The reactions of some σ-alkynylnickel complexes with 7,7,8,8-tetracyanoquinodimethane

Article abstract of DOI:10.1016/j.jorganchem.2007.11.029

The σ-alkynyl complexes Ni(η⁵-C₅H₅)(PPh₃)-C{triple bond, long}C-R (1), Ni(η⁵-C₅H₅)(PPh₃)-C{triple bond, long}C-X-C{triple bond, long}CH (2) and Ni(η⁵-C₅H₅)(PPh₃)-C{triple bond, long}C-X-C{triple bond, long}C-Ni(η⁵-C₅H₅)(PPh₃) (3), reactwith 7,7,8,8-tetracyanoquinodimethane, TCNQ, at 30 °C by insertion of the alkyne C{triple bond, long}C into a C{double bond, long}C(CN)₂ bond to give Ni(η⁵-C₅H₅)(PPh₃)-C{{double bond, long}C₆H₄{double bond, long}C(CN)₂}-C{{double bond, long}C(CN)₂}-R (4), from 1, Ni(η⁵-C₅H₅)(PPh₃)-C{{double bond, long}C₆H₄{double bond, long}C(CN)₂}-C{{double bond, long}C(CN)₂}-X-C{triple bond, long}CH (5), from 2, and Ni(η⁵-C₅H₅)(PPh₃)-C{{double bond, long}C₆H₄{double bond, long}C(CN)₂}-C{{double bond, long}C(CN)₂}-X-C{triple bond, long}C-Ni(η⁵-C₅H₅)(PPh₃) (6),and Ni(η⁵-C₅H₅)(PPh₃)-C{{double bond, long}C₆H₄{double bond, long}C(CN)₂}- C{{double bond, long}C(CN)₂}-X-C{{double bond, long}C(CN)₂}-C{{double bond, long}C₆H₄{double bond, long}C(CN)₂}-Ni(η⁵-C₅H₅)(PPh₃) (7),from 3 {R = (a) C₆H₅, (b) 4-PhC₆H₄, (c) 4-Me₂NC₆H₄, (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), (j) 2-C₄H₃S (2-thienyl), (k) C₁₀H₉Fe (ferrocenyl = Fc) and (l) H; X = (a) nothing, (b) 1,4-C₆H₄, (c) 1,3-C₆H₄ and (d) 4,4′-C₆H₄-C₆H₄}. The reaction is regiospecificand the other possible insertion product, R-C{{double bond, long}C₆H₄{double bond, long}C(CN)₂}-C{{double bond, long}C(CN)₂}-Ni(η⁵-C₅H₅)(PPh₃) etc., is not formed. Under the same conditions, there is no evidencefor the reaction of TCNQ with the -C{triple bond, long}CH of 2, PhC{triple bond, long}CH, 1,4-C₆H₄(C{triple bond, long}CH)₂ or FcC{triple bond, long}CH, or for the reaction of more than one C{double bond, long}C(CN)₂ of TCNQ with a Ni-alkynyl moiety. Complexes 4-7 are all air-stable, purple solids which have been characterised by elemental analysis and spectroscopy (IR, UV-Vis, ¹H NMR and ¹³C NMR),and by X-ray diffraction for 4a, 4b and 4l. The UV-Vis spectra of 4-7 are very similar. This implies that all contain the same active chromophore which, it is suggested, is Ni-C(5){double bond, long}C₆H₄{double bond, long}C(CN)₂ and not R-C(4){double bond, long}C(CN)₂. This isconsistent with the molecular structures of 4a, 4b and 4l which show that the first of these potentially chromophoric fragments is planar or close to it with an in-built potential for delocalisation, whilst in the second the aryl group R is almost orthogonal to the C{double bond, long}C(CN)₂ plane. The molecular structures of 4a, 4b and 4l also reveal a short Ni?C(4) separation, indicative of a Ni → C(4) donor-acceptor interaction. The electrochemistry of 4a shows aquasi reversible oxidation at ca. 1 V and complicated reduction processes. It is typical of most 4, but 4l is different in that it shows the same quasi reversible oxidation at ca. 1 V but two reversible reductions at -0.26 and -0.47 V (vs. [Fe(η⁵-C₅Me₅)₂]^+/0 0.0 V).

Full text of DOI:10.1016/j.jorganchem.2007.11.029

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 381–392
www.elsevier.com/locate/jorganchem
The reactions of some r-alkynylnickel complexes
with 7,7,8,8-tetracyanoquinodimethane
a
a,
b
b
*
Peter Butler , Anthony R. Manning , C. John McAdam , Jim Simpson
a Department of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
b Department of Chemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
Received 15 September 2007; received in revised form 30 October 2007; accepted 6 November 2007
Available online 22 November 2007
Abstract
The r-alkynyl complexes Ni(g5-C5H5)(PPh3)–C„C–R (1), Ni(g5-C5H5)(PPh3)–C„C–X–C„CH (2) and Ni(g5-C5H5)(PPh3)–
C„C–X–C„C–Ni(g5-C5H5)(PPh3) (3), reactwith 7,7,8,8-tetracyanoquinodimethane, TCNQ, at 30 °C by insertion of the alkyne
C„C into a C@C(CN)2 bond to give Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–R (4), from 1, Ni(g5-C5H5)(PPh3)–
C{@C6H4@C(CN)2}–C{@C(CN)2}–X–C„CH (5), from 2, and Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–X–C„C–
Ni(g5-C5H5)(PPh3) (6),and Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}– C{@C(CN)2}–X–C{@C(CN)2}–C{@C6H4@C(CN)2}–Ni(g5-
C5H5)(PPh3) (7),from 3 {R = (a) C6H5, (b) 4-PhC6H4, (c) 4-Me2NC6H4, (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), (j) 2-C4H3S (2-thienyl), (k)
C10H9Fe (ferrocenyl = Fc) and (l) H; X = (a) nothing, (b) 1,4-C6H4, (c) 1,3-C6H4 and (d) 4,40-C6H4–C6H4}. The reaction is regio-
specificand the other possible insertion product, R–C{@C6H4@C(CN)2}–C{@C(CN)2}–Ni(g5-C5H5)(PPh3) etc., is not formed.
Under the same conditions, there is no evidencefor the reaction of TCNQ with the –C„CH of 2, PhC„CH, 1,4-C6H4(C„CH)2
or FcC„CH, or for the reaction of more than one C@C(CN)2 of TCNQ with a Ni-alkynyl moiety. Complexes 4–7 are all air-sta-
1
ble, purple solids which have been characterised by elemental analysis and spectroscopy (IR, UV–Vis, H NMR and 13C NMR),and
by X-ray diffraction for 4a, 4b and 4l. The UV–Vis spectra of 4–7 are very similar. This implies that all contain the same active
chromophore which, it is suggested, is Ni–C(5)@C6H4@C(CN)2 and not R–C(4)@C(CN)2. This isconsistent with the molecular
structures of 4a, 4b and 4l which show that the first of these potentially chromophoric fragments is planar or close to it with
an in-built potential for delocalisation, whilst in the second the aryl group R is almost orthogonal to the C@C(CN)2 plane. The
molecular structures of 4a, 4b and 4l also reveal a short Niꢀ ꢀ ꢀC(4) separation, indicative of a Ni ? C(4) donor–acceptor interaction.
The electrochemistry of 4ashows aquasi reversible oxidation at ca. 1 V and complicated reduction processes. It is typical of most 4,
but 4l is different in that it shows the same quasi reversible oxidation at ca. 1 V but two reversible reductions at ꢁ0.26 and ꢁ0.47 V
(vs. [Fe(g5-C5Me5)2]+/0 0.0 V).
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Ni; Alkyne; TCNQ; Insertion
1. Introduction
cyclobutenyls which may subsequently isomerise to buta-
1,3-dienyl complexes, (NC)2C@C(M)–C(R)@C(CN)2 so
the overall reaction is the insertion of the CC triple bond
into the double bond of TCNE [1–11]. Other activated ole-
fins react similarly [12]; in particular there has been a single
report on the use of 7,7,8,8-tetracyanoquinodimethane,
TCNQ, in this role. With trans-Pt(PMe3)2(C„C–Me)2 it
gives trans-Pt(PMe3)2(CCMe)C{C6H4C(CN)2}C{CC(CN)2}
Me [13,14].
The reactions of C2(CN)4, TCNE, with metalloalkynes
MC„CR have been extensively investigated. They give
*
Corresponding author. Tel.: +353 1 7062495; fax: +353 1 7062127.
E-mail addresses: Anthony.Manning@ucd.ie (A.R. Manning),
Jsimpson@alkali.otago.ac.nz (J. Simpson).
0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.11.029

382
P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
Herein we report on further reactions of TCNQ with
methane (30 mL). There was an immediate colour change
from green or orange to red/purple. After 15 min the reac-
tion mixture was chromatographed on silica using dichlo-
romethane to elute the product in good yield. Removal
of the solvent and recrystallisation of the residue from ace-
tonitrile–ether mixtures gave dark crystals of Ni(g5-
C5H5)(PPh3)–C{@C6H4@C(CN)2]}–C{@C(CN)2}–R (4a–
l) where R = (a) C6H5, (b) 4-PhC6H4, (c) 4-Me2NC6H4,
(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), (j) 2-C4H3S
(2-thienyl), (k) C10H9Fe (ferrocenyl) and (l) H.
metalloalkynes, particularly those containing a Ni(g5-
C5H5)(PPh3) substituent. We had hoped that the reactions
would give Ni(g5-C5H5)(PPh3)–C„C–R/TCNQ charge
transfer complexes similar to those obtained from (g5-
C5H5)Fe(g5-C5H4CH@CH–aryl) and TCNQ [15,16] and
expected these to be more stable for the more highly ann-
elated aryl groups. In the event, this did not happen and
all reactions gave insertion products similar to those
described above.
2. Experimental
There was no reaction between TCNQ and 1,4-diethyn-
ylbenzene, phenylacetylene or ferrocenyl acetylene even
after 2 h at 30 °C.
2.1. General procedures
Published procedures or extensions thereof were used to
prepare Ni(g5-C5H5)(PPh3)Br [17], RC„CH [18,19],
HC„C–C„CH [20], 1,3-C6H4(C„CH)2 [21], 1,4-
C6H4(C„CH)2 [21], and 4,40-HC„C–C6H4–C6H4–C„CH
[20]. Ni(g5-C5H5)(PPh3)–C„C–R (1), Ni(g5-C5H5)(PPh3)–
C„C–X–C„CH (2) and Ni(g5-C5H5)(PPh3)–C„C–X–
C„C–Ni(g5-C5H5)(PPh3) (3), {R = Ph, 4-PhC6H4,
4-Me2NC6H4, 1-C10H7 (1-naphthyl), 2-C10H7 (2-naphthyl),
9-C14H9 (9-phenanthryl), 9-C14H9 (9-anthryl), 3-C16H9
(3-pyrenyl), 1-C20H11 (1-perylenyl), 2-C4H3S (2-thienyl),
C10H9Fe (ferrocenyl)} and H [22–24]. Other chemicals were
purchased and used as received.
2.2.1. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C6H5 (4a)
Anal. Calc. for C43H29N4NiP: C, 74.7; H, 4.2; N, 8.1.
Found: C, 74.6; H, 4.2; N, 8.0%. IR m/cmꢁ1: m(C„N)
1
2212 (CH2Cl2); m(C„N) 2213 (KBr). H NMR (CDCl3):
d 8.19 [1H, br, C6H4], 6.7–7.7 [24H, m, C6H4, C6H5 and
PPh3], 5.34 [5H, s, C5H5]. 13C NMR (CDCl3): d 203.1
(br), 184.5 (br), 156.2, 144.2, 143.2, 134.7, 133.6, 131.2,
130.9, 129.4, 128.8, 128.6, 127.6, 123.7, 120.3, 115.0,
114.8, 113.4, 113.3, 95.8, 73.6, 69.3.
kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 478 (18,400), 571 (sh, 8,000) in
Unless it is stated otherwise, all reactions were carried
out at room temperature in the dark under an atmosphere
of nitrogen in dried and deoxygenated solvents. They were
monitored by IR spectroscopy when necessary.
CH2Cl2; 472 (17100), 570 (sh, 8100) in CH3CN.
2.2.2. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C6H4–C6H5-4 (4b)
Infrared spectra were recorded on a Perkin–Elmer Par-
agon 1000 FTIR Spectrometer. UV–Vis spectra were
recorded on a UNICAM UV2 spectrometer. NMR spectra
were measured on a Jeol JNM-GX270 FT-NMR spec-
trometer or a Varian Unity Inova 500 MHz NMR spec-
Anal. Calc. for C49H33N4NiP: C, 76.6; H, 4.3; N, 7.3.
Found: C, 76.5; H, 4.3; N, 7.3%. IR m/cmꢁ1: m(C„N) 2223
1
(sh), 2212 (CH2Cl2); m(C„N) 2223 (sh), 2213 (KBr). H
NMR (CDCl3): d 6.61–8.49 [28H, C6H4, C6H4C6H5 and
PPh3], 5.35 [5H, s, C5H5]. 13C NMR (CDCl3): d 182.5,
155.3, 142.7, 142.1, 120.4 ꢁ135.0, 116.5, 116.2, 115.8, 95.9.
1
trometer for 4a and 4l only. H and 13C chemical shifts
are reported downfield from tetramethylsilane as internal
standard with coupling constants in Hertz. Cyclic and
square-wave voltammetry in CH2Cl2 were performed using
a three-electrode cell with a polished Pt 1 mm disk working
electrode; 10ꢁ3 M in electroactive material and 0.10 M in
supporting electrolyte (TEAP or TBAPF6). Data were
recorded on a Powerlab/4sp computer-controlled potentio-
stat. Scan rates of 0.05–1 V sꢁ1 were typically 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 refer-
enced to decamethyl ferrocene; E1/2 for sublimed ferrocene
was 0.55 V. Elemental analyses were performed in the
Microanalytical Laboratory, University College Dublin.
k
max/nm (e/dm3 molꢁ1 cmꢁ1) 477 (19400), 572 (sh, 10500)
in CH2Cl2; 475 (19000), 573 (sh, 10400) in CH3CN.
2.2.3. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C6H4N(CH3)2-4 (4c)
Anal. Calc. for C45H34N4NiP: C, 73.6; H, 4.7; N, 9.9.
Found: C, 73.7; H, 4.7; N, 9.9%. IR m/cmꢁ1: m(C„N)
1
2212 (CH2Cl2). H NMR (CDCl3): d 6.69–7.43 [23H, m,
C6H4, C6H4, PPh3], 5.33 [5H, s, C5H5], 2.90 [6H, s,
NMe2]. 13C NMR (CDCl3): d 182.5, 155.3, 142.7, 142.1,
120.4–135.0, 116.5, 116.2, 115.8, 95.9.
kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 477 (19,400), 572 (sh, 10500) in
CH2Cl2; 475 (19000), 573 (sh, 10400) in CH3CN.
2.2.4. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C10H7 (4d) (C10H7 = 1-naphthyl)
Anal. Calc. for C47H31N4NiP: C, 76.1; H, 4.2; N, 7.5.
Found: C, 76.1; H, 4.2; N, 7.5%. IR m/cmꢁ1: m(C„N) 2223
2.2. Reactions of Ni(g5-C5H5)(PPh3)–C„C–R with
tetracyanoquinodimethane (TCNQ)
1
TCNQ (0.2 g, 1.02 mmol) was added to a solution of
(sh), 2122 (CH2Cl2); m(C„N) 2223 (sh), 2113 (KBr). H
Ni(g5-C5H5)(PPh3)–C„C–R (1.02 mmol) in dichloro-
NMR (CDCl3): d 6.22–7.92 [26H, C6H4, C10H7, PPh3], 5.37

P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
383
[5H, s, C5H5]. 13C NMR (CDCl3): d 201.8 [br], 182.0, 156.2,
144.2, 143.8, 122.4–134.9, 115.0, 114.8, 113.5, 112.9, 95.9,
76.5, 70.0. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 481 (20600), 574
(sh, 10000) in CH2Cl2; 475 (21700), 574 (sh, 10000) in
CH3CN.
2222 (sh), 2122 (CH2Cl2); m(C„N) 2223 (sh), 2113 (KBr).
1H NMR (CDCl3): d 8.34 [1H, dd, J = 9.4, 1.8 Hz,
C6H4], 6.1–8.51 [28H, C6H4, C20H11, PPh3], 5.38 [5H, s,
C5H5]. 13C NMR (CDCl3): d 181.7, 153.6, 143.9, 122.3–
134.9, 116.9, 115.8, 115.2, 96.1.
kmax/nm (e/
dm3 molꢁ1 cmꢁ1) 470 (30900), 578 (sh, 9500) in CH2Cl2;
460 (30000), 578 (sh, 9400) in CH3CN.
2.2.5. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C10H7 (4e) (C10H7 = 2-naphthyl)
Anal. Calc. for C47H31N4NiP: C, 76.1; H, 4.2; N, 7.5.
Found: C, 76.1; H, 4.2; N, 7.5%. IR m/cmꢁ1: m(C„N) 2223
2.2.10. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C4H3S (4j) (C4H3S = 2-thiophenyl)
Anal. Calc. for C41H27N4NiPS: C, 70.6; H, 3.9; N, 8.0.
Found: C, 70.6; H, 3.8; N, 8.1%. IR m/cmꢁ1: m(C„N)
1
(sh), 2122 (CH2Cl2); m(C„N) 2223 (sh), 2113 (KBr). H
NMR (CDCl3): d 6.27-8.50 [26H, m, C6H4, C10H7, PPh3]
5.41 [5H, s, C5H5]. 13C NMR (CDCl3): d 183.1, 156.7,
144.1, 143.7, 121–135, 115.5, 115.4, 114.0, 113.9, 96.5, 77.3.
1
2212 (CH2Cl2); m(C„N) 2213 (KBr). H NMR (CDCl3):
d 5.81–8.43 [22H, m, C6H4, C4H3S, PPh3], 5.35 [5H, s,
C5H5]. 13C NMR (CDCl3): d 180.6, 151.2, 141.6, 116.3–
136.4 [m, C6H4, C4H3S, PPh3], 116.5, 116.2, 115.8, 95.9
[s, C5H5]. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 477 (23400), 573
(sh, 18400) in CH2Cl2; 475 (23400), 573 (sh, 18400) in
CH3CN.
k
max/nm (e/dm3 molꢁ1 cmꢁ1) 478 (28,400), 571 (sh, 9400) in
CH2Cl2; 472 (28100), 570 (sh, 9300) in CH3CN.
2.2.6. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C14H9 (4f) (C14H9 = 9-phenanthryl)
Anal. Calc. for C51H33N4NiP: C, 77.4; H, 4.2; N, 7.1.
Found: C, 77.4; H, 4.1; N, 7.0%. IR m/cmꢁ1: m(C„N)
2.2.11. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C5H4Fe(g5–C5H5) (4k)
1
2122 (CH2Cl2); m(C„N) 2113 (KBr). H NMR (CDCl3):
d 8.24 [1H, dd, J = 9.5, 1.8 Hz, C6H4], 7.22 [1H, dd,
J = 9.6, 1.8 Hz, C6H4], 7.04 [1H, dd, J = 9.8, 1.3 Hz,
C6H4], 6.97 [1H, dd, J = 9.4, 2.1 Hz, C6H4], 7.0–8.9 [9H,
m, C14H9], 6.6–7.0 [15H, m, PPh3], 5.39 [5H, s, C5H5].
13C NMR (CDCl3): d 202.1 [d, J = 23 Hz], 182.5, 155.0,
141.6, 141.1, 121 ꢁ135, 115.5, 114.1, 113.5, 96.2, 70.3.
Anal. Calc. for C47H33FeN4NiP: C, 70.6; H, 4.1; N, 7.0.
Found: C, 71.0; H, 4.1; N, 6.9%. IR m/cmꢁ1: m(C„N) 2210
1
(CH2Cl2). H NMR (CDCl3): d 8.24 [1H, d, J = 9.4 Hz,
C6H4], 7.21 [1H, d, J = 9.6 Hz, C6H4], 7.03 [1H, d,
J = 9.0 Hz, C6H4], 6.93 [1H, d, J = 9.1 Hz, C6H4], 7.3–7.8
[15H, m, PPh3], 5.21 [5H, s, C5H5(Ni)], 4.92 [5H, s,
k
max/nm (e/dm3 molꢁ1 cmꢁ1) 475 (15800), 576 (sh, 11000)
C5H5(Fe)], 4.7 and 5.2 [4H, both broad, C5H4(Fe)]. kmax/
in CH2Cl2; 475 (15700), 575 (sh, 11100) in CH3CN.
nm (e/dm3 molꢁ1 cmꢁ1) 475 (25,500), 573 (sh, 18400),
630 (10000) in CH2Cl2.
2.2.7. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C14H9 (4g) (C14H9 = 9-anthryl)
Anal. Calc. for C51H33N4NiP: C, 77.4; H, 4.2; N, 7.1.
Found: C, 77.3; H, 4.2; N, 7.1%. IR m/cmꢁ1: m(C„N)
2223 (sh), 2122 (CH2Cl2); m(C„N) 2223 (sh), 2113 (KBr).
1H NMR (CDCl3): d 6.1–9.0 [33H, C6H4, C14H9, PPh3],
5.36 [5H, s, C5H5]. 13C NMR (CDCl3): d 181.7, 154.6,
2.2.12. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–H (4l)
Anal. Calc. for C37H25N4NiP: C, 72.2; H, 4.1; N, 9.1.
Found: C, 71.9; H, 4.2; N, 9.3%. IR m/cmꢁ1: m(C„N)
2224 (sh), 2211 (CH2Cl2); m(C„N) 2226 (sh), 2209,
1
(KBr). H NMR (CDCl3): d 7.78 [1, dd, J = 9.4, 1.8 Hz,
140.9, 140.6, 122.4–134.3, 117.5, 117.2, 116.9, 96.1. kmax
/
C6H4], 7.2–7.77 [15H, m, PPh3], 7.07 [1H, s, CHC(CN)2],
7.06 [1, dd, J = 9.4, 1.8 Hz, C6H4], 6.79 [1, dd, J = 9.4,
1.3 Hz, C6H4], 6.58 [1, dd, J = 9.4, 1.3 Hz, C6H4], 5.34
[5H, s, C5H5]. 13C NMR (CDCl3): d 201.3 [C(5), d,
J = 26 Hz], 161.3 [C(4)], 156.2 [C(9)], 143.0 [C(6)], 141.7
[C(11)], 129.6 [C(7)], 124.5 [C(10)], 120.1 [C(8)], 133.4 [d,
J = 11 Hz, o Ph3P], 131.6 [s, p Ph3P], 130.1 [d, J = 49 Hz,
ipso Ph3P], 128.9 [d, J = 10.8 Hz, m Ph3P], 114.8, 114.7,
114.4, 112.7, 94.9 [s, C5H5], 70.7, 69.6 [both s, C(3)/
C(12)]. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 462 (28000), 533 (sh,
17000) in CH2Cl2; 462 (27000), 525 (sh, 19000) in CH3CN.
nm (e/dm3 molꢁ1 cmꢁ1) 484 (33000), 578 (sh, 18400) in
CH2Cl2; 478 (29000), 577 (sh, 18400) in CH3CN.
2.2.8. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C16H9 (4h) (C16H9 = 3-pyrenyl)
Anal. Calc. for C53H33N4NiP: C, 78.1; H, 4.1; N, 6.9.
Found: C, 78.0; H, 4.1; N, 6.9%. IR m/cmꢁ1: m(C„N)
1
2122 (CH2Cl2); m(C„N) 2113 (KBr). H NMR (CDCl3):
d 6.97–7.98 [35H, m, C6H4, C16H9, PPh3] 5.40 [5H, s,
C5H5]. 13C NMR (CDCl3): d 183.5, 156.8, 144.4, 121.5–
134.8, 115.6, 115.5, 114.2, 95.9 [s, C5H5]. kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 475 (23000), 576 (sh, 10300) in
CH2Cl2; 472 (22500), 577 (sh, 10200) in CH3CN.
2.3. Reactions of Ni(g5-C5H5)(PPh3)–C„C–X–C„CH
with TCNQ
2.2.9. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C20H11 (4i) (C20H11 = 3-perylenyl)
Anal. Calc. for C57H35N4NiP: C, 79.1; H, 4.1; N, 6.5.
Found: C, 79.0; H, 4.0; N, 6.4%. IR m/cmꢁ1: m(C„N)
These were carried out as above using equimolar
amounts of TCNQ (0.04 g, 0.19 mmol) and [Ni(g5-
C5H5)(PPh3)–C„C–X–C„CH]
(0.19 mmol).
Ni(g5-
C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–X–

384
P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
C„CH (5a–d) {X = (a) nothing, (b) 1,4-C6H4, (c) 1,3-
C6H4 and (d) 4,40-C6H4–C6H4}, were obtained in good
yield. They did not react further with a large excess of
TCNQ.
C5H5)(PPh3)–C„C–X–C„C–Ni(g5-C5H5)(PPh3) (0.19 mmol),
Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–
X–C„C–Ni(g5-C5H5)(PPh3) (6a–d), were obtained.
With a 2:1 molar ratio of TCNQ (0.02 g, 0.11 mmol) and
Ni(g5-C5H5)(PPh3)–C„C–X–C„C–Ni(g5-C5H5)(PPh3)
(0.055 mmol), the products were Ni(g5-C5H5)(PPh3)–
C{@C6H4@C(CN)2}–C{@C(CN)2}–X–C{@C6H4@
C(CN)2–C{@C(CN)2}–Ni(g5-C5H5)(PPh3) (7a–d).
2.3.1. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C„C–H (5a)
Anal. Calc. for C39H25NiN4P: C, 73.2; H, 3.9; N, 8.8.
Found: C, 73.1; H, 3.9; N, 8.6%. IR m/cmꢁ1: m(C„C)
2096, m(C„N) 2212, m(CC–H) 3300 (CH2Cl2); m(C„C)
2095, m(C„N) 2213, m(CC–H) 3300 (KBr). 1H NMR
(CDCl3): d 6.89–7.81 [19H, m, C6H4 and PPh3], 5.24 [5H,
2.4.1. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C„C–Ni(g5-C5H5)(PPh3) (6a)
Anal. Calc. for C62H44N4Ni2P2: C, 72.7; H, 4.3; N, 5.5.
Found: C, 72.5; H, 4.3; N, 5.4%. IR m/cmꢁ1: m(C„C) 2095,
m(C„N) 2212 (CH2Cl2); m(C„C) 2095, m(C„N) 2213
(KBr). 1H NMR (CDCl3): d 6.91–7.87 [34H, m, C6H4,
s, C5H5], 1.70 [1H, s, CC–H]. kmax/nm (e/dm3 molꢁ1 cmꢁ1
)
475 (27200), 571 (sh, 8000) in CH2Cl2; 472 (30500), 570
(sh, 8100) in CH3CN.
and PPh3], 5.23 [5H, s, C5H5], 5.22 [5H, s, C5H5]. kmax
/
2.3.2. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(1,4-C6H4)–C„C–H (5b)
nm (e/dm3 molꢁ1 cmꢁ1) 476 (32100) in CH2Cl2; 473
(34900), in CH3CN.
Anal. Calc. for C45H29N4NiP: C, 75.5; H, 4.1; N, 7.8.
Found: C, 75.4; H, 4.0; N, 7.8%. IR m/cmꢁ1: m(C„C)
2095, m(C„N) 2222 (sh), 2212, m(CC–H) 3300 (CH2Cl2);
m(C„C) 2096, m(C„N) 2223 (sh), 2213, m(CC–H) 3300
(KBr). 1H NMR (CDCl3): d 7.12–7.81 [23H, m, C6H4,
C6H4 and PPh3], 5.23 [5H, s, C5H5], 1.62 [1H, s, C„C-
H]. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 470 (32400), 562 (sh,
9800) in CH2Cl2; 471 (31700), 560 (sh, 10100) in CH3CN.
2.4.2. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(1,4-C6H4)–C„C–Ni(g5-C5H5)(PPh3)
(6b)
Anal. Calc. for C68H48N4Ni2P2: C, 74.2; H, 4.4; N, 5.1.
Found: C, 74.2; H, 4.3; N, 5.0%. IR m/cmꢁ1: m(C„C) 2092,
m(C„N) 2212 (CH2Cl2); m(C„C) 2093, m(C„N) 2213
(KBr). 1H NMR (CDCl3): d 6.85–8.05 [38H, m, C6H4,
C6H4 and PPh3], 5.26 [5H, s, C5H5], 5.24 [5H, s, C5H5].
2.3.3. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(1,3-C6H4)–C„C–H (5c)
k
max/nm (e/dm3 molꢁ1 cmꢁ1) 472 (28200), 556 (sh, 9500)
in CH2Cl2; 472 (26500), 554 (sh, 9000) in CH3CN.
Anal. Calc. for C45H29N4NiP: C, 75.5; H, 4.1; N, 7.8.
Found: C, 75.6; H, 4.1; N, 7.9%. IR m/cmꢁ1: m(C„C)
2096, m(C„N) 2222 (sh), 2212, m(CC–H) 3300 (CH2Cl2);
m(C„C) 2223 (sh), 2095, m(C„N) 2213, m(CC–H) 3300
(KBr). 1H NMR (CDCl3): d 6.8–8.8 [23H, m, C6H4,
C6H4 and PPh3], 5.22 [5H, s, C5H5], 1.61 [1H, s, CC–H].
13C NMR (CDCl3): d 201.1 [br], 156.1, 144.2, 143.0, 120–
135, 114.9, 114.8, 113.2, 112.9, 95.9, 82.3, 79.7, 77.3.
2.4.3. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(1,3-C6H4)–C„C–Ni(g5-C5H5)(PPh3)
(6c)
Anal. Calc. for C68H48N4Ni2P2: C, 74.2; H, 4.4; N, 5.1.
Found: C, 74.2; H, 4.3; N, 5.0%. IR m/cmꢁ1: m(C„C) 2094,
m(C„N) 2222 (sh), 2212 (CH2Cl2); m(C„C) 2094, m(C„N)
2223 (sh), 2213 (KBr). 1H NMR (CDCl3): d 6.64–7.85
[38H, m, C6H4, C6H4 and PPh3], 5.26 [5H, s, C5H5], 5.25
[5H, s, C5H5]. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 476 (45000),
563 (sh, 20000) in CH2Cl2; 473 (45000), 557 (sh, 21000)
in CH3CN.
k
max/nm (e/dm3 molꢁ1 cmꢁ1) 473 (18900), 560 (sh, 10000)
in CH2Cl2; 480 (17800), 562 (sh, 9000) in CH3CN.
2.3.4. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(4,40-C6H4–C6H4)–C„C–H (5d)
Anal. Calc. for C51H33N4NiP: C, 77.6; H, 4.2; N, 7.1.
Found: C, 77.3; H, 4.2; N, 7.0%. IR m/cmꢁ1: m(C„C)
2096, m(C„N) 2212, m(CC–H) 3300 (CH2Cl2); m(C„C)
2095, m(C„N) 2213, m(CC–H) 3300 (KBr). 1H NMR
(CDCl3): d 6.86–7.93 [27H, m, C6H4, C6H4C6H4, and
PPh3], 5.26 [5H, s, C5H5], 1.53 [1H, s, C„C-H]. kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 472 (29800) in CH2Cl2; 470 (30300)
in CH3CN.
2.4.4. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(4,40-C6H4–C6H4)–C„C–Ni(g5-C5H5)
(PPh3) (6d)
Anal. Calc. for C74H52N4Ni2P2: C, 75.5; H, 4.4; N, 4.7.
Found: C, 75.6; H, 4.5; N, 4.7%. IR m/cmꢁ1: m(C„C) 2094,
m(C„N) 2223 (sh), 2212 (CH2Cl2); m(C„C) 2094, m(C„N)
2223 (sh), 2213 (KBr). 1H NMR (CDCl3): d 6.92–8.13
[42H, m, C6H4, C6H4C6H4, and PPh3], 5.24 [5H, s,
C5H5], 5.21 [5H, s, C5H5]. 13C NMR (CDCl3): d 155.6,
144.8, 142.3, 120–135, 115.0, 113.6, 95.9, 92.8. kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 474 (40200) 555 (sh, 17900) in
CH2Cl2; 471 (35900), 556 (sh, 16000) in CH3CN.
2.4. The reactions of Ni(g5-C5H5)(PPh3)–C„C–X–
C„C–Ni(g5-C5H5)(PPh3) with TCNQ
When these were carried out as above with equimolar
amounts of TCNQ (0.04 g, 0.19 mmol) and Ni(g5-

P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
385
2.4.5. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C{@C(CN)2}–C{@C6H4@C(CN)2}–
Ni(g5-C5H5)(PPh3) (7a)
(CH2Cl2); m(C„N) 2213 (KBr). 1H NMR (CDCl3): d 6.77–
8.02 [42H, m, C6H4, C6H4, and PPh3], 5.26 [10H, s, C5H5].
k
max/nm (e/dm3 molꢁ1 cmꢁ1) 473 (42200) 555 (sh, 19000)
Anal. Calc. for C74H48N8Ni2P2: C, 72.3; H, 3.9; N, 9.1.
in CH2Cl2; 473 (43000), 553 (sh, 19600) in CH3CN.
Found: C, 72.3; H, 3.9; N, 9.0%. IR m/cmꢁ1: m(C„N) 2222
1
(sh), 2212 (CH2Cl2); m(C„N) 2223 (sh), 2212 (KBr). H
2.4.8. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
NMR (CDCl3): d 6.95–8.02 [38H, m, C6H4, and PPh3],
5.20 [10H, s, C5H5]. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 472
(36,500) 551 (sh, 16900) in CH2Cl2; 472 (34400), 550 (sh,
15100) in CH3CN.
C{@C(CN)2}-(4,40-C6H4–C6H )–C{@C(CN)2}–
4
C{@C6H4@C(CN)2}–Ni(g5-C5H5)(PPh3) (7d)
Anal. Calc. for C86H56N8Ni2P2: C, 74.8; H, 4.1; N, 8.1.
Found: C, 74.8; H, 4.1; N, 8.1%. IR m/cmꢁ1: m(C„N) 2212
(CH2Cl2); m(C„N) 2213 (KBr). 1H NMR (CDCl3): d 6.84–
7.96 [46H, m, C6H4, C6H4C6H4, and PPh3], 5.20 [10H, s,
C5H5]. 13C NMR (CDCl3): d 202.4 [d, J = 25 Hz], 156.8,
144.9, 143.6, 121–134, 115.5, 115.4, 114.1, 114.0, 96.7,
69.95. kmax/nm (e/dm3 molꢁ1 cmꢁ1) 477 (30400) 562 (sh,
12000) in CH2Cl2; 474 (29800), 553 (sh, 13200) in CH3CN.
2.4.6. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(1,4-C6H4)–C{@C(CN)2}–
C{@C6H4@C(CN)2}–Ni(g5-C5H5)(PPh3) (7b)
Anal. Calc. for C80H52N8Ni2P2: C, 73.6; H, 4.0; N, 8.6.
Found: C, 73.5; H, 4.1; N, 8.6%. IR m/cmꢁ1: m(C„N) 2222
1
(sh), 2212 (CH2Cl2); m(C„N) 2223 (sh), 2213 (KBr). H
NMR (CDCl3): d 6.91–7.90 [42H, m, C6H4, C6H4, and
PPh3], 5.25 [10H, s, C5H5]. 13C NMR (CDCl3): d 140.6,
144.3, 162.1, 121–135, 115.4, 115.3, 114.0, 96.5. kmax/nm
(e/dm3 molꢁ1 cmꢁ1) 475 (25200) 562 (sh, 11000) in
CH2Cl2; 478 (25900), 553 (sh, 10600) in CH3CN.
2.5. Crystal structure determinations of Ni(g5-C5H5)
(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–C6H5}
(4a), Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}–C6H4–C6H5-4} (4b) and Ni(g5-C5H5)
(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–
H.0.5(C2H5)2O (4l)
2.4.7. Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–
C{@C(CN)2}-(1,3-C6H4)–C{@C(CN)2}–
Crystals of 4a (black blocks), 4b (black plates) and
4l ꢀ 0.5(C2H5)2O (purple plates) were grown from acetoni-
trile/ether. Data were collected for 4a and 4l at 88(2) K
on a Bruker APEXII CCD diffractometer and for 4b at
C{@C6H4@C(CN)2}–Ni(g5-C5H5)(PPh3) (7c)
Anal. Calc. for C80H52N8Ni2P2: C, 73.6; H, 4.0; N, 8.6.
Found: C, 73.7; H, 4.0; N, 8.5%. IR m/cmꢁ1: m(C„N) 2212
Table 1
Crystal data for Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–C6H5 (4a), Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–C6H4–
C6H5-4, 4b, and Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–H ꢀ 1/2(C2H5)2O, 4l ꢀ 1/2(C2H5)2O
Compound
4a
4b
4l ꢀ 1/2(C2H5)2O
Chemical formula
Formula weight
T (K)
C
691.38
90(2)
0.71073
43H29N4NiP
C49H33N4NiP
767.47
163(2)
0.71073
C39H30N4O0.5NiP
652.35
90(2)
0.71073
˚
k (A)
Crystal system
Monoclinic
Orthorhombic
Monoclinic
Space group
P21/n
10.3756(8)
10.1379(8)
32.667(2)
Pca2(1)
26.263(9)
11.347(4)
26.306(9)
C2/c
13.4239(3)
22.6219(6)
21.9641(5)
˚
a (A)
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
90
98.225(5)
90
3400.8(5)
90
90
90
7839(5)
90
95.641(1)
90
6637.6(3)
3
˚
V (A )
Z
4
8
8
Dcalc (Mg mꢁ3
)
1.350
0.655
1.301
0.576
1.306
0.668
l (mmꢁ1
)
Transmission factors (Tmin, Tmax
Reflections collected
)
0.981, 0.711
20995
0.960, 0.877
96160
0.980, 0.902
68746
Independent reflections [Rint
]
6670 [0.0866]
4667
26.26
R1 = 0.0800, wR2 = 0.2038
R1 = 0.1113, wR2 = 0.2184
2.300 and ꢁ0.591
15876 [0.0697]
11363
26.43
9342 [0.0531]
6760
31.02
R1 = 0.0412, wR2 = 0.1139
R1 = 0.0642, wR2 = 0.1238
1.061and ꢁ0.827
Observed reflections I > 2r(I)
hmax (°)
Final R indicesa [I > 2r(I)]
R indices (all data)a
R1 = 0.0339, wR2 = 0.0642
R1 = 0.0594, wR2 = 0.0689
0.703 and ꢁ0.279
2
ꢁ3
˚
Largest difference in peak and hole (e A
)
2
a
w ¼ 1=½r2ðF o2Þ þ ð0:0944PÞ þ 10:5457Pꢂ where P ¼ ðF o2 þ 2F 2c Þ=3
for
4a;
w ¼ 1=½r2ðF 2oÞ þ ð0:0327PÞ ꢂ where P ¼ ðF o2 þ 2F 2c Þ=3
for
4b;
2
w ¼ 1=½r2ðF o2Þ þ ð0:0710PÞ þ 1:0322Pꢂ where P ¼ ðF o2 þ 2F 2c Þ=3 for 4l ꢀ 1/2(C2H5)2O.

386
P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
Fig. 1. The molecular structure and atom labelling of Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–C6H5 (4a). For clarity, only two C atoms
of the consecutively numbered cyclopentadienyl and phenyl rings are labelled.
Fig. 2. The molecular structure and atom labelling of Molecule 1 of Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–C6H4–C6H5-4 (4b). For
clarity, only two C atoms of the consecutively numbered cyclopentadienyl and phenyl rings are labelled.

P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
387
163(2) K on a Bruker SMART CCD diffractometer. Data was
3. Results and discussion
collected using SMART [25] or APEXII [26] and processed
using SAINT [27]; empirical absorption corrections were
applied using SADABS [28]. Crystal data for all three com-
pounds are summarised in Table 1.
The r-alkynyl complexes Ni(g5-C5H5)(PPh3)–C„C–R
(1) {R = (a) C6H5, (b) 4-PhC6H4, (c) 4-Me2NC6H4, (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), (j) 2-C4H3S (2-thie-
nyl), (k) C10H9Fe (ferrocenyl), (l) H}, Ni(g-C5H5)(PPh3)–
C„C–X–C„CH (2) and Ni(g5-C5H5)(PPh3)–C„C–X–
C„C–Ni(g5-C5H5)(PPh3) (3), {X = (a) nothing, (b)
1,4-C6H4, (c) 1,3-C6H4 and (d) 4,40-C6H4–C6H4} react with
7,7,8,8-tetracyanoquinodimethane, TCNQ, at 30 °C by
insertion of the alkyne C„C into a C@C(CN)2 bond of
TCNQ. 1 and 2 give 1:1 adducts Ni(g5-C5H5)(PPh3)–
C{@C6H4@C(CN)2}–C{@C(CN)2}–R (4) and Ni(g5-C5H5)
(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–X–C„CH (5),
respectively, whilst 3 give 1:1 adducts Ni(g5-C5H5)
(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–X–C„
C–Ni(g5-C5H5)(PPh3) (6) and 1:2 adducts Ni(g5-C5H5)
(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–X–C{@
C(CN)2}–C{@C6H4@C(CN)2}–Ni(g5-C5H5)(PPh3) (7)
depending on the mole ratio of reactants (Scheme 1). These
intensely coloured solids are air-stable. They decompose
above ca. 150 °C on heating. They are soluble in polar
organic solvents, but their red–purple solutions decompose
The structures of 4a and 4b were solved using SHELXS
[29] and that of 4l using SIR92 [30] and were refined by
full-matrix least-squares on F2 using SHELXL-97 [31] and
TITAN2000 [32]. All non-hydrogen atoms were assigned
anisotropic temperature factors, with hydrogen atoms
included in calculated positions. Crystals of 4a were weakly
diffracting which led to a poorer quality data set and rela-
tively high values of Rint and R1. For 4b, the correct choice
of absolute structure was confirmed by refinement of the
Flack parameter [0.008(8)] [33]. For 4l, a difference Fourier
synthesis following the location of all non-hydrogen atoms
revealed three substantial peaks that could be readily
assigned to a diethyl ether solvate molecule in the crystal
lattice with the O atom located on a two-fold axis. Aniso-
tropic refinement of this solvate with H atoms included
using a riding model led to a significant improvement in
R1. The structure of 4a together with the atom labelling
is illustrated in Fig. 1, and those of molecule A of 4b and
4l in Figs. 2 and 3, respectively. Selected bond lengths
and angles are listed in Table 2.
Fig. 3. The molecular structure and atom labelling Ni(g5-C5H5)(PPh3)–C{@C6H4@C(CN)2}–C{@C(CN)2}–H (4l). For clarity, only two C atoms of the
consecutively numbered cyclopentadienyl and phenyl rings are labelled.

388
P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
Table 2
slowly. Consequently, although the reactions which form
5
˚
Selected bond lengths (A) and bond angles (°) for Ni(g -C5H5)(PPh3)-
C{C6H4C(CN)2}C{C(CN)2}C6H5 (4a),Ni(g5-C5H5)(PPh3)C{C6H4C(CN)2}-
C{C(CN)2}C6H4C6H5-4 (4b) (molecule A only; molecule B is very similar)
and Ni(g5-C5H5)(PPh3)C{C6H4C(CN)2}C{C(CN)2}H ꢀ 1/2(C2H5)2O (4l) ꢀ
1/2(C2H5)2O
3–7 appear to be close to quantitative, purification results
in loss of product and the yields of the pure compound
are lower but always >80%.
3.1. Structures of 4a, 4b (molecule A) and 4l
4a
4b (molecule A)
4l ꢀ 1/2(C2H5)2O
Coordination about Ni
Ni(1)–P(1)
Ni(1)–C(5)
The spectroscopic data discussed below does not allow
the molecular structures of 4–7 to be deduced unambigu-
ously, although it does confirm that all have similar struc-
tures. Consequently the structures of three were determined
by X-ray crystallography, 4a (R = Ph), 4b (R = 4-Ph–
C6H4) and 4l (R = H). The molecular structures and atom
labelling of 4a, 4b and 4l are illustrated in Figs. 1–3, respec-
tively, whilst selected bond lengths and angles are summa-
rised in Table 2. In the discussion that follows 4a will be
used as the generic example for the aryl derivatives as its
structure is closely similar to that of 4b. Complex 4b crys-
tallises with two unique molecules in the asymmetric unit,
small differences between the two can be ascribed to crystal
packing effects. The structure of 4l is somewhat different
and will be discussed separately.
The crystal structure of 4e (R = 2-C10H7) was also
determined, but is not reported because of disorder within
the naphthyl group that it was not possible to model effec-
tively. However, the principal molecular parameters for 4e
are very similar to those of 4a and the two independent
molecules of 4b.
In 4a, 4b and 4l the alkyne C„C has inserted into a
C@C bond linking one C(CN)2 moiety to the quinonoid
ring of TCNQ. There are two possible isomeric products
from this reaction, but the only one observed has the
C(CN)2 residue attached to C2 of Ni(g5-C5H5)(PPh3)–
C1„C2–R and C6H4C(CN)2 to C1, both by C@C bonds.
The same isomer was obtained from the reaction of TCNQ
with trans-Pt(PMe3)2(C„C–Me)2 [13,14].
2.1818(15)
1.1912(5)
2.135(6)
2.094(6)
2.164(5)
2.136(5)
2.109(6)
1.403(9)
1.434(8)
1.388(8)
1.455(8
2.1960(10)
1.911(3)
2.113(3)
2.194(3)
2.137(4)
2.122(3)
2.151(3)
1.421(4)
1.388(5)
1.456(5)
1.472(4)
1.418(4)
98.98(9)
2.1536(5)
1.8798(18)
2.142(2)
2.1019(19)
2.152(2)
2.080(2)
2.130(2)
1.442(3)
1.409(3)
1.397(3)
1.438(3)
1.376(3)
97.66(6)
Ni(1)–C(21)
Ni(1)–C(22)
Ni(1)–C(23)
Ni(1)–C(24)
Ni(1)–C(25)
C(21)–C(22)
C(22)–C(23)
C(23)–C(24)
C(24)–C(25)
C(21)–C(25)
P(1)–Ni(1)–C(5)
1.395(9)
100.29(16)
C@C6H4@C(CN)2 fragment
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
C(6)–C(11)
C(9)–C(12)
C(12)–C(13)
C(12)–C(14)
C(13)–N(13)
1.367(7)
1.391(4)
1.448(4)
1.357(4)
1.435(5)
1.446(5)
1.355(5)
1.457(4)
1.385(5)
1.427(5)
1.445(5)
1.161(5)
1.142(4)
112.7(2)
126.4(2)
120.9(3)
123.3(3)
121.7(3)
121.9(3)
116.7(3)
122.1(3)
121.1(4)
121.9(3)
121.4(3)
123.0(3)
121.1(3)
115.8(3)
179.0(4)
179.1(4)
1.375(3)
1.447(3)
1.353(3)
1.430(3)
1.440(3)
1.349(3)
1.439(3)
1.386(3)
1.426(3)
1.424(3)
1.146(3)
1.153(3)
105.13(13)
130.46(14)
124.16(17)
122.34(17)
121.84(18)
121.07(18)
117.79(17)
120.88(17)
122.19(17)
120.94(17)
121.27(18)
120.95(13)
122.06(18)
116.99(18)
179.3(3)
1.449(7)
1.350(7)
1.435(7)
1.441(7)
1.349(8)
1.445(7)
1.392(7)
1.434(8)
1.429(8)
1.146(7)
1.161(7)
113.5(4)
120.6(5)
121.0(5)
124.3(5)
122.5(5)
121.4(5)
117.1(5)
121.1(5)
122.8(5)
122.4(5)
120.4(5)
123.2(5)
120.0(5)
116.7(5)
178.9(6)
177.1(6)
C(14)–N(14)
Ni(1)–C(5)–C(4)
Ni(1)–C(5)–C(6)
C(4)–C(5)–C(6)
C(5)–C(6)–C(7)
C(6)–C(7)–C(8)
C(7)–C(8)–C(9)
C(8)–C(9)–C(10)
C(9)–C(10)–C(11)
C(6)–C(11)–C(10)
C(8)–C(9)–C(12)
C(10)–C(9)–C(12)
C(9)–C(12)–C(13)
C(9)–C(12)–C(14)
C(13)–C(12)–C(14)
C(12)–C(13)–N(13)
C(12)–C(14)–N(14)
In 4l the coordination about Ni is similar to that found
in many other [Ni(g5-C5H5)(PPh3)X] derivatives with the
P–Ni–C plane ca. perpendicular to the cyclopentadienyl
plane, 89.0(7)°. It is a b isomer (cf. Ref. [24] and references
therein) with the P(1)–Ni–C(5) plane oriented so that it is
also approximately perpendicular to the rv plane of the
(idealised) (g5-C5H5)Ni moiety and an ene/enyl distortion
of the cyclopentadienyl ligand, C(21)–C(25)/C(22)–C(23)–
C(24), respectively. The C(5)–Ni–P angle at 97.66(6)° is
at the high end of expectations and larger than that in 1l,
179.6(3)
C@C(CN)2 fragment
C(3)–C(4)
C(4)–C(5)
C(4)–C(61)
C(1)–C(3)
C(2)–C(3)
C(1)–N(1)
C(2)–N(2)
C(3)–C(4)–C(5)
C(3)–C(4)–C(61)
C(5)–C(4)–C(61)
C(1)–C(3)–C(4)
C(2)–C(3)–C(4)
C(1)–C(3)–C(2)
N(1)–C(1)–C(3)
N(2)–C(2)–C(3)
1.361(8)
1.472(7)
1.497(7)
1.450(8)
1.442(8)
1.149(7)
1.152(7)
122.6(5)
119.1(5)
118.4(5)
121.4(5)
121.0(5)
117.6(5)
179.0(6)
179.4(6)
1.353(4)
1.478(4)
1.494(4)
1.444(5)
1.440(4)
1.142(4)
1.142(4)
120.3(3)
119.8(2)
119.8(3)
122.6(3)
122.6(3)
114.8(3)
178.1(4)
177.7(4)
1.363(3)
1.441(3)
˚
90.29(15)° [24]. The Ni(1)–P(1) distance, 2.1536(5) A, is
1.434(3)
1.438(3)
1.136(3)
1.144(3))
124.55(17)
comparable those in related [Ni(g5-C5H5)(L)R] complexes,
˚
2.13–2.16 A [24,34–37].
˚
The Ni–C(5) bond length, 1.8798(18) A, is greater than
˚
that in 1l, 1.850(5) A [24], a difference which may be due
to the sp2 hybridised C(5) in 4l and the sp hybridised
C(1) in 1l. The C{@C6H4@C(CN)2}C{C(CN)2}–H ligand
is unusual in that all carbon atoms except those of the
cyano groups are formally sp2 hybridised, but the whole
ligand is not planar. The (NC)2C(9)@C6H4@C(5)–Ni(1)
part of 4l is effectively planar with angles of 1.94(4)° and
120.79(17)
122.46(18)
116.73(16)
179.3(2)
176.9(2)

P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
389
NC CN
NC CN
H
(i)
(i)
Ni
R
Ni
X
Ni
R
X
H
Ni
NC
PPh3
CN
NC CN
PPh3
PPh3
PPh3
1
4
2
5
PPh
3
PPh3
Ni
NC CN
CN
NC CN
NC
X
PPh3
Ni
Ni
(i)
(i)
Ni
X
Ni
X
Ni
CN
NC CN
PPh3
NC
NC CN
PPh3
PPh3
3
6
7
Scheme 1. (i) TCNQ/30 °C/CH2Cl2. X = nothing, 1,4-C6H4, 1,3-C6H4 and 4,40-C6H4–C6H4.
1.48(3)° between the (NC)2C, C6H4 and Ni(1)C(5)C(4)C(6)
planes within it. It lies at 85.10(3)° to the P–Ni(1)–C(5)
plane of coordination about Ni, and at 70.68(4)° to the sec-
ond important plane within the ligand which is defined by
C(4)C(3)(CN)2. The cis diene system C(3)@C(4)–
C(5)@C(6) is non-planar with a torsion angle of 68.2(3)°.
The C–C bond lengths lie in the ranges 1.349(3)–
CH–C(C6H4NMe2-4)@C(CN)2 where the phenyl ring is
twisted out of the plane of the C@C(CN)2 system by steric
effects [39]. The cis diene system C(3)@C(4)–C(5)@C(6) is
non-planar with a torsion angle of 75.8(7)°. The C–C bond
˚
lengths lie in the ranges 1.350(7)–1.392(7) A for those
which are formally double bonds, and 1.429(8)–
˚
1.450(8) A for those which are formally single bonds.
˚
1.386(3) A for those which are formally double bonds,
However, the two single bonds to C(4) are somewhat
˚
˚
and 1.426(3)–1.447(3) A for those which are formally single
longer with C(4)–C(5) = 1.472(7) A and C(4)–C(61)(phe-
˚
bonds, and those of the C6H4C(CN)2 moiety are similar to
those of TCNQ itself [38]. Although most C–C–C bond
angles lie close to 120°, coordination about C(5) is severely
distorted with Ni(1)–C(5)–C(4) = 105.13(13)°, Ni(1)–C(5)–
C(6) = 130.46(14)° and C(4)–C(5)–C(6) = 124.16(17)°
(sum = 359.75°). This appears to be due to an interaction
between the Ni centre and C(4) as the Niꢀ ꢀ ꢀC(4) separation
nyl) = 1.497(7) A. Again, this implies reduced or absent
conjugation across these bonds. The dimensions of the
C6H4@C(CN)2 moiety are also similar to those of TCNQ
itself [38]. The C–C–C bond angles lie between 112.7°
and 126.4°, with particular distortion about C(5). C(4)–
C(5)–C(6) is 121.0(5)°, but Ni(1)–C(5)–C(6) is 125.5(4)°
and Ni(1)–C(5)–C(4) is 113.5(4)° (sum = 360°). This
appears to be due to an interaction between Ni(1) and
˚
˚
is only 2.6502(18) A, whereas the sum of their Van der
˚
Waal’s radii is 3.4 A. The nature of the substituents on
C(4), separation = 2.840(5) A, which is similar to, but
C(4) suggests that this is a Ni ? C(4) donor–acceptor
interaction.
weaker than, that observed for 4l.
It seems reasonable to suggest that the steric effects of
the phenyl (or biphenyl) group are responsible for the
structural differences between 4a (or 4b) and 4l.
In 4a the H of 4l is replaced by a phenyl group.
Although the structures of the two are closely related, there
are differences which are largely associated with that part
of the molecule derived from the [Ni(g5-C5H5)(PPh3)CCR]
precursor. 4a is an ab isomer where the P–Ni–C plane is
oriented so that the P atom eclipses C(22) of the g-C5H5
ligand which is distorted towards a diene, C(21)–C(25)–
3.2. Spectra
The IR spectra of 4–7 are similar in that they all show a
single strong absorption band at 2212 cmꢁ1 which often
has a weaker shoulder at 2223 cmꢁ1. These are assigned
to the m(CN) vibrations of the complexes; the shoulder
occurs at the same frequency as the m(CN) vibration of
TCNQ itself. The spectra of 5 and 6 also show a band at
ca. 2095 cmꢁ1 due to the m(C„C) mode of the unreacted
C„C, and for 5 there is another band at 3300 cmꢁ1 char-
acteristic of a m(H–CC) vibration.
˚
C(24)–C(23). Both the Ni–P distance, 2.1818(15) A,
and C(5)–Ni–P angle at 100.29(16)° are even larger
˚
than those in 4l, but the Ni–C(5) bond length, 1.912(5) A,
is comparable within experimental error. The
(NC)2C(9)@C6H4@C(5)–Ni(1) part of 4a is no longer pla-
nar with an angles of 6.8(7)° and of 5.2(4)°, respectively,
between the (NC)2C(9), the C6H4 and Ni(1)C(5)C(4)C(6)
planes. The Ni(1)C(5)C(6) plane is at an angle of 69.9° to
the P(1)–Ni(1)–C(5) plane. The Ni(1)–C(5)–C(6) plane lies
at 73.7(3)° to the second important plane within the ligand
which is defined by C(4)C(3)(CN)2, and this last plane lies
at an angle of 79.0(1)° to the phenyl ring defined by C(61)–
C(66). A similar situation has been encountered in deriva-
tives of 1,1-dicyanobuta-1,3-dienes such as (MeS)2C@
1
With the exception of 4k, the H NMR spectra of all 4
show a singlet signal at d 5.33–5.41 due to their (g5-
C5H5)Ni protons, but those due to the Ph3P, C6H4C(CN)2
and aryl groups of 4a–4k often overlap to such an extent
that their unambiguous identification and assignment was
usually not possible. However, when R = H, 4l, the aryl
group resonances are absent; the Ph3P ligand gives rise to

390
P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
a complex multiplet between d 7.2–7.6, the unique H to a
singlet at d 7.07, and the C6H4 protons to four separate res-
onances. Those at d 6.58 and 6.79 couple as do those at d
7.06 and 7.78 (J = 9.5 Hz). A further weak coupling is
detectable with J = 1.3 Hz to the d 6.58/6.79 pair and
J = 1.8 Hz to the d 7.06/7.78 pair. In 4k with its ferrocenyl
end group, the obscuring aryl group resonances are also
absent and here the C6H4 give rise to doublet resonances
at d (J in Hz) 6.93 (9.1), 7.03(9.0), 7.12 (9.7) and 8.18
(9.4). These are somewhat more deshielded than those of
4l, but are comparable to those of the phenanthryl deriva-
tive 4f (d 6.97, 7.04, 7.22, 8.24) and of other compounds
where only some of these resonances could be identified.
The absence of the aryl group in 4l also allows its 13C
NMR spectrum to be assigned with confidence. The
(g-C5H5) group gives rise to a singlet at d 94.9, and the
Ph3P ligand to three strong signals. These comprise a sin-
glet at d 131.6 and two doublets at d 128.9 (J = 10.8 Hz)
and 133.4 (J = 11 Hz) plus a weaker doublet at d 130.1
(J = 49 Hz) which are due to p, m, o and ipso carbon
atoms, respectively. The four cyano groups are responsible
for the four signals at d 112.7, 114.4, 114.7 and 114.8; com-
parable chemical shifts are found for other derivatives con-
taining the @C(CN)2 group. A combination of NOESY,
HSQC and gHMBC techniques allow the following 13C
(1H) assignments C(3) d 69.6 (ꢁ), C(4) d 161.3 (7.07),
C(5) d 201.3 (ꢁ), C(6) d 143.0 (ꢁ), C(7) d 129.6 (6.56),
C(8) d 120.1 (6.78), C(9) d 156.2 (ꢁ), C(10) d 124.5
(7.04), C(11) d 141.7 (7.77), C(12) d 70.7 (ꢁ). The highly
deshielded resonance due to C(5), is a very weak doublet
with J = 26 Hz, presumably due to coupling with 31P. It
is also detectable through its correlation with H(4) in the
gHMBC spectrum. In TCNQ itself, the observed reso-
nances are d 150.8 {C@C(CN)2}, 131.3 (C–H), 111.6
(CN) and 89.8 {C=C(CN)2} [40] whilst for 1,1-dicyanobu-
ta-1,3-dienes of the general type MeS(D)C@C(H)–
Cb(C6H4X)@Ca(CN)2 where D = MeS or Me2N the
chemical shifts d for CN = 113.3–117.6, Ca = 62.7–78.6,
Cb = 163.9–169.8 [39], and for various M-C3{@C4(CN)2}-
{C2(Ph)@C1(CN)2} derivatives where M = W(g5-C5H5)-
(CO)3, Ru(g5-C5H5)(DPPE) or Ru(g5-C5H5)(CNBut)2 the
chemical shifts d for resonances due to C1 = 69.3–77.4,
C2 = 179.7–182.8, C3 = 215.1–226.2 and C4 = 90.8–99.8
[5].
M-C3{@C4(CN)2}{C2(Ph)@C1(CN)2} derivatives above, d
179.7–182.8. The signals due to C(4) and C(5), now both
quaternary, are very weak and not always observed. In
favourable instances that at d ca. 200 due to C(5) can be
resolved into doublet, J = 26 Hz, as a consequence of
C–31P coupling, otherwise both are rather broad.
The NMR spectra of the di-nickel complexes 5–7 follow
the same general pattern as those of 4, but with predictable
differences, and the often greater constraints due to solubil-
ity problems means that few are completely satisfactory
13C NMR spectra were obtained. 5 show resonances at
ca. d 1.53–1.70 (1H NMR) and d ca. 80 (13C NMR) char-
acteristic of the H–C„C group. For 6, the two different
Ni(g5-C5H5)(PPh3) moieties each give rise to a C5H5 reso-
nance, and the Ni–C1„C2 moieties gives rise to a doublet
at ca. d 83.5–88.6 (J = 48.1 Hz) and a singlet at d 100.4–
118.4 due to C1 and C2, respectively, (cf. d 86.2 with
J = 48 Hz and 119.6 for 1a). Unfortunately, in no case
could the intrinsically weak signals at ca. d ca. 180 and d
ca. 200 be detected.
The electronic spectra of all 4–7 show a broad intense
absorption band at ca. 470–480 nm with a shoulder at ca.
580 nm. This suggests that all 4–7 contain similar or iden-
tical chromophores. There are additional absorption bands
in the spectra of 4g (394 nm), 4i (455 nm) and 4k (630 nm)
which are probably due to low energy transitions that are
essentially localised within the anthryl, perylenyl and ferr-
ocenyl end-groups respectively. Such transitions are found
at ca. 375 and 355 nm in anthracene, and ca. 434, 406 and
387 nm in perylene [41].
There are two potential Donor–p–Acceptor moieties
within the molecules of 4–7, D–C(Y)@C(CN)2 and
Ni–C(R0)@C6H4@C(CN)2 where the acceptors are both
C(CN)2 and the donors D or Ni; D = R, H, X–C„CH,
X–C„C–Ni(g5-C5H5)(PPh3)
or
X–C{@C(CN)2}–
C{@C6H4@C(CN)2}–Ni(g5-C5H5)(PPh3). The first of
these is unlikely to be the effective chromophore as the
spectra are independent of D even when it is the powerful
donor 4-Me2NC6H4. Furthermore, in the solid state at
least for 4a and 4b the phenyl plane lies at ca. 58–80° to
the plane of the RC@C(CN)2 chromophore which hinders
the necessary conjugation between aryl donor and CN
acceptor and results in a long C(4)–C(61) bond. Further
evidence is provided by the spectrum of the ferrocenyl
derivative 4k which confirms that it does not contain a func-
tioning Fc–C@C(CN)2 chromophore {for Fc–CH@C(CN)2,
kmax 326 nm (e = 14000 Mꢁ1 cmꢁ1), 534 nm (e =
2400 Mꢁ1 cmꢁ1)} [16]. Consequently the spectroscopic evi-
dence suggests that Ni–C(R0)@C6H4@C(CN)2 is the effec-
tive chromophore in 4–7. This is supported by the
crystallographic evidence which shows that in 4l it is planar
and in 4a and 4b it is close to planar, which allows effective
p-communication between the electron-rich Ni donor and
the cyano acceptors. This chromophore maybe described
by a mixture of resonance forms, Fig. 4. Bond lengths sug-
gest that in the ground state A predominates, but others are
possible in which there is charge separation and of partic-
In general, the 13C NMR spectra of 4 usually show
fewer signals than would be expected, perhaps due to the
poor solubility of some compounds and the long relaxation
times of some of the tertiary carbon atoms. Furthermore,
the presence of Ph3P, C6H4C(CN)2 and aryl groups can
make it difficult to assign the observed resonances. Even
for the simplest aryl group, C6H5, some of its 13C reso-
nances lie very close to or coincide with those due to the
Ph3P ligand. However, the most obvious difference between
the 13C NMR spectra of 4l and the other 4 is the chemical
shift of the Ni–C–C(4)@C(CN)2 resonance which has d
161.3 for 4l but d 181–184 in other 4. These chemical
shifts should be compared with those for C2 in the

P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
391
for this is unambiguous. The IR spectra of 5 all show an
absorption band at ca. 3300 cmꢁ1 due the m(H–CC) vibra-
tion, their H NMR spectra show a H–C„C resonance at
N
N
N
Ni
C
C
Ni
C
C
1
ca. d 1.6, and their 13C NMR spectra (when obtainable)
show singlet HC„C resonances at ca. d 80, respectively,
rather than the doublet at ca. d 87 and singlet at ca. d
100–120 which would be expected for a Ni(g5-C5H5)-
(PPh3)–C„C moiety. This behaviour contrasts with that
of W(g5-C5H5)(CO)3–C„C–C„C– Fc (Fc = ferrocenyl)
which reacts with TCNE to form W(g5-C5H5)(CO)3–
C„C–C{@C(CN)2}–C{@C(CN)2}–Fc i.e. the metal-
attached C„C is not the one which is attacked [11]. There
is no reaction between TCNQ and Fc–C„CH.
Z
Z
N
Fig. 4. Resonance forms of the Ni–C(Z)@C6H4@C(CN)2 chromophore in
4–7.
ular importance will be those in which the C6 ring is aro-
matic, e.g. B, Fig. 4. These charge-separated mesomers
probably make a larger contribution to the excited states
of the system than they do to the ground state.
4. Conclusions
3.3. Electrochemistry
C„C triple bonds in 1, 2 and 3 (two) which are directly
bonded to Ni are able to insert into one of the C@C(CN)2
double bonds of 7,7,8,8-tetracyanoquinodimethane, TCNQ,
The electrochemistries of 1 have been reported previ-
ously. 1a and 1l undergo a quasi-reversible oxidation with
Ep = 0.81 V and 0.83 V, respectively. For the TCNQ
adducts, 4l shows an irreversible oxidation, Ep = ca. 1 V,
and two reversible reductions at ꢁ0.26 and ꢁ0.47 V {vs.
Fe(g-C5Me5)2} (Fig. 5). TCNQ itself shows two reversible
reductions at 0.21 and ꢁ0.33 V (vs. SCE) [42]. In contrast
4a, chosen as typical of other 4, shows a quasi reversible
oxidation at ca. 1 V, which is characteristic of compounds
containing the Ni(g5-C5H5)(PPh3) moiety, plus compli-
cated reduction processes. Elucidation of such processes
for 4a and the apparently anomalous behaviour of 4l are
the subject of further investigation.
to give complexes 4, 5,
6 and 7 containing the
Ni–C{@C6H4@C(CN)2}–C{@C(CN)2}–X group (two such
groups in 7). However, no such reaction takes place between
TCNQ and the C„CH moieties of 2, even though they are
conjugated with Ni, or between TCNQ and normal alkynes
such as PhC„CH, PhC„CPh, 1,4-C6H4(C„CH)2 and
(g5-C5H5)Fe(g5-C5H4C„CH), (FcC„CH). This contrasts
with the reactions of C2(CN)4, TCNE, which with
FcC„CH, FcC„CFc and one of the triple bonds of
FcC„C–C„CFc to give tetracyanobutadiene derivatives
[41]. Clearly, TCNQ is a less reactive electrophile than
TCNE. Furthermore, only one of the two C@C(CN)2 bonds
of TCNQ reacts with 1–3 even when they are in excess.
Ni(g5-C5H5)(PPh3)-C{C6H4C(CN)2}-C{C(CN)2}-D
complexes contain two potential chromophores, Ni–
C@C6H4@C(CN)2 and D–C@C(CN)2, but as all 4, 5, 6 and
7 have almost identical visible spectra which are different
from those of known D–C@C(CN)2 derivatives, only the first
is effective. This is consistent with the molecular structures of
4a, 4b and 4l which show the NiC(Cb)@C6H4@C(CN)2 moi-
eties to be planar or close to it whilst the aryl groups are far
from coplanar with the C@C(CN)2 fragment. The X-ray dif-
fraction studies also show that there is a significant Ni ? Cb
@C(CN)2 interaction which is greater for R = H than for
R = Ph or 4-biphenyl.
3.4. Reaction pathway
The reactions of 1–3 with TCNQ are fast with no evi-
dence for the formation of intermediates such as the green
paramagnetic compound or the cyclobutenyl derivative
observed during the reaction of TCNE with W(g5-C5H5)-
(CO)3–C„C–Ph [5].
TCNQ inserts exclusively into the Ni-substituted C„C
of 2 rather than the C„CH. The spectroscopic evidence
8
6
4
Acknowledgements
2
0
P.B. thanks Enterprise Ireland and Schering-Plough
(Avondale) for financial support. We also thank the New
Zealand Foundation for Research Science and Technology
for a Postdoctoral Fellowship to C.J.M. and the Chemistry
Department, University of Otago for financial assistance.
-2
-4
-6
-8
-1.2
-1
-0.8
-0.6
-0.4
E /V
-0.2
0
0.2
Appendix A. Supplementary material
Fig. 5. Cyclic voltammogram of 4l (Pt/acetone/0.1 M TEAP/ vs. [Fe(g5-
CCDC 660589, 660590 and 660591 contain the supple-
mentary crystallographic data for 4a, 4b and 4l. These data
C5Me5)2]+/0, 0.0 V).

392
P. Butler et al. / Journal of Organometallic Chemistry 693 (2008) 381–392
[21] A.S. Hay, J. Org. Chem. 25 (1960) 637.
[22] K. Sonogashira, Y. Yatake, Y. Tohoda, S. Takahashi, N. Hagihara,
J. Chem. Soc., Dalton Trans. (1977) 291.
can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.jorganchem.2007.11.029.
[23] I.R. Whittall, M.P. Cifuentes, M.G. Humphrey, B. Luther-Davies,
´
M. Samoc, S. Houbrechts, A. Persoons, G.A. Heath, D. Bogsanyi,
Organometallics 16 (1997) 2631.
[24] J.F. Gallagher, P. Butler, R.D.A. Hudson, A.R. Manning, J. Chem.
Soc., Dalton Trans. (2002) 75;
P. Butler, J.F. Gallagher, A.R. Manning, H. Mueller-Bunz, C.J.
McAdam, J. Simpson, B.H. Robinson, J. Organomet. Chem. 690
(2005) 4545.
References
[1] A. Davidson, J. P Solar, J. Organomet. Chem. 166 (1979) C13.
[2] M.I. Bruce, T.W. Hambley, M.R. Snow, A.G. Swincer, J. Chem.
Soc., Chem. Commun. (1981) 271.
[3] P. Hong, K. Sonogashira, N. Hagihara, J. Organomet. Chem. 219
(1981) 363.
[4] M.I. Bruce, T.W. Hambley, J.R. Rodgers, M.R. Snow, A.G. Swincer,
J. Organomet. Chem. 226 (1982) C1.
[5] M.I. Bruce, T.W. Hambley, M.R. Snow, A.G. Swincer, Organome-
tallics 4 (1985) 501.
[25] SMART: Area Detector Control; Bruker AXS, Madison, WI, USA, 1994.
[26] APEXII V1.017, Diffractometer Control Software. Bruker AXS Inc.,
Madison, Wisconsin, USA, 2004.
[27] SAINT: Area detector integration software; Bruker AXS, Madison, WI,
USA, 1994 and 2004.
[28] SADABS (Absorption Correction for Area Detector Data); Bruker
AXS, Madison WI, USA, 1997 and 2004.
[29] G.M. Sheldrick, SHELXS-97. A Program for the Solution of Crystal
Structures from Diffraction Data, University of Go¨ttingen, Federal
Republic of Germany, 1990.
[6] Y. Yamamoto, R. Satoh, T. Tanase, J. Chem. Soc., Dalton Trans.
(1995) 307.
[30] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, J. Appl.
Crystallogr. 26 (1993) 343–350.
[7] K. Onitsuka, S. Takahashi, J. Chem. Soc., Chem. Commun. (1995)
2095.
[31] G.M. Sheldrick, SHELXL-97 A Program for the Refinement of Crystal
Structures, University of Go¨ttingen, Federal Republic of Germany,
1997.
[8] M.I. Bruce, M. Ke, P.J. Low, B.W. Skelton, A.H. White, Organo-
metallics 17 (1998) 3539.
[9] K. Onitsuka, N. Ose, E. Ozawa, S. Takahashi, J. Organomet. Chem.
578 (1999) 169.
[10] M.I. Bruce, B.C. Hall, P.J. Low, B.W. Skelton, A.H. White, J.
Organomet. Chem. 59 (2001) 74.
[11] M.I. Bruce, M.E. Smith, B.W. Skelton, A.H. White, J. Organomet.
Chem. 637–639 (2001) 484.
[12] Chao-Wan Chang, Ying-Chih Lin, Gene-Hsiang Lee, Yu Wang, J.
Chem. Soc., Dalton Trans. (1999) 4223.
[13] M. Masai, K. Sonogashira, N. Hagihara, J. Organomet. Chem. 34
(1972) 397.
[14] K. Onuma, Y. Kai, N. Yasuoka, N. Kasai, Bull. Chem. Soc. Jpn. 48
(1975) 1696.
[15] J.D. McKinney, P.A. Anderson, T.A. Hamor, C.J. Jones, A. Porch,
J. Organomet. Chem. 558 (1998) 147.
[16] J.F. Gallagher, R.D.A. Hudson, A.R. Manning, J. Simpson,
Unpublished work.
[17] K.W. Barnett, J. Chem. Ed. 519 (1974) 422.
[18] S. Myano, I. Izumi, H. Hashimoto, J. Chem. Soc., Dalton Trans.
(1995) 307.
[19] M. Matsumoto, K. Kuroda, Tetrahedron Lett. 21 (1980) 4021.
[20] L. Brandsma, Preparative Acetylenic Chemistry, Elsevier, Amster-
dam, 1988.
[32] K.A. Hunter, J. Simpson, TITAN2000 A molecular graphics program
to aid structure solution and refinement with the SHELX suite of
programs, University of Otago, New Zealand, 1999.
[33] H.D. Flack, Acta Crystallogr. Sect. B39 (1983) 876.
[34] R.H. Naulty, M.P. Cifuentes, M.G. Humphrey, S. Houbrechts, C.
Boutton, A. Persoons, G.A. Heath, D.C.R. Hockless, B.
Luther-Davies, M. Samoc, J. Chem. Soc., Dalton Trans. (1997)
4167.
[35] I.R. Whittall, M.G. Humphrey, D.C.R. Hockless, Aust. J. Chem. 51
(1998) 219.
[36] P. Butler, J.F. Gallagher, A.R. Manning, Inorg. Chem. Commun. 1
(1998) 343.
[37] J.F. Gallagher, P. Butler, A.R. Manning, Acta Crystallogr. C54
(1998) 342.
[38] R.E. Long, R.A. Sparks, K.N. Trueblood, Acta Crystallogr. 18
(1965) 876.
[39] T. Freier, M. Michalik, K. Peseke, H. Reinke, J. Chem. Soc., Perkin
Trans. 2 (1999) 1265.
[40] C.J. McAdam, Unpublished work.
[41] E. Clar, Polycyclic Hydrocarbons, Academic Press, London, 1964.
[42] T. Mochida, S. Yamazaki, J. Chem. Soc., Dalton Trans. (2002) 3559.