): w˜ =1817 cm−1 vs (CꢁO), 1656 vs (CꢁN), 1628 m
(CꢁC), 503 s, 487 m (Fe–C). 1H-NMR (400 MHz,
72.96/73.16
178.71/178.77
(Cp-3,3%),
(CꢁO).
163.03/163.10
C18H16N2FeO4
(OCꢁN),
(380.2):
Anal.Calc. C 56.87, H 4.24, N 7.37; Found C 57.29, H
4.63, N 7.52.
3
CDCl3): l 1.51 (d, J=7.4 Hz, 3H, CH3), 4.19 (s, 5H,
6.4. General procedure for the preparation of 6–18
3
Cp), 4.23 (q, J=7.4 Hz, 1H, NCH(R)CO), 4.45 (m,
2H, Cp-3,3%), 4.81 (m, 2H, Cp-2,2%). 13C-NMR (100.5
MHz, CDCl3): l 17.24 (CH3), 66.79 (NCH(R)CO),
67.91 (Cp-1), 68.85/68.82 (Cp-2,2%), 70.09 (Cp), 71.53
(Cp-3,3%), 164.86 (OCꢁN), 179.31 (CꢁO). C14H13NFeO2
(283.1): Anal.Calc. C 59.40, H 4.63, N 4.95; Found C
59.61, H 4.94, N 5.35.
A solution of the appropriate chlorobridged tri-
alkylphosphine complex in CH2Cl2 was treated with a
slight excess of the corresponding 2-ferrocenyl-5(4H)-
oxazolone 1–5. After 3–4 h stirring at r.t., the solution
was concentrated in vacuo and an excess of diethylether
was added. The precipitate was centrifuged off and the
solution was evaporated. The residue was taken up in
CH2Cl2 and added dropwise to an excess of pentane.
The product precipitated either immediately (a) or on
concentrating the mixture (after adding hexane) in
vacuo (b). The precipitate was centrifuged off, washed
twice with pentane and dried in vacuo at 50°C for
several hours.
3: 1.00 g (4.35 mmol) of ferrocenecarboxylic acid and
1.072 g (4.97 mmol) of phenylalanine methyl ester
hydrochloride were used according to method A. Or-
ange powder, yield: 575 mg (37%). m.p.: 103–105°C
(red). IR (KBr): w˜ =1811 cm−1 vs (CꢁO), 1658 vs
1
(CꢁN), 1628 w (CꢁC), 504 s, 487 s (Fe-C). H-NMR
3
2
(400 MHz, CDCl3): l 3.26 (dd, J=4.7 Hz, J=14.1
3
2
Hz, 1H, CHH%Ph), 3.35 (dd, J=4.7 Hz, J=14.1 Hz,
1H, CHH%Ph), 3.93 (s, 5H, Cp), 4.39/4.41 (each m, each
1H, Cp-3,3%), 4.52 (t br, J=4.7 Hz, 1H, NCH(R)CO),
6: 36 mg (0.134 mmol) of 1 and 62 mg (0.066 mmol)
of [nBu3PPtCl2]2 were used. According to B, orange
powder, yield: 85 mg (87%). For X-ray structure analy-
sis suitable crystals were grown in a CH2Cl2/hexane
mixture. m.p.: 122°C (red). IR (KBr): w˜ =1861 cm−1 s,
1841 vs (CꢁO), 1654 sh, 1640 vs (CꢁN), 506 s, 497 s,
3
4.68/4.76 (each s br, each 1H, Cp-2,2%), 7.28 (m, 5H,
Ph). 13C-NMR (100.5 MHz, CDCl3): l 36.78 (CH2Ph),
66.31 (NCH(R)CO), 68.06/69.23 (Cp-2,2%), 69.95 (Cp),
71.16/71.43 (Cp-3,3%), 127.50 (Ph-4), 128.53/129.98 (Ph-
2,2%,3,3%), 135.58 (Ph-1), 164.96 (OCꢁN), 177.99 (CꢁO).
C20H17NFeO2 (359.2): Anal.Calc. C 66.88, H 4.77, N
3.90; Found C 66.14, H 4.86, N 4.20.
4: 1.00 g (3.65 mmol) of ferrocenedicarboxylic acid
and 1.061 g (7.60 mmol) of glycine ethyl ester hy-
drochloride were used according to method A. Brown
powder, yield: 419 mg (33%). m.p.: 135–138°C (red).
IR (KBr): w˜ =1820 cm−1 vs (CꢁO), 1666 vs, 1658 sh
(CꢁN), 1627 s (CꢁC), 511 m, 496 m, 483 m (Fe–C).
1H-NMR (270 MHz, CDCl3): l 4.23 (s, 4H, NCH2CO),
1
486 s (Fe–C), (in PE): 345 w (Pt–Cl). H-NMR (270
3
MHz, CDCl3): l 0.98 (t, 9H, J=7.2 Hz, nBu–CH3),
1.50/1.67/1.89 (each m, each 6H, 3×nBu–CH2), 4.35
(s, 5H, Cp), 4.49 (s, 2H, NCH2CO), 4.63 (m, 2H,
Cp-3,3%), 5.71 (m, 2H, Cp-2,2%). 13C-NMR (67.9 MHz,
1
CDCl3): l 13.89 (nBu–CH3), 21.44 (d, JCP=39.4 Hz,
2
nBu–CH2), 24.17 (d, JCP=14.1 Hz, nBu–CH2), 25.94
3
(d, JCP=2.9 Hz, nBu–CH2), 53.92 (NCH2CO), 63.69
(Cp-1), 70.86 (Cp), 71.32/73.07 (Cp-2,2%,3,3%), 170.64
(OCꢁN), 170.82 (CꢁO). 31P-NMR (109.4 MHz, CDCl3):
l −6.10 (s, 1JPPt=3499 Hz). C25H38NCl2FeO2PPt
(737.4): Anal.Calc. C 40.72, H 5.19, N 1.90; Found C
40.30, H 4.94, N 1.78.
7: 43 mg (0.160 mmol) of 1 and 57 mg (0.074 mmol)
of [Et3PPtCl2]2 were used. According to B, orange
powder, yield: 73 mg (76%). m.p.: 139°C (black). IR
3
3
4.52 („t, J=4J=2.0 Hz, 4H, Cp-3,3%), 4.87 („t, J=
4J=2.0 Hz, 4H, Cp-2,2%). 13C-NMR (100.5 MHz,
CDCl3): l 54.82 (NCH2CO), 70.10 (Cp-1), 70.84/72.93
(Cp-2,2%,3,3%), 164.95 (OCꢁN), 175.93 (CꢁO).
C16H12N2FeO4 (352.1): Anal.Calc. C 54.58, H 3.44, N
7.96; Found C 55.50, H 3.81, N 8.26.

W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
275
(KBr): w˜ =1863 cm−1 s, 1839 vs (CꢁO), 1639 vs (CꢁN),
PEt–CHH%), 1.96 (dquint, 3H, 3JHH=2JHP=7.6 Hz,
2JHH%=3.1 Hz, PEt–CHH%), 4.35 (s, 5H, Cp), 4.66 (q,
1H, J=7.5 Hz, NCHCH3), 4.63/4.66 (each m, each
504 w, 497 w, 483 w (Fe–C), (in PE): 345 w (Pt–Cl).
3
3
1H-NMR (400 MHz, CDCl3): l 1.26 (dt, 9H, JHH
=
7.7 Hz, 3JHP=17.2 Hz, PEt–CH3), 1.95 (dq, 6H,
1H, Cp-3,3%), 5.41/6.03 (each m, each 1H, Cp-2,2%).
3JHH=7.7 Hz, JHP=11.1 Hz, PEt–CH2), 4.36 (s, 5H,
13C-NMR (100.5 MHz, CDCl3): l 7.81 (d, JCP=3.2
2
2
1
Cp), 4.50 (s, 2H, NCH2CO), 4.65 (m, 2H, Cp-3,3%), 5.70
Hz, PEt–CH3), 14.04 (d, JCP=39.5 Hz, PEt–CH2),
(m, 2H, Cp-2,2%). 13C-NMR (67.9 MHz, CDCl3): l 7.78
17.24 (CHCH3), 60.66 (NCH(R)CO), 63.77 (Cp-1),
2
3
(d, JCP=2.9 Hz, JCPt=17.8 Hz, PEt–CH3), 14.12 (d,
1JCP=40.2 Hz, 2JCPt=33.8 Hz, PEt–CH2), 53.85
(NCH2CO), 63.67 (Cp-1), 70.88 (Cp), 71.29/73.16 (Cp-
2,2%,3,3%), 170.56 (OCꢁN), 170.94 (CꢁO). 31P-NMR
(109.4 MHz, CDCl3): l 1.49 (s, 1JPPt/3515 Hz).
C19H26NCl2FeO2PPt (653.2): Anal.Calc. C 34.94, H
4.01, N 2.14; Found C 35.15, H 3.75, N 2.19.
70.90 (Cp), 71.29/71.53 (Cp-2,2%), 73.02/73.26 (Cp-3,3%).
1
31P-NMR (109.4 MHz, CDCl3): l 1.63 (s, JPPt=3512
Hz). C20H28NCl2FeO2PPt (667.3): Anal.Calc. C 36.00,
H 4.23, N 2.10; Found C 36.90, H 4.30, N 2.36.
11: 46 mg (0.163 mmol) of 2 and 44 mg (0.074 mmol)
of [Et3PPdCl2]2 were used. According to A, orange
powder, yield: 63 mg (78%). m.p.: 128–131°C (red). IR
(KBr): w˜ =1830 vs (CꢁO), 1642 vs (CꢁN), 505 s, 489 m
8: 53 mg (0.197 mmol) of 1 and 53 mg (0.090 mmol)
of [Et3PPdCl2]2 were used. According to A, orange
powder, yield: 77 mg (76%). m.p.: 137°C (dark red). IR
(KBr): w˜ =1855 cm−1 s, 1834 vs (CꢁO), 1643 vs (CꢁN),
1
(Fe–C), (in PE): 354 w (Pd–Cl). H-NMR (270 MHz,
3
3
CDCl3): l 1.31 (dt, 9H, JHH=7.6 Hz, JHP=17.7 Hz,
PEt–CH3), 1.99 (dq, 6H, 3JHH=7.4 Hz, 2JHP=11.7
Hz, PEt–CH2), 1.84 (d, 3H, J=7.2 Hz, CHCH3), 4.33
3
504 w, 497 w, 484 w (Fe–C), (in PE): 356 w (Pd-Cl).
3
1H-NMR (400 MHz, CDCl3): l 1.32 (dt, 9H, JHH
=
(s, 5H, Cp), 4.61 (m, 3H, NCHCH3 and Cp-3,3%),
5.38/5.81 (each m, each 1H, Cp-2,2%). 13C-NMR (100.5
MHz, CDCl3): l 8.21 (d, 2JCP=3.2 Hz, PEt–CH3),
7.6 Hz, 3JHP=17.8 Hz, PEt–CH3), 2.00 (dq, 6H,
3JHH=7.6 Hz, JHP=11.3 Hz, PEt–CH2), 4.35 (s, 5H,
2
1
Cp), 4.46 (s, 2H, NCH2CO), 4.63 (m, 2H, Cp-3,3%), 5.60
15.99 (d, JCP=34.2 Hz, PEt–CH2), 17.46 (CHCH3),
(m, 2H, Cp-2,2%). 13C-NMR (67.9 MHz, CDCl3): l 8.18
60.32 (NCH(R)CO), 64.54 (Cp-1), 70.82 (Cp), 70.95/
71.08 (Cp-2,2%), 72.81/72.90 (Cp-3,3%), 168.48 (OCꢁN),
174.95 (CꢁO). 31P-NMR (109.4 MHz, CDCl3): l 36.79.
C20H28NCl2FeO2PPd (546.6): Anal. Calc. C 41.52, H
4.88, N 2.42; Found C 41.99, H 4.94, N 2.58.
2
1
(d, JCP=2.8 Hz, PEt–CH3), 16.11 (d, JCP=33.3 Hz,
PEt–CH2), 53.74 (NCH2CO), 64.55 (Cp-1), 70.78 (Cp),
70.91/72.85 (Cp-2,2%,3,3%), 170.43 (OCꢁN), 171.57
(CꢁO). 31P-NMR (109.4 MHz, CDCl3): l 37.35 (s).
C19H26NCl2FeO2PPd (564.6): Anal. Calc. C 40.42, H
4.64, N 2.48; Found C 39.93, H 4.59, N 2.38.
12: 47 mg (0.131 mmol) of 3 and 49 mg (0.064 mmol)
of [Et3PPtCl2]2 were used. According to B, orange
powder, yield: 72 mg (76%). m.p.: 130°C (red). IR
(KBr): w˜ =1856 cm−1 m, 1834 vs (CꢁO), 1628 vs
(CꢁN), 504 w, 491 w, 482 w (Fe–C), (in PE): 341 w
9: 17 mg (0.060 mmol) of 2 and 27 mg (0.029 mmol)
of [nBu3PPtCl2]2 were used. According to B, orange
powder, yield: 28 mg (64%). IR (KBr): w˜ =1860 cm−1
sh, 1835 vs (CꢁO), 1632 vs (CꢁN), 509 m, 504 m, 486 m
1
(Pt–Cl). H-NMR (400 MHz, CD2Cl2): l 1.25 (dt, 9H,
1
(Fe–C), (in PE): 340 w (Pt–Cl). H-NMR (270 MHz,
3JHH=7.5 Hz, 3JHP=17.3 Hz, PEt–CH3), 1.94 (dq,
6H, 3JHH=7.6 Hz, 2JHP=11.1 Hz, PEt–CH2), 3.52
3
CDCl3): l 0.98 (t, 9H, J=7.0 Hz, nBu–CH3), 1.45/
3
2
1.64/1.90 (each m, each 6H, 3×nBu–CH2), 1.83 (d,
(dd, 1H, J=6.1 Hz, J=14.5 Hz, CHH%Ph), 3.74 (dd,
3
3
2
3H, J=7.3 Hz, CHCH3), 4.33 (s, 5H, Cp), 4.63 (m,
1H, J=4.9 Hz, J=14.5 Hz, CHH%Ph), 4.27 (s, 5H,
Cp), 4.66 (m, 2H, Cp-3,3%), 5.04 („t, 1H, J:5.9 Hz,
3
3H, Cp-3,3% and NCH(R)CO), 5.38/6.07 (each m, each
1H, Cp-2,2%). 13C-NMR (67.9 MHz, CDCl3): l 13.92
CHCH2Ph), 5.47/5.94 (each m, each 1H, Cp-2,2%), 7.25
(ABB%CC%, 1H, Ph-4), 7.32 (BB% 2H, Ph-3,3%), 7.52 (CC%,
2H, Ph-2,2%). 13C-NMR (100.5 MHz, CD2Cl2): l 7.62
1
(nBu–CH3), 17.16 (CHCH3), 21.35 (d, JCP=39.2 Hz,
2
nBu–CH2), 24.18 (d, JCP=14.4 Hz, nBu–CH2), 26.02
(d, 3JCP=2.9 Hz, nBu–CH2), 60.66 (NCH(R)CO),
63.80 (Cp-1), 70.88 (Cp), 71.36/71.53 (Cp-2,2%), 72.91/
73.20 (Cp-3,3%), 169.19 (OCꢁN), 174.34 (CꢁO). 31P-
(d, JCP=3.1 Hz, PEt–CH3), 14.06 (d, JCP=41.3 Hz,
PEt–CH2), 36.33 (CH2Ph), 63.77 (Cp-1), 65.97
(NCH(R)CO), 70.86 (Cp), 71.47/71.51 (Cp-2,2%), 73.21/
73.29 (Cp-3,3%), 127.36 (Ph-4), 128.45/130.21 (Ph-
2,2%,3,3%), 135.09 (Ph-1), 169.99 (OCꢁN), 172.60 (CꢁO).
2
1
1
NMR (109.4 MHz, CDCl3): l −6.08 (s, JPPt=3501
Hz). C26H40NCl2FeO2PPt (751.4): Anal.Calc. C 41.56,
H 5.37, N 1.86; Found C 41.40, H 5.52, N 1.75.
10: 46 mg (0.163 mmol) of 2 and 57 mg (0.074 mmol)
of [Et3PPtCl2]2 were used. According to A, orange
powder, yield: 89 mg (90%). m.p.: 117–119°C (red). IR
(KBr): w˜ =1834 vs (CꢁO), 1638 vs (CꢁN), 505 m, 490 w
1
31P-NMR (109.4 MHz, CDCl3): l 1.88 (s, JPPt=3520
Hz). C26H32NCl2FeO2PPt (743.4): Anal.Calc. C 42.01,
H 4.34, N 1.88; Found C 42.01, H 4.41, N 2.04.
13: 48 mg (0.134 mmol) of 3 and 38 mg (0.064 mmol)
of [Et3PPdCl2]2 were used. According to B, orange
powder, yield: 68 mg (81%). m.p.: 121–122°C (red). IR
(KBr): w˜ =1850 cm−1 s, 1831 vs (CꢁO), 1632 vs (CꢁN),
1
(Fe–C), (in PE): 341 w (Pt–Cl). H-NMR (400 MHz,
3
3
CDCl3): l 1.27 (dt, 9H, JHH=7.6 Hz, JHP=17.2 Hz,
PEt–CH3), 1.85 (d, 3H, 3J=7.7 Hz, CHCH3), 1.94
503 m, 490 m, 480 w (Fe–C), (in PE): 353 w (Pd–Cl).
(dquint, 3H, 3JHH=2JHP=7.6 Hz, JHH%=3.1 Hz,
1H-NMR (400 MHz, CD2Cl2): l 1.29 (dt, 9H, JHH
=
2
3

276
W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
3
7.6 Hz, JHP=17.9 Hz, PEt–CH3), 1.98 (dq br, 6H,
vs (CꢁO), 1643 vs (CꢁN), 514 w, 493 w (FeꢀC), (in
3JHH=7.3 Hz, JHP=11 Hz, PEt–CH2), 3.57 (m br,
2
1
PE): 358 w (PdꢀCl). H-NMR (400 MHz, CDCl3): l
1.29 (dt, 18H, 3JHH=7.4 Hz, 3JHP=18.0 Hz,
PEtꢀCH3), 1.96 (s br, 12H, PEtꢀCH2), 4.51 (s, 4H,
NCH2CO), 4.80 (s br, 4H, Cp-3,3%), 5.74 (s br, 4H,
Cp-2,2%). 13C-NMR (67.9 MHz, CDCl3): l 8.15 (d,
2JCP=3.5 Hz, PEtꢀCH3), 16.28 (d, 1JCP=30.3 Hz,
PEtꢀCH2), 54.02 (NCH2CO), 67.34 (Cp-1), 73.04/74.97
(Cp-2,2%,3,3%), 168.87 (OCꢁN), 171.10 (CꢁO). 31P-NMR
2H, CH2Ph), 4.22 (s, 5H, Cp), 4.63 (s br, 2H, Cp-3,3%),
5.02 (s br, 1H, CHCH2Ph), 5.51/5.67 (each s br, each
1H, Cp-2,2%), 7.23 (ABB%CC%, 1H, Ph-4), 7.31 (BB%, 2H,
Ph-3,3%), 7.54 (CC%, 2H, Ph-2,2%). 13C-NMR (100.5
2
MHz, CD2Cl2): l 8.01 (d, JCP=3.9 Hz, PEt–CH3),
16.16 (d, 1JCP=33.7 Hz, PEt–CH2), 36.44 (CH2Ph),
64.64 (Cp-1), 65.84 (NCH(R)CO), 70.71 (Cp), 70.71/
70.93 (Cp-2,2%), 72.84/72.94 (Cp-3,3%), 127.36 (Ph-4),
128.43/130.36 (Ph-2,2%,3,3%), 135.08 (Ph-1), 169.38
(OCꢁN), 173.33 (CꢁO). 31P-NMR (109.4 MHz,
CDCl3): l 37.77 (s). C26H32NCl2FeO2PPd (654.7):
Anal. Calc. C 47.70, H 4.93, N 2.14; Found C 47.14, H
4.87, N 2.33.
(109.4 MHz, CDCl3):
l
38.21 (s). C28H42N2-
Cl4FeO4P2Pd2 · CH2Cl2 (1028.0): Anal. Calc. C 33.88,
H 4.31, N 2.72; Found C 33.97, H 4.49, N 2.62.
17: 23 mg (0.061 mmol) of 5 and 45 mg (0.059
mmol) of [Et3PPtCl2]2 were used. On adding di-
ethylether the product precipitated. The mixture was
evaporated and the residue dissolved in CH2Cl2. Ac-
cording to A, 58 mg of 17 were obtained after washing
with diethylether/CH2Cl2 (10:1) as a red powder (yield:
86%). Diastereomeric ratio 3:2. m.p.: 199–202°C
(black). IR (KBr): w˜ =1865 cm−1 m, 1835 s (CꢁO),
1639 vs (CꢁN), 511 w, 490 w (FeꢀC), (in PE): 344 w
14: 30 mg (0.085 mmol) of 4 and 77 mg (0.082
mmol) of [nBu3PPtCl2]2 were used. According to B, 71
mg of 14 were obtained after washing with di-
ethylether/CH2Cl2 (10:1) as an orange powder (yield:
65%). m.p.: 166°C (dark red). IR (KBr): w˜ =1864
cm−1 s, 1837 vs (CꢁO), 1640 vs (CꢁN), 505 w, 495 m
(Fe–C), (in PE): 347 w (Pt–Cl). H-NMR (270 MHz,
CDCl3): l 0.97 (t, 18H, J=7.3 Hz, nBu–CH3), 1.49/
1.64/1.86 (each m, each 12H, 3×nBu–CH2), 4.54 (s,
4H, NCH2CO), 4.81 („t, J=2.0 Hz, 4H, Cp-3,3%), 5.85
(„t, J=2.2 Hz, 4H, Cp-2,2%). 13C-NMR (100.5 MHz,
1
1
(PtꢀCl). H-NMR (270 MHz, CDCl3): l 1.27 (m, 18H,
3
3
PEtꢀCH3), 1.87 (d, 6H, J=7.2 Hz, CHCH3), 1.96 (m,
3
12H, PEtꢀCH2), 4.75 (q, 2H, J=7.4 Hz, NCHCH3),
4.82/4.85 (each m, 4H, Cp-3,3%), 5.55/5.69 (each m,
2H, Cp-2), 6.13/6.32 (each m, 2H, Cp-2%). 13C-NMR
(100.5 MHz, CDCl3): l 7.82 (d, 2JCP=3.4 Hz,
1
CDCl3): l 13.72 (nBu–CH3), 21.82 (d, JCP=39.8 Hz,
nBu–CH2), 24.01 (d, JCP=15.1 Hz, nBu–CH2), 25.58
2
1
PEtꢀCH3), 14.06 (d, JCP=39.9 Hz, PEtꢀCH2), 17.10/
(s, nBu–CH2), 54.14 (NCH2CO), 66.43 (Cp-1), 73.59/
17.13 (CHCH3), 60.84/60.66 (NCH(R)CO), 66.04/
66.15 (Cp-1), 73.30, 73.37/73.79, 73.89 (Cp-2,2%), 75.64,
75.68/75.73, 75.89 (Cp-3,3%), 167.99 (OCꢁN), 173.50/
173.55 (CꢁO). 31P-NMR (109.4 MHz, CDCl3): l 2.08/
75.22 (Cp-2,2%,3,3%), 169.41 (OCꢁN), 169.92 (CꢁO). 31P-
1
NMR (109.4 MHz, CDCl3): l −5.81 (s, JPPt=3518
Hz). C40H66N2Cl4FeO4P2Pt2 (1288.7): Anal. Calc. C
37.28, H 5.16, N 2.17; Found C 36.74, H 5.15, N 2.02.
15: 49 mg (0.139 mmol) of 4 and 107 mg (0.139
mmol) of [Et3PPtCl2]2 were used. According to A, 137
mg of 15 were obtained after washing with di-
ethylether/CH2Cl2 (10:1) as an orange powder (yield:
82%). m.p.: 180°C (black). IR (KBr): w˜ =1863 cm−1 s,
1841 vs (CꢁO), 1640 vs (CꢁN), 507 w, 497 w (FeꢀC),
1
2.11 (each s, JPPt=3521 Hz). C30H46N2Cl4FeO4P2Pt2
(1148.5): Anal. Calc. C 31.38, H 4.04, N 2.44; Found C
31.41, H 4.10, N 2.38.
18: 36 mg (0.095 mmol) of 5 and 50 mg (0.095
mmol) of [Et3PPdCl2]2 were used. As for 17 according
to A, 79 mg of 18 were obtained after washing with
diethylether/CH2Cl2 (10:1) as an orange powder (yield:
92%). Diastereomeric ratio 3:2. m.p.: 188–192°C
(black). IR (KBr): w˜ =1855 cm−1 s, 1831 s (CꢁO),
1644 vs (CꢁN), 512 m, 490 w (FeꢀC), (in PE): 356 m
1
(in PE): 345 w (PtꢀCl). H-NMR (270 MHz, CDCl3): l
1.24 (dt, 18H, 3JHH=7.5 Hz, 3JHP=17.2 Hz,
3
2
PEtꢀCH3), 1.92 (dq, 12H, JHH=7.6 Hz, JHP=11.0
Hz, PEtꢀCH2), 4.54 (s, 4H, NCH2CO), 4.82 („t, 4H,
Cp-3,3%), 5.86 („t, 4H, Cp-2,2%). 13C-NMR (67.9 MHz,
1
(PdꢀCl). H-NMR (270 MHz, CDCl3): l 1.32 (dt, 18H,
3
3JHH=7.5 Hz, JHP=17.6 Hz, PEtꢀCH3), 1.87 (d, 6H,
2
CDCl3): l 7.78 (d, JCP=2.9 Hz, PEtꢀCH3), 14.10 (d,
3J=7.7 Hz, CHCH3), 2.00 (m, 12H, PEtꢀCH2), 4.67
1JCP=40.7 Hz, PEtꢀCH2), 54.11 (NCH2CO), 66.38
(Cp-1), 73.47/75.40 (Cp-2,2%,3,3%), 167.30 (OCꢁN),
169.98 (CꢁO). 31P-NMR (109.4 MHz, CDCl3): l 1.88
(s, 1JPPt=3527 Hz). C28H42N2Cl4FeO4P2Pt2 · CH2Cl2
(1205.3): Anal. Calc. C 28.90, H 3.68, N 2.32; Found C
29.02, H 3.62, N 2.28.
3
(q, 2H, J=7.6 Hz, NCHCH3), 4.78/4.83 (each s br,
4H, Cp-3,3%), 5.50/5.64 (each s br, 2H, Cp-2), 5.94/6.13
(each s br, 2H, Cp-2%). 13C-NMR (100.5 MHz, CDCl3):
2
1
l 8.22 (d, JCP=3.2 Hz, PEtꢀCH3), 16.05 (d, JCP
=
34.2 Hz, PEtꢀCH2), 17.35 (CHCH3), 60.50/60.57
(NCH(R)CO), 66.80/66.92 (Cp-1), 73.04/73.30 (Cp-
2,2%), 75.41 (Cp-3,3%), 167.18 (OCꢁN), 174.24 (CꢁO).
16: 35 mg (0.099 mmol) of 4 and 59 mg (0.099
mmol) of [Et3PPdCl2]2 were used. According to A, 57
mg of 16 were obtained after recrystallisation from
CH2Cl2/pentane as an orange powder (yield: 56%).
m.p.: 205°C (black). IR (KBr): w˜ =1856 cm−1 s, 1838
31P-NMR (109.4 MHz, CDCl3):
l
37.73 (s).
C30H46N2Cl4FeO4P2Pd2 (971.2): Anal. Calc. C 31.38, H
4.04, N 2.44; Found C 31.41, H 4.10, N 2.38.

W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
277
6.5. General procedure for the preparation of 19 and
20
salt was suspended in CH2Cl2. An equimolar amount of
NaOMe (methanolic solution) was added. The clear
solution (for glycine ester hydrochloride 5 ml of MeOH
had to be added) was stirred for 10 min. Then the
2-ferrocenyl-5(4H)-oxazolone was added and the mix-
ture was stirred until the characteristic IR-absorption of
A solution of the chlorobridged complex [Cp*IrCl2]2
in CH2Cl2 was treated with a slight excess of the
appropriate 2-ferrocenyl-5(4H)-oxazolone 1 or 4 and
solid NaOAc. After stirring for 14 h (19) or 30 h (20) the
mixture was evaporated and dried in vacuo for 3 h. The
residue was taken up in CH2Cl2 and filtered through
Celite to remove NaCl. The solution was evaporated and
dried again. A concentrated solution of the residue in
CH2Cl2 was added dropwise to an excess of pentane
whereby the product precipitated (20). For 19 the mix-
ture has to be concentrated in vacuo to complete the
precipitation. The product was centrifuged off, washed
twice with pentane and dried in vacuo at 50°C for several
hours.
the oxazolone carboxyl group (at about 1820 cm−1
)
disappeared. The solution was then evaporated and the
residue was dried in vacuo for 2 h. It was dissolved in
CH2Cl2 and the solution was filtered through Celite to
remove NaCl. For complete removal of NaCl the solu-
tion was centrifuged for several min. If NaCl still
remained, it was pelleted on the bottom of the Schlenk
tube and the solution could be transferred into another
tube. It was concentrated in vacuo to about 1 ml and
added dropwise at 0°C to an excess of pentane whereby
the product precipitated. The precipitate was centrifuged
off, washed twice with cold pentane and dried in vacuo
at r.t. for several days.
19: 50 mg (0.186 mmol) of 1, 130 mg (0.163 mmol) of
[Cp*IrCl2]2 and 15 mg of NaOAc (0.183 mmol) were
used. Orange powder, yield: 138 mg (82%). For X-ray
structure analysis suitable crystals were grown in a
CH2Cl2/pentane mixture. m.p.: 252°C (dec.). IR (KBr):
w˜ =1794 cm−1 vs (CꢁO), 1606 vs (CꢁN), 510 w, 490 w
21: 33 mg (0.122 mmol) of 1 and 17 mg (0.122 mmol)
of glycine ethyl ester hydrochloric acid salt were used.
After stirring for 3 d 21 was obtained as a yellow oil. IR
(CH2Cl2): w˜ =1746 cm−1 vs (COOR), 1661 vs (amide I),
1515 vs (amide II). 1H-NMR (270 MHz, CDCl3): l 1.27
(t, 3J=7.1 Hz, 3H, OCH2CH3), 4.07 (d, 3J=7.8 Hz, 2H,
1
(FeꢀC), (in PE): 302 w, 265 w (IrꢀCl). H-NMR (400
MHz, CDCl3): l 1.39 (s, 15H, Cp*ꢀCH3), 1.69 (s, 15H,
Cp*ꢀCH3), 4.30 (s, 5H, Cp), 4.42 (m, 1H, Cp-3), 4.47 (m,
1H, Cp-3%), 4.86 (m, 1H, Cp-2), 5.95 (s, 1H, NCHIrCO),
6.09 (m, 1H, Cp-2%). 13C-NMR (100.5 MHz, CDCl3): l
8.96/9.13 (Cp*ꢀCH3), 66.78 (NCHIrCO), 70.09 (Cp),
70.60 (Cp-1), 70.28/70.90/71.08/72.22 (Cp-2,2%,3,3%),
86.83/86.99 (Cp*ꢀC), 164.41 (OCꢁN), 180.80 (CꢁO).
C33H40NCl3FeIr2O2 (1029.33): Anal. Calc. C 38.51, H
3.92, N 1.36; Found C 38.30, H 3.94, N 1.28.
3
NHCH2), 4.09 (d, J=7.8 Hz, 2H, NHCH2), 4.18 (q,
3J=7.1 Hz, 2H, OCH2CH3), 4.22 (s, 5H, Cp), 4.36 (m,
2H, Cp-3,3%), 4.69 (m, 2H, Cp-2,2%), 6.34 (br, 1H,
NHCH2), 6.59 (br, 1H, NHCH2). C17H20N2FeO4 · 0.85
CH2Cl2 (444.4): Anal. Calc. C 48.24, H 4.92, N 6.30;
Found C 48.23, H 5.06, N 6.41.
22: 28 mg (0.104 mmol) of 1 and 15 mg (0.108 mmol)
of alanine methyl ester hydrochloric acid salt were used.
The reaction mixture was stirred for 6 h. For further
purification a hot solution in EtOAc was filtered and
evaporated. The residue was taken up in CH2Cl2 and
precipitated and washed as above. Yellow powder. IR
(CH2Cl2): w˜ =3421 cm−1 m (NH); (KBr): 3402 s br, 3298
s br (NH), 1745 vs (COOR), 1656 sh, 1638 vs (amide I),
1539 vs (amide II), 500 m, 486 m (FeꢀC). 1H-NMR (270
MHz, CDCl3): l 1.44 (d, 3J=7.0 Hz, 3H, CH3), 3.74 (s,
3H, OCH3), 4.08 (m, 2H, NHCH2), 4.22 (s, 5H, Cp), 4.36
20: 42 mg (0.119 mmol) of 4, 180 mg (0.226 mmol) of
[Cp*IrCl2]2 and 19 mg of NaOAc (0.232 mmol) were
used. 106 mg of 20 were obtained after recrystallisation
from a CH2Cl2/pentane mixture as an orange powder
(yield: 46%). Two diastereoisomers. Diastereoisomeric
ratio 1.1:1. m.p.: 240°C (dec.). IR (KBr): w˜ =1794 cm−1
vs (CꢁO), 1606 vs (CꢁN), 512 w (FeꢀC), (in PE): 296 w,
266 w (IrꢀCl). 1H-NMR (400 MHz, CDCl3): l 1.38/1.40
(each s, 30H, Cp*ꢀCH3), 1.69/1.70 (each s, 30H,
Cp*ꢀCH3), 4.61 (m, 2H, Cp-3), 4.68 (m, 2H, Cp-3%),
4.93/4.98 (each m, 2H, Cp-2), 5.97/5.98 (each s, 2H,
NCHIrCO), 6.17/6.22 (each m, 2H, Cp-2%). 13C-NMR
(67.9 MHz, CDCl3): l 9.16/9.42/9.09 (Cp*ꢀCH3), 66.75/
66.87 (NCHIrCO), 71.58/72.07/72.30/72.38/73.03/73.09/
3
(m, 2H, Cp-3,3%), 4.59 (dq, JH(CH)=3JH(NH)=7.2 Hz,
1H, NHCHCH3), 4.71 (m, 2H, Cp-2,2%), 6.50 (br, 1H,
NHCH2), 6.90 (d br, 3J=7.4 Hz, 1H, NHCHCH3).
C17H20N2FeO4×0.2 CH2Cl2 (389.2): Anal. Calc. C
53.08, H 5.28, N 7.20; Found C 53.16, H 5.83, N 7.17.
23: 56 mg (0.198 mmol) of 2 and 27 mg (0.193 mmol)
of alanine methyl ester hydrochloric acid salt were used.
After 14 h stirring 23 was obtained as a yellow powder.
Two diastereoisomers. Diastereoisomeric ratio 1:1. m.p.:
124–126°C (red). IR (KBr): w˜ =3281 cm−1 vs
(NH), 1756 vs (COOR), 1669 vs, 1641 vs, 1629 vs
(amide I), 1544 vs, 1538 vs (amide II), 496 s, 484 s
73.27/73.46/73.55
(Cp-2,2%,3,3%),
86.95/87.02/87.06
(Cp*ꢀC), 162.70/162.80 (OCꢁN), 180.16/180.34 (CꢁO).
C56H70N2Cl6FeIr4O4×1.75 CH2Cl2 (2021.3): Anal.
Calc. C 34.32, H 3.67, N 1.39; Found C 34.18, H 3.69,
N 1.24.
1
3
6.6. General procedure for the preparation of 21–26
The appropriate a-amino acid ester hydrochloric acid
(FeꢀC). H-NMR (400 MHz, CDCl3): l 1.44 (d, J=
7.0 Hz, 3H, CH(CH3)COOCH3), 1.45/1.46 (each d,
3J=7.1 Hz, 3H, CH(CH3)CONH), 3.72/3.76 (each s,

278
W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
Table 2
br, 4H, Cp-2,2%), 6.83 (m, 2H, NHCH2COOCH3), 8.48
(m, 2H, NHCH2CONH). C22H26N4FeO8×0.1 CH2Cl2
(538.8): Anal. Calc. C 49.26, H 4.90, N 10.40; Found C
49.23, H 4.71, N 10.35.
Crystal data and structure refinement for 6 and 19
Compound number
6 (M1763)a
19 (M1839)
Empirical formula
Formula weight
Temperature (K)
Crystal system
C25H38Cl2FeNO2PPt
737.37
295(2)
Monoclinic
P21/c (Nr.: 14)
C33H40Cl3FeIr2NO2
1029.26
294(2)
Triclinic
P1 (Nr.: 2)
25: 50 mg (0.142 mmol) of 4 and 39 mg (0.279 mmol)
of alanine methyl ester hydrochloric acid salt were used.
After 24 h stirring 25 was obtained as a slightly brown
powder. m.p.: 218°C (dec.). IR (CH2Cl2): w˜ =3410
cm−1 m, 3310 m (NH); (KBr): 3286 vs br (NH), 1740
vs (COOR), 1668 vs, 1639 vs (amide I), 1548 vs (amide
II), 495 m (Fe–C). 1H-NMR (270 MHz, CDCl3): l 1.47
Space group
Unit cell dimensions
˚
a (A)
9.852(3)
13.575(4)
22.093(6)
10.621(3)
12.1012(13)
14.892(2)
70.631(10)
80.64(2)
66.282(14)
1652.2(5)
2
b
c
h (°)
i
3
(d, J=7.2 Hz, 6H, CHCH3), 3.75 (s, 6H, OCH3), 3.79
(dd, 3J=6.2 Hz, 2J=16.0 Hz, 2H, NHCHH%), 4.04
101.43(2)
3
2
(dd, J=6.2 Hz, J=15.7 Hz, 2H, NHCHH%), 4.38 (s
br, 2H, Cp-3), 4.44 (s br, 2H, Cp-3%), 4.59 („quint,
3JH(CH)=3JH(NH)=6.7 Hz, 2H, NHCHCH3), 4.83 (s br,
k
3
˚
Volume (A )
Z
2896.1(15)
4
1.691
Density (calculated)
2.069
3
4H, Cp-2,2%), 6.59 (d, J=6.4 Hz, 2H, NHCHCH3),
(g cm−3
)
3
8.62 (t, J=6.4 Hz, 2H, NHCH2). C24H30N4FeO8×0.4
v (Mo–Ka) (mm−1
F(000)
)
5.587
1456
8.741
984
CH2Cl2 (592.3): Anal. Calc. C 49.48, H 5.24, N 9.46;
Found C 49.46, H 5.41, N 9.34.
Crystal size (mm)
2q range (°)
Index ranges
Reflections collected
Independent reflections
Absorption correction
0.20×0.33×0.53
4.82–47.94
−h−k9l
4820
4524 [Rint 0.0266]
Psi-scan
0.20×0.33×0.47
4.50–47.94
+h9k9l
5480
5166 [Rint 0.0158]
Psi-scan
1.0000 and 0.5121
4526/389
1.122
R1/0.0221, wR2/
0.0500
R1/0.0287, wR2/
0.0535
26: 40 mg (0.114 mmol) of 4 and 50 mg (0.232 mmol)
of phenylalanine methyl ester hydrochloric acid salt
were used. After 24 h stirring 26 was obtained as a
slightly yellow powder. m.p.: 89–92°C (red). IR
(CH2Cl2): w˜ =3409 cm−1 m, 3319 m (NH); (KBr): 1745
vs (COOR), 1639 vs (amide I), 1546 vs (amide II), 495
Max. and min. transmission 0.9990 and 0.5752
Data/parameters
Goodness-of-fit on F2
Final R indices [I\2|(I)]
3828/341
1.097
R1/0.0261, wR2/
0.0600
R1/0.0366, wR2/
0.0662
1
m (FeꢀC). H-NMR (400 MHz, CDCl3): l 3.14 (dd,
3J=6.1 Hz, 2J=14.0 Hz, 2H, CHH%Ph), 3.18 (dd,
2
3J=6.1 Hz, J=14.0 Hz, 2H, CHH%Ph), 3.73 (s, 6H,
R indices (all data)
OCH3), 3.78 (dd, 3J=6.3 Hz, 2J=16.3 Hz, 2H,
NHCHH%), 3.88 (dd, 3J=6.3 Hz, 2J=16.3 Hz, 2H,
NHCHH%), 4.39 (m, 2H, Cp-3), 4.44 (m, 2H, Cp-3%),
4.80 (m, 2H, Cp-2), 4.82 (m, 2H, Cp-2%), 4.89 (dt,
Largest diff. peak and hole 0.789 and −0.830
0.698 and −0.786
−3
˚
(e A
)
a One n-butyl group disordered, split.
3
3JH(CH)=6.0 Hz, JH(NH)=7.4 Hz, 2H, NHCHCH2Ph),
7.16 (d, 3J=7.4 Hz, 2H, NHCHCH2Ph), 7.18
(ABB%CC%, 4H, Ph-2,2%), 7.25 (A, 2H, Ph-4), 7.32 (BB%,
3
4H, Ph-3,3%), 8.54 (t, J=6.3 Hz, 2H, NHCH2). 13C-
NMR (100.5 MHz, CDCl3): l 38.05 (CH2Ph), 42.86
(NHCH2), 52.47 (OCH3), 53.81 (NHCH(R)CO), 70.52/
70.76/71.52/71.61 (Cp-2,2%,3,3%), 75.89 (Cp-1), 128.71
(Ph-4), 129.44/135.86 (Ph-2,2%,3,3%), 135.86 (Ph-1),
170.69/171.12/171.81 (COOCH3, 2 · CONH). C36H38-
N4FeO8 (710.6): Anal. Calc. C 60.85, H 5.39, N 7.89;
Found C 60.53, H 5.67, N 7.90.
3H, OCH3), 4.20/4.21 (each s, 5H, Cp), 4.36 (m, 2H,
3
Cp-3,3%), 4.57/4.58 (each dq, JCH=3JNH=7.2 Hz, 1H,
3
NHCHCH3), 4.66 (m, 1H, Cp-2), 4.67 (dq, JH(CH)
=
3JH(NH)=7.4 Hz, 1H, NHCHCH3), 4.71/4.73 (each m,
1H, Cp-2%), 6.22/6.27 (each d br, 3J=7.4 Hz, 1H,
NHCH), 6.72/6.86 (each d br, 3J=7.2 Hz, 1H,
NHCH). C18H22N2FeO4 (386.2): Anal. Calc. C 55.98, H
5.74, N 7.25; Found C 56.26, H 6.01, N 7.34.
6.7. X-ray diffraction analyses [25]
24: 39 mg (0.111 mmol) of 4 and 28 mg (0.223 mmol)
of glycine methyl ester hydrochloric acid salt were used.
Only 5 h stirring were necessary to complete the reac-
tion. After recrystallisation from EtOAc 24 was ob-
tained as a slightly brown powder. m.p.: 173–174°C
(black). IR (KBr): w˜ =3407 cm−1 s br, 3297 s br (NH),
1750 vs (COOR), 1667 vs, 1639 vs (amide I), 1546 vs br
(amide II), 510 w, 493 m (Fe–C). H-NMR (270 MHz,
CDCl3): l 3.76 (s, 6H, OCH3), 3.96 (m, 4H, NHCH2),
4.11 (m, 4H, NHCH2), 4.41 (s br, 4H, Cp-3,3%), 4.82 (s
Data collection: Enraf–Nonius CAD4 Diffractome-
˚
ter, Mo–Ka radiation,
u
0.71073 A, graphite
monochromator, cell constants from 25 centered reflec-
tions, ꢀ-scan (6) or ꢀ–2q-scan (19), intensity of three
standard reflections checked every two hours. Structure
solution by SHELXS-86 and refinement by SHELXL-93
(G.M. Sheldrick, University of Go¨ttingen, Germany)
non-hydrogen atoms refined anisotropically, hydrogens
with U1/1.2×Ueq of the adjacent carbon atom. Full-
1

W. Bauer et al. / Journal of Organometallic Chemistry 579 (1999) 269–279
279
matrix refinement against F2. See Table 2 for crystal
data and structure refinement.
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Acknowledgements
Generous support by Deutsche Forschungsgemein-
schaft, Fonds der Chemischen Industrie and Wacker
Chemie, Mu¨nchen, is gratefully acknowledged. We
would also like to thank Mrs Brigitte Janker and
Professor Dr Herbert Mayr, Mu¨nchen, for cyclic
voltammograms.
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