Preparation of new 'diazo' complexes of manganese stabilised by phosphite ligands

Article abstract of DOI:10.1016/S0022-328X(00)00943-8

A series of mono- and binuclear aryldiazene complexes [Mn(ArN=NH)(CO)_nP_5-n]BPh₄ and [{Mn(CO)_nP_5-n}₂(μ-HN=NAr-ArN=NH)](BPh₄)₂ [P=P(OMe)₃, P(OEt)₃ or P(OPh)₃; Ar=C₆H₅, 4-CH₃C₆H₄; Ar-Ar=4,4′-C₆H₄-C₆H₄, 4,4′-C₆H₄-CH₂-C₆H₄; n=1, 2 or 3] were prepared by allowing hydride species MnH(CO)_nP_5-n to react with the appropriate aryldiazonium salts at -80°C. Characterisation of the complexes by IR and variable-temperature ¹H-, ³¹P-, ¹⁵N-NMR spectra (with ¹⁵N isotopic substitution) are reported. Treatment of aryldiazene derivatives containing both the tricarbonyl Mn(CO)₃P₂ and the dicarbonyl Mn(CO)₂P₃ fragments with NEt₃ affords the pentacoordinate dicarbonyl aryldiazenido Mn(ArN₂)(CO)₂P₂ and [Mn(CO)₂P₂]₂(μ-N₂Ar-ArN₂) derivatives. Instead, the aryldiazene bonded to the monocarbonyl fragment Mn(CO)P₄ is unreactive towards base and does not give aryldiazenido species. Hydrazine complexes [Mn(RNHNH₂)(CO)_nP_5-n]BPh₄ [R=H, CH₃ or C₆H₅; P=P(OMe)₃, P(OEt)₃ or P(OPh)₃; n=1, 2 or 3] were prepared by reacting hydride species MnH(CO)_nP_5-n first with Br?nsted acid (HBF₄ or CF₃SO₃H) and then with an excess of the appropriate hydrazine. The binuclear complex [{Mn(CO)₃[P(OEt)₃]₂}₂(μ-NH₂NH₂)](BPh₄)₂ was also prepared. Oxidation reactions of phenylhydrazine cations [Mn(C₆H₅NHNH₂)(CO)_nP_5-n]⁺ with Pb(OAc)₄ at -40°C give the phenyldiazene [Mn(C₆H₅N=NH)(CO)_nP_5-n]⁺ derivatives, whereas the oxidation of methylhydrazine [Mn(CH₃NHNH₂)(CO)_nP_5-n]⁺ complexes allows the synthesis of the first methyldiazene [Mn(CH₃N=NH)(CO){P(OMe)₃}₄]BPh₄ derivative of manganese.

Full text of DOI:10.1016/S0022-328X(00)00943-8

Journal of Organometallic Chemistry 625 (2001) 217–230
www.elsevier.nl/locate/jorganchem
Preparation of new ‘diazo’ complexes of manganese stabilised by
phosphite ligands
Gabriele Albertin *, Stefano Antoniutti, Emilio Bordignon, Giampaolo Perinello
Dipartimento di Chimica, Uni6ersita` Ca’ Foscari di Venezia, Dorsoduro 2137, I-30123 Venice, Italy
Received 6 October 2000; accepted 14 December 2000
Abstract
series of mono- and binuclear aryldiazene complexes [Mn(ArNꢀNH)(CO)nP5−n]BPh4 and [{Mn(CO)nP5−n}2(m-
A
HNꢀNArꢁArNꢀNH)](BPh4)2 [P=P(OMe)3, P(OEt)3 or P(OPh)3; Ar=C6H5, 4-CH3C6H4; ArꢁAr=4,4%-C6H4ꢁC6H4, 4,4%-
C6H4ꢁCH2ꢁC6H4; n=1, 2 or 3] were prepared by allowing hydride species MnH(CO)nP5−n to react with the appropriate
1
aryldiazonium salts at −80°C. Characterisation of the complexes by IR and variable-temperature H-, 31P-, 15N-NMR spectra
(with 15N isotopic substitution) are reported. Treatment of aryldiazene derivatives containing both the tricarbonyl Mn(CO)3P2 and
the dicarbonyl Mn(CO)2P3 fragments with NEt3 affords the pentacoordinate dicarbonyl aryldiazenido Mn(ArN2)(CO)2P2 and
[Mn(CO)2P2]2(m-N2ArꢁArN2) derivatives. Instead, the aryldiazene bonded to the monocarbonyl fragment Mn(CO)P4 is unreactive
towards base and does not give aryldiazenido species. Hydrazine complexes [Mn(RNHNH2)(CO)nP5−n]BPh4 [R=H, CH3 or
C6H5; P=P(OMe)3, P(OEt)3 or P(OPh)3; n=1, 2 or 3] were prepared by reacting hydride species MnH(CO)nP5−n first with
Brønsted acid (HBF4 or CF3SO3H) and then with an excess of the appropriate hydrazine. The binuclear complex
[{Mn(CO)3[P(OEt)3]2}2(m-NH2NH2)](BPh4)2 was also prepared. Oxidation reactions of phenylhydrazine cations
+
+
[Mn(C6H5NHNH2)(CO)nP5−n
]
with Pb(OAc)4 at −40°C give the phenyldiazene [Mn(C6H5NꢀNH)(CO)nP5−n
]
derivatives,
+
whereas the oxidation of methylhydrazine [Mn(CH3NHNH2)(CO)nP5−n
]
complexes allows the synthesis of the first methyldi-
azene [Mn(CH3NꢀNH)(CO){P(OMe)3}4]BPh4 derivative of manganese. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Manganese; Diazene; Diazenido; Hydrazine; Dinuclear compounds
the ‘diazo’ ligands. However, the influence of the vari-
ous factors on the properties of these complexes has not
still been completely rationalised and much remains
unknown about the chemistry of coordinate ‘diazo’
molecules.
1. Introduction
The chemistry of diazenido, RN2, diazene, RNꢀNH,
and hydrazine, RNHNH2, complexes of transition
metals has been studied extensively [1–3] in the past 25
years, not only for their relevance in the nitrogen
fixation process, but also for the interesting chemical
and structural properties that these classes of com-
pounds may exhibit and the potential reactions involv-
ing the NN single and multiple bond.
Numerous complexes of various metals have been
prepared [1–3] and much work has been addressed to
study the structure and reactivity of these important
classes of compounds, in an attempt to determine the
influence of the central metal, its oxidation state and
the nature of the ancillary ligand on the properties of
We are active in this field and have reported exten-
sively on the synthesis and reactivity of ‘diazo’ com-
plexes of the iron family [4]. Recently, we have also
begun study on the Mn triad and reported [5] the
synthesis and some reactions of aryldiazene, aryldi-
azenido and hydrazine complexes of manganese, which
are stabilised by the Mn(CO)3P2 fragment containing
phosphonite, PPh(OEt)2, and phosphinite, PPh2OEt lig-
ands. In order to determine the influence of the phos-
phine ligand on the properties of ‘diazo’ complexes of
manganese, the chemistry of which is rather restricted
[6], we extended these studies to include phosphite
P(OR)3 (R=Me, Et or Ph) as ancillary ligands. The
results of these studies are reported here.
* Corresponding author. Fax: +39-041-2578517.
E-mail address: albertin@unive.it (G. Albertin).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00943-8

218
G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
2. Experimental
P(OMe)3 (11.2 cm3, 90 mmol) and the mixture was
irradiated for 20 h at room temperature (r.t.) in a Pyrex
Schlenk flask, using a standard 400 W, medium-pres-
sure mercury arc lamp. The solvent was removed under
reduced pressure, giving an oil which was treated with
5 cm3 of ethanol. By slow cooling to −25°C of the
resulting solution, a white solid separated out, which
was filtered and dried under vacuum; yield ]60%. It
may be noted that a shorter irradiation time (8–12 h)
gives a mixture of MnH(CO)[P(OMe)3]4 and Mn-
H(CO)2[P(OMe)3]3, from which we were not able to
separate the dicarbonyl, owing its decomposition dur-
ing attempts at chromatographic separation.
Anal. Calc. for C13H37MnO13P4: C, 26.9; H, 6.4.
Found: C, 26.8; H, 6.6%. lH(CD2Cl2, 298 K) 3.56 (36
H, br, CH3), −8.72 (1 H, qi, hydride, JPH=50 Hz);
lP(CD2Cl2, 298 K) 199.7 (s). IR, cm−1 (KBr) 1866 (s)
w(CO).
2.1. General considerations and physical measurements
All synthetic work was carried out under an inert
atmosphere using standard Schlenk techniques or a
Vacuum Atmosphere dry-box. Once isolated, the com-
plexes were found to be relatively stable in air, but were
stored under an inert atmosphere at −25°C. All sol-
vents were dried over appropriate drying agents, de-
gassed on a vacuum line and distilled into vacuum-tight
storage flasks. Phosphites P(OMe)3 and P(OEt)3
(Aldrich) were purified by distillation under nitrogen;
P(OPh)3 was used as received. Diazonium salts were
obtained in the usual way [7]. Related di-diazonium
[N2ArꢁArN2](BF4)2 (ArꢁAr=4,4%-C6H4ꢁC6H4; 4,4%-
C6H4ꢁCH2ꢁC6H4) salts were prepared by treating
amine precursors H2NArꢁArNH2 with NaNO2, as de-
scribed in the literature for common mono-diazonium
salts [7]. Labelled diazonium tetrafluoroborate
2.2.2. MnH(CO)2[P(OPh)3]3
[C6H5Nꢂ15N]BF4
and
[4,4%-15NꢂNC6H4ꢁC6H4-
An excess of P(OPh)3 (22 cm3, 70 mmol) was added
to a solution of MnH(CO)5 (2.55 g, 13 mmol) in 50 cm3
of toluene and the solution was irradiated with a stan-
dard 400 W, medium-pressure mercury arc lamp for 48
h. The solvent was removed under reduced pressure
and the resulting oil chromatographed on a silica gel
column (length 60 cm, diameter 4 cm) using as eluent a
mixture of petroleum ether (40–70°C) and benzene in a
10:1 ratio. The first eluate (ꢀ650 cm3) allowed us to
separate the tricarbonyl MnH(CO)3[P(OPh)3]2 (yield ]
30%); from the second eluate (650 cm3), after evapora-
tion of the solvent and treatment with 3 cm3 of ethanol
Nꢂ15N](BF4)2 were prepared from Na15NO2 (99% en-
riched, CIL) and the appropriate amine. Hydrazines
CH3NHNH2 and C6H5NHNH2 were Aldrich products
used as received. Hydrazine NH2NH2 was prepared by
decomposition of hydrazine cyanurate (Fluka) follow-
ing the reported method [8]. Mn2(CO)10 (Aldrich),
HBF4·Et2O (54% solution) and triflic acid (Aldrich)
were used as purchased. Triethylamine was dried with
CaH2 and distilled before use. Other reagents were
purchased from commercial sources in the highest
available purity and used as received. Infrared spectra
were recorded on a Nicolet Magna 750 FTIR spec-
trophotometer. NMR spectra (1H, 13C, 31P, 15N) were
obtained on a Bruker AC200 spectrometer at tempera-
tures varying between −90 and +30°C, unless other-
of the resulting oil,
a
white solid of Mn-
H(CO)2[P(OPh)3]3 separated out, which was filtered and
dried under vacuum; yield ]35%
Anal. Calc. for C56H46MnO11P3: C, 64.5; H, 4.5.
Found: C, 64.7; H, 4.4%. lH(C6D6, 298 K) 7.40–6.50
(45 H, m, Ph), A2BX spin system, lX −7.89 (X=hy-
dride), JAX=50, JBX=70 Hz; lP(C6D6, 298 K) A2B
spin system, lA 178.5, lB 171.3, JAB=102 Hz. IR,
cm−1 (KBr) 1978 (s), 1920 (s) w(CO).
2.2.3. MnH(CO)3P2 [P=P(OMe)3 or P(OPh)3]
An excess of the appropriate phosphite (39 mmol)
was added to a solution of MnH(CO)5 (2.55 g, 13
mmol) in 30 cm3 of toluene and the reaction mixture
was refluxed for 90 min. The solvent was removed
under reduced pressure and the oil obtained was tritu-
rated with 10 cm3 of ethanol. By cooling to −25°C of
the resulting solution, white microcrystals of the
product separated out, which were collected and dried
under vacuum; yield ]70%
1
wise noted. H and 13C spectra are referred to internal
tetramethylsilane; 31P{1H} chemical shifts are reported
with respect to 85% H3PO4, with downfield shifts con-
sidered positive. 15N spectra refer to external CH315NO2,
with downfield shifts considered positive. The SWAN-MR
software package [9] was used to treat NMR data. The
conductivities of 10−3 mol dm−3 solutions of the com-
plexes in CH3NO2 at 25°C were measured with a Ra-
diometer CDM 83 instrument.
2.2. Synthesis of complexes
The pentacarbonyl species MnH(CO)5 [10a] and the
hydrides MnH(CO)3[P(OEt)3]2, MnH(CO)2[P(OEt)3]3
and MnH(CO)[P(OEt)3]4 [10b] were prepared according
to the procedures previously reported.
Anal. Calc. for C9H19MnO9P2 (MnH(CO)3[P-
(OMe)3]2): C, 27.9; H, 4.9. Found: C, 27.7; H, 5.0%.
lH(C6D6, 298 K) 3.42 (18 H, t, CH3), −8.16 (1 H, t,
hydride, JPH=44 Hz); lP(C6D6, 298 K) 194.0 (s, br).
IR, cm−1 (KBr) 2023 (m), 1940 (s), 1925 (s) w(CO).
2.2.1. MnH(CO)[P(OMe)3]4
A solution of MnH(CO)5 (2.55 g, 13 mmol) in 50 cm3
of toluene was treated, under argon, with an excess of

G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
219
Anal. Calc. for C39H31MnO9P2 (MnH(CO)3[P-
2.2.7. [Mn(C6H5Nꢀ15NH)(CO){P(OEt)3}4]BPh4 (1b1),
(OPh)3]2): C, 61.6; H, 4.1. Found: C, 61.7; H, 4.2%.
lH(C6D6, 298 K) 7.30–6.80 (30 H, m, Ph), −8.09 (1 H,
t, hydride, JPH=50 Hz); lP(C6D6, 298 K) 183.6 (s). IR,
cm−1 (KBr) 2075 (m), 1980 (s), 1956 (s) w(CO).
[Mn(C6H5Nꢀ15NH)ꢁ(CO)2{P(OEt)3}3]BPh4 (2b1),
[Mn(C6H5Nꢀ15NH)(CO)3{P(OEt)3}2]BPh4 (3b1)
These complexes were prepared like related com-
plexes 1b, 2b and 3b using the labelled
(C6H5Nꢂ15N)BF4 aryldiazonium salt; yield ]80%.
2.2.4. [Mn(C6H5NꢀNH)(CO)P4]BPh4 (1),
2.2.8. [{Mn(CO)P4}2(v-4,4%-HNꢀNC6H4ꢁC6H4Nꢀ
NH)](BPh4)2 (4), [{Mn(CO)2P3}2(v-4,4%-HNꢀ
NC6H4ꢁC6H4NꢀNH)](BPh4)2 (5) or [{Mn(CO)3P2}2-
(v-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)](BPh4)2 (6)
[P=P(OMe)3 (a), P(OEt)3 (b) or P(OPh)3 (c)]
Solid samples of the appropriate hydrides (1 mmol)
[Mn(C6H5NꢀNH)(CO)2P3]BPh4 (2),
[Mn(C6H5NꢀNH)(CO)3P2]BPh4 (3) [P=P(OMe)3 (a),
P(OEt)3 (b) or P(OPh)3 (c)]
In a 25 cm3 three-necked round-bottomed flask were
placed a solid sample of the appropriate hydride Mn-
H(CO)nP5−n (n=1, 2, 3) (1 mmol) and solid
[C6H5N2]BF4 (0.192 g, 1 mmol) and the flask cooled to
−196°C. Dichloromethane (10 cm3) was added and the
reaction mixture, brought to r.t., was stirred for 2 h.
The solvent was removed under reduced pressure, giv-
ing an oil which was treated with ethanol (3 cm3). The
addition of an excess of NaBPh4 (0.68 g, 2 mmol) in 2
cm3 of ethanol to the resulting solution caused the
separation of a yellow solid, the precipitation of which
was completed by cooling to −25°C of the reaction
mixture. The solid was filtered and crystallised from
and
of
the
bis(aryldiazonium)
salt
(4,4%-
N2C6H4ꢁC6H4N2)(BF4)2 (0.191 g, 0.5 mmol) were
placed in a 25 cm3 three-necked round-bottomed flask
and cooled to −196°C. Acetone (10 cm3) or a mixture
(CH3)2CO:CH2Cl2 in ratio 1:1 (10 cm3) was slowly
added and the resulting solution brought to r.t. and
stirred for 4 h. The solvent was removed under reduced
pressure, giving an oil which was treated with ethanol
(2 cm3). The addition of an excess of NaBPh4 (0.68 g, 2
mmol) to the resulting solution caused, after cooling to
−25°C, the separation of a yellow solid which was
filtered and crystallised from CH2Cl2 and ethanol; yield
]85%; \M/S cm2 mol−1=114.2 for 4a, 119.7 for 4b,
123.1 for 5b, 122.5 for 5c, 99.6 for 6a, 107.4 for 6b.
Anal. Calc. for C86H122B2Mn2N4O26P8 (4a): C, 51.5;
H, 6.1; N, 2.8. Found: C, 51.3; H, 6.2; N, 2.7%.
Anal. Calc. for C110H170B2Mn2N4O26P8 (4b): C, 56.4;
H, 7.3; N, 2.4. Found: C, 56.2; H, 7.3; N, 2.3%.
Anal. Calc. for C100H140B2Mn2N4O22P6 (5b): C, 58.1;
H, 6.8; N, 2.7. Found: C, 58.2; H, 6.7; N, 2.6%.
Anal. Calc. for C172H140B2Mn2N4O22P6 (5c): C, 70.5;
H, 4.8; N, 1.9. Found: C, 70.3; H, 4.7; N, 1.8%.
Anal. Calc. for C78H86B2Mn2N4O18P4 (6a): C, 57.7;
H, 5.3; N, 3.5. Found: C, 57.6; H, 5.4; N, 3.6%.
Anal. Calc. for C90H110B2Mn2N4O18P4 (6b): C, 60.4;
H, 6.2; N, 3.1 Found: C, 60.6; H, 6.0; N, 3.0%.
CH2Cl2 and ethanol; yield ]80%; \M/S cm2 mol−1
52.7 for 1a, 55.0 for 1b, 49.6 for 2b, 51.3 for 2c, 50.8 for
3a, 58.8 for 3b.
=
Anal. Calc. for C43H62BMnN2O13P4 (1a): C, 51.4; H,
6.2; N, 2.8. Found: C, 51.2; H, 6.2; N, 2.7%.
Anal. Calc. for C55H86BMnN2O13P4 (1b): C, 56.2; H,
7.4; N, 2.4. Found: C, 56.2; H, 7.5; N, 2.5%.
Anal. Calc. for C50H71BMnN2O11P3 (2b): C, 58.0; H,
6.9; N, 2.7. Found: C, 58.2; H, 6.8; N, 2.6%.
Anal. Calc. for C86H71BMnN2O11P3 (2c): C, 70.4; H,
4.9; N, 1.9. Found: C, 70.2; H, 4.8; N, 1.9%.
Anal. Calc. for C39H44BMnN2O9P2 (3a): C, 57.7; H,
5.5; N, 3.5. Found: C, 57.8; H, 5.4; N, 3.4%.
Anal. Calc. for C45H56BMnN2O9P2 (3b): C, 60.3; H,
6.3; N, 3.1. Found: C, 60.2; H, 6.5; N, 3.0%.
2.2.5. [Mn(C6H5NꢀNH)(CO)3{P(OPh)3}2]BF4 (3c)
This complex was prepared exactly like related com-
pounds 1–3, but was separated as BF4 salt; yield ]
65%; \M/S2 cm2 mol−1=90.4.
Anal. Calc. for C45H36BF4MnN2O9P2: C, 56.8; H,
3.8; N, 2.9. Found: C, 56.6; H, 3.9; N, 2.9%.
2.2.9. [{Mn(CO)[P(OEt)3]4}2(v-4,4%-HNꢀ
NC6H4ꢁCH2ꢁC6H4NꢀNH)](BPh4)2 (4*b)
This complex was prepared exactly like related com-
pound 4b using the bis(aryldiazonium) salt (4,4%-
N2C6H4ꢁCH2ꢁC6H4N2)(BF4)2 as reagent; yield ]80%;
\M/S cm2 mol−1=113.7.
Anal. Calc. for C112H174B2Mn2N4O26P8: C, 56.7; H,
7.4; N, 2.4. Found: C, 56.6; H, 7.5; N, 2.3%.
2.2.6. [Mn(4-CH3C6H4NꢀNH)(CO){P(OEt)3}4]BPh4
(1*b)
This complex was prepared exactly like related
phenyldiazene compound 1b; yield ]80%; \M/S cm2
mol−1=57.1.
2.2.10. [{Mn(CO)[P(OEt)3]4}2(v-4,4%-H15NꢀNC6H4ꢁ
C6H4Nꢀ15NH)](BPh4)2 (4b1)
This compound was prepared exactly like related 4b
using the labelled (4,4%-15NꢂNC6H4ꢁC6H4Nꢂ15N)(BF4)2
aryldiazonium salt; yield ]85%.
Anal. Calc. for C56H88BMnN2O13P4: C, 56.7; H, 7.5;
N, 2.4. Found: C, 56.5; H, 7.3; N, 2.3%.

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G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
2.2.11. Mn(C6H5N2)(CO)2[P(OPh)3]2 (7c),
[Mn(CO)2P2]2(v-4,4%-N2C6H4ꢁC6H4N2) (8)
[P=P(OMe)3 (a), P(OEt)3 (b) or P(OPh)3 (c)]
An excess of triethylamine (0.69 cm3, 5 mmol) was
added to a solution of the appropriate aryldiazene
Anal. Calc. for C49H84BMnN2O13P4 (9b): C, 53.6; H,
7.7; N, 2.6. Found: C, 53.8; H, 7.6; N, 2.5%.
Anal. Calc. for C44H69BMnN2O11P3 (10b): C, 55.0;
H, 7.2; N, 2.9. Found: C, 54.9; H, 7.2; N, 3.0%.
Anal. Calc. for C33H42BMnN2O9P2 (11a): C, 53.7; H,
5.7; N, 3.8. Found: C, 53.6; H, 5.7; N, 3.7%.
Anal. Calc. for C39H54BMnN2O9P2 (11b): C, 57.0; H,
6.6; N, 3.4. Found: C, 56.8; H, 6.5; N, 3.5%.
complex
[Mn(C6H5NꢀNH)(CO)3P2]BPh4
or
[{Mn(CO)3P2}2(m - 4,4% - HNꢀNC6H4ꢁC6H4NꢀNH)]
(BPh4)2 (1 mmol) in 10 cm3 of CH2Cl2 and the reaction
mixture stirred for about 2 h. The solvent was removed
under reduced pressure, giving an oil which was tritu-
rated with benzene (5 cm3).
A
white solid of
2.2.14. [Mn(CH3NHNH2)(CO)P4]BPh4 (12),
[Mn(CH3NHNH2)(CO)2P3]BPh4 (13b) [P=P(OMe)3
(a) or P(OEt)3 (b)]
(NHEt3)BPh4 slowly separated out from the resulting
solution, which was collected by filtration and rejected.
The solution was evaporated to dryness, giving a red-
dish–brown oil which was treated with 2 cm3 of etha-
nol. By cooling of the resulting solution to −25°C,
orange microcrystals of the product were obtained,
which were filtered and dried under vacuum; yield
]75%.
Anal. Calc. for C44H35MnN2O8P2 (7c): C, 63.2; H,
4.2; N, 3.4. Found: C, 63.0; H, 4.1; N, 3.5%.
Anal. Calc. for C28H44Mn2N4O16P4 (8a): C, 36.3; H,
4.8; N, 6.1. Found: C, 36.4; H, 4.7; N, 6.0%.
Anal. Calc. for C40H68Mn2N4O16P4 (8b): C, 43.9; H,
6.3; N, 5.1. Found: C, 43.7; H, 6.3; N, 5.3%.
Anal. Calc. for C88H68Mn2N4O16P4 (8c): C, 63.2; H,
4.1; N, 3.4. Found: C, 63.1; H, 4.2; N, 3.3%.
A
solution of the appropriate hydride Mn-
H(CO)nP5−n (n=1, 2) (0.83 mmol) in 10 cm3 of
CH2Cl2 was cooled to −196°C and treated with an
equimolar amount of HBF4·Et2O (119 ml of a 54%
solution in Et2O, 0.83 mmol). The reaction mixture was
brought to r.t., stirred for 1 h and again cooled to
−196°C. An excess of CH3NHNH2 (133 mL, 2.5 mmol)
was then added, and the reaction mixture brought to
r.t. and stirred for about 20 h. The solvent was removed
under reduced pressure, giving an oil which was treated
with ethanol (5 cm3) containing an excess of NaBPh4
(0.68 g, 2 mmol). A pale yellow solid separated out
from the resulting solution, which was filtered and
crystallised from CH2Cl2 and ethanol; yield ]60%;
\M/S cm2 mol−1=60.2 for 12a, 58.5 for 12b, 56.8 for
13b.
2.2.12. Mn(C6H5Nꢂ15N)(CO)2[P(OPh)3]2 (7c1)
This compound was prepared exactly like related 7c
Anal. Calc. for C38H62BMnN2O13P4 (12a): C, 48.3;
H, 6.6; N, 3.0. Found: C, 48.5; H, 6.5; N, 3.1%.
Anal. Calc. for C50H86BMnN2O13P4 (12b): C, 54.0;
H, 7.8; N, 2.5. Found: C, 54.2; H, 7.7; N, 2.4%.
Anal. Calc. for C45H71BMnN2O11P3 (13b): C, 55.5;
H, 7.3; N, 2.9. Found: C, 55.3; H, 7.2; N, 3.0%.
by
treatment
of
the
labelled
compound
[Mn(C6H5Nꢀ15NH)(CO)3{P(OPh)3}2]BPh4 with NEt3;
yield ]75%.
2.2.13. [Mn(NH2NH2)(CO)P4]BPh4 (9),
[Mn(NH2NH2)(CO)2P3]BPh4 (10b),
[Mn(NH2NH2)(CO)3P2]BPh4 (11) [P=P(OMe)3 (a) or
P(OEt)3 (b)]
2.2.15. [Mn(C6H5NHNH2)(CO)P4]BPh4 (14),
[Mn(C6H5NHNH2)(CO)3P2]BPh4 (15a) [P=P(OMe)3
(a) or P(OEt)3 (b)]
These complexes were prepared following the method
used for the related NH2NH2 and CH3NHNH2 deriva-
tives 9–13: the appropriate hydride (0.83 mmol), in 10
cm3 of CH2Cl2, was treated first with an equimolar
amount of HBF4·Et2O (14a) or CF3SO3H (14b and 15a)
and then with a slight excess (91 ml, 0.92 mmol) of
C6H5NHNH2. The compounds were crystallised from
To a solution of the appropriate hydride Mn-
H(CO)nP5−n (n=1, 2, 3) (0.83 mmol), in 10 cm3 of
CH2Cl2 cooled to −196°C, an equimolar amount of
HBF4·Et2O (119 ml of a 54%° solution in Et2O, 0.83
mmol) was added and the reaction mixture, brought to
r.t., was stirred for 1 h. The solution was again cooled
to −196°C, treated with a slight excess of NH2NH2
(28.9 ml, 0.92 mmol), and then brought to r.t. After 3 h
of stirring, the solvent was removed under reduced
pressure, giving an oil which was triturated with etha-
nol (3 cm3). The addition of an excess of NaBPh4 (0.68
g, 2 mmol) caused the separation of a pale yellow solid
which was filtered and crystallised from CH2Cl2 and
ethanol; yield ]55%; \M/S cm2 mol−1=50.3 for 9a,
55.9 for 9b, 58.0 for 10b, 54.8 for 11a, 58.3 for 11b.
Anal. Calc. for C37H60BMnN2O13P4 (9a): C, 47.8; H,
6.5; N, 3.0. Found: C, 47.6; H, 6.6; N, 2.9%.
CH2Cl2 and ethanol; yield ]65%; \M/S cm2 mol−1
54.4 for 14a, 59.0 for 14b, 57.6 for 15a.
Anal. Calc. for C43H64BMnN2O13P4 (14a): C, 51.3; H,
6.4; N, 2.8. Found: C, 51.5; H, 6.3; N, 2.9%.
Anal. Calc. for C55H88BMnN2O13P4 (14b): C, 56.2; H,
7.6; N, 2.4. Found: C, 56.0; H, 7.5; N, 2.5%.
Anal. Calc. for C39H46BMnN2O9P2 (15a): C, 57.5; H,
5.7; N, 3.4. Found: C, 57.2; H, 5.8; N, 3.4%.
=

G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
221
2.2.16. [{Mn(CO)3[P(OEt)3]2}2(v-NH2NH2)](BPh4)2
(16b)
2.2.17. [Mn(CH3NꢀNH)(CO){P(OMe)3}4]BPh4 (17a)
A sample of [Mn(CH3NHNH2)(CO){P(OMe)3}4]-
BPh4 (12a) (0.472 g, 0.5 mmol) was placed in a three-
necked 25 cm3 round-bottomed flask fitted with a solid-
addition sidearm containing an equimolar amount of
Pb(OAc)4 (0.222 g, 0.5 mmol). Dichloromethane (10
cm3) was added, the solution cooled to −40°C, and
Pb(OAc)4 added portionwise over 20–30 min to the
cold stirred solution. The reaction mixture was then
brought to r.t. and filtered, and the solvent was re-
moved under reduced pressure, giving an oil. The addi-
tion of ethanol containing an excess of NaBPh4 (0.34 g,
1 mmol) caused the separation of a yellow–orange
solid which was filtered and crystallised from CH2Cl2
and ethanol; yield ]70%; \M/S cm2 mol−1=56.2.
Anal. Calc. for C38H60BMnN2O13P4: C, 48.4; H, 6.4;
N, 3.0. Found: C, 48.6; H, 6.3; N, 3.1%.
To a solution of MnH(CO)3[P(OEt)3]2 (0.39 g, 0.83
mmol) in 10 cm3 of CH2Cl2 cooled to −196°C was
added an equimolar amount of HBF4·Et2O (119 ml of a
54%° solution in Et2O, 0.83 mmol). The reaction mix-
ture was brought to r.t., stirred for 90 min and then
again cooled to −196°C. Hydrazine (13.0 ml, 0.415
mmol) was added, and the solution, brought to r.t., was
stirred (at this temperature) for 24 h. The solvent was
removed under reduced pressure, giving an oil which
was treated with ethanol (3 cm3) containing an excess
of NaBPh4 (0.68 g, 2 mmol). By slow cooling of the
resulting solution to −25°C, white microcrystals sepa-
rated out, which were filtered and dried under vacuum;
yield ]55%; \M/S cm2 mol−1=118.6.
Anal. Calc. for C78H104B2Mn2N2O18P4: C, 58.1; H,
6.5; N, 1.7. Found: C, 57.9; H, 6.7; N, 1.6%.
3. Results and discussion
3.1. Aryldiazene and aryldiazenido deri6ati6es
All the hydride complexes MnH(CO)nP5−n,where
n=1, 2 or 3, react with both mono and bis(aryldiazo-
nium) cations to give mono [Mn(ArNꢀNH)(CO)n-
+
P5−n
]
(1–3) and binuclear [{Mn(CO)nP5−n}2(m-HNꢀ
NArꢁArNꢀNH)]2+ (4–6) derivatives, which were iso-
lated as BPh−4 salts and characterised (Schemes 1 and
2).
An exact stoichiometric ratio between the reagents
and the start of the reaction at low temperature seems
to be crucial for successful synthesis of the aryldiazene
derivatives. Otherwise, some decomposition products or
oily substances are found in the final reaction products.
The formation of stable aryldiazene species for all
Scheme 1. P=P(OMe)3 (a), P(OEt)3 (b) or P(OPh)3 (c); Ar=C6H5 or
4-CH3C6H4.
carbonyl:phosphite ratios of [Mn(ArNꢀNH)(CO)n-
+
P5−n
]
is rather surprising, because with substituted
phosphites of the type PPh(OEt)2 or PPh2OEt only the
tricarbonyl fragment Mn(CO)3P2 has been reported [5]
to stabilise aryldiazene [Mn(ArNꢀNH)(CO)3P2]+
derivatives. The use of P(OR)3 phosphite as ancillary
ligand allows stable aryldiazene species to be obtained
for every CO:P ratio, and shows the important influ-
ence of the phosphine ligand in the synthesis of ‘diazo’
complexes. The P(OR)3 groups are in fact good p-ac-
ceptor ligands, certainly better than PPh(OR)2 or
PPh2(OR) ones [11], and this probably allows the sub-
stitution of CO with phosphite in the Mn(CO)5 group
without extensively altering the electronic properties of
the manganese fragment Mn(CO)nP5−n, so that the
related aryldiazene complexes 1–4 are stable with all
the CO:P ratios of the Mn(CO)nP5−n group.
Aryldiazene complexes 1–6 are orange or red solids,
stable in air and in solution of polar organic solvents,
in which they behave as 1:1 (1–3) or 2:1 (4–6) elec-
Scheme 2. P=P(OMe)3 (a), P(OEt)3 (b) or P(OPh)3 (c); ArꢁAr=4,4%-
C6H4ꢁC6H4 or 4,4%-C6H4ꢁCH2ꢁC6H4.

222
G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
trolytes [12]. Analytical and spectroscopic data (IR and
NMR, Tables 1 and 2) support the proposed formula-
tion and also allow a geometry in solution of the type
reported in Schemes 1 and 2 to be established.
The H-NMR spectra are consistent with the pres-
ence of the diazene ligand, showing the characteristic,
slightly broad NH signal in the high frequency region at
The chemical properties of aryldiazene complexes
1–6 were studied and the results are summarised in
Scheme 3.
Both mono and binuclear tricarbonyl complexes 3
and 6 quickly react with triethylamine to give pentaco-
ordinate aryldiazenido Mn(ArN2)(CO)2P2 (7) and
[Mn(CO)2P2]2(m-N2ArꢁArN2) (8) derivatives in almost
quantitative yield (]90%); they were isolated in the
solid state and characterised. Evolution of CO was
observed during the reaction course, which also pro-
ceeds with the formation of the ammonium cation
[NHEt3]+. Its separation as BPh4 salt in an equivalent
amount supports the stoichiometry reported in Scheme
3 (Eqs. (1) and (2)).
Surprisingly, treatment of dicarbonyl complexes 2
and 5 with NEt3 changes the colour of the solution,
with the formation of the same aryldiazenido complexes
7 and 8 obtained starting from tricarbonyls 3 and 6.
Free phosphite was liberated during the reaction course,
in agreement with the stoichiometry reported in Scheme
3 (Eqs. (3) and (4)).
1
14.82–14.14
ppm.
In
the
related
labelled
[Mn(C6H5Nꢀ15NH)(CO)n{P(OEt)3}5−n]BPh4 1b1, 2b1,
3b1 and [{Mn(CO)[P(OEt)3]4}2(m-4,4%-H15NꢀNC6H4ꢁ
C6H4Nꢀ15NH)](BPh4)2 4b1 complexes, this broad signal
1
is split into a doublet of multiplets with J15 of 62 or
NH
65 Hz, in agreement with the proposed formulation.
Proton-coupled 15N-NMR spectra (Table 2) also sup-
port the presence of the diazene ligand, showing a
doublet of multiplets between 43.6 and 22.6 ppm for the
resonances of the labelled derivatives.
At room temperature, the 31P{1H}-NMR spectra of
monocarbonyl complexes 1 and 4 show a slightly broad
signal which resolves into a sharp singlet at −90°C,
indicating the presence of four equivalent phosphite
ligands. The IR spectra only show one w(CO) band, and
a mutually trans position of the diazene and CO ligands
may therefore be proposed for these derivatives.
The presence of a broad 31P{1H} signal at room
temperature for 1 and 4 indicates a fluxional process,
which may involve the aryldiazene ligand or a simple
interchange of the positions of the phosphine groups.
Instead, monocarbonyls [Mn(ArNꢀNH)(CO)P4]+ (1)
and the related binuclear derivatives 4 do not react with
neither NEt3 nor stronger bases (NaOC2H5), and the
starting diazene complexes can be recovered unchanged
after 24 h of reaction in the presence of an excess of
base (Scheme 3, Eqs. (5) and (6)).
Aryldiazenido complexes 7 and 8 are orange solids
stable in air and in solution of organic solvents, where
they behave as non-electrolytes. The infrared spectra of
both mono- and binuclear compounds show two strong
bands in the w(CO) region, indicating that the two
carbonyls are in a mutually cis position. The spectra
also have two medium-intensity bands at 1650–1561
cm−1, which are both shifted at a lower frequency in
the corresponding labelled 7c1 and may be attributed to
the w(N2) of the aryldiazenido ligand. The presence of
two or more w(N2) bands for complexes containing only
one ArN2 group is not surprising, having already been
observed in several derivatives [1,5]. It has been re-
ported [13] that these bands result from resonance
interaction of w(NꢂN) with the weak vibrational mode
of the attached phenyl group, and this probably also
applies to our derivatives. The values of the impertur-
bated w%(N2) were also calculated and fall in the range
1618–1591 cm−1, suggesting, by comparison with other
aryldiazenido complexes [5,14–16], a singly-bent aryldi-
azenido ligand.
1
Since the H-NMR spectra of 15N-labelled 1b1 and 4b1
are sharp between +30 and −90°C, a fluxional pro-
cess related to the aryldiazene ligand may be excluded.
Therefore, it is plausible to assume that this fluxional
process simply results in the interchange of the position
of the P ligands at room temperature and, as tempera-
ture is lowered, this change is slowed giving, at −90°C,
a static structure with four equivalent phophorus nuclei.
The infrared spectra of dicarbonyl complexes 2 and 5
show two strong w(CO) bands, in agreement with the
presence of two carbonyls in a mutually cis position.
These two CO ligands are magnetically inequivalent, as
shown by the 13C{1H}-NMR spectra of 5b, which
display two well-separated multiplets at 222.4 and 217.5
ppm, attributed to two inequivalent carbonyl carbon
atoms. Furthermore, the 31P{1H}-NMR spectra of 2
and 5 appear as A2B multiplets, suggesting a mer–cis
geometry for the dicarbonyl derivatives.
The IR spectra of complexes 3 and 6 containing the
tricarbonyl fragment Mn(CO)3P2 show three w(CO)
bands (one medium, and two of strong intensity) indi-
cating a mer arrangement of the three carbonyl ligands.
At room temperature, the 31P{1H}-NMR spectra ap-
pear as a broad signal, which resolves into a sharp
singlet at −90°C, in agreement with the presence of
two magnetically equivalent phosphite ligands. On this
basis, a mer–trans geometry can be proposed in solu-
tion for tricarbonyl aryldiazene complexes 3 and 6.
The 15N-NMR spectra also fit the presence of a singly
bent ArN2 ligand [17], showing a broad triplet at 62.8
ppm, due to the coupling with two magnetically equiva-
lent phosphorus nuclei for the [Mn(C6H5Nꢂ15N)-
(CO)2[P(OEt)3]2 derivative.
In the temperature range between +30 and −90°C
the 31P{1H}-NMR spectra of aryldiazenido complexes 7
and 8 consist of a sharp singlet, indicating the magnetic

G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
223
equivalence of the two phosphorus nuclei. On the basis
of these data, we cannot distinguish between the two
geometries I and II reported in Scheme 4.
through protonation of the N1 nitrogen atom of the
aryldiazenido group. The unreactivity of our
Mn(ArN2)(CO)2P2 species towards acids may be at-
tributed to the properties of phosphites P(OR)3, which
are better p-acceptor ligands [11] than PPh(OEt)2 or
PPh2OEt, and probably make the ArN2 group less
reactive toward protonation. In fact, the reaction with
Brønsted acid of a singly-bent aryldiazenido complex
giving an aryldiazene should result in a two e− oxida-
tion of the central metal [4a,5], from Mn(−1) to
Mn(+1), and the presence in Mn(ArN2)(CO)2P2 7, 8
derivatives of four good p-acceptor ligands [two CO
and two P(OR)3] may make oxidation rather difficult,
as complexes 7, 8 are unreactive towards acids. Also in
this case, therefore, the nature of the ancillary ligands
seems to play an important role in determining the
properties of the ‘diazo’ derivatives.
However, taking into account the fact that previously
reported X-ray structures of pentacoordinate aryldi-
azenido complexes [15,16] contain the singly-bent
ArN+2 ligand in the equatorial position of a trigonal
bipyramidal geometry, we tentatively propose structure
I for our derivatives 7 and 8.
The presence of a singly-bent ArN+2 group in
Mn(ArN2)(CO)2P2 complexes containing
a formal
Mn(−1) central metal suggests [4e,5,16b] that deproto-
nation of the aryldiazene ArNꢀNH in precursors 1–6 is
followed by rearrangement of the ArN−2 ligand to
ArN+2 , with formal two e− reduction of the central
metal to Mn(−1). The concurrent dissociation of one
ligand gives the final pentacoordinate 18-electron com-
plexes (Scheme 5).
The formation exclusively of dicarbonyl aryldi-
azenido Mn(ArN2)(CO)2P2 derivatives by deprotona-
tion of both tricarbonyl [Mn(ArNꢀNH)(CO)3P2]+ and
dicarbonyl [Mn(ArNꢀNH)(CO)2P3]+ precursors indi-
cates that the final product does determine the nature
of the ligand liberated in the reaction course. In other
words, the dissociation of one carbonyl in one case and
one phosphite in the other is dictated by the need to
reach the most stable stoichiometry in the final
Mn(ArN2)(CO)2P2 derivative. Aryldiazenido com-
pounds not containing the dicarbonyl fragment
Mn(CO)2P2 are probably not stable and cannot be
isolated.
The instability of aryldiazenido complexes with a
CO:P ratio different from 2:2 may also explain the
unreactivity toward base of both monocarbonyls
[Mn(ArNꢀNH)(CO)P4]+ (1) and [{Mn(CO)P4}2(m-
HNꢀNArꢁArNꢀNH)]2+ (3). Deprotonation and con-
current dissociation of one ligand (CO or P) should
give aryldiazenido species containing MnP4 or
Mn(CO)P3 fragments, the probable instability of which
prevents the deprotonation reaction. However, the un-
reactivity toward base of aryldiazene monocarbonyl
complexes 1 and 3 may also be due to other factors,
such as reluctance to dissociate a ligand or low acidity
of the diazene proton, although the stability of final
aryldiazenido complexes and/or their stoichiometry
cannot be underestimated in determining the total reac-
tion course.
3.2. Hydrazine complexes
A series of hydrazine complexes [Mn(RNHNH2)-
(CO)nP5−n]BPh4 (9–15) were prepared by reacting hy-
dride MnH(CO)nP5−n first with HBF4·Et2O or
CF3SO3H and then with an excess of the appropriate
hydrazine, as shown in Scheme 6.
Protonation of MnH(CO)nP5−n with HBF4·Et2O or
CF3SO3H proceeds with the formation of dihydrogen
complexes [10] [Mn(h2-H2)(CO)nP5−n]+, which in some
cases are thermally unstable and, after loss of H2, give
+
coordinatively unsaturated cations [Mn(CO)nP5−n
]
or
triflate complexes Mn(h1-OSO2CF3)(CO)nP5−n. Treat-
ment of solutions containing h2-H2 complexes or spe-
cies forming by loss of H2 with an excess of RNHNH2
affords hydrazine derivatives 9–15, which were isolated
as BPh4 salts and characterised.
Good analytical data were obtained for all hydrazine
complexes 9–15, which are white or pale yellow stable
solids, and soluble in polar organic solvents, in which
they behave as 1:1 electrolytes [12].
Diagnostic for the presence of the hydrazine ligand
(Table 1) were both IR spectra, showing the character-
istic w(NH) at 3371–3216 cm−1, and H-NMR ones,
1
which display two broad signals at 4.67–2.69 and 6.23–
2.22 ppm attributed to MnNH2 and NH2 or NH of the
RNHNH2 ligand. The IR and NMR data also allow us
to propose the geometries of Scheme 6 for hydrazine
complexes 9–15. Thus, the sharp singlet observed in the
31P{1H}-NMR spectra of monocarbonyls 9, 12, 14 sup-
ports a trans geometry, while a mer–cis one may be
proposed for dicarbonyls 10, 13, on the basis of the
AB2-type 31P{1H}-NMR spectra and of the presence of
two w(CO) strong bands observed in the IR spectra.
The inequivalence of the two carbonyls is confirmed by
the 13C{1H} spectra.
Preliminary studies on the reactivity of aryldiazenido
complexes 7 and 8 show that they are unreactive to-
wards HCl or other Brønsted acids, HX, and the start-
ing complex can be recovered unchanged after several
hours of reaction with a 20-fold excess of acid. This
unreactivity is rather surprising, since related
Mn(ArN2)(CO)2P2 complexes [5] containing PPh(OEt)2
or PPh2OEt phosphine ligands quickly react with HCl
to give aryldiazene derivatives MnCl(ArNꢀNH)(CO)2P2
In the temperature range between +20 and −80°C,
the 31P{1H} spectra of tricarbonyls 11, 15 are sharp

224
G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
Table 1
Infrared and NMR data for the manganese complexes
a
Compound
IR
1H-NMR b,c
Assignment l (J Hz)
Spin system 31P{1H}-NMR d,e
w (cm−1
)
Assignment
l (J Hz)
1a
1b
[Mn(C6H5NꢀNH)(CO){P(OMe)3}4]BPh4
[Mn(C6H5NꢀNH)(CO){P(OEt)3}4]BPh4
1899s
w(CO)
w(CO)
14.36 (s, br) NH
A4
A4
175.4 (s)
171.0 (s)
3.80 (br)
14.50 (qnt)
CH3
NH
1895s
J
PH=5
4.18 (m)
1.30 (t)
14.50 (dqnt) NH
CH2
CH3
1b1 [Mn(C6H5Nꢀ15NH)(CO){P(OEt)3}4]BPh4
1904s
w(CO)
A4
171.0 (s)
171.3 (s)
J15 =62
NH
J
=5
PH
4.18 (q)
1.30 (t)
CH2
CH3
1*b [Mn(4-CH3C6H4NꢀNH)(CO){P(OEt)3}4]BPh4 1894s
w(CO)
w(CO)
14.37 (s, br) NH
A4
4.19 (br)
2.40 (s)
1.30 (br)
CH2
CH3C6H4
POCH2CH3
2b
[Mn(C6H5NꢀNH)(CO)2{P(OEt)3}3]BPh4
1991s
1923s
14.15 (d, br) NH
PH=10
A2B f
lA 163.6
lB 155.4
J
4.35 (qnt)
4.15 (m)
1.41 (t)
1.28 (t)
14.14 (dd)
CH2
CH3
NH
JAB=101
2b1 [Mn(C6H5Nꢀ15NH)(CO)2{P(OEt)3}3]BPh4
1991s
1923s
w(CO)
A2BX f
lA 163.7
lB 155.4
J15 =62
NH
J
=10
JAB=101
PH
4.37 (qnt)
4.15 (m)
1.41 (t)
CH2
CH3
JAX, JBXB1
1.28 (t)
2c
3a
[Mn(C6H5NꢀNH)(CO)2{P(OPh)3}3]BPh4
[Mn(C6H5NꢀNH)(CO)3{P(OMe)3}2]BPh4
2017s
1960s
2066m
1984s
1974s
2063m
1986s
1971s
2064m
1986s
1972s
w(CO)
w(CO)
14.28 (d, br) NH
A2B
165–155 (m, br)
164.0 (s, br)
f
14.69 (s)
3.85 (t)
NH
CH3
A2
3b
[Mn(C6H5NꢀNH)(CO)3{P(OEt)3}2]BPh4
w(CO)
w(CO)
14.73 (s, br) NH
A2
159.3 (s)
4.24 (m)
1.29 (t)
14.74 (d)
J15 =65
4.2N3H(m)
1.29 (t)
CH2
CH3
NH
3b1 [Mn(C6H5Nꢀ15NH)(CO)3{P(OEt)3}2]BPh4
A2X
159.3 (s, br)
JAXB1
CH2
CH3
NH
3c
[Mn(C6H5NꢀNH)(CO)3{P(OPh)3}2]BF4
2090m
2019s
1982s
1905s
w(CO)
14.41 (s)
A2
157.8 (s)
4a
4b
[{Mn(CO)[P(OMe)3]4}2
(m-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)]ꢁ(BPh4)2
[{Mn(CO)[P(OEt)3]4}2
w(CO)
w(CO)
14.44 (s, br) NH
3.83 (t, br) CH3
14.56 (s, br) NH
A4
A4
175.2 (s)
170.9 (s)
1900s
1900s
(m-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)]ꢁ(BPh4)2
4.18 (br)
1.31 (br)
CH2
CH3
g
4b1 [{Mn(CO)[P(OEt)3]4}2
w(CO)
w(CO)
14.58 (dqnt) g NH
A4
170.8 (s, br)
171.0 (s)
(m-4,4%-H15NꢀNC6H4ꢁC6H4Nꢀ15NH)](BPh4)2
J15 =62
NH
3JPH=5
4.19 (m)
1.32 (t)
14.41 (qnt)
CH2
CH3
NH
4*b [{Mn(CO)[P(OEt)3]4}2
1908s
A4
(m-4,4%-HNꢀNC6H4ꢁCH2ꢁC6H4NꢀNH)](BPh4)2
J
PH=5
4.15 (m)
1.28 (t)
CH2
CH3

G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
225
Table 1 (Continued)
a
Compound
IR
1H-NMR b,c
Assignment l (J Hz)
Spin system 31P{1H}-NMR d,e
w (cm−1
)
Assignment
l (J Hz)
5b
[{Mn(CO)2[P(OEt)3]3}2
(m-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)](BPh4)2
1987s
1926s
w(CO)
14.23 (d, br) NH
PH=10
A2B f
lA 163.7
lB 155.4
JAB=101
h
J
4.38 (qnt)
4.18 (m)
1.43 (t)
CH2
CH3
1.29 (t)
5c
6a
[{Mn(CO)2[P(OPh)3]3}2
(m-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)](BPh4)2
[{Mn(CO)3[P(OMe)3]2}2
2017s
1961s
2070m
1991s
1968s
2065m
1985s
1969s
1949s
1875s
1650m
1589m
1618
1949s
1877s
1630m
1561m
1594
1957s
1870s
1617m
1570m
1593
1952s
1870s
1616m
1568m
1591
1963s
1886s
1637m
1587m
1609
3371w
3320w
3269w
3216w
1873s
3368m
3319w
3279w
1880s
3361w
3320m
3270w
1976s
1895s
3312w
3288w
3260w
3229w
2069w
1979s
1948s
w(CO)
w(CO)
14.33 (s, br) NH
A2B
A4
160–147 (m, br)
165.0 (s)
14.76 (s, br) NH
(m-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)](BPh4)2
3.87 (t, br)
CH3
6b
7c
[{Mn(CO)3[P(OEt)3]2}2
(m-4,4%-HNꢀNC6H4ꢁC6H4NꢀNH)](BPh4)2
w(CO)
w(CO)
14.82 (s, br) NH
4.24 (m, br) CH2
A4
159.3 (s)
179.9 (s)
1.31 (br)
CH3
f
Mn(C6H5N2)(CO)2[P(OPh)3]2
A2
w(N2)
w%(N2)
w(CO)
7c1 Mn(C6H5Nꢂ15N)(CO)2[P(OPh)3]2
A2X
180.8 (s) JAXB1
191.4 (s, br)
186.0 (s, br)
179.8 (s)
w(N+15N)
w%(N+15N)
w(CO)
f
8a
8b
8c
9a
9b
[Mn(CO)2{P(OMe)3}2]2
(m-4,4%-N2C6H4ꢁC6H4N2)
3.68 (t)
CH3
A2
w(N2)
w%(N2)
w(CO)
f
[Mn(CO)2{P(OEt)3}2]2
(m-4,4%-N2C6H4ꢁC6H4N2)
4.05 (m)
1.23 (t)
CH2
CH3
A2
w(N2)
w%(N2)
w(CO)
f
[Mn(CO)2{P(OPh)3}2]2
(m-4,4%-N2C6H4ꢁC6H4N2)
A2
w(N2)
w%(N2)
w(NH)
g
[Mn(NH2NH2)(CO){P(OMe)3}4]BPh4
[Mn(NH2NH2)(CO){P(OEt)3}4]BPh4
4.47 (m, br) g NH2
A4
175.2 (s, br)
173.8 (s, br)
3.27 (br)
MnNH2
3.70 (t, br)
CH3
w(CO)
w(NH)
3.20 (br) g
4.08 (m)
1.30 (t)
NH2
CH2
CH3
A4
f,g
w(CO)
w(NH)
10b [Mn(NH2NH2)(CO)2{P(OEt)3}3]BPh4
11a [Mn(NH2NH2)(CO)3{P(OMe)3}2]BPh4
3.86 (m, br) NH2
3.16 (m, br) MnNH2
A2B f
lA 164.3
lB 157.1
JAB=104
4.12 (m)
1.37 (t)
CH2
CH3
w(CO)
w(NH)
1.34 (t)
2.22 (br) i
2.69 (br)
3.82 (t, br)
NH2
MnNH2
CH3
A2
164.5 (s)
i
w(CO)

226
G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
Table 1 (Continued)
a
Compound
IR
1H-NMR b,c
Assignment l (J Hz)
Spin system 31P{1H}-NMR d,e
w (cm−1
)
Assignment
l (J Hz)
g
11b [Mn(NH2NH2)(CO)3{P(OEt)3}2]BPh4
3280w
3262m
3235w
2059w
1973s
1947s
3343w
3301w
1880s
3349w
3298w
1880s
w(NH)
w(CO)
w(NH)
2.51 (br) g
3.00 (br)
4.17 (m, br) CH2
1.40 (t, br) CH3
NH2
MnNH2
A2
160.3 (s)
g
g
12a [Mn(CH3NHNH2)(CO){P(OMe)3}4]BPh4
12b [Mn(CH3NHNH2)(CO){P(OEt)3}4]BPh4
3.35 (m, br) g MnNH2
2.52 (d)
A4
A4
175.7 (s)
NHCH3
POCH3
w(CO)
w(NH)
3.74 (br)
3.71 (m, br) g MnNH2
174.0 (s, br)
3.99 (m)
2.41 (d)
1.21 (t)
CH2
w(CO)
w(NH)
w(CO)
NHCH3
POCH2CH3
NH
MnNH2
CH2
13b [Mn(CH3NHNH2)(CO)2{P(OEt)3}3]BPh4
3342w
3309m
1993s
1900s
3.10 (m) g
3.79 (br)
4.13 (m)
2.57 (d)
1.35 (t)
A2B f,g
lA 163.9
lB 157.0
J
AB=100
NHCH3
POCH2CH3
1.31 (t)
14a [Mn(C6H5NHNH2)(CO){P(OMe)3}4]BPh4
14b [Mn(C6H5NHNH2)(CO){P(OEt)3}4]BPh4
3350w
3279w
1867s
3354m
3305w
3249w
1890s
1603m
3335m
3302m
3230w
2067m
1986s
w(NH)
4.15 (br)
3.78 (br)
MnNH2
CH3
A4
179.3 (s)
w(CO)
w(NH)
6.23 (t, br) g NH
4.67 (m, br) MnNH2
4.10 (m)
1.30 (t)
A4
171.8 (s, br)
f,g
CH2
CH3
w(CO)
l(NH2)
w(NH)
15a [Mn(C6H5NHNH2)(CO)3{P(OMe)3}2]BPh4
5.08 (t, br)
4.51 (m)
3.88 (t)
NH
MnNH2
CH3
A2
162.6 (s)
w(CO)
1953s
1600m
3285w
3250w
2065m
1983s
l(NH2)
w(NH)
f,g
16b [{Mn(CO)3[P(OEt)3]2}2(m-NH2NH2)](BPh4)2
17a [Mn(CH3NꢀNH)(CO){P(OMe)3}4]BPh4
4.49 (br) g
4.26 (m, br) CH2
1.46 (t) CH3
MnNH2
A2
156.5 (s)
w(CO)
w(CO)
1960s
1894s
f,g
13.8 (s, br) g NH
4.15 (s)
3.72 (br)
A4
174.0 (s, br)
CH3NꢀNH
POCH3
a In KBr pellets.
b In (CD3)2CO at 25°C, unless otherwise noted.
c Phenyl proton resonances are omitted.
d In (CD3)2CO at −90°C, unless otherwise noted.
e Positive shift downfield from 85% H3PO4.
f At 25°C.
g In CD2Cl2.
h 13C{1H}-NMR, lC: 222.4, 217.5 (4 C, m, CO), 165–120 (60 C, m, Ph), 63.32 (d), 62.76 (t) (18 C, CH2), 16.4 (18 C, s, br, CH3).
i In ClCD2CD2Cl.
singlets, indicating the magnetic equivalence of the two
phosphorus nuclei. The IR spectra show three w(CO)
bands (one medium, and two of strong intensity) in agree-
ment with a mer arrangement of the carbonyl ligands. On
this basis, a mer–trans geometry may be proposed for the
[Mn(NH2NHR)(CO)3P2]+ 11, 15 derivatives.
We also attempted to prepare binuclear complexes
with a hydrazine bridging ligand and, in the case of the
tricarbonyl species containing P(OEt)3 ligand, compound
[{Mn(CO)3P2}2(m-NH2NH2)](BPh4)2 (16b) was prepared
by treating MnH(CO)3P2 first with HBF4·Et2O and then
with NH2NH2, as reported in Scheme 7.

G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
227
The IR spectra of binuclear complex 16b show one
medium-intensity and two strong bands in the w(CO)
region, in agreement with a mer arrangement of the
three carbonyl ligands. The spectrum also contains only
two w(NH) bands at 3285 and 3250 cm−1 of the
NH2NH2 ligand. Furthermore, only one broad signal at
Support for this mer–trans geometry V comes from
the 31P{1H}-NMR spectra, which display a sharp sin-
glet between +20 and −80°C, indicating the magnetic
equivalence of the phosphorus nuclei. Furthermore,
analytical data agree with the binuclear formulation of
the complex, and comparisons between the spectro-
scopic data of 16b and the related mononuclear com-
plex [Mn(NH2NH2)(CO)3{P(OEt)3}2]BPh4 (11b) (Table
1) strongly support the presence of a bridging NH2NH2
ligand in a binuclear species with geometry V.
1
4.49 ppm appears in the H-NMR spectrum of com-
pound 16b, attributable to the NH2 protons. The pres-
ence of only one signal for the NH2 protons and of
only two w(NH) absorptions in the IR spectra strongly
suggest the presence of a binuclear complex with the
NH2NH2 bridging ligand of the geometry V type
(Scheme 8).
Oxidation of the hydrazine complexes with Pb(OAc)4
was studied extensively and, although the reaction pro-
ceeds with all the hydrazine complexes prepared (9–15),
Table 2
15N-NMR data for selected labelled compounds a,b
Compound
l (J Hz)
Assignment
15NH
1b1
2b1
[Mn(C6H5Nꢀ15NH)(CO){P(OEt)3}4]BPh4
[Mn(C6H5Nꢀ15NH)(CO)2{P(OEt)3}3]BPh4
43.6 (d, br)
1J15 =62
33.1NH(dq)
15NH
1J15 =62
NH
2J15
2J15
=8
NPcis
=8
3b1
4b1
[Mn(C6H5Nꢀ15NH)(CO)3{P(OEt)3}2]BPh4
22.6NP(dtra,nsbr)
1J15 =65
42.9NH(dqnt)
1J15 =62
2J15NH=8
15NH
15NH
[{Mn(CO)[P(OEt)3]4}2(m-4,4%-H15NꢀNC6H4ꢁC6H4Nꢀ15NH)](BPh4)2
7c1
Mn(C6H5Nꢂ15N)(CO)2[P(OPh)3]2
62.8NP(t, br)
ꢁ
15N
a In CD2Cl2 at 25°C.
b Positive shift downfield from CH315NO2.
Scheme 3. P=P(OMe)3 (a), P(OEt)3 (b) or P(OPh)3 (c); Ar=C6H5; ArꢁAr=4,4%-C6H4ꢁC6H4.

228
G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
Pb(OAc)4 to give a yellow solution from which only
decomposition products were obtained. Instead, the
reaction of related methylhydrazine complexes 12, 13
proceeds with selective oxidation of the CH3NHNH2
ligand, to give the corresponding methyldiazene
+
[Mn(CH3NꢀNH)(CO)nP5−n
P(OMe)3 derivative
]
which, in the case of the
[Mn(CH3NꢀNH)(CO){P-
(OMe)3}4]BPh4 (17a), was isolated in the solid state and
characterised. In the other cases, instead, the complexes
were rather unstable and decomposed during crystalli-
sation.
Methyldiazene complexes are rare [4a,18], and the
use of the Mn(CO)[P(OMe)3]4 fragment allows the
preparation of the unprecedented manganese
derivative.
Scheme 4.
Scheme 5.
Phenylhydrazine complexes 14, 15 were also oxidised
by Pb(OAc)4 to give the corresponding aryldiazene
+
[Mn(C6H5NꢀNH)(CO)nP5−n
]
cations which, how-
ever, were isolated in the solid state as a mixture of
products. Since the same complexes (1–3) were ob-
tained from the reaction of hydrides MnH(CO)nP5−n
with phenyldiazonium cations and were rather stable
both as solids and in solution, the mixture obtained
from oxidation cannot be formed by decomposition of
the aryldiazene complex, but rather by oxidation
byproducts of the hydrazine complexes. However, com-
pound [Mn(C6H5NꢀNH)(CO){P(OEt)3}4]BPh4 (1b) was
isolated in pure form, and its spectroscopic properties
are identical to those of a sample prepared by reacting
hydride MnH(CO)[P(OEt)3]4 with C6H5N+2 BF4− and
this feature, together with the analytical data, confirms
its formulation.
1
In the high field region, the H-NMR spectrum of
Scheme 6. P=P(OMe)3 (a), P(OEt)3 (b) or P(OPh)3 (c); n=1, R=H
(9a–b); n=1, R=CH3 (12a–b); n=1, R=C6H5 (14a–b); n=2,
R=H (10b); n=2, R=CH3 (13b); n=3, R=H (11a–b); n=3,
R=C6H5 (15a).
methyldiazene complex 17a shows one slightly broad
signal at 13.8 ppm, characteristic of a diazene ligand. In
the temperature range between +30 and −80°C, the
31P{1H}-NMR spectrum shows a sharp singlet, in
agreement with the presence of four equivalent phos-
phite ligands. The IR spectrum shows only one w(CO)
Scheme 7. P=P(OEt)3.
Scheme 8.
only in two cases were the related diazene derivatives
isolated in pure form and characterised (Scheme 9).
Hydrazine complexes 9, 10, 11 react at −30°C with
Scheme 9.

G. Albertin et al. / Journal of Organometallic Chemistry 625 (2001) 217–230
229
band at 1894 cm−1. On these bases, a trans geometry
(VI) of the type reported in Scheme 9 can be proposed
for our methyldiazene derivative.
[3] For recent papers on ‘diazo’ complexes see: (a) L. Fan,
F.W.B. Einstein, D. Sutton, Organometallics 19 (2000) 684. (b)
X. Yan, R.J. Batchelor, F.W.B. Einstein, X. Zhang, R.
Nagelkerke, D. Sutton, Inorg. Chem. 36 (1997) 1237. (c) N.
Lehnert, B.E. Wiesler, F. Tuczek, A. Hennige, D. Sellmann, J.
Am. Chem. Soc. 119 (1997) 8869. (d) M. Hirsch-Kuchma, T.
Nicholson, A. Davison, W.M. Davis, A.G. Jones, Inorg.
Chem. 36 (1997) 3237. (e) A. Garcia-Minsal, D. Sutton,
Organometallics 15 (1996) 332. (f) D.J. Rose, K.P. Maresca,
P.B. Kettler, Y.D. Chang, V. Saghomomian, Q. Chen, M.J.
Abrams, S.K. Larsen, J. Zubieta, Inorg. Chem. 35 (1996)
3548. (g) A. Cusanelli, D. Sutton, Organometallics 14 (1995)
4651. (h) P.B. Kettler, Y.-D. Chang, J. Zubieta, Inorg. Chem.
33 (1994) 5864. (i) G.C.-Y. Kim, R.J. Batchelor, X. Yan,
F.W.B. Einstein, D. Sutton, Inorg. Chem. 34 (1995) 6163. (j)
K.D. Demadis, S.M. Malinak, D. Coucouvanis, Inorg. Chem.
35 (1996) 4038. (k) T.-Y. Cheng, A. Ponce, A.L. Rheingold,
G.L. Hillhouse, Angew. Chem. Int. Ed. Engl. 33 (1994) 657.
(l) D. Sellmann, J. Ka¨ppler, M. Moll, F. Knoch, Inorg. Chem.
32 (1993) 960. (m) T.E. Glassman, M.G. Vale, R.R. Schrock,
J. Am. Chem. Soc. 114 (1992) 8098. (n) M. Kawano, C.
Hoshino, K. Matsumoto, Inorg. Chem. 31 (1992) 5158. (o) S.
Vogel, A. Barth, G. Huttner, T. Klein, L. Zsolnai, R. Kremer,
Angew. Chem. Int. Ed. Engl. 30 (1991) 303.
[4] (a) G. Albertin, S. Antoniutti, A. Bacchi, D. Barbera, E. Bor-
dignon, G. Pelizzi, P. Ugo, Inorg. Chem. 37 (1998) 5602. (b)
G. Albertin, S. Antoniutti, A. Bacchi, M. Bergamo, E. Bor-
dignon, G. Pelizzi, Inorg. Chem. 37 (1998) 479. (c) G. Al-
bertin, S. Antoniutti, E. Bordignon, S. Pattaro, J. Chem. Soc.
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Bacchi, E. Bordignon, P.M. Dolcetti, G. Pelizzi, J. Chem. Soc.
Dalton Trans. (1997) 4435. (e) G. Albertin, S. Antoniutti, A.
Bacchi, E. Bordignon, G. Pelizzi, P. Ugo, Inorg. Chem. 35
(1996) 6245.
4. Conclusions
This contribution highlights the influence of phos-
phine ligands in the chemistry of ‘diazo’ complexes of
manganese. In particular, the use of phosphite P(OR)3
allows a large series of mono [Mn(ArNꢀNH)(CO)n-
+
P5−n
]
and binuclear [{Mn(CO)nP5−n}2(m-HNꢀNArꢁ
ArNꢀNH)]2+ aryldiazene complexes to be prepared.
However, in contrast with previous reports [5] on phos-
phonite, PPh(OEt)2, and phosphinite, PPh2OEt, lig-
ands, all the Mn(CO)nP5−n fragments with CO:P ratios
ranging from 3:2 to 1:4 stabilise the ArNꢀNH ligand.
Phosphite also stabilises pentacoordinate aryldiazenido
complexes containing bis(carbonyl)bis(phosphite) lig-
ands of the type Mn(ArN2)(CO)2P2 and [Mn(CO)2P2]2-
(m-N2ArꢁArN2). Lastly, new hydrazine complexes
[Mn(RNHNH2)(CO)nP5−n]BPh4 were prepared and
their oxidation with Pb(OAc)4 led to the corresponding
+
substituted-diazene
[Mn(RNꢀNH)(CO)nP5−n]
cations, including the first example of a methyldiazene
[Mn(CH3NꢀNH)(CO){P(OMe)3}4]+ derivative for this
metal.
[5] G. Albertin, S. Antoniutti, A. Bacchi, E. Bordignon, F.
Busatto, G. Pelizzi, Inorg. Chem. 36 (1997) 1296.
[6] (a) C.F. Barrientos-Penna, F.W.B. Einstein, D. Sutton, A.C.
Willis, Inorg. Chem. 19 (1980) 2740. (b) G. Ferguson, W.J.
Laws, M. Parvez, R.J. Puddephatt, Organometallics 2 (1983)
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Organomet. Chem. 137 (1977) C11. (h) W.A. Herrmann, M.L.
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Acknowledgements
The financial support of the Ministero della Ricerca
Scientifica e Tecnologica, Rome-Programmi di Ricerca
Scientifica di Rilevante Interesse Nazionale, Cofinanzia-
mento 1998/1999 is gratefully acknowledged. We thank
Daniela Baldan for technical assistance.
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