Bis[hydrazido(2-)] and related complexes of molybdenum(VI): Towards alkene-metathesis catalysts based on hydrazido(2-) ligation

Article abstract of DOI:10.1039/a606575i

The complex [Mo(NBu^t)₂Cl₂(dme)](dme = 1,2-dimethoxyethane) underwent an imide-ligand exchange reaction with an excess of 1,1-diphenylhydrazine hydrochloride in refluxing dme to give the bis[hydrazido(2-)] complex [MoCl₂(NNPh₂)₂(dme)] 1. Reaction of 1 with an excess of PMe₃ in CH₂Cl₂ gave [MoCl₂(NNPh₂)₂(PMe₃)₂] 2. Treatment of Na₂[MoO₄] with 2 molar equivalents of Ph₂NNH₂·HCl in the presence of NEt₃ and SiMe₃Cl in refluxing dme afforded the salt [NHEt₃][MoCl₄(NNPh₂)(NHNPh₂)] 3. The crystal structures of 1-3 have been determined; all possess octahedral geometries with unidentate hydrazido groups. The hydrazido(2-) Mo-N bond distances vary from 1.749(2) and 1.771(2) A in 1, to 1.793(3) in 2 and 1.748(2) A in 3, with no simple correlation with the Mo-Nα-Nβ angle. The anionic component of 3 contains a bent hydrazide(1-) ligand (Mo-N-N 136.0°) and a linear hydrazido(2-) group (Mo-N-N 174.4°).

Full text of DOI:10.1039/a606575i

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Bis[hydrazido(2Ϫ)] and related complexes of molybdenum(VI): towards
alkene-metathesis catalysts based on hydrazido(2Ϫ) ligation
Jonathan R. Dilworth,*,a Vernon C. Gibson,*,b Canzhong Lu,a John R. Miller,a Carl Redshawb and
Yifan Zhenga
a
Department of Biological and Chemical Sciences, University of Essex, Wivenhoe Park,
Colchester CO4 3SQ, UK
b Department of Chemistry, Imperial College, London SW7 2AY, UK
The complex [Mo(NBut)2Cl2(dme)] (dme = 1,2-dimethoxyethane) underwent an imide-ligand exchange reaction
with an excess of 1,1-diphenylhydrazine hydrochloride in refluxing dme to give the bis[hydrazido(2Ϫ)] complex
[MoCl2(NNPh2)2(dme)] 1. Reaction of 1 with an excess of PMe3 in CH2Cl2 gave [MoCl2(NNPh2)2(PMe3)2] 2.
Treatment of Na2[MoO4] with 2 molar equivalents of Ph2NNH2ؒHCl in the presence of NEt3 and SiMe3Cl in
refluxing dme afforded the salt [NHEt3][MoCl4(NNPh2)(NHNPh2)] 3. The crystal structures of 1–3 have been
determined; all possess octahedral geometries with unidentate hydrazido groups. The hydrazido(2Ϫ) Mo᎐N bond
distances vary from 1.749(2) and 1.771(2) Å in 1, to 1.793(3) in 2 and 1.748(2) Å in 3, with no simple correlation
with the Mo᎐Nα᎐Nβ angle. The anionic component of 3 contains a bent hydrazide(1Ϫ) ligand (Mo᎐N᎐N 136.0Њ)
and a linear hydrazido(2Ϫ) group (Mo᎐N᎐N 174.4Њ).
Imide ligands play a central role in the stabilization of well-
defined metathesis catalysts of molybdenum,1 tungsten 2 and
rhenium.3 The four-co-ordinate molybdenum complexes
[Mo(NC6H3Pri2-2,6)(CHCMe2Ph)(OR)2] [R = CMe3, CMe2-
(CF3) or CMe(CF3)2] in particular have found widespread
application in the controlled synthesis of polymers via ring-
opening metathesis polymerization.4 In view of the close iso-
electronic relationship between the hydrazide(2Ϫ) ligand and
the imido (NR) group, we have embarked upon a programme
of study aimed at exploring the potential of hydrazide ligands
for stabilizing a new family of well defined metathesis catalysts.
Here, we report the synthesis, characterization and crystal
structures of several important precursors.
Results and Discussion
We have recently shown that the complex [MoCl2(NBut)2(dme)]
(dme = 1,2-dimethoxyethane) undergoes imide ligand exchange
upon treatment with anilines in dme at 70 ЊC.5 This synthetic
Fig. 1 Molecular structure of complex 1, without H atoms and with
procedure is quite general and we show here that it can be
extended to the synthesis of hydrazido(2Ϫ) complexes by
treatment of bis(imido)molybdenum precursors with the
hydrochloride salt of diphenylhydrazine.
key atoms labelled
thf in the presence of an excess of trimethylphosphine afforded
orange crystalline [MoCl2(NNPh2)2(PMe3)2] 2. Room-
temperature NMR data reveal a virtually coupled triplet
The reaction of [MoCl2(NBut)2(dme)] with Ph2NNH2ؒHCl (2
equivalents) in refluxing dme (ca. 2 h) readily gives multigram
quantities of [MoCl2(NNPh2)2(dme)] 1 as an orange solid.
Complex 1 shows a single νN N stretch at 1586 cmϪ1. Crystals
suitable for an X-ray analysis were grown from dme at Ϫ20 ЊC;
the molecular structure is shown in Fig. 1. Bond lengths and
angles are collected in Table 1 and crystal data are given in
Table 4. The molecular geometry is distorted octahedral with
trans chloride and cis hydrazido(2Ϫ) groups. The
N(1)᎐Mo᎐N(3) angle is 105.56(10)Њ, the cis O(1)᎐Mo᎐Cl(2) and
trans Cl(2)᎐Mo᎐Cl(1) angles are 85.99(5)Њ and 162.14(3)Њ
respectively. The two hydrazide(2Ϫ) ligands are somewhat
different: the Mo᎐N distances are short [Mo᎐N(1) 1.749(2),
Mo᎐N(3) 1.771(2) Å], the former is the shortest reported to
date for the cis-{M(NNR2)2} core.6 The corresponding
Mo᎐N᎐N angles are 173.4(2) and 154.6(2)Њ. By comparison
with analogous bis(imido)molybdenum complexes, the latter is
likely to be at the lower limit for a linear hydrazido(2Ϫ) group.
Treatment of complex 1 with 1 equivalent of magnesium in
centred at δ 1.55 in the 1H NMR spectrum and a singlet in the 31
P
NMR spectrum (δ 5.92) consistent with a structure in which the
two phosphines are equivalent. Crystals of 2 suitable for a
structure determination were grown by diffusion of heptane
into a saturated CH2Cl2 solution. Fig. 2 shows the cis chloride,
trans phosphine pseudo-octahedral geometry of 2. The crystal
data are given in Table 4 and selected bond lengths and angles
are in Table 2. The molecules lie on crystallographic two-fold
axes. The Mo᎐N separation of 1.793(3) Å and the associated
Mo᎐N(1)᎐N(2) angle of 175.2(2)Њ are consistent with linear
hydrazido(2Ϫ) units.
Attempts to isolate complex 1 by interaction of Na2[MoO4]
with Ph2NNH2ؒHCl in the presence of NEt3 and SiMe3Cl in
refluxing dme led, after work-up, to a diamagnetic purple crys-
talline solid. Infrared data showed a N᎐H stretch at 3208 cmϪ1
and a strong νN N stretch at 1585 cmϪ1, while the 1H NMR spec-
trum contained resonances at δ ca. 8.2 (br) and ca. 12.9 (sharp)
due to two different nitrogen-bound hydrogens. Analytical data
J. Chem. Soc., Dalton Trans., 1997, Pages 269–272
269

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Table 1 Selected bond lengths (Å) and angles (Њ) for complex 1
Table 3 Selected bond lengths (Å) and angles (Њ) for complex 3
Mo᎐N(1)
Mo᎐O(1)
Mo᎐Cl(2)
N(1)᎐N(2)
N(2)᎐C(21)
N(4)᎐C(31)
1.749(2)
2.322(2)
2.4380(9)
1.324(3)
1.435(3)
1.421(3)
Mo᎐N(3)
Mo᎐O(2)
Mo᎐Cl(1)
N(2)᎐C(11)
N(3)᎐N(4)
N(4)᎐C(41)
1.771(2)
2.331(2)
2.4451(9)
1.430(3)
1.326(3)
1.440(3)
Mo᎐Cl(1)
Mo᎐Cl(3)
Mo᎐N(1)
N(1)᎐N(2)
H᎐Cl(3)
2.4448(7)
2.4213(7)
1.748(2)
1.304(3)
2.579(1)
Mo᎐Cl(2)
Mo᎐Cl(4)
Mo᎐N(3)
N(3)᎐N(4)
H(1)᎐Cl(2)
2.4788(7)
2.4641(7)
1.958(2)
1.358(3)
2.573(1)
Cl(1)᎐Mo᎐Cl(2)
Cl(1)᎐Mo᎐Cl(4)
Cl(1)᎐Mo᎐N(3)
Cl(2)᎐Mo᎐Cl(4)
Cl(2)᎐Mo᎐N(3)
Cl(3)᎐Mo᎐N(1)
Cl(4)᎐Mo᎐N(1)
N(1)᎐Mo᎐N(3)
N(1)᎐N(2)᎐C(11)
C(11)᎐N(2)᎐C(21)
N(3)᎐N(4)᎐C(31)
C(31)᎐N(4)᎐C(41)
84.51(3)
85.73(3)
86.43(7)
87.70(3)
82.97(6)
94.58(7)
92.10(7)
97.15(9)
119.8(2)
121.3(2)
118.5(2)
120.7(2)
C(1)᎐Mo᎐Cl(3)
Cl(1)᎐Mo᎐N(1)
Cl(2)᎐Mo᎐Cl(3)
Cl(2)᎐Mo᎐N(1)
Cl(3)᎐Mo᎐Cl(4)
Cl(3)᎐Mo᎐N(3)
Cl(4)᎐Mo᎐N(3)
Mo᎐N(1)᎐N(2)
N(1)᎐N(2)᎐C(21)
Mo᎐N(3)᎐N(4)
N(3)᎐N(4)᎐C(41)
169.31(3)
94.82(7)
86.07(3)
179.32(7)
88.85(3)
97.43(7)
168.34(7)
174.4(2)
118.8(2)
136.0(2)
119.0(2)
N(1)᎐Mo᎐N(3)
N(3)᎐Mo᎐O(1)
N(3)᎐Mo᎐O(2)
N(1)᎐Mo᎐Cl(2)
O(1)᎐Mo᎐Cl(2)
N(1)᎐Mo᎐Cl(1)
O(1)᎐Mo᎐Cl(1)
Cl(2)᎐Mo᎐Cl(1)
N(1)᎐N(2)᎐C(11)
105.56(10)
89.75(9)
159.68(9)
97.19(7)
85.99(5)
94.23(7)
79.40(5)
162.14(3)
120.0(2)
N(1)᎐Mo᎐O(1)
N(1)᎐Mo᎐O(2)
O(1)᎐Mo᎐O(2)
N(3)᎐Mo᎐Cl(2)
O(2)᎐Mo᎐Cl(2)
N(3)᎐Mo᎐Cl(1)
O(2)᎐Mo᎐Cl(1)
N(2)᎐N(1)᎐Mo
N(1)᎐N(2)᎐C(21)
N(4)᎐N(3)᎐Mo
N(3)᎐N(4)᎐C(41)
164.13(8)
94.46(9)
70.60(7)
92.88(8)
80.98(6)
97.23(8)
84.49(5)
173.4(2)
116.3(2)
154.6(2)
118.6(2)
C(11)᎐N(2)᎐C(21) 122.2(2)
N(3)᎐N(4)᎐C(31) 118.3(2)
C(31)᎐N(4)᎐C(41) 122.6(2)
Table 2 Selected bond lengths (Å) and angles (Њ) for complex 2
Mo᎐N(1)
Mo᎐P
Mo᎐Cl
P᎐C(2)
P᎐C(1)
1.793(3)
P᎐C(3)
1.811(4)
1.306(4)
1.432(4)
1.450(4)
2.5141(12)
2.5625(11)
1.805(5)
N(1)᎐N(2)
N(2)᎐C(11)
N(2)᎐C(21)
1.810(4)
N(1)᎐Mo᎐N(1I)
N(1)᎐Mo᎐P
N(1)᎐Mo᎐PI
P᎐Mo᎐PI
103.6(2)
92.59(9)
93.02(9)
170.92(5)
165.80(9)
82.45(4)
90.03(9)
P᎐Mo᎐Cl
90.42(4)
76.76(5)
175.2(2)
121.4(3)
119.7(3)
118.8(3)
ClI᎐Mo᎐Cl
N(2)᎐N(1)᎐Mo
N(1)᎐N(2)᎐C(11)
N(1)᎐N(2)᎐C(21)
C(11)᎐N(2)᎐C(21)
N(1)᎐Mo᎐ClI
P᎐Mo᎐ClI
N(1)᎐Mo᎐Cl
Symmetry relation: I Ϫx, y, Ϫz + ¹.
¯
²
Fig. 3 Molecular structure of complex 3, without H atoms and with
key atoms labelled
planar environment. The atoms Mo, Cl(2), N(1), N(2), N(3)
and N(4) are virtually coplanar [maximum deviation through
the best plane 0.026 Å for N(3)], and the Mo᎐N(3)᎐N(4) unit
bends towards the Mo᎐N(1)᎐N(2) fragment most likely in order
to accommodate a bond to a hydrogen atom (see below).
In order to account for the diamagnetism of the compound
and the presence of N᎐H stretching frequencies in the infrared
spectrum, the anion has to contain a hydrogen atom not
detected by the X-rays but attached to a nitrogen atom; we have
placed this hydrogen atom on the first N atom, N(3), of the bent
NNPh2 ligand, which would normally imply its description as a
‘N,N-diphenylhydrazido(1Ϫ)’ group; the internal geometry,
particularly the coplanarity of N(4) with N(3), C(31) and
C(41), suggests however that it could also be described as a
protonated diphenylisodiazene. The calculated position of H(1)
places it 2.57 Å from Cl(2), consistent with an internal hydro-
gen bond. The C and N atoms of the triethylammonium cation
are very well defined in the structure determination and the N-
bound hydrogen atom was placed in a calculated position
0.9 Å from the N atom. This position indicates that it is hydro-
gen bonded to Cl(3) and Cl(4), with H ؒ ؒ ؒ Cl distances of 2.58
and 2.72 Å respectively; thus in the solid state 3 is an ion pair.
The internal geometry of the NαNβPh2 units in complexes 1–
3 and in many other complexes of this type, supports the sug-
gestion 7 that these ligands are described more accurately as
‘isodiazene’ than as ‘hydrazido(2Ϫ)’. The coplanarity of the
three bonds to Nβ is a constant theme, pointing to Nβ being
conjugated. The Nα᎐Nβ bond distances are intermediate
between those for single and double bonds8 (single bond, 1.40–
1.46; double bond, 1.22–1.26 Å). Even in the protonated ligand
of 3, Nβ is trigonal planar and the N᎐N distance is only
1.358(3) Å . Isoelectronic with ketones, isodiazenes would be
Fig. 2 Molecular structure of complex 2, without H atoms and with
key atoms labelled
were consistent with the stoichiometry [NHEt3][MoCl4-
(NNPh2)(NHNPh2)] 3. The structure was determined by X-ray
diffraction and a view of the ion pair is shown in Fig. 3.
Selected bond lengths and angles and crystal data are given in
Tables 3 and 4 respectively. The structure contains a pseudo-
octahedral anionic molybdenum fragment with cis NNPh2
units bound in two different ways. One has the linear Mo᎐N᎐N
arrangement, with short M᎐N and N᎐N bonds and a trigonal-
planar arrangement of the N(2) atom, and may be described as
a ‘hydrazide(2Ϫ)’ ligand, or better related to its geometry, as an
‘isodiazene’.7 The other ligand is notably different, with a
Mo᎐N᎐N angle of 136.0(2)Њ, a Mo᎐N distance of 1.958(2) Å
and a N᎐N distance of 1.358(3) Å. Atom N(4) has a trigonal-
270
J. Chem. Soc., Dalton Trans., 1997, Pages 269–272

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Table 4 Crystal structure determinations for complexes 1–3
1
2
3
Empirical formula
M
C28H30Cl2MoN4O2
621.40
C15H19ClMo0.5N2P
341.71
C30H37Cl4MoN5
705.4
Crystal size/mm
Crystal system
Space group
0.25 × 0.5 × 0.56
Monoclinic
P21/n
0.39 × 0.72 × 0.83
Orthorhombic
Pbcn
0.2 × 0.3 × 0.7
Monoclinic
P21/n
a/Å
b/Å
c/Å
15.981(5)
9.984(2)
17.688(5)
97.78(2)
2796.1(13)
4
1.476
0.692
1272
9.278(3)
21.692(7)
16.097(9)
12.1775(36)
10.6011(9)
26.4756(97)
99.44(2)
3371.5(1.6)
4
1.390
0.725
1448
β/Њ
U/Å3
3240(2)
8
1.401
0.694
Z
Dc/g cmϪ3
µ(Mo-Kα)/mmϪ1
F(000)
1408
T/K
291
291
291
2θ Range/Њ
hkl Range
1.61–25.02
0–18, 0–11, Ϫ21 to 20
5096
1.88–24.98
0–11, Ϫ25 to 19, 0–19
5419
1.5–25.0
0–14, Ϫ12–0, Ϫ31 to 31
6620
Reflections collected
Independent reflections (Rint
Reflections observed
Absorption correction Tmax, Tmin
Weighting scheme, w
)
4910 (0.0121)
4004 [I > 2 σ (I)]
1.00, 0.92
1/[σ2(Fo2) + (0.0299P)2 +
2827 (0.0414)
2240 [I > 2 σ (I)]
1.00, 0.857
1/[σ2(Fo2) + (0.0475P)2 +
6305 (0.013)
5016 [I > 1.5 σ (I)]
1.00, 0.93
1/[σ2(Fo) + (0.02Fo)2]
1.4945P], P = (Fo2 + 2Fc )/3
0.9756P], P = (Fo2 + 2Fc )/3
2
2
Data, restraints, parameters
4910, 0, 454
0.0267, 0.0678
1.193
2827, 0, 177
0.0475, 0.1033
1.251
5016, 0, 361
0.034, 0.046b
1.80d
R1, wR2a
S c
a
2
2
2
2
2
c
2
2 2
R1 = Σ |F ϪF |/Σ|F |, wR2 = {[Σw(F ) Ϫ (F ) ] /Σw(F ) } . b wR = [Σw(Fo ϪFc)2/ΣwFo ] . [Σw(F ) Ϫ (F ) ] /(n Ϫ p)] where n = number of reflections
¹
¹
¹
¯
¯
¯
²
²
²
o
c
o
o
c
o
o
c
¹
and p = total number of parameters. d [Σw(Fo Ϫ Fc) /(nϪp)]².
2

expected to have two Nα lone pairs in the NαNβC2 plane (alter-
natively regarded as a combination of a σ lone pair on the NN
vector and a π pair in the NNC2 plane); Nα would be expected
to be more basic, and therefore a better donor, than the O atom
of a ketone as it carries an effective negative charge. We suggest
that the difference between the isodiazene and hydrazido(2Ϫ)
descriptions is real because hydrazido(2Ϫ) complexes should
have pyramidally bound Nβ atoms and distinctly longer N᎐N
distances. Assignment of the ligands as electronically neutral
isodiazenes implies that they are derived from hydrazines by
oxidation rather than via reductive deprotonation.
The Mo᎐N distances in all the complexes suggest multiple-
bond character except for the protonated ligand of 3, where the
distance of 1.958(2) Å is readily assigned to a single bond; this
is also consistent with the Mo᎐Nα᎐Nβ angle of 136.0(2)Њ, i.e.
one of the Nα lone pairs co-ordinates to Mo, the other to H+.
Among the unprotonated ligands there is no correlation
between bond distances and the Mo᎐Nα᎐Nβ angle.
Syntheses
[MoCl2(NNPh2)2(dme)] 1. The complex [MoCl2(NBut)2(dme)]
(1.0 g, 2.5 mmol) and Ph2NNH2ؒHCl (1.1 g, 5.0 mmol) in dme
(30 cm3) were refluxed for 12 h. After filtration and concentra-
tion (to ca. 20 cm3) deep orange prisms of the product were
deposited on standing at room temperature. Yield 0.48 g, 31%.
Further crops can be obtained from the mother-liquor; overall
yield 70% (Found: C, 54.1; H, 4.9; N, 9.1. C28H30Cl2MoN4O2
requires C, 54.1; H, 4.9; N, 9.0%). IR: 2711w, 2600w, 2500w,
2078w, 1586s, 1511w, 1328w, 1298m, 1262s, 1158s, 1087 (br) bs,
1043s, 922w, 862s, 848m, 801s, 760s, 692s, 654w, 634m, 530w
and 494m cmϪ1. NMR (CDCl3): H (400 MHz), δ 7.31 (m,
1
8 H, o-H), 7.13 (m, 8 H, m-H), 6.94 (m, 4 H, p-H), 3.96 (s, 4 H,
CH2) and 3.52 (s, 6 H, CH3); 13C-{1H} (75 MHz), δ 142.77,
128.39, 125.58, 120.87, 71.01 (s, CH2 of dme) and 63.86 (s, CH3
of dme).
[MoCl2(NNPh2)2(PMe3)2] 2. Trimethylphosphine (0.21 cm3,
2.0 mmol) was added to [MoCl2(NNPh2)2(dme)] (0.5 g, 0.8
mmol) and Mg (0.02 g, 0.83 mmol) in thf (30 cm3). After stir-
ring for 12 h, the volatiles were removed under reduced pressure
and the residue was taken up in CH2Cl2 (20 cm3). Diffusion of
heptane into CH2Cl2 gave orange prisms. Yield 0.4 g, 82%
(Found: C, 52.5; H, 5.7; N, 8.0. C30H38MoN4P2ؒCH2Cl2
requires C, 53.3; H, 5.8; N, 8.0%). IR: 1587w, 1338w, 1294m,
1250w, 1163w, 948m, 755w, 692w, 497w, 476w, 358w 330w,
314w, 294m and 251vs cmϪ1. NMR (CDCl3): 1H (400 MHz), δ
7.19 (m, 16 H, o,m-H), 7.06 (tt, 4 H, J = 6.8, JЈ = 1.6, p-H) and
1.55 (t, 18 H, J = 4.0 Hz, PMe3); 13C-{1H} (75 MHz), δ 146.39,
131.64, 128.66, 124.29, 17.72 (t, J = 13.0 Hz, PMe3); 31P (162
MHz), δ 5.92 (s).
The derivative chemistry of these hydrazido(2Ϫ) complexes
is under development and will be reported at a future date.
Experimental
General
All manipulations were carried out under an atmosphere of
nitrogen using standard Schlenk and cannula techniques or in a
conventional nitrogen-filled glove-box. Solvents were refluxed
over an appropriate drying agent, and distilled and degassed
prior to use. Elemental analyses were performed by the micro-
analytical services of the Department of Chemistry at Durham
and Medac Ltd. The NMR spectra were recorded on a Varian
VXR 400 S spectrometer at 400.0 (1H) and 162.0 MHz (31P,
referenced to dilute aqueous H3PO4, δ 0) and a Bruker DRX
300 machine at 75.0 MHz (13C); chemical shifts are referenced to
the residual protio impurity of the deuteriated solvent. The IR
spectra (Nujol mulls, CsI or KBr windows) were recorded on
Perkin-Elmer 577 and 457 grating spectrophotometers. The
complex [Mo(NBut)2Cl2]ؒdme9 was prepared by the literature
method. All other chemicals were obtained commercially and
used as received unless stated otherwise.
[NHEt3][MoCl4(NNPh2)(NHNPh2)] 3. Triethylamine (13.6
cm3, 97.6 mmol) and SiMe3Cl (24.5 cm3, 193.0 mmol) were
added to Na2[MoO4] (5.0 g, 24.3 mmol) and Ph2NNH2ؒHCl
(10.72 g, 48.5 mmol) in dme (ca. 20 cm3). After refluxing for 12 h
the suspension was filtered whilst hot. Purple lustrous crystals
of complex 3 were deposited on standing at room temperature
(2.81 g, 16.4% isolated yield) (Found: C, 51.2; H, 5.3; N, 9.8.
J. Chem. Soc., Dalton Trans., 1997, Pages 269–272
271

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C30H37Cl4MoN5 requires C, 51.0; H, 5.3; N, 9.9%). IR: 3208w,
1585m, 1460s, 1377s, 1261s, 1154m, 806m, 758s, 734m, 693s,
hole: 0.710 and Ϫ0.229 e ÅϪ3. The maximum shift/e.s.d. was
< 0.01.
Atomic coordinates, thermal parameters, and bond lengths
1
654s, 610m, 522w and 496m cmϪ1. NMR (CDCl3): H (400
MHz), δ 12.94 (s, 1 H, NHNPh2), 8.29 (br s, 1 H, Et3NH), 7.17–
7.05 (m, 18 H, o,m-H), 6.89 (t, 2 H, J = 7.4, p-H), 3.21 (m, 6 H,
CH2CH3) and 1.31 (t, 9 H, J = 7.2 Hz, CH2CH3); 13C-{1H} (75
MHz), δ 144.48, 137.98, 129.49, 128.96, 127.89, 127.36, 124.02,
122.57, 47.12 and 9.13.
and angles have been deposited at the Cambridge Crystallo-
graphic Data Centre (CCDC). See Instructions for Authors,
J. Chem. Soc., Dalton Trans., 1977, Issue 1. Any request to the
CCDC for this material should quote the full literature citation
and the reference number 186/293.
X-Ray crystallography
Acknowledgements
Numerical data are summarised in Table 4.
The EPSRC is gratefully acknowledged for a grant to J. R. D.
and V. C. G.
Data collection. Intensity data were collected on an Enraf-
Nonius diffractometer with monochromated Mo-Kα radi-
ation (λ = 0.710 73 Å). Cell constants were obtained from
least-squares refinement of the setting angles of 25 centred
reflections in the range 20 < θ < 25Њ for complex 1, 20 < θ < 22Њ
for 2 and 22 < θ < 25Њ for 3. The data were collected in the ω–2θ
scan mode and three standard reflections were measured every
3 h of exposure; 4.5 (for 1), 0 (2) and 6.0% (3) loss of intensity
was observed which was linearly corrected during processing.
Three standard reflections were measured every 200 to check
the crystal orientation. The data were corrected for Lorentz-
polarization factors and an absorption correction was applied
using ψ scans of nine reflections.
References
1 R. R. Schrock, J. S. Murdzek, C. G. Bazan, J. Robbins, M. DiMare
and M. O’Regan, J. Am. Chem. Soc., 1990, 112, 3875; H. H. Fox,
K. B. Yap, J. Robbins, S. Cai and R. R. Schrock, Inorg Chem., 1992,
31, 2287; H. H. Fox, J.-K. Lee, L. Y. Park and R. R. Schrock,
Organometallics, 1993, 12, 759.
2 R. R. Schrock, R. T. Depue, J. Feldman, K. B. Yap, D. C. Yang,
W. M. Davies, L. Y. Park, M. DiMare, M. Schofield, J. Anhaus,
E. Walborsky, E. Evitt, C. Kruger and P. Betz, Organometallics,
1990, 9, 2262; R. R. Schrock, R. T. Depue, J. Feldman, C. J. Schave-
rian, J. C. Dewan and A. H. Liu, J. Am. Chem. Soc., 1988, 110, 1423.
3 R. Toreki and R. R. Schrock, J. Am. Chem. Soc., 1990, 112, 2448;
R. Toreki, R. R. Schrock and W. M. Davies, J. Am. Chem. Soc.,
1992, 114, 3367.
4 See V. C. Gibson, Adv. Mater., 1994, 6, 37 and refs. therein.
5 A. Bell, W. Clegg, P. W. Dyer, M. R. J. Elsegood, V. C. Gibson and
E. L. Marshall, J. Chem. Soc., Chem. Commun., 1994, 2547.
6 P. B. Kettler, Y. D. Chang and J. Zubieta, Inorg Chem., 1994, 33,
5870.
7 A. A. Danopoulos, G. Wilkinson and D. J. Williams, J. Chem. Soc.,
Dalton Trans., 1994, 907.
8 F. H. Allen, O. Kennard, D. G. Watson, L. Brammer and A. G.
Orpen, J. Chem. Soc., Perkin Trans. 2, 1987, S1.
Structure analysis and refinement. Structures 1 and 2 were
2
solved via direct methods (core atoms)10 and refined on Fo by
full-matrix least squares.11 All non-hydrogen atoms were aniso-
tropic. The hydrogen atoms were revealed by Fourier-difference
synthesis and isotropically refined. The weighting scheme gave
satisfactory agreement. Final R indices [I > 2σ (I)]: for 1, R1 (on
F) 0.0267, wR2 (on F2) 0.0678; for 2, 0.0475, 0.1033. Largest
difference peak and hole: for 1, 0.0245 and Ϫ0.447; for 2, 0.679
and Ϫ0.429 e ÅϪ3. Maximum shift/e.s.d. was Ϫ0.212 (for 1)
and Ϫ0.001 (for 2). Sources of scattering factors were as in
ref. 11.
9 P. W. Dyer, V. C. Gibson, J. A. K. Howard, B. Whittle and
C. Wilson, Polyhedron, 1995, 14, 103.
10 G. M. Sheldrick, SHELXS 86, University of Göttingen, 1986
11 G. M. Sheldrick, SHELXL 93, Program for Crystal Structure
Refinement, University of Göttingen, 1993.
Structure 3 was solved by the Patterson heavy-atom method
and refined on Fo by full-matrix least squares.12 All non-
hydrogen atoms were anisotropic. The hydrogen atoms were
included in calculated positions. Final R indices [Fo > 3 σ (Fo)]:
R1 (on F) 0.034, RЈ (on F) 0.046. Largest difference peak and
12 MOLEN, An Interactive Structure Solution Procedure, Enraf-
Nonius, Delft, 1990.
Received 24th September 1996; Paper 6/06575I
272
J. Chem. Soc., Dalton Trans., 1997, Pages 269–272