Orthomanganation of the iminophosphorane Ph3P=NPh, and of triphenylarsine-oxide and -sulfide

Article abstract of DOI:10.1016/S0022-328X(99)00007-8

Two novel types of cyclometallated rings are described. Orthomanganation of Ph₃P=NPh gave Ph₂P[=NPh]C₆H₄Mn(CO)₄, 5a, containing an N,C-chelated five-membered ring, characterised by single crystal X-ray determinations of two distinct polymorphs. Solutions of 5a are thermochroic. The rhenium analogue of 5a was also prepared. Reaction of Ph₃As=X (X=O, S) with PhCH₂Mn(CO)₅ gave the first examples of orthometallated triphenylarsine chalcogenides. The example with X=O was characterised structurally. Attempted cyclomanganation of Ph₃As was unsuccessful, but gave (in low yield) a dimanganese complex containing μ-AsPh₂ and μ-η¹,η⁶-benzyl ligands.

Full text of DOI:10.1016/S0022-328X(99)00007-8

Journal of Organometallic Chemistry 579 (1999) 243–251
Orthomanganation of the iminophosphorane Ph3PꢀNPh, and of
triphenylarsine-oxide and -sulfide
Mark A. Leeson, Brian K. Nicholson *, Mark R. Olsen
Department of Chemistry, Uni6ersity of Waikato, Pri6ate Bag 3105, Hamilton, New Zealand
Received 27 November 1998
Abstract
¸¹¹¹¹¹º
Two novel types of cyclometallated rings are described. Orthomanganation of Ph3PꢀNPh gave Ph2P[ꢀNPh]C6H4Mn(CO)4, 5a,
containing an N,C-chelated five-membered ring, characterised by single crystal X-ray determinations of two distinct polymorphs.
Solutions of 5a are thermochroic. The rhenium analogue of 5a was also prepared. Reaction of Ph3AsꢀX (XꢀO, S) with
PhCH2Mn(CO)5 gave the first examples of orthometallated triphenylarsine chalcogenides. The example with XꢀO was character-
ised structurally. Attempted cyclomanganation of Ph3As was unsuccessful, but gave (in low yield) a dimanganese complex
containing m-AsPh2 and m–h1,h6-benzyl ligands. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Orthometallation; Manganese; Iminophosphorane; Triphenylarsine oxide; Triphenylarsinesulfide
1. Introduction
(XꢀO, S, Se) which gave stable derivatives 4 which
showed interesting reactivity at the Mn–Caryl bond
[10,11].
Cyclometallation reactions involving manganese are
now second only to those of palladium in the amount of
study devoted to them. Reaction of RMn(CO)5 with a
whole range of O-, N-, S- and P-donor aryl substrates
gives stable derivatives of the type 1, usually with a
five-membered ring [1–3]. The manganese compounds
derived from aromatic ketones are especially well-stud-
ied and have been shown to be of use in organic synthesis
[1,4–6].
The present paper extends this previous work in two
ways. Firstly we report the successful cyclometallation of
the iminophosphorane Ph3PꢀNPh, an example from a
class of compound electronically analogous to the phos-
phine chalcogenides. Secondly, we describe the corre-
sponding reactions of the triphenylarsenic oxide and
sulfide, which also appear not to have been examined
under cyclometallation conditions before.
The cyclomanganation chemistry of phosphines has a
long history. Kaesz%s group [7] first showed that PPh3
gave rise to the four-membered ring compound 2 to-
gether with other products arising from secondary reac-
tions of 2. Reaction with (PhO)3P was more predictable,
leading to good yields of the five-membered ring com-
pound 3 [8]. The reactivity of 3 towards insertion
reactions with alkynes has been studied in detail [9].
More recently we extended this work to the orthoman-
ganation of triphenylphosphine chalcogenides Ph3PꢀX,
* Corresponding author. Fax: +64-7-838-4219.
E-mail address: b.nicholson@waikato.ac.nz (B.K. Nicholson)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00007-8

244
M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
2.3.2. Reaction of Ph3PꢀNPh with PhCH2Re(CO)5
2. Experimental
2.1. General
Similarly Ph3PꢀNPh (0.291 g, 0.83 mmol),
PhCH2Re(CO)5 (0.345 g, 0.83 mmol) and petroleum
spirits (100–130°C fraction, 40 ml) were heated under
reflux until the 2127 cm−1 band of the starting material
had disappeared (about 2 h). The solvent was evapo-
rated under vacuum to about half volume and cooled
to precipitate as a pale yellow powder the product 5b
All manipulations were carried out in an oxygen-free
N2 atmosphere with dried solvents in Schlenk equip-
ment. PhCH2Mn(CO)5 was prepared by the standard
method [12], and PhCH2Re(CO)5 analogously.
Ph3PꢀNPh was produced from Ph3P and PhN3, using
the Staudinger reaction [13]. Ph3AsꢀO (m.p. 192–
195°C, lit. 189°C) was from H2O2-oxidation of Ph3As,
while the corresponding sulfide was from Ph3AsꢀO and
CS2 (m.p. 167–168°C, lit. 167–168°C) [14].
(0.425 g, 88%). IR w(CO): (petroleum spirits, cm−1
)
2083 (m), 2015 (s), 1970 (vs), 1925(s). NMR (l CDCl3):
1H-NMR, 8.27–8.22, 7.72–7.58, 7.54–7.37, 7.21–7.12,
6.99–6.91 (all m, Ar–H); 13C, 192.34 (s, CO), 192.11 (d,
Jpc=4.6 Hz, CO), 190.76 (s, 2CO), 169.36 (d, Jpc=26.1
Hz, Re–C), 151.52 (d, Jpc=2.0 Hz), 144.06 (d, Jpc=
16.2 Hz), 141.22 (d, Jpc=132.1 Hz), 133.39 (d, Jpc=9.6
Hz), 133.49 (d, Jpc=2.0 Hz), 132.86 (d, Jpc=1.9 Hz),
131.04 (d, Jpc=2.6 Hz), 129.20 (d, Jpc=43.2 Hz),
129.03 (d, Jpc=11.8 Hz), 128.74 (s), 128.23 (d, Jpc=6.2
Hz), 123.89 (d, Jpc=14.4 Hz), 123.27 (Jpc=1.5Hz);
31P-NMR, 50.6. ESMS (MeOH with NaOMe) m/z 682
[M+OMe]−, 654 [M+OMe–CO]−.
2.2. Instrumentation
Infrared spectra were recorded on a Digilab FTS-40
FTIR spectrophotometer. NMR spectroscopy was per-
formed using a Bruker AC300P Multinuclear FT spec-
trometer. Electrospray mass spectra were collected
using a VG Platform II instrument, usually in MeOH
with added NaOMe for derivatisation [15]. Elemental
analysis was performed by the Campbell Microanalyti-
cal Laboratory, University of Otago.
2.3.3. Reaction of Ph3AsꢀO with PhCH2Mn(CO)5
Ph3AsꢀO (0.353 g, 1.095 mmol), PhCH2Mn(CO)5
(0.393 g, 1.37 mmol) and hexane (45 ml) were heated
under reflux for 2h by which time an IR spectrum
showed the 2107 cm−1 band of the starting material
had disappeared. The solvent was evaporated under
vacuum to about half volume and the solution was left
at 0°C to give yellow crystals of orthomanganated
Ph3AsꢀO, 6a (0.182 g, 34%). IR w(CO): (petroleum
spirits, cm−1) 2075 (m), 1988 (vs, br), 1929(s). ESMS
(MeOH with NaOMe) m/z 519 [M+OMe]−. The
compound was characterised fully by an X-ray crystal
structure determination (see below).
2.3. Reactions
2.3.1. Reaction of Ph3PꢀNPh with PhCH2Mn(CO)5
To a Schlenk flask was added Ph3PꢀNPh (0.300 g,
0.85 mmol), PhCH2Mn(CO)5 (0.283 g, 0.99 mmol) and
heptane (35 ml), and the mixture was heated under
reflux for 2 h. The solution became an intense purple
colour, which changed to golden yellow on cooling. An
IR spectrum showed the 2107 cm−1 band of the start-
ing material had disappeared. The solvent was evapo-
rated under vacuum to about a quarter volume and the
solution was left at 0°C to give yellow crystals of the
product 5a (0.283 g, 64%). Found C 64.76, H 3.62, N
2.89%; C28H19PNO4Mn requires C 64.75, H 3.69, N
2.70%. IR w(CO): (petroleum spirits, cm−1) 2069 (m),
1982 (vs, br), 1927(s). Raman (solid, cm−1) w(CO):
2073(m), 2066(m), 1972(s), 1967(s), 1917(m) 1908(m).
NMR (l CDCl3): 1H-NMR, 8.09–8.06, 7.59–7.30,
7.09–7.04, 6.93–6.82 (all m, Ar–H); 13C-NMR, 220.36
(s, CO), 215.17 (s, 2CO), 213.65 (s, CO), 180.62 (d,
Jpc=25.6 Hz, Mn–C), 151.56 (s), 142.63 (d, Jpc=16.0
Hz), 139.61 (d, Jpc=135.5 Hz), 133.18 (d, Jpc=9.7
Hz), 138.49 (d, Jpc=2.0 Hz), 130.79 (d, Jpc=22.4 Hz),
130.76 (d, Jpc=3.0 Hz), 129.61 (d, Jpc=2.0 Hz), 129–
128 (m), 123.58 (d, Jpc=14.2 Hz), 122.90 (d, Jpc=2.0
Hz); 31P-NMR, 44.3. ESMS (MeOH with NaOMe) m/z
550 [M+OMe]−, 522 [M+OMe–CO]−. The com-
pound was fully characterised by X-ray crystal struc-
ture determinations on two different crystal forms (see
below).
2.3.4. Reaction of Ph3AsꢀS with PhCH2Mn(CO)5
A directly analogous procedure with Ph3AsꢀS (0.135
g, 0.40 mmol), PhCH2Mn(CO)5 (0.123 g, 0.43 mmol)
and hexane (40 ml) for 2.5 h gave yellow/orange crys-
tals of orthomanganated Ph3AsꢀS, 6b (0.045 g, 22%).
IR w(CO): (petroleum spirits, cm−1) 2070 (m), 1984 (vs,
br), 1927(s). ESMS (MeOH with NaOMe) m/z 535
[M+OMe]−.
2.3.5. Reaction of Ph3As with PhCH2Mn(CO)5
Ph3As (0.100 g, 0.33 mmol) and PhCH2Mn(CO)5
(0.085 g, 0.30 mmol) were added to heptane (30 ml),
and the mixture was heated under reflux for 2.5 h. A
preliminary TLC indicated that at least 10 compounds
were present, all in rather small amounts. A preparative
scale separation on a silica plate gave incomplete reso-
lution and only three compounds could be isolated in
low yield and identified:

M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
Table 1 (Continued)
245
Table 1
Refined parameters for the structure of the C2/c form of orthoman-
ganated Ph3PꢀNPh, 5a
Atom
x
y
z
Ueq
Atom
x
y
z
Ueq
C(234)
C(235)
C(236)
C(241)
C(242)
C(243)
C(244)
C(245)
C(246)
0.0098(1)
0.0294(1)
0.0564(1)
0.1026(1)
0.0660(1)
0.0656(1)
0.1025(2)
0.1389(1)
0.1405(1)
0.7386(4)
0.6421(4)
0.5530(4)
0.4667(4)
0.4415(4)
0.4503(4)
0.4840(4)
0.5080(4)
0.5015(4)
0.1557(2)
0.1508(2)
0.1973(2)
0.3705(2)
0.3576(2)
0.4022(2)
0.4601(2)
0.4733(2)
0.4288(2)
0.034(1)
0.041(1)
0.039(1)
0.026(1)
0.033(1)
0.037(1)
0.040(1)
0.032(1)
0.028(1)
Mn(1)
P(1)
N(1)
C(11)
C(12)
C(13)
C(14)
O(11)
O(12)
0.0991(1)
0.1427(1)
0.1111(1)
0.1435(2)
0.0590(2)
0.0921(1)
0.0640(1)
0.1734(1)
0.0338(1)
0.0879(1)
0.0438(1)
0.0851(1)
0.0956(2)
0.0693(2)
0.0324(2)
0.0217(2)
0.0476(1)
0.1181(1)
0.1115(1)
0.0914(1)
0.0786(1)
0.0843(1)
0.1039(1)
0.1833(1)
0.1977(1)
0.2297(1)
0.2480(1)
0.2351(1)
0.2029(1)
0.1657(1)
0.1994(1)
0.2147(1)
0.1959(2)
0.1629(1)
0.1461(1)
0.1934(1)
0.1045(1)
0.1511(1)
0.1781(1)
0.2376(1)
0.2278(1)
0.2001(1)
0.1683(1)
0.2667(1)
0.2504(1)
0.2029(1)
0.1616(1)
0.1512(2)
0.1623(2)
0.1840(2)
0.1950(2)
0.1835(1)
0.0925(1)
0.0520(1)
0.0448(2)
0.0776(1)
0.1176(2)
0.1248(2)
0.0644(1)
0.0447(1)
0.0172(1)
0.1028(1)
0.1061(1)
0.0642(1)
0.0723(1)
0.1819(2)
0.0938(2)
0.1373(2)
0.0325(2)
0.2296(2)
0.0874(2)
0.1577(2)
0.030(1)
0.026(1)
0.026(1)
0.042(1)
0.043(1)
0.040(1)
0.037(1)
0.077(1)
0.060(1)
0.064(1)
0.060(1)
0.027(1)
0.046(1)
0.062(2)
0.059(2)
0.053(2)
0.039(1)
0.027(1)
0.031(1)
0.040(1)
0.041(1)
0.040(1)
0.036(1)
0.025(1)
0.032(1)
0.043(1)
0.045(1)
0.044(1)
0.034(1)
0.026(1)
0.034(1)
0.042(1)
0.045(1)
0.038(1)
0.026(1)
0.031(1)
0.026(1)
0.026(1)
0.038(1)
0.036(1)
0.038(1)
0.037(1)
0.061(1)
0.054(1)
0.060(1)
0.055(1)
0.030(1)
0.054(2)
0.082(2)
0.067(2)
0.055(2)
0.039(1)
0.030(1)
0.043(1)
0.055(2)
0.055(2)
0.052(1)
0.042(1)
0.027(1)
0.030(1)
0.034(1)
−0.0159(1)
−0.0493(3)
0.0408(4)
0.0030(5)
0.2339(5)
0.1899(5)
0.0081(3)
−0.0557(3)
0.3207(4)
0.2532(3)
−0.1653(4)
−0.2779(5)
−0.3878(5)
−0.3849(5)
−0.2737(6)
−0.1633(5)
0.0065(4)
0.1324(4)
0.1536(4)
0.0468(5)
−0.0802(5)
−0.1006(4)
−0.1393(4)
−0.1794(4)
−0.2710(4)
−0.3199(4)
−0.2782(5)
−0.1879(4)
0.1372(4)
0.1915(4)
0.3146(5)
0.3814(5)
0.3261(4)
0.2018(4)
0.5334(1)
0.4586(1)
0.5050(3)
0.7110(5)
0.5550(5)
0.5637(4)
0.3529(5)
0.8198(3)
0.5685(3)
0.5827(4)
0.2405(3)
0.5444(4)
0.6699(5)
0.7088(6)
0.6262(7)
0.5038(6)
0.4626(5)
0.2932(4)
0.2490(5)
0.1201(5)
0.0360(5)
0.0779(5)
0.2054(4)
0.5615(4)
0.6603(4)
0.7473(4)
O(13)
O(14)
1. From the fastest moving yellow band was isolated
some orthomanganated Ph3AsꢀO, 6a, identified by
comparison with an authentic sample.
−0.0104(2)
0.0446(2)
0.0776(2)
0.0518(3)
−0.0081(3)
−0.0414(2)
−0.0157(2)
−0.0131(2)
−0.0356(2)
−0.0952(2)
−0.1325(2)
−0.1116(2)
−0.0522(2)
0.0972(2)
0.0707(2)
0.0993(2)
0.1550(2)
0.1829(2)
0.1541(2)
0.1033(2)
0.1142(2)
0.1416(2)
0.1570(2)
0.1469(2)
0.1195(2)
0.4430(1)
0.3140(1)
0.3490(1)
0.4250(2)
0.4494(2)
0.5225(2)
0.4558(2)
0.4131(2)
0.4565(1)
0.5736(1)
0.4635(1)
0.3155(2)
0.2906(2)
0.2597(3)
0.2541(2)
0.2795(2)
0.3099(2)
0.2829(2)
0.2354(2)
0.2132(2)
0.2382(2)
0.2852(2)
0.3076(2)
0.2503/2)
0.2549(2)
0.2077(2)
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)
C(141)
C(142)
C(143)
C(144)
C(145)
C(146)
Mn(2)
P(2)
2. From a second yellow band was crystallised cis-
PhCH2Mn(CO)4(AsPh3), m.p. 130°C, IR w(CO):
(petroleum spirits, cm−1) 2055 (m), 1980 (m),
1969(s), 1938 (m). The compound was characterised
by an X-ray crystal structure determination on a
poor quality crystal (final R1 0.12). The result confi-
rmed the identity and overall geometry of the com-
pound but the accuracy of the determination does
not merit further discussion.
3. From a slower moving orange band was isolated a
red crystalline product identified as (m–h1,h6-
C6H5CH2)(m-AsPh2)Mn2(CO)6, 7, IR w(CO): (cm−1
)
2066 (m), 2018 (m), 1990 (m), 1979(s), 1949 (s).
ESMS (MeOH with NaOMe) m/z 629 [M+
OMe]−. Full characterisation was by a single crystal
X-ray determination (see below).
In an attempt to improve the specificity of the reaction,
PhCH2Mn(CO)4(AsPh3) was prepared separately using
[Mn(CO)4(AsPh3)]− (from Mn2(CO)8(AsPh3)2 and Na/
Hg amalgam) with PhCH2Br, and this was then py-
rolysed in refluxing heptane. Again a plethora of
products resulted so the reaction was not investigated
further.
N(2)
C(21)
C(22)
C(23)
C(24)
O(21)
O(22)
O(23)
2.4. X-ray crystallography
For the structure determinations of the Cc form of
5a, and for 7, unit cell parameters and intensity data
were collected using a Siemens SMART CCD diffrac-
tometer, using standard collection procedures, with
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)
˚
monochromatic Mo–Ka X-rays (0.71073 A). Correc-
tions for absorption and other effects were carried out
with SADABS [16]. For the C2/c version of 5a and for 6a
data was collected on a Siemens P4 four-circle diffrac-
tometer using v-scans, and was corrected for absorp-
tion using a F-scan method. Calculations used the
SHELX97 programs [17]. The structures were solved by
direct methods, and developed routinely with refine-
ment based on F2. All non-hydrogen atoms were as-
signed anisotropic temperature factors, and hydrogen
atoms were included in calculated positions.

246
M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
Table 2
A total of 7059 reflections, 5350 unique (Rint 0.0471)
was collected 2°BqB26°. Final R1 0.0596 (3753 data
with I=2|(I)), 0.0806 (all data), wR2 0.1061, GoF
1.221, final De +0.324. The penultimate refinement
cycles suggested racemic twinning, which was included
in the final refinement leading to a Flack x parameter
of 0.225(35) [17]. Refined coordinates are in Table 2,
and selected bond parameters in Table 5.
Refined parameters for the structure of the Cc form of orthoman-
ganated Ph3PꢀNPh, 5a
Atom
x
y
z
Ueq
Mn(1)
P(1)
N(1)
C(1)
C(2)
C(3)
C(4)
O(1)
O(2)
0.8493(1)
0.8428(1)
0.8831(3)
0.9391(5)
0.9116(4)
0.8140(4)
0.7548(4)
0.9932(3)
0.9523(3)
0.7876(3)
0.6966(3)
0.9291(3)
1.0124(3)
1.0584(3)
1.0227(4)
0.9389(4)
0.8930(3)
0.7670(4)
0.7883(4)
0.7303(4)
0.6514(4)
0.6294(4)
0.6858(3)
0.9175(3)
0.9780(4)
1.0381(4)
1.0388(4)
0.9798(4)
0.9195(4)
0.7944(3)
0.7621(3)
0.7220(4)
0.7173(4)
0.7503(3)
0.7908(3)
0.1273(1)
0.3191(1)
0.2436(3)
0.1311(4)
0.0778(4)
0.0312(4)
0.1373(4)
0.1379(3)
0.0446(3)
0.9113(1)
0.9002(2)
0.9900(5)
0.8062(8)
1.0650(7)
0.8409(7)
1.0012(7)
0.7399(6)
1.1570(5)
0.7950(5)
1.0532(5)
1.1318(6)
1.1473(6)
1.2841(6)
1.4085(6)
1.3951(6)
1.2588(5)
0.9891(6)
1.1268(6)
1.1961(6)
1.1305(7)
0.9932(7)
0.9214(6)
0.8585(6)
0.7772(7)
0.7428(7)
0.7877(7)
0.8688(7)
0.9050(6)
0.7331(6)
0.6147(6)
0.4886(6)
0.4866(6)
0.6027(6)
0.7332(6)
0.032(1)
0.027(1)
0.027(1)
0.043(2)
0.043(2)
0.046(2)
0.036(2)
0.068(2)
0.063(1)
0.071(2)
0.062(2)
0.030(1)
0.034(1)
0.040(2)
0.043(2)
0.045(2)
0.036(1)
0.028(1)
0.039(2)
0.043(2)
0.042(2)
0.045(2)
0.033(1)
0.026(1)
0.047(2)
0.053(2)
0.052(2)
0.053(2)
0.042(2)
0.029(1)
0.038(1)
0.048(2)
0.047(2)
0.041(2)
0.030(1)
2.4.3. Crystal data for orthomanganated Ph3AsꢀO, 6a
C22H14AsMnO5, Mr 488.19, monoclinic, P21/n, a=
˚
11.307(1), b=14.460(2), c=13.564(2) A, i=110.23(1),
3
˚
V=2080.9(5) A ,
D
calc=1.558
g
cm−3
,
Z=4,
O(3)
O(4)
−0.0291(3)
0.1448(4)
0.2529(3)
0.2727(3)
0.2754(4)
0.2586(4)
0.2399(4)
0.2368(4)
0.3744(3)
0.4067(3)
0.4479(4)
0.4562(4)
0.4249(4)
0.3828(3)
0.3932(3)
0.3671(4)
0.4202(5)
0.4981(4)
0.5253(4)
0.4724(4)
0.2746(4)
0.3224(4)
0.2862(4)
0.2025(4)
0.1568(4)
0.1902(3)
F(000)=976, v(Mo–Ka) 2.242 mm−1, Tmax 0.823, T
min
0.743, crystal size 0.88×0.72×0.64 mm3, T 169 K.
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
A total of 3712 reflections, 3636 unique (Rint 0.0252)
was collected 2°BqB25°. Final R1 0.0283 (2670 data
with I=2|(I)), 0.0446 (all data), wR2 0.0532, GoF
1.015, final De −0.297. Refined coordinates are in
Table 3, and selected bond parameters are in the cap-
tion to Fig. 2.
2.4.4. Crystal data for (v–p1,p6-C6H5CH2)(v-AsPh2)-
Mn2(CO)6,
7
C25H17AsMn2O6, Mr 598.19, monoclinic, P21/n, a=
Table 3
Refined parameters for the structure of orthomanganated Ph3AsꢀO,
6a
Atom
x
y
z
Ueq
As(1)
Mn(1)
C(1)
O(1)
C(2)
O(3)
C(3)
O(2)
C(4)
0.1857(1)
0.0070(1)
0.1510(3)
0.2376(2)
0.3462(1)
0.1845(1)
0.1349(2)
0.1073(2)
0.0875(2)
0.0957(2)
0.1303(2)
0.0256(2)
0.2531(2)
0.2975(2)
0.2498(1)
0.3664(2)
0.2967(2)
0.3091(2)
0.3837(2)
0.4510(2)
0.4423(2)
0.3300(2)
0.3100(2)
0.2954(2)
0.3022(2)
0.3222(2)
0.3366(2)
0.4440(2)
0.4417(2)
0.5133(2)
0.5844(2)
0.5866(2)
0.5163(2)
0.3732(1)
0.3976(1)
0.4936(3)
0.5574(2)
0.3048(3)
0.5081(2)
0.4637(3)
0.2500(2)
0.3182(2)
0.2721(2)
0.3156(1)
0.4876(2)
0.4999(2)
0.5865(2)
0.6528(3)
0.6370(3)
0.5539(2)
0.4211(2)
0.5255(2)
0.5584(3)
0.4882(3)
0.3849(3)
0.3506(2)
0.2725(2)
0.1926(2)
0.1208(2)
0.1274(2)
0.2070(2)
0.2802(2)
0.024(1)
0.028(1)
0.036(1)
0.062(1)
0.039(1)
0.069(1)
0.044(1)
0.065(1)
0.034(1)
0.056(1)
0.027(1)
0.025(1)
0.027(1)
0.034(1)
0.042(1)
0.042(1)
0.034(1)
0.027(1)
0.033(1)
0.046(1)
0.052(1)
0.053(1)
0.037(1)
0.023(1)
0.026(1)
0.031(1)
0.034(1)
0.035(1)
0.032(1)
−0.0195(3)
−0.1434(2)
−0.0851(3)
−0.0359(2)
−0.1314(3)
−0.2153(2)
0.1089(2)
0.1305(2)
0.0510(3)
0.0119(3)
0.0489(3)
0.1262(3)
0.1683(3)
0.3646(2)
0.4300(3)
0.5580(3)
0.6209(3)
0.5569(3)
0.4289(3)
0.1455(3)
0.0297(3)
−0.0043(3)
0.0788(3)
0.1945(3)
0.2285(3)
2.4.1. Crystal data for the C2/c form of
cyclomanganated Ph3PꢀNPh, 5a
C28H19MnNO4P, Mr 519.35, monoclinic, C2/c, a=
44.03(3), b=10.093(7), c=30.50(2) A, i=133.47(2),
V=9835(11) A ,
˚
O(4)
3
D
calc=1.403
g
cm−3
,
Z=16,
˚
O(11)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
F(000)=4256, v(Mo–Ka) 0.637 mm−1, Tmax 0.823,
Tmin 0.743, crystal size 0.6×0.4×0.2 mm3, T 173 K.
A total of 9182 reflections, 6990 unique (Rint 0.0395)
was collected 2°BuB24°. Final R1 0.0482 (4326 data
with I=2|(I)), 0.1023 (all data), wR2 0.0931, GoF
1.042, final De +0.301. Refined coordinates are in
Table 1, and selected bond parameters in Table 5.
2.4.2. Crystal data for the Cc form of cyclomanganated
Ph3PꢀNPh, 5a
C28H19MnNO4P, Mr 519.35, monoclinic, Cc, a=
˚
16.3218(5), b=16.5622(5), c=9.1942(1) A, i=
97.3780(1), V=2464.8(1) A , Dcalc=1.400 g cm−3
,
3
˚
Z=4, F(000)=1064, v(Mo–Ka) 0.635 mm−1, Tmax
1.162, Tmin 0.729, crystal size 0.2×0.2×0.2 mm3, T
203 K.

M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
247
Table 4
Refined parameters for the structure of (m–h1,h6-C6H5CH2)(m-
AsPh2)Mn2(CO)6, 7
Atom
x
y
z
Ueq
As(1)
Mn(1)
Mn(2)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(11)
C(12)
C(13)
C(14)
O(11)
O(12)
O(13)
O(14)
C(21)
C(22)
O(21)
O(22)
C(1)
0.2608(1)
0.3436(1)
0.3768(1)
0.2404(1)
0.1643(2)
0.1528(2)
0.2171(2)
0.2916(2)
0.3033(2)
0.0915(1)
0.0393(2)
−0.0795(2)
−0.1467(2)
−0.0962(2)
0.0225(2)
0.2014(2)
0.3873(2)
0.4182(2)
0.3126(2)
0.1122(1)
0.4155(2)
0.4677(1)
0.2928(1)
0.2860(2)
0.2720(2)
0.2258(1)
0.2061(1)
0.5180(2)
0.5212(1)
0.5290(1)
0.5380(1)
0.5329(2)
0.5191(2)
0.5143(1)
0.1299(1)
0.0291(1)
0.2396(1)
0.0993(1)
0.0408(1)
0.0139(1)
0.0451(1)
0.1038(1)
0.1309(1)
0.1496(1)
0.1295(1)
0.1467(1)
0.1850(1)
0.2050(1)
0.1872(1)
−0.0179(1)
−0.0158(1)
−0.0418(1)
0.0859(1)
−0.0488(1)
−0.0447(1)
−0.0865(1)
0.1219(1)
0.2826(1)
0.2724(1)
0.3116(1)
0.2953(1)
0.0835(1)
0.1602(1)
0.1772(1)
0.2494(1)
0.3079(1)
0.2926(1)
0.2194(1)
0.6648(1)
0.7809(1)
0.6846(1)
0.5046(1)
0.4803(2)
0.3700(2)
0.2831(2)
0.3048(2)
0.4162(1)
0.6954(1)
0.7977(2)
0.8194(2)
0.7399(2)
0.6379(2)
0.6156(2)
0.7825(2)
0.6474(2)
0.8631(2)
0.9073(2)
0.7832(2)
0.5662(1)
0.9127(1)
0.9842(1)
0.5775(2)
0.7875(2)
0.5109(1)
0.8528(1)
0.7792(2)
0.7402(1)
0.6216(1)
0.5834(2)
0.6615(2)
0.7773(2)
0.8163(2)
0.021(1)
0.026(1)
0.023(1)
0.026(1)
0.036(1)
0.044(1)
0.042(1)
0.039(1)
0.031(1)
0.026(1)
0.033(1)
0.043(1)
0.059(1)
0.054(1)
0.041(1)
0.038(1)
0.035(1)
0.039(1)
0.036(1)
0.065(1)
0.060(1)
0.061(1)
0.056(1)
0.031(1)
0.033(1)
0.048(1)
0.054(1)
0.034(1)
0.027(1)
0.030(1)
0.034(1)
0.036(1)
0.036(1)
0.031(1)
(1)
The new complex 5a does not survive chromatography
on silica but it could be readily purified by crystallisa-
tion, giving reasonably air-stable yellow crystals. As far
as we are aware, this is the first example of a or-
thometallated iminophosphorane, giving a novel metal-
locyclic ring. The closest analogue appears to be a
cyclic zirconium phosphazene [18] involving a non-aro-
matic ligand.
Surprisingly, compound 5a is thermochromic in solu-
tion. When heptane or toluene solutions are heated to
100°C the normal golden-yellow colour of cycloman-
ganated compounds is replaced abruptly by an intense
purple colour. This is reproducible on carefully purified
samples, and the colour change can be cycled through
several times by simply heating and cooling over the
range 90–100°C. No colour change is found in the solid
state, samples remaining yellow up to the decomposi-
tion temperature of about 140°C. This behaviour is
unprecendented in manganese chemistry. Ther-
mochroicity in other systems is often associated with
major changes in geometry but this does not seem likely
for this example as the crystal structures discussed
below show nothing unusual. Possibly there is a ther-
mally-accessible electronically excited state giving rise
to the colour change, but no confirmation of this could
be obtained.
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
The corresponding rhenium analogue 5b could be
made readily though higher temperatures were needed
for the cyclometallation reaction. This compound was
the expected pale-yellow and showed no signs of
thermochroism.
The infrared spectra of compounds 5 in the carbonyl
region gave the expected pattern for a cis-LL%M(CO)4
group. The positions of the peaks for the manganese
example 5a correspond most closely to the Se com-
pound in the series of orthomanganated Ph3PꢀX (XꢀO,
S, Se), rather than the XꢀO example which might have
been expected on electronegativity grounds [10]. The
Raman spectrum of 5a in the solid state gave doubled
peaks corresponding to those in the IR spectrum. The
explanation for this lies in the polymorphism of the
compound (see below), with the two different crystal
forms giving slightly shifted bands.
˚
11.1750(3), b=18.3067(4), c=11.7205(3) A, i=
90.737(1), V=2397.6(1) A , Dcalc=1.657 g cm−3, Z=
3
˚
4, F(000)=1192, v(Mo–Ka) 2.461 mm−1, Tmax 0.638,
Tmin 0.458, crystal size 0.42×0.40×0.32 mm3, T 203
K.
A total of 14266 reflections, 5509 unique (Rint 0.0181)
was collected 2°BqB28°. Final R1 0.0208 (4852 data
with I=2|(I)), 0.0243 (all data), wR2 0.0530, GoF
1.062, final De +0.32. Refined coordinates are in Table
4, and selected bond parameters are in the caption to
Fig. 3.
3. Results and discussion
3.1. Cyclomanganation of Ph3PꢀNPh
There is some inconsistency in the literature concern-
ing the PꢀN stretching frequency in Ph3PꢀNPh, having
been assigned to both the 1160–1180 and the 1325
Cyclometallation of Ph3PꢀNPh proceeded smoothly
in refluxing heptane, according to Eq. (1):

248
M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
1385 cm−1 regions [19]. Only IR spectra appear to have
been used previously. We find that in both the IR and
Raman spectra of Ph3PꢀNPh there is a strong peak at
1346 cm−1 and a weaker peak at 1171 cm−1. In the
orthomanganated complex the 1346 cm−1 peak has
disappeared, to be replaced by one at 1257 cm−1, so
these are assigned to the PꢀN stretches in the free and
complexed ligand respectively. The decrease of 89 cm−1
on coordination parallels the changes in the PꢀX fre-
quencies of Ph3PꢀX on cyclomanganation [10].
Table 5
Selected bond parameters for the three crystallographically indepen-
dent molecules of orthomanganated Ph3PꢀNPh, and for the free
ligand
Parameter
C2/c form C2/c form Cc form
Free ligand
[20]
(molecule 1) (molecule 2)
˚
Bond lengths (A)
Mn–N(1)
Mn–C(46)
PꢀN
2.110(3)
2.069(4)
1.603(3)
1.781(4)
1.438(5)
1.826(5)
1.834(5)
1.775(5)
1.852(5)
2.101(3)
2.080(5)
1.597(4)
1.784(4)
1.435(5)
1.860(5)
1.832(5)
1.794(5)
1.843(5)
2.105(4)
2.068(5)
1.594(4)
1.793(6)
1.426(6)
1.857(8)
1.825(7)
1.786(6)
1.849(7)
–
–
The 31P resonance of free Ph3PꢀNPh is at l 3.5, and
this moves to l 44.3 and 50.6 in the manganated and
rheniated derivatives respectively. Usually incorpora-
tion of phosphorus into a five-membered chelate ring
causes a shift in the 31P resonance of 21–33 ppm [20],
so the shifts observed here are unusually large and are
significantly more than the corresponding changes for
Ph3PꢀX (XꢀO, S. Se) [10].
X-ray crystallography was used to fully characterise
the new metallocyclic ring in 5a. Batches of crystals
from heptane consistently gave two types of crystals.
Both crystal structures were determined and were
shown to be polymorphs. The well-shaped paral-
lelepipeds were assigned to the space group Cc, while
the irregularly shaped ones were C2/c with two inde-
pendent molecules in the asymmetric unit. Therefore
the individual bond parameters were determined for
three independent molecules in all. However differences
between the molecules is confined to conformational
changes involving the free phenyl groups, so the follow-
ing discussion is based on average values.
1.602(3)
1.808(3)
1.330(5)
–
–
–
–
P–C(41)
N–C(11)
Mn–C(1)
Mn–C(2)
Mn–C(3)
Mn–C(4)
Bond angles (°)
Mn–N–P
N–P–C(41)
C(1)–Mn–C(4) 166.1(2)
N–Mn–C(46)
P–N–C(11)
117.2(2)
103.5(2)
118.5(2)
117.9(2)
103.5(2)
170.9(2)
83.2(2)
103.2(3)
171.6(3)
83.4(2)
115.3(2)
130.4(3)
84.0(2)
120.5(3)
121.1(2)
119.8(3)
molecules with the equivalent ones for the free ligand
[21]. The molecule consists of a Mn(CO)4 fragment
coordinated to the ligand via the expected Mn–N and
Mn–C bonds, with a bite angle at the Mn of 83.5°.
This generates a five-membered metallocycle containing
four different atom types, and incorporates a PꢀN
bond. The metallacyclic ring is essentially planar in all
A molecule of orthomanganated Ph3PꢀNPh is illus-
trated in Fig. 1, and Table 5 compares selected bond
parameters for the crystallographically independent
˚
three independent molecules to within 0.08 A. The
phenyl ring attached to the Mn is almost coplanar with
the metallocycle, with a maximum dihedral angle of
4.3° for one of the molecules in the C2/c form. The
N-phenyl ring is twisted away from coplanarity with
the metallocyclic ring by 89, 83 and 76° for the three
cases, in contrast to the free ligand where the corre-
sponding angle is 11°. This presumably arises from
steric interactions with the CO ligands on Mn, and
results in a lengthening of the N–Cphenyl distance from
˚
1.330(5) A in the parent [21] to an average value of
˚
1.433 A in the complexes as p-delocalisation with the
PꢀN group is prevented. At the same time the P–N–C
angle decreases from 130 to 120°. Surprisingly the PꢀN
bond length has not altered observably between the free
and complexed ligand, despite the drop in bond order
suggested by the change in the IR stretching frequency.
In the structures of orthomanganated Ph3PꢀX (XꢀS,
Se) there were significant changes [10]. In 5a the ex-
pected lengthening of the PꢀN bond on coordination is
presumably compensated for by the twisting of the
phenyl group out of plane; it is the N–C bond rather
than the PꢀN bond that changes.
Fig. 1. The structure of one of the independent molecules of or-
thomanganated Ph3PꢀNPh, 5a. The other molecules differ mainly in
the conformation of the free phenyl rings. The numbering scheme is
such that C(41), C(141), C(241), for example, refer to the same atom
in the Cc form, and molecules 1 and 2 of the C2/c form, respectively.

M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
249
˚
The Mn–N distance of 2.105 A is marginally longer
on coordination, while the Mn–O and Mn–Caryl bond
lengths are similar to those in other orthomanganated
O-donors. The only other parameter worth comment-
ing on is the As–O–Mn angle of 114.8°. In h1-R3AsꢀO
complexes the As–O–M angles average 135° [24], so
this presumably is the naturally preferred arrangement.
However formation of the metallocyclic ring of 6a
requires the more acute angle at the O atom and this
presumably introduces some strain. The parallel situa-
tion was discussed in more detail for the analogous
phosphorus compounds, where similar observations
hold [10].
˚
than in an orthomanganated organic imine (2.070 A)
[22] or arylhydrazone (2.053 A) [23]. The Mn–CO bond
trans to the N atom is significantly shorter than that
trans to the metallated C atom, which in turn is shorter
than the two Mn–CO bonds trans to each other,
following the established pattern [1].
˚
3.2. Cyclomanganation of Ph3AsꢀO and Ph3AsꢀS
Reaction of Ph3AsꢀX with PhCH2Mn(CO)5 in reflux-
ing heptane (the usual conditions for cyclomangana-
tion) gave extensive decomposition and formed only
low yields of the expected products. However, under
milder conditions (refluxing hexane) the orthoman-
ganated species 6 were formed in moderate yields Eq. 2.
3.3. Attempted cyclometallation of Ph3As
As mentioned in the introduction Kaesz%s group suc-
cessfully characterised orthomanganated PPh3, com-
pound 2, with a four-membered ring [7]. We attempted
the parallel reaction of PhCH2Mn(CO)5 with AsPh3.
This proved to be a complicated system, giving rise to
many products in low yields, none of which appeared
to correspond to the arsenic analogue of 2. Presumably
the larger size of As compared to P discourages the
formation of a small ring. The only species identified
were PhCH2Mn(CO)4(AsPh3) (the expected first-formed
compound), cyclomanganated Ph3AsꢀO (arising from
in situ oxidation of Ph3As) and a red complex which
was shown by an X-ray structure determination to be a
dimanganese complex 7 with a bridging AsPh2 ligand
and a bridging, h1, h6-benzyl group. The structure is
shown in Fig. 3.
(2)
The new complexes were identified readily by IR, NMR
and ESMS spectra, which matched those of the corre-
sponding phosphorus analogues [10].
The low yield of the oxide derivative was similar to
that for the equivalent Ph3PꢀO system, and can be
attributed to combining the hard O-donor with the soft
acceptor Mn(I), and possibly to the need for an acute
angle at O when the metallocyclic ring is formed (see
below).
The coordination around Mn(1) is equivalent to that
in a molecule such as cis-PhCH2Mn(CO)4(AsPh3),
while that around Mn(2) is related to (h6-
For the sulfide the low yield can be attributed to
decomposition of the arsenic sulfide, since appreciable
quantities of cis-PhCH2Mn(CO)4(AsPPh3) were also
formed. Ph3AsꢀS is known to be relatively unstable (the
corresponding selenide cannot be isolated) and in situ
formation of Ph3As provides an alternative ligand for
attack at the manganese atom. In this respect the
reaction is similar to that of Ph3PꢀSe, where by-prod-
ucts incorporating Ph3P and Se separately were found
[10].
These are the first examples of cyclometallation reac-
tions involving arsenic chalcogenides so a structure
determination of the oxide was carried out. The
Fig. 2. The structure of orthomanganated Ph3AsꢀO, 6a. Selected
bond lengths (A): As(1)–O(11) 1.684(2), Mn(1)–O(11) 2.084(2),
Mn(1)–C(12) 2.080(3), As(1)–C(11) 1.884(3), Mn(1)–C(1) 1.842(3),
Mn(1)–C(2) 1.839(3), Mn(1)–C(3) 1.774(3), Mn(1)–C(4) 1.851(3);
bond angles: O(11)–Mn(1)–C(12) 87.34(9)°, As(1)–O(11)–Mn(1)
114.8(1)°, C(11)–As(1)–O(11) 104.3(1)°.
˚
molecule is illustrated in Fig. 2, and shows the expected
¸¹¹¹º
planar MnOAsC2 metallocyclic ring, with a C–Mn–O
chelating angle of 87°, close to the ideal for octahedral
˚
manganese. The AsꢀO distance has increased by 0.04 A

250
M.A. Leeson et al. / Journal of Organometallic Chemistry 579 (1999) 243–251
cyclomanganation reactions and presumably will form
corresponding species with other metallating agents,
such as Pd(II). The product 5 is stable showing that the
PꢀN bond can be accommodated readily in a metallo-
cyclic ring.
The triphenylarsine oxide and sulfide do form cyclo-
manganated complexes analogous to those of triphenyl
phosphine, but the yields are rather low. However once
formed they show appreciable stability.
Cyclometallation of Ph3As with manganese is less
favourable than for Ph3P, presumably because of the
larger size of As and because the weaker As–C bond
allows alternative reaction paths.
5. Supplementary material
Fig. 3. The molecular structure of (m–h1,h6-C6H5CH2)(m-
˚
Crystallographic data for structural analysis has been
deposited with the Cambridge Crystallographic Data
Centre, for compounds 5a, 6a and 7. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (Fax: +44-1223-336-033; e-mail: de-
posit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.
ac.uk.
AsPh2)Mn2(CO)6, 7. Selected bond lengths (A): Mn(1)–As(1)
2.465(1), Mn(2)–As(1) 2.400(1), Mn(1)–C(1) 2.189(2), As(1)–C(31)
1.970(2), As(1)–C(41) 1.964(2), Mn(1)–CO(av.) 1.826(2), Mn(2)–
CO(av.) 1.790(2); bond angles: Mn(1)–As(1)–Mn(2) 112.00(1)°,
C(31)–As(1)–C(41) 97.27(7)°, Mn(1)–C(1)–C(2) 117.4(1)°.
C6H6)Mn(CO)2(SPh), for example [25]. Electron count-
ing suggests that the bridging AsPh2 ligand is acting as
a two-electron donor to Mn(1) and a one-electron
donor to Mn(2); this is not obvious from the As–Mn
˚
bond lengths (As(1)–Mn(1) 2.465 A, As(1)–Mn(2)
˚
2.400 A) but any effects will be masked by the elec-
Acknowledgements
tronic differences at the two Mn centres. This is indi-
cated by the average Mn–CO distances of 1.826 and
We thank Associate Professor Cliff Rickard and
Allen Oliver, University of Auckland and Professor
Ward T. Robinson, University of Canterbury, for X-
ray data sets.
˚
1.790 A for Mn(1) and Mn(2), respectively. The Mn–
C(1)–C(2) angle of 117° and the Mn(1)–As(1)–Mn(2)
angle of 112° shows the molecule fits together with little
strain, though the C–As–C angle of 97.27° is notice-
ably acute. Although this doubly bridged arrangement
appears to be unique the individual parts have parallels
in the literature. Ph2P is a common bridging ligand in
manganese chemistry so Ph2As is acting in the same
way, and there are examples of benzyl acting as an
h6-ligand to Cr(CO)3, and binding h1 to another metal
[26]. A more complicated example of a h1,h6-benzyl
ligand on a Ru8 cluster is also established [27].
How compound 7 forms in the reaction mixture is
obscure, though clearly As–C bond cleavage is in-
volved and presumably takes place more readily than
corresponding cleavage of P–C bonds.
Pyrolysis of pre-formed cis-PhCH2Mn(CO)4(AsPh3)
was attempted in the hope of a more specific reaction,
but again many compounds formed in small yields so
the system was not further investigated.
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3

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