From straight chain to macrocyclic complexes containing mixed sulfur/nitrogen donors and coordinated 1,3-diynes

Article abstract of DOI:10.1016/j.jorganchem.2007.07.015

The acid-mediated reaction of [{Co₂(CO)₆(μ-η²-HOCH₂C{triple bond, long}C-)}₂] (1) with the meta- and para-substituted aminothiophenols, 3-NH₂-C₆H₄SH and 4-NH₂

Full text of DOI:10.1016/j.jorganchem.2007.07.015

Journal of Organometallic Chemistry 692 (2007) 4985–4994
www.elsevier.com/locate/jorganchem
From straight chain to macrocyclic complexes containing mixed
sulfur/nitrogen donors and coordinated 1,3-diynes
a,b,
a
c,
*
Vladimir B. Golovko
*, Martin J. Mays , Gregory A. Solan
a
Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
Department of Chemistry, Canterbury University, Private Bag 4800, Christchurch, New Zealand
b
c
Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
Received 20 June 2007; received in revised form 11 July 2007; accepted 12 July 2007
Available online 19 July 2007
Abstract
The acid-mediated reaction of [{Co2(CO)6(l-g2-HOCH2C„C–)}2] (1) with the meta- and para-substituted aminothiophenols,
3-NH2–C6H4SH and 4-NH2–C6H4SH, affords the straight chain species, [{Co2(CO)6(l-g2-(3-NH2–C6H4S)CH2C„C–)}2] (2) and
[{Co2(CO)6(l-g2-(4-NH2–C6H4S)CH2C„C–)}2] (3), respectively. The molecular structure of 3 reveals the presence of two isomeric
forms differing in the relative disposition of the S-aryl groups. Conversely, reaction of 1 with the ortho-substituted aminothiophenol,
2-NH2–C6H4SH, furnishes the 10-membered macrocyclic species [{Co2(CO)6}2{cyclo-l-g2:l-g2-CH2C2C2CH2SC6H3–NH-2}] (4) along
with the linear chain complex [{Co2(CO)6(l-g2-(2-NH2–C6H4S)CH2C„C–)}2] (5). On the other hand, treatment of 1 with the ortho-
substituted mercaptopyridine, 2-SH–C5H4N, in the presence of HBF4 gives the salt [{Co2(CO)6(l-g2-(2-S–C5H4NH)CH2C„C–)}2]-
(BF4)2 (6a) in good yield; work-up in the presence of base affords the neutral complex [{Co2(CO)6(l-g2-(2-S–C5H4N)CH2C„C–)}2]
(6b). Single crystal X-ray diffraction studies have been reported on 3–5 and 6a.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Cobalt; Coordinated 1,3-diyne; Macrocycle; Straight chain; N–C bond formation; Nicholas reaction
1. Introduction
Recently, we have been interested in employing the con-
jugated 1,3-diynediol, [{Co2(CO)6(l-g2-HOCH2C„C–)}2]
(1, Fig. 1), as a substrate in Nicholas chemistry and have
demonstrated that substituted aromatics can act as com-
patible reaction partners for facilitating ring formation.
Depending on the nature of the aromatic substitution pat-
tern, ring closure by a dual S,S- [10], C,C- [11], C,O- [11] or
S,C-centred [12] nucleophilic attack are all possible leading
to macrocycles (or carbocycles) with ring sizes between
eight and twenty-two atoms.
As an extension to this work, this note is concerned with
targeting aromatic reagents that could facilitate S,N-cen-
tred ring closure. Specifically, the acid-mediated reaction
of 1 with 2-, 3- and 4-aminothiophenols along with 2-mer-
captopyridine is probed in this study. It is noteworthy that
studies concerned with N–C coupling reactions employing
primary amines in Nicholas chemistry remain, in their own
right, scarce [13].
The application of Nicholas-type chemistry [1] to pro-
mote the formation of ring systems containing both alky-
nes and a variety of other donor units has been the
subject of a number of studies [2–4]. In particular,
butyne-1,4-diol-Co2(CO)6 complexes and its derivatives
have served as highly effective precursors to cyclic assem-
blies [3,4], while the use of more extended substrates such
as bis(propargyl alcohol)–Co4(CO)12 complexes has only
in recent years come to the fore [5–7]. This has, in part,
been stimulated by the relevance of the resulting materials
to nanoscience [8], molecular sensors [9] and to natural
products [2,5].
*
Corresponding authors. Tel.: +44 0116 252 2096; fax: +44 0116 252
3789.
E-mail address: gas8@leicester.ac.uk (G.A. Solan).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.07.015

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V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
„C–)}2] (3) in moderate to high yield, respectively. Use of
OH
HO
H
H
H
H
an equimolar ratio of the reagents also gave 2 and 3 but in
lower yields. Complexes 2 and 3 have been characterised
by mass spectrometry and by 1H and 13C NMR and IR spec-
troscopy (see Table 1 and Section 4). In addition, complex 3
has been the subject of a single crystal X-ray diffraction
study.
(OC)6Co2
Co2(CO)6
Fig. 1. Bis(Co2(CO)6)-coordinated diyne-diol 1.
Suitable crystals of 3 for the X-ray determination were
grown from dichloromethane by slow diffusion of hexane
at 0 ꢁC. The molecular structure reveals that 3 exists as
two geometric isomers (molecules A and B) one of which
(B) contains a crystallographic centre of symmetry. Per-
spective views of molecule A (cis-aryls) and B (trans-aryls)
are shown in Fig. 2a and 2b; selected bond lengths and
angles for both molecules are listed in Table 2. Both iso-
mers of 3 consist of a (4-NH2–C6H4)SCH2C„CC„C
2. Results and discussion
Reaction of [{Co2(CO)6(l-g2-HOCH2C„C–)}2] (1) [14]
with slightly greater than 2 equiv of x-NH2–C6H4SH
(x = 3, 4) in the presence of an excess of HBF4 Æ OEt2 affor-
ded, on work-up, [{Co2(CO)6(l-g2-(3-NH2–C6H4S)CH2C
„C–)}2] (2) and [{Co2(CO)6(l-g2-(4-NH2–C6H4S)CH2C
Table 1
Selected characterisation data for the new complexes 2–6
Complex
v(CO)a (cmꢀ1
)
1H NMRb (d)
LSI mass spectrum
2
2101(s), 2082(s),
2060(vs), 2027(s)
2100(m), 2082(vs),
2060(vs), 2031(vs)
2100(s), 2081(vs),
2059(vs), 2026(vs)
7.11 (m, 2H, C6H4), 6.81 (m, 2H, C6H4), 6.74 (m, 2H, C6H4),
6.55 (m, 2H, C6H4), 4.48 (s, 4H, CH2S), 3.69 (s, 4H, NH2)
M+ꢀnCO (n = 2–4, 6–12)
M+ꢀnCO (n = 1–12)
2
2
3
4
7.30 (d, 4H, C6H4, JHꢀH 8.4), 6.63 (d, 4H, C6H4, JHꢀH 8.4),
4.34 (s, 4H, CH2S), 3.71 (s, 4H, NH2)
7.59 (d, 1H, C6H4, 2JHꢀH 7), 7.33 (t, 1H, C6H4, 2JHꢀH 7.0), 7.11 (d, 1H, C6H4, M++H (772), M+ꢀnCO
2
2
2JHꢀH 8.0), 6.79 (t, 1H, C6H4, JHꢀH 7.0), 5.81 (t, 1H, NH, JHꢀH 7.0), 4.99
(n = 1–12)
2
(d, 2H, CH2NH, JHꢀH 7.0), 4.27 (s, 2H, CH2S)
2
3
2
5
2101(s), 2082(vs),
2060(vs), 2033(s),
2026(s)
2099(w), 2080(s),
2058(vs), 2024(s)
7.45 (dd, 2H, C6H4, JHꢀH 7.7, JHꢀH 1.5), 7.14 (dt, 2H, C6H4, JHꢀH 8.0,
M++H (897), M+ꢀnCO
(n = 3–12)
3JHꢀH 1.5), 6.74 (dd, 2H, C6H4, JHꢀH 8.0, 3J
1.2), 6.71 (dt, 2H, C6H4,
2
HꢀH
3
2J
7.7, JHꢀH 1.2), 4.35 (s, 4H, NH2), 4.29 (s, 4H, CH2S)
HꢀH
6a
11.0 (s, br, 2H, C5H4NH), 8.41–8.40 (m, 2H, C5H4NH), 7.56–7.54 (m, 2H,
C5H4NH), 7.27–7.24 (m, 2H, C5H4NH), 7.00–6.98 (m, 2H, C5H4NH),
4.91 (s, 4H, CH2)
8.41–8.40 (m, 2H, C5H4N), 7.50–7.48 (m, 2H, C5H4N), 7.21–7.20
(m, 1H, C5H4N), 7.00 (m, 2H, C5H4N), 4.83 (s, 4H, CH2)
M+–BF4 (957), M+–2BF4
(868), M+ꢀnCO (n = 3–12)
6b
2099(w), 2080(s),
2058(vs), 2024(s)
M++Na (892), M+ (868),
M+ꢀnCO (n = 3–12)
a
Recorded in CH2Cl2 (apart from 6a in THF) in 0.5 mm NaCl solution cells.
1H NMR chemical shifts in ppm relative to SiMe4 (0.0 ppm), coupling constants in Hz in CDCl3 at 293 K.
b
Fig. 2a. Molecular structure of 3 (molecule A: cis-aryls) with partial atom labeling scheme; all hydrogen atoms, apart from the amino hydrogens, have
been omitted for clarity.

V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
4987
Fig. 2b. Molecular structure of 3 (molecule B: trans-aryls) with partial atom labeling scheme; all hydrogen atoms apart from the amino hydrogens, have
been omitted for clarity.
CH2S (C6H4-4-NH2) chain in which the alkynic moieties
are each coordinated by a Co2(CO)6 unit in an g2:g2 fash-
ion with the relative disposition of aryl groups defining the
isomeric description (viz. cis/trans aryls). The Co2C2 cores
adopt the expected tetrahedral arrangements with the
Co–Co and C(alkyne)–C(alkyne) bond distances falling
within the normal ranges [15–17]. The two Co2C2 units in
each isomer are disposed mutually trans [tors.: C(14)–
C(15)–C(16)–C(17) 180.0ꢁ (molecule A) C(14)–C(15)–
C(15A)–C(14A) 180.0ꢁ; (molecule B)], a configuration that
is observed in the majority of crystallographically charac-
terised neutral acyclic 1,3-diyne complexes [16]; complex
1 being an exception [14c]. The C„C–CH2 bend-back
angles [C(13)–C(14)–C(15) 140.8(8)ꢁ, C(18)–C(17)–C(16)
140.8 (8)ꢁ (molecule A); C(13)–C(14)–C(15) 138.8(2)ꢁ (mol-
ecule B)] are slightly lower than those found in related acy-
clic cobalt–alkyne complexes; the mean C„C–CH2 angle is
141.31ꢁ [18]. Some evidence for delocalisation is apparent
˚
in the C(15)–C(16) [1.407(11) A] and C(15)–C(15A)
˚
[1.424(16) A] bonds of both molecules, a feature that has
also been observed in other bis(Co2(CO)6)-coordinated
1,3-diyne complexes [16,17]. Each cobalt atom is coordi-
nated by three carbonyl ligands which display the expected
linear geometries. Some differences are apparent at the
propargylic carbon atoms between isomers with the
C(14)–C(13)–S(1) angle in molecule A being notably
Table 2
˚
Selected bond distances (A) and angles (ꢁ) for 3
Molecule A
Molecule B
Bond lengths
C(22)–N(1)
C(19)–S(1)
1.400(13)
1.781(1)
C(22)–N(1)
C(19)–S(1)
1.402(14)
1.766(9)
C(13)–S(1)
1.819(9)
C(13)–S(1)
1.811(9)
C(13)–C(14)
C(14)–C(15)
Co(1)–Co(2)
Co–C (carbonyl)
C–O (carbonyl)
Co–C (alkyne)
C(15)–C(16)
C(16)–C(17)
C(17)–C(18)
C(18)–S(2)
1.470(12)
1.362(12)
C(13)–C(14)
C(14)–C(15)
Co(1)–Co(2)
Co–C (carbonyl)
C–O (carbonyl)
Co–C (alkyne)
C(15)–C(15A)
1.501(13)
1.346(12)
2.4706(18)
1.794(12)–1.842(11)
1.103(13)–1.156(13)
1.944(9)–1.972(9)
1.424(16)
2.4781(16)
1.785(10)–1.860(12)
1.114(12)–1.136(11)
1.950(8)–1.978(7)
1.407(11)
1.357(12)
1.482(12)
1.807(9)
S(2)–C(25)
1.770(9)
C(28)–N(2)
Co(3)–Co(4)
1.399(14)
2.4788(16)
Bond angles
C(19)–S(1)–C(13)
S(1)–C(13)–C(14)
C(13)–C(14)–C(15)
C(14)–C(15)–C(16)
C(15)–C(16)–C(17)
C(16)–C(17)–C(18)
C(17)–C(18)–S(2)
C(18)–S(2)–C(25)
103.5(4)
C(19)–S(1)–C(13)
S(1)–C(13)–C(14)
C(13)–C(14)–C(15)
C(14)–C(15)–C(15A)
105.0(4)
113.3(6)
140.8(8)
143.7(8)
147.0(8)
140.0(8)
117.0(6)
104.9(4)
117.0(6)
138.8(8)
146.2(11)
Atoms with suffix A are generated by symmetry (1 ꢀ x + 1, ꢀy + 1, ꢀz + 2).

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V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
Co2(CO)6
(4-NH2-C6H4)S
S(C6H4-4-NH2)
Co2(CO)6
3
(ii)
NH
S
Co2(CO)6
HO
OH
(iii)
(OC)6Co2
(i)
Co2(CO)6
(3-NH2-C6H4)S
S(C6H4-3-NH2)
4
Co2(CO)6
Co2(CO)6
(OC)6Co2
1
2
Co2(CO)6
(2-NH2-C6H4)S
(iv)
S(C6H4-2-NH2)
Co2(CO)6
(BF4)2
5
NH
S
NH
S
(OC)6Co2
Co2(CO)6
6a
Scheme 1. Reagents and conditions: (i) 3-NH2C6H4SH, xs. HBF4 Æ OEt2, ꢀ78 ꢁC, CH2Cl2; (ii) 4-NH2C6H4SH, xs. HBF4.OEt2, ꢀ78 ꢁC, CH2Cl2; (iii) 2-
NH2C6H4SH, xs. HBF4.OEt2, ꢀ78 ꢁC, CH2Cl2; (iv) 2-HSC5H4N, HBF4.OEt2, ꢀ78 ꢁC, CH2Cl2.
smaller [113.3(6)ꢁ] than the corresponding angle [117.0(6)ꢁ]
in the molecule B. Inspection of the packing picture reveals
no significant intermolecular contacts.
structure of 4 is shown in Fig. 3; selected bond lengths and
angles are collected in Table 3. The structure consists of a
10-membered S–C–C„C–C„C–C–N–C@C– ring in
which the two alkyne moieties are perpendicularly bound
by two Co2(CO)6 units. The bond parameters within the
Co2C2 cores fall in the normal ranges [15–17] with the rela-
tive disposition of the cores being best described as pseudo
cis [tors. C(14)–C(15)–C(16)–C(17) 42.7ꢁ]. The bend-back
angles are inequivalent with the C(13)–C(14)–C(15)
The IR spectra of 2 and 3 are almost identical, with
four bands in the m(CO) region in a pattern similar to
that seen in related non-cyclic bis(dicobalt hexacar-
bonyl)-coordinated diyne complexes [15,16]. The LSI
mass spectra display fragmentation peaks corresponding
to the loss of carbonyl groups from the proposed molec-
ular ions while the electrospray mass spectrum of 2
shows a peak for the protonated form of the molecular
1
ion. The H and 13C NMR spectra give the expected dis-
tribution of signals with the equivalent propargyl carbon
atoms and the proparylic hydrogens in 2 and 3 seen as
singlets in both the 13C NMR and 1H NMR spectra,
respectively.
Reaction of 1 with slightly greater than 2 equiv of 2-ami-
nothiophenol in the presence of an excess of HBF4 Æ OEt2
in dichloromethane at ꢀ78 ꢁC gave [{Co2(CO)6}2{cyclo-
l-g2:l- g2- CH2C2C2CH2SC6H3–NH-2}] (4) and [{Co2(CO)6-
(l-g2-(2-NH2–C6H4S)CH2C„C–)}2] (5) in a 7:10 ratio
(Scheme 1). Complex 5 could be formed as the unique
product when a large excess of 2-aminothiophenol was
employed. Complexes 4 and 5 have been characterised by
1
LSI mass spectrometry and by H and 13C NMR and IR
spectroscopy (see Table 1 and Section 4). In addition, both
complexes have been the subject of single crystal X-ray dif-
fraction studies.
Crystals of complex 4 and 5 suitable for the single
crystal X-ray diffraction studies were grown from dichloro-
methane at 0 ꢁC by slow diffusion of hexane. The molecular
Fig. 3. Molecular structure of 4 with partial atom labeling scheme; all
hydrogen atoms have been omitted for clarity.

V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
4989
Table 3
Selected bond distances and angles for 4
˚
Bond lengths (A)
N(1)–C(13)
C(13)–C(14)
C(14)–C(15)
C(15)–C(16)
C(16)–C(17)
C(17)–C(18)
C(18)–S(2)
S(2)–C(19)
1.455(4)
1.501(4)
1.351(3)
1.436(4)
1.355(4)
1.481(4)
1.834(3)
1.778(3)
C(19)–C(24)
C(24)–N(1)
1.411(4)
1.387(4)
2.4647(6)
2.4630(6)
1.786(3)–1.839(3)
1.122(4)–1.137(4)
1.953(3)–1.990(3)
Co(1)–Co(2)
Co(3)–Co(4)
Co–C (carbonyl)
C–O (carbonyl)
Co–C (alkyne)
Bond angles (ꢁ)
N(1)–C(13)–C(14)
C(13)–C(14)–C(15)
C(14)–C(15)–C(16)
C(15)–C(16)–C(17)
C(16)–C(17)–C(18)
113.0(2)
C(17)–C(18)–S(2)
C(18)–S(2)–C(19)
S(2)–C(19)–C(24)
C(19)–C(24)–N(1)
115.4(2)
140.1(3)
142.5(3)
143.1(3)
145.7(3)
101.56(14)
120.3(3)
120.3(3)
angle being significantly less (by 5.6ꢁ) than the C(16)–
C(17)–C(18) angle. It is tempting to ascribe this difference
to the presence of the nitrogen and sulfur atoms that are
linked to C(13) and C(18), respectively. However, inspec-
tion of the corresponding angles in the related complex
[{Co2(CO)6}2(l-g2:l-g2-cyclo-1,2-S–C6H4–SCH2C„CC-
CCH2)], in which the N(1) atom in 4 is replaced by a sulfur
atom, reveals a similar asymmetry, albeit less significant
(3.6ꢁ variation) [10]. The torsion angles of 67.8ꢁ and
94.1ꢁ for C(24)–N(1)–C(13)–C(14) and C(19)–S(2)–C(18)–
C(17) indicate significant deviations from the preferred
gauche arrangements [19] of C–E–C–C (E = heteroatom)
bonds which is likely enforced by the rigid 1,2-C6H4 linker.
No significant intermolecular interactions are apparent.
The molecular structure of 5 is shown in Fig. 4; selected
bond lengths and angles are presented in Table 4. The
molecular structure contains a crystallographic centre of
symmetry which lies at the midpoint of the C(7)–C(7A)
bond. The structure of 5 resembles 3 (molecule B: trans-
aryls) with a bis(Co2(CO)6)-coordinated hexa-2,4-diyne
chain in this case end-capped by two S(2-NH2–C6H4)
groups. As with both isomers of 3, the Co2C2 cores in 5
C(8)–C(7)–C(7A)–C(8A) 180ꢁ]. The geometric features
within each Co2C2 core are unexceptional while the bend-
back angle [C(9)–C(8)–C(7) 136.4(3)ꢁ] is lower than in 3.
The pattern of terminal carbonyl bands in IR spectra of
4 and 5 is similar to that seen for 2 and 3 and indeed is typ-
ical of other bis(dicobalt hexacarbonyl)-coordinated diyne
1
complexes [15,16]. In the H NMR spectrum of 4, there
are two propargyl CH2 signals at d 5.00 (CH2NH) and
4.27 (CH2S) whereas in 5 the equivalent CH2 signals are
seen as singlet at d 4.29. Furthermore, the NH–CH2 con-
nectivity in 4 is confirmed by a three-bond coupling
(3JHH 7 Hz) between the corresponding protons. The 13C
NMR spectra supports the unsymmetrical nature of com-
plex 4 with four alkynic carbon signals (d 101.6, 97.2,
93.8 and 92.8) and two methylene carbon signals (d 49.3,
45.3). Molecular ion peaks in the LSI mass spectra are seen
for both 4 and 5 along with fragmentation peaks corre-
sponding to the loss of carbonyl groups.
Higher yields of 4 could be achieved by treating 1 with
firstly HBF4 Æ OEt2 to generate the dication [{Co2(CO)6}2
{l-g2:l-g2-(CH2C„C)2}](BF4)2 [14c,20] and then with
2-aminothiophenol to afford 4 as the sole product. It would
therefore seem likely that the protic media involved in these
Nicholas-type reactions inhibits N-alkylation of the pri-
mary amine in 2-aminothiophenol (or an intermediate).
Indeed, it has been previously suggested that the propargy-
are also configured in
a
trans-disposition [tors:
Table 4
Selected bond distances and angles for 5
˚
Bond lengths (A)
C(10)–S(1)
C(9)–S(1)
C(9)–C(8)
C(8)–C(7)
C(7)–C(7A)
1.774(3) Co(1)–Co(2)
1.823(3) Co–C (carbonyl)
1.487(4) C–O (carbonyl)
1.348(4) Co–C (alkyne)
1.434(6)
2.4704(5)
1.784(3)–1.831(4)
1.126(5)–1.135(5)
1.947(3)–1.977(3)
Bond angles (ꢁ)
C(10)–S(1)–C(9)
S(1)–C(9)–C(8)
101.93(15) C(9)–C(8)–C(7)
136.4(3)
115.8(3)
C(8)–C(7)–C(7A) 143.8(3)
Fig. 4. Molecular structure of 5 with partial atom labeling scheme; all
hydrogen atoms have been omitted for clarity.
Atoms with suffix A are generated by symmetry (1 ꢀ x + 2, ꢀy + 1, ꢀz).

4990
V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
the presence of excess HBF4 Æ OEt was carried out.
However, only the bis-capped products, [{Co2(CO)6(l-g2-
(2-S-C5H4NH)CH2C„C–)}2](BF4)2 (6a) or [{Co2(CO)6(l-
g2-(2-S–C5H4N)CH2C„C–)}2] (6b) could be isolated in
moderate to good yields (Scheme 1), the precise identity
being dependent on the work-up employed (see Section
4). Both 6a and 6b have been characterised by LSI mass
1
spectrometry and by H and 13C NMR and IR spectros-
copy (see Table 1 and Section 4). In addition, 6a has been
the subject of a single crystal X-ray diffraction study.
Crystals of 6a suitable for the single crystal X-ray dif-
fraction studies were grown by prolonged standing in a
mixture of tetrahydrofuran and hexane. A view of 6a is
shown in Fig. 5; selected bond lengths and angles are pre-
sented in Table 5. The molecular structure consists of a
dicationic complex and two tetrafluoroborate anions along
with two lattice molecules of THF. The dication is based
on a doubly SR-capped hexa-2,4-diyne chain where the R
groups are pyridinium. Unlike in the straight chain com-
plexes 3 and 5, the Co2C2 cores in 6a are cis to one another
[tors. C(14)–C(15)–C(16)–C(17) 39.7ꢁ] in a manner similar
to that seen in cyclic 4 and other cyclic 1,3-diyne complexes
[10–12,21]. In the case of 6a, the cis-configuration is prob-
ably stabilised by hydrogen-bonding interactions of the
N–H and C–H protons in neighbouring pyridinium groups
with the fluorine atoms of the two BFꢀ4 anions that are
found inside the ‘‘cavity’’ formed by the two pyridinium
Fig. 5. Molecular structure of 6a with partial atom labeling scheme; all
hydrogen atoms apart from H1 and H2, have been omitted for clarity.
lation of polyfunctional primary and secondary amines
with [Co2(CO)6{l-g2-HC„CCH2}](BF4) in protic media
should not proceed as the amino groups would be rendered
inactive due to their complete protonation [13a]. Notably
in this particular reaction, cyclic 4 could also be obtained
(in addition to 5) when the reaction is performed in the
presence of a large excess of HBF4 Æ OEt2; albeit in lower
yield.
Given the observed importance of the 1,2-substitution
pattern of amino/thiohydroxy groups in the above aromat-
ics on macrocyclic formation, we decided to explore the
reaction of 1 with 2-mercaptopyridine. While the pyridine
unit in 2-mercaptopyridine contains no deprotonatable
hydrogen atoms (cf. amino groups in x-NH2–C6H4SH), it
was envisaged that a dual S,N-centred nucleophilic attack
may result via Npyridinium–Cpropargylic bond formation
[14c,20]. Thus, reaction of 1 with 2-mercaptopyridine in
˚
moieties [closest NH(2)ꢁ ꢁ ꢁF contacts: 2.135 and 2.366 A;
˚
closest CHꢁ ꢁ ꢁF contacts: 2.600, 2.653 A]. The pyridinium
N–H proton facing away from the BF4 anions additionally
undergoes a hydrogen bonding interaction [NH(1)ꢁ ꢁ ꢁO
˚
(THF) 1.804 A] with a lattice THF molecule.
1
The H and 13C NMR spectra of 6a and 6b show only
minor changes in chemical shift with a slight downfield
influence on the signals evident in cationic 6a. The pyridi-
nium N–H protons in 6a are visible as a broad downfield
singlet at d 11.0. In the LSI mass spectrum of 6a, peaks cor-
responding to loss of BF4 ions and CO groups from the
proposed molecular ion are evident. A similar carbonyl
fragmentation pattern was observed in the mass spectrum
Table 5
Selected bond distances and angles for 6a
˚
Bond lengths (A)
C(19)–S(1)
C(13)–S(1)
C(13)–C(14)
C(14)–C(15)
C(15)–C(16)
C(16)–C(17)
C(17)–C(18)
C(18)–S(2)
1.734(4)
1.814(3)
1.491(5)
1.354(5)
1.440(5)
1.348(4)
1.488(5)
1.816(3)
Co(1)–Co(2)
Co(3)–Co(4)
C(24)–S(2)
Co–C (carbonyl)
C–O (carbonyl)
Co–C (alkyne)
B–F
2.4512(6)
2.4709(7)
1.744(4)
1.793(4)–1.826(5)
1.129(4)–1.139(5)
1.939(3)–1.967(3)
1.323(6)–1.388(5)
Bond angles (ꢁ)
C(19)–S(1)–C(13)
S(1)–C(13)–C(14)
C(13)–C(14)–C(15)
C(14)–C(15)–C(16)
104.09(17)
106.4(2)
140.9(3)
142.6(3)
C(15)–C(16)–C(17)
C(16)–C(17)–C(18)
C(17)–C(18)–S(2)
C(18)–S(2)–C(24)
141.5(3)
140.5(3)
108.7(2)
101.07(16)

V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
4991
Table 6
Crystallographic and data processing parameters for 3–5 and 6a
Complex
Formula
3
4
5
6a
C30H16Co4N2O12S2
C24H9Co4NO12
S
C30H16Co4N2O12S2
C28H14B2Co4F8N2O12S2Æ
2C4H8O
M
896.29
771.10
896.29
1188.08
Crystal size (mm3)
Temperature (K)
Crystal system
Space group
0.23 · 0.18 · 0.01
180(2)
Triclinic
0.23 · 0.23 · 0.18
180(2)
Monoclinic
C2/c
32.5768(8)
11.4520(5)
16.1133(6)
90
112.499(14)
90
5553.8(3)
8
1.844
3040
2.487
0.28 · 0.23 · 0.12
180(2)
Orthorhombic
Pbca
0.23 · 0.05 · 0.02
180(2)
Triclinic
ꢀ
ꢀ
P1
P1
˚
a (A)
10.2269(4)
15.8376(7)
16.3202(8)
98.283(2)
102.252(2)
91.420(3)
2552.0(2)
3
17.6760(5)
8.3367(2)
23.4759(7)
90
90
90
3459.40(16)
4
1.721
1784
2.068
8.9647(3)
16.3448(7)
16.9189(8)
72.988(2)
78.426(2)
83.341(2)
2318.04(17)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
U (A )
Z
Dl (Mg mꢀ3
F(000)
)
1.750
1338
2.103
1.702
1188
1.592
l(Mo-Ka) (mmꢀ1
)
Reflections collected
Independent reflections
Rint
15410
10328
0.1101
22279
6369
0.0589
12371
3036
0.0549
18033
8010
0.0689
Restraints/parameters
Final R indices (I > 2r(I))
0/676
0/379
0/226
0/613
R1 = 0.0816
wR2 = 0.1914
R1 = 0.1436
wR2 = 0.2440
1.015
R1 = 0.0372
wR2 = 0.0728
R1 = 0.0730
wR2 = 0.0829
0.977
R1 = 0.0343
wR2 = 0.0776
R1 = 0.0511
wR2 = 0.0844
1.049
R1 = 0.0428 wR2 = 0.0686
All data
R1 = 0.0957 wR2 = 0.0869
Goodness-of-fit on F2
1.029
(all data)
2
2 1=2
2
Data in common: graphite-monochromated Mo-Ka radiation, k = 0.71073 A; R1 ¼ RkF oj ꢀ jF ck=RjF oj; wR2 ¼ ½RwðF o ꢀ F 2c Þ =RwðF o2Þ ꢂ ; wꢀ1
¼
˚
2
2
1=2
½r2ðF oÞ þ ðaPÞ ꢂ; P ¼ ½maxðF o2; 0Þ þ 2ðF c2Þꢂ=3, where a is a constant adjusted by the program; goodness of fit ¼ ½RðF o2 ꢀ F 2c Þ2=ðn ꢀ pÞꢂ where n is the
number of reflections and p the number of parameters.
of 6b in addition to a molecular ion peak and a weak peak
due to a M++Na ion. As with other complexes in this work
the IR spectra of 6a and 6b are similar with four bands in
the m(CO) region.
recorded in CDCl3 using a Bruker DRX-500 or a
AM-400 spectrometer with TMS as an external standard
1
1
for H and 13C spectra. H–1H COSY and HMQC NMR
1
1
experiments were employed to obtain H–1H and H–13C
correlated spectra [23]. Infrared spectra were, unless other-
wise stated, recorded in dichloromethane solution in
0.5 mm NaCl solution cells, using a Perkin–Elmer 1710
Fourier Transform Spectrometer. LSI (Liquid Secondary
Ion) mass spectra were recorded on a Micromass Autospec
high resolution double focusing mass spectrometer at the
EPSRC National Mass Spectrometry Service Centre at
the University of Wales Swansea. Electrospray (ESI) mass
spectra were recorded on a Micromass Quattro LC instru-
ment at the University of Cambridge, Mass Spectrometry
Services. Elemental analyses were performed at the Univer-
sity of Cambridge. Column chromatography was per-
formed on Kieselgel 60 (70–230 mesh ASTM). All
products are listed in order of decreasing Rf. The reagents,
2-aminothiophenol, 3-aminothiophenol, 4-aminothiophe-
nol, 2-mercaptopyridine and tetrafluoroboric acid (54
wt.% in diethyl ether) were obtained from Aldrich Chemi-
cal Co. and used without further purification. [{Co2(CO)6-
(l-g2-HOCH2C„C–)}2] (1) was prepared by the literature
method [14].
3. Conclusions
The use of aminothiophenols to facilitate the ring clo-
sure of propargylic cations derived from 1 has been studied
and it has been shown that only the 1,2-substitution pat-
tern can deliver dual N,S-centered nucleophilic attack.
The resultant 10-membered macrocyclic ring complex (4)
has been fully characterised. Attempts to extend this reac-
tivity to 2-mercaptopyridines gave only linear products (6).
4. Experimental
4.1. General procedures and materials
Unless otherwise stated all experiments were carried out
under an atmosphere of dry, oxygen-free argon, using stan-
dard Schlenk line techniques and solvents freshly distilled
from appropriate drying agent [22]. NMR spectra were

4992
V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
4.2. Synthesis of [{Co2(CO)6(l-g2-(3-NH2–C6H4S)-
CH2C„C–)}2] (2)
C24H9Co4NO12S (771.10): C, 37.38; H, 1.17; N, 1.82.
Found: C, 37.53; H, 1.37; N, 1.64%. 13C{1H} NMR
(CDCl3): d 199.8 (CO), 149.4 (C, C6H4), 138.3, 131.4
(CH, C6H4), 122.1 (C, C6H4), 120.6, 114.7 (CH, C6H4),
101.6, 97.2, 93.8, 92.8 (C„C–C„C), 49.3, 45.3 (CH2).
Complex 5: Anal. Calc. for C30H16Co4N2O12S2 (896.29):
C, 40.17; H, 1.79; N, 3.12. Found: C, 40.01; H, 1.96; N,
2.90%. 13C{1H} NMR (CDCl3): d 199.7 (CO), 147.9 (C,
C6H4), 135.2, 130.1, 118.7 (CH, C6H4), 117.7 (C, C6H4),
115.1 (CH, C6H4), 99.6, 91.6 (C„C), 39.4 (CH2).
To a stirred solution of 1 (1.390 g, 2.04 mmol) and
3-aminothiophenol (0.47 ml, 4.50 mmol, 2.2 equiv) in dichlo-
romethane (200 ml) at ꢀ78 ꢁC under argon was added
0.9 ml of 54% HBF4 in diethyl ether. The reaction mixture
was allowed to warm to 0 ꢁC and an excess of NaHCO3
added. Following filtration through a plug of Celite, the
solid residue was washed several times with dichlorometh-
ane until the washings became colourless. The residue was
then extracted with acetonitrile. Careful evaporation of the
acetonitrile solution afforded brown-green crystalline 2
(0.980 g, 52%). Complex 2: Anal. Calc. for C30H16Co4-
N2O12S2 (896.29): C, 40.17; H, 1.79; N, 3.12. Found: C,
40.20; H, 1.83; N, 2.90%. 13C{1H} NMR (CDCl3): d
198.7 (CO), 147.0, 136.8 (C, C6H4), 129.9, 118.6, 114.9,
113.3 (CH, C6H4), 99.9, 92.0 (C„C), 38.4 (CH2). MS
(ESI): m/z 897 (M+H)+.
4.5. Synthesis of [{Co2(CO)6}2{cyclo-l-g2:l-g2-CH2C2C2-
CH2SC6H3–NH-2}] (4)
To a stirred solution of 1 (0.984 g, 1.44 mmol) in dichlo-
romethane (400 ml) at ꢀ78 ꢁC under argon was added
0.8 ml of 54% HBF4 in diethyl ether. After 30 min at
ꢀ78 ꢁC, 2-aminothiophenol (0.155 ml, 1.44 mmol, 1 equiv)
was added and the reaction mixture allowed to warm to
room temperature and an excess of NaHCO3 added. Fol-
lowing filtration through a plug of MgSO4, the solvent
removed under reduced pressure. The residue was re-dis-
solved in the minimum amount of dichloromethane,
adsorbed onto silica and added to the top of a chromatog-
raphy column. Elution with hexane:dichloromethane (4:1)
afforded dark brown crystalline 4 (0.724 g, 65%) as the sole
product.
4.3. Synthesis of [{Co2(CO)6(l-g2-(4-NH2-C6H4S)CH2-
C„C–)}2] (3)
To a stirred solution of 1 (1.378 g, 2.02 mmol) and
4-aminothiophenol (0.629 g, 5.03 mmol, 2.5 equiv) in
dichloromethane (200 ml) at ꢀ78 ꢁC under argon was
added 0.9 ml of 54% HBF4 in diethyl ether. The reaction
mixture was warmed to 0 ꢁC and an excess of NaHCO3
added. Following filtration through a plug of MgSO4, the
filtrate was concentrated and the residue adsorbed onto sil-
ica and then added to the top of a chromatography col-
umn. Elution with hexane:ethyl acetate (1:1) afforded
dark brown-green crystalline 3 (1.47 g, 81%) as the sole
product. Complex 3: Anal. Calc. for C30H16Co4N2O12S2
(896.29): C, 40.17; H, 1.79; N, 3.12. Found: C, 40.27; H,
1.91; N, 2.96%. 13C{1H} NMR (CDCl3): d 198.7 (CO),
146.1 (C, C6H4), 133.2 (CH, C6H4), 123.4 (C, C6H4),
115.7 (CH, C6H4), 100.3, 91.9 (C„C), 41.6 (CH2).
4.6. Synthesis of [{Co2(CO)6(l-g2-(2-S–C5H4NH)CH2-
C„C–)}2](BF4)2 (6a)
To a stirred solution of 1 (0.700 g, 1.03 mmol) and
2-mercaptopyridine (0.250 g, 2.25 mmol, 2.2 equiv) in
dichloromethane (200 ml) at ꢀ78 ꢁC under argon was
added 3.0 ml of 54% HBF4 in diethyl ether. The resulting
mixture was warmed to 0 ꢁC and filtered through a plug
of silica. The residue remaining on the plug was extracted
with ethyl acetate and THF. The organic phases were com-
bined and the solvent was removed on a rotary evaporator
to give dark brown crystalline complex 6a (1.200 g, 98%).
Complex 6a: Anal. Calc. for C28H14Co4N2O12S2B2F8
(1043.35): C, 32.20; H, 1.34; N, 2.68. Found: C, 32.36; H,
1.51; N, 2.52%. 13C{1H} NMR (CDCl3): d 199.5 (CO),
157.5 (C, C5H4NH), 149.5, 136.9, 122.6, 120.3 (CH,
C5H4NH), 103.7, 93.2 (C„C), 34.1 (CH2S).
4.4. Synthesis of [{Co2(CO)6}2{cyclo-l-g2: l-g2-
CH2C2C2CH2SC6H3–NH-2}] (4) and [{Co2(CO)6
(l-g2-(2-NH2–C6H4S)CH2C„C–)}2] (5)
To a stirred solution of 1 (1.223 g, 1.79 mmol) and
2-aminothiophenol
(0.493 g,
0.417 ml,
3.95 mmol,
2.2 equiv) in dichloromethane (400 ml) at ꢀ78 ꢁC under
argon was added 0.8 ml of 54% HBF4 in diethyl ether.
The resulting mixture was warmed to room temperature
and an excess of NaHCO3 added. Following filtration
through a plug of MgSO4, the filtrate was concentrated
under reduced pressure. The residue was re-dissolved in
the minimum amount of dichloromethane, adsorbed onto
silica and added to the top of a chromatography column.
Elution with hexane:ethyl acetate (6:1) afforded dark
brown crystalline 4 (0.480 g, 35%). Further elution with
hexane:ethyl acetate (4:1) yielded dark brown-green crys-
talline 5 (0.820 g, 51%). Complex 4: Anal. Calc. for
4.7. Synthesis of [{Co2(CO)6(l-g2-(2-S–C5H4N)CH2-
C„C–)}2] (6b)
To a stirred solution of 1 (0.450 g, 6.6 mmol) and 2-mer-
captopyridine (0.895 g, 8.1 mmol, 1.2 equiv) in dichloro-
methane (500 ml) at ꢀ78 ꢁC under argon was added
3.0 ml of 54% HBF4 in diethyl ether. The reaction mixture
was warmed to 0 ꢁC and stirred overnight before an excess
of NaHCO3 was added. Following filtration through a plug
of silica, the solvent was removed under reduced pressure.
Crystallisation of the residue from hexane:dichloromethane

V.B. Golovko et al. / Journal of Organometallic Chemistry 692 (2007) 4985–4994
4993
[2] See, for example, (a) S. Tanaka, M. Isobe, Tetrahedron Lett. 35
(1994) 7801;
afforded dark brown-green crystalline 6b (0.234 g, 40%).
Complex 6b: 13C{1H} NMR (CDCl3): d 198.8 (CO),
157.2 (C, C5H4N), 149.2, 136.2, 122.4, 119.9 (CH,
C5H4N), 102.6, 92.4 (C„C), 34.0 (CH2S). 1H NMR
COSY: 8.41–8.40 (7.00), 7.50–7.48 (7.2, 7.00), 7.21–7.20
(7.5, 7.00), 7.00 (7.5, 7.2). HMQC: 8.41–8.40 (149.2),
7.50–7.48 (136.2), 7.21–7.20 (122.4), 7.00 (119.9), 4.83
(34.0).
(b) C. Yenjai, M. Isobe, Tetrahedron 54 (1998) 2509;
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(i) T.F. Jamison, S. Shambayati, W.E. Crowe, S.L. Schreiber, J. Am.
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Single crystal X-ray diffraction data for 3–5 and 6a were
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(b) B.J. Rausch, R. Gleiter, F. Rominger, J. Chem. Soc., Dalton
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sealed tube X-ray source. Cell refinement, data collection
and data reduction were performed with the programs
DENZO [24] and COLLECT [25] and multi-scan absorption
corrections were applied to all intensity data with the pro-
gram SORTAV [26]. All structures were solved and refined
with the programs SHELXS97 and SHELXL97 [27], respec-
tively. Hydrogen atoms were included in calculated posi-
(e) A. Gelling, G.F. Mohmand, J.C. Jeffery, M.J. Went, J. Chem.
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(f) F. Demirhan, S. Irisli, S.N. Salek, O.S. Senturk, M.J. Went,
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˚
tions (C–H = 0.96 A) riding on the bonded atom with
isotropic displacement parameters set to 1.5Ueq(C) for
methyl H atoms and 1.2Ueq(C) for all other H atoms.
Details of the data collection, refinement and crystal data
are listed in Table 6.
(b) M.A. Brook, J. Urschey, M. Stradiotto, Organometallics 17
(1998) 5342;
(c) R.H. Cragg, J.C. Jeffery, M.J. Went, Chem. Commun. (1990) 993;
(d) R.H. Cragg, J.C. Jeffery, M.J. Went, J. Chem. Soc., Dalton
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Acknowledgements
[5] E. Alvaro, M.C. de la Torre, M.A. Sierra, Chem. Commun. (2006)
985.
[6] G.G. Melikyan, M.A. Khan, K.M. Nicholas, Organometallics 14
(1995) 2170.
[7] (a) R. Guo, J.R. Green, J. Chem. Soc., Chem. Commun. (1999) 2503;
(b) R. Gibe, J.R. Green, G. Davidson, Org. Lett. 5 (2003) 1003;
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(d) R. Guo, J.R. Green, Synlett (2000) 746.
We thank the Cambridge Overseas Trust for financial
support to V.B.G. The help of the EPSRC mass spectrom-
etry service, Swansea is gratefully acknowledged. Dr John
E. Davies is thanked for data collection for the crystal
structure determinations.
[8] P.I. Dosa, C. Erben, V.S. Iyer, K.P.C. Vollhardt, I.M. Wasser, J.
Am. Chem. Soc. 121 (1999) 10430.
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Breuning, Chem. Rev. 91 (1991) 1721;
Appendix A. Supplementary material
CCDC 651125, 651124, 651126 and 651123 contain the
supplementary crystallographic data for 3, 4, 5 and 6a.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223 336 033; or
e-mail: deposit@ccdc.cam.ac.uk. Supplementary data associ-
ated with this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2007.07.015.
(b) L.F. Lindoy, Pure Appl. Chem. 69 (1997) 2179;
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625;
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Commun. (1993) 1097.
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Organomet. Chem. 692 (2007) 2076.
[12] L.J. Hope-Weeks, M.J. Mays, C. Paredes, G.A. Solan, Can. J. Chem.,
in press.
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