Orthomanganation of arylhydrazones and related N-donor substrates

Article abstract of DOI:10.1016/S0022-328X(98)00453-7

The N-phenyl- and N,N-diphenylhydrazones of benzaldehyde or acetophenone are readily cyclometallated on reaction with PhCH₂Mn(CO)₅ to give complexes 3 of the type (OC)₄MnC₆H₄C(R¹)=NNPhR² incorporating a five-membered MnC₃N ring. The example with R¹=Me, R²=H has been structurally characterised. The similar reaction with the N,N-diphenylhydrazone of cyclohexanone produces a species with an alternative MnC₂N₂ ring which was also structurally characterised. A related species (OC)₄MnC₆H₄NN=O is formed from N-nitrosodiphenylamine. Reactions of compounds 3 from the diphenylhydrazones with alkynes PhCCPh or Me₃SiCCH give N′-indenyl-N,N-diphenylhydrazines in reasonable yields.

Full text of DOI:10.1016/S0022-328X(98)00453-7

Journal of Organometallic Chemistry 565 (1998) 125–134
Orthomanganation of arylhydrazones and related N-donor substrates1
Maarten B. Dinger, Lyndsay Main, Brian K. Nicholson *
School of Science and Technology, Uni6ersity of Waikato, Pri6ate Bag 3105, Hamilton, New Zealand
Received 27 November 1997
Abstract
The N-phenyl- and N,N-diphenylhydrazones of benzaldehyde or acetophenone are readily cyclometallated on reaction with
¸¹¹¹¹¹¹¹¹º
¸¹¹º
PhCH2Mn(CO)5 to give complexes 3 of the type (OC)4MnC6H4C(R1)ꢀNNPhR2 incorporating a five-membered MnC3N ring. The
example with R1=Me, R2=H has been structurally characterised. The similar reaction with the N,N-diphenylhydrazone of
¸¹¹º
cyclohexanone produces a species with an alternative MnC2N2 ring which was also structurally characterised. A related species
¸¹¹¹¹º
(OC)4MnC6H4NNꢀO is formed from N-nitrosodiphenylamine. Reactions of compounds 3 from the diphenylhydrazones with
alkynes PhCꢁCPh or Me3SiCꢁCH give N%-indenyl-N,N-diphenylhydrazines in reasonable yields. © 1998 Elsevier Science S.A. All
rights reserved.
Keywords: Orthometallation; Manganese; Arylhydrazones; Alkyne reactions
1. Introduction
pyridines [20,21], N-benzylideneamines (imines) [22–
29], azines [30,31] and hydrazones [30–33] have all
been used to give palladium derivatives, and their
reactivities have been studied.
Cyclometallation is now a standard procedure for
activating C–H bonds. Michael Bruce provided the
first comprehensive review of the area in 1977 [1],
and this has provided a useful basis for much of the
subsequent work, as demonstrated by the fact that it
is still regularly cited 20 years later. Later reviews
have covered selected areas of cyclometallation chem-
istry as the range of substrates and metals involved
has increased, and as applications of cyclometallated
compounds in synthesis have been increasingly devel-
oped [2–9].
We have been developing the chemistry of cyclo-
manganated complexes of type 2, especially those
derived from aryl ketones and enones where O is the
donor atom [9,34,35], and from triphenylphosphine
chalcogenides where O, S or Se is also attached to
the C-bonded manganese atom [36]. During the
course of these studies we noted that there had been
little development of cyclomanganation chemistry in-
volving N-donor substrates, despite the fact that these
were the earliest examples reported for manganese,
mainly by Bruce et al. [37–42] who studied benzyl
The best developed area is probably that involving
cyclopalladation of aromatic substrates incorporating
an N-donor, giving complexes of type 1. Substituted
azobenzenes [10–12], benzylamines [13–19], aryl–
* Corresponding author.
1 Dedicated to Michael Bruce, a good friend and colleague, on the
occasion of his 60th birthday.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00453-7

126
M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
amines, aryl–imines and azobenzenes. This has meant
that the reactivity of related cyclomanganated and cy-
clopalladated complexes has rarely been directly com-
pared [30], since palladium does not readily form
cyclometallated complexes with the O-donor ketones
that represent the best developed chemistry for man-
ganese.
We now report the preparation, structures and se-
lected reactions of new compounds formed by cyclo-
manganation of N-arylhydrazones and related
substrates.
2.2.2. Cyclomanganation of acetophenone
phenylhydrazone
Similarly, PhC(Me)ꢀNNHPh (0.213 g, 1.16 mmol)
and PhCH2Mn(CO)5 (0.332 g, 1.01 mmol) in refluxing
heptane (30 ml) for 2 h gave an orange oil which was
crystallised from CHCl3 to yield orange crystals of
p2-(N,C)-2-[1-N-phenylhydrazono)ethyl]phenyltetracar-
bonylmanganese, 3b, (0.334 g, 87%), m.p. 76–77°C.
Anal.: Found
C
57.31,
H
3.40,
N
7.39%;
C18H13N2O4Mn requires C 57.46, H 3.48, N 7.45%. IR
w(CO) (heptane, cm−1): 2071 m, 1988 s, 1980 vs, 1947
s. UV–vis (hexane): umax 340 nm. 1H-NMR: l 8.01
(1H, d, br, H-6%), 7.67 (1H, d, br, H-3%), 7.34 (2H, t, br,
H-3%%,5%%), 7.25 (2H, d, br, H-2%%,6%%), 7.06 (1H, t, br,
H-4%%), 6.66 (1H, t, br, H-5%), 6.05 (1H, t, br, H-4%), 5.30
(1H, s, br, N–H), 2.53 (3H, s, br, H-2). 13C-NMR: l
219.5 (s, CꢁO), 213.5 (s, CꢁO), 212.7 (s, CꢁO), 186.9 (s,
C-1%), 180.4 (s, C-1), 145.9 (s, C-1%%), 144.7 (s, C-2%),
141.4 (d, C-6%), 131.4 (d, C-3%), 129.6 (d, C-3%%,5%%), 129.0
(d, C-5%), 123.9 (d, C-4%), 122.3 (d, C-4%%), 114.8 (d,
C-2%%,6%%), 15.5 (q, C-2).
2. Experimental details
2.1. General
Samples of PhCH2Mn(CO)5 (m.p. 34–36°C, lit.
37.5–38.5°C [43]), the phenylhydrazones of benzalde-
hyde (m.p. 155–156°C) and acetophenone (m.p. 105–
106°C), the diphenylhydrazones of benzaldehyde (m.p.
114–116°C), acetophenone (m.p. 93–94°C) and cyclo-
hexanone (m.p. 72–74°C) and diphenylnitrosamine
[CARE: toxicity hazard, carcinogen] (m.p. 66–67°C)
were prepared by standard methods and their purity
2.2.3. Cyclomanganation of benzaldehyde
diphenylhydrazone
Similarly, PhCHꢀNNPh2 (0.304 g, 1.12 mmol) and
PhCH2Mn(CO)5 (0.352g, 1.23 mmol) in refluxing hep-
tane (30 ml) for 2.5 h gave a yellow solid which was
recrystallised from CHCl3 to yield a yellow powder of
p2 -(N,C)-2-(N,N-diphenylhydrazonomethyl)phenylte-
tracarbonylmanganese, 3c (0.395 g, 83%), m.p. 105–
106°C. Anal.: Found C 62.96, H 3.29, N 6.34%;
C23H15N2O4Mn requires C 63.03, H 3.45, N 6.39%;
1
was established by H- and 13C-NMR spectroscopy and
by melting points [44]. The N-phenylhydrazones were
stored under nitrogen at low temperature to minimise
their ready autoxidation [45].
2.2. Cyclomanganation reactions
w(CO) (heptane, cm−1) 2074 m, 1985 vs, 1950 s. H-
1
2.2.1. Cyclomanganation of benzaldehyde
phenylhydrazone
NMR: l 7.66–7.09 (16H, m, C–H aromatic), 2.15 (1H,
s, H-1). 13C-NMR: l 143.8 (s, C-1%%), 136.2 (s, C-1%),
135.6 (d, C-1), 129.8 (d, C-3%%,5%%), 128.6 (d, C-2%,6%),
128.1 (d, C-4%), 126.4 (d, C-3%,5%), 124.5 (d, C-4%%), 122.6
(d, C-2%%,6%%).
A sample of PhCHꢀNNHPh (0.189 g, 0.962 mmol)
and PhCH2Mn(CO)5 (0.295 g, 1.03 mmol) was added to
heptane (25 ml). The mixture was degassed and flushed
with nitrogen, before bringing to reflux for 2 h. The
initially yellow solution changed through orange to
deep red. Solvent was removed under vacuum to leave
a dark oil. This was dissolved in CH2Cl2 and alumina
(Brockmann grade II) was added. The CH2Cl2 was
removed under vacuum and the residue was transferred
to the top of an alumina column. Elution with
petroleum spirit gave some Mn2(CO)10, while petroleum
spirit/CH2Cl2 removed a deep orange band of p2-(N,C)-
2-(N-phenylhydrazonomethyl)phenyltetracarbonylman-
ganese, 3a (0.267 g, 77%) as an oil which could not be
crystallised. IR w(CO) (heptane, cm−1): 2077 m, 1994 s,
2.2.4. Cyclomanganation of acetophenone
diphenylhydrazone
Similarly, PhC(Me)=NNPh2 (0.401 g, 1.40 mmol)
and PhCH2Mn(CO)5 (0.420 g, 1.468 mmol) in refluxing
heptane (30 ml) for 2 h gave a dark solution. Work-up
gave a major yellow band which was crystallised from
petroleum spirit/CHCl3 as a yellow powder of p2-
(N,C)-2-[1-(N,N-diphenylhydrazono)ethyl]phenyltetra-
carb onylmanganese, 3d, (0.541 g, 86%), m.p. 88–9°C.
Anal.: Found
C
63.73,
H
3.68,
N
6.17%;
C24H17N2O4Mn requires C 63.73, H 3.79, N 6.19%. IR
w(CO) (heptane, cm−1): 2071 m, 1988 s, 1980 vs, 1947
s. UV–vis (hexane): umax 362 nm (br). 1H-NMR: l
7.97–7.13 (15H, m, C–H aromatic), 2.35 (3H, s, H-2).
13C-NMR: l 213.5 (s, CꢁO), 188.7 (s, C-1%), 182.9 (s,
C-1), 145.2 (s, C-1%), 143.5 (s, C-1%%), 141.4 (d, C-6%),
131.4 (d, C-3%), 129.5 (d, C-3%%,5%%), 123.9 (d, C-4%), 123.4
(d, C-4%%), 120.1 (d, C-2%%,6%%), 17.0 (q, C-2).
1
1985 vs, 1947 s. H-NMR: l 8.38 (1H, s, H-1), 7.98
3
(1H, d, J6%,5%=5.37Hz, H-6%), 7.56–7.03 (13H, m, C–H
aromatic). 13C-NMR: l 220.2 (s, CꢁO), 213.7 (s, CꢁO),
211.5 (s, CꢁO), 181.7 (s, C-1%), 173.6 (d, C-1), 145.1 (s,
C-1%%), 144.7 (s, C-2%), 141.2 (d, C-6%), 130.5 (d, C-3%),
129.6 (d, C-3%%,5%%), 124.9 (d, C-4%%), 124.0 (d, C-4%), 123.4
(d, C-2%%,6%%).

M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
127
2.2.5. Cyclomanganation of cyclohexanone
diphenylhydrazone
that all of 3c had been consumed to be replaced by
w(CO) bands at 2024m, 1982w, 1919 vs cm−1. The
solvent was removed under vacuum, the residue was
dissolved in CH2Cl2, and alumina (Brockmann grade
II) was added. The CH2Cl2 was pumped off and the
resulting powder was transferred to the top of an
alumina column (8.0×2.5 cm). Elution with petroleum
spirit gave unreacted Ph2C2, identified by NMR. Elu-
tion with petroleum spirit:CH2Cl2 (7:3) gave an orange
band which was crystallised from petroleum spirit as an
orange powder identified as the indenyl diphenylhy-
drazine 7a, (0.133 g, 53%). Anal.: Found C 86.96, H
5.60, N 6.19%; C33H25N2 requires C 87.16, H 5.60, N
6.23%. 1H-NMR: l 7.33–6.91 (24H, m, C–H aro-
matic), 4.48 (1H, s, C-1). 13C-NMR: l 148.0 (s), 144.9
(s), 144.6 (s), 141.4 (s), 140.9 (s), 134.8 (s) 134.0 (s),
131.5 (s), 129.4 (d), 129.1 (d) 128.6 (d), 128.4 (d), 127.7
(d), 127.4 (d) 126.0 (d), 124.8 (d), 122.8 (d), 121.3 (d)
121.1 (d), 120.6 (d), 117.9 (d), 64.2 (d).
A sample of C6H10NNPh2 (0.282 g, 0.986 mmol) and
PhCH2Mn(CO)5 (0.248 g, 0.938 mmol) was heated un-
der reflux in heptane (25 ml) for 2 h. to give a yellow
solution. Chromatographic work-up as in Section 2.2.1
gave one major band which was recrystallised from
petroleum spirit/CH2Cl2 as yellow crystals of p2-(N,C)-
2-(N2-cyclohexylidene-N1-phenylhydrazino)phenyltetra-
carbonylmanganese, 4 (0.379 g, 94%), m.p. 110–112°C.
Anal.: Found
C
61.19,
H
4.36,
N
6.40%;
C22H19N2O4Mn requires C 61.40, H 4.45, N 6.51%. IR
w(CO) (heptane, cm−1): 2073 m, 1991 vs, 1977 s, 1940
s. 1H-NMR: l 7.90–7.82 (1H, m, C–H aromatic),
7.23–6.70 (m, C–H aromatic), 2.99–2.80 (m, C–H
cyclohexyl), 1.92–1.43 (m, C–H cyclohexyl). 13C-
NMR: l 220.4 (s, CꢁO), 214.2 (s, CꢁO), 212.4 (s, CꢁO),
191.7 (s, C-1), 160.6 (s, C-1%), 151.3 (s, C-2%), 145.0 (s,
C-1%%), 141.7 (d, C-6%), 129.2 (d, C-3%%,5%%), 125.8 (d, C-4%),
123.8 (d, C-5%), 121.9 (d, C-4%%), 120.4 (d, C-3%), 113.6 (d,
C-2%%,6%%), 38.8 (t, C-6), 32.3 (t, C-2), 26.9 (t, C-4), 26.4
(t, C-5), 24.9 (t, C-3).
2.3.2. Reaction of p2-(N,C)-2-(N,N-diphenylhy-
drazonomethyl)phenyltetracarbonylmanganese, 3c, with
Me3SiC2H
2.2.6. Cyclomanganation of diphenylnitrosamine
Following the same work-up procedure after a 4 h
reflux, the major yellow band to be eluted with
petroleum spirit:CH2Cl2 (10:1) was identified spectro-
scopically as an inseparable 2:1 mixture of the two
isomers 7b and 7c in total 54% yield. 1H-NMR: l
7.73–7.08 (15H, m, C–H aromatic), 1.62 (1H, s, C-1),
A sample of Ph2NNO (0.201 g, 1.01 mmol) and
PhCH2Mn(CO)5 (0.303g, 1.06 mmol) in refluxing hep-
tane (30 ml) for 0.5 h gave, after the standard work-up,
p2-(N,C)-2-[N-nitroso-N-phenylamino]phenyltetracarb-
onylmanganese, 5 (0.258 g, 70%). Recrystallisation
from petroleum spirit gave orange–brown crystals,
m.p. 65–66°C. Anal.: Found C 56.33, H 3.22, N 7.75%;
C16H9N2O5Mn·0.25Ph2NH requires C 56.17, H 2.85, N
7.23%. IR w(CO) (heptane, cm−1): 2084 m, 2004 s,
1.46 (1H, s, C-1), 0.37 (9H, s, Si(CH3 3
6 ) ), 0.24 (9H, s,
Si(CH3 3
6
) ). 13C-NMR: l 143.8 (s), 141.2 (s), 134.2 (s),
133.3 (s), 129.9 (d), 129.1 (d), 127.8 (s), 128.1 (s), 1 (s),
126.7 (s), 126.2 (s), 124.6 (d), 122.6 (d), 121.0 (d), 29.8
1
3
2001vs, 1970 s. H-NMR: l 7.93 (1H, d, J6%,5%=1.79
(d), 22.8 (d), −0.7 (q, Si(C6 H3)3), −1.17 (q, Si(C6 H3)3).
3
Hz, H-6%), 7.86 (1H, t, J4%,5%=1.79 Hz), 7.57–7.51 (3H,
m, C–H aromatic), 7.28–6.95 (4H, m, C–H aromatic).
13C-NMR: l 219.7 (s, CꢁO), 211.0 (s, CꢁO), 210.0 (s,
CꢁO), 156.4 (s, C-1%), 147.8 (s, C-2%), 141.6 (d, C-6%),
135.1 (s, C-1%%), 130.9 (d, C-3%), 130.3 (d, C-3%%,5%%), 127.5
(d, C-2%%,6%%), 127.1 (d, C-4%), 124.8 (d, C-4%%), 114.8 (d,
C-3%). Diphenylamine impurity peaks (ca. 25%): l 143.2
(s, C-1), 129.4 (d, C-3,5), 121.1 (d, C-4), 117.9 (d,
C-2,6). Electrospray mass spectroscopy, ESMS
(MeCN/H2O, 1:1, cone voltage 10V): m/z 382 (21%)
[M+NH4]+, 365 (100%) [M+H]+, 336 (13%) [M+
NH4−2CO]+, 170 (33%) [Ph2NH2]+.
2.3.3. Reaction of p2-(N,C)-[1-(N,N-diphenylhy-
drazono)ethyl]phenyl-tetracarbonylmanganese, 3d, with
Ph2C2
This reaction, after a 3 h reflux, gave a major orange
band with petroleum spirit:CH2Cl2 (3:7) which crys-
tallised from petroleum spirit to give the analogous
hydrazine 8a, 42%, m.p. 127°C, identified spectroscopi-
1
cally. H-NMR: l 7.62–7.11 (24H, m, C–H aromatic),
3.06 (3H, s, C-1). 13C-NMR: l 157.7 (s), 149.5 (s), 137.7
(s), 136.0 (s), 131.4 (d), 130.3 (d) 129.9 (d), 129.3 (s),
128.2 (d), 127.6 (d), 127.1 (d) 126.9 (d), 126.5 (d), 126.3
(d), 125.5 (d), 22.76 (q, C6 H3).
2.3. Reactions of orthomanganated complexes with
alkynes
2.3.4. Reaction of p2-(N,C)-[1-(N,N-diphenylhy-
drazono)ethyl]phenyl-tetracarbonylmanganese, 3d, with
Me3SiC2H
Following the same procedure, but for a 5 h reflux,
the major yellow band to be eluted with petroleum
spirit:CH2Cl2 (3:1) gave an impure yellow oil that could
not be further purified, but which NMR spectroscopy
suggested contained the hydrazine 8b as the major
2.3.1. Reaction of p2-(N,C)-2-(N,N-diphenylhy-
drazonomethyl)phenyltetracarbonylmanganese, 3c, with
Ph2C2
Compound 3c (0.251 g, 0.573 mmol) and Ph2C2 (0.20
g, 1.12 mmol) were heated under reflux in acetonitrile
(25 ml) for 2 h; by this time an IR spectrum showed

128
M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
component. 1H-NMR: l 7.35–6.89 (15H, m, C–H arom-
atic), 2.02 (3H, s, C-1), 0.11 (9H, s, Si(CH3 3
) ). 13C-NMR:
l 168.3 (s), 148.7 (s), 141.9 (d), 139.4 (s), 136.9 (s), 132.8
Table 1
Atomic coordinates and equivalent isotropic displacement parameters
for p2-2-[1-(N-phenylhydrazono)ethyl]phenyltetracarbonylmanganese
(3b)
6
(d), 129.3 (d), 128.7 (d), 128.2 (d), 127.8 (d), 126.4 (d),
123.4 (d), 121.8 (d), 22.6 (q, C-1), −1.2 (q, Si(C
Impurity resonances: l 129.4 (d), 121.6 (d), 117.9 (d).
6
H3)3).
Atom
x
y
z
U(eq)
Mn(1)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
O(1)
O(2)
0.2777(1)
0.2885(2)
0.2643(2)
0.2781(3)
0.4393(3)
0.1184(3)
0.2154(3)
0.2843(2)
0.5416(2)
0.0231(2)
0.1757(2)
0.3394(2)
0.3487(2)
0.3875(2)
0.4191(2)
0.4102(2)
0.3713(2)
0.3174(2)
0.3200(3)
0.1394(2)
0.1053(3)
0.1688(1)
0.2904(3)
0.2278(3)
0.0915(3)
0.1100(3)
0.2453(3)
0.5755(1)
0.4772(1)
0.4035(1)
0.6698(2)
0.5758(2)
0.5871(2)
0.5279(2)
0.7315(1)
0.5813(1)
0.5974(1)
0.4983(1)
0.6156(2)
0.5580(2)
0.5741(2)
0.6479(2)
0.7054(2)
0.6894(2)
0.4808(2)
0.4137(2)
0.3738(2)
0.3187(2)
0.2838(2)
0.3035(2)
0.3589(2)
0.3945(2)
0.020(1)
0.020(1)
0.022(1)
0.025(1)
0.022(1)
0.025(1)
0.024(1)
0.036(1)
0.030(1)
0.034(1)
0.035(1)
0.019(1)
0.019(1)
0.023(1)
0.025(1)
0.026(1)
0.022(1)
0.020(1)
0.025(1)
0.019(1)
0.025(1)
0.029(1)
0.028(1)
0.026(1)
0.022(1)
2.3.5. Unsuccessful reactions
The following reactions were carried out, all of which
gave complex mixtures of products which were not able
to be characterised:
1. the mono-phenylhydrazones 3a and 3c with Ph2C2,
2. the di-phenylhydrazones 3b and 3c with
C2(COOMe)2 and
−0.0063(4)
0.0500(3)
0.0737(2)
0.2910(2)
−0.1142(3)
0.3785(3)
0.4896(3)
0.6398(3)
0.6830(3)
0.5761(3)
0.4270(3)
0.4356(3)
0.5391(3)
0.2256(3)
0.1170(3)
0.1176(4)
0.2269(4)
0.3322(3)
0.3332(3)
O(3)
O(4)
3. the cyclohexylidene complex 4 with Ph2C2 or
PhC2H.
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
2.4. X-ray crystal structure determinations
Accurate cell parameters and intensity data were
obtained on a Nicolet XRD P3 four-circle diffractometer
(for 3b and 5) or an Enraf-Nonius CAD4 four-circle
diffractometer (for 4) with monochromated Mo–Kh
˚
X-rays (u=0.71073 A). The structures were solved by
−0.0117(3)
−0.0968(3)
−0.0646(2)
0.0536(2)
direct methods (SHELXS-86 [46]) and the refinement was
based on F2 (SHELXL-93 [47]). All non-H atoms were
refined anisotropically and H atoms were included in
calculated positions.
Tables 1 and 2, respectively, and the structure is illus-
trated in Fig. 1.
2.4.1. p2-2-[1-(N-Phenylhydrazono)
ethyl]phenyltetracarbonylmanganese (3b)
Orange crystals of 3b were obtained from CHCl3.
Crystal data: C18H13MnN2O4, Mr=376.24, monoclinic,
space group P21/c, a=10.878(2), b=8.712(2), c=17.765
3
˚
˚
(4) A, i=93.78(3)°, V=1679.9(6) A , Dcalc. =1.488 g
cm−3, Z=4, F(000)=768, v(Mo–Kh)=0.811 mm−1
,
Tmax 0.79, Tmin 0.69. Crystal size 0.48×0.46×0.16 mm3.
A total of 2333 reflections (2197 unique) were collected
at −143°C, 4°B2qB45°, 1838 with I\2|(I). The
refinement converged with R1=0.0317 (2| data), and
R1=0.0430, wR2=0.0767, GoF=1.047 (all data). Final
−3
˚
largest D/| 0.001, largest final feature 0.37 e A
Coordinates and selected bond parameters are listed in
.
Table 2
Selected bond parameters for p2-2-[1-(N-phenylhydrazono)ethyl]phenyltetracarbonyl-manganese (3b)
˚
Bond lengths (A)
Mn(1)–C(11)
Mn(1)–C(2)
C(11)–C(12)
N(1)–N(2)
2.058(3)
1.830(3)
1.416(4)
1.427(3)
Mn(1)–N(1)
Mn(1)–C(3)
C(12)–C(17)
2.053(2)
1.881(3)
1.469(4)
Mn(1)–C(1)
Mn(1)–C(4)
N(1)–C(17)
1.806(3)
1.851(3)
1.303(4)
Bond angles (°)
N(1)–Mn(1)–C(11)
Mn(1)–N(1)–C(17)
C(11)–C(12)–C(17)
N(1)–C(17)–C(12)
78.5(1)
119.2(2)
115.6(2)
113.3(2)
Mn(1)–N(1)–N(2)
Mn(1)–C(11)–C(12)
Mn(1)–C(11)–C(16)
C(2)–Mn(1)–C(3)
124.5(2)
113.2(2)
130.3(2)
172.1(1)

M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
129
Fig. 1. A PLUTO-plot of the structure of the orthomanganated complex of acetophenone–phenylhydrazone, 3b.
The refinement converged with R1=0.0332 (2| data),
and R1=0.0356, wR2=0.0891, GoF=1.054 (all data).
lattice, approximating 0.25 C6H6 which presumably can
be attributed to the co-crystallising Ph2NH which was
also indicated from the NMR and micro-analytical data
(see text). However this was not very successfully mod-
elled and combined with the weak data set from a poorly
diffracting crystal, the structure was less precisely defined
than usual. The refinement converged with R1=0.1297
(2| data) and wR2=0.4514, GoF=1.031 (all data).
−3
˚
Final largest D/| 0.001, largest final feature 0.54 e A
.
The Flack x parameter refined to −0.004(14) indicating
the correct polarity was chosen. Coordinates and selected
bond parameters are listed in Tables 3 and 4, respectively,
and the structure is illustrated in Fig. 2.
2.4.3. p2-2-(N1-Nitroso-N1-phenyla-
−3
˚
Final largest D/| 0.001, largest final feature 1.86 e A
.
mino)phenyltetracarbonylmanganese (5)
Orange crystals were obtained by diffusion of pentane
into a CH2Cl2 solution of 5.
The structure is illustrated in Fig. 3, but no numerical
data is presented here because of the low quality of the
determination which served mainly to confirm atom
connectivity and overall conformation.
Crystal data: C16H9MnN2O5, Mr=364.19, triclinic,
(
space group P1, a=9.677(2), b=11.55(1), c=17.53(3)
˚
A, h=71.45(3), i=94.65(2), k=88.08(3)°, V=1849(4)
A , Dcalc. =1.308 g cm−3, Z=4, F(000)=736, v(Mo–
3
˚
3. Results and discussion
Kh)=0.738 mm−1, Tmax 0.826, Tmin 0.706. Crystal size
0.70×0.28×0.21 mm3.
3.1. Syntheses
A total of 6054 (5670 unique) reflections were collected
at −143°C, 4°B2qB48°, 2186 with I\2|(I). The
structure solved to reveal two independent molecules of
the cyclomanganated diphenylnitrosamine. At this stage
significant residual electron density was found in the
Cyclomanganation of the mono- and di-phenylhydra-
zones of benzaldehyde and of acetophenone proceeds
smoothly under the normal conditions to give the C,N-
bonded five-membered ring metallocycles 3a–3d, Eq. 1:

130
M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
This reaction parallels those used by Sales et al. [30]
to prepare the mono- and di-manganated derivatives of
the di-azene of benzaldehyde, 3e and 3f.
Table 3
Atomic coordinates and equivalent isotropic displacement parameters
for
boylmanganese (4)
p2-2-(N2-cyclohexylidene-N1-phenylhydrazino)phenyltetracar-
Atom
x
y
z
U(eq)
Mn(1)
N(11)
N(12)
C(11)
C(12)
C(13)
C(14)
O(11)
O(12)
O(13)
0.6901(1)
0.8262(3)
0.8331(3)
0.5557(4)
0.5966(3)
0.7702(4)
0.7560(4)
0.4691(3)
0.5397(3)
0.8108(3)
0.7902(4)
0.6182(3)
0.7071(3)
0.6725(4)
0.5487(4)
0.4607(4)
0.4953(3)
0.9395(3)
1.0439(4)
1.1515(4)
1.1588(5)
1.0549(5)
0.9450(5)
0.8900(3)
0.9691(4)
0.9337(5)
0.9399(5)
0.8556(4)
0.8908(3)
0.9089(1)
0.7425(3)
0.6696(3)
1.0309(5)
0.9598(4)
0.8504(4)
1.0207(4)
1.1056(4)
1.0023(3)
0.8116(4)
1.0974(4)
0.7816(4)
0.6763(4)
0.5754(5)
0.5840(6)
0.6864(7)
0.7829(5)
0.6984(3)
0.6908(4)
0.7177(4)
0.7529(4)
0.7587(4)
0.7317(4)
0.6852(4)
0.5518(4)
0.4681(5)
0.5229(6)
0.6597(6)
0.7440(4)
0.2879(1)
0.2760(2)
0.3428(2)
0.3107(2)
0.2143(2)
0.3731(2)
0.2276(2)
0.3283(2)
0.1731(2)
0.4253(2)
0.1910(2)
0.3550(2)
0.3716(2)
0.4094(2)
0.4354(2)
0.4213(2)
0.3808(2)
0.3891(2)
0.3637(2)
0.4082(3)
0.4770(3)
0.5030(3)
0.4610(2)
0.2210(2)
0.2229(2)
0.1589(3)
0.0845(3)
0.0842(2)
0.1478(2)
0.8084(1)
0.7686(2)
0.8305(2)
0.8598(3)
0.8572(2)
0.7733(2)
0.7319(2)
0.8946(3)
0.8885(3)
0.7564(2)
0.6891(2)
0.8934(2)
0.8899(2)
0.9394(3)
0.9972(3)
1.0020(3)
0.9509(2)
0.8461(2)
0.9184(2)
0.9319(2)
0.8757(3)
0.8042(2)
0.7890(2)
0.7059(2)
0.6934(3)
0.6626(3)
0.5923(3)
0.6044(3)
0.6377(2)
0.3640(1)
0.2355(3)
0.1640(3)
0.4481(3)
0.2764(3)
0.4298(3)
0.4893(4)
0.4973(3)
0.2179(3)
0.4722(3)
0.5694(3)
0.2226(3)
0.1392(3)
0.0298(4)
0.0073(4)
0.0903(4)
0.1964(4)
0.1960(3)
0.2699(4)
0.2924(5)
0.2409(5)
0.1700(5)
0.1479(4)
0.1986(3)
0.0896(4)
0.0020(4)
0.0674(5)
0.1732(4)
0.2628(3)
0.3054(1)
0.2100(3)
0.1552(3)
0.3937(4)
0.1666(4)
0.4512(4)
0.2811(4)
0.4472(5)
0.0895(4)
0.5396(3)
0.2678(4)
0.3261(3)
0.2425(3)
0.2424(5)
0.3305(6)
0.4135(6)
0.4126(4)
0.0314(3)
0.033(1)
0.036(1)
0.042(1)
0.045(1)
0.038(1)
0.043(1)
0.046(1)
0.067(1)
0.063(1)
0.070(1)
0.072(1)
0.037(1)
0.040(1)
0.055(1)
0.058(1)
0.054(1)
0.045(1)
0.042(1)
0.053(1)
0.063(1)
0.068(1)
0.071(1)
0.057(1)
0.038(1)
0.050(1)
0.065(1)
0.068(1)
0.057(1)
0.043(1)
0.039(1)
0.037(1)
0.042(1)
0.062(1)
0.050(1)
0.049(1)
0.049(1)
0.102(2)
0.080(1)
0.072(1)
0.076(1)
0.046(1)
0.046(1)
0.063(1)
0.077(2)
0.077(2)
0.062(1)
0.040(1)
0.048(1)
0.054(1)
0.057(1)
0.052(1)
0.047(1)
0.044(1)
0.058(1)
0.069(1)
0.083(2)
0.083(2)
0.059(1)
O(14)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
C(131)
C(132)
C(133)
C(134)
C(135)
C(136)
Mn(2)
N(21)
N(22)
C(21)
Yields of 3a–3d are good and the compounds are
readily purified by chromatography. The compounds
are closely related to orthomanganated imines, first
reported by Bruce et al. [48], with a similar orthoman-
ganated ring [49,50]. There is no interference in the
reaction from the N–H group of the mono-phenylhy-
drazone reactions. One notable difference was that the
mono-phenylhydrazone examples 3a and 3b were in-
tensely orange while the di-phenylhydrazone examples
3c and 3d were light yellow, which is perhaps the
reverse of what would be expected. Possibly there is a
difference in the orientation of the N-bonded phenyl
rings in the two classes, limiting delocalisation in the
more crowded example.
With these substrates there is the possibility of differ-
ent isomers forming, 6a–e, depending on which N atom
coordinates to the manganese, and which aryl C–H
becomes the site of metallation.
C(22)
C(23)
C(24)
O(21)
O(22)
O(23)
O(24)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(221)
C(222)
C(223)
C(224)
C(225)
C(226)
C(231)
C(232)
C(233)
C(234)
C(235)
C(236)
−0.0141(4)
−0.1343(4)
−0.2087(4)
−0.1654(4)
−0.0452(4)
0.2050(4)
0.1490(4)
0.2442(5)
0.3020(6)
0.3555(6)
0.2632(5)

M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
131
Table 4
Selected bond parameters for p2-2-(N2-cyclohexylidene-N1-phenylhydrazino)phenyltetracarbonylmanganese (4)
Mol 1
Mol 2
Mol 1
Mol 2
˚
Bond lengths (A)
Mn–N(1)
Mn–C(1)
Mn–C(3)
N(1)–N(2)
N(2)–C(12)
2.096(3)
1.796(4)
1.862(4)
1.437(4)
1.429(5)
2.091(3)
1.798(4)
1.863(4)
1.453(4)
1.428(5)
Mn–C(11)
Mn–C(2)
Mn–C(4)
N(1)–C(31)
C(11)–C(12)
2.055(3)
1.865(4)
1.837(4)
1.278(5)
1.391(6)
2.056(4)
1.867(4)
1.842(4)
1.276(5)
1.380(6)
Bond angles (°)
C(11)–Mn–N(1)
Mn–N(1)–N(2)
N(2)–C(12)–C(11)
Mn–N(1)–C(31)
77.7(1)
110.3(2)
117.6(2)
134.1(2)
77.4(1)
C(2)–Mn–C(3)
169.6(2)
108.5(3)
113.0(2)
115.5(3)
171.7(2)
107.5(3)
112.9(4)
113.1(3)
109.7(2)
118.1(3)
134.2(3)
N(1)–N(2)–C(12)
Mn–C(11)–C(12)
N(1)–N(2)–C(21)
However only one isomer is observed in all of the
reactions, shown by an X-ray structure determination
of a representative example below to correspond to 6a.
It is generally accepted that five-membered metallo-
cyclic rings are most favoured so it is not surprising
that the six- or four-membered species 6d or 6e are
spurned. Compounds 6c and 6d would also only form
from the less-favoured anti isomer of the starting hy-
drazones which are only minor components in the
starting material. However isomer 6b includes a five-
membered ring and would form from the syn isomer of
the starting material so it would be a reasonable
product¸t¹o¹ºexpect. It appears that the more rigid,
would be interesting to investigate the phenylhydra-
zones of di-ortho-substituted acetophenones to see if
metallation of the N-bonded phenyl ring could be
directed when the alternative sites are blocked, a strat-
egy that has been successful for cyclopalladiation of the
phenylhydrazone of 2,4,6-trimethylbenzaldehyde [32].
To see whether a ring of the type shown in 6b could
be formed when there is no alternative, the orthoman-
ganation of the diphenylhydrazone of cyclohexanone
was examined. This too went smoothly (Eq. 2) to give
the exo complex 4 which indeed does incorporate the
¸¹¹º
novel MnC2N2 ring.
planar MnC3N ring of 6a is preferred to the alternative
¸¹¹º
MnC2N2 ring of 6b (these two alternatives have been
classified as endo and exo, respectively, in related palla-
dium examples [32]). Partial delocalisation of y-elec-
trons within the five-membered ring would be possible
for 6a but not for 6b, which may also be a factor. It
(2)
Fig. 2. The structure of the orthomanganated complex 4 derived from
the diphenylhydrazone of cyclohexanone. Only molecule 1 of the two
independent molecules is shown; the labelling for molecule 2 corre-
sponds directly, with N(11) becoming N(21), etc.
Fig. 3. The structure of the orthomanganated complex 5 derived from
diphenylnitrosamine.

132
M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
to significant differences in the w(CO) region, with the
two strongest peaks separated by 14 cm−1 (cf. 0–8
cm−1 in other derivatives) and with a particularly low
energy absorbance for the lowest frequency band at
1940 cm−1 (cf. \1945 cm−1 for others). Similarly the
1H- and 13C-NMR spectra were straightforward for all
of the compounds. The only example to be examined
by ESMS, the orthomanganated diphenylnitrosamine 5,
gave clear peaks assignable to [M+NH4]+ and [M+
H]+ ions under standard conditions.
This suggests that exo isomers of type 6b would be
stable if they were formed, but that the 6a type prod-
ucts are more favoured.
Finally Ph2NNO was examined to see if this could be
cyclometallated to give the corresponding ring to that
in 4, and this led to compound 5 in reasonable yield.
3.3. Structure determinations
The structure of the orthomanganated acetophe-
none–phenylhydrazone 3b is illustrated in Fig. 1. It
contains the expected five-membered ring with the man-
ganese attached to the ortho-position of the ring
derived from the acetophenone moiety and to the CꢀN
nitrogen atom. The coordination about the manganese
atom is essentially octahedral, with the main deviation
associated with the C(11)–Mn–N(1) bite angle of
78.5°. The core of the molecule is planar, with the
anilino–aryl group twisted to generate a dihedral angle
of 77°. The metallocyclic ring is directly analogous to
those characterised previously in derivatives of the
phenylimines of benzaldehyde [53] and 2-chloroace-
tophenone [49], and in the di-azine species 3e and 3f
[30]. The geometry of the corresponding part of the
molecules in all these species shows little variation.
The structure analysis of the orthomanganated com-
plex derived from the cyclohexanone–diphenylhydra-
zone, 4, revealed two independent molecules in the
asymmetric unit. These differed mainly in the relative
orientation of the non-coordinated phenyl ring which
gave dihedral angles with respect to the chelate ring of
54 and 70°, respectively, in the two molecules. Fig. 2
Again this is a new type of orthomanganated com-
plex, although analogous Pd species have been pre-
pared
from
N-methyl-N-nitrosoanilines
[51,52].
Characterisation of 5 was made more difficult by co-
crystallisation with an impurity. 13C-NMR spec-
troscopy of a sample of 5 after chromatography and
recrystallisation showed extra peaks which exactly coin-
cided with those of a genuine sample of Ph2NH, and
the presence of this species is consistent with microana-
lytical data, with the ESMS data (where a Ph2NH2+ ion
was identified) and with the crystal structure determina-
tion where residual electron density associated with
phenyl rings was found. There was no Ph2NH in the
starting nitrosamine so it appears that some of the
Ph2NNO is converted to Ph2NH during the orthometal-
lation procedure. Although there is no doubt that com-
pound 5 was synthesised, leading to an alternative
¸¹¹º
example containing a MnC2N2 ring, we cannot claim to
have isolated a pure sample and propose that some
Ph2NH formed during the reaction was not separated
shows the geometry of molecule 1, which does contain
¸¹¹º
from
5
either by chromatography or by
the unique MnC2N2 ring. In contrast to other or-
thomanganated species, this ring is not planar, but is
recrystallisation.
Overall, however, phenylhydrazones and related spe-
cies are therefore good substrates for orthomangana-
˚
puckered so that N(12) is 0.23 A above, and N(11) 0.24
˚
¸¹¹º
¸¹¹º
A below, the least squares plane of the ring. This is
tion reactions, giving either MnC3N or MnC2N2 rings,
depending on the substituents. The compounds are all
reasonably stable and can be handled in air without
significant decomposition. Indeed the orthomanganated
primary phenylhydrazones 3a and 3c appear to be less
susceptible to autoxidation via the N–H bond than the
non-metallated precursors.
presumably to accommodate the sp3 hybridised N(12),
which precludes delocalisation of electron density
within the metallocyclic unit. Consistent with this, the
Mn–N and N–N bonds are longer than those in the
imine-derived metallocyclic ring of 3b. In the analogous
¸¹¹º
PdC2N2 species the ring is much closer to planar with
shorter N–N distances [32].
The crystal structure of the orthomanganated
diphenylnitrosamine 5 was also determined. Only
weakly diffracting crystals could be formed, and a
co-crystallising impurity complicated analysis, so that
the results can only be used to confirm the overall
conformation of the compound. Clearly cyclometalla-
3.2. Spectroscopy
The new compounds gave the expected spectroscopic
features. The carbonyl-region IR spectra showed the
normal four-band pattern characteristic of the cis
L2Mn(CO)4 group, although accidental degeneracy of
the middle two bands occurred for compound 3c. The
different type of metallocyclic ring in complex 4 leads
tion has occurred to give another example of the
¸¹¹º
MnC2N2 ring found for compound 4. Here the ring

M.B. Dinger et al. / Journal of Organometallic Chemistry 565 (1998) 125–134
133
Scheme 1.
appears to be planar, with shorter Mn–N and N–N
bonds than for 4, but this may be an artifact of the
imprecise determination so is not discussed further,
other than to note that the same general features were
found in the cyclopalladiated N-nitroso examples
[51,52].
with orthometallated triphenylphosphite [57] or
triphenylphosphine sulphide [58]. The second step will
be intra-molecular addition of the new Mn–C bond
across the CꢀN group to form the indene core (II) with
the Mn group associated as the unidentified Mn(CO)3
species detected by IR. This species presumably
achieves an 18-e configuration by coordination of
MeCN solvent molecules, since removal of solvent led
to decomposition; alternatively intramolecular coordi-
nation to electron density from the indene ring would
be possible. Protio-demetallation on work-up would
lead to the final highly-substituted hydrazine products 7
or 8 (Scheme 1).
In contrast, reactions of the mono-phenylhydrazone
complexes 3a or 3b with alkynes did not lead to charac-
terised products. Reaction did take place under similar
conditions but work-up yielded a multitude of species
in low yields and so they were not further investigated.
Similarly, no major products were found with the cyclo-
hexylidene complex 4.
3.4. Reactions of orthomanganated hydrazones with
alkynes
When the diphenylhydrazone complexes 3c or 3d
were reacted with the alkynes Ph2C2 or Me3SiC2H the
indenyl hydrazines 7a–c or 8a,b were isolated in moder-
ate yields after chromatography on alumina.
These preliminary investigations into the coupling
reactions of the hydrazone complexes therefore show
that there are some similarities with the established
chemistry for analogous ketone complexes, but they
appear to be less generally useful.
Conditions used were reflux in acetonitrile for 2–5 h,
since preliminary studies showed this solvent resulted in
a cleaner reaction than benzene or heptane. At comple-
tion of the reaction, an infrared spectrum of the mix-
ture showed w(CO) bands with a distinctive pattern
associated with a fac-LMn(CO)3 fragment. However
this proved to be too unstable to characterise and
work-up provided only metal-free products, with the
indenyl hydrazines the only ones in significant amounts.
Compounds 7 and 8 are the expected products by
analogy with the reactions of orthomanganated aryl
ketones with alkynes [9,54–56], and a similar mecha-
nism can be proposed. The first step will be insertion of
the alkyne into the Mn–C bond of the complex 3 to
give a seven-membered ring species (I); related species
have been characterised from the equivalent reactions
Acknowledgements
We thank Professor Ward Robinson, University of
Canterbury, and Associate Professor Cliff Rickard,
University of Auckland, for collection of X-ray inten-
sity data. Financial support from the University of
Waikato, and from the New Zealand Lotteries Board is
gratefully acknowledged.
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