Reactions of transition-metal nitrido compounds with B(C6F5)3: Crystal structure of [Re{NB(C6F5)3}(PMe2Ph)(S 2CNMe2)2]

Article abstract of DOI:10.1039/a805425h

The transition-metal nitrido complexes [Re(N)(PR₃)(S₂CNR′₂)₂] (PR₃ = PMe₂Ph, R′ = Me; PR₃ = PMePh₂, R′ = Et 1), [Re(N)(Cl)(PMePh₂)₂(S₂

Full text of DOI:10.1039/a805425h

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Reactions of transition-metal nitrido compounds with B(C6F5)3 :
crystal structure of [Re{NB(C6F5)3}(PMe2Ph)(S2CNMe2)2]
Linda H. Doerrer, Andrew J. Graham and Malcolm L. H. Green*
Inorganic Chemistry Laboratory, South Parks Road, Oxford, UK OX1 3QR.
E-mail: malcolm.green@chem.ox.ac.uk
Received 13th July 1998, Accepted 2nd October 1998
The transition-metal nitrido complexes [Re(N)(PR3)(S2CNRЈ2)2] (PR3 = PMe2Ph, RЈ = Me; PR3 = PMePh2, RЈ = Et
1), [Re(N)(Cl)(PMePh2)2(S2CNMe2)] 2, [Mo(N)(S2CNR2)3] (R = Me or Et) and [NBun ][Os(N)(1,2-S2C6H4)2] reacted
4
with the strong Lewis acid B(C6F5)3 to yield the adducts [Re{NB(C6F5)3}(PR3)(S2CNRЈ2)2] (PR3 = PMe2Ph, RЈ = Me
3*; PR3 = PMePh2, RЈ = Et 4), [Re{NB(C6F5)3}(Cl)(PMePh2)2(S2CNMe2)] 5, [Mo{NB(C6F5)3}(S2CNR2)3] (R = Me 6
or 7) and [NBun ][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8 (* indicates that the compound has been structurally characterised).
4
᎐
Reactions of 3, 6 and 8 with competing strong Lewis bases have revealed differences in the stability of the M᎐N–B
᎐
interaction depending on the steric crowding around the metal centre. Reaction of 8 with MeO3SCF3 causes the
formation of [Os{NB(C6F5)3}{1,2-(S)(SMe)C6H4}(1,2-S2C6H4)] 9.
Recently we have been exploring the varied chemistry of the
strong Lewis acid B(C6F5)3 which is crystalline and easily syn-
thesized. As well as mediating unusual and unexpected reac-
tions,1,2 it has been shown to form relatively stable adducts with
transition metal oxo complexes.3,4 Transition metal nitrido
complexes are another class of nucleophiles that might be
expected to react with strong Lewis acids; indeed reactions
between rhenium nitrido compounds and boron trihalides have
been reported.5,6 However, adducts with triarylboranes have
only previously been demonstrated by indirect reaction7 and
electrophilic attack at nitrido moieties bound to other metals
has been confined to carbocationic Lewis acids.8,9 We here
describe studies into the reactivity of B(C6F5)3 with transition
metal nitrido complexes.†
[Os{NB(C6F5)3}(1,2-S2C6H4)2] 8 respectively (Scheme 1). These
compounds are all highly soluble in dichloromethane but
virtually insoluble in hydrocarbon solvents and removal of
the excess of borane by washing thoroughly with hexanes was
generally sufficent to obtain analytically pure product. The
compounds 3–8 are reasonably air- and moisture-tolerant in
the solid state and can be stored indefinitely under an inert
atmosphere without decomposition. Yields were generally quite
high (ca. 60–90%).
Compounds 3–8 have been characterised by standard tech-
niques, namely 1H, 11B, 13C, 19F and 31P NMR and IR spectro-
scopies, microanalysis and, in the case of 3, 4 and 6, FAB (Fast
Atom Bombardment) mass spectrometry (Table 1). A single
crystal determination of compound 3 has been carried out;
crystals of 4 were also obtained but they proved to be of insuf-
ficient quality to obtain a properly refined structure although
the connectivity between atoms could be verified. As expected,
an upfield shift of the 11B-{1H} NMR spectroscopic resonance of
B(C6F5)3 (δ 51) to δ Ϫ3 to Ϫ6 is observed on adduct formation.
Results and discussion
The new rhenium() nitrido complexes [Re(N)(PMePh2)-
(S2CNEt2)2] 1 and [Re(N)(Cl)(PMePh2)2(S2CNMe2)] 2 were
prepared by reaction of [Re(N)Cl2(PMePh2)3]11 with 2 equiv-
alents of NaS2CNEt2ؒ3H2O and 1 equivalent of NaS2CNMe2ؒ
H2O respectively in refluxing methanol. The preparations used
were analogous to those used by Ritter and Abram12 to prepare
[Re(N)(PMe2Ph)(S2CNEt2)2] and [Re(N)(Cl)(PMe2Ph)2(S2-
CNMe2)]. Characterisation was undertaken by means of
microanalysis and IR and NMR spectroscopies; these data are
summarised in Table 1. Assignments were straightforward; the
This is consistent with the presence of a four-co-ordinate boron
᎐
species and hence with the expected formation of an M᎐N–B
᎐
dative bond. Infrared spectroscopy was in the main rather
᎐
uninformative as regards the strength of the M᎐N–B inter-
᎐
action since pentafluorophenyl groups display strong absorp-
tions in the range 900–1100 cmϪ1, preventing unambiguous
᎐
assignment of the M᎐N stretch. One might expect that the
᎐
nitridometal complex–Lewis acid interaction would weaken the
᎐
᎐
Re᎐N stretches in the IR spectra were assigned by analogy with
M᎐N bond, as is found to be the case with Lewis acid adducts
᎐
᎐
of oxometal complexes.13 However, in practice, an increase in
those of previously reported complexes.
᎐
Treatment of each of the transition-metal nitrido complexes
[Re(N)(PR3)(S2CNRЈ2)2] (PR3 = PMe2Ph, RЈ = Me; PR3 = PMe-
Ph2, RЈ = Et 1), [Re(N)(Cl)(PMePh2)2(S2CNMe2)] 2, [Mo(N)-
the M᎐N stretching frequency is usually observed, e.g. the
᎐
᎐
Re᎐N stretch in [AsPh ][Re(N)Br ] is observed to move from
᎐
4
4
1099 to 1170 cmϪ1 on addition of BBr3.14 This is often attrib-
(S2CNR2)3] (R = Me or Et) and [NBun ][Os(N)(1,2-S2C6H4)2]
᎐
uted to resonance between the B–N and M᎐N stretches;
4
᎐
with an excess of B(C6F5)3 in dichloromethane at ambient tem-
perature yields the nitridometal–Lewis acid adducts as purple
[Re{NB(C6F5)3}(PR3)(S2CNRЈ2)2] (PR3 = PMe2Ph, RЈ = Me
3; PR3 = PMePh2, RЈ = Et 4), orange [Re{NB(C6F5)3}(Cl)-
(PMePh2)2(S2CNMe2)] 5, cream and red-brown [Mo{NB-
however one of the referees has suggested an alternative
explanation based on Molecular Orbital theory. The “nitrogen
lone pair” MO in the parent nitrido compound has significant
M–N σ-antibonding character. Upon co-ordination of the
Lewis acid this orbital gains some B–N bonding character
hence increasing the M–N stretching frequency. In general, IR
stretching frequencies are more sensitive to such changes
(C6F5)3}(S2CNR2)3] (R = Me 6 or Et 7) and olive-green [NBun ]-
4
in antibonding/bonding character than are bond distances.
† During the revision of this manuscript a report of work demonstrat-
ing different reactivity between arylborane species and osmium nitrido
compounds was published.10
᎐
Tentative assignments of the M᎐N stretch in compounds 3 to 8,
᎐
based on the premise that they increase upon borane co-
J. Chem. Soc., Dalton Trans., 1998, 3941–3946
3941

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B(C6F5)3
N
Re
S
N
S
S
PR3
S
PR3
Re
S
i
R'2NC
R'2NC
S
S
S
CNR'2
CNR'2
PR3 = PMe2Ph, R' = Me;
PR3 = PMePh2, R' = Et 1
PR3 = PMe2Ph, R' = Me 3;
PR3 = PMePh2, R' = Et 4
B(C6F5)3
N
N
Ph2MeP
Ph2MeP
S
S
Ph2MeP
Ph2MeP
S
CNMe2
Re
Cl
CNMe2
Re
Cl
i
S
2
5
B(C6F5)3
N
N
S
S
CNR2
CNR2
S
S
Mo
S
S
S
S
Mo
S
i
R2NC
R2NC
S
S
S
CNR2
CNR2
R = Me 6, Et 7
B(C6F5)3
N
N
Os
i
[Bun4N]
S
S
[Bun4N]
S
S
Os
S
S
S
S
8
ii
B(C6F5)3
N
Me
S
S
Os
S
S
9
Scheme 1 Reagents and conditions: (i) excess of B(C6F5)3 in CH2Cl2; (ii) excess of MeO3CF3 in CH2Cl2.
ordination, are given in Table 1. The C6F5 regions of the
structurally characterised, however a single crystal X-ray study
has been performed on the closely related compound [Re(N)-
(PMe2Ph)(S2CNEt2)2].12 Comparison of the two structures
reveals the expected features, namely an extremely small
13C-{1H} and 19F NMR spectra of compounds 3 to 9 have been
15
assigned by analogy with those of B(C6F5)3 and also with
those of other published adducts.16 For compounds 3 to 5, the
phenyl resonances in the 13C-{1H} NMR spectra were assigned
increase in Re–N bond distance on Lewis acid co-ordination
n
᎐
by examination of the magnitude of JPC; for compound 4, a
[from 1.666(6) to 1.700(4) Å], an almost linear Re᎐N–B moiety
᎐
13C–1H correlation experiment was performed to assign the
downfield region of the 1H NMR spectrum. Other assignments
are straightforward and are not discussed further.
[170.9(3)Њ] and a significant diminishing of the trans influence
of the nitrido ligand (reduction in the difference between the
Re–Strans and Re–Scis distances from ca. 0.35 to ca. 0.25 Å).
Table 3 shows the structurally characterised borane adducts of
octahedral rhenium nitrido complexes found in the literature
and demonstrates the generality of all three of these features.
Crystallographically characterised starting metal nitrido com-
pounds are included for comparison purposes.
The molecular structure of compound 3 is shown in Fig. 1;
principal bond distances and angles are given in Table 2 . The
rhenium centre has an octahedral co-ordination environment
with the nitride–borane unit occupying an axial site and the
phosphine cis to it. The starting nitrido complex has not been
3942
J. Chem. Soc., Dalton Trans., 1998, 3941–3946

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Table 1 Analytical and spectroscopic data for compounds 1–9
Compounda
NMR Datab
1 [Re(N)(PMePh2)(S2CNEt2)2]
1H: 1.04 (dd, 6 H, 3JHH = 7.1, 7.2, NCH2CH3), 1.36 (dd, 6 H, 3JHH = 7.2, 7.2, NCH2CH3),
Orange-brown
2.31 (d, 3 H, 2JPH = 8.8, PCH3), 3.36, 3.58, 3.71 and 3.87 (m, 2 H each, NCH2CH3), 7.3–
7.8 (m, 10 H, PC6H5)
C, 40.2 (39.6); H, 4.7 (4.8); N, 5.8 (6.0); P, 4.6 (4.4)
IR: 1358s, 1302s, 1273s, 1212s, 1146s, 1096s, 1076s,
1054s [ν(Re–N)], 914s, 888s
13C-{1H}: 12.45 and 12.84 (s, NCH2CH3), 18.02 (d, 1JCP = 36.7, PCH3), 45.14 and 46.03 (s,
2
1
NCH2CH3), 128.38 (d, JCP = 11.2, PC6H5, Co), 131.56 (s, PC6H5, Cp), 134.04 (d, JCP
48.5, PC6H5, Cipso), 135.17 (d, 3JCP = 8.9, PC6H5, Cm), 202.66 and 223.87 (s, S2CNEt2)
31P-{1H}: Ϫ5.05 (s)
=
2 [Re(N)(Cl)(PMePh2)2(S2CNMe2)]
Yellow-brown
1H: 2.13 (d, 6 H, 2JPH = 8.9, PCH3), 3.24 (s, 6 H, NCH3), 7.1–7.7 (m, 20 H, PC6H5)
31P-{1H}: Ϫ10.77 (s)
C, 46.5 (46.1); H, 4.1 (4.3); N, 4.0 (3.7)
IR: 1261s, 1094s, 1060s [ν(Re–N)], 1020s, 800s
3 [Re{NB(C6F5)3}(PMe2Ph)(S2CNMe2)2]
Lavender
1H: 1.81 and 1.97 (d, 3 H each, 2JPH = 9.6, PCH3), 2.67, 2.98, 3.28 and 3.35 (s, 3 H each,
NCH3), 7.3–7.4 (m, 5 H, PC6H5)
C, 35.4 (35.2); H, 2.1 (2.1); B, 0.7 (1.0); N, 3.2 (3.85)
11B-{1H}: Ϫ3.9 (s)
Mass: 579, [M Ϫ B(C6F5)3]ϩ
13C-{1H}: 15.82 (d, JCP = 33.6, PCH3), 16.04 (d, JCP = 39.3, PCH3), 39.07,c 39.17 and
1
1
IR: 2727s, 1304s, 1281s, 1156s, 1092s [ν(Re–N)]d
39.71 (s, NCH3), 117.5 (br s, BC6F5, Cipso), 127.32 (d, JCP = 9.7, PC6H5, Co), 130.03 (s,
2
PC6H5, Cp), 131.37 (d, 3JCP = 8.3, PC6H5, Cm), 134.28 (d, 1JCP = 53.1, PC6H5, Cipso), 136.89
(d, 1JCF = 257, BC6F5, Cm), 139.42 (d, 1JCF = 247, BC6F5, Cp), 147.77 (d, 1JCF = 241, BC6F5,
Co), 201.75 and 228.20 (s, S2CNMe2)
31P-{1H}: Ϫ26.57 (s)
4 [Re{NB(C6F5)3}(PMePh2)(S2CNEt2)2]e
Purple
1H: 0.86 [d, 3 H, JHH = 6.5 (CH3)2CHOH], 0.94, 1.10, 1.25 and 1.37 (dd, 3 H each,
3
2
3JHH = 7.0, 7.0, NCH2CH3), 2.20 (d, 3 H, JPH = 9.0, PCH3), 3.22, 3.29, 3.42, 3.52, 3.59,
C, 41.3 (41.2); H, 3.05 (3.0); B, 0.85 (0.9); N, 3.4 (3.4);
P, 2.6 (2.5)
3.72, 3.78 and 3.81 (m, 1 H each, NCH2CH3), 3.73 [m, 0.5 H, (CH3)2CHOH], 7.22 (dd,
2 H, 3JPH = 8.5, 3JHH = 8.5, PC6H5, Ho), 7.29 (t, 1 H, 3JHH = 8.5, PC6H5, Hp), 7.36 (dd, 2 H,
3JHH = 8.5, 8.5, PC6H5, Hm), 7.42 (m, 2 H, PC6H5, Ho), 7.43 (m, 1 H, PC6H5, Hp), 7.65 (dd,
2 H, 3JHH = 8.5, 8.5, PC6H5, Hm)
Mass: 1209, Mϩ; 1042, [M Ϫ C6F5]ϩ; 842, [M Ϫ
PMePh2 Ϫ C6F5]ϩ; 697, [M Ϫ B(C6F5)3]ϩ; 581,
[M Ϫ B(C6F5)3 Ϫ 4Et]ϩ; 549, [M Ϫ B(C6F5)3 Ϫ S2-
CNEt2]ϩ; 497, [M Ϫ B(C6F5)3 Ϫ PMePh2]ϩ; 399,
[M Ϫ B(C6F5)3 Ϫ 2S2CNEt2]ϩ
11B-{1H}: Ϫ3.4 (s)
13C-{1H}: 1.10 [s, (CH3)2CHOH], 12.01, 12.43, 12.58 and 12.67 (s, NCH2CH3), 17.22, (d,
1JCP = 36.8, PCH3), 22.68 [s, (CH3)2CHOH], 44.72, 44.96, 45.00 and 45.98 (s, NCH2CH3),
119.0 (br s, BC6F5, Cipso), 128.02 and 128.38 (d, 2JCP = 11.0, PC6H5, Co), 130.23 and 130.93
IR: 1303m, 1276m, 1147m, 1089m [ν(Re–N)],d 978s
3
(s, PC6H5, Cp), 132.2 and 133.40 (d, JCP = 9.2, PC6H5, Cm), 133.7 and 136.88 (d,
1JCP = 49.2, PC6H5, Cipso), 136.81 (d, 1JCF = 271, BC6F5, Cm), 139.52 (d, 1JCF = 245, BC6F5,
Cp), 148.02 (d, 1JCF = 241, BC6F5, Co), 199.95 and 229.78 (s, S2CNEt2)
19F: Ϫ168.79 (dd, 6 F, 3JFF = 22.6, 20.7, BC6F5, Fm), Ϫ163.90 (t, 3 F, 3JFF = 20.7, BC6F5,
Fp), Ϫ133.80 (d, 6 F, 3JFF = 22.6, BC6F5, Fo)
31P-{1H}: Ϫ12.86 (s)
5 [Re{NB(C6F5)3}(Cl)(PMePh2)2(S2CNMe2)]
Orange
1H: 1.79 (d, 6 H, 2JPH = 9.5, PCH3), 3.16 (s, 6 H, NCH3), 7.0–7.8 (m, 20 H, PC6H5)
11B-{1H}: Ϫ2.7 (s)
1
1
C, 44.5 (44.5); H, 3.3 (2.5); N, 1.9 (2.2)
13C-{1H}: 15.31 (d, JCP = 36.6, PCH3), 19.17 (d, JCP = 38.3, PCH3), 38.58 and 39.65 (s,
IR: 1099w [ν(Re–N)],d 970w, 895m, 722m
NCH3), 120.1 (br s, BC6F5, Cipso), 127.84, 128.39, 129.01, 130.17, 130.92, 131.28, 132.18,
1
1
132.62 and 133.32 (PC6H5), 134.37 (d, JCP = 59.6, PC6H5, Cipso), 135.82 (d, JCP = 58.9,
PC6H5, Cipso), 136.68 (d, 1JCF = 252, BC6F5, Cm), 139.27 (d, 1JCF = 263, BC6F5, Cp), 148.03
(d, 1JCF = 253, BC6F5, Co), 191.15 (s, S2CNMe2)
31P-{1H}: Ϫ16.73 (s)
6 [Mo{NB(C6F5)3}(S2CNMe2)3]
Cream
1H: 3.19 (s, 3 H, NCH3), 3.25 (s, 6 H, NCH3), 3.34 (s, 6 H, NCH3), 3.38 (s, 3 H, NCH3)
11B-{1H}: Ϫ6.5 (s)
C, 33.6 (33.0); H, 1.9 (1.85); B, 1.0 (1.1); N, 4.9 (5.7)
Mass: 984, Mϩ; 773, [M Ϫ C6F5 Ϫ MNe2]ϩ; 697,
[M Ϫ C6F5 Ϫ S2CNMe2]ϩ; 472, [M Ϫ B(C6F5)3]ϩ;
352, [M Ϫ B(C6F3)3 Ϫ S2CNMe2]ϩ
IR: 1645w, 1559m, 1514m, 1305m, 1156m, 1082m
(br) [ν(Re–N)],d 979m (br)
13C-{1H}: 35.63, 37.36, 40.68 and 41.10 (s, NCH3),f 119.0 (br s, BC6F5, Cipso), 136.86 (d,
1JCF = 241, BC6F5, Cm), 139.28 (d, JCF = 247, BC6F5, Cp), 147.81 (d, JCF = 239, BC6F5,
1
1
Co), 200.78 and 203.62 (s, S2CNMe2)g
19F: Ϫ168.98 (m, 6 F, BC6F5, Fm), Ϫ163.87 (t, 3 F, 3JFF = 26.3, BC6F5, Fp), Ϫ134.17 (d, 6 F,
3JFF = 18.8, BC6F5, Fo)
7 [Mo{NB(C6F5)3}(S2CNEt2)3]
Red-brown
1H: 1.11–1.46 (m, 18 H, NCH2CH3), 3.61–3.81 (m, 12 H, NCH2CH3)
11B-{1H}: Ϫ6.6 (s)
C, 38.7 (37.2); H, 3.1 (2.8); B, 1.0 (1.0); N, 4.6 (5.25)
IR: 1302s, 1262s, 1209m, 1152m, 1089m [ν(Re–N)],d
976s
13C-{1H}: 11.77, 12.23, 12.36 and 12.48 (2, NCH2CH3),f 43.31, 44.46, 45.58 and 46.64 (s,
1
NCH2CH3),f 119.8 (br s, BC6F5, Cipso), 136.87 (d, JCF = 255, BC6F5, Cm), 139.24 (d,
1JCF = 248, BC6F5, Cp), 147.81 (d, 1JCF = 240, BC6F5, Co), 199.39 and 202.38 (s, S2CNEt2)g
1H: 0.90 [t, 12 H, 3JHH = 7.1, N(CH2)3CH3], 1.26 [m, 8 H, N(CH2)2CH2CH3], 1.37 (m, 8 H,
NCH2CH2CH2CH3), 2.63 [m, 8 H, NCH2(CH2)2CH3], 7.03 and 7.68 (m, AAЈBBЈ spin
system, 8 H, S2C6H4)
8 [NBun ][Os{NB(C6F5)3}(1,2-S2C6H4)2]
Olive-gr4een
C, 44.9 (44.6); H, 3.25 (3.6); B, 1.2 (0.9); N, 2.0 (2.3)
IR: 1644m, 1515s, 1283m, 1275m, 1097s, 979s, 794m
11B-{1H}: Ϫ3.7 (s)
13C-{1H}: 13.32 [s, N(CH2)3CH3], 19.72 [s, N(CH2)2CH2CH3], 23.68 (s, NCH2CH2-
CH2CH3), 58.98 [s, NCH2(CH2)2CH3], 114.0 (br s, BC6F5, Cipso), 124.69 and 127.90 (s,
1
1
S2C6H4), 136.67 (d, JCF = 238, BC6F5, Cm), 139.56 (d, JCF = 228, BC6F5, Cp), 147.56 (d,
1JCF = 246, BC6F5, Co), 149.77 (s, S2C6H4, Cipso
)
19F: Ϫ168.80 (m, 6 F, BC6F5, Fm), Ϫ162.99 (t, 3 F, 3JFF = 20.7, BC6F5, Fp), Ϫ134.72 (d, 6 F,
3JFF = 24.0, BC6F5, Fo)
9 [Os{NB(C6F5)3}{1,2-(S)(SMe)C6H4}(1,2-S2C6H4)]
1H: 3.06 (s, SCH3), 7.0–7.8 (br, C6H4)
Dark green oilh
11B-{1H}: Ϫ2.3 (s)
13C-{1H}: 33.5 (br s, SCH3), 118.7 (br s, BC6F5, Cipso), 122.17, 127.01, 128.36, 128.97,
130.47 and 132.27 [br s, S2C6H4 and (S)(SCH3)C6H4], 136.90, (d, 1JCF = 246, BC6F5, Cm),
140.30 (d, 1JCF = 267, BC6F5, Cp), 148.12 (d, 1JCF = 240, BC6F5, Co)
a Analytical data given as found (calculated) in %. Mass spectral data (Fast Atom Bombardment) given as m/z (assignment), selected IR data (cmϪ1
)
as Nujol mulls. b At probe temperature. Data given as: chemical shift (δ) (multiplicity, relative intensity, J in Hz, assignment). All obtained in CD2Cl2.
c Two coincident resonances. d Tentative assignment, see text. e Crystallised with 0.5 molecule of PriOH. f Resonances in 2:2:1:1 intensity ratio.
g Resonances in 2:1 intensity ratio. h Oil too sensitive to obtain microanalytical data.
J. Chem. Soc., Dalton Trans., 1998, 3941–3946
3943

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The NMR spectra of compounds 3–5 reveal that there is a
lowering of symmetry upon co-ordination of the Lewis acid.
For instance, compound 1 displays 2 methyl and 4 methylene
and THF and in all cases an excess of base was added to a
dichloromethane solution of the adduct and after 1 h stirring
the reaction residues were analysed by NMR spectroscopy.
Tetrahydrofuran was shown to cause no alteration to either the
1H or 11B-{1H} NMR spectra of all 3 compounds, however
NEt3 and PMe3 had differing effects depending on the metal
centre. For the rhenium complex 3 no effect was observed on
Lewis base addition, whereas for the osmium compound 8, add-
ition of L (L = PMe3 or NEt3) caused quantitative formation
of the parent nitrido compound and LؒB(C6F5)3 within 1 h. The
molybdenum compound 6 displayed intermediate stability
with approximately 50% displacement of the parent nitrido
complex by the competing Lewis base over 1 h. The difference
in stability of these 3 metal nitrido complex–Lewis acid adducts
1
resonances in its H NMR spectrum whereas 4 and 8 signals
respectively are observed for the B(C6F5)3 adduct 4. This may be
attributed to restriction of free rotation about the Re–P bond
upon addition of the bulky triarylborane. A further point of
interest is provided by compound 5 where there is apparently
only one dithiocarbamate methyl environment and one phos-
1
phine methyl environment in the H NMR spectrum but two
distinct resonances for each in the 13C-{1H} NMR spectrum.
This has been attributed to the different timescales involved in
1H and 13C-{1H} NMR spectroscopy. The adducts 6 and 7 dis-
play 4 distinct dithiocarbamate resonances in their 1H and
13C-{1H} NMR spectra with intensity ratios 1:2:2:1; this is in
agreement with published data for the compound [Mo(NCPh3)-
(S2CNMe2)3][BF4].8 The NMR spectra of compound 8 are
similar to those of the parent nitrido complex and are not
discussed further.
᎐
is probably due to steric factors since the Re᎐N–B moiety in 3 is
᎐
᎐
protected by the bulky cis tertiary phosphine and the Os᎐N–B
᎐
linkage in 8 is exposed by the ‘tied back’ dithiolate ligands.
Compound 6 displays intermediate steric hindrance.
Following the work of Sellmann et al.9 who demonstrated the
In order to test the strength of the M᎐N–B interaction, the
presence of two nucleophilic sites on the compound [NBun ]-
᎐
᎐
4
reactions of compounds 3, 6 and 8 with a series of competing
Lewis bases were attempted. The bases used were NEt3, PMe3
[Os(N)(1,2-S2C6H4)2], the B(C6F5)3 adduct of this metal nitrido
complex was treated with 2 competing Lewis acids, namely
[Ph3C][BF4] and MeO3SCF3. As expected, the bulky trityl
cation displaced the borane at the less hindered nitrido moiety
to yield the known compound [Os(NCPh3)(1,2-S2C6H4)2].9
However, reaction of [NBun ][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8
4
with an excess of methyl triflate in dichloromethane yields, after
extraction into toluene, the olive-green oil [Os{NB(C6F5)3}{1,2-
(S)(SMe)C6H4}(1,2-S2C6H4)] 9 in which Lewis acids are co-
ordinated to both nucleophilic sites. This adduct has been
characterised by NMR spectroscopy only since the oil was too
sensitive to obtain meaningful microanalytical data. This indi-
cates that the methyl group is relatively mobile and can move
between the 4 sulfur donors.
In conclusion, we have demonstrated that the nitrido group
in transition metal nitrido complexes is sufficiently nucleophilic
to form a dative bond with the Lewis acid B(C6F5)3. These
adducts are the first reported from direct reactions between a
triarylborane and a transition metal nitrido complex. The
᎐
M᎐N–B interaction is reasonably strong as demonstrated by
᎐
the relative stability of the adducts towards atmospheric oxygen
and moisture, although stability towards competing strong
Lewis bases seems to vary from metal to metal and is probably a
function of steric crowding.
Fig. 1 Molecular structure of [Re{NB(C6F5)3}(PMe2Ph)(S2CNMe2)2]
3 showing the atom numbering scheme. Hydrogen atoms are omitted
for clarity. Thermal ellipsoids are drawn at the 50% probability level.
Experimental
All preparations and manipulations of air and/or moisture
sensitive materials were carried out under an atmosphere of
dinitrogen using standard Schlenk line techniques or in an
inert-atmosphere glove-box containing dinitrogen. Dinitrogen
was purified before use by passage through a drying column
filled with activated molecular sieves (4 Å) and a deoxygenating
column filled with either manganese() oxide suspended on
vermiculite (Schlenk line) or BASF catalyst (glove-box). Sol-
vents were predried over activated 4 Å molecular sieves and
then distilled from sodium (toluene), sodium–potassium alloy
Table 2 Selected bond distances (Å) and angles (Њ) for compound 3
B(1)–N(3)
Re–N(3)
Re–S(1)
Re–S(2)
Re–S(3)
Re–S(4)
Re–P(1)
1.548(7)
1.700(4)
2.3769(12)
2.4350(15)
2.6090(12)
2.4608(13)
2.4154(15)
B(1)–N(3)–Re
170.9(3)
103.3(4)
114.5(4)
114.7(4)
109.0(4)
115.2(4)
100.4(4)
C(20)–B(1)–C(30)
C(30)–B(1)–C(40)
C(20)–B(1)–C(40)
C(20)–B(1)–N(3)
C(30)–B(1)–N(3)
C(40)–B(1)–N(3)
Table 3 Comparison of cis and trans metal–ligand distances and Re–N–B bond angles for some octahedral rhenium() nitrido complexes and their
Lewis acid adducts
Compound
Re–Ltrans/Å
Re–Lcis/Å
B–N–Re/Њ
Re–N/Å
3 [Re{NB(C6F5)3}(PMePh2)(S2CNMe2)2]
[Re(N)(PMe2Ph)(S2CNEt2)2]12
[Re(NBCl3)(PMe2Ph)(S2CNEt2)2]6
[Re(NBPh3)(PMe2Ph)(S2CNEt2)2]7
[Re(N)Cl2(PMe2Ph)3]17
2.6090
2.3769(12)–2.4608(13)
2.396(1)–2.449(1)
2.376(2)–2.455(2)
2.362(4)–2.431(4)
2.442(2)b
170.9(3)
a
170.5(3)
170.9(9)
a
1.700(4)
1.666(6)
1.704(3)
1.653(12)
1.660(8)
1.728(7)
2.793(2)
2.565(2)
2.579(4)
2.633(2)
2.439(3)
[Re(NBCl3)Cl2(PMe2Ph)3]18
2.394(3)b
176.5(6)
a Not applicable. b Re–Clcis distance.
3944
J. Chem. Soc., Dalton Trans., 1998, 3941–3946

View Article Online
[pentane and light petroleum (bp 40–60 ЊC)], potassium (THF)
or calcium hydride (dichloromethane) under a slow continuous
stream of dinitrogen. The Analar solvents methanol and PriOH
were used as supplied without drying and degassed by bubbling
dinitrogen through them for 15 min. Deuteriated dichloro-
methane for NMR spectroscopy was dried over calcium hydride
and deoxygenated by three freeze–pump–thaw cycles. Deuterio-
chloroform was used as supplied.
from yellow to violet was observed. After 1 h of stirring, light
petroleum (30 cm3) was added but no solid precipitated over-
night. Hence the volatiles were removed under vacuum and the
resulting oily solid triturated with light petroleum (20 cm3) to
yield the product as a lavender powder. Crystallisation by
slow evaporation of a solution of the product in PriOH and
dichloromethane (10 cm3 of a 1:1 mixture) led to its isolation
as purple single crystals which proved to be of insufficient
quality for analysis by X-ray diffraction. Microanalysis and
NMR spectroscopy identified this product as pure complex
4ؒ0.5 PriOH. Yield: 0.104 g (65%).
The NMR spectra were recorded on either a Varian Unity-
Plus 500 (1H, 11B, 13C, 19F and 31P at 499.87, 160.38, 123.70,
470.28 and 202.35 MHz respectively) or a Bruker AM300 spec-
trometer (1H, 11B, 13C and 31P at 300.13, 96.25, 75.5 and 121.6
MHz respectively). They were referenced internally using the
residual protio-solvent (1H) and solvent (13C) resonances and
measured relative to tetramethylsilane (δ 0), or referenced
externally to BF3ؒEt2O (11B, δ 0), CFCl3 (19F, δ 0) or 85% H3PO4
(31P, δ 0). Chemical shifts are quoted in δ (ppm); a positive sign
indicates a downfield shift relative to the standard. Fast atom
bombardment mass spectra were obtained by the EPSRC Mass
Spectrometry Service at the University College of Swansea
under the supervision of Dr J. A. Ballantine; infrared spectra as
Nujol mulls between NaCl plates on a Perkin-Elmer 1710 FTIR
spectrometer in the range 400 to 4000 cmϪ1. Elemental analyses
were obtained by the microanalytical department of the
Inorganic Chemistry Laboratory.
[Re{NB(C6F5)3}(Cl)(PMePh2)2(S2CNMe2)] 5. To a stirred
solution of [Re(N)(Cl)(PMePh2)2(S2CNMe2)] 2 (0.180 g, 0.238
mmol) in dichloromethane (15 cm3) a solution of B(C6F5)3
(0.144 g, 0.281 mmol) in dichloromethane (5 cm3) was added
dropwise. An immediate change from yellow to orange-red was
observed. Stirring was maintained for 3 h after which time the
solvent was removed under vacuum and the resulting red oily
solid triturated with pentane (20 cm3). This afforded the prod-
uct as a dark orange powder which was dried in vacuo overnight
and shown to be pure by microanalysis. Yield: 0.199 g (66%).
[Mo{NB(C6F5)3}(S2CNMe2)3] 6. To a stirred suspension of
[Mo(N)(S2CNMe2)3] (0.200 g, 0.425 mmol) in dichloromethane
(30 cm3) a solution of B(C6F5)3 (0.250 g, 0.488 mmol) in
dichloromethane (15 cm3) was slowly added. Stirring was main-
tained for 48 h after which time all solid material had dissolved
and the solution had changed from orange to red. Volatiles
were removed in vacuo to yield a brown oily solid which was
rendered as an orange powder by trituration with pentane (40
cm3). The yellow microcrystalline solid was obtained analytic-
ally pure by cooling a solution in dichloromethane (15 cm3) to
Ϫ80 ЊC. Yield: 0.251 g (60%).
The compounds [Re(N)Cl2(PMePh2)3],11 [Re(N)(PMe2Ph)-
(S2CNMe2)2],12 [Mo(N)(S2CNR2)3] (R = Me or Et),19 [N-
1,20
Bun ][Os(N)(1,2-S2C6H4)2]9 and B(C6F5)3
were prepared by
4
literature methods.
Preparations
[Re(N)(PMePh2)(S2CNEt2)2] 1. To a stirred solution of
[Re(N)Cl2(PMePh2)3] (0.300 g, 0.34 mmol) in methanol (30
cm3), NaS2CNEt2ؒ3H2O (0.233 g, 1.03 mmol) in methanol (15
cm3) was added. The reaction mixture, which immediately
changed from yellow to orange, was heated to reflux for 1 h
before being allowed to cool to room temperature. The solvent
was removed in vacuo and the resulting, rather oily, orange solid
washed with PriOH (20 cm3). Recrystallisation from PriOH and
dichloromethane (15 cm3 of a 1:1 mixture) at Ϫ80 ЊC afforded
complex 1 analytically pure. Yield: 0.116 g (48%).
[Mo{NB(C6F5)3}(S2CNEt2)3] 7. To a stirred suspension of
[Mo(N)(S2CNEt2)3] (0.250 g, 0.451 mmol) in dichloromethane
(30 cm3) a solution of B(C6F5)3 (0.245 g, 0.479 mmol) in
dichloromethane (15 cm3) was slowly added. Stirring was main-
tained for 48 h after which time all solid material had dissolved
and the solution had changed from brown to red. Volatiles were
removed in vacuo to yield a brown-red oil. This failed to crystal-
lise from a solution in dichloromethane–pentane (30 cm3 of a
1:4 mixture) and was rendered as a solid by sonication for 15
min in pentane (30 cm3). The red-brown foamy solid product
was isolated by filtration and dried overnight in vacuo. Yield:
0.101 g (21%).
[Re(N)(Cl)(PMePh2)2(S2CNMe2)] 2. The complex [Re(N)-
Cl2(PMePh2)3] (0.436 g, 0.500 mmol) was dissolved in methanol
(20 cm3) and a solution of NaS2CNMe2ؒH2O (72 mg, 0.500
mmol) in methanol (15 cm3) was added causing immediate
darkening of the reaction mixture. The mixture was heated to
reflux for 1 h after which time it was cooled to ambient tem-
perature and concentrated to half volume. This led to precipi-
tation of the product which was isolated analytically pure by
filtration and washing with PriOH (2 × 10 cm3). Yield: 0.201 g
(53%).
[NBun4][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8. To a stirred solution
of [NBun ][Os(N)(1,2-S2C6H4)2] (0.450 g, 0.619 mmol) in
4
dichloromethane (40 cm3), B(C6F5)3 (0.450 g, 0.879 mmol) in
dichloromethane (20 cm3) was added. An immediate change
from yellow to deep red was observed and after 1 h of stirring
the volatiles were removed under vacuum. The resulting oily
green solid was triturated with pentane (20 cm3) to yield the
product. It was isolated analytically pure as an olive-green
powder by filtration and drying under vacuum. Yield: 0.675 g
(88%).
[Re{NB(C6F5)3}(PMe2Ph)(S2CNMe2)2] 3. To a stirred solu-
tion of [Re(N)(PMe2Ph)(S2CNMe2)2] (0.289 g, 0.500 mmol) in
dichloromethane (20 cm3) was added B(C6F5)3 (0.280 g, 0.547
mmol) in dichloromethane (15 cm3). Upon stirring overnight
the solution darkened somewhat and the solvent was removed
under vacuum to yield a grey oily solid. The product was
afforded analytically pure by trituration with pentane (2 × 15
cm3) and drying overnight in vacuo. Single crystals suitable for
analysis by X-ray diffraction were grown by slow vapour dif-
fusion of pentane into a dichloromethane (20 cm3) solution of
complex 3 (ca. 20 mg). Yield: 0.300 g (55%).
[Os{NB(C6F5)3}{1,2-(S)(SMe)C6H4}(1,2-S2C6H4)] 9. The
complex [NBun ][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8 (200 mg,
4
0.160 mmol) and MeO3SCF3 (50 mg, 0.305 mmol) were com-
bined in a dry-box and dissolved in dichloromethane (15 cm3).
The reaction mixture was stirred for 1 h without any obvious
colour change and then the volatiles were removed under
vacuum. Extraction of the oily residues with toluene yielded a
red solution. Removal of the solvent from this afforded the
product as an olive-green oil. Vigorous washing with pentane
(30 cm3) failed to yield a solid so the product was characterised
[Re{NB(C6F5)3}(PMePh2)(S2CNEt2)2] 4. To a stirred solution
of [Re(N)(PMePh2)(S2CNEt2)2] 1 (90 mg, 0.129 mmol) in
dichloromethane (15 cm3), B(C6F5)3 (72 mg, 0.140 mmol) in
dichloromethane (5 cm3) was added. An immediate change
J. Chem. Soc., Dalton Trans., 1998, 3941–3946
3945

View Article Online
by NMR spectroscopy. It was too air-sensitive to allow satisfac-
tory microanalytical data to be obtained.
11663 Reflections were measured (1 < θ < 26Њ, h, k, ϩl, 6103
unique giving 5408 with I > 3σ(I). The images were processed
with the DENZO and SCALEPACK programs.21
Reactions with L ؍ THF, NEt3 or PMe3
Structure solution and refinement. All solution, refine-
ment and graphical calculations were performed using the
CRYSTALS22 and CAMERON23 software packages. The
structure was solved by direct methods using the SIR 92 pro-
gram24 and refined by a full-matrix least squares procedure on
F. All non-hydrogen atoms were refined with anisotropic dis-
placement parameters. All hydrogen atoms were generated and
allowed to ride on their corresponding carbon atoms with fixed
thermal parameters. A Chebychev weighting scheme with the
parameters 2.84, 0.362 and 2.06 was applied as well as an
empirical absorption correction.25 This yielded R = 0.042 and
RЈ = 0.051 with maximum residual electron density of 1.61 e
[Re{NB(C6F5)3}(PMe2Ph)(S2CNMe2)2] 3. To a solution of
[Re{NB(C6F5)3}(PMe2Ph)(S2CNMe2)2] 3 (20 mg, 0.018 mmol)
in dichloromethane (10 cm3) was added an excess of Lewis
base; either THF (3 drops), NEt3 (3 drops) or PMe3 (1 cm3 of a
0.105 M solution in light petroleum, 0.105 mmol). No immedi-
ate colour change was observed and the reactions were allowed
to proceed for 1 h. Volatiles were then removed in vacuo and the
1
residues dried for 2 h. The products were analysed by H and
11B-{1H} NMR spectroscopy in CDCl3 and this showed that in
all three experiments no reaction of compound 3 had occurred.
[Mo{NB(C6F5)3}(S2CNMe2)3] 6. To a solution of [Mo{NB-
(C6F5)3}(S2CNMe2)3] 6 (20 mg, 0.020 mmol) in dichloro-
methane (10 cm3) an excess of Lewis base was added as above.
Little immediate colour change was observed and the reactions
were allowed to proceed for 1 h. Further treatment and NMR
analysis as above showed that in the case where L = THF no
decomposition of compound 6 had occurred whereas when
L = NEt3 or PMe3 the residue consisted of ca. 50% 6 and 50%
[Mo(N)(S2CNMe2)3] plus B(C6F5)3ؒL. NMR data (CDCl3, 298
K): B(C6F5)3ؒNEt3, 1H, δ 1.46 (m, 9 H, NCH2CH3) and 3.60 (m,
6 H, NCH2CH3); 11B-{1H}, δ Ϫ4.2 (s); B(C6F5)3ؒPMe3, 1H,
δ 1.79 (d, 2JPH = 13.1 Hz, PCH3); 11B-{1H}, δ Ϫ4.4 (s)
ÅϪ3
.
CCDC reference number 186/1188.
See http://www.rsc.org/suppdata/dt/1998/3941/ for crystallo-
graphic files in .cif format.
Acknowledgements
We thank St John’s College for a Junior Research Fellowship
(to L. H. D.) and the EPSRC for support of this work.
References
1 A. N. Chernega, A. J. Graham, M. L. H. Green, J. Haggitt, J. Lloyd,
C. P. Mehnert, N. Metzler and J. Souter, J. Chem. Soc., Dalton
Trans., 1997, 2293.
2 J. R. Galsworthy, M. L. H. Green, N. Maxted and M. Müller,
J. Chem. Soc., Dalton Trans., 1998, 387.
3 J. R. Galsworthy, M. L. H. Green, M. Müller and K. Prout, J. Chem.
Soc., Dalton Trans., 1997, 1309.
4 J. R. Galsworthy, J. C. Green, M. L. H. Green and M. Müller,
J. Chem. Soc., Dalton Trans., 1998, 15.
5 J. Chatt and B. T. Heaton, J. Chem. Soc. A, 1971, 705.
6 S. Ritter and U. Abram, Z. Anorg. Allg. Chem., 1996, 622, 965.
7 S. Ritter and U. Abram, Inorg. Chim. Acta, 1995, 231, 245.
8 M. W. Bishop, J. Chatt, J. R. Dilworth, B. D. Neaves, P. Dahlstrom,
J. Hyde and J. Zubieta, J. Organomet. Chem., 1981, 213, 109.
9 D. Sellmann, M. W. Wemple, W. Donaubauer and F. W. Heinemann,
Inorg. Chem., 1997, 36, 1397.
[NBun ][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8. To a solution of
4
[NBun ][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8 (20 mg, 0.016 mmol) in
4
dichloromethane (10 cm3) an excess of Lewis base was added as
above. Little immediate colour change was observed and the
reactions were allowed to proceed for 1 h. Further treatment
and NMR analysis as above showed that in the case where
L = THF no decomposition of compound 8 had occurred
whereas when L = NEt3 or PMe3 the residue consisted entirely
of [NBun ][Os(N)(1,2-S2C6H4)2]9 and B(C6F5)3ؒL (NMR spec-
4
troscopic data as above).
Reaction of [NBun4][Os{NB(C6F5)3}(1,2-S2C6H4)2] 8 with
[Ph3C][BF4]
10 T. J. Crevier and J. M. Mayer, Angew. Chem., Int. Ed. Engl., 1998,
37, 1891.
11 J. Chatt, J. D. Garforth, N. P. Johnson and G. A. Rowe, J. Chem.
Soc., 1964, 1012.
12 S. Ritter and U. Abram, Z. Anorg. Allg. Chem., 1994, 620, 1443.
13 C.-H. Yang, J. A. Ladd and V. L. Goedken, J. Coord. Chem., 1988,
18, 317.
14 W. Kafitz, F. Weller and K. Dehnicke, Z. Anorg Allg. Chem., 1982,
490, 175.
15 A. G. Massey and A. J. Park, J. Organomet. Chem., 1966, 5, 218.
16 J. Karl, G. Erker and R. Fröhlich, J. Am. Chem. Soc., 1997, 119,
11165.
17 E. Forsellani, U. Casellato, R. Graziani and L. Magon, Acta
Crystallogr., Sect. B, 1982, 38, 3081.
18 R. Dantona, E. Schweda and J. Strähle, Z. Naturforsch., Teil B, 1984,
39, 733.
Complex 8 (50 mg, 0.040 mmol) and [Ph3C][BF4] (50 mg, 0.151
mmol) were combined as solids and dissolved in dichlorometh-
ane (15 cm3). The mixture was stirred for 30 min after which it
appeared to have darkened slightly. The volatiles were removed
in vacuo and the whole of the reaction residues analysed by 1H,
11B-{1H} and 13C-{1H} NMR spectroscopy in CDCl3. This
confirmed the formation of the known compound [Os(NCPh3)-
(1,2-S2C6H4)2],9 B(C6F5)3 and [NBun ][BF4].
4
Crystallography
Single crystals of complex 3 suitable for analysis by X-ray
crystallography were grown by slow vapour diffusion of
pentane into a solution of 3 in dichloromethane at 298 K. A
plate-shaped crystal was selected for diffraction, covered with
paratone-N oil under an inert atmosphere and mounted on the
end of a glass fibre.
19 J. Chatt and J. R. Dilworth, J. Indian Chem. Soc., 1977, 54, 13.
20 A. G. Massey and A. J. Park, J. Organomet. Chem., 1964, 2, 245.
21 Z. Otwinowski and W. Minor, Methods Enzymol., 1996, 276, 307.
22 D. J. Watkin, C. K. Prout, J. R. Carruthers and P. W. Betteridge,
CRYSTALS User Guide, Issue 10, Chemical Crystallography
Laboratory, University of Oxford, 1996.
Crystal data. C32H23BF15N3PReS4 3, M = 1090.75, triclinic,
¯
23 D. J. Watkin, C. K. Prout and L. J. Pearce, CAMERON, Chemical
Crystallography Laboratory, University of Oxford, 1996.
24 A. Altomare, G. Cascarano, G. Giacovazzo, A. Guagliardi, M. C.
Burla, G. Polidori and M. Camalli, SIR 92, Program for auto-
matic solution of crystal structures by direct methods, J. Appl.
Crystallogr., 1994, 27, 435.
space group P1, a = 8.871(5), b = 13.233(1), c = 16.7220(13) Å,
α = 80.73(4), β = 77.13(5), γ = 86.05(5)Њ, V = 1887.6 Å3, Z = 2,
Dc = 1.92 g cmϪ3, µ = 3.62 mmϪ1, purple crystals, crystal
dimensions 0.25 × 0.05 × 0.05 mm.
Data collection and processing. Data were collected at 125 K
on an Enraf-Nonius DIP2000 image plate diffractometer with
graphite monochromated Mo-Kα radiation (λ = 0.71069 Å).
25 N. Walker and D. Stuart, Acta Crystallogr., Sect. A, 1983, 39, 158.
Paper 8/05425H
3946
J. Chem. Soc., Dalton Trans., 1998, 3941–3946