Synthesis and characterisation of molybdenum complexes bearing highly functionalised imido substituents

Article abstract of DOI:10.1039/a701502j

The monofunctionalised anilines 2-(H₂N)C₆H₄X (where X = CO₂H, SO₃H, or CN) reacted with sodium molybdate in the presence of NEt₃ and SiMe₃Cl in refluxing dme (1,2-dimethoxyethane) to give [NEt₃H][MoCl₃-{2-(HN)C₆H₄CO ₂} {2-Me₃SiO₂CC₆H₄N}] 1, [NEt₃H]₂[MoCl₃{2-NC₆H ₄SO₃} {2-(HN)C₆H₄SO₃}] 2 and [MoCl₂-(2-NCC₆H₄N)₂(dme)] 3. Treatment of sodium molybdate with anthranilic acid and 2,6-Prⁱ₂C₆H₃NH₂ in a 1 : 1 ratio afforded [NEt₃H][MoCl₃{2-(HN)C₆H₄CO ₂}(NC₆H₃Prⁱ₂-2,6)] 4. Products of reactions of sodium molybdate with the amino acid 2,2-diphenylglycine and 2-aminoterephthalic acid, namely [NEt₃H][Mo-Cl₃(NCHPh₂)(H₂NCPh ₂CO₂)] 5 and [NEt₃H][MoCl₃{2-HNC₆H₃CO ₂(CO₂H)-1,4} {2-NC₆H₃(CO₂H)₂-1,4}] 6 respectively are also reported. Complexes 1 to 6 have been structurally characterised; all contain pseudo-octahedral geometries about the metal centre, and all except 3 are salts in which the anion contains a mer arrangement of chloride ligands.

Full text of DOI:10.1039/a701502j

View Article Online / Journal Homepage / Table of Contents for this issue
Synthesis and characterisation of molybdenum complexes bearing
highly functionalised imido substituents†
Vernon C. Gibson,*,a Carl Redshaw,a William Cleggb and Mark R. J. Elsegoodb
a
Department of Chemistry, Imperial College, South Kensington, London, UK SW7 2AY
b Department of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne,
UK NE1 7RU
The monofunctionalised anilines 2-(H2N)C6H4X (where X = CO2H, SO3H, or CN) reacted with sodium molybdate
in the presence of NEt3 and SiMe3Cl in refluxing dme (1,2-dimethoxyethane) to give [NEt3H][MoCl3-
{2-(HN)C6H4CO2}{2-Me3SiO2CC6H4N}] 1, [NEt3H]2[MoCl3{2-NC6H4SO3}{2-(HN)C6H4SO3}] 2 and [MoCl2-
(2-NCC6H4N)2(dme)] 3. Treatment of sodium molybdate with anthranilic acid and 2,6-Pri2C6H3NH2 in a 1:1
ratio afforded [NEt3H][MoCl3{2-(HN)C6H4CO2}(NC6H3Pri2-2,6)] 4. Products of reactions of sodium molybdate
with the amino acid 2,2-diphenylglycine and 2-aminoterephthalic acid, namely [NEt3H][Mo-
Cl3(NCHPh2)(H2NCPh2CO2)] 5 and [NEt3H][MoCl3{2-HNC6H3CO2(CO2H)-1,4}{2-NC6H3(CO2H)2-1,4}] 6
respectively are also reported. Complexes 1 to 6 have been structurally characterised; all contain pseudo-
octahedral geometries about the metal centre, and all except 3 are salts in which the anion contains a mer
arrangement of chloride ligands.
The reaction of ammonium 1 or sodium 2 molybdate with
amines or anilines in the presence of trimethylsilyl chloride and
OSiMe3
–
SO3
a sacrificial base (typically triethylamine) is commonly utilised
O
as a convenient ‘one pot’ entry into bis(imido)molybdenum
chemistry. Schrock and co-workers3 have shown that the meth-
odology may be extended to arylimido complexes bearing func-
tionalities such as Br, CF3 and CN (para position). We became
interested in establishing whether or not the molybdate reaction
conditions could also be applied to the synthesis of imido
complexes bearing highly functional substituents, e.g. CO2H
and SO3H, groups that ordinarily would also be expected to
get involved in metal complexation. Here, we describe a series
of products (Scheme 1) arising from treatment of sodium
molybdate with functionalised anilines all of which bear
molybdenum-bound imido groups. Crystal structure analyses
of the products have facilitated an understanding of the co-
ordination patterns arising in these highly functionalised imido
species. These results encouraged us to try an amino acid under
the molybdate preparation conditions and a yet more highly
functionalised aniline, containing two carboxylic acid substitu-
ents. The products from these reactions have also been structur-
ally characterised. A number of organoimidorhenium() com-
plexes containing a ligand derived from glycine have recently
been reported.4 The only other example of an organoimido
group functionalised with a carboxylic acid group is the rather
poorly characterised [ReCl(OEt)(PPh3)2(NC6H4CO2)].5
N
Mo
O
N
Mo
O
Cl
Cl
N
H
H
–
–
Cl
N
Cl
Cl
Cl
S
O
O
O
1
2
NC
N
Cl
N
Mo
O
Cl
H
O
–
Mo
Cl
Cl
N
O
N
Cl
NC
O
3
4
HO2C
Ph
OH
Ph
H
Results and Discussion
O
N
Mo
O
N
2-(H2N)C6H4X derivatives
Cl
Cl
NH2
H
The reaction of Na2MoO4 with 2 equivalents of anthranilic
acid, 2-(H2N)C6H4CO2H, in the presence of NEt3 and SiMe3Cl
in refluxing dme (1,2-dimethoxyethane) afford after work-up
the highly crystalline salt [NEt3H][MoCl3{2-(HN)C6H4CO2}{2-
Me3SiO2CC6H4N}] 1, in 27% isolated yield. A structural repre-
sentation of the anion in 1 is shown in Scheme 1. Crystals
suitable for an X-ray study were grown from acetonitrile. Fig. 1
shows the mer-trichloro pseudo-octahedral geometry of 1; bond
lengths and angles are collected in Table 1. The main distortion
–
–
Cl
Cl
N
Cl
Mo
O
Cl
Ph
Ph
CO2H
O
O
6
5
Scheme 1
arises from the bite angle of the chelating amidobenzoate ligand
[81.81(14)Њ]. A trans influence is exerted by the amido ligand,
Mo᎐Cl(2) 2.4214(12) Å; the mutually trans Mo᎐Cl distances are
† Dedicated to the memory of Professor Sir Geoffrey Wilkinson.
J. Chem. Soc., Dalton Trans., 1997, Pages 3207–3212
3207

View Article Online
Fig. 1 Molecular structure of complex 1, without C᎐H hydrogen
atoms and showing hydrogen bonding
Fig. 3 Molecular structure of complex 3; details as in Fig. 1
Table 2 Selected bond lengths (Å) and angles (Њ) for complex 2
Mo᎐N(1)
Mo᎐N(2)
Mo᎐Cl(2)
N(1)᎐C(1)
S(1)᎐O(2)
N(2)᎐C(7)
S(2)᎐O(5)
1.943(3)
1.717(3)
2.4198(10)
1.397(5)
1.436(3)
1.390(5)
1.458(3)
Mo᎐O(1)
Mo᎐Cl(1)
Mo᎐Cl(3)
S(1)᎐O(1)
S(1)᎐O(3)
S(2)᎐O(4)
S(2)᎐O(6)
2.177(3)
2.4153(11)
2.3725(11)
1.484(3)
1.446(3)
1.459(3)
1.436(3)
N(2)᎐Mo᎐N(1)
N(1)᎐Mo᎐O(1)
N(1)᎐Mo᎐Cl(3)
N(2)᎐Mo᎐Cl(1)
O(1)᎐Mo᎐Cl(1)
N(2)᎐Mo᎐Cl(2)
O(1)᎐Mo᎐Cl(2)
Cl(1)᎐Mo᎐Cl(2)
S(1)᎐O(1)᎐Mo
93.67(15)
82.57(12)
98.35(11)
93.48(11)
84.12(8)
99.35(11)
84.16(7)
84.32(4)
131.9(2)
N(2)᎐Mo᎐O(1)
N(2)᎐Mo᎐Cl(3)
O(1)᎐Mo᎐Cl(3)
N(1)᎐Mo᎐Cl(1)
Cl(3)᎐Mo᎐Cl(1)
N(1)᎐Mo᎐Cl(2)
Cl(3)᎐Mo᎐Cl(2)
C(1)᎐N(1)᎐Mo
C(7)᎐N(2)᎐Mo
175.56(13)
96.25(11)
86.67(8)
89.00(11)
167.39(4)
165.68(11)
86.19(4)
Fig. 2 Molecular structure of complex 2; details as in Fig. 1
Table 1 Selected bond lengths (Å) and angles (Њ) for complex 1
138.1(3)
171.3(3)
Mo᎐N(1)
Mo᎐N(2)
Mo᎐Cl(2)
N(1)᎐C(1)
C(7)᎐O(1)
C(14)᎐O(4)
1.929(4)
1.728(4)
2.4214(12)
1.376(6)
1.278(5)
1.208(6)
Mo᎐O(1)
Mo᎐Cl(1)
Mo᎐Cl(3)
C(7)᎐O(2)
N(2)᎐C(8)
C(14)᎐O(3)
2.113(3)
2.4045(14)
2.4025(13)
1.242(5)
1.390(5)
1.332(5)
figuration of chlorines all of which are mutually cis to the orga-
noimido function. In contrast to 1, the ortho-acid group on the
imido ligand has not been attacked by SiMe3Cl and retains a
uninegative charge. There are hydrogen bonds from both
cations and from the N᎐H group of the chelating ligand to
sulfonate oxygen atoms.
N(2)᎐Mo᎐N(1)
N(1)᎐Mo᎐O(1)
N(1)᎐Mo᎐Cl(3)
N(2)᎐Mo᎐Cl(1)
O(1)᎐Mo᎐Cl(1)
N(2)᎐Mo᎐Cl(2)
O(1)᎐Mo᎐Cl(2)
Cl(1)᎐Mo᎐Cl(2)
C(7)᎐O(1)᎐Mo
94.4(2)
81.84(14)
98.38(13)
97.46(13)
85.68(10)
97.69(12)
86.37(9)
83.65(5)
135.9(3)
N(2)᎐Mo᎐O(1)
N(2)᎐Mo᎐Cl(3)
O(1)᎐Mo᎐Cl(3)
N(1)᎐Mo᎐Cl(1)
Cl(3)᎐Mo᎐Cl(1)
N(1)᎐Mo᎐Cl(2)
Cl(3)᎐Mo᎐Cl(2)
C(1)᎐N(1)᎐Mo
C(8)᎐N(2)᎐Mo
175.1(2)
92.98(13)
84.49(9)
89.31(13)
166.53(4)
166.69(12)
86.55(4)
135.8(3)
170.6(3)
Treatment of Na2MoO4 with 2-cyanoaniline at 80 ЊC in
MeCN affords after work-up the bis(imido)molybdenum prod-
uct [MoCl2(2-NCC6H4N)2(dme)] 3. The structure of one of the
two crystallographically independent molecules of 3 is shown in
Fig. 3; important bond lengths and angles are given in Table 3.
The molecular geometry is octahedral with trans chlorines and
cis imido groups. The N(1)᎐Mo(1)᎐N(3) angle is opened up to
104.1(2)Њ and the Cl(1)᎐Mo(1)᎐Cl(2) angle is reduced to
159.71(5)Њ from ideal octahedral values. The four Mo᎐N dis-
tances for the two molecules are all approximately equal at
1.736(4)–1.752(4) Å, but the range of Mo᎐N᎐C angles [155.2(3)
to 169.8(3)Њ] reflects the ready deviation of this angle from
linearity. Clearly, the ortho-cyano groups do not interact with
the metal centre in any way.
The simultaneous addition of the two amines 2-
(H2N)C6H4CO2H and 2,6-Pri2C6H3NH2 to a stirred suspension
of Na2MoO4 in dme under similar conditions affords after
work-up the highly crystalline salt [NEt3H][MoCl3{2-
(HN)C6H4CO2}(NC6H3Pri2-2,6)] 4 in good yield. The IR and
NMR data (see Experimental section) are consistent with this
formulation. Crystals suitable for an X-ray study were grown
from acetonitrile. Fig. 4 depicts the mer-trichloro pseudo-
octahedral geometry of 4 (see Scheme 1 for a simplified struc-
tural representation of the anion). Bond lengths and angles are
collected in Table 4. The main distortion arises from the bite
angle of the chelating amidobenzoate ligand [83.75(9)Њ]. A trans
influence is exerted by the amido ligand with Mo᎐Cl(2) rather
longer than the other two Mo᎐Cl bonds. The carboxylate group
ca. 0.02 Å shorter. The carboxylate group of this chelating
ligand is trans to a near-linear imido group, Mo᎐N(2)᎐C(8)
170.6(3)Њ, which is acting as a four-electron (neutral) donor
[Mo᎐N(2) 1.728(4) Å]. Interestingly, the ortho-acid group of
this organoimido ligand has been attacked by SiMe3Cl resulting
in the formation of a silyl ester group. There is hydrogen bond-
ing between the O(4) atom of the silyl ester group and the amide
proton of the amidobenzoate chelate, and also between the
cation Et3NHϩ and O(2) of the chelating ligand.
A similar reaction of Na2MoO4 with the sulfonic acid 2-
(H2N)C6H4SO3H in refluxing dme afforded after work-up large
red needles in 36% isolated yield. Spectroscopic data on this
product 2 were not consistent with a simple bis(imido)molyb-
denum type complex, and hence its structure was determined by
X-ray diffraction. The structure is shown in Fig. 2 and a repre-
sentation of the anionic component is depicted in Scheme 1.
Selected bond lengths and angles are given in Table 2. Again the
molecule has a very similar pseudo-octahedral geometry with a
chelating amidobenzenesulfonate type ligand and a mer con-
3208
J. Chem. Soc., Dalton Trans., 1997, Pages 3207–3212

View Article Online
Table 3 Selected bond lengths (Å) and angles (Њ) for complex 3
Table 4 Selected bond lengths (Å) and angles (Њ) for complex 4
Mo(1)᎐N(1)
Mo(1)᎐O(1)
Mo(1)᎐Cl(1)
N(1)᎐C(1)
Mo(2)᎐N(5)
Mo(2)᎐O(3)
Mo(2)᎐Cl(3)
N(5)᎐C(19)
1.752(4)
2.312(3)
2.3943(12)
1.379(6)
1.752(4)
2.298(3)
2.3846(12)
1.385(6)
Mo(1)᎐N(3)
Mo(1)᎐O(2)
Mo(1)᎐Cl(2)
N(3)᎐C(8)
Mo(2)᎐N(7)
Mo(2)᎐O(4)
Mo(2)᎐Cl(4)
N(7)᎐C(26)
1.742(4)
2.337(3)
2.3864(11)
1.391(5)
1.736(4)
2.320(3)
2.4069(12)
1.387(6)
Mo᎐N(1)
Mo᎐O(1)
Mo᎐Cl(2)
N(1)᎐C(1)
C(19)᎐O(1)
1.740(2)
2.099(2)
2.4503(8)
1.384(4)
1.283(4)
Mo᎐N(2)
Mo᎐Cl(1)
Mo᎐Cl(3)
N(2)᎐C(13)
C(19)᎐O(2)
1.937(2)
2.4280(8)
2.3837(8)
1.397(3)
1.229(4)
N(1)᎐Mo᎐N(2)
N(2)᎐Mo᎐O(1)
N(2)᎐Mo᎐Cl(3)
N(1)᎐Mo᎐Cl(1)
O(1)᎐Mo᎐Cl(1)
N(1)᎐Mo᎐Cl(2)
O(1)᎐Mo᎐Cl(2)
Cl(1)᎐Mo᎐Cl(2)
C(13)᎐N(2)᎐Mo
94.55(10)
83.75(9)
98.64(7)
97.86(8)
85.82(7)
97.65(8)
84.50(6)
83.47(3)
133.0(2)
N(1)᎐Mo᎐O(1)
N(1)᎐Mo᎐Cl(3)
O(1)᎐Mo᎐Cl(3)
N(2)᎐Mo᎐Cl(1)
Cl(3)᎐Mo᎐Cl(1)
N(2)᎐Mo᎐Cl(2)
Cl(3)᎐Mo᎐Cl(2)
C(1)᎐N(1)᎐Mo
C(19)᎐O(1)᎐Mo
175.91(10)
93.92(8)
82.69(7)
88.23(7)
165.86(3)
166.07(7)
87.24(3)
177.8(2)
134.7(2)
N(3)᎐Mo(1)᎐N(1)
N(1)᎐Mo(1)᎐O(1)
N(1)᎐Mo(1)᎐O(2)
N(3)᎐Mo(1)᎐Cl(2)
O(1)᎐Mo(1)᎐Cl(2)
N(3)᎐Mo(1)᎐Cl(1)
O(1)᎐Mo(1)᎐Cl(1)
104.1(2)
91.1(2)
N(3)᎐Mo(1)᎐O(1)
N(3)᎐Mo(1)᎐O(2)
O(1)᎐Mo(1)᎐O(2)
N(1)᎐Mo(1)᎐Cl(2)
O(2)᎐Mo(1)᎐Cl(2)
N(1)᎐Mo(1)᎐Cl(1)
O(2)᎐Mo(1)᎐Cl(1)
C(1)᎐N(1)᎐Mo(1)
N(7)᎐Mo(2)᎐N(5)
N(5)᎐Mo(2)᎐O(3)
N(5)᎐Mo(2)᎐O(4)
N(7)᎐Mo(2)᎐Cl(3)
O(3)᎐Mo(2)᎐Cl(3)
N(7)᎐Mo(2)᎐Cl(4)
O(3)᎐Mo(2)᎐Cl(4)
164.72(15)
94.22(15)
70.50(11)
99.93(13)
82.21(9)
92.91(13)
80.63(9)
158.4(3)
161.0(2)
97.69(13)
80.98(9)
94.30(13)
83.14(9)
Cl(2)᎐Mo(1)᎐Cl(1) 159.71(5)
C(8)᎐N(3)᎐Mo(1)
N(7)᎐Mo(2)᎐O(3)
N(7)᎐Mo(2)᎐O(4)
O(3)᎐Mo(2)᎐O(4)
N(5)᎐Mo(2)᎐Cl(3)
O(4)᎐Mo(2)᎐Cl(3)
N(5)᎐Mo(2)᎐Cl(4)
O(4)᎐Mo(2)᎐Cl(4)
166.5(3)
104.3(2)
Table 5 Selected bond lengths (Å) and angles (Њ) for complex 5
164.13(14)
93.38(14)
70.78(11)
100.10(13)
82.96(9)
91.41(15)
161.42(15)
97.85(12)
81.56(10)
94.05(12)
82.75(9)
Mo᎐O(1)
Mo᎐N(2)
Mo᎐Cl(2)
N(1)᎐C(2)
O(2)᎐C(1)
2.1266(13)
1.719(2)
2.3972(5)
1.508(2)
1.231(2)
Mo᎐N(1)
Mo᎐Cl(1)
Mo᎐Cl(3)
O(1)᎐C(1)
N(2)᎐C(16)
2.221(2)
2.3750(5)
2.4256(5)
1.277(2)
1.449(2)
91.93(13)
80.86(9)
Cl(3)᎐Mo(2)᎐Cl(4) 160.42(5)
C(26)᎐N(7)᎐Mo(2) 169.8(3)
C(19)᎐N(5)᎐Mo(2) 155.2(3)
N(2)᎐Mo᎐O(1)
O(1)᎐Mo᎐N(1)
O(1)᎐Mo᎐Cl(1)
N(2)᎐Mo᎐Cl(2)
N(1)᎐Mo᎐Cl(2)
N(2)᎐Mo᎐Cl(3)
N(1)᎐Mo᎐Cl(3)
Cl(2)᎐Mo᎐Cl(3)
C(1)᎐O(1)᎐Mo
166.20(6)
74.54(5)
90.45(4)
94.99(5)
86.86(5)
95.41(5)
85.67(5)
167.36(2)
123.15(11)
N(2)᎐Mo᎐N(1)
N(2)᎐Mo᎐Cl(1)
N(1)᎐Mo᎐Cl(1)
O(1)᎐Mo᎐Cl(2)
Cl(1)᎐Mo᎐Cl(2)
O(1)᎐Mo᎐Cl(3)
Cl(1)᎐Mo᎐Cl(3)
C(2)᎐N(1)᎐Mo
C(16)᎐N(2)᎐Mo
91.67(7)
103.34(5)
164.98(4)
84.79(4)
92.33(2)
83.39(4)
92.24(2)
115.82(11)
166.93(13)
Fig. 4 Molecular structure of complex 4; details as in Fig. 1
of this chelating ligand is trans to a near-linear arylimido
group, Mo᎐N(1)᎐C(1) 177.8(2)Њ, which is acting as a four-
electron donor [Mo᎐N(1) 1.740(2) Å]. There is a bifurcated
hydrogen bond between the cation Et3NHϩ and Cl(1) and Cl(2).
Additionally, the anions are linked together in chains by hydro-
gen bonding between the N᎐H of the chelate ligand in each
anion and carboxylate O(2) of an adjacent anion.
Fig. 5 Molecular structure of complex 5; details as in Fig. 1
after work-up red prisms of complex 6 in 32% isolated yield. As
expected, the IR spectrum contains strong stretches in the
Amino acid derivatives
ν(C᎐O) region together with sharp bands in the ν(N᎐H) region.
᎐
Treatment of Na2MoO4 with 2,2-diphenylglycine at elevated
temperature in dme in the presence of NEt3 and SiMe3Cl
affords after work-up large turquoise prisms of complex 5 in
A single-crystal structure determination revealed disorder in
the ligands, the cation and the dme solvent. Nevertheless, the
overall identification of the complex and definition of the co-
ordination geometry at molybdenum are clear (Fig. 6, Scheme
1, Table 6).
good yield. The IR spectrum contains strong stretches in the
1
ν(N᎐H) and ν(C᎐O) regions; the H NMR spectrum is broad
᎐
and uninformative. A single-crystal X-ray analysis of 5 reveals
The co-ordination geometry can thus be described as octa-
hedral with distortion caused by the restricted bite angle of the
chelating amidobenzoate ligand. The O(2) atom of this ligand
is involved in hydrogen bonding to the cation Et3NHϩ. The
amide proton on N(1) is hydrogen bonded to the O(5) atom of
the carboxylate group on the near linear organoimido ligand
[Mo᎐N(2)᎐C(9) 167.2(3)Њ]. Further hydrogen bonding links
anions in pairs via the commonly observed type of centrosym-
metric double hydrogen bonding of carboxylic acids, here
involving O(3) and O(4), and then into chains by a weaker
interaction from O(7)᎐H to Cl(3) on an adjacent anion.
an octahedral geometry with meridional chlorines, which are all
mutually cis to an organoimido ligand (᎐NCHPh ) derived
᎐
2
from decarboxylation of diphenylglycine (Fig. 5, Table 5). A
second intact diphenylglycine chelates as an aminocarboxylate
to the molybdenum centre and is hydrogen bonded through
O(2) to the triethylammonium counter ion.
2-Aminoterephthalic acid
Treatment of Na2MoO4 with
2
equivalents of 2-
aminoterephthalic acid under analogous conditions affords
J. Chem. Soc., Dalton Trans., 1997, Pages 3207–3212
3209

View Article Online
Table 6 Selected bond lengths (Å) and angles (Њ) for complex 6ؒdme
Mo᎐N(1)
Mo᎐N(2)
Mo᎐Cl(2)
N(1)᎐C(1)
C(7)᎐O(2)
C(8)᎐O(4)
C(15)᎐O(5)
C(16)᎐O(7)
1.925(4)
1.720(3)
2.3922(14)
1.380(5)
1.250(10)
1.292(10)
1.202(5)
1.292(13)
Mo᎐O(1)
2.093(3)
Mo᎐Cl(1)
Mo᎐Cl(3)
C(7)᎐O(1)
C(8)᎐O(3)
N(2)᎐C(9)
C(15)᎐O(6)
C(16)᎐O(8)
2.4121(13)
2.4406(13)
1.220(10)
1.223(11)
1.384(5)
1.319(5)
1.256(13)
N(2)᎐Mo᎐N(1)
N(1)᎐Mo᎐O(1)
N(1)᎐Mo᎐Cl(2)
N(2)᎐Mo᎐Cl(1)
O(1)᎐Mo᎐Cl(1)
N(2)᎐Mo᎐Cl(3)
O(1)᎐Mo᎐Cl(3)
Cl(1)᎐Mo᎐Cl(3)
C(7)᎐O(1)᎐Mo
93.81(16)
82.19(16)
87.95(12)
96.93(12)
87.74(12)
89.56(12)
83.02(11)
87.49(5)
N(2)᎐Mo᎐O(1)
N(2)᎐Mo᎐Cl(2)
O(1)᎐Mo᎐Cl(2)
N(1)᎐Mo᎐Cl(1)
Cl(2)᎐Mo᎐Cl(1)
N(1)᎐Mo᎐Cl(3)
Cl(2)᎐Mo᎐Cl(3)
C(1)᎐N(1)᎐Mo
C(9)᎐N(2)᎐Mo
171.06(17)
98.62(13)
89.26(11)
168.46(12)
86.29(5)
96.82(12)
170.26(4)
133.2(4)
Fig. 6 Molecular structure of complex 6; details as in Fig. 1
R
N
139.1(6)
167.2(3)
Cl
H
N
Cl
Cl
Mo
C, 42.7; H, 5.3; N, 6.5%). IR: 3185w, 1676w, 1639w, 1587w,
1557w, 1309s, 1279s, 1255s, 1196w, 1150w, 1094w, 1033w, 981w,
X
1
942w, 908w, 838m, 760s, 686w, 662w, 643w and 609w cmϪ1. H
I
NMR (C6D6, 300 MHz, 298 K): δ 15.61 (br s, 1 H, NH), 9.86
(br s, 1 H, Et3NH), 8.32–6.61 (9 × m, 8 H, aryl), 3.14 (m, 6 H,
CH3CH2N), 1.26 (m, 9 H, CH3CH2N) and 0.05 (s, 9 H. Me3Si).
In conclusion, molybdenum imido complexes bearing highly
functionalised substituents can be prepared conveniently in
moderate yields via the ‘molybdate route’. Instead of affording
bis(imido)molybdenum products, our results show that anionic
monoimido complexes are favoured in most cases, with intra-
molecular and/or interionic hydrogen-bonding interactions.
The X-ray crystallographic studies reveal a common structural
motif (I) for the anions of these salts. It is noted that a closely
related motif has been seen in hydrazido(2Ϫ) products arising
from the molybdate reaction.6
[NEt3H]2[MoCl3{2-NC6H4SO3}{2-(HN)C6H4SO3}] 2. As
above using NEt3 (8.1 cm3, 58.1 mmol), SiMe3Cl (14.9 cm3,
117.4 mmol), Na2MoO4 (3.0 g, 14.6 mmol) and 2-(H2N)-
C6H4SO3H (5.1 g, 29.4 mmol) in dme (100 cm3). Recrystallis-
ation from MeCN gave large red needles of complex 2 (yield
3.9 g, 36%) (Found: C, 39.9; H, 6.1; N, 7.6. Calc. for C24H41-
Cl3MoN4O6S2: C, 38.5; H, 5.5; N, 7.5%). IR: 3337 (br), 3084w,
2625w, 2531w, 1571w, 1270s, 1259s, 1170s, 1158s, 1140s, 1082s,
1036s, 1019s, 1011s, 989s, 967m, 917m, 873w, 851w, 837w, 808w,
776s, 732m, 722s, 679w, 657m, 617s, 595m, 572m, 548m, 538m,
Experimental
1
511w, 477w and 463w cmϪ1. NMR (CDCl3, 298 K): H (300
General
MHz), δ 16.49 (s, 1 H, NH), 10.63 (br s, 2 H, Et3NH), 8.02–7.14
(6 × m, 8 H, aryl), 3.07 (m, 12 H, CH3CH2N) and 1.29 (m, 18
H, CH3CH2N); 13C (75.0 MHz), δ 149.6, 132.16, 131.73, 130.60,
130.39, 128.15, 121.79, 46.40 and 8.89.
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 Departments of Chemistry at
Durham, Imperial College and Medac Ltd. The NMR spectra
were recorded on a Varian VXR 400 S spectrometer at 400.0
(1H) and 75.0 MHz (13C) and, where stated, a Bruker DRX 300
machine (1H, 300 MHz); chemical shifts are referenced to the
residual protio impurity of the deuteriated solvent. The ESR
spectra were recorded on a Varian E-12 (X-band) spectrometer.
Infrared spectra (Nujol mulls, KBr windows) were obtained
on Perkin-Elmer 577 and 457 grating spectrophotometers. All
chemicals were obtained commercially and used as received
unless stated otherwise.
[MoCl2(2-NCC6H4N)2(dme)] 3. As above using NEt3 (8.1 cm3,
58.1 mmol), SiMe3Cl (14.9 cm3, 117.4 mmol), Na2MoO4 (3.0 g,
14.6 mmol) and 2-cyanoaniline (3.45 g, 29.2 mmol) in MeCN
(100 cm3). Extraction into hot dme (ca. 80 cm3) afforded red
needles, which were washed twice with cold diethyl ether (ca.
2 × 30 cm3) and dried in vacuo. Yield 4.2 g, 59% (Found: C,
44.8; H, 6.0; N, 10.9. Calc. for C18H18Cl2MoN4O2: C, 44.2; H,
6.5; N, 11.4%). IR: 2361w, 2342w, 2227w, 1935w, 1732w, 1715w,
1624w, 1606w, 1563m, 1306m, 1262s, 1183w, 1156m, 1101s,
1085s, 1037s, 975m, 882w, 864m, 801s, 775m, 761m, 723m,
1
660w, 616w and 591w cmϪ1. H NMR (CDCl3, 300 MHz, 298
K): δ 8.23–6.73 (several m, 8 H, aryl) and 4.05 (br s, 10 H,
dme).
Preparations
[NEt3H][MoCl3{2-(HN)C6H4CO2}(NC6H3Pri2-2,6)] 4. As
above using NEt3 (8.1 cm3, 58.1 mmol), SiMe3Cl (14.9 cm3, 117.4
mmol), anthranilic acid (2.0 g, 14.6 mmol), 2,6-Pri2C6H3NH2
(2.77 cm3, 14.7 mmol) and Na2MoO4 (3.0 g, 14.6 mmol) in dme
(100 cm3). Extraction into warm MeCN (ca. 80 cm3) afforded
red-purple prisms. Yield 4.0 g. Further crops can be obtained
from the mother-liquor. Overall yield 6.1 g, 61% (Found: C,
49.4; H, 6.3; N, 8.4. Calc. for C25H38Cl3MoN3O2ؒMeCN: C,
49.4; H, 6.3, N, 8.5%). IR: 3495w, 3466w, 3438w, 3372w, 2335w,
1963w, 1756w, 1599s, 1561s, 1349s, 1303m, 1260m, 1228m,
1152m, 1104w, 1058w, 1029w, 917w, 886w, 835w, 805w, 764w,
724w, 690w, 657w, 504w, 464w and 429w cmϪ1. NMR (CDCl3,
[NEt3H][MoCl3{2-(HN)C6H4CO2}{2-Me3SiO2CC6H4N}] 1.
Triethylamine (13.6 cm3, 97.6 mmol) and SiMe3Cl (24.7 cm3,
194.6 mmol) were added to Na2MoO4 (5.0g, 24.3 mmol) in dme
(150 cm3). Anthranilic acid (6.66 g, 48.6 mmol) in dme (ca. 40
cm3) was added and the reaction mixture refluxed for 12 h
affording a purple solution and a white precipitate. The solu-
tion was filtered from the solid which was then washed with
dme (2 × 50 cm3). The solvent was then removed from the com-
bined washings under reduced pressure. Recrystallisation from
hot MeCN gave complex 1 as purple prisms. Yield 4.2 g, 27%
(Found: C, 43.5; H, 5.5; N, 6.6. Calc. for C23H34Cl3MoN3O4Si:
3210
J. Chem. Soc., Dalton Trans., 1997, Pages 3207–3212

Table 7 Crystallographic data for compounds 1–6
1
2
3
4
5
6ؒdme
Formula
[C6H16N][C17H18Cl3MoN2O4Si]
[C6H16N]2[C12H9Cl3
MoN2O6S2]
748.0
C18H18Cl2MoN4O2
[C6H16N][C19H22Cl3MoN2O2]
[C6H16N][C27H23Cl3MoN2O2]
[C6H16N][C16H10Cl3MoN2O8]ؒ
C4H10O2
752.9
M
646.9
489.2
614.9
712.0
Crystal system
Space group
a/Å
b/Å
c/Å
Triclinic
P1
Monoclinic
P21/n
9.1981(8)
25.526(2)
13.9711(12)
Monoclinic
P21 /c
24.565(2)
8.1609(6)
22.507(2)
Orthorhombic
Pbca
13.0324(10)
19.0035(15)
24.128(2)
Triclinic
P1
Monoclinic
P21 /n
9.2009(5)
33.4055(18)
10.8259(6)
¯
¯
10.1216(11)
10.9746(12)
15.302(2)
69.015(2)
84.755(2)
67.205(2)
1460.9(3)
2
10.9433(8)
11.4974(8)
14.4936(11)
92.152(2)
104.879(2)
107.558(2)
1667.2(2)
2
α/Њ
β/Њ
92.036(2)
116.666(2)
100.771(2)
γ/Њ
U/Å3
3278.2(5)
4
1.516
4032.0(5)
8
1.612
5975.5(8)
8
1.367
3268.8(3)
4
1.530
Z
Dc /g cmϪ3
1.471
0.80
1.418
0.67
µ/mmϪ11
0.81
0.94
0.73
0.70
F (000)
664
1544
1968
2544
734
1544
Crystal size/mm
θmax /Њ
0.35 × 0.18 × 0.08
25.6
0.20 × 0.19 × 0.08
26.0
0.67 × 0.23 × 0.12
26.4
0.40 × 0.34 × 0.26
28.6
0.62 × 0.57 × 0.54
28.3
0.35 × 0.25 × 0.14
25.0
Maximum indices hkl
Reflections measured
Unique reflections
Rint
12, 13, 18
12720
4809
12, 32, 18
18636
6436
30, 9, 28
21 008
7949
17, 24, 32
35 187
7140
13, 14, 19
10 261
7140
12. 44. 14
16 922
5721
0.0528
0.0488
0.0640
0.0561
0.0261
0.0282
Transmission
Extinction coefficient x
Weighting parameters a, b
No. refined parameters
wR2 (all data)
R1 (‘observed’ data)
Goodness of fit
Maximum, minimum
electron density/e ÅϪ3
0.779–0.913
0.0026(4)
0.0070, 4.2304
329
0.1022
0.0504 (4269)
1.167
0.776–0.937
0.000 80(15)
0.0214, 8.0491
414
0.1049
0.0474 (5161)
1.208
0.552–0.962
0.0017(2)
0.0576, 12.1678
492
0.1412
0.0530 (6970)
1.192
0.775–0.824
0.000 66(5)
0.0135, 9.0399
315
0.0873
0.0501 (5661)
1.223
0.658–0.693
0.0034(5)
0.0385, 1.3171
389
0.0838
0.0314 (6935)
1.142
0.787–0.901
0.0017(3)
0.0564, 8.2943
618
0.1347
0.0515 (4644)
1.084
0.47, Ϫ0.68
1.27, Ϫ0.47
1.37. Ϫ1.37
0.42, Ϫ0.53
0.62, Ϫ1.23
0.84, Ϫ0.98

View Article Online
1
298 K): H (400 MHz), δ 12.52 (s, 1 H, NH), 11.04 (br s, 1 H,
restraints; for the dme molecule no sensible geometry could be
Et3NH), 8.27 (d, 1 H, JH H = 7.6, aryl), 7.44–7.04 (several m, 4
H, aryl), 6.63 (d, 1 H, JH H = 8.4, aryl), 4.55 (spt, 2 H, JH H = 6.8,
CHCMe2), 3.33 (m, 6 H, CH3CH2N), 1.94 (s, 3 H, CH3CN),
1.32 [d, 12 H, JH H = 6.8 Hz, (CH3)2CH] and 1.31 (m, 9 H,
CH3CH2N, JH H obscured); 13C-{1H}, δ 169.47, 153.56, 151.92,
149.48, 132.99, 131.94, 131.29, 130.97, 126.82, 123.61, 121.16,
45.93, 28.23, 25.47 and 8.82.
found, and the disorder model consisted of eleven partially
occupied sites, all treated as carbon. Anisotropic displacement
parameters were refined for non-hydrogen atoms. Hydrogen
atoms were made to ride on the atoms to which they were
attached, except for free refinement of the N᎐H groups in the
ligands, which (together with most of the other H atoms) were
revealed in difference electron-density maps.
A pseudo-
orthorhombic A-centred unit cell can be generated for the
structure of 3, by the transformation (0 1 0 / 0 0 Ϫ 1 /
Ϫ 2 0 Ϫ 1); this gives a value of over 0.5 for Rint, however, and
one of the cell angles is 89.4Њ, so the true symmetry is mono-
clinic as reported. The two independent molecules are related
by an approximate non-crystallographic inversion centre with
coordinates close to (0.25, 0.51, 0.33). Residual indices are
[NEt3H][MoCl3(NCHPh2)(H2NCPh2CO2)] 5. As above using
NEt3 (2.7 cm3, 19.4 mmol), SiMe3Cl (5.0 cm3, 39.4 mmol),
Na2MoO4 (1.0 g, 4.9 mmol) and 2,2-diphenylglycine (2.3 g, 10.1
mmol) in dme (50 cm3). Extraction into hot MeCN (ca. 40 cm3)
afforded turquoise prisms of complex 5. Yield 1.24 g, 62%
(Found: C, 55.5; H, 6.0; N, 6.3. Calc. for C33H38Cl3MoN3O2: C,
55.7; H, 5.4; N, 5.9%). IR: 3329w, 3273w, 2670w, 2609w, 2498w,
1631s, 1558m, 1264m, 1227m, 1168w, 1135m, 1060w, 1029w,
1014m, 920w, 822m, 779w, 735w, 679w and 632w cmϪ1. EPR
(solid, 298 K): giso 1.953.
2
2
2
2 2 ¹
²
defined as wR2 = [Σw(Fo Ϫ Fc ) /Σw(Fo ) ] for all data, con-
2
ventional R = Σ Fo| Ϫ |Fc /Σ|Fo| for reflections with Fo
>
2
2σ(Fo ); the goodness of fit was calculated on all F 2 values.
Atomic coordinates, displacement parameters, and bond
lengths and angles have been deposited at the Cambridge
Crystallographic Data Centre (CCDC). See Instructions for
Authors, J. Chem. Soc., Dalton Trans., 1997, Issue 1. Any
request to the CCDC for this material should quote the full
literature citation and the reference number 186/559.
[NEt3H][MoCl3{2-HNC6H3CO2(CO2H)-1,4}{2-NC6H3(CO2-
H)2-1,4}] 6. As above using NEt3 (8.1 cm3, 58.3 mmol),
SiMe3Cl (14.8 cm3, 116.5 mmol), Na2MoO4 (3.0 g, 14.6 mmol)
and 2-aminoterephthalic acid (5.28 g, 29.2 mmol). The crystals
were dried in vacuo overnight to remove dme solvent of crystal-
lisation. Yield 3.1 g, 32% (Found: C, 39.9; H, 4.4; N, 5.3. Calc.
for C22H28Cl3MoN3O8: C, 39.8; H, 4.3; N, 6.3%). IR: 3383m,
1681s, 1622s, 1591s, 1553m, 1495m, 1300s, 1261s, 1230s, 1156s,
1093s, 1053s, 1020s, 944m, 908m, 839w, 801s, 753s, 723s, 684w,
Acknowledgements
The Engineering and Physical Sciences Research Council is
thanked for financial support.
665w, 647w, 567w, 558w, 519w, 485w, 647w and 427w cmϪ1
.
References
X-Ray crystallography
1 H. H. Fox, K. B. Yap, J. Robbins, S. Cai and R. R. Schrock, Inorg.
Chem., 1992, 31, 2287.
2 P. W. Dyer, V. C. Gibson, J. A. K. Howard, B. Whittle and C. Wilson,
J. Chem. Soc., Chem. Commun., 1992, 1666.
3 J. H. Oskam, H. H. Fox, K. B. Yap, D. H. McConville, R. O’Dell,
B. J. Lichtenstein and R. R. Schrock, J. Organomet. Chem., 1993, 459,
185.
4 J. B. Arterburn, I. M. Fogarty, K. A. Hall, K. C. Ott and J. L. Bryan,
Angew. Chem., 1996, 35, 2877.
5 O. D. Sloan and P. Thornton, Polyhedron, 1988, 7, 329.
6 J. R. Dilworth, V. C. Gibson, C. Lu, J. R. Miller and C. Redshaw,
J. Chem. Soc., Dalton Trans., 1997, 269.
7 SMART (control) and SAINT (frame integration) software for CCD
diffractometers, Siemens Analytical X-ray Instruments, Madison,
WI, 1994, together with local programs.
Crystal data and other information on the structure determin-
ations are given in Table 7. All measurements were made at 160
K on a Siemens SMART CCD diffractometer with Mo-Kα
radiation (λ = 0.71 073 Å).7 Cell parameters were refined from
observed setting angles of all strong reflections in each com-
plete data set, which consisted of more than a hemisphere of
data measured from several series of narrow-frame exposures
(0.3Њ in ω).7 Analysis of redundant and symmetry-equivalent
reflections indicated no significant intensity decay, and formed
the basis for semiempirical absorption corrections.8
The structures were solved variously by heavy-atom and dir-
ect methods, and were refined on F 2 values for all reflections,8
2
with weighting
w
Ϫ1 = σ2(Fo ) ϩ (aP)2 ϩ bP, where P =
8 G. M. Sheldrick, SHELXTL, version 5, Siemens Analytical X-Ray
Instruments, Madison WI, 1995.
(Fo2 ϩ 2Fc )/3. An isotropic extinction coefficient x was refined,
2
¹
whereby F Јc = Fc/(1 ϩ 0.001xFc λ3/sin 2θ) . Disorder was
resolved for one cation of complex 2, and for the organic
ligands, cation and dme solvent of 6ؒdme, and was successfully
refined with the aid of geometrical and displacement parameter
2
⁴
Received 4th March 1997; Paper 7/01502J
3212
J. Chem. Soc., Dalton Trans., 1997, Pages 3207–3212