The spectra, structures and electrochemistry of Ni(η5-C 5H5)(PPh3)-CC-Ar complexes, and their reactions with Co2(CO)8

Article abstract of DOI:10.1016/j.jorganchem.2005.07.045

A series of Ni(η⁵-C₅H₅)(PPh ₃)-CC-Ar complexes, 1 are reported, where Ar = (a) C ₆H₅, (b) 4-PhC₆H₄, (c) 1-C ₁₀H₇ (1-naphthyl), (d) 2-C₁₀H₇ (2-naphthyl), (e) 9-C₁₄H₉ (9-phenanthryl), (f) 9-C ₁₄H₉ (9-anthryl), (g) 1-C₁₆H₉ (1-pyrenyl), (h) 1-C₂₀H₁₁ (1-perylenyl), (i) 2-C ₄H₃S (2-thienyl), (j) C₁₀H₉Fe (ferrocenyl), (k) SiMe₃, and (l) H. 1a-1i react with Co ₂(CO)₈ to give the {Ni(η-C₅H ₅)(PPh₃)-CC-Ar}{Co₂(CO)₆} derivatives 2. All 1 and 2 have been characterised by elemental analysis and spectroscopy (IR, UV-Vis, ¹H NMR and ¹³C NMR), X-ray diffraction for 1e (Ar = 9-phenanthryl), 1j (Ar = ferrocenyl) and 1l (Ar=H), electrochemistry for all 1, and spectroelectrochemistry for 1j.

Full text of DOI:10.1016/j.jorganchem.2005.07.045

Journal of Organometallic Chemistry 690 (2005) 4545–4556
www.elsevier.com/locate/jorganchem
The spectra, structures and electrochemistry
of Ni(g5-C5H5)(PPh3)–C„C–Ar complexes, and their
reactions with Co2(CO)8
a
b
a,
a
Peter Butler , John F. Gallagher , Anthony R. Manning *, Helge Mueller-Bunz ,
c
c
c
C. John McAdam , Jim Simpson , Brian H. Robinson
a
Department of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
b
School of Chemical Sciences, Dublin City University, Dublin 9, Ireland
Department of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand
c
Received 13 May 2005; received in revised form 22 June 2005; accepted 4 July 2005
Available online 22 August 2005
Abstract
A series of Ni(g5-C5H5)(PPh3)–C„C–Ar complexes, 1 are reported, where Ar = (a) C6H5, (b) 4-PhC6H4, (c) 1-C10H7
(1-naphthyl), (d) 2-C10H7 (2-naphthyl), (e) 9-C14H9 (9-phenanthryl), (f) 9-C14H9 (9-anthryl), (g) 1-C16H9 (1-pyrenyl), (h)
1-C20H11 (1-perylenyl), (i) 2-C4H3S (2-thienyl), (j) C10H9Fe (ferrocenyl), (k) SiMe3, and (l) H. 1a–1i react with Co2(CO)8 to give
the {Ni(g-C5H5)(PPh3)–C„C–Ar}{Co2(CO)6} derivatives 2. All 1 and 2 have been characterised by elemental analysis and spec-
troscopy (IR, UV–Vis, 1H NMR and 13C NMR), X-ray diffraction for 1e (Ar = 9-phenanthryl), 1j (Ar = ferrocenyl) and 1l
(Ar=H), electrochemistry for all 1, and spectroelectrochemistry for 1j.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Nickel; Alkynyl complexes; Polycyclic aromatic hydrocarbons; Cobalt complexes; Electrochemistry
1. Introduction
Ni(g5-C5H5)(PPh3)–C„C–C6H5, 1a, does not appear
to be particularly effective in this respect [3].
The acetylide linkage in Ni(g5-C5H5)(PPh3)–C„C–X
complexes, and related compounds such as Ni(g5-
C5H5)(PPh3)–C„C–C6H4–X, allows facile electronic
communication between the electron-rich Ni(g5-
C5H5)(PPh3) moiety and X which can affect the charac-
teristic chemistry of both X and C„C [1]. However, if X
is an electron-withdrawing group the molecule is a
donor-p-acceptor (D–p–A) system which may have
non-linear optical (NLO) properties [2], although
We have shown that polycyclic aromatic hydrocar-
bon residues containing 1–5 aromatic rings (e.g., 3-pyre-
nyl) can act as an electron-donor endgroup in D–p–A
systems in the presence of suitable acceptors [4], and
were interested to see if it is possible for them to act
as acceptors in the presence of a Ni(g5-C5H5)(PPh3) do-
nor. Although the results reported for 1a were not
encouraging [3], there was the possibility that more
highly annelated PAH end-groups would prove to be
better acceptors than Ph. Furthermore, our electro-
chemical/OTTLE studies on a series of Fc–C„C–Ar
(Fc = ferrocenyl) derivatives showed they, or more par-
ticularly their [Fc–C„C–Ar]+ derivatives, have unusual
spectroscopic properties [5], which might also be found
in their Ni(g5-C5H5)(PPh3)–C„C–Ar counterparts.
*
Corresponding author.
E-mail addresses: John.Gallagher@dcu.ie (J.F. Gallagher), Anthony.
Manning@ucd.ie (A.R. Manning), brobinson@alkali.otago.ac.nz
(B.H. Robinson).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.07.045

4546
P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
Consequently we prepared a series of Ni(g5-C5H5)
(PPh3)–C„C–Ar complexes 1, where Ar = (a) C6H5,
(b) 4-PhC6H4, (c) 1-C10H7 (1-naphthyl), (d) 2-C10H7
(2-naphthyl), (e) 9-C14H9 (9-phenanthryl), (f) 9-C14H9
(9-anthryl), (g) 3-C16H9 (3-pyrenyl), (h) 1-C20H11 (1-per-
ylenyl), (i) 2-C4H3S (2-thienyl), and (j) C10H9Fe
(ferrocenyl). They have been characterised by spectro-
scopic and electrochemical data, and the molecular
structures of a number of them determined by X-ray dif-
fraction. 1 have been reacted with Co2(CO)8 to give
{Ni(g5-C5H5)(PPh3)–C„C–Ar}{Co2(CO)6} derivatives
2.
(0.22 mmol) and a catalytic amount of CuI (5 mg) in tri-
ethylamine (50 ml) was stirred in the absence of light for
16 h. The solvent was then removed under reduced pres-
sure, and the residue was dissolved in dichloromethane
and chromatographed on basic alumina using dichloro-
methane/diethylether (1:1) to elute [(g5-C5H5)(PPh3)Ni–
C„C–Ar, 1, where Ar = (a) C6H5, (b) 4-PhC6H4, (c)
1-C10H7 (1-naphthyl), (d) 2-C10H7 (2-naphthyl), (e)
9-C14H9 (9-phenanthryl), (f) 9-C14H9 (9-anthryl), (g)
3-C16H9 (3-pyrenyl), (h) 1-C20H11 (1-perylenyl), (i)
2-C4H3S (2-thienyl), and (j) C10H9Fe (ferrocenyl). These
were recrystallised from CH2Cl2–pentane mixtures.
[(g5-C5H5)(PPh3)Ni–C„C–SiMe3, 1k, was prepared
similarly from Ni(gC5H5)(PPh3)Br and trimethylsilyl-
acetylene. The terminal acetylide 1l, was prepared by
hydrolysis of a solution of 1k (0.36 g, 0.072 mmol) in
methanol (20 ml) with K2CO3 (2 mmol) for 5 h. The sol-
vent was removed from the reaction mixture at reduced
pressure, and the residue extracted with dichlorometh-
ane. The solution was filtered through a pad of anhy-
drous magnesium sulfate and the solvent removed at
reduced pressure to give green [(g5-C5H5)(PPh3)Ni–
C„C–H, 1l, previously prepared by a different route
[9]. Any further attempts at purification of this com-
pound gave a less pure product.
2. Experimental
Published procedures or extensions thereof were used
to prepare Ni(g-C5H5)(PPh3)Br [6] and ArC„CH [7]
{Ar = 4-C6H5C6H4, 4-Me2NC6H4, 1-C10H7 (1-naph-
thyl), 2-C10H7 (2-naphthyl), 9-C14H9 (9-phenanthryl),
9-C14H9 (9-anthryl), 3-C16H9 (3-pyrenyl), 1-C20H11 (1-
perylenyl), 2-C4H3S (2-thienyl), and C10H9Fe (ferroce-
nyl)}. Other chemicals were purchased and used as
received.
Unless it is stated otherwise, all reactions were carried
out at room temperature in the dark under an atmo-
sphere of nitrogen in dried and deoxygenated solvents.
They were monitored by IR spectroscopy. Infrared spec-
tra were recorded on a Perkin–Elmer Paragon 1000
FTIR spectrometer. UV–Vis spectra were recorded on
a UNICAM UV2 spectrometer. NMR spectra were ob-
tained on a Jeol JNM-GX270 FT-NMR spectrometer.
1H (270 MHz) and 13C (67.8 MHz) chemical shifts are
reported downfield from tetramethylsilane as internal
standard with coupling constants in Hertz. Elemental
analyses were performed in the Microanalytical Labora-
tory, University College Dublin.
2.1.1. Ni(g5-C5H5)(PPh3)–C„C–C6H5 (1a)
Yield = 80% (Found: C, 76.4; H, 5.1%; C31H25NiP
requires C, 76.4; H, 5.1%). IR m/cmꢁ1: m(C„C) 2099
1
(CH2Cl2); m(C„C) 2098 (KBr). H NMR (CDCl3): d
6.64–7.72 [20H, m, C6H5 and PPh3], 5.24 [5H, s,
C5H5]. 13C NMR (CDCl3): d 124.6–134.0 [m, C6H5,
PPh3], 119.6 [s, Ni–C„C], 92.5 [s, C5H5], 86.2 [d,
2JCP = 48 Hz, Ni–C]. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 271
(19000), 290 (sh), 316 (sh, 17000), 422 (1210) in CH2Cl2;
420 (1200) in CH3CN.
Cyclic and square wave voltammetry in CH2Cl2 were
performed using a three-electrode cell with a polished Pt
1 mm disk working electrode; solutions were ꢀ10ꢁ3 M
in electroactive material and 0.10 M in supporting elec-
trolyte (recrystallised TBAPF6). Data was recorded on
an EG & G PAR 273A or Powerlab/4sp computer-con-
trolled potentiostat. Scan rates of 0.05–1 V sꢁ1 were typ-
ically employed for cyclic voltammetry and for square-
wave voltammetry, square-wave step heights of 5 mV,
a square amplitude of 25 mV with a frequency of
15 Hz. All potentials are referenced to decamethylferro-
cene against which E1/2 for sublimed ferrocene was
0.55 V. Infrared and UV–Vis OTTLE data were ob-
tained from standard cells with platinum grid electrodes.
2.1.2. Ni(g5-C5H5)(PPh3)–C„C–C6H4–C6H5-4 (1b)
Yield = 80% (Found: C, 79.5; H, 5.3%; C37H29NiP
requires C, 79.2; H, 5.2%). IR m/cmꢁ1: m(C„C) 2096
1
(CH2Cl2); m(C„C) 2095 (KBr). H NMR (CDCl3): d
6.67–7.79 [24H, m, C6H5, C6H4 and PPh3], 5.26 [5H, s,
C5H5]. 13C NMR (CDCl3): d 120.7–142.0 [m, C6H5,
PPh3], 119.7 [s, Ni–C„C], 92.7 [d, JCP = 2.1 Hz,
2
C5H5], 87.5 [d, JCP = 49.5 Hz, Ni–C].
2.1.3. Ni(g-C5H5)(PPh3)–C„C–C10H7 (1c)
(C10H7 = 1-naphthyl)
Yield = 70% (Found: C, 78.6; H, 5.1%; C35H27NiP
requires C, 78.2; H, 5.1%). IR m/cmꢁ1: m(C„C) 2084
1
(CH2Cl2); m(C„C) 2085 (KBr). H NMR (CDCl3): d
2.1. Preparation of (g5-C5H5)(PPh3)Ni–CC–Ar [8]
4.58–7.79 [22H, m, C10H7, and PPh3], 5.21 [5H, s,
C5H5]. 13C NMR (CDCl3): d 124.7–134.8 [m, C10H7,
solution of equimolar amounts of Ni(g5-
C5H5)(PPh3)Br (0.1 g, 0.22 mmol) and ArCCH
PPh3], 118.0 [s, Ni–C„C], 92.9 [d, JCP = 2.1 Hz,
A
2
C5H5], 91.1 [d, JCP = 48.5 Hz, Ni–C].
kmax/nm

P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
4547
1
(e/dm3 molꢁ1 cmꢁ1) 312 (21000), 330 (16000), 361
(11400), 425 nm (1670) in CH2Cl2.
(CH2Cl2); m(C„C) 2081 (KBr). H NMR (CDCl3): d
6.97–8.07 [26H, m, C20H11 and PPh3], 5.31 [5H, s,
C5H5]. 13C NMR (CDCl3): d 119.6–135.1 [m, C6H5,
PPh3], 119.5 [s, Ni–C„C], 92.9 [s, C5H5], 95.2 [d,
2.1.4. Ni(g-C5H5)(PPh3)–C„C–C10H7 (1d)
(C10H7 = 2-naphthyl)
2JCP = 47.5 Hz, Ni–C]. kmax/nm (e/dm3 molꢁ1 cmꢁ1
)
Yield = 80% (Found: C, 78.2; H, 5.1%; C35H27NiP
requires C, 78.2; H, 5.1%). IR m/cmꢁ1: m(C„C) 2084
(CH2Cl2); m(C„C) 2085 (KBr). 1H NMR (CDCl3):
d 6.70–7.80 [22H, m, C10H7, and PPh3], 5.28 [5H, s,
C5H5]. 13C NMR (CDCl3): d 125.6–135.2 [m, C10H7,
433 (sh, 11000), 458 (21300), 486 (28000) in CH2Cl2.
2.1.9. Ni(g5-C5H5)(PPh3)–C„C–C4H3S (1i)
(C4H3S = 2-thienyl)
Yield = 70% (Found: C, 70.0; H, 4.8%; C29H25NiPS
PPh3], 118.7 [s, Ni–C„C], 92.7 [d, JCP = 2.2 Hz,
requires C, 70.0; H, 4.8%). IR m/cmꢁ1: m(C„C) 2086
2
1
C5H5], 87.8 [d, JCP = 49.5 Hz, Ni–C].
k
max/nm
(CH2Cl2); m(C„C) 2084 (KBr). H NMR (CDCl3): d
(e/dm3 molꢁ1 cmꢁ1) 310 (22800), 331 (15700), 358
6.36–7.76 [20H, m, C4H3S and PPh3], 5.24 [5H, s,
C5H5]. 13C NMR (CDCl3): d 122.1–134.3 [m, C4H3S,
PPh3], 92.7 [d, JCP = 2.1 Hz, C5H5], 92.8 [d,
2JCP = 48 Hz, Ni–C].
(11200), 429 nm (1540) in CH2Cl2.
2.1.5. Ni(g-C5H5)(PPh3)–C„C–C14H9 (1e)
(C14H9 = 9-phenanthryl)
Yield = 80% (Found: C, 79.8; H, 5.0%; C39H29NiP
requires C, 79.8; H, 5.0%). IR m/cmꢁ1: m(C„C) 2090
(CH2Cl2); m(C„C) 2091 (KBr). 1H NMR (CDCl3):
d 7.21–8.69 [24H, m, C14H9, and PPh3], 5.32 [5H, s,
C5H5]. 13C NMR (CDCl3): d 117.5–135.0 [m, C14H9,
2.1.10. Ni(g5-C5H5)(PPh3)–C„C–C10H9Fe (1j)
(C10H9 = ferrocenyl)
Yield = 95% (Found: C, 70.2; H, 5.1%; C35H29FeNiP
requires C, 70.6; H, 5.2%). IR m/cmꢁ1: m(C„C) 2102
1
(CH2Cl2); m(C„C) 2099 (KBr). H NMR (CDCl3): d
PPh3], 118.0 [s, Ni–C„C], 92.8 [d, JCP = 2.1 Hz,
7.40–7.87 [15H, m, PPh3], 5.19 [5H, s, C5H5Ni], 3.78
[4H, m, C5H4Fe], 3.61 [5H, s, C5H5Fe]. 13C NMR
(CDCl3): d 128.1–134.7 [m, PPh3], 115.2 [s, Ni–C„C],
92.6 [d, JCP = 2.2 Hz, C5H5Ni], 66.5, 70.3, 73.6 [all s,
2
C5H5], 91.4 [d, JCP = 48.5 Hz, Ni–C].
kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 334 (11000), 368 (8600), 420 nm
(sh, 1340) in CH2Cl2.
C5H4Fe], 69.0 [s, C5H5Fe]. kmax/nm (e/dm3 molꢁ1 cmꢁ1
)
2.1.6. Ni(g-C5H5)(PPh3)–C„C–C14H9 (1f)
(C14H9 = 9-anthryl)
424 (1100) in CH2Cl2.
Yield = 80% (Found: C, 80.4; H, 5.2%; C39H29NiP
requires C, 79.8; H, 5.0%). IR m/cmꢁ1: m(C„C) 2075
(CH2Cl2); m(C„C) 2075 (KBr). 1H NMR (CDCl3):
d 7.06–8.00 [24H, m, C14H9, and PPh3], 5.37 [5H, s,
C5H5]. 13C NMR (CDCl3): d 122.6–134.4 [m, C14H9,
2.1.11. Ni(g5-C5H5)(PPh3)–C„C–SiMe3 (1k)
Yield = 75% (Found: C, 69.6; H, 6.1, P, 6.2%;
C28H29NiPSi requires C, 69.6; H, 6.1; P, 6.4%). IR
m/cmꢁ1: m(C„C) 2026 (CH2Cl2). 1H NMR (CDCl3):
d 7.3–7.7 [15H, m, PPh3], 5.17 [5H, s, C5H5], ꢁ0.37
[9H, s, SiMe3]. 13C NMR (CDCl3): d 128.1–134.1 [m,
PPh3], 116.9 [s, Ni–C„C], 92.9 [d, JCP = 2.2 Hz,
2
2
C5H5], 99.0 [d, JCP = 48.5 Hz, Ni–C].
k
max/nm
PPh3], 110.6 [d, JCP = 46 Hz, Ni–C], 92.5 [s, C5H5],
(e/dm3 molꢁ1 cmꢁ1) 258 (50000), 387 (sh, 5300), 411
0.8 [s, SiMe3]. 31P NMR (CDCl3): d 41.9. kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 416 nm (1060) in CH2Cl2.
(sh, 8700), 433 (sh, 12400) 449 nm (13700) in CH2Cl2.
2.1.7. Ni(g-C5H5)(PPh3)–C„C–C16H9 (1g)
(C16H9 = 3-pyrenyl)
2.1.12. Ni(g5-C5H5)(PPh3)–C„C–H (1l)
Yield = 82% (Found: C, 72.9; H, 5.4; P, 7.5%;
C25H21NiP requires C, 73.0; H, 5.2; P, 7.5%). IR
m/cmꢁ1: m(C„C) 1959, m(CC–H) 3276 cmꢁ1 (CH2Cl2).
1H NMR (CDCl3): d 7.4–7.7 [15H, m, PPh3], 5.18 [5H,
Yield = 80% (Found: C, 80.1; H, 4.9%; C41H29NiP
requires C, 80.5; H, 4.8%). IR m/cmꢁ1: m(C„C) 2081
(CH2Cl2); m(C„C) 2080 (KBr). 1H NMR (CDCl3):
d 7.30–8.20 [24H, m, C16H9, and PPh3], 5.35 [5H, s,
C5H5]. 13C NMR (CDCl3): d 124.4–135.1 [m, C16H9,
4
s, C5H5], 1.47 [1H, d, JPH = 2 Hz, CCH]. 13C NMR
(CDCl3): d 128.1–133.8 [m, C6H5, PPh3], 105.0 [s, Ni–
2
PPh3], 119.9 [s, Ni–C„C], 93.6 [d, JCP = 2.2 Hz,
C„C], 92.6 [s, C5H5], 80.8 [d, JCP = 46 Hz, Ni–C].
2
C5H5], 94.3 [d, JCP = 47.5 Hz, Ni–C].
k
max/nm
31P NMR (CDCl3): d 42.0. kmax/nm (e/dm3 molꢁ1 cmꢁ1
)
(e/dm3 molꢁ1 cmꢁ1) 254, 280 (26000), 293 (24000), 350
(15900), 367 (17500), 388 (19600), 416 (19400) in
CH2Cl2.
417 nm (1060) in CH2Cl2.
2.2. Reaction of Ni(g5-C5H5)(PPh3)–CBC–Ar (1), with
Co2(CO)8
2.1.8. Ni(g5-C5H5)(PPh3)–C„C–C20H11 (1h)
(C20H11 = 3-perylenyl)
Yield = 80% (Found: C, 81.4; H, 4.7%; C45H31NiP
requires C, 81.7; H, 4.7%). IR m/cmꢁ1: m(C„C) 2081
Equimolar amounts of Ni(g5-C5H5)(PPh3)–C„C–Ar
(0.02 mmol) and Co2(CO)8 (0.07 g, 0.02 mmol) in
dichloromethane (30 ml) were stirred for 1 h. The

4548
P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
solvent was removed under reduced pressure, and the
residue chromatographed on alumina using hexane to
elute any unreacted Co2(CO)8 and dichloromethane to
elute the product as a brown/red band. Removal of
the solvent and recrystallisation of the residue from
diethylether gave brown {Ni(g5-C5H5)(PPh3)–C„C–
Ar}{Co2(CO)6} (2) where Ar = (a) C6H5, (b) 4-PhC6H4,
(d) 1-C10H7 (1-naphthyl), (e) 2-C10H7 (2-naphthyl), (f)
9-C14H9 (9-phenanthryl), (g) 9-C14H9 (9-anthryl), (h)
3-C16H9 (3-pyrenyl), (i) 1-C20H11 (1-perylenyl) and
(j) 2-C4H3S (2-thienyl). {Ni(g5-C5H5)(PPh3)–C„C–H}
{Co2(CO)6} (2l) could be prepared but as it was very
unstable and decomposed rapidly, only its IR spectrum
could be measured.
2.2.5. {Ni(g-C5H5)(PPh3)–C„C–C14H9}{Co2(CO)6}
(2e) (C14H9 = 9-phenanthryl)
Yield = 50% (Found: C, 61.9; H, 3.3%; C45H29Co2-
NiO6P requires C, 61.9; H, 3.3%). IR m/cmꢁ1: m(CO)
2061, 2032, 1995 in CH2Cl2; 2062, 2032, 1996 in KBr.
1H NMR (CDCl3): d 7.00–8.24 [24H, m, C14H9 and
PPh3], 5.19 [5H, s, C5H5]. 13C NMR (CDCl3): d 204.6
(s, CO), 121.9–133.9 [m, C14H9, PPh3], 112.1 [s, Ni–
2
C„C], 93.9 [s, C5H5], 80.5 [d, JCP = 48 Hz, Ni–C].
2.2.6. {Ni(g-C5H5)(PPh3)–C„C–C14H9}{Co2(CO)6}
(2f) (C14H9 = 9-anthryl)
Yield = 55% (Found: C, 61.7; H, 3.3%; C45H29Co2-
NiO6P requires C, 61.9; H, 3.3%). IR m/cmꢁ1: m(CO)
2060, 2030, 1989 in CH2Cl2; 2062, 2031, 1990 in KBr.
1H NMR (CDCl3): d 6.93–7.82 [24H, m, C14H9 and
PPh3], 5.20 [5H, s, C5H5]. 13C NMR (CDCl3): d 204.1
(s, CO), 122.1–134.9 [m, C14H9, PPh3], 109.7 [s, Ni–
2.2.1. {Ni(g-C5H5)(PPh3)–C„C–C6H5}{Co2(CO)6}
(2a)
Yield = 50% (Found: C, 57.3; H, 3.2%; C37H25Co2-
NiO6P requires C, 57.5; H, 3.2%). IR m/cmꢁ1: m(CO)
2065, 2030, 1998 in CH2Cl2; 2064, 2030, 1999 in KBr.
1H NMR (CDCl3): d 6.95–7.62 [20H, m, C6H5 and
PPh3], 5.19 [5H, s, C5H5]. 13C NMR (CDCl3): d 205.8
(s, CO), 124.3–138.6 [m, C6H5, PPh3], 94.9 [s, C5H5],
2
C„C], 94.7 [s, C5H5], 83.6 [d, JCP = 48 Hz, Ni–C].
2.2.7. {Ni(g-C5H5)(PPh3)–C„C–C16H9}{Co2(CO)6}
(2g) (C16H9 = 3-pyrenyl)
Yield = 55% (Found: C, 62.6; H, 3.3%; C47H29Co2-
NiO6P requires C, 62.9; H, 3.2%). IR m/cmꢁ1: m(CO)
2058, 2030, 1990 in CH2Cl2; 2060, 2030, 1991 in
2
80.2 [d, JCP = 48 Hz, Ni–C], 76.5 [s, Ni–C„C].
1
2.2.2. {Ni(g-C5H5)(PPh3)–C„C–C6H4–C6H5-
4}{Co2(CO)6} (2b)
KBr. H NMR (CDCl3): d 6.96–7.82 [24H, m, C16H9
and PPh3], 5.22 [5H, s, C5H5]. 13C NMR (CDCl3): d
205.3 (s, CO), 122.3–135.8 [m, C16H9, PPh3], 110.5
Yield = 60% (Found: C, 60.5; H, 3.4%; C43H29Co2-
NiO6P requires C, 60.8; H, 3.4%). IR m/cmꢁ1: m(CO)
2066, 2033, 1997 in CH2Cl2; 2065, 2032, 1997 in KBr.
1H NMR (CDCl3): d 7.10–7.82 [24H, m, C6H5,C6H4
and PPh3], 5.21 [5H, s, C5H5]. 13C NMR (CDCl3): d
203.6 (s, CO), 123.6–134.2 [m, C6H5, C6H4, PPh3],
2
[s, Ni–C„C], 94.4 [s, C5H5], 83.3 [d, JCP = 48 Hz,
Ni–C].
2.2.8. {Ni(g-C5H5)(PPh3)–C„C–C20H11}{Co2(CO)6}
(2h) (C20H11 = 3-perylenyl)
2
94.6 [s, C5H5], 81.5 [d, JCP = 48 Hz, Ni–C], 76.5 [s,
Yield = 45% (Found: C, 64.3; H, 3.4%; C51H31Co2-
NiO6P requires C, 64.7; H, 3.3%). IR m/cmꢁ1: m(CO)
2058, 2031, 1991 in CH2Cl2; 2059, 2030, 1992 in KBr.
1H NMR (CDCl3): d 7.10–7.91 [26H, m, C20H11 and
PPh3], 5.21 [5H, s, C5H5]. 13C NMR (CDCl3): d 203.9
(s, CO), 123.6–135.3 [m, C20H11, PPh3], 109.6 [s, Ni–
Ni–C„C].
2.2.3. {Ni(g-C5H5)(PPh3)–C„C–C10H7}{Co2(CO)6}
(2c) (C10H7 = 1-naphthyl)
Yield = 60% (Found: C, 59.6; H; 3.2%; C41H27Co2-
NiO6P requires C, 59.8; H, 3.3%). IR m/cmꢁ1: m(CO)
2067, 2033, 1996 in CH2Cl2; 2066, 2032, 1997 in KBr.
1H NMR (CDCl3): d 6.65–7.71 [22H, m, C10H7 and
PPh3], 5.20 [5H, s, C5H5]. 13C NMR (CDCl3): d 204.6
(s, CO), 122.6–135.6 [m, C10H7, PPh3], 94.5 [s, C5H5],
2
C„C], 94.5 [s, C5H5], 85.1 [d, JCP = 48 Hz, Ni–C].
2.2.9. {Ni(g-C5H5)(PPh3)–C„C–C4H3S}{Co2(CO)6}
(2i) (C4H3S = 2-thienyl)
2
Yield = 30% (Found: C, 53.8; H, 3.0%; C35H23Co2-
NiO6P requires C, 53.9; H, 3.0%). IR m/cmꢁ1: m(CO)
2064, 2034, 2001 in CH2Cl2; 2064, 2035, 2001 in KBr.
1H NMR (CDCl3): d 6.12–7.71 [18H, m, C4H3 and
PPh3], 5.21 [5H, s, C5H5]. 13C NMR (CDCl3): d 202.6
(s, CO), 120.5–136.6 [m, C4H3, PPh3], 99.2 [s, Ni–
90.1 [s, Ni–C„C], 82.4 [d, JCP = 48 Hz, Ni–C].
2.2.4. {Ni(g-C5H5)(PPh3)–C„C–C10H7}{Co2(CO)6}
(2d) (C10H7 = 2-naphthyl)
Yield = 60% (Found: C, 59.8; H, 3.4%; C41H27Co2-
NiO6P requires C, 59.8; H, 3.3%). IR m/cmꢁ1: m(CO)
2065, 2031, 1991 in CH2Cl2; 2065, 2030, 1992 in KBr.
1H NMR (CDCl3): d 7.05–7.68 [22H, m, C10H7 and
PPh3], 5.22 [5H, s, C5H5]. 13C NMR (CDCl3): d 204.1
(s, CO), 124.2–136.0 [m, C10H7, PPh3], 100.1 [s, Ni–
2
C„C], 93.9 [s, C5H5], 84.2 [d, JCP = 48 Hz, Ni–C].
2.2.10. {Ni(g-C5H5)(PPh3)–C„C–H}{Co2(CO)6}
(2l)
IR m/cmꢁ1: m(CO) 2061, 2022, 1991 in CH2Cl2.
2
C„C], 94.2 [s, C5H5], 83.7 [d, JCP = 48 Hz, Ni–C].

P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
4549
2.3. Structure determinations for 1e, 1j and 1l
pentadienyl ligand coordinated to the Ni atom of mole-
cule A and the two sites (occupancy 0.52:0.48) were
treated using soft DELU/ISOR/FLAT restraints in the
final stages of refinement. For this structure, graphics
were obtained using ORTEX [16] and PLATON [17].
Molecular structures of 1e,1j and 1l with atom label-
ling are shown in Figs. 1–3, and selected bond lengths
and angles in Table 2.
Green crystals of 1e and1j were grown from dichloro-
methane–hexane mixtures by diffusion, and of 1l from
chloroform–hexane mixtures. Crystal data for 1e, 1j
and 1l are given in Table 1.
A block of 1e, a plate of 1j, and a block of 1l, were
used for data collection. Data were collected on a Bru-
ker SMART CCD at 183(2) K for 1e, an Enraf-Nonius
CAD-4 at 294(2) K for 1j [10] and a Bruker SMART
APEX CCD at 100(2) K for 1l. Data for 1e and 1l were
processed using SMART [11] with empirical absorption
corrections applied using SADABS [12]. For 1j data were
processed using the NCRVAX suite of programs and the
ABSORP routine to apply absorption corrections [13].
All three structures were solved using SHELXS-97 [14]
and refined by full-matrix least-squares using SHELXL-
97 [15]. All non-hydrogen atoms were assigned aniso-
tropic temperature factors with hydrogen atoms
included in calculated positions using a riding model.
There are two independent molecules in the unit cell of
1j, designated A and B. Disorder is present in the cyclo-
3. Results and discussion
The reactions carried out in this work are shown in
the Scheme 1. The alkynyl–nickel complexes 1, are air-
stable solids which are insoluble in water but soluble
in common organic solvents with their solubility
decreasing with increasing size of the Ar group. All
are green with the exception of 1i, which is orange.
The alkynes 1 react with Co2(CO)8 in the usual fash-
ion [18] to give {Ni(g5-C5H5)(PPh3)–C„C–Ar}{Co2-
(CO)6}, 2, which have structures similar to that of
{Ni(g5-C5H5)(PPh3)–C„C–CHO}{Co2(CO)6} [1]. Ni
Table 1
Crystal data for Ni(g5-C5H5)(PPh3)–C„C–C14H9 (1e), Ni(g5-C5H5)(PPh3)C„C–Fc (1j) and Ni(g5-C5H5)(PPh3)–C„C–H 1l
Ni(g5-C5H5)(PPh3)–C„C–C14H9 (1e)
Ni(g5-C5H5)(PPh3)C„C–Fc (1j)
Ni(g5-C5H5)(PPh3)–C„C–H (1l)
Empirical formula
Formula weight
Temperature (K)
C
587.30
183(2)
39H29NiP
C35H29FeNiP
595.11
293(2)
C25H21NiP
411.10
100(2)
˚
Wavelength (A)
0.71073
Monoclinic
P21/c
0.71093
Monoclinic,
P21/n
0.71073
Orthorhombic
Pbca
Crystal system
Space group
Unit cell dimensions
˚
a (A)
11.056(3)
24.614(6)
11.422(3)
9.7458(10)
29.928(3)
19.620(2)
9.4694(9)
16.4972(16)
25.313(3)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
90
3954.4(7)
107.875(4)
103.796(8)
3
˚
V (A )
Z
2958.2(12)
4
1.319
0.736
5557.7(10)
8
1.422
1.280
2464
8
Calculated density (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
1.381
1.068
1712
)
1224
Crystal size (mm)
h Range for data collection (ꢁ)
Index ranges (hkl)
0.70 · 0.36 · 0.32
2.05–26.48
0.24 · 0.22 · 0.05
2.5–25.1
0.70 · 0.40 · 0.20
1.61–28.26
ꢁ12 ! 13, ꢁ30 ! 30, ꢁ14 ! 14
ꢁ11 ! 11, 0 ! 35, 0 ! 25
ꢁ12 ! 12, ꢁ21 ! 21, ꢁ33 ! 32
Reflections collected
36417
10176
30439
Independent reflections [Rint
Data completeness
Absorption correction
Maximum and minimum
transmission
]
6032 [0.0577]
2h = 52.96ꢁ, 98.6%
Multiscan
9953 [0.023]
2h = 56ꢁ, 99%
Numerical
0.933 and 0.749
4688 [0.0642]
2h = 56.52ꢁ, 95.6%
Semi-empirical from equivalents
0.8147 and 0.4666
1.000 and 0.829
Refinement method
Full-matrix least-squares on F2
6032/0/370
Full-matrix least-squares on F2
9953/84/731
Full–matrix least–squares on F2
4688/0/244
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2 (I)]
R indices (all data)
1.025
0.90
1.296
R1 = 0.0387, wR2 = 0.0754
R1 = 0.0696, wR2 = 0.0852
0.29 and ꢁ0.35
R1 = 0.0537, wR2 = 0.0851
R1 = 0.1955, wR2 = 0.1053
0.44 and ꢁ0.43
R1 = 0.0791, wR2 = 0.1556
R1 = 0.0974, wR2 = 0.1608
1.015 and ꢁ1.478
Largest difference in peak
ꢁ3
˚
and hole (e A
)
Largest shift/error max.
<0.001
0.001

4550
P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
Ar
C
Co
Co
(i)
(ii)
C
Ni
Ni Br
PPh3
Ni
C
C
Ar
PPh3
PPh3
1
2
Scheme 1. (i) ArCCH/Et3N/CuI; (ii) Co2(CO)8/CH2Cl2 (CO ligands have been omitted for clarity).
C6
C7
C23
C8
C9
C22
C5
C4
C24
C3
C21
C2
C1
Ni1
P2
C20
C10
C11
C16
C12
C13
C15
C30
C40
C41
C51
C14
C50
C31
Fig. 1. The structure and atom labelling of Ni(g-C5H5)(PPh3)–C„C–C14H9 (1e).
and Ar are attached to the C atoms of the dicobaltatet-
rahedrane core of the molecule. All are dark brown
solids soluble in the usual organic solvents. They are
somewhat air-sensitive in the solid state and much more
so in solution.
[19–22]. In particular, the dimensions of Ni(g5-C5H5)-
(PPh3)–C„C–H, 1l, are very similar to those of Ni(g5-
C5H5)(PPh3)–C„C–C„C–H [20].
In Ni(g5-C5H5)(PPh3)–C„C–H, 1l, the C5H5 and
Ph3P–Ni–C„CH planes have an angle of 85.6ꢁ between
them and are oriented so that the P–Ni–C plane is at
right-angles to the av plane of the g5-C5H5, i.e., a b iso-
mer [1]. As a consequence the cyclopentadienyl ring is
distorted towards an ene-enyl moiety. The reasons for
this are discussed elsewhere, [23 and references therein].
In Ni(g5-C5H5)(PPh3)–C„C–C14H9-9, 1e, the angle
between the P–Ni–C(1)„C(2) and cyclopentadienyl
planes is 89.8ꢁ. The phenanthryl fragment is also planar
and its plane is close to that of the P–Ni–C(1)–C(2) moi-
ety with an angle of 12.1ꢁ between them. This is similar
to the situation in 1a [22] and contrasts with that in
Ni(g5-C5H5)(PPh3)–C„C–CH(CN)2 [1], where the P–
Ni–C(1)„C(2) and CH(CN)2 planes are close to orthog-
onal. The P–Ni–C(1) plane is oriented such that it is
coincident with the av plane of the C5 ring and is an
ab isomer [1] with the Ni–P bond eclipsing C(21). The
C5 ring is distorted towards a diene with two short
3.1. Molecular structures of the alkynyl–Ni complexes 1e,
1j and 1l
The molecular structures of 1e, 1j and their parent 1l
are illustrated in Figs. 1–3. Selected bond lengths and
angles are given in Table 2.
All three compounds have the expected two-legged
piano-stool structure with a planar g5-cyclopentadienyl
ligand coordinated to a planar P–Ni–C„C moiety such
that the two planes are approximately. orthogonal.
Ni–C„C are virtually linear, 174.0(3)ꢁ–176.9(5)ꢁ, and
P–Ni–C close to 90ꢁ. The Ni–C(1) and C(1)„C(2) dis-
tances each lie within a very narrow range and are equal
within experimental error at 1.830(6)–1.865(6) and
˚
1.204(4)–1.213(3) A, respectively. They are comparable
to those found for other compounds of this type

P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
4551
Molecule A
Molecule B
Fig. 2. The structure and atom labelling of Ni(g5-C5H5)(PPh3)–C„C–Fc (1j).
C–C bonds, C(20)–C(24)/C(22)–C(23), and one particu-
larly short Ni–Cring bond to C(21). The bond distances
and angles within the phenanthryl group are normal.
There are two molecules (A and B) in the asymmetric
unit of {Ni(g5-C5H5)(PPh3)–C„C–C5H4}Fe(g5-C5H5),
1j, which differ slightly in geometry. Molecule A, has
its Ni-bound cyclopentadienyl ligand disordered over
two sites. In the non-disordered molecule B the Ni-coor-
dinated cyclopentadienyl ligand adopts the same orien-
tation with respect to the P–Ni–C plane as it does in
the phenanthryl derivative 1e, but there is no marked
distortion of the C5H5. However, although the struc-
tures of 1e and 1j are similar, in the phenanthryl deriv-
ative the angle between the planar endgroup and the
P–Ni–C(1) plane is 12.1ꢁ, in the ferrocenyl derivative it
is 50.1ꢁ and 60.1ꢁ for isomers A and B, respectively. Fur-
thermore the P–Ni–C(1) angles of 86.77(17)ꢁ and
85.97(17)ꢁ in 1j are very low compared with those of
other Ni(g5-C5H5)(PPh3)–C„C–X complexes. In 1j
˚
the Fe–C(C5H4), 2.031(6)–2.047(6) A, show much
greater variation than the Fe–C(C5H5), 2.021(7)–
˚
2.025(7) A, but both are shorter than the Ni–C(C5H5)
˚
distances, 2.083–2.134(6) A (values quoted are for mole-
cule B) which are normal.
3.2. Spectra of Ni(g5-C5H5)(PPh3)–CC–Ar (1)
The m(C„C) vibrations of 1 give rise to weak but
readily identifiable IR absorption bands. Their frequen-
cies are a function of Ar, and decrease along the series

4552
P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
C5
C4
C3
C6
C7
Ni
C1
C2
P
C9
C20
C8
C14
C15
C21
Fig. 3. The structure and atom labelling of Ni(g5-C5H5)(PPh3)–C„C–H (1l).
Ar = ferrocenyl (2102 cmꢁ1) > C6H5 > 4-PhC6H4 > 2-
naphthyl ꢀ 9-phenanthryl > 2-thienyl > 1-naphthyl > 3-
pyrenyl ꢀ 1-perylenyl > 9-anthryl (2075 cmꢁ1). As the
m(C„C) frequencies are 2110–2115 cmꢁ1 for all
ArC„CH, and 1959 cmꢁ1 for Ni(g5-C5H5)(PPh3)–
C„C–H, 1l, it appears that the C„C in 1a–j are more
like those in ArC„CH than that in Ni(g5-
C5H5)(PPh3)–C„C–H. The IR spectrum of Ni(g5-
C5H5)(PPh3)–C„C–H shows an absorption band at
3276 cmꢁ1 which is absent from the spectra of other 1
and is attributed to m(CC–H).
which is similar to that for m(C„C). The chemical shifts
for Ni(g5-C5H5)(PPh3)–C„C–H and Ni(g5-C5H5)
(PPh3)–C„C–SiMe3 occur at extremes of 80.8 and
110.6 d, respectively. The resonances for C(2) are all
found downfield from those due to C(1) (110.7–120.2
d) and become increasingly deshielded for Ar = 2-naph-
thyl > 3-pyrenyl > C6H5 ꢀ 4-PhC6H4 > 1-perylenyl > 1-
naphthyl ꢀ 9-phenanthryl > 9-anthryl, compared with
105.5 d for Ni(g5-C5H5)(PPh3)–C„C–H.
The UV–Vis spectrum of 1a shows an intense absorp-
tion band at 271 nm (e = 19000 dm3 molꢁ1 cmꢁ1) which
tails into the visible region. Embedded in this tail is a
1
The H NMR spectra of 1 show a singlet due to the
g5-C5H5 group and numerous resonances due to the
Ph3P ligand and Ar groups which could not always be
separated and assigned individually. Unlike the other
compounds, the spectrum of Ni(g5-C5H5)(PPh3)–
C„C–H shows a doublet at d 1.47 (J = 2.4 Hz) due to
the 31P coupled acetylenic proton, and that of Ni(g5-
C5H5)(PPh3)–C„C–SiMe3 shows a singlet at d ꢁ0.39
due to the SiMe3 group. In the 13C NMR spectra the
resonances due to Ph3P and Ar groups also overlap
whilst the g5-C5H5 ligand gives rise to a singlet or a dou-
blet due to limited coupling to 31P (J = 2.2 Hz). The
resonances due to C(1) and C(2) of the alkynyl group
are weak; the former is a readily identified doublet
(J = ca. 49 Hz) due to coupling to 31P, but the latter is
usually a singlet and cannot always be found. The chem-
ical shifts for C(1) are found in the range 86.2–99.3
d and are increasingly deshielded for Ar = C6H5 >
4-PhC6H4 > 2-naphthyl > 1-naphthyl > 9-phenanthryl >
2-thienyl > 3-pyrenyl ꢀ 1-perylenyl > 9-anthryl, a series
much weaker band (e = 1210 dm3 molꢁ1 cmꢁ1
) at
422 nm. As a comparable band is also present in the
spectrum of Ni(g5-C5H5)(PPh3)–C„C–H (417 nm,
e = 1060 dm3 molꢁ1 cmꢁ1), we attribute this weak band
to an electronic transitions within the Ni(g5-
C5H5)(PPh3)–C„C moiety. It can be seen in the spectra
of other derivatives of 1, but not when Ar = 9-anthryl,
3-pyrenyl and 3-perylenyl. As the annellation of the Ar
end-group increases, absorption bands due to electronic
transitions of the aryl group move to lower energies, be-
come more intense and swamp the ca. 420 nm band.
Consequently 1i is red-orange in colour whilst the other
1 are varying shades of green. Previous experience [5]
suggests that the ‘‘aromatic’’ bands correspond to the
substituent-sensitive p bands of the parent hydrocarbon,
ArH. These shift to longer wavelengths in going from
ArH to ArCCH, and lose their vibrational fine structure
if there is significant conjugation into the substituents
[24]. In 1f–h these ‘‘aromatic’’ bands are found at longer

P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
4553
Table 2
Selected bond lengths (A) and bond angles (ꢁ) for 1f, 1j (molecule A and molecule B) and 1l
˚
Ni(g-C5H5)(PPh3)–C„C–
C14H9 (1f) (C10H7 = 9-
phenanthryl)
Ni(g5-C5H5)(PPh3)–C„C–C5H4Fe(g5-C5H5), 1j
Ni(g5-C5H5)(PPh3)–C„C–H,
1l
Molecule A Molecule B
Coordination about Ni
Ni(1)–P(2)
Ni(1)–C(1)
2.1453(8) Ni(1)–P(1)
2.1303(17) Ni(2)–P(2)
2.1272(16) Ni–P
2.1494(13)
1.850(5)
2.088(5)
2.141(5)
2.128(5)
2.086(5)
2.152(5)
1.438(8)
1.385(8)
1.427(8)
1.412(8)
1.420(7)
90.29(15)
1.858(8)
2.131(3)
2.072 (3)
2.165(3)
2.110(3)
2.107(3)
1.438(4)
1.385(4)
1.418(4)
1.425(4)
1.384(5)
92.44(8)
Ni(1A)–C(1)
1.865(6)
2.112(16)
2.08(2)
2.05(3)
2.15(3)
2.15 (2)
1.42(3)
1.36(2)
1.43(5)
1.44(3)
1.42(2)
86.77(17)
Ni(2)–C(1B)
1.830(6)
2.093(6)
2.134(6)
2.083(6)
2.122(6)
2.132(6)
1.386(8)
1.393(8)
1.399(8)
1.385(8)
1.413(8)
85.97(17)
Ni–C(1)
Ni(1)–C(20)
Ni(1)–C(21)
Ni(1)–C(22)
Ni(1)–C(23)
Ni(1)–C(24)
C(20)–C(21)
C(21)–C(22)
C(22)–C(23)
C(23)–C(24)
C(20)–C(24)
P(2)–Ni(1)–C(1)
Ni(1)–C(11A)
Ni(1)–C(12A)
Ni(1)–C(13A)
Ni(1)–C(14A)
Ni(1)–C(15A)
C(11A)–C(12A)
C(12A)–C(13A)
C(13A)–C(14A)
C(14A)–C(15A)
C(11A)–C(15A)
P(1)–Ni(1)–C(1A)
Ni(2)–C(11B)
Ni(2)–C(12B)
Ni(2)–C(13B)
Ni(2)–C(14B)
Ni(2)–C(15B)
C(11B)–C(12B)
C(12B)–C(13B)
C(13B)–C(14B)
C(14B)–C(15B)
C(11B)–C(15B)
P(2)–Ni(2)–C(1B)
Ni(1)–C(3)
Ni(1)–C(4)
Ni(1)–C(5)
Ni(1)–C(6)
Ni(1)–C(7)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(3)–C(7)
P–Ni–C(1)
Within the Ni–C„C moiety
Ni(1)–C(1)
C(1)–C(2)
C(2)–C(3)
Ni(1)–C(1)–C(2) 174.0(2)
C(1)–C(2)–C(3) 179.0(3)
1.858(3)
1.213(3)
1.449(3)
Ni(2)–C(1A)
C(1B)–C(2A)
C(2B)–C(51A)
Ni(2)–C(1A)–C(2A)
C(1B)–C(2A)–C(51A) 172.9(6)
1.865(6)
1.206(7)
1.435(8)
175.2(5)
Ni(2)–C(1B)
C(1B)–C(2B)
C(2B)–C(51B)
Ni(2)–C(1B)–C(2B)
C(1B)–C(2B)–C(51B) 175.7(6)
1.830(6)
1.210(7)
1.442(7)
175.8(6)
Ni–C(1)
C(1)–C(2)
1.850(5)
1.203(7)
Ni–C(1)–C(2)
176.9(5)
Within the Ar moiety
C(3)–C(4)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(5)–C(10)
C(10)–C(11)
C(11)–(C16)
C(11)–C(12)
C(12)–C(13)
C(13)–C(14)
C(14)–C(15)
C(15)–C(16)
1.365(3)
1.448(3)
1.435(3)
1.414(3)
1.369(4)
1.399(4)
1.377(4)
1.420(3)
1.424(3)
1.456(3)
1.428(3)
1.410(3)
1.368 (4)
1.399(4)
1.379(4)
1.417(3)
Fe(1)–C(51A)
Fe(1)–C(52A)
Fe(1)–C(53A)
Fe(1)–C(54A)
Fe(1)–C(55A)
C(51A)–C(52A)
C(52A)–C(53A)
C(53A)–C(54A)
C(54A)–C(55A)
C(51A)–C(55A)
Fe(1)–C(61A)
Fe(1)–C(62A)
Fe(1)–C(63A)
Fe(1)–C(64A)
Fe(1)–C(65A)
C(61A)–C(62A)
C(62A)–C(63A)
C(63A)–C(64A)
C(64A)–C(65A)
C(61A)–C(65A)
2.053(6)
Fe(2)–C(51B)
Fe(2)–C(52B)
Fe(2)–C(53B)
Fe(2)–C(54B)
Fe(2)–C(55B)
C(51B)–C(52B)
C(52B)–C(53B)
C(53B)–C(54B)
C(54B)–C(55B)
C(51B)–C(55B)
Fe(2)–C(61B)
Fe(2)–C(62B)
Fe(2)–C(63B)
Fe(2)–C(64B)
Fe(2)–C(65B)
C(61B)–C(62B)
C(62B)–C(63B)
C(63B)–C(64B)
C(64B)–C(65B)
C(61B)–C(65B)
2.047(6)
2.030(5)
2.018(6)
2.031(6)
2.031(6)
1.404(7)
1.405(7)
1.396(7)
1.411(7)
1.419(7)
2.047(6)
2.024(7)
2.042(6)
2.031(6)
2.019(7)
1.412(9)
1.386(9)
1.390(9)
1.394(8)
1.408(9)
2.031(6)
2.083(6)
2.034(6)
2.034(6)
1.418(7)
1.406(7)
1.415(8)
1.403(7)
1.422(7)
2.047(6)
2.024(7)
2.021(7)
2.021(7)
2.024(6)
1.398(10)
1.404(9)
1.386(9)
1.386(8)
1.388(9)
wavelengths than for ArH [25]. They also have vibra-
tional structures which are similar those observed for
ArH though not as well-defined nor identical in appear-
ance, particularly when Ar = 9-anthryl. This suggests
that resonance interaction between Ar and Ni is limited.
The typical absorption bands for a ferrocenyl group
expected for 1j, are swamped by the Ni(g5-C5H5)
(PPh3)–C„C absorptions. It should be noted that the
UV–Vis spectra of 1 are independent of solvent.
but for the acene or phene complexes 1a–1i Eap lie in the
range 0.76–0.81 V (Table 3). We note that in Ni(g5-
C5H5)(PPh3)–C„C–X derivatives the oxidation poten-
tial increases with increasing acceptor capability of X;
for example, Eap ¼ 0.98 V when X = CHO. This suggests
that the aromatic end-groups Ar are acting as donors
and, as the potential Eap decreases slightly for
1g < 1f < 1h, that the larger polycyclic aromatic groups
pyrenyl, anthryl and perylenyl are better donors than
the smaller ones. Consequently, the HOMO for the pri-
mary oxidation must have a contribution from the acet-
ylide and Ni(g5-C5H5) moieties, a conclusion also
reached by Humphries et al. [3]. In the electrochemistry
of 1j the reversible ferrocenyl couple precedes A and the
equal currents for these two couple confirms that the
3.3. Electrochemistry of Ni(g5-C5H5)(PPh3)–CBC–Ar
(1)
1 undergo a primary one electron oxidation process A
(Fig. 4). For Ni(g5-C5H5)(PPh3)–C„C–H, Eap ¼ 0.83 V,

4554
P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
Fig. 4. Full CV of Ni(g5-C5H5)(PPh3)–C„C–C6H5 (CH2Cl2/ TBAPF6)
500 mV sꢁ1
.
Fig. 5. CV of Ni(g5-C5H5)(PPh3)–C„C–C16H9, 200 mV sꢁ1: (------)
CH2Cl2; (—–) MeCN.
Table 3
Cyclic voltammetry for Ni(g5-C5H5)(PPh3)–C„C–Ar (1)
solvent. There are no reduction waves in the cyclic
voltammetry of 1a–1h, other than that associated with
A, providing the anodic potential does not exceed
0.95 V.
a
Compound
Ep
(A)
ic/ia
0.7
Ni(g5-C5H5)(PPh3)–C„C–C6H5 (1a)
0.81
0.81
0.81
0.81
Ni(g5-C5H5)(PPh3)–C„C–C6H4Ph-4 (1b)
Ni(g5-C5H5)(PPh3)–C„C–C10H7 (1-naphthyl) (1c)
Ni(g5-C5H5)(PPh3)–C„C–C10H7 (2-naphthyl) (1d)
0.5
1.0
1.0
0.3
1.0
1.0
1.0
1.0
0.8
If the anodic scan range in CH2Cl2 is extended,
another oxidation process B appears at Eap 1.2–1.5 V.
On cathodic scans after B two new reduction processes
are seen; C at Ecp ꢀ ꢁ0.08 V and D at ꢁ0.80 V
(Fig. 4). B and C are identical to the redox parameters
of free Ph3P [26]. In agreement with this assignment,
the electrochemical parameters of B and D are indepen-
dent of solvent and of the acetylide substituent. Thus, at
least in part, the current of B is due to uncoordinated
Ph3P. Our caution here is because the oxidation poten-
tials for ArC„CH and the irreversible oxidation of
[Ni(g5-C5H5)(PPh3)2]+, a known reaction product of
Ni(g5-C5H5)(PPh3)X derivatives, both occur in the
region of 1.25–1.5 V [27]. D has a current ratio of
i(D)/i(A) between <0.1 and 0.9 depending on the solvent
and acetylide substituent. Its current has no relationship
to that of B or the chemical reversibility of A. Electro-
chemical profiles are similar on repeat scans. To further
investigate whether ligand loss from the Ni(III) species
was a component of the chemical irreversibility, the elec-
trochemistry was repeated in the presence of CO and
PPh3. CO had no effect. Unexpectedly, the addition of
PPh3 caused A to be completely irreversible in both
CH2Cl2 and CH3CN between 50 mV sꢁ1 and 2 V sꢁ1
for all complexes (Fig. 6). Features B and C are rein-
forced and D unaffected, as expected if the assignments
are correct.
Ni(g5-C5H5)(PPh3)–C„C–C14H9 (9-phenanthryl) (1e) 0.81
Ni(g5-C5H5)(PPh3)–C„C–C14H9 (9-anthryl) (1f)
Ni(g5-C5H5)(PPh3)–C„C–C16H9 (3-pyrenyl) (1g)
Ni(g5-C5H5)(PPh3)–C„C–C20H11 (3-perylenyl) (1h)
Ni(g5-C5H5)(PPh3)–C„C–C4H3S-2 (2-thienyl) (1i)
Ni(g5-C5H5)(PPh3)–C„C–C10H9Fe+ (ferricenium)
(1j+)
0.77
0.79
0.76
0.80
1.03b
Ni(g5-C5H5)(PPh3)–C„C–H (1l)
Ni(g5-C5H5)(PPh3)–C„C–CHO [1]
a
0.83
1.04
<0.1
<0.1
Eap (A) (200 mV sꢁ1); ic/ia(1500 mV sꢁ1); (CH2Cl2, TBAPF60.1 M,
Pt electrode, internal Fc* reference).
b
E0 [Ferrocenyl+/0] for this compound is 0.41 V.
primary process A is a one-electron transfer. E0[Fc+/0] =
0.41 V for this couple, compared to E0[Fc+/0] = 0.72 V
for FcC„CH, shows that the (g-C5H5)Ni entity is
acting as a strong donor with respect to the ferricenium
acetylide substituent. The positive charge on 1j+ increa-
ses Eap to 1.03 V.
A striking feature of the electrochemistry of 1 is the
variation in the chemical reversibility of A as a function
of scan rate and solvent, as well as alkyne substituent.
For 1a in CH2Cl2 for example: at scan rates
<100 mV sꢁ1, ic/ia = 0.1; at 100–400 mV sꢁ1, ic/ia =
0.5; at 2 V sꢁ1, ic/ia = 1, that is, chemically reversible.
The companion cathodic feature occurs at Ecp ¼
0.68 V. In CH3CN, however, no companion cathodic
feature is observed up to 5 V sꢁ1, and in the temperature
range 295–193 K. Similar behaviour is observed for the
ferrocenyl complex 1j+ and the complexes with polycy-
clic aromatic acetylide substituents 1b–1i (Fig. 5). These
data are consistent with a primary oxidation of 1 to give
a Ni(III) species at Eap ðAÞ followed by a rapid chemical
reaction which is influenced by the donor ability of the
It is clear that stability of the 17e Ni(III) species de-
pends on the type of acetylide substituents with the most
stable being those with p-donor substituents, and that
the formation of this species leads to the rapid loss of
PPh3 and a decomposition reaction. A seemingly contra-
dictory observation is that the addition of PPh3 or a
donor solvent assists this instability. Unfortunately, IR
and UV–Vis OTTLE studies, or chemical oxidation with
the aminium salt ÔMagic BlueÕ, did not give further

P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
4555
3.4. Spectraof{Ni(g5-C5H5)(PPh3)–CBC–Ar}Co2(CO)6
(2)
The IR spectra of 2 in dichloromethane solution
show three absorption bands due to the m(CO) vibra-
tions of the Co2(CO)6 moiety with the broad band at
lowest frequency having more than one component (cf.
[30]). Their relative intensities are comparable to those
of other (alkyne)Co2(CO)6 compounds, but their fre-
quencies are much lower {cf. (3-pyrenyl–C„C–H)
Co2(CO)6, m(CO) = 2090, 2054, 2025 cmꢁ1; (2-thienyl–
C„C–H)Co2(CO)6, m(CO) = 2094, 2058, 2028 cmꢁ1
;
(Ph–C„C–Ph)Co2(CO)6, m(CO) = 2091, 2055, 2026
cmꢁ1}. This is attributed to the strong donor capabilities
of the (g5-C5H5)(PPh3)Ni substituents which leads to a
considerable increase in the electron-richness of the
C2Co2 moiety and a decrease of ca. 30 cmꢁ1 of the
m(CO) frequencies as has been discussed elsewhere [1].
In a second, less marked, effect the m(CO) frequencies
of 2 are lower for the larger Ar groups than for the smal-
ler, which further suggests that the former are better do-
nors to the dicobaltatetrahedrane moiety than are the
latter. The donor capabilities of acetylene substituents
in (RCCR0)Co2(CO)6 complexes is evident in the de-
crease of their m(CO) frequencies along the series
R,R0 = H,H > Ph,H > Ph,Ph > Ph,Ni(g5-C5H5)(PPh3).
Fig. 6. CV of Ni(g5-C5H5)(PPh3)–C„C–C16H9: (-----) 200 mV sꢁ1
ꢁ45 ꢁC; (——) after addition of PPh3.
/
insight into the EC mechanism. There is no electrochem-
ical evidence for a disproportionation of Ni(III) to
Ni(IV) and Ni(II) (a common route for decomposition
of Ni(I) complexes) [28]. Furthermore, Ni(g5-C5H5)2 is
not produced and there is no other electroactive species
linked to A apart from PPh3. Explanations which satisfy
the data are that dimerisation or a g5 ! g1 (or g3)
transformation takes place upon formation of the 17e
species.
The UV spectrum of 1j+ generated in the OTTLE cell
was recorded and is illustrated in Fig. 7. The significant
feature is the low energy transition at 1550 nm. Bands
such as this are found in the spectra of most Fc¯–
C„CR species and are assigned to an LMCT from a
donor orbital on R to the ferrocenium LUMO [5]. The
energy of this transition for 1j+ is lower than those for
most Fc¯C„CAr [5] and is similar to the IVCT band re-
corded for Fe(g5-C5H5)(Ph2PCH2CH2PPh2)–C„C–
Fc¯ at 1590 nm [29]. Clearly, Ni(g5-C5H5)(PPh3) is
functioning as a strong donor to the ferrocenium end-
group through the p linkage.
4. Conclusions
Spectroscopic and electrochemical evidence suggests
that in Ni(g5-C5H5)(PPh3)–C„C–Ar complexes 1 com-
munication between the Ni(g5-C5H5)(PPh3) group and
the Ar groups is limited, at least in the ground state,
and is not sufficient to bring about any significant
changes in the dimensions of the Ni–C„C–Ar moiety
as determined by X-ray diffraction. However, there is
a lowering of the m(C„C) frequencies of 1, as compared
with Ar–C„C–H, and changes in the d(13C) chemical
shifts for Ni–C„C, which increase in importance as
the annelation of Ar increases but are always limited.
These and other spectroscopic data suggest that it is un-
likely that any 1 would exhibit significant second order
NLO activity, as has been confirmed by others [3].
The frequencies of the m(CO) bands of the {Ni(g5-
C5H5)(PPh3)–C„C–Ar}{Co2(CO)6} complexes 2, de-
rived from 1, confirm that the Ni(g5-C5H5)(PPh3)
moiety is a powerful electron-donor but also indicate
that the aryl group Ar are weaker donors. This is consis-
tent with the electrochemical data.
295
1
.8
.6
.4
554
405
1550
.2
0
400
600
800
1000
1200
1400
1600
Nanometers
5. Supplementary material
Fig. 7. The electronic spectrum of [Ni(g5-C5H5)(PPh3)–C„C–Fc]+,
[1j]+, generated in the OTTLE cell on electrochemical oxidation of
[Ni(g5-C5H5)(PPh3)–C„C–Fc] ([1j]).
Crystallographic data for the structural analyses have
been deposited at the Cambridge Crystallographic Data

4556
P. Butler et al. / Journal of Organometallic Chemistry 690 (2005) 4545–4556
[8] K. Sonogashira, T. Yatake, Y. Tohoda, S. Takahashi, N.
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Hagihara, J. Organomet. Chem. 6 (1966) 86.
[10] Enraf-Nonius. CAD4-PC Software, Version 1.1. Enraf-Nonius,
Delft, The Netherlands, 1992.
Centre, CCDC Nos. CCDC 269736 (1e), CCDC 271151
(1j) and CCDC 270147 (1l). Copies of the information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ (fax:
+44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk or
http://www.ccdc.cam.ac.uk)
[11] SMART CCD Software, Bruker AXS, Madison WI, USA, 1994.
[12] SADABS Bruker AXS, Madison WI, 1997.
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Acknowledgements
J.F.G. thanks Professor George Ferguson for the use
of the diffractometer and computer system in the collec-
tion of the dataset for 1j. J.S. thanks Professor Ward
Robinson (University of Canterbury) for collecting the
data for 1e. P.B. thanks Enterprise Ireland and Scher-
ing-Plough (Avondale) for financial support.
[20] J.F. Gallagher, P. Butler, A.R. Manning, Acta Cryst. C 54 (1998)
342.
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