Vanadium complexes of the N(CH2CH2S)33- and O(CH2CH2S)22- ligands with coligands relevant to nitrogen fixation processes

Article abstract of DOI:10.1021/ic9909476

Vanadium(III) and vanadium(V) complexes derived from the tris(2-thiolatoethyl)amine ligand [(NS₃)^3-] and the bis(2-thiolatoethyl)ether ligand [(OS₂)^2-] have been synthesized with the aim of investigating the pot

Full text of DOI:10.1021/ic9909476

Inorg. Chem. 2000, 39, 3485-3498
3-
3485
2-
Vanadium Complexes of the N(CH2CH2S)3 and O(CH2CH2S)2 Ligands with Coligands
Relevant to Nitrogen Fixation Processes
Sian C. Davies,† David L. Hughes,† Zofia Janas,‡ Lucjan B. Jerzykiewicz,‡
Raymond L. Richards,† J. Roger Sanders,*,† James E. Silverston,† and Piotr Sobota‡
Nitrogen Fixation Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, U.K., and
Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw, Poland
ReceiVed August 6, 1999
Vanadium(III) and vanadium(V) complexes derived from the tris(2-thiolatoethyl)amine ligand [(NS3)3-] and the
bis(2-thiolatoethyl)ether ligand [(OS2)2-] have been synthesized with the aim of investigating the potential of
these vanadium sites to bind dinitrogen and activate its reduction. Evidence is presented for the transient existence
of {V(NS3)(N2)V(NS3)}, and a series of mononuclear complexes containing hydrazine, hydrazide, imide, ammine,
organic cyanide, and isocyanide ligands has been prepared and the chemistry of these complexes investigated.
[V(NS3)O] (1) reacts with an excess of N2H4 to give, probably via the intermediates {V(NS3)(NNH2)} (2a) and
{V(NS3)(N2)V(NS3)} (3), the VIII adduct [V(NS3)(N2H4)] (4). If 1 is treated with 0.5 mol of N2H4, 0.5 mol of N2
is evolved and green, insoluble [{V(NS3)}n] (5) results. Compound 4 is converted by disproportionation to [V(NS3)-
(NH3)] (6), but 4 does not act as a catalyst for disproportionation of N2H4 nor does it act as a catalyst for its
reduction by Zn/HOC6H3Pri2-2,6. Compound 1 reacts with NR1 NR2 (R1 ) H or SiMe3; R2 ) Me2, MePh, or
2
2
2
HPh) to give the hydrazide complexes [V(NS3)(NNR2 )] (R2 ) Me2, 2b; R2 ) MePh, 2c; R2 ) HPh, 2d),
2
2
2
2
which are not protonated by anhydrous HBr nor are they reduced by Zn/HOC6H3Pri2-2,6. Compound 2b can also
be prepared by reaction of [V(NNMe2)(dipp)3] (dipp ) OC6H3Pri2-2,6) with NS3H3. N2H4 is displaced quantitatively
from 4 by anions to give the salts [NR3 ][V(NS3)X] (X ) Cl, R3 ) Et, 7a; X ) Cl, R3 ) Ph, 7b; X ) Br, R3 )
4
Et, 7c; X ) N3, R3 ) Bun, 7d; X ) N3, R3 ) Et, 7e; X ) CN, R3 ) Et, 7f). Compound 6 loses NH3 thermally
to give 5, which can also be prepared from [VCl3(THF)3] and NS3H3/LiBun. Displacement of NH3 from 6 by
ligands L gives the adducts [V(NS3)(L)] (L ) MeCN, νCN 2264 cm-1, 8a; L ) ButNC, νNC 2173 cm-1, 8b; L )
C6H11NC, νNC 2173 cm-1, 8c). Reaction of 4 with N3SiMe3 gives [V(NS3)(NSiMe3)] (9), which is converted to
[V(NS3)(NH)] (10) by hydrolysis and to [V(NS3)(NCPh3)] (11) by reaction with ClCPh3. Compound 10 is converted
into 1 by [NMe4]OH and to [V(NS3)NLi(THF)2] (12) by LiNPri in THF. A further range of imido complexes
[V(NS3)(NR4)] (R4 ) C6H4Y-4, where Y ) H (13a), OMe (13b), Me (13c), Cl (13d), Br (13e), NO2 (13f); R4 )
C6H4Y-3, where Y ) OMe (13g); Cl (13h); R4 ) C6H3Y2-3,4, where Y ) Me (13i); Cl (13j); R4 ) C6H11 (13k))
2-
has been prepared by reaction of 1 with R4NCO. The precursor complex [V(OS2)O(dipp)] (14) [OS2
)
O(CH2CH2S)22-] has been prepared from [VO(OPri)3], Hdipp, and OS2H2. It reacts with NH2NMe2 to give [V(OS2)-
(NNMe2)(dipp)] (15) and with N3SiMe3 to give [V(OS2)(NSiMe3)(dipp)] (16). A second oxide precursor, formulated
as [V(OS2)1.5O] (17), has also been obtained, and it reacts with SiMe3NHNMe2 to give [V(OS2)(NNMe2)(OSiMe3)]
(18). The X-ray crystal structures of the complexes 2b, 2c, 4, 6, 7a, 8a, 9, 10, 13d, 14, 15, 16, and 18 have been
determined, and the 51V NMR and other spectroscopic parameters of the complexes are discussed in terms of
electronic effects.
Introduction
(plus other ligands) (MS3 sites), is therefore of great importance
in understanding the mode of action of these enzymes. In
particular, if one or a number of these metals is directly
involved in the reduction of N2 to NH3, the process might
involve intermediate ligand species such as N2Hm and NHn (m
) 0-4; n ) 0-3)5,6 bound at MS3 sites.7
In terms of studies that might relate to the function of
vanadium nitrogenase, while it has been demonstrated that S3-
ligated vanadium in cluster anions such as [Fe3S4X3V(DMF)3]-
The cofactor of molybdenum nitrogenase (FeMoco) is
considered to be the site at which this enzyme converts nitrogen
gas into ammonia.1 FeMoco has been shown by X-ray crystal-
lography to contain an MoFe7S9 cluster with the Mo atom ligated
by one nitrogen, three sulfur, and two oxygen atoms,2 and it is
thought that the vanadium atom in the analogous vanadium
nitrogenase3 is in a similar environment, as is possibly one of
the iron atoms in the third “iron-only” nitrogenase.4 The
chemistry of V, Mo, and Fe centers, which carry three sulfurs
(4) Pau R. N. In Biology and Biochemistry of Nitrogen Fixation; Dilworth,
M. J., Glenn, A. R., Eds.; Elsevier: Oxford, 1991; p 37.
(5) Henderson, R. A.; Leigh, G. J.; Pickett, C. J. AdV. Inorg. Chem.
Radiochem. 1984, 27, 197.
(6) Galindo, A.; Hills, A.; Hughes, D. L.; Hughes, M.; Mason, J.; Richards,
R. L. J. Chem. Soc., Dalton Trans. 1990, 283.
† John Innes Centre.
‡ University of Wroclaw.
(1) Evans, D. J.; Henderson, R. A.; Smith, B. E. In Bioinorganic Catalysis,
2nd ed.; Reedjik, J., Bouwman, E., Eds.; Marcel Decker, Inc.: New
York, 1999; Chapter 7.
(2) Rees, D. C.; Chan, M. K.; Kim, J. AdV. Inorg. Chem. 1993, 40, 89.
(3) Eady, R. R. Chem. ReV. 1996, 96, 3013 and references therein.
(7) Richards, R. L. Coord Chem. ReV. 1996, 154, 83. Hidai, M.; Mizobe,
Y. Chem. ReV. 1995, 95, 1115.
10.1021/ic9909476 CCC: $19.00 © 2000 American Chemical Society
Published on Web 07/21/2000

3486 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
Table 1. Selected Bond Dimensions in the Vanadium Complexes [VIII(NS3)Z1], [VV(NS3)Z2], and [VV(OS2)Z3]a
mean N-V-S
Z
V-N(NS3) mean V-S in NS3 ligand
Z, V-Z
other dimensions in the Z ligand
[VIII(NS3)Z1]
NCMe, 8a
NH3, 6
2.147(2)
2.155(8)
2.287(2)
2.290(6)
86.3(4)
86.1(2)
N, 2.097(2) N(2)-C(7) 1.126(3); C(7)-C(8) 1.451(4);
V-N(2)-C(7) 170.9(2);N(2)-C(7)-C(8) 177.2(3)
N, 2.154(7) N(5)-H(5a) 0.92(3); N(5)-H(5b) 0.91(4);
N(5)-H(5c) 0.92(4); N(5)‚‚‚S(1′) 3.415(9);
N(5)‚‚‚S(3′′) 3.670(9); N(5)‚‚‚S(2′′) 3.499(9)
NH2NH2, 4, mol. 1 2.180(9)
2.306(4)
2.296(7)
2.304(1)
85.2(6)
86.2(2)
84.7(1)
N, 2.135(10) N(15)-N(16) 1.48(2); V-N(15)-N(16) 111.7(8)
N, 2.157(10) N(25)-N(26) 1.46(2); V-N(25)-N(26) 115.3(7)
Cl, 2.369(1)
mol. 2
2.154(9)
2.183(3)
Cl,b 7a
[VV(NS3)Z2]
NNMe2, 2b
2.214(3)
2.263(3)
84.4(3)
N, 1.681(3) N(2)-N(3) 1.305(5); V-N(2)-N(3) 173.9(4);
N(3)-C(7) 1.40(2); N(3)-C(8) 1.50(2);
N(2)-N(3)-C(7) 118.9(11); N(2)-N(3)-C(8) 115.3(12);
C(7)-N(3)-C(8) 118.4(5)
N, 1.682(2) N(2)-N(3) 1.310(3); V-N(2)-N(3) 177.8(2);
N(3)-C(7) 1.459(3); N(3)-C(8)1.400(3);
N(2)-N(3)-C(7) 117.1(2); N(2)-N(3)-C(8) 120.3(2);
C(7)-N(3)-C(8) 122.6(2)
N, 1.670(2) N(5)-C(51) 1.379(3); V-N(5)-C(51) 171.0(2)
N, 1.638(3) N(5)-H(5) 0.80(4); V-N(5)-H(5) 179(3);
H(5)‚‚‚S(1′) 2.62(4); N(5)-H(5)‚‚‚S(1′) 158(4);
N(5)‚‚‚S(1′) 3.367(3)
N, 1.647(6) N(2)-Si 1.766(6); V-N(2)-Si 163.9(5)
N, 1.642(5) N(5)-Si(5) 1.786(5); V-N(5)-Si(5) 163.2(3)
O, 1.578(6)
NNMePh, 2c
2.218(2)
2.265(2)
84.4(3)
NC6H4Cl-4, 13d
NH, 10
2.228(2)
2.234(2)
2.251(3)
2.253(1)
84.4(4)
83.8(3)
NSiMe3, 9, str 1
str 2
2.271(6)
2.263(5)
2.291(6)
2.255(4)
2.255(2)
2.246(2)
83.6(4)
83.7(5)
83.2(2)
O, 1 16
[VV(OS2)Z3(dipp)]
mean O-V-S
in (OS2) ligand
other dimensions in the
Z3
V-O(OS2)
mean V-S
Z, V-Z
V-Oeq, O(2)
V-O(2)-C(11)
Z ligand
NNMe2,c 18
2.148(2)
2.165(2)
2.210(4)
2.225(2)
2.269(6)
81.8(6)
81.9(5)
81.4(7)
80.2(3)
N, 1.678(2)
1.798(2)
c
N(1)-N(2) 1.300(3);
V-N(1)-N(2) 164.6(2)
N(1)-N(2) 1.296(4);
V-N(1)-N(2) 174.1(3)
N-Si 1.747(5);
NNMe2, 15
NSiMe3, 16
O, 14
2.274(1)
2.259(3)
2.253(1)
N, 1.675(3)
N, 1.635(5)
O, 1.573(2)
1.803(2)
1.808(3)
1.785(2)
134.1(2)
129.8(3)
134.1(2)
V-N-Si 174.1(3)
a Bond lengths are in Ångstroms, angles in degrees. Atom labels may be found in the figures. Estimated standard deviations or standard deviations
of mean values, are in parentheses. b In the anion [V(NS3)Cl]-. c Complex 18 is [VV(OS2)(NNMe2)(OSiMe3)]; the V-O(2)-Si angle is 139.3(1)°.
(X ) Cl, Br, or I) binds hydrazine and catalyzes its reduction8
and while hydrazines9 and imides10 have been shown to bind
at mononuclear, thiolate-ligated vanadium, generally very little
chemistry of reduced nitrogen species at vanadium in a sulfur-
donor environment has been reported. To help redress this
at which dinitrogen is reduced to ammonia via an established
series of mononuclear intermediate species, particularly hy-
drazide and imide complexes, e.g., in [MoCl(NNH2)(dppe)2]+
and [MoCl(NH)(dppe)2]+ (dppe ) Ph2PCH2CH2PPh2).14,15
By this means we aimed to gain knowledge of the potential
of these vanadium-sulfur sites to bind dinitrogen and activate
its reduction. The outcome of this vanadium work, some of
which has been reported in a preliminary form,11 is described
below.
3-
deficiency, we decided to use the ligands N(CH2CH2S)3
2-
[NS3]3- and O(CH2CH2S)2 [OS2]2- to generate a range of
complexes of N2Hm, NHn and related ligands at VNS3 and VOS2
sites. We aim to relate the nitrogen chemistry of these sulfur-
ligated sites to that of analogous Mo and Fe sites11 and also to
that of other vanadium sites where dinitrogen is bound, e.g., in
such compounds as [(Pri2N)3V(µ-N2)V(Pri2N)3]12 and
[V(N2)2(dppe)2]-,13 and more generally to that of metallic sites
Results and Discussion
In the following discussion of the compounds that we have
made, selected bond dimensions for all structurally characterized
compounds are in Table 1 and full crystallographic details are
in Tables 2 and 3.
Hydrazine and Hydrazide Complexes of the NS33- Ligand.
Treatment of [VO(NS3)]16 (1) with 4 equiv of anhydrous
hydrazine in acetonitrile removes the oxide ligand to give, via
the intermediates 2a and 3 discussed below, an almost quantita-
tive yield of the complex [V(NS3)(NH2NH2)] (4) as a poorly
soluble yellow powder. Although crystals of 4 for an X-ray study
were obtained, intensity data for 4 proved to be very difficult
(8) Malinak, S. M.; Demadis, K. D.; Coucouvanis, D. J. Am. Chem. Soc.
1995, 117, 3126.
(9) Le Floc’h, C.; Henderson, R. A.; Hitchcock, P. B.; Hughes, D. L.;
Janas, Z.; Richards, R. L.; Sobota, P.; Szafert, S. J. Chem. Soc., Dalton
Trans. 1996, 2755. Henderson, R. A.; Janas, Z.; Richards, R. L.;
Sobota, P. Unpublished results.
(10) Preuss, F.; Noichel, H.; Kaub, J. Z. Naturforsch. 1986, 41b, 1085.
(11) Davies, S. C.; Hughes, D. L.; Janas, Z.; Jerzykiewicz, L.; Richards,
R. L.; Sanders, J. R.; Sobota, P. J. Chem. Soc., Chem. Commun. 1997,
1261. Davies, S. C.; Hughes, D. L.; Richards, R. L.; Sanders, J. R. J.
Chem. Soc., Chem. Commun. 1998, 2699.
(12) Song, J.-I.; Berno, P.; Gambarotta, S. J. Am. Chem. Soc. 1994, 116,
6927.
(13) Rehder, D.; Woitha, C.; Priebsch, W.; Gailus, H. J. Chem. Soc., Chem.
Commun. 1992, 364.
(14) Chatt, J.; Heath, G. A.; Richards, R. L. J. Chem. Soc., Dalton Trans.
1974, 2074.
(15) Chatt, J.; Dilworth, J. R. J. Indian Chem. Soc. 1977, 54, 13.

Table 2. Crystallographic Data for the Complexes [V(NS3)Z]a
compound
2b
2c
4
6
7a
8a
9, str 1
NSiMe3
C9H21N2S3SiV
332.5
9, str 2
NSiMe3
C9H21N2S3SiV
332.5
10
13d
Z
NNMe2
NNMePh
C13H20N3S3V
365.4
NH2NH2
C6H16N3S3V
277.3
NH3
Cl
NCMe
NH
NC6H4Cl-4
C12H16ClN2S3V
370.8
elemental formula
mol wt
C8H18N3S3V
303.4
C6H15N2S3V
262.3
C8H20N,C6H12ClNS3V C8H15N2S3V
C6H13N2S3V
260.3
411.0
286.3
crystal system
space group (no.)
a (Å)
b (Å)
c (Å)
monoclinic
P21 (4)
7.494(1)
11.649(2)
7.584(1)
monoclinic
P21/c (14)
12.713(4)
8.570(3)
monoclinic
P21/n (≈14)b
8.1566(8)
13.584(2)
21.264(17)
orthorhombic
P212121 (19)
8.0612(6)
16.6065(13)
8.5004(12)
orthorhombic
Pbcm (57)
8.773(2)
14.345(4)
15.934(3)
orthorhombic
Pbca (61)
11.787(2)
12.090(3)
17.576(4)
monoclinic
P21/c (14)
11.141(2)
12.035(2)
12.260(3)
monoclinic
P21/c (14)
11.1558(12)
12.040(11)
12.2720(15)
triclinic
P-1 (2)
monoclinic
P21/a (≈14)
13.5753(11)
16.300(2)
7.4103(7)
7.6619(9)
10.5983(13)
86.359(9)
74.676(9)
65.116(9)
525.7(1)
2
1.65
268
14.9
brown-red
triangular
plates
15.225(3)
7.4990(7)
R (deg)
â (deg)
92.03(1)
101.68(3)
100.32(4)
109.55(3)
109.545(9)
102.258(7)
γ (deg)
V (Å3)
661.5(2)
2
1.523
316
12.0
red, rectangular
prisms
1624.4(8)
4
1.494
760
2318(2)
8
1.589
1152
13.6
1137.9(2)
4
1.531
544
2005.3(8)
4
1.361
872
9.4
red blocks
2504.7(9)
8
1.519
1184
12.6
red cubes
1549.1(5)
4
1.426
696
11.0
1553.4(3)
4
1.42
696
11.0
1621.6(3)
4
1.519
760
11.5
deep-red blocks
no. formula units/cell, Z
F (g cm-3
F(000)
)
µ(Mo KR) (cm-1
)
9.9
13.3
crystal color, shape
dark-red cubes pale olive-green
yellow,
translucent
plates
orange square
prisms
orange square
prisms
square prisms
crystal size (mm)
crystal mounting
0.5 × 0.3 ×
0.2
in a glass
capillary
under N2
0.4 × 0.3 ×
0.1
0.19 × 0.29 ×
0.36
0.41 × 0.08 × 0.7 × 0.5 ×
0.05 0.4
on a glass fiber in a glass
capillary,
under N2
0.4 × 0.4 ×
0.35 × 0.3 ×
0.40 × 0.10 ×
0.52 × 0.24 ×
0.31 × 0.21 ×
0.4
0.2
0 07
0.01
0.45
in a glass
capillary
under N2
8.5-13
25
0/15, 0/10,
-18/17
0
on a glass fiber,
sealed with
epoxy resin
10-11
in a glass capillary in a glass capillary on a glass fiber, on a glass fiber, on a glass fiber
under N2
under N2
sealed with
epoxy resin
10-11
20
-10/10, 0/11,
0/11
0
sealed with
epoxy resin
8-11
25
-8/8, -9/9,
0/12
4.7
θ for centered reflections (deg) 8.5-13
10-11
25
8-13
25
7.5-14
25.1
0/14, 0/14,
-20/20
0
as for sphere
3715
7-14
25
0/13, 0/14,
-14/13
15
not applied
1522
10-11
25
θ
max for data collection (deg)
h, k, l range
25
0/8, 0/13,
25
-9/9, -1/16,
-1/9, -1/19,
-1/10
1.0
0/10, 0/17,
-16/16, -1/19,
-9/9
-1/25
0/18
-1/8
cryst degradation (% overall)
transm coeff
total no. reflns measd
(not including absences)
BAYES correction applied
0
9.7
6.5
3.3
not applied
1749
not applied
2461
0.96-1.0
4382
0.81-0.81
1631
not applied
2057
0.96-1.0
1646
0.98-0.99
1952
0.87-0.99
3065
no
no
yes
yes
yes
no
no
yes
yes
yes
R
int for equivalents
0.010
1218
1118
direct methods
0.021
2398
2186
0.047
4028
2368
0.032
1175
729
automated
Patterson
0.085, 0.093
-
0.112
1964
1795
direct methods
0.030
1453
1372
direct methods
0.040
1452
832
automated
Patterson
0.102, 0.084
1452 (all data)
0.019
1841
1451
automated
Patterson
0.044, 0.083
1841 (all data)
0.010
2838
2375
direct methods
total no. of unique reflections
no. obsd reflections (I > 2σI)
structure determination
1846
1357
direct methods
direct methods direct methods
final R1, wR2
no. reflections used
0.031, 0.087
1118
0.039, 0.092
2398 (all data) 2368
0.074, 0.237
0.053, 0.118
0.037, 0.086
1964 (all data)
0.055, 0.145
1453 (all data)
0.035, 0.075
2838 (all data)
1170 (all but 5) 1846 (all data)
(with I > 2σI)
154
(0.031)
(with I > 2σI)
376
no. parameters refined
R1 for the obsd reflns
goodness-of-fit, S (on F2)
reflns weighted, w
212
169
182
128
0.031
1.12
145
0.048
1.15
166
0.040
189
0.031
1.05
185
0.028
1.08
0.034
1.10
(0.074)
0.85
0.049
1.06
0.035
1.11
1.20
1.04
{σ2(Fo2) +
(0.046P)2 +
0.56P}-1
{σ2(Fo2) +
{σ2(Fo2) +
σ-2(Fo
)
{σ2(Fo2) +
{σ2(Fo2) +
(0.048P)2 +
1.37P}-1
{σ2(Fo2) +
(0.088P)2 +
3.80P}-1
{σ2(Fo2) +
{σ2(Fo2) +
(0.038P)2 +
0.11P}-1
{σ-2(Fo2) +
(0.013P)2 +
0.71P}-1
2
(0.062P)2 +
(0.1P)2}-1
(0.073P)2 +
(0.011P)2}-1
0.48P}-1
0.56P}-1
final difference map
highest peaks (e Å-3
location
)
0.36
0.48
0.55
0.35
0.32
in anion, near Cl
0.50
C3 atom
0.60
S1 atom
0.37
0.35
0.23
in the thiolate ligand. V atom
close to V centers near ammine
close to a S atom close to a S atom close to S or
N atom
Cl atoms
a λ(Mo KR) for all analyses is 0.710 69 Å. b Composite cell of a twinned crystal.

3488 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
Table 3. Crystallographic Data for the Complexes [V(OS2)Z(dipp)]a
compound
14
15
16
18
b
Z
O
NNMe2
NSiMe3
NNMe2
elemental formula
mol wt
crystal system
space group (no.)
a (Å)
b (Å)
c (Å)
C16H25O3S2V
380.4
monoclinic
P21/n (≈14)
10.569(2)
14.996(3)
11.896(3)
C18H31N2O2S2V
422.5
monoclinic
C2/c (15)
19.151(5)
7.606(4)
C19H34NO2S2SiV
451.6
triclinic
C9H23N2O2S2SiV
334.4
monoclinic
P21/c (14)
15.223(5)
12.207(4)
9.091(4)
P-1 (2)
9.646(2)
10.103(2)
15.001(3)
91.06(3)
102.12(3)
118.16(3)
1248.4(4)
2
31.258(9)
R (deg)
â (deg)
92.22(3)
100.26(5)
93.53(4)
γ (deg)
V (Å3)
1884.0(7)
4
1.341
800
4480(3)
8
1.253
1792
1686.1(11)
4
1.317
704
no. formula units/cell, Z
F (g cm-3
F(000)
)
1.201
480
6.2
µ(Mo KR) (cm-1
)
7.6
6.4
9.0
crystal color, shape
crystal size (mm.)
crystal mounting
red-orange cubes
0.6 × 0.4 × 0.2
in a glass capillary
under N2
7.5-13
25
0/12, 0/17, -14/14
0
not applied
2881
red cubes
0.5 × 0.3 × 0.3
in a glass capillary
under N2
7.5-14
violet-red blocks
0.9 × 0.5 × 0.3
in a glass capillary
under N2
8-15
orange prisms
0.4 × 0.3 × 0.3
in a glass capillary
under N2
7.5-15
25
-18/18, -14/0, 0/10
0
not applied
2434
θ for centered reflns (deg)
θ
max for data collection (deg)
h, k, l range
30
25
0/22, 0/10, -43/42
0
not applied
3652
-9/0, -10/10, -17/17
21.3
not applied
2746
cryst degradation (% overall)
transm coeff
total no. reflns measd
(not including absences)
BAYES correction applied
no
no
no
no
R
int for equivalents
0.007
2722
2388
direct methods
0.043, 0.098
2722 (all data)
199
0.073
3559
3047
direct methods
0.058, 0.150
3559 (all data)
232
0.021
2541
2236
direct methods
0.060, 0.172
2541 (all data)
242
0.013
2335
2053
direct methods
0.039, 0.088
2335 (all data)
159
total no. unique reflns
no. obsd reflns (I > 2σI)
structure determination
final R1, wR2
no. reflns used
no. parameters refined
R1 for the obsd reflns
goodness-of-fit, S (on F2)
reflns weighted, w
0.034
0.046
0.052
0.030
1.08
1.07
1.12
1.10
{σ2(Fo ) + (0.046P)2 +
{σ2(Fo ) + (0.098P)2 +
{σ2(Fo ) + (0.115P)2 +
{σ2(Fo ) + (0.047P)2 +
2
2
2
2
1.16P}-1
5.84P}-1
1.18P}-1
0.75P}-1
final difference map
highest peaks (e Å-3
location
)
0.47
S2 atom
0.73
C1 atom
0.62
V atom
0.42
N atom
a λ(Mo KR) for all analyses is 0.710 69 Å. b Complex 18 is [V(OS2)(NNMe2)(OSiMe3)].
to measure because all the crystals that we examined were
twinned. Nevertheless, the solution of the structure showed
clearly defined binding of the hydrazine molecule to vanadium
(see Experimental Section).
Each twin (in the composite twinned cell) has two indepen-
dent molecules. We shall describe only the structure of the major
twin; the description of the minor twin is, of course, exactly
the same, but the results are much less precise. The two
independent molecules are virtually identical (Figure 1) with
the same geometries and same dimensions. The V(NS3) moiety
is very similar to that found in the series of more accurately
determined structures described below, with dimensions collated
in Table 1. The hydrazine ligand in each molecule is end-on to
the metal and bent at the ligating nitrogen with V-N-N angles
of 111.7(8) and 115.3(7)°. These angles are in the range of those
seen in related hydrazine complexes of vanadium(III), e.g.,
121.05(5) and 122.7(4)° in [V(OC6H3Pri2-2,6)3(NH2NMe2)2].9
The V-N and N-N distances, mean values of 2.146(11) and
1.469(11) Å, respectively, are both of single bonds.9 Hydrogen
Figure 1. View of a molecule of [V(NS3)(NH2NH2)], 4. In the
composite cell of the twinned crystal examined, there were two virtually
identical, independent molecules (one shown here, with its atom
numbering scheme) of the major twin plus two from the minor twin.
atoms were not located in the hydrazine ligands, but their
positions might be inferred from hydrogen bonding contacts.
The molecules are linked in paired chains parallel to the a axis
in the crystal by N-H‚‚‚N hydrogen bonds, with additional
N-H‚‚‚S bonds within the chains. Contacts between chains are
at normal van der Waals distances. The physical properties of
4 are presented in Experimental Section.

Vanadium Complexes
Inorganic Chemistry, Vol. 39, No. 16, 2000 3489
Scheme 1
The formation of 4 might involve an intermediate dinitrogen
complex {V(NS3)(N2)V(NS3)} (3) formed via a hydrazide
intermediate {V(NS3)(NNH2)} (2a) as shown in Scheme 1.
Although the evidence for this reaction sequence is mainly
circumstantial, we feel that it is a reasonable proposal for the
following reasons. First, the overall stoichiometry of steps 1a
f 1b f 1c has been established quantitatively (see Experi-
mental Section). Second, when the reaction is carried out with
only one hydrazine per two vanadiums (Scheme 1; 1a f 1b f
1d), an intermediate is observed that rapidly evolves 1 mol of
N2 to give 2 mol of {V(NS3)} (5). We have not been able to
isolate this intermediate (3) in a characterizable form even at
low temperature, but its formulation as {V(NS3)(N2)V(NS3)}
appears reasonable in view of the products quantitatively derived
from it and the fact that stable, linear vanadium(III) dinitrogen-
bridged complexes are well-known, although with coligands
other than sulfur.12,17 The proposal of the hydrazide intermediate
precursor to this bridged dinitrogen intermediate, {V(NS3)-
(NNH2)} (2a), (step 1a in Scheme 1), follows because treatment
Figure 2. Molecule of the hydrazido(2-) complex [V(NS3)(NNMePh)]
(2c), showing the alternative conformations of the NS3 ligand.
This geometry is essentially maintained throughout the range
of complexes of the [NS3]3- ligand whose structures we present
in this paper, and this allows us to compare the trans influence
of ligands and other features at the V(NS3) site as are discussed
below.
The N-N distance of the hydrazide ligands [1.305(5) Å in
2b and 1.310(3) Å in 2c] are in the range generally found5,14,18,19
in hydrazide complexes of the early transition metals and in
the only other structurally characterized hydrazide complexes
of vanadium, [V(C5H5)2{NN(SiMe3)2}] [1.369(9) Å],20 the anion
[VCl2(NH2NMePh)2(NNMePh)]- [1.295(17) Å],21 [(C9H18N2)2-
(OSiMe3)2V(µ-O)V(O)(OSiMe3)2] [1.285(3) and 1.245(4) Å],22
and [V(OC6H3Pri2-2,6)3(NNMe2)] [1.311(4) Å].18 However,
while there is no doubt about the nature of the NNMe2 ligand
in 2b, it is unusual in that the N-C distances appear to be
unequal [1.401(15) and 1.502(15) Å] and that the Nâ atom lies
some 0.21 Å out of the plane formed by the surrounding NC2
atoms. This appears to be an artifact of the structural determi-
nation, since the hydrazide ligand in 2c is essentially planar, as
is usually observed for these delocalized ligands.18-22
Hydrazide complexes are well-established intermediates in
the high-yield stoichiometric conversion to ammonia of dini-
trogen bound at Mo and W with phosphine coligands.5,6 Such
intermediates might also be involved in related reactions at
analogous vanadium13 and iron23 sites and at a molybenum
macrocyclic thioether site,24 but yields of ammonia are low and
the reaction pathways have not been studied in any detail. With
this in mind, we attempted to protonate the hydrazide ligands
in compounds 2b and 2c with halogen acid and to reduce them
with Zn/HOC6H3Pri2-2,6 (Hdipp), but neither protonation nor
reduction was observed.
of 1 with substituted hydrazines, NR1 NR22 (R1 ) H or SiMe3;
2
R2 ) Me2, MePh, or HPh), gives the diamagnetic hydrazide
2
complexes [V(NS3)(NNR2 )] (2b-d), (step 1e of Scheme 1),
2
which can be regarded as stabilized analogues of 2a that cannot
undergo step 1b in Scheme 1. Compound 2b has also been
prepared by reaction of [V(OC6H3Pri2-2,6)3(NNMe2)]18 with
NS3H3 [reaction 1]. NMR and other physical properties of these
[V(OC6H3Pri2-2,6)3(NNMe2)] + NS3H3 hexanes8
[V(NS3)(NNMe2)] (2b) + 3HOC6H3Pri2-2,6 (1)
complexes are listed in Experimental Section; 51V NMR data
are also discussed separately in the appropriate section below.
The structure of [V(NS3)(NNMe2)] (2b) is very similar to
that shown in Figure 1, and that of [V(NS3)(NNMePh)] (2c) is
shown in Figure 2. Selected bond distances and angles are in
Table 1. As far as we are aware, these are the first hydrazide
complexes of vanadium with sulfur-donor coligands to be
structurally characterized. In both compounds the geometry
about the vanadium is trigonal bipyramidal with the S atoms in
the equatorial positions and the N-V-N system almost linear.
(16) Nanda, K. K.; Sinn, E.; Addison, A. W. Inorg Chem. 1996, 35, 1.
(17) (a) Edema, J. J. H.; Meetsma, A.; Gambarotta, S. J. Am. Chem. Soc.
1989, 111, 6878. (b) Berno, P.; Hao, S.; Minhas, R.; Gambarotta, S.
J. Am. Chem. Soc. 1994, 116, 7417. (c) Buijink, J.-K. F.; Meetsma,
A.; Teuben, J. H. Organometallics 1993, 12, 2004. (d) Ferguson, R.;
Solari, E.; Floriani, C.; Osella, D.; Ravera, M.; Re, N.; Chiesa-Villa,
A.; Rizzoli, C. J. Am. Chem. Soc. 1998, 119, 10104.
(19) Dilworth, J. R.; Gibson, V. C.; Lu, C.; Miller, J. R.; Redshaw, C.;
Zheng, Y. J. Chem. Soc., Dalton Trans. 1997, 269 and references
therein.
(20) Veith, M. Angew. Chem., Int. Ed. Engl. 1976, 15, 387.
(21) Bultitude, J.; Larkworthy, L. F.; Povey, D. C.; Smith, G. W.; Dilworth,
J. R.; Leigh, G. J. J. Chem. Soc., Chem. Commun. 1986, 1748.
(22) Danopoulos, A. A.; Hay-Motherwell, R. S.; Sweet, T. K. N.;
Hursthouse, M. B. Polyhedron 1997, 16, 1081 and references therein.
(23) Hall, D. A.; Leigh, G. J. J. Chem. Soc., Dalton Trans. 1996, 3539.
(18) Henderson, R. A.; Janas, Z.; Jerzykiewicz, L.; Richards, R. L.; Sobota,
P. Inorg, Chim. Acta 1998, 285, 178.

3490 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
Figure 3. Proposed hydrogen bonds in crystals of [V(NS3)(NH3)] (6).
Reactions of [V(NS3)(NH2NH2)] (4) and [V(NS3)(NH3)] (6).
The reactivity of 4 has been investigated primarily with regard
to the disproportionation and reduction of the hydrazine ligand,
since reduction of hydrazine is catalyzed, albeit rather slowly,
at VS3 cluster sites8 and both reduction and disproportionation
of hydrazine are catalyzed at cluster25 and mononuclear26 MoS3
sites.
When 4 is heated in suspension in tetrahydrofuran, a
disproportionation reaction takes place and a yellow solution
results from which [V(NS3)(NH3)] (6) crystallizes on cooling:
Compound 6 is itself thermally unstable and slowly releases
NH3 to give the poorly soluble compound formulated as [{V-
(NS3)}n] (5),
6
MeOH8 [{V(NS3)}n] (5) + NH3
(3)
reflux
which was also formed by a different route as shown in step 1d
of Scheme 1. Presumably, 5 is at least dimeric because of
bridging sulfur ligation, and it is essentially a pit into which
most vanadium(III)-NS3 species tend to fall in the absence of
ligands that are able to bind the vanadium sufficiently strongly
to prevent formation of sulfur bridges (see below). Direct
synthesis of 5 can be achieved by treatment of 1 with AlEt2-
(OEt),
70 °C
3[V(NS3)(NH2NH2)] (4)
8
THF
3[V(NS3)(NH3)] (6) + N2 + NH3 (2)
MeCN
The stoichiometry of reaction 2 has been established by
quantitative measurement of all products (see Experimental
Section).
1
8 [{V(NS3)}n] (5)
(4)
AlEt2(OEt)
or by reaction of [VCl3(THF)3] with NS3H3 and LiBun,
However, despite this stoichiometric disproportionation reac-
tion, complex 4 does not act as a catalyst for the dispropor-
tionation of hydrazine nor does it act as a catalyst for its
reduction by Zn/Hdipp (see Experimental Section). This con-
trasts to some extent with the behavior of the VS3 clusters
[Fe3S4X3V(DMF)3]- (X ) Cl, Br, or I), which catalyze
reduction of hydrazine,8 although not its disproportionation.
The X-ray structure of 6 shows a disordered NS3 ligand (as
in Figure 2) and an apically ligated NH3 group. As expected,
the V-NH3 distance in 6 [2.154(7) Å] is much longer than the
[VCl3(THF)3] + NS3H3 THF 8 [{V(NS3)}n] (5) + 3LiCl (5)
LiBun
Once formed, compound 5 does not react with ligands such as
NH3 and MeCN, but adducts of the V(NS3) unit can be
synthesized readily by alternative routes from compounds 4 and
6. Thus, compound 4 reacts with anions to give the salts [NR3 ]-
4
[V(NS3)X] (X ) Cl, R3 ) Et, 7a; X ) Cl, R3 ) Ph, 7b; X )
Br, R3 ) Et, 7c; X ) N3, R3 ) Bun, 7d; X ) N3, R3 ) Et, 7e;
X ) CN, R3 ) Et, 7f):
V-NNR2 distances in 2b [1.681(3) Å] and 2c [1.682(2) Å],
2
and the V-NS3 distance, 2.155(8) Å in 6, is correspondingly
shorter than the V-NS3 distance in 2b [2.214(3)]Å and 2c
[2.218(2)]Å], which approach that in [VO(NS3)] [1; 2.291(6)
Å].16 Individual molecules of 6 are held in chains by hydrogen
bonds between the three hydrogen atoms of the ammine ligand
and the S atoms of neighboring molecules as shown in Figure
3.
4 + [NR3 ]X MeCN8 [NR3 ][V(NS3)X] (7a-f) + N2H4 (6)
4
4
The X-ray structure of one example of this series, 7a, was
determined and shows a disordered molecule similar to that
shown in Figure 2, with a chloride ligand in the apical position.
The anion has the usual trigonal bipyramidal geometry with a
V-N distance of 2.183(3) Å and a V-Cl distance of 2.369(1)
Å. Compounds 7a-f can also be obtained by displacement of
NH3 from 6 by anions. It is also to be noted that although use
of 4 and a small excesss of [NEt4]CN in reaction 6 gives 7f in
(24) Yoshida, T.; Adachi, T.; Ueda, T.; Kaminaka, M.; Sasaki, N.; Higuchi,
T.; Aoshima, T.; Mega, I.; Mizobe, Y.; Hidai, M. Angew. Chem., Int.
Ed. Engl. 1989, 28, 1040.
(25) Demadis, K. D.; Coucouvanis, D. Inorg. Chem. 1994, 33, 4195.

Vanadium Complexes
Inorganic Chemistry, Vol. 39, No. 16, 2000 3491
high yield, if a ratio of 4 to [NEt4]CN of 2:1 is used in the
reaction, the dinuclear compound [{V(NS3)}2(µ-CN)] results,11
which will be described elsewhere.
Displacement of NH3 from 6 by L,
[V(NS3)(NH3)] (6) + L f [V(NS3)L] (8) + NH3 (7)
(L ) MeCN, 8a; L ) ButNC, 8b; L ) C6H11NC, 8c) gives the
adducts [V(NS3)(L)] [L ) MeCN, νCN 2264 cm-1 (2254 cm-1
for free ligand), 8a; L ) ButNC, νNC 2173 cm-1 (2136 cm-1
for free ligand), 8b; L ) C6H11NC, νNC 2173 cm-1 (2136 cm-1
for free ligand), 8c], but no such displacement occurs for N2,
H2, C2H2, or CO. It is worth noting at this point that a similar
pattern of reactivity has been observed by Schrock and co-
3-
workers for the related vanadium sites V(NN3) [NN3
)
{N(CH2CH2NR)3}3- (R ) C6F5, SiMe3, etc.)].27 Unlike the
V(NS3) site in compound 5, the V(NN3) sites can exist as
monomers for steric reasons and because nitrogen is not such
a potent bridging atom as sulfur. Nevertheless, the V(NN3) sites
resemble the V(NS3) site in that although they bind anions,
MeCN, and ButNC, they do not bind CO, N2, or H2.27 Thus,
although ligands designed to give steric constraint can limit
competing interactions with the vanadium, clearly it is the
electronic condition of the metal site that is of prime importance
in determining whether CO, N2, or H2 interacts with it.
The structure of trigonal-bipyramidal compound 8a shows
an ordered molecule similar to that in Figure 1. It has an
essentially linear N-V-N-C-C group, and the V-N distances
of 2.147(2) Å (to the NS3 ligand) and 2.097(2) Å (to the NCMe
ligand) are the shortest of their type in Table 1.
Figure 4. Hydrogen-bonded dimer units of [V(NS3)(NH)] (10).
) C6H11 (13k)) have also been prepared by the well-known
route28
[V(NS3)O] (1) + R4NCO f
[V(NS3)(NR4)] (13a-k) + CO2 (13)
The conditions of reaction 13 generally involve high temper-
ature, with the isocyanate itself or 2-methoxyethanol as solvent,
which demonstrates the robust nature of these imide complexes.
The X-ray structures of compounds 9, 10, and 13d have been
determined and take the same form as complex 4 (Figure 1).
They all have the expected trigonal bipyramidal geometry with
variations in the fifth apical ligand site. The V-imide distance
of 9, mean value of 1.645(3) Å, is somewhat shorter than that
of [V(C5H5)2(NSiMe3)]29 (1.665 Å) but longer than in [VCl3-
(NSiMe3)]30 (1.59 Å) and in the usual range for imide complexes
generally (1.59-1.73 Å), which are regarded as having close
to a triple bond between the metal and the imide nitrogen.27-31
The corresponding distances in 10 and 13d are 1.638(3) Å and
1.670(2) Å, respectively. Compound 10 is a further example of
the relatively rare class of NH complexes; an analogue [V{N-
(CH2CH2NSiMe3)3}(NH)]27 is known that has a V-N distance
[1.638(6) Å] identical to that of 10. In both [V{N(CH2CH2-
NSiMe3)3}(NH)] and 10, the imido hydrogen has been located
and refined, showing, in both cases, that the V-N-H angle is
close to linear [173(6)° and 179(3)°, respectively] and that the
N-H distances are essentially identical [0.79(7) and 0.80(4)
Å, respectively]. A difference between the structures is due to
sulfur ligation, in that 10 shows a hydrogen bonding interaction
in the solid state between the hydrogen atom of the NH group
and an S atom in a neighboring molecule, thus linking molecules
in pairs about a center of symmetry (Figure 4).
Imide Complexes. Treatment of 4 with SiMe3N3 gives the
diamagnetic imido complex [V(NS3)(NSiMe3)] (9) as shown in
reaction 8. The all-nitrogen-donor analogue [V{N(CH2CH2-
4 + SiMe3N3 MeCN8 [V(NS3)(NSiMe3)] (9) + N2 + N2H4
80 °C
(8)
27
NSiMe3)3}(NSiMe3)] is known.
Complex 9 is a useful precursor to a range of other imide
complexes. Thus, it can be smoothly hydrolyzed to the imide
complex 10 (reaction 9) and reacts with ClCPh3 to give [V(NS3)-
(NCPh3)] (11) [reaction 10]. Complex 10 reacts with [NMe4]-
OH to regenerate [V(NS3)O] (1) [reaction 11] and with LiN(i-
Pr) to give [V(NS3){NLi(THF)2}] (12) [reaction 12].
MeCN/H O8 [V(NS3)(NH)] (10)
(9)
2
9
20 °C
9 + ClCPh3 MeCN8 [V(NS3)(NCPh3)] (11) + SiMe3Cl (10)
reflux
10 [NMe ]OH/MeOH8 [V(NS3)O] (1)
(11)
(12)
4
60 °C
LiNPri
10 THF/20 °C8 [V(NS3){NLi(THF)2}] (12)
General Structural Considerations of NS3 Complexes. The
range of structurally related compounds that we have obtained,
A further range of imido complexes [V(NS3)(NR4)] (R4 )
C6H4Y-4, where Y ) H (13a), OMe (13b), Me (13c), Cl (13d),
Br (13e), NO2 (13f); R4 ) C6H4Y-3, where Y ) OMe (13g),
Cl (13h); R4 ) C6H3Y2-3,4, where Y ) Me (13i), Cl (13j), R4
(28) Devore, D. D.; Lichtenhan, J. D.; Takusagawa, F.; Maatta, E. A. J.
Am. Chem. Soc. 1987, 109, 6878 and references therein.
(29) Wiberg, N.; Haring, H. W.; Schubert, U. Z. Naturforsch. 1980, 356,
599.
(26) Hitchcock, P. B.; Hughes, D. L.; Maguire, M. J.; Marjani, K.; Richards,
R. L. J. Chem. Soc., Dalton Trans. 1997, 4747.
(27) Cummins, C. C.; Schrock, R. R.; Davis, W. M. Inorg. Chem. 1994,
33, 1448.
(30) Schweda, E.; Scherfise, K. D.; Dehnicke, K. Z. Anorg. Allg. Chem.
1985, 528, 117.
(31) Nugent, W. A.; Mayer, J. M. Metal-Ligand Multiple Bonds; Wiley-
Interscience: New York, 1988.

3492 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
[V(NS3)Z], allows comparison of bond parameters within two
series of complexes that have a formally different oxidation state
at vanadium, paramagnetic [VIII(NS3)Z1] (Z1 ) NH2NH2, NH3,
MeCN, and Cl-) and diamagnetic [VV(NS3)Z2] (Z2 ) O,
NNMe2, NNMePh, NSiMe3, NH, and NC6H4Cl-4). For the
series [VIII(NS3)Z1], the V-N distances trans to the group Z1
(d(V-NS3)) span the range 2.147-2.183 Å (Table 1) and give
an order of trans influence (trans bond lengthening) for Z1 of
-
Cl
> NH3 ∼ N2H4 > CH3CN. Similarly, for the series
[VV(NS3)Z2] the distances (d(V-NS3)) span the range 2.214-
2.291 Å and give an order of trans influence for Z2 of O >
NSiMe3 > NH > NC6H4Cl-4 > NNMe2 ∼ NNMePh. Within
the series [V(NS3)NR4] (R4 ) SiMe3, H, or C6H4Cl-4), as the
VdNR4 distances decrease in the order C6H4Cl-4 > SiMe3 >
H, the corresponding distances (d(V-NS3)) increase in the order
C6H4Cl-4 < H < SiMe3 (Table 1). Although the detailed order
is not precisely matched, this trend is as expected for the coupled
N-VdNR4 system.
For [VV(NS3)Z2], as the V-NS3 distances increase, the
average V-S distances correspondingly decrease, as might be
expected for this tripodal ligand (Table 1). This rule does not
appear to be followed for [VIII(NS3)Z1], but in this series the
distances for Z1 ) NH3, N2H4, and CH3CN are all similar and
the anionic charge of the complex when Z1 ) Cl- presumably
lengthens all bonds to the NS3 ligand.
Considering both series, we note that the d(V-NS3) values
for the series [VV(NS3)Z2] are greater than those for [VIII(NS3)-
Z1], despite the smaller ionic radius for VV (ionic radius of VV
) 0.68 Å, ionic radius of VIII ) 0.78 Å); i.e., the Z2 ligands
have the greater trans bond weakening ability. The highest in
trans influence is the oxide ligand followed by imide ligands,
which is not unexpected in view of their good σ-donor power
and π-releasing ability.31 Hydrazides, being good σ-donors and
π-releasing ligands,32 also have a relatively strong trans influ-
ence. Lowest in the series is CH3CN, entirely in keeping with
its overall weakness as a ligand.33
Figure 5. Molecule of [V(OS2)O(dipp)] (14).
[OS2]2- group. The VdO distance [1.573(2) Å] is very close
to that of 1 [1.578(6) Å] and is in the range expected for this
type of compound. Other features of the structure are unexcep-
tional. Compound 14 reacts with NH2NMe2 to give [V(OS2)-
(NNMe2)(dipp)] (15),
14 + NH2NMe2 CH CN8
3
[V(OS2)(NNMe2)(dipp)] (15) + H2O (15)
and with (SiMe3)2NH to give [V(OS2)(NSiMe3)(dipp)] (16),
14 + (SiMe3)2NH CH CN8
3
Complexes of the [O(CH2CH2S)2]2-[OS2]2- Ligand. Be-
cause the ligation of vanadium in nitrogenase appears to involve
oxygen (from homocitrate) as well as sulfur and nitrogen, we
were interested in forming a robust system that would have
oxygen as well as sulfur ligation, and for our initial investigation
we have explored some vanadium chemistry of the [OS2]2-
ligand. Apart from the variation of ligand donor atoms that this
system gives us compared to [NS3]3-, the [OS2]2- ligand confers
a lower coordination number on vanadium so that not only the
nitrogen-donor ligands of choice (hydrazide, imide, etc.) can
be attached to the vanadium but also a variety of other coligands,
such as phenoxide in the examples given in this paper.
Preparations and Structures. As a precursor to the desired
hydrazide and imide complexes, we prepared the oxide complex
[V(OS2)O(dipp)] (14; dipp ) OC6H3Pri2-2,6) from [VO(OPri)3],
Hdipp, and OS2H2 as shown in reaction 14.
[V(OS2)(NSiMe3)(dipp)] (16) + HOSiMe3 (16)
A second oxide precursor, formulated as [V(OS2)1.5O] (17), has
also been obtained,
hexane
[VO(OPri)3] + 1.5OS2H2
8
20 °C
[V(OS2)1.5O] (17) + 3HOPri (17)
and it reacts with SiMe3NHNMe2 to give [V(OS2)(NNMe2)-
(OSiMe3)] (18),
17 + NH(SiMe3)NMe2 CH CN8
3
[V(OS2)(NNMe2)(OSiMe3)] (18) + 0.5H2OS2 (18)
The X-ray structures of 15, 16, and 18 are very similar to
that of 14 (Figure 5). All the V(OS2) compounds have the
expected trigonal bipyramidal structure with two sulfur atoms
of the [OS2]2- ligand and one oxygen atom of the dipp (14, 15,
and 16) or OSiMe3 (18) ligand defining the trigonal plane. The
axial system in 14-16 consists of the O-V-Z3 group in the
series [VV(OS2)Z3(dipp)], where O is the central oxygen of the
[OS2]2- ligand and Z3 ) O, NNMe2, or NSiMe3. Therefore,
we have again a trans influence system, as in the [VV(NS3)Z2]
series above, which gives for V-O(OS2) lengthening the same
trans influence order, O > NSiMe3 > NNMe2, as was seen for
V-N lengthening in [VV(NS3)Z2] (Table 1). Also, in parallel
with trends in the NS3 series, the V-S distances in [VV(OS2)-
hexane
[VO(OPri)3] + Hdipp + OS2H2
8
20 °C
[V(OS2)O(dipp)] (14) + 3HOPri (14)
Red, diamagnetic 14 has ν(VO) at 982 cm-1, and its X-ray
structure is shown in Figure 5. It has essentially trigonal
bipyramidal geometry with the trigonal plane formed by the
oxygen atom of the dipp ligand and the two sulfur atoms of the
(32) Chatt, J.; Fakley, M. E.; Hitchcock, P. B.; Richards, R. L.; Luong-
Thi, N. T. J. Chem. Soc., Dalton Trans. 1982, 345.
(33) Ihmels, K.; Rehder, D. Organometallics 1985, 4, 1340.

Vanadium Complexes
Inorganic Chemistry, Vol. 39, No. 16, 2000 3493
Table 4. 51V NMR and Electronic Spectra of [V(NS3)Z2] and
[V(OS2)Z3(dipp)] in CH2Cl2
(191) > NR(61). Here, we note that the order for both series
does not follow that expected simply from electronegativi-
ties,28,33,34 where the position for Z2 ) O would be expected to
be to the high field of the nitrogen ligands, as is seen for the
series [V{N(CH2CH2NSiMe3)3}Z] (Z ) O or NR).27
no.
Z2 or Z3
51V (ppm)
λ1 (nm)
λ2 (nm)
[V(NS3)Z2]
557
1
2c
2d
O
356
503
Within the imide series [V(NS3)(NR5)] (R5 ) H, SiMe3,
C6H11, CPh3, or R4) the order (ppm) of deshielding with imide
substituent is R4 (321-355) g SiMe3 (349) > CPh3 (234) > H
(210) > C6H11 (194). Thus, there is a greater deshielding for
imides carrying aryl as opposed to alkyl groups. The same trend
was also observed for the four coordinate series [VCl3(NR6)]
(R6 ) alkyl or aryl) and was attributed to a reduction of ∆E
and hence greater deshielding for complexes having aryl
substituents because the HOMO for these compounds is
destabilized as a result of a considerable N-C(aryl) π*
component.28
NNMePh
NNHPh
446
420
2b
13f
9
NNMe2
NC6H4NO2-4
NSiMe3
416
355
349
380
332
329
328
330
329
327
325
332
323
329
331
448
453
444
449
448
452
445
444
450
448
446
454
13j
13b
13d
13e
13h
13c
13i
13g
13a
11
NC6H3Cl2-3,4
NC6H4OMe-4
NC6H4Cl-4
NC6H4Br-4
NC6H4Cl-3
NC6H4Me-4
NC6H3Me2-3,4
NC6H4OMe-3
NPh
337
335
331
331
328
325
325
322
321
234
210
194
There is a relatively very small spread of resonances (321-
355 ppm) within the series [V(NS3)(NR4)] (R4 ) C6H4Y-4,
where Y ) H, OMe, Me, Cl, Br, or NO2). Evidently, variation
of the electronic nature of the aryl substituent has only a minor
effect on the shielding at vanadium (Table 4). Plots of 51V shift
versus Hammett σ constants, Taft σl constants, and Swain’s F
values for the substituents Y show little correlation (data not
shown). This contrasts with the larger effect of substituent on
the 51V resonances of the series [VCl3(NR6)], which span the
range 182-403 ppm.28 Presumably the higher coordination
number of the [V(NS3)(NR4)] series and the buffering effect of
their sulfur ligands contribute to the relatively small range of
resonance for these compounds.
NCPh3
NH
NC6H11
10
13k
[V(OS2)Z3(dipp)]
15
14
16
NNMe2
O
NSiMe3
269
191
61
Z3(dipp)] increase as the axial V-O(OS2) distance decreases.
The equatorial V-O distances in 14-16 and 18, which span
the range 1.785-1.808 Å, are shorter than the corresponding
axial V-O distances, no doubt a consequence of the proximity
of neighboring ligands in the five coordinate complexes and
the anionic nature and stronger binding of the equatorial
phenoxide or alkoxide oxygen compared to the ether-type
oxygen of the axial linkage. The spectroscopic and other
physical properties of complexes 14-18 are given in the
Experimental Section.
All the VV(NS3) compounds we have studied show two
prominent absorptions in the UV/vis region [λ1 (at lower
frequency) and λ2; Table 4], as do members of the series [VCl3-
(NR4)].28 Since these absorptions are related to ∆E, they should
also correlate with the 51V shifts. A correlation with λ1 has been
observed for the [VCl3(NR4)] series; as Cl is replaced by the
more electronegative OAr or OBut, λ1 shifts to higher energy
and the 51V shift moves to higher field.28 In the case of our
[VV(NS3)Z2] complexes, as Z2 is changed from O to NR, the
51V shift moves to higher field and λ1 and λ2 in general move
to higher energy (Table 4). There is little variation in λ1 and λ2
across the imide series.
51V NMR and Electronic Spectra of Complexes. 51V NMR
spectroscopy is a convenient and powerful tool with which to
examine vanadium complexes and, in conjunction with UV/
visible spectroscopy, to probe the electronic manifold of such
compounds. In particular, Rehder has mapped the 51V chemical
shifts corresponding to the vanadium environment33,34 and Maata
has used 51V NMR spectroscopy and UV/visible spectroscopy
to study vanadium oxide and imide compounds.28 In these
studies, the vanadium chemical shift was shown in general to
move to low field (relative to a chosen standard, VOCl3) as the
electronegativity of nonpolarizable ligands at vanadium de-
creased, thus decreasing the mean HOMO-LUMO gap, ∆E,
and increasing the paramagnetic shielding term σ. Ligands that
participate in low-energy ligand-to-metal charge transfer cause
a reduction of ∆E and hence additional deshielding.28,33,34 As
might be expected on this basis, because of the presence of the
highly polarizable sulfur ligands, all the compounds [V(NS3)-
Z2] (Z2 ) O, NR, or NNR2) of this study show shifts downfield
of VOCl3 and the resonances of the NS3 complex series (VNS3L
ligation) are to the low field of the corresponding members of
the OS2 series (VO2S2L ligation) (Table 4). Illustrative of this
general trend are the 51V shifts (ppm) of the analogous pairs of
compounds: [V(NS3)O] 564; [V(OS2)O(OC6H3Pri2-2,6)] 191;
[V(NS3)(NNMe2)] 418; [V(OS2)(OC6H3Pri2-2,6)3(NNMe2)] 269.
Within the [V(NS3)Z2] series, the order of the Z2 ligands in
terms of 51V chemical shift (greatest deshielding) is O (557) >
NNR2 (416-446) > NR (194-355). For the series [V(OS3)(OC6-
H3Pri2-2,6)Z2], the corresponding order is NNR2 (269) > O
In conclusion, although the variation of 51V shift with
electronic transitions and thus ∆E appear to be internally
consistent within our [V(NS3)Z2] series, the relative position of
the oxides [V(NS3)O] and [V(OS2)(OC6H3Pri2-2,6)O] are un-
expectedly low field with respect to complexes of nitrogen
donors, which have lower electronegativity than oxide. In the
absence of detailed theoretical studies, it is not clear what factors
influence ∆E to give rise to this apparent anomaly, but clearly,
it is a consequence of the presence of the NS3 ligand, since the
analogues [V{N(CH2CH2NSiMe3)3}Z]27 follow the expected
order of electronegativities.
Conclusion
The reaction of the VdO unit in 1 and 14, particularly with
hydrazines but also other reagents, has allowed access to a range
of vanadium complexes with various NR (NR ) N2H4, NH3,
NH, etc.) ligands at VNS3 and VOS2 sites. However, although
these vanadium sites are adept at binding nitrogenous species
that could be involved in the latter stages of fixation of N2 at
the vanadium site of vanadium nitrogenase, they are incapable
of binding N2 or other substrates or inhibitors of nitrogenase
3-
such as CO or H2. Similar behavior is seen for their NN3
analogues.27 This might be due to the inability of the VNS3 and
VNN3 sites to match the π-acceptor requirement of a terminal
(34) Rehder, D.; Ihmels, K. Inorg. Chim. Acta 1983, 76, L313.

3494 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
N2 group. An indication of this is that although the d2 VNS3
site is able to bind MeCN in 8a and RNC in 8b and 8c, in
these compounds the NC and CN stretching frequencies are
slightly increased compared to those in the free ligands, whereas
these frequencies generally decrease when these ligands coor-
dinate sites capable of binding CO or N2.35 For example, the d4
compound [Re(NS3)(CNBut)] shows a decrease of ν(NC) of 161
cm-1 relative to that of free CNBut, and [Re(NS3)(CO)] can be
prepared.36
The geometry of the VNS3 site would also accommodate the
bridging mode of N2 binding, and we have presented some
evidence that this does occur weakly, but it might be necessary
to lower the oxidation state of the vanadium to make VNS3, or
a related site, sufficiently electron-releasing to accomplish stable
N2 binding in either the terminal or the bridging mode. We have
observed that ligands other than N2 bind strongly in the bridging
mode. For example, we have obtained the dinuclear compounds
NBu4[(NS3)V(µ-CN)V(NS3)] and NEt4[(NS3)V(µ-N)V(NS3)].11
The properties of these and related complexes will be discussed
in detail elsewhere.
h. The resulting purple crystals were filtered off in air, washed with
acetonitrile-ether and then ether, and dried in vacuo (yield 8.2 g, 31
mmol, 77%). Anal. Calcd for C6H12NOS3V: C, 27.6; H, 4.6; N, 5.4.
Found: C, 27.7; H, 4.5; N, 5.3.
Preparation of [V(NS3)(NNMe2)] (2b). (a) Method A. [V(dipp)3-
(NNMe2)]18 (0.3 g, 0.46 mmol) was dissolved in hexane, and NS3H3
(0.08 cm3, 0.46 mmol) was added. The mixture was stirred overnight
at ambient temperature to give a red solid that was filtered off and
recrystallized from MeCN to give bright-red crystals that were suitable
for crystallographic study. Anal. Calcd for C8H18N3S3V: C, 31.7; H,
1
5.9; N, 13.9. Found: C, 31.4; H, 5.8; N, 13.6. H NMR (CD3CN): ∂
3
3.33 (t, 6H, NCH2CH2S, JH-H 5.5 Hz), 3.43 (s, 6H NCH3), 3.51 (m,
6H, NCH2CH2S). 13C NMR (CD3CN): ∂ 34.61 (NCH2CH2S), 45.16
(NCH3), 57.91 (NCH2CH2S). 51V NMR (CD3CN): ∂ 416 (fwhm )
435 Hz).
(b) Method B. 1 (0.26 g, 1 mmol) and N,N-dimethylhydrazine (5
cm3) were taken to reflux for 3 h and filtered hot. Dark-red crystals
(0.16 g, 53%) of the product crystallized on cooling; they were filtered
off, washed with diethyl ether, and dried in vacuo. They were shown
to be identical to those obtained by method A by spectroscopy and
analysis.
(c) Method C. 1 (0.26 g, 1 mmol) and (SiMe3)NHNMe2 (10 mmol)
were heated under reflux in CH3CN (25 cm3) for 48 h. Cooling to 4
°C gave red crystals (0.2 g, 66%), shown to be identical to those
obtained by method A by spectroscopy and analysis.
Experimental Section
General Information. All operations were carried out under a dry
dinitrogen atmosphere, using standard Schlenk techniques. All the
solvents were distilled under dinitrogen from the appropriate drying
agents prior to use. The compound Me3SiNHNMe2 was prepared by a
literature method.37 All other starting materials were obtained from the
Aldrich Chemical Co. and used without further purification unless stated
otherwise. Infrared spectra were recorded on a Perkin-Elmer 180,
Perkin-Elmer 883, or Shimadzu FTIR-8101M instrument in Nujol mulls
and UV/vis spectra on a Shimadzu UV-2101 PC spectrophotometer.
1H, 13C, 14N, and 51V NMR spectra were measured on a JEOL GSX
270, JEOL JNM-LA400, or Bruker ESP 300E spectrometer (1H and
13C ref SiMe4, 14N ref CH3NO2, 51V ref VOCl3). Standard heteronuclear
multiquantum coherence, heteronuclear multibond correlation, and other
2-D techniques were used as appropriate in the assignment of spectra.
Magnetic moment determinations were either in the solid state, using
Preparation of [V(NS3)(NNMePh)] (2c). The preparation of 2c was
as for 2b (method C), but using (SiMe3)NHNMePh, and gave red
crystals suitable for X-ray analysis (65%). Anal. Calcd for
C13H20N3S3V: C, 42.8; H,5.5; N, 11.5. Found: C, 41.8; H, 5.7; N,
11.8. H NMR (CD3CN): ∂ 3.36 (t, 6H, NCH2CH2S, JH-H 5.5 Hz),
3.63 (m, 6H, NCH2CH2S), 4.06 (s, 6H, NCH3), 7.03-7.61 (m, 5H,
Ph). 13C NMR (CD2Cl2): ∂ 33.95 (NCH2CH2S), 39.2 (NCH3), 57.11
(NCH2CH2S), 113.3, 123.0, 129.1 (NC6H5). 51V NMR (CD3CN): ∂
446 (fwhm ) 606 Hz).
1
3
Preparation of [V(NS3)(NNHPh)] (2d). Phenylhydrazine (8 cm3,
excess) was added to 1 (1.31 g, 5 mmol). The mixture was heated in
vacuo to 150 °C for 10 min, whereupon the purple color became orange-
red. It was cooled and filtered, leaving a very small residue; diethyl
ether (40 cm3) was added as a layer to the filtrate. Dark-red crystals,
suitable for X-ray studies, grew overnight and were filtered off, washed
with diethyl ether, and dried in vacuo (1.55 g, 4.4 mmol, 88%). Anal.
Calcd for C12H18N3S3V: C, 41.0; H, 5.1; N, 12.0. Found: C, 41.5; H,
5.3; N, 12.2. 1H NMR (CD3CN): ∂ 3.35 (t, 6H, NCH2CH2S, 3JH-H 5.4
Hz), 3.61 (m, 6H, NCH2CH2S). 13C NMR (CD3CN): ∂ 34.71
(NCH2CH2S), 57.96 (NCH2CH2S) 112.3, 124.0, 131.1 (NC6H5). 51V
NMR (CD2Cl2): ∂ 420 (fwhm ) 730 Hz). IR (Nujol mull): 3066 cm-1
(m, νNH).
Preparation of [V(NS3)(NH2NH2)] (4). (a) Method A. Anhydrous
hydrazine (6.4 g, 200 mmol) was dissolved in acetonitrile (∼100 cm3).
The solution was decanted from a small residue, then added to a
suspension of 1 (12.3 g, 47 mmol) in acetonitrile (∼100 cm3). The
mixture was stirred at about 50 °C. The color of the suspension changed
from red to green to yellow over about 1 h, then the mixture was cooled
at -20 °C, and the resulting solid was filtered off, washed with
acetonitrile and ether, and dried in vacuo (yield 12.7 g, 46 mmol, 98%).
(b) Method B. Anhydrous hydrazine (0.32 g, 10 mmol) in MeCN
(100 cm3) was added to Et4N[V(NS3)Cl] (8a; 0.21 g, 0.5 mmol) in
MeCN (100 cm3). The solution turned yellow, and crystals suitable
for X-ray studies grew for over a week. Anal. Calcd for C6H16N3S3V:
C, 26.0; H, 5.8; N,15.2. Found: C, 25.6; H, 5.7; N, 15.7. µeff ) 2.82µB.
IR (Nujol mull): 3337, 3248, 3183, 3099 cm-1 (m, νNH).
1
a Johnson-Matthey Gouy balance, or in solution by H NMR using
the Evans method.38 Microanalyses were by Mr. A Saunders of the
University of East Anglia, U.K. or at the University of Wroclaw, Poland.
Preparation of N(CH2CH2SH)3[NS3H3]. A modification of the
literature method was used. Batches of tris(chloroethyl)amine hydro-
chloride39 (CAUTION: VESICANT) were made from 60 g batches of
triethanolamine and converted the same day to tris[2-(S-isothiaureido)-
ethyl]amine tetrahydrochloride.40 This work was carried out in enclosed
Schlenk apparatus while wearing heaVy duty gloVes and a face mask.
The tetrahydrochloride was treated in 0.05 or 0.1 mol batches with
sodium hydroxide,41 giving tris(mercaptoethyl)amine NS3H3. The crude
product was not purified by distillation or by conversion to its
hydrochloride, but rather it was dissolved in diethyl ether and filtered
to remove a white solid, and the ether was removed from the filtrate in
vacuo. The overall yield of NS3H3 from triethanolamine was 30-40%.
Preparation of [V(NS3)O] (1). Following Nanda et al.,16 NS3H3 (9
g, ∼45 mmol) was added to diethyl ether (45 cm3) at 20 °C and the
mixture stirred quickly. [VO(OPri)3] (10 g, 41 mmol) was added
dropwise giving a red precipitate that was filtered off in air, washed
with ether, and Soxhlet extracted under dinitrogen with hot acetonitrile
(∼150 cm3) until a small green residue remained (∼4 h). Ether (150
cm3) was added to the cooled extract, and it was kept at -20 °C for 1
Preparation of {V(NS3)}n (5). (a) Method A. 6 (0.41 g,1 mmol)
was refluxed for 10 min in methanol, giving a dark-green precipitate
that was filtered off from the cooled solution, washed with ether, and
dried in vacuo (0.20 g, 0.82 mmol, 82%). Anal. Calcd for C6H12NS3V:
C, 29.4; H, 4.9; N, 5.7. Found: C, 29.4; H, 4.8; N, 6.2.
(b) Method B. 1 (0.21 g, 0.8 mmol) and diethylaluminum ethoxide
(1 mL of 1.6 M toluene solution) were refluxed in acetonitrile (25 cm3)
for 30 min, then filtered hot. The resulting dark-green precipitate (0.06
g) was washed with hot acetonitrile and ether and dried in vacuo. It
had an IR spectrum identical to that of 5 as prepared above.
(35) Chatt, J.; Dilworth, J. R.; Richards, R. L. Chem. ReV. 1978, 78, 589.
(36) Glaser, M.; Spies, H.; Lu¨ger, T.; Hahn, F. E. J. Organomet. Chem.
1995, 503, C32.
(37) Chatt, J.; Crichton, B. A. L.; Dilworth, J. R.; Dahlstrom, P.; Gutkoska,
R.; Zubieta, J. Inorg. Chem. 1982, 21, 2383.
(38) Evans, D. F. J. Chem. Soc. 1958, 2003.
(39) Ward, K. J. Am. Chem. Soc. 1935, 57, 914.
(40) Harley-Mason, J. J. Chem. Soc. 1947, 320.
(41) Barbaro, P.; Bianchini, C.; Scapacci, G.; Masi, D.; Zanello, P. Inorg.
Chem. 1994, 33, 3180.

Vanadium Complexes
Inorganic Chemistry, Vol. 39, No. 16, 2000 3495
(c) Method C. NS3H3 (0.3 cm3, 1.52 mmol) and BunLi (3 cm3, 4.5
mmol) were added simultaneously via a syringe to a solution of [VCl3-
(THF)3] (0.5 g, 1.34 mmol) in THF (80 cm3). There was an immediate
reaction to give a deep-brown solution, which was taken to dryness in
a vacuum to leave a green-brown solid that was washed with ether,
dried, and had an IR spectrum identical to that of 5 as prepared above
(0.20 g, 0.82 mmol, 63%). Anal. Calcd for C6H12NS3V: C, 29.4; H,
4.9; N, 5.7. Found: C, 28.3; H, 4.8; N, 6.2.
Preparation of [V(NS3)(C6H11NC)] (8c). Compound 6 (0.68 g, 2.5
mmol) was refluxed in tetrahydrofuran (40 cm3) and cyclohexyl
isocyanide (1.0 cm3) for 4 h. The solution was cooled and filtered.
The filtrate was reduced in vacuo to 10 cm3, ether (30 cm3) was added,
and the brown product (0.64 g, 72%) that precipitated was collected,
washed with ether, and dried in vacuo. Anal. Calcd for C13H23N2S3V:
C, 44.1; H, 6.5; N, 7.9. Found: C, 43.8; H, 6.4; N, 8.1. µeff ) 2.74µB.
IR (Nujol): 2173 cm-1 (s, νNC).
Preparation of [V(NS3)(NH3)] (6). 4 (0.30 g, 1.1 mmol) was heated
to reflux in acetonitrile (10 cm3) and filtered from a small green residue.
Yellow crystals (0.14 g, 0.53 mmol, 48% yield), suitable for X-ray
studies, crystallized on cooling overnight. They were washed with
acetonitrile and ether and dried in vacuo. Anal. Calcd for
C6H15N2S3V: C, 27.5; H, 5.7; N, 10.7. Found: C, 27.8; H, 5.8; N,
11.1. µeff ) 2.70µB. IR (Nujol mull): 3255, 3216, 3190, 3142 cm-1
(m, νNH).
Preparation of Et4N[V(NS3)Cl] (7a). Tetraethylammonium chloride
hydrate (4.5 g, ∼25 mmol) was dried in vacuo at 100 °C for 2 h, then
mixed with 4 (5.55 g, 20 mmol). Acetonitrile (300 cm3) was added
and the mixture refluxed for 20 min, giving a red solution that was
filtered hot from a small yellow residue and cooled to room-temperature
overnight, then at -20 °C for 2 nights. Pink crystals suitable for X-ray
studies were filtered off, washed with acetonitrile and ether, and dried
in vacuo (6.95 g, 16.9 mmol, 84%). Anal. Calcd for C14H32ClN2S3V:
C, 40.9; H,7.8; N, 6.8. Found: C, 40.9; H,7.7; N, 6.9. µeff ) 2.91µB.
Preparation of Ph4P[V(NS3)Cl] (7b). [Ph4P]Cl (0.6 g,1.6 mmol)
was added to the solution formed by heating 4 (0.55 g 2 mmol) in
MeCN (40 cm3) to reflux and filtering. The [Ph4P]Cl dissolved, and a
brown precipitate was formed. After 2 h this was filtered off, washed
with ether, and dried in vacuo (0.96 g,1.55 mol, 78%). Anal. Calcd for
C30H32ClN2PS3V: C, 58.1; H, 5.2; N, 2.3. Found: C, 58.1; H, 6.0; N,
2.2.
Preparation of [V(NS3)(NSiMe3)] (9). Compound 4 (4.44 g, 16
mmol) was suspended in a mixture of CH3CN (160 cm3) and
trimethylsilyl azide (40 cm3, 35 g, 0.320 mmol). The mixture was heated
to reflux, and the initial yellow suspension became a dark-red solution
over 3 h. It was cooled to 20 °C and filtered, leaving a small residue.
The filtrate was refluxed overnight, then cooled to 20 °C and filtered,
leaving no residue. The new filtrate was taken to dryness in vacuo,
leaving a yellow residue that was taken up in CH3CN (64 cm3), refluxed
for 1 h, and then filtered hot. The filtrate deposited brown-yellow
crystals (suitable for X-ray study) on cooling at -20 °C overnight.
Yield, 4.00 g, (12 mmol, 75%). Anal. Calcd for C9H21N2S3SiV: C,
32.5; H, 6.3; N, 8.4. Found: C, 32.9; H, 6.1; N, 8.7. 1H NMR
(CDCl3): ∂ 0.47 (s, 9H, SiCH3), 3.33 (m, 6H, NCH2CH2S), 3.65 (m,
6H, NCH2CH2S). 51V NMR (CD3CN): ∂ 349 (fwhm ) 560 Hz).
Preparation of [V(NS3)(NH)] (10). Compound 9 (1.33 g, 4 mmol)
was suspended in methanol (20 cm3) and acetonitrile (20 cm3)
containing four drops of water and heated to reflux. The yellow crystals
quickly changed to a red powder; after 1 h the mixture was cooled at
-20 °C and the resulting powdery precipitate filtered off and washed
with ether (yield 0.91 g, 3.5 mmol, 88%). Crystals suitable for an X-ray
study were obtained by recrystallization from acetonitrile. Anal. Calcd
for C6H13N2S3V: C, 27.7; H, 5.0; N, 10.8. Found: C, 27.9; H, 5.0; N,
1
11.1. H NMR (CDCl3): ∂ 0.08(s, NH), 3.49 (m, 6H, NCH2CH2S),
3.71 (m, 6H, NCH2CH2S). 51V NMR (CD3CN): ∂ 210 (fwhm ) 310
Hz). IR (Nujol): 3254 cm-1 (m, νNH).
Preparation of Et4N[V(NS3)Br] (7c). The preparation of 7c was
similar using [Et4N]Br (0.21 g, 1 mmol) and 4 (0.27 g, 1 mmol) in
MeCN (10 cm3). Brown crystals (0.18 g, 0.4 mmol, 40%) were obtained
on cooling the solution and a further 0.13 g (0.3 mmol, 30%) on adding
ether (30 cm3). Anal. Calcd for C14H32BrN2S3V: C, 36.9; H, 7.1; N,
6.2. Found: C, 36.5; H, 6.7; N, 6.7. µeff ) 2.74µB.
Preparation of [V(NS3)(NCPh3)] (11). Trityl chloride (0.48 g, 1.67
mmol) was dried at 100 °C in vacuo for 30 min and then added to 9
(0.55 g, 1.67 mmol) in MeCN (10 cm3). The solution was refluxed for
3 h, a red precipitate gradually forming. The mixture was then cooled,
and the precipitate was filtered off, washed with ether, and dried in
vacuo (0.30 g, 0.55 mmol, 33%). Anal. Calcd for C25H27N2S3V: C,
59.7; H, 5.4; N, 5.6. Found: C, 59.5; H, 5.4; N, 5.3. 1H NMR
(CDCl3): ∂ 3.40 (m, 6H, NCH2CH2S), 3.65 (m, 6H, NCH2CH2S), 7.4-
7.55 (m, 15H, Ph). 51V NMR (CD3CN): ∂ 234 (fwhm ) 1000 Hz).
Preparation of [V(NS3){NLi(THF)2}] (12). Compound 10 (0.13
g, 0.5 mmol) was stirred in tetrahydrofuran (5 cm3), and lithium
diisopropylamide (0.3 cm3 of 2.0 M solution, 0.6 mmol) was added,
giving a yellow solution. This was filtered and ether (20 cm3) added to
the filtrate as a layer. Yellow crystals came out of solution overnight;
they were filtered off, washed with ether, and dried in vacuo (0.05 g,
0.12 mmol, 24%). Anal. Calcd for C14H28N2O2S3LiV: C, 41.0; H, 6.8;
N, 6.8. Found: C, 40.2; H, 7.1; N, 7.1.
Preparation of Bun N[V(NS3)Br] (7d). Preparation of 7d was
4
similar using [Bun N]Br (0.62 g) and 4 (0.66 g, 2.4 mmol). The filtrate
4
was reduced to dryness in vacuo, the residue was dissolved in MeCN
(5 cm3), and then ether (20 cm3) was added, giving an oil (0.09 g, 0.16
mmol, 7%) that crystallized at -20 °C. Anal. Calcd for C22H48-
BrN2S3V: C, 46.6; H, 8.5; N, 4.9. Found: C, 46.1; H, 8.5; N, 4.9.
Preparation of Et4N[V(NS3)(N3)] (7e). Preparation of 7e was similar
from [Et4N]N3 (0.75 g, 4.4 mmol) and 4 (1.12 g, 4 mmol) in MeCN
(20 cm3), giving 1.10 g (2.6 mmol, 66%) of red crystals. Anal. Calcd
for C14H32N5S3V: C, 40.3; H, 7.7; N, 16.8. Found: C, 40.5; H, 7.8; N,
17.1. µeff ) 2.53µB. IR (Nujol): 2056 cm-1 (s, νN3).
Preparation of Et4N[V(NS3)(CN)] (7f). Preparation of 7f was
similar from [Et4N]CN (1.25 g, 8 mmol) and 4 (2.08 g, 7.5 mmol) in
MeCN (150 cm3), giving 1.66 g (4.15 mmol, 55%) of yellow crystals.
Anal. Calcd for C15H32N3S3V: C, 44.9; H, 8.0; N, 10.5. Found: C,
45.1; H, 8.1; N, 10.5. µeff ) 2.67µB. IR: 2094 cm-1 (s, νCN).
Preparation of [V(NS3)(MeCN)] (8a). Compound 4 (0.68 g 2.5
mmol) was refluxed in tetrahydrofuran (40 cm3) for 2 h, cooled, and
filtered into acetonitrile (10 cm3). After 3 days the solution was taken
to dryness; the residue showed IR bands characteristic of the ammine,
so it was refluxed with acetonitrile for 20 min and filtered hot and the
filtrate taken to dryness, giving the pure product (0.31 g, 1.1 mmol,
44%). Anal. Calcd for C8H15N2S3V: C, 33.6; H, 5.2; N, 9.8. Found:
C, 33.5; H, 5.3; N, 9.9. µeff ) 2.78µB. IR (Nujol): 2264 cm-1 (s, νCN).
Preparation of [V(NS3)(ButNC)] (8b). Compound 6 (0.68 g, 2.5
mmol) was refluxed in tetrahydrofuran (40 cm3) for 2 h, then cooled
and filtered. tert-Butyl isocyanide (1 cm3) was added, giving an orange
solution that was refluxed for 1 h and then filtered cold. The filtrate
was reduced in vacuo to 10 cm3, ether (10 cm3) was added, and the
brown product (0.32 g, 1.0 mmol, 40%) that precipitated was collected,
washed with ether, and dried in vacuo. Anal. Calcd for C11H21N2S3V:
C, 40.2; H, 6.4; N, 8.5. Found: C, 40.2; H, 6.5; N, 8.5. µeff ) 2.66µB.
IR (Nujol): 2173 cm-1 (s, νNC).
Preparation of [V(NS3)(NPh)] (13a). (a) Method A. Phenyl
isocyanate (2 cm3, excess) was added to 1 (0.26 g, 1 mmol). The mixture
was heated gradually to 150 °C (using a silicone oil bath) when
effervescence took place, and the purple color changed to a deep red-
orange. After 1 h the mixture was cooled overnight. Orange crystals
formed; they were filtered off, washed with phenyl isocyanate and ether,
and then dried in vacuo (0.30 g, 0.90 mmol, 90%).
(b) Method B. Aniline (2 cm3, excess) was added to 1 (0.26 g, 1
mmol). The mixture was heated to reflux (180 °C) under a stream of
dinitrogen and held at reflux for 20 min. The purple color changed to
a deep red-orange. The mixture was allowed to cool and filtered cold,
leaving a small residue. Diethyl ether (10 cm3) was added as a layer to
the filtrate; orange crystals formed overnight. They were filtered off,
washed with diethyl ether, and dried in vacuo (0.10 g, 0.30 mmol, 30%).
Anal. Calcd for C12H17N2S3V: C, 42.9; H, 5.1; N, 8.3. Found: C, 43.1;
1
H, 5.0; N, 8.2. H NMR (CD2Cl2): ∂ 3.43 (m, 6H, NCH2CH2S), 3.66
(m, 6H, NCH2CH2S), 7.19-7.71 (m, 5H, Ph). 51V NMR (CD3CN): ∂
321 (fwhm ) 580 Hz).
The following complexes were prepared as for 13a, method A, above.
Because some of the isocyanates are solids, 2-methoxyethyl ether (2

3496 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
1
cm3) was added to each preparation and reactions were carried out at
the boiling point of this solvent (160 °C).
7.3; N, 6.5; S, 15.2. H NMR (CDCl3): ∂ 1.12 [6H CH(CH3)2, J 6.8
Hz], 3.20 [1H, CH(CH3)2, J 6.8 Hz], 3.01 [6H N(CH3)2], 3.46 (SCH2),
4.14 (OCH), 4.60 (OCH′), 6.82(4-Ph), 6.95(3-Ph). 13C NMR (CDCl3):
∂ 23.4 [CH(CH3)2], 26.2 [CH(CH3)2], 32.2 (SCH), 43.8 (NCH), 74.5
(OCH), 120.9 (4-Ph), 122.3(3-Ph), 135.2 (2-Ph), 165.1 (OPh). 51V NMR
(CD3CN): ∂ 269 (fwhm ) 630 Hz).
[V(NS3)(NC6H4OMe-4)] (13b). Anal. Calcd for C13H19N2OS3V: C,
1
42.6; H,5.2; N, 7.7. Found: C, 42.8; H, 5.2; N,7.6. H NMR (CD2-
Cl2): ∂ 3.40 (m, 6H, NCH2CH2S), 3.63, (m, 6H, NCH2CH2S), 3.79 (s,
3H OCH3), 7.69 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 335 (fwhm )
810 Hz).
(b) Method B. The use of Me3SiNHNMe2 instead of NH2NMe2 and
following the procedure described in method A gave compound 15. It
was identified by elemental analysis, IR, 1H NMR, and the crystal cell
parameters (see below).
[V(NS3)(NC6H4Me-4)] (13c). Anal. Calcd for C13H19N2S3V: C, 44.6;
1
H, 5.4; N, 8.0. Found: C, 46.1; H, 5.4; N, 8.1. H NMR (C2DCl2): ∂
2.45 (m, 3H CH3), 3.50 (m, 6H, NCH2CH2S), 3.72 (m, 6H, NCH2CH2S),
7.20-7.68 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 325 (fwhm ) 710 Hz).
[V(NS3)(NC6H4Cl-4)] (13d). Anal. Calcd for C12H16ClN2S3V: C,
Synthesis of [V(OS2)O(NSiMe3)(dipp)] (16). A mixture of com-
pound 14 (0.5 g, 1.31 mmol) and (Me3Si)2NH (0.84 g, 5.25 mmol) in
CH3CN (50 cm3) was heated under reflux for 12 h followed by stirring
for a further 12 h at room temperature. The red-orange solution was
filtered, and the solvent was removed in vacuo. The brown oily residue
was extracted with hexane (60 cm3), and then the extract was
concentrated to half the volume and left to crystallize at room
temperature. After 1 week, light-orange prismatic-shaped crystals
suitable for X-ray structure determination were filtered off and dried
under vacuum (20%). Anal. Calcd for C19H34NO2S2SiV: C, 50.5; H,
7.6; N, 3.1; S, 14.2. Found: C, 49.8; H, 7.3; N, 3.0; S, 14.6. 1H NMR
(CDCl3): ∂ 0.04 [9H, NSi(CH3)3], 1.15 [6H CH(CH3)2, J 6.8 Hz], 3.25
[1H, CH(CH3)2, J 6.8 Hz], 3.60 (SCH), 3.61 (SCH′), 4.07 (OCH), 4.55
(OCH′), 6.87(4-Ph), 6.97(3-Ph). 13C NMR (CDCl3): ∂ 0.5 [NSi(CH3)2],
23.1 [CH(CH3)2], 26.2 [CH(CH3)2, 33.3 (SCH), 72.8 (OCH), 121.9 (4-
Ph), 122.9(3-Ph), 134.0 (2-Ph), 166.0 (OPh). 51V NMR (CD3CN): ∂
61 (fwhm ) 365 Hz).
1
38.9; H, 4.3; N, 7.6. Found: C, 39.2; H, 4.2; N, 7.7. H NMR (C2-
DCl2): ∂ 3.43 (m, 6H, NCH2CH2S), 3.63 (m, 6H, NCH2CH2S), 7.30-
7.65 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 331 (fwhm ) 890 Hz).
[V(NS3)(NC6H4Br-4)] (13e). Anal. Calcd for C12H16BrN2S3V: C,
1
34.7; H, 3.9; N, 6.7. Found: C, 34.8; H, 3.8; N, 7.2. H NMR (C2-
DCl2): ∂ 3.46 (m, 6H, NCH2CH2S), 3.67 (m, 6H, NCH2CH2S), 7.47-
7.59 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 331 (fwhm ) 850 Hz).
[V(NS3)(NC6H4NO2-4)] (13f). Anal. Calcd for C12H16N3O2S3V: C,
1
37.8; H, 4.2; N, 11.0. Found: C, 39.8; H, 4.5; N, 10.6. H NMR (C2-
DCl2): ∂ 3.43 (m, 6H, NCH2CH2S), 3.63 (m, 6H, NCH2CH2S), 7.30-
7.65 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 355 (fwhm ) 1500 Hz).
[V(NS3)(NC6H4OMe-3)] (13 g). Anal. Calcd for C13H19N2OS3V:
C, 42.6; H, 5.2; N, 7.7. Found: C, 42.9; H, 5.2; N, 8.2. 1H NMR (CD2-
Cl2): ∂ 3.52 (m, 6H, NCH2CH2S), 3.73 (m, 6H, NCH2CH2S), 3.79 (s,
3H OCH3), 6.86-7.41 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 322 (fwhm
) 760 Hz).
Synthesis of [V(OS2)1.5O] (17). To a hexane solution (30 cm3) of
O(CH2CH2SH)2 (0.88 g, 6.36 mmol) was added [VO(OPri)3] (1.035 g,
4.24 mmol), and the mixture was stirred for 12 h at room temperature.
The resulting olive-yellow solid precipitate was filtered off, washed
with hexane (3 × 10 cm3), and dried in vacuo (87%). Anal. Calcd for
C6H12O2.5S3V: C, 26.57; H, 4.46; S, 35.45. Found: C, 26.00; H, 4.21;
S, 34.95. Compound 17 is diamagnetic.
[V(NS3)(NC6H4Cl-3)] (13h). Anal. Calcd for C12H16ClN2S3V: C,
1
38.9; H, 4.3; N, 7.6. Found: C, 38.9; H, 4.4; N, 6.9. H NMR (CD2-
Cl2): ∂ 3.56 (m, 6H, NCH2CH2S). 3.76 (m, 6H, NCH2CH2S), 6.8-
7.69 (m, 4H, Ph). 51V NMR (CD3CN): ∂ 328 (fwhm ) 760 Hz).
[V(NS3)(NC6H3Me2-3,4)] (13i). Anal. Calcd for C14H21N2S3V: C,
1
46.2; H, 5.8; N, 7.7. Found: C, 46.5; H, 5.7; N, 8.4. H NMR (CD2-
Cl2): ∂ 2.19 (m, 3H, CH3), 2.28 (m, 3H, CH3), 3.40 (m, 6H,
NCH2CH2S), 3.63 (m, 6H, NCH2CH2S), 7.20-7.68 (m, 3H, Ph). 51V
NMR (CD3CN): ∂ 325 (fwhm ) 890 Hz).
Synthesis of [V(OS2)(NNMe2)(OSiMe3)] (18). A mixture of com-
pound 17 (0.21 g, 1.03 mmol) and Me3SiNHNMe2 (0.55 g, 4.15 mmol)
in CH3CN (20 cm3) was stirred for 24 h at room temperature, and then
the solvent was stripped off to remove volatile products. The residue
was redissolved in CH3CN (20 cm3) and filtered, and the filtrate, after
concentration to 10 cm3, was left to crystallize at 4 °C for 2 days.
Burgundy, X-ray-quality crystals precipitated, which were filtered,
washed with cold hexane (4 °C) (3 × 2 cm3), and dried in vacuo (80%).
Anal. Calcd for C9H23N2O2S2SiV: C, 32.3; H, 6.9; N, 8.4; S, 19.2.
[V(NS3)(NC6H3Cl2-3,4)] (13j). Anal. Calcd for C12H15Cl2N2S3V: C,
1
35.6; H, 3.7; N, 6.9. Found: C, 35.7; H, 3.6; N, 7.3. H NMR (CD2-
Cl2): δ 3.46 (m, 6H, NCH2CH2S), 3.69 (m, 6H, NCH2CH2S), 7.40-
7.81 (m, 3H, Ph). 51V NMR (CD3CN): ∂ 337 (fwhm ) 710 Hz).
[V(NS3)(NC6H11)] 13k. Anal. Calcd for C12H23N2S3V: C, 42.1; H,
6.7; N, 8.2. Found: C, 43.4; H, 6.7; N,7.9. 1H NMR (CD2Cl2): ∂ 1.88-
2.24 (m, 11H, C6H11), 3.42 (m, 6H, NCH2CH2S), 3.62 (m, 6H,
NCH2CH2S). 51V NMR (CD3CN): ∂ 194 (fwhm ) 730 Hz).
1
Found: C, 31.8; H, 6.4; N, 8.0; S, 20.1. H NMR (CDCl3): ∂ 0.08
[9H, OSi(CH3)2], 3.28 (SCH, J 5.6), 3.55 [N(CH3)2], 3.91 (OCH, J
5.6, 9.3), 4.41 (OCH′, J 5.6, 9.3). 13C NMR (CDCl3): ∂ 2.4 [OSi-
(CH3)2], 31.7 (SCH2), 44.9 [N(CH3)2], 74.2 (OCH). 51V NMR (CD3-
CN): ∂ 254 (fwhm ) 530 Hz).
Synthesis of [V(OS2)O(dipp)] (14). To a hexane solution (30 cm3)
of O(CH2CH2SH)2 (0.58 g, 4.24 mmol) and HOC6H3Pri2-2,6 (0.76 g,
4.24 mmol) at room temperature was added [VO(OPri)3], and the
mixture was stirred for 10 min. The color changed to orange-red. Next,
the solvent was removed in vacuo, the resulting oily residue was
redissolved in CH3CN (10 cm3) and filtered, and the filtrate was left at
4 °C for 4 days. The resulting dark-red cubic-shaped crystals suitable
for X-ray structure determination were collected by filtration, washed
with cold hexane (4 °C), and dried in vacuo (82%). Anal. Calcd for
C16H25O3S2V: C, 50.5; H, 6.6; S, 16.9. Found: C, 49.9; H, 6.5; S,
Quantitative Study of Preparation of Compound 4. Compound
1 (0.5 mmol), anhydrous hydrazine (4.88 mmol), and THF (10 cm3)
were degassed and sealed under vacuum in a glass vessel equipped
with a break seal. The mixture was stirred for 3 h at 20 °C, giving a
pale yellow-green solution and a yellow solid residue. The vessel was
then cooled to -196 °C and opened at the break seal, and the evolved
gas was pumped into a calibrated system by means of a To¨pler pump
and shown to be N2 by mass spectrometry (0.22 mmol). The solution
was then warmed, and the volatile NH3 and N2H4 were first distilled
into H2SO4. Then this solution was distilled from KOH solution in an
all-glass apparatus into H2SO4. The NH3 and N2H4 content of this
solution (negligible and 4.10 mmol, respectively) was then determined
by standard color tests.34,35 The yellow solid was filtered off and shown
to be 4 (IR spectrum identical to an authentic sample) (0.49 mmol).
The remaining reaction solution was also taken to dryness in a vacuum
and, after distillation from base and color tests as above, shown to
contain no further NH3 or N2H4.Thus, the total yield of recovered
dinitrogen was 4.81 mmol (98.5% recovery) and the overall stoichi-
ometry of the reaction was in accord with the reaction sequence, 1a f
1b f 1c of Scheme 1.
1
16.3. IR (Nujol): 982 cm-1 (s, νVO). H NMR (CDCl3): ∂ 1.18 [6H
CH(CH3)2, J 6.8 Hz], 3.19 [1H, CH(CH3)2), J 6.8 Hz], 3.79 (SCH),
3.87 (SCH′), 4.08 (OCH), 4.68 (OCH′), 6.96(4-Ph), 7.00(3-Ph). 13C
NMR (CDCl3): ∂ 23.0 [CH(CH3)2], 26.2 [CH(CH3)2], 35.4 (SCH), 72.8
(OCH), 123.7(4-Ph), 122.7(3-Ph), 135.0 (2-Ph), 165.0 (OPh). 51V NMR
(CD3CN): ∂ 191.0 (fwhm ) 58 Hz).
Synthesis of [V(OS2)O(NNMe2)(dipp)] (15). (a) Method A. To a
solution of compound 14 (0.91 g, 2.39 mmol) in CH3CN (30 cm3) was
added NH2NMe2 (0.58 g, 9.57 mmol), and the reaction mixture was
stirred for 24 h. Next, the solvent was stripped off under vacuum to
remove any excess of NH2NMe2. The residue was extracted with CH3-
CN (20 cm3), and the extract was filtered. The filtrate was left to
crystallize at 4 °C for 3 days. Dark-red cubic-shaped crystals suitable
for X-ray structure determination were collected by filtration, washed
with cold hexane (4 °C), and dried in vacuo (55%). Anal. Calcd for
C18H31N2O2S2V: C, 51.2; H, 7.4; N, 6.7; S, 15.2. Found: C, 51.0; H,
Thermal Decomposition/Disproportionation of [V(NS3)(NH2NH2)]
(4). Compound 4 (0.495 mmol, containing 0.99 mol N) was sealed
under vacuum at -196 °C with THF (20 cm3) and MeOH (5 cm3) in

Vanadium Complexes
Inorganic Chemistry, Vol. 39, No. 16, 2000 3497
a glass vessel equipped with a break-seal. The mixture was heated for
1 h at 75 °C, giving a green solution and a green solid residue. The
evolved gas was collected and shown to be N2 by mass spectrometry
(0.144 mmol, 0.288 mol N). The solution was then warmed, and the
volatile NH3 and N2H4 were determined (0.572 mmol, 0.572 mol N,
and negligble, respectively). The remaining reaction solution was also
taken to dryness in a vacuum and shown to have contained further
NH3 (0.096 mmol, 0.096 mol N). Thus, the total yield of recovered
nitrogen was 0.956 mol N (96.5% yield based on 4), and the overall
stoichiometry of the reaction was in accord with reactions 2 and 3 above
occurring consecutively.
calculated positions, with isotropic temperature factors riding on the
Ueq or Uiso values of the parent carbon atoms. In the ammine ligand,
hydrogen atoms were located in difference Fourier maps and included
in the refinement process with geometrical constraints. Calculation of
the Flack parameter both for the results quoted and for the inverse
structure indicated that for the crystal chosen the absolute structure is
correct. At the conclusion of the refinement, wR2 ) 0.093 and R1 )
0.08543 for the 1170 reflections weighted w ) σ-2(Fo ); for the
2
“observed” data only, R1 ) 0.049.
In the final difference map, the highest peaks (ca 0.35 e Å-3) were
close to the ammine nitrogen atom.
Study of Reaction of 4 with [NEt4]Cl. Compound 4 (0.53 mmol),
[NEt4]Cl‚H2O (∼1 mmol), and MeCN were sealed under vacuum in
an all-glass vessel equipped with a break-seal and stirred for 1 h at 20
°C. Workup as for the thermal decomposition reaction above gave
compound 7a (0.41 mmol, 78%), NH3 (0.06 mmol), and N2H4 (0.51
mmol, 96%). Thus, the reaction proceeds according to eq 6 above,
essentially quantitatively.
Attempted Reduction of Compound 4. Compound 4 (0.25 mmol),
dipp (5 mmol), and amalgamated zinc (2.5 mmol) were sealed in a
100 cm3 flask under argon via a septum. Then THF (10 cm3) was added
via a syringe and the mixture stirred for 72 h. Next H2SO4 (10 cm3 of
0.5 M solution) was injected, and after the mixture was stirred, an excess
of concentrated NaOH solution was added. The mixture was distilled
into dilute H2SO4 and the resulting solution tested for ammonia as
described above, giving 0.042 mmol NH3, which was close to values
obtained from blank runs without 4 being present. Repeating the reaction
at 66 °C for 1 h gave NH3 (0.34 mmol). This yield (due to the
disproportionation reaction of 4 described above) was the same as that
obtained from blanks without Zn/dipp added.
Scattering factors for neutral atoms were taken from ref 44. Computer
programs used in this analysis have been noted above or in Table 4 of
ref 45 and were run on a DEC AlphaStation 200 4/100 in the Nitrogen
Fixation Laboratory, John Innes Centre.
[V(NS3)(NNMe2)], complex 2b, crystallizes as red, rectangular
prisms. One was sealed in a glass capillary under a dinitrogen stream,
then mounted on a KUMA KM-4 four-circle diffractometer (with
monochromated Mo KR radiation)46 for determination of accurate cell
parameters (from the settings of 25 reflections, θ ) 8.5-13°, each
centered in four orientations) and for measurement of diffraction
intensities (1218 unique reflections to θmax ) 25°; 1118 were “observed”
with I > 2σI).
Corrections were applied for Lorentz polarization effects; no
correction for crystal deterioration was necessary. The structure was
determined by direct methods in SHELXS42 and refined by full-matrix
least-squares methods, on F2’s, in SHELXL.43 The carbon-bonded
hydrogen atoms were included in calculated positions and refined using
a riding model. An absorption correction, using DIFABS4,47 was tried
but gave no significant differences and so was rejected. At convergence,
R1 and wR2 were 0.032 and 0.087 for the 1118 “observed” data
Attempted Reduction of Hydrazide Complexes. We attempted to
protonate the hydrazide ligands in compounds 2b and 2c with halogen
acid and to reduce them with Zn/HOC6H3Pri2-2,6 (Hdipp) using
conditions similar to those tried with 4 above, but neither protonation
nor reduction was observed.
2
weighted w ) [σ2(Fo ) + (0.046P)2 + 0.56P]-1 with P ) (Fo2 + 2Fc2)/
3. In the final difference map, the highest peaks were ca 0.36 e Å-3
and were in the thiolate ligand.
Many crystals from several preparations of [V(NS3)(N2H4)], complex
4, were examined. Preliminary photographs showed all the samples to
be multiple crystals and to have alternate sharp and “blurry” festoons
on Weissenberg photographs. Eventually, a twinned crystal, with a
major and minor component, with relatively little “blurriness”, was
found and transferred to the diffractometer. By use of the composite
cell of both twins in the crystal, which looked satisfactory at least for
the lower layers, intensities were measured and corrected as usual, and
the structure was detemined readily by direct methods showing two
independent molecules (of the major twin) in the asymmetric unit. After
some refinement, examination of the major difference peaks showed
the corresponding pair of molecules of the minor twin. Non-hydrogen
atoms of the major twin were refined anisotropically with hydrogen
atoms included in the NS3 ligand, all parameters riding on those of the
parent carbons. The minor twin was refined with some constrained bond
dimensions, and only the V and S atoms allowed anisotropic thermal
parameters. Refinement of the four molecules and their occupation ratio,
0.816(6):0.184, gave remarkably good results, with good agreement in
the dimensions between the major molecules and with those of similar
molecules (see Table 1). The R factors are not as low as we would
normally like to present, but we believe that the structure is reliable.
Further analysis of the twinning, we suggest, would not give signifi-
cantly better results, since the “blurriness” along the festoons of
reflections would still yield inadequacies in the measurement of
diffraction intensities.
Conversion of Complex 10 into Complex 1. Compound 10 (0.5
mmol), MeOH (10 cm3), and [NMe4]OH (1 mmol) were heated at reflux
for 5 min. The resulting red solution was cooled and filtered, and HCl
(0.5 mmol) in Et2O (0.5 cm3) was added to give an immediate purple
precipitate, which was filtered off, dried in vacuo, and identified as 1
by its IR spectrum (0.06 g, 45%).
Crystal Structure Analyses. The X-ray analyses were performed
in laboratories at both the John Innes Centre and University of Wroclaw.
Typical procedures from each laboratory are described, together with
exceptional features in some other analyses, and all experimental data
are collated in Tables 2 and 3.
Crystals of [V(NS3)(NH3)], complex 6, are yellow, translucent plates.
One, ca 0.40 mm × 0.08 mm × 0.05 mm, was mounted on a glass
fiber. After preliminary photographic examination, this was transferred
to an Enraf-Nonius CAD4 diffractometer (with monochromated radia-
tion) for determination of accurate cell parameters (from the settings
of 25 reflections, θ ) 10-11°, each centered in four orientations) and
for measurement of diffraction intensities (1175 unique reflections to
θmax ) 25°; 729 were “observed” with I > 2σI). Subsequently,
measurements of five reflections were considered suspect, and these
reflections were removed from the data set.
During processing, corrections were applied for Lorentz polarization
effects and absorption (by semiempirical ψ scan methods) and to
eliminate negative net intensities (by Bayesian statistical methods). A
small deterioration correction was also applied. The structure was
determined by the automated Patterson routines in the SHELXS
program42 and refined by full-matrix least-squares methods, on F2’s,
in SHELXL.43 There is disorder in the NS3 ligand, with the occupancy
ratio of the major component to its mirror image component of ca
4:1; the thermal parameters of the major component atoms were refined
anisotropically, those in the minor component isotropically. Hydrogen
atoms were included on this ligand in both components, in geometrically
(NEt4)[V(NS3)Cl], complex 7a, is isostructural with the iron ana-
logue11 and shows the same patterns of disorder in both cation and
anion. The NS3 anion lies disordered about a mirror plane, with several
atoms lying in the plane and some of the ligand atoms lying on one
side or the other of that plane. The cation is disordered in two major
(44) International Tables for X-ray Crystallography; Kluwer Academic
Publishers: Dordrecht, 1992; Vol. C, pp 500, 219, and 193.
(45) Anderson, S. N.; Richards, R. L.; Hughes, D. L. J. Chem. Soc., Dalton
Trans. 1986, 245.
(46) Kuma KM-4, version 6.1; Kuma Diffraction: Wroclaw, Poland, 1996.
(47) Walker, N.; Stuart, D. Acta Crystallogr. 1983, A39, 158.
(42) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(43) Sheldrick, G. M. SHELXLsProgram for crystal structure refinement,
University of Go¨ttingen, 1993.

3498 Inorganic Chemistry, Vol. 39, No. 16, 2000
Davies et al.
and two minor orientations about a 2-fold symmetry axis; site
occupancies of the â-carbon atoms, after refinement, range from 0.06
to 0.5. Hydrogen atoms in the anion were included in idealized
positions, and their isotropic temperature factors were allowed to refine
freely. In the cation, difference peaks at ca 1.9 Å from the central
nitrogen atom were included as hydrogen atoms with full site occupancy
(assumed to be coincidence of atoms from molecules in several
orientations) with all positional and thermal parameters refining freely.
The non-hydrogen atoms of the anion, and the nitrogen atom of the
cation, were refined anisotropically.
Acknowledgment. We thank the British Council, the Polish
State Committee for Scientific Research, and the BBSRC for
support. We also thank Dr. S. A. Fairhurst for NMR spectro-
scopic measurements.
Supporting Information Available: Tables listing fractional
coordinates, anisotropic thermal parameters, hydrogen atom parameters,
bond lengths, and bond angles. Additional data are also available in
CIF format. This material is available free of charge via the Internet at
http://pubs.acs.org.
Crystals of [V(NS3)(NSiMe3)], complex 9, were analyzed indepen-
dently in both laboratories; data from both are presented here as
structures 1 and 2 and are seen to be very similar.
IC9909476