Synthesis of several functionalized cis-diisocyanide and fac-triisocyanide metal complexes

Article abstract of DOI:10.1016/S0022-328X(99)00185-0

cis-Diisocyanide metal complexes of the types cis-W(CNR)₂(CO)₄, cis-ReCl(CNR)₂(CO)₃, and Fe(η⁵-C₅H₅)Cl(CNR)₂ and fac-triisocyanide metal complexes of the types fac-W(C

Full text of DOI:10.1016/S0022-328X(99)00185-0

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 585 (1999) 26–34
Synthesis of several functionalized cis-diisocyanide and
fac-triisocyanide metal complexes
Luqin Yang a,1, Kung-Kuai Cheung a, Andreas Mayr b,*
a Department of Chemistry, The Uni6ersity of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong
b Department of Chemistry, State Uni6ersity of New York at Stony Brook, Stony Brook, New York, NY 11794-3400, USA
Received 25 February 1999
Abstract
cis-Diisocyanide metal complexes of the types cis-W(CNR)2(CO)4, cis-ReCl(CNR)2(CO)3, and Fe(h5-C5H5)Cl(CNR)2 and
fac-triisocyanide metal complexes of the types fac-W(CNR)3(CO)3 and [Fe(h5-C5H5)(CNR)3]Cl have been prepared. The
isocyanides are of the type 4-CNC6H2-3,5-i-Pr2-f, whereby the functionalities f are capable of forming strong coordinative bonds
to transition metals (f=CCH, CC-4-C5H4N, or CC-4,4%-biphenyl-C6H2-3,5-i-Pr2-4-NC) or capable of being interconnected with
each other by covalent bond formation (f=Br, I, CCSiMe3, CCH). The molecular structures of cis-W(4-CN-3,5-i-Pr2-C6H2CC-4-
C5H4N)2(CO)4, cis-ReCl(4-CN-3,5-i-Pr2-C6H2CCH)2(CO)3, and Fe(h5-C5H5)Cl(4-CN-3,5-i-Pr2-C6H2CC-4-C5H4N)2 have been
determined by X-ray crystallography. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Isocyanides; Metal complexes; Tungsten; Rhenium; Iron; X-ray structures
from molecular self-assembly are normally space-
filling [5], i.e. ‘open’ three-dimensional frameworks
may interpenetrate and/or include solvent molecules
or other guest molecules. This situation is well docu-
mented in the literature [6]. Interpenetrating three-di-
mensional structures are, of course, incapable of
unfolding the physical properties of the individual
networks, and in cases where non-interpenetrating,
guest-stabilized open frameworks have been obtained,
the three-dimensional frameworks often collapse upon
removal of the enclosed molecules. In our own work,
we have encountered a related case in a one-dimen-
sional solid that illustrates the stereochemical ‘non-
rigidity’ of a frequently used intermolecular link, the
metal–nitrile bond [4a,c]. Thus in the construction of
open three-dimensional networks by molecular self-as-
sembly, the ‘weak’ directional intermolecular links are
not only an essential tool in achieving spatial organi-
zation, but also the root of intrinsic difficulties. In
view of this situation, we are considering an alterna-
tive approach towards the synthesis of molecular ma-
terials with zeolite-like structures that is perhaps more
1. Introduction
Isocyanide metal complexes [1] bearing donor
groups in peripheral locations can undergo molecular
self-assembly [2] with unsaturated metal complexes or
metal ions to form coordination polymers [3,4]. De-
pending on the spatial arrangement of the donor
groups, the isocyanide metal complexes may be de-
signed to serve as building blocks for one-, two-, and
three-dimensional solids. With square planar and oc-
tahedral building blocks, one might expect the forma-
tion of two and three-dimensional solids with open
structural networks. However, open frameworks are
not easily obtained by molecular self-assembly. The
difficulties arise from the need to establish the inter-
molecular links under reversible conditions. The ther-
modynamically stable solid-state structures resulting
* Corresponding author. Tel.: +1-516-6327951; fax: +1-516-
6327960.
E-mail address: amayr@notes.cc.sunysb.edu (A. Mayr)
1 Present address: Department of Chemistry, Peking University,
Beijing, People’s Republic of China.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00185-0

L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
27
cumbersome, but ultimately more practical, namely
2.1. 4,4%-Bis(3,5-diisopropyl-4-formamidophenylethynyl)
biphenyl
the covalent construction of robust open molecular
structures from geometrically well-defined structural
subunits. Since covalent molecular structures are inca-
pable of complete mutual interpenetration, their com-
bination into larger assemblies or extended solids
would necessarily give rise to materials with zeolite-
like properties. With the rectangular geometry of iso-
cyanide metal complex building blocks, an obvious
route to robust open molecular structures could be
based on the covalent linkage of square and cube
corner units [7]. With this alternative strategy to open
molecular structures in mind, we have synthesized
several cis-diisocyanide and fac-triisocyanidemetal
complexes featuring terminal functionalities capable of
forming strong coordinative or covalent intermolecu-
lar bonds.
2,6-Diisopropyl-4-iodo-formamidobenzene (1.40 g,
4.23 mmol), copper(I) iodide (0.130 g, 0.682 mmol)
and
bis(triphenylphosphine)palladium
dichloride
(0.208 g, 0.296 mmol) are added to a flask. Then,
THF (20 ml), triethylamine (80 ml), and 4,4%-di-
ethynylbiphenyl (0.432g, 2.14 mmol) are added. The
mixture is stirred at 60–70°C for 17 h. After the
reaction is complete (monitored by TLC), the result-
ing mixture is filtered through a plug of silica gel and
washed with dichloromethane. The combined filtrates
are washed with water and dried over magnesium sul-
fate. After evaporation of the solvent, the product is
obtained as a pale yellow solid, which is recrystallized
from n-hexane (1.158 g, 89%). 1H-NMR (CDCl3),
several isomers: l 8.50 (s, 1 H), 8.06-8.02 (d, 1 H),
7.64–7.62 (2 d, 8 H, C6H4), 7.39 (s, 4 H, C6H2),
6.88–6.83 (d, 1 H), 6.71 (s, 1 H), 3.23–3.09 (m, 4 H,
J=6.8 Hz, CH); 1.26–1.24 (d, 24 H, J=6.8 Hz,
CH3). 13C-NMR (CDCl3), several isomers: l 164.7,
160.3 (NHCHO), 147.0, 146.6, 140.3, 140.2, 140.1,
140.0, 139.1, 132.2, 132.2, 130.6, 130.1, 130.1, 129.9,
127.4, 127.1, 127.0, 126.9, 123.9, 123.8, 123.7, 123.7,
122.6, 122.6, 122.4, 122.3, 90.6, 90.5, 90.1, 90.1, 89.7,
89.7, 89.2, 89.2(–CC–), 28.9, 28.5 (CH), 23.5, 23.5
(CH3). IR (CH2Cl2, cm−1): w(NHCHO)=1697. MS
(m/z, rel. int.): 608 (35%, M).
2. Experimental
The isocyanides 1–5 [4d,8], 2,6-diisopropyl-4-iodo-
formamidobenzene [8], and 4,4%-diethynylbiphenyl [9],
W(CO)3(NCCH3)3 [10], W(h6-C7H8)(CO)3 [11], Re-
Cl(CO)3(THF)2 [12], and Fe(h5-C5H5)Cl(CO)2 [13]
were prepared as described in the literature. THF,
ether, CH2Cl2, and n-hexane were distilled under N2
from appropriate drying agents. All other solvents
and reagents were of analytical grade and were used
as received, unless otherwise noted. The syntheses of
the transition metal complexes were performed under
an atmosphere of N2. The NMR spectra were
recorded at 300 MHz for 1H-NMR and 75.4 MHz
for 13C-NMR. The elemental analyses were performed
by Butterworth Laboratories.
2.2. 4,4%-Bis(3,5-diisopropyl-4-isocyano-phenylethynyl)
biphenyl (6)
6
1
Triphosgene (0.300 g/10 ml THF) is added slowly
to a frozen THF solution of 4,4%-bis(3,5-diisopropyl-4-
formamidophenylethynyl)biphenyl (0.60 g, 0.987
mmol) and triethylamine (0.85 ml) at −198°C. The
mixture is slowly warmed to room temperature (r.t.)
and stirred for 11 h. Then an aqueous solution of
sodium carbonate (10%, 40 ml) is added, and the
mixture is stirred for another hour. The THF is re-
moved under reduced pressure. After adding more
water, the resulting mixture is extracted with
dichloromethane. The organic layer is washed with
water and dried over magnesium sulfate. After evapo-
ration of the solvent, the product is obtained as a
2
3
4
5
1
light yellow solid (0.495 g, 87.7%). H-NMR (CDCl3):
l 7.65–7.64 (s, 8 H, C6H4), 7.35 (s, 4 H, C6H2),
3.41–3.36 (m, 4 H, CH), 1.33–1.30 (d, 24 H, CH3).
13C-NMR (CDCl3): l 170.0 (CN), 145.3, 140.3, 132.2,
127.0, 126.7, 124.3, 122.2, 90.8 (–CC–), 89.9 (–CC–),

28
L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
29.8 (CH), 22.5 (CH3). IR (CH2Cl2, cm−1): w(CN)=
2118. MS (m/z, rel. int.): 573 (M+1, 70%).
J=6.8 Hz, CH), 3.21 (s, 2 H, CC–H), 1.30–1.28 (d,
24 H, CH3). 13CNMR (CDCl3): l 186.5 (CO), 183.8
(CO), 150.4, 146.1, 127.5, 124.0, 82.8, 79.6, 30.0, 22.3.
IR (CH2Cl2, cm–1): w(CC–H)=3298 (m); w(CN)=
2179 (vw), 2146 (w); w(CO)=2039 (vs), 1992 (s), 1931
(s). FAB-MS (m/z, rel. int.): 729 (10%, M+1), 694
(85%, M–Cl+1), 673 (100%, M–2CO+1).
2.3. cis-W(4-CN-3,5-i-Pr2–C6H2CC-4-C5H4N)2(CO)4
(7)
7
2.5. Fe(p5-C5H5)Cl(4-CN-3,5-i-Pr2–C6H2CCSiMe3)2
(9)
W(CO)3(NCCH3)3 (55.0 mg, 0.138 mmol) is added
to a solution of 5 (70.0 mg, 0.243 mmol) in THF (7
ml). The solution is stirred at r.t. for about 18 h.
During this time the orange solution changes to red
brown. Then THF is removed under reduced pressure.
The solid residue is purified by chromotograpy on
silica gel using 5:1 ethyl acetate–n-hexane as the elu-
ent. The product is obtained as a brown–yellow solid
(40.8 mg, yield: 38.5%). The single crystal for the
X-ray crystallographic study was obtained by evapo-
rating a solution of 7 in acetone very slowly at r.t.
Found: C, 58.82; H, 4.62; N, 6.07. Calc. for
C44H40N4O4W.1.5 H2O, FW: 872.62+27.02 (899.65):
9
A solution of 3 (102 mg, 0.36 mmol) and Fe(h5-
C5H5)Cl(CO)2 (37 mg, 0.187 mmol) in THF (8 ml) is
stirred at r.t. for 40 h. The color of the solution
changed to brown. When the reaction is complete
(monitored by IR), the solvent is removed under re-
duced pressure. The solid residue is recrystallized from
dichloromethane–n-hexane. Two components are ob-
tained: A brown solid, 9, (20 mg, yield: 15%) and a
pale yellow solid, 18, (33 mg, yield: 26%), which is the
less soluble product. 9: Found: C, 67.72; H, 7.61; N,
3.91%. Calc. for C41H55N2Si2FeCl, FW: 723.32: C,
1
C, 58.74; H, 4.82; N, 6.23. H-NMR (CDCl3): l 8.63–
8.61 (m, 4 H, C5H4N), 7.40–7.39 (m, 4 H, C5H4N),
7.34 (s, 4 H, C6H2), 3.34–3.19 (m, 4 H, J=6.7 Hz,
CH), 1.33–1.31 (d, 24 H, J=6.9 Hz, CH3). 13C-NMR
(CDCl3): l 198.7 (CO), 196.0 (CO), 147.8, 146.2,
145.6, 145.5, 144.7, 143.8, 127.6, 127.4, 127.2, 126.6,
126.2, 121.6, 87.8, 87.6, 30.2, 29.9, 29.6, 22.6, 22.5,
22.1. IR (CH2Cl2, cm−1): w(CN)=2135 (m), 2073 (s);
w(CO)=2008(s), 1940 (sh), 1929 (vs). FAB-MS (m/z,
rel. int.): 873 (30%, M+1), 845 (32%, M–CO+1),
817 (38%, M–2CO+1), 289 (82%, L+1).
1
68.08; H, 7.66; N, 3.87%. H-NMR (CDCl3): l 7.26 (s,
4 H, C6H2), 4.76 (s, 5 H, C5H5), 3.50–3.40 (m, 4 H,
J=6.8 Hz, CH), 1.28–1.25 (d, 24 H, J=6.9 Hz,
CH3), 0.28 (s, 18 H, SiMe3). 13C-NMR (CDCl3): l
181.4 (CN), 144.9, 127.3, 127.1, 122.4, 104.8, 95.7,
81.1, 29.8, 22.6, 0.1. IR (CH2Cl2, cm−1): w(CN)=
2120 (s), 2073 (s). FAB-MS (m/z, rel. int.): 688 (20%,
M–Cl), 439 (15%, M–L), 404 (100%, M–L–Cl).
2.4. cis-ReCl(4-CN-3,5-i-Pr2–C6H2CCH)2(CO)3 (8)
2.6. Fe(p5-C5H5)Cl(4-CN-3,5-i-Pr2–C6H2CCH)2 (10)
10
8
ReCl(CO)5 (53.0 mg, 0.147 mmol) is dissolved in
THF (15 ml) and refluxed for 12 h (monitored by IR).
The resulting solution is then cooled to r.t., and 4
(62.0 mg, 0.294 mmol) is added. The mixture is stirred
at r.t. for 24 h (monitored by IR). After removing the
solvent, the solid residue is recrystallized from
dichloro-
methane–n-hexane. The product is obtained as a
brown–yellow solid (51.0 mg, 47.8%). Single crystals
suitable for X-ray crystallography were obtained by
evaporating a solution of 8 in CH2Cl2 slowly at r.t.
Found: C, 54.97; H, 5.08, N, 3.58%. Calc. for
C33H34N2O3ReCl.0·2 C6H14, FW: 728.27+17.23
(745.50): C, 55.10; H, 4.98; N, 3.76. 1H-NMR
(CDCl3): l 7.32 (s, 4 H, C6H2), 3.38–3.28 (m, 4 H,
The procedure described for 9 is followed. 4 (194
mg, 0.919 mmol), Fe(h5-C5H5)Cl(CO)2 (90 mg, 0.424
mmol), THF (20 ml), reaction time 16 h. Two prod-
ucts are obtained, a red solid, 10, (20 mg, yield: 8.2%)
and a deep brown solid, 19, (168 mg, yield: 69.5%),
which is the less soluble product. These two complexes
are purified by chromatography on silica gel using 2:1
ethyl acetate–n-hexane for 10 and methanol for 19 as
the eluents. 10: Found: C, 72.33; H, 6.59; N, 5.20%.
Calc. for C35H39N2FeCl, FW: 579.02: C, 72.63; H,
1
6.74; N, 4.84%. H-NMR (CDCl3): l 7.29 (s) and 7.26
(s) (4 H, C6H2), 4.76 (s, 5 H, C5H5), 3.6–3.3 (m, 4 H,
CH), 3.16 (s, 2 H, CC–H), 1.29–1.25 (d, 24 H, CH3).
13C-NMR (CDCl3): l 181.7 (CN), 145.0, 127.6, 127.3,
121.4, 83.4, 81.1, 78.4, 29.8, 22.6, 22.5. IR (CH2Cl2,

L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
29
cm−1): w(CC–H)=3300 (m); w(CN)=2124 (s), 2073
(s). FAB-MS (m/z, rel. int.): 579 (20%, M+), 544
(40%, M–Cl), 367 (100%, FeLCl), 332 (95%, FeL-1).
1302 (M+1), 1267 (M−Cl+1), 729 (M–L+1), 694
(100%, M–L–Cl+1), 572 (L).
2.9. fac-W(CN-2,6-i-Pr2–C6H2-4-Br)3(CO)3 (13)
2.7. Fe(p5-C5H5)Cl(4-CN-3,5-i-Pr2–C6H2CC-4-C5H4-
N)2 (11)
13
A solution of 1 (273 mg, 1.03 mmol) and W(h6-
C7H8)(CO)3 (124 mg, 0.342 mmol) in THF (10 ml) is
stirred at r.t. for 6 h (monitored by IR). The color of
the solution changes to orange–yellow. The solvent is
removed under reduced pressure, and the solid residue
is recrystallized from n-hexane to afford an orange
yellow crystalline solid (180 mg, yield 49%). Found: C,
48.92; H, 4.90; N, 4.15%. Calc. for C42H48N3O3Br3W·1/
2C6H14 FW: 1066.37+43.08 (1109.45): C, 48.71; H,
5.00; N, 3.79%. 1H-NMR (CDCl3): l 7.25 (s, 6 H,
C6H2), 3.34–3.24 (m, 6 H, J=6.8 Hz, CH), 1.26–1.23
(d, 12 H, J=6.8 Hz, CH3). 13C-NMR (CDCl3): l 201.4
(CO), 165.4 (CN), 146.7, 126.8, 125.3, 123.3, 122.2,
30.2, 22.3. IR (CH2Cl2, cm−1): w(CN)=2134 (w), 2058
(s); w(CN)=1942 (s), 1896 (s). FAB-MS (m/z, rel. int.):
1068 (1064) (100%, M+1), 1040 (1036) (82%, (M−
CO+1).
11
A solution of 6 (104 mg, 0.36 mmol) and Fe(h5-
C5H5)Cl(CO)2 (38.9 mg, 0.18 mmol) in THF (25 ml) is
stirred at r.t. for 36 h. After the reaction is complete
(monitored by IR), the solvent is removed under re-
duced pressure. The solid residue is recrystallized with
dichloromethane–n-hexane. The product is isolated as
a red–brown crystalline solid (55.6 mg, yield 41.2%).
Single crystals of 11 suitable for X-ray crystallography
were obtained by slow evaporation of a solution of 11
in a mixture of dichloromethane and n-hexane. Found:
C, 71.64; H, 6.41; N, 7.67%. Calc. for C45H45N4-
ClFe.H2O, FW: 733.13+18.01 (751.14): C, 71.95; H,
1
6.31; N, 7.46%. H-NMR (CD2Cl2): l 8.60–8.58 (m, 4
H, C5H4N), 7.41–7.37 (m, 8 H, C5H4N, C6H2), 4.80–
4.78 (s, 5 H, C5H5), 3.54–3.45 (m, 4 H, J=6.8 Hz,
CH), 1.32–1.29 (d, 24 H, J=6.8 Hz, CH3). 13C-NMR
(CDCl3): l 182.3 (CN), 150.0,149.9, 145.3, 145.3, 131.1,
130.6, 127.4, 127.1, 125.5, 121.5, 93.6 (–CC–), 87.9
(–CC–), 81.3 (C5H5), 29.9 (CH), 22.6 (CH3). IR
(CH2Cl2, cm−1): w(CN)=2120 (s), 2071 (s). FAB-MS
(m/z, rel. int.): 731 (18%, M−1).
2.10. fac-W(CN-2,6-i-Pr2–C6H2-4-I)3(CO)3 (14)
14
2.8. Fe(p5–C5H5)Cl(4-(4-CN-3,5-i-Pr2–C6H2CC)–C6-
H4–C6H4-4%-(CCC6H2-2,6-i-Pr2-4-NC))2 (12)
This complex is obtained following the procedure
described for complex 13. 2 (280 mg, 0.894 mmol),
W(h6-C7H8)(CO)3 (90 mg, 0.248 mmol), THF (10 ml).
Orange yellow solid (65 mg, yield: 22%). Found: C,
42.55; H, 4.01; N, 3.65%. Calc. for C42H48N3O3I3W,
1
FW: 1207.37: C, 44.78; H, 4.01; N, 3.48%. H-NMR
(CDCl3): l 7.44 (s, 6 H, C6H2), 3.34–3.24 (m, 2 H, CH,
J=6.8 Hz), 1.26–1.23 (d, 12 H, CH3, J=6.8 Hz).
13C-NMR (CDCl3): l 201.4 (CO), 165.6 (CN), 146.7,
132.8, 126.0, 94.11, 30.1, 22.3. IR (CH2Cl2, cm−1):
w(CN)=2131 (vw), 2058 (s); w(CO)=1942 (s), 1900 (s).
FAB-MS (m/z, rel. int.): 1208 (90%, M+1).
12
This complex is prepared following the procedure
described for 9. 7 (66 mg, 0.115 mmol), Fe(h5-
C5H5)Cl(CO)2 (9 mg, 0.042 mmol), THF (23 ml), reac-
tion time 90 h (r.t.). The product is isolated as a yellow
solid. Found: C, 74.30; H, 6.01; N, 3.53. Calc. for
C89H85N4ClFe·2CH2Cl2, FW:1301.89+169.86 (1471.
2.11. fac-W(4-CN-3,5-i-Pr2–C6H2CCH)3(CO)3 (15)
1
75): C, 74.26; H, 6.10; N, 3.81%. H-NMR (CD2Cl2): l
7.66 (br, 16 H, C6H4), 7.45–7.37 (br, 8 H, C6H2),
4.80–4.78 (d, 5 H, C5H5); 3.62–3.38 (m, 8 H, CH);
1.36–1.21 (48 H, CH3). 13C-NMR (CDCl3): l 181.7
(NC), 146.9, 146.5, 145.2, 145.1, 140.4, 140.2, 133.1,
132.3, 132.2, 127.3, 127.0, 126.9, 126.8, 90.6, 90.3, 81.2,
80.1, 29.9 (CH), 22.7, 22.6 (CH3). IR (CH2Cl2, cm−1):
w(CN)=2118 (s), 2070 (s). FAB-MS (m/z, rel. int.):
15
This complex is obtained following the procedure
described for 13. 4 (337 mg, 1.60 mmol), W(h6-

30
L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
C7H8)(CO)3 (190 mg, 0.523 mmol), THF (15 ml), reac-
tion time 13 h. The product is a deep brown solid (56 mg,
yield: 11.9%). H-NMR (CDCl3): l 7.28 (s, 6 H, C6H2),
2.14. [Fe(p5-C5H5)(4-CN-3,5-i-Pr2–C6H2CCSiMe3)3]
Cl (18)
1
3.57–3.30 (m, 6 H, CH), 3.16 (s, 3 H, CC–H), 1.29–1.23
(d, 36 H, CH3). IR (CH2Cl2, cm−1): w(CC)=3298 (m);
w(CN)=2131 (w), 2054 (s); w(CO)=2009 (m), 1940 (s),
1902 (s). MS (m/z, rel. int.): 902 (45%, M+1), 874 (65%,
M–CO+1), 816 (70%, M–3CO−1).
18
This compound was obtained as a by-product of the
synthesis of 9, as described above. Found: C, 62.39; H,
7.24; N, 3.83%. Calc. for C59H80ClFeN3Si3·FeCl(OH)2,
FW: 1006.80+125.31 (1132.11): 62.59; H, 7.30; N,
3.71%. IR (CH2Cl2, cm-1): w(CN)=2162 (m), 2116 (s).
FAB-MS (m/z, rel. int.): 971 (40%, M–Cl+1), 688
(15%, M–Cl–L+1), 404 (100%, M–Cl–2L).
2.12. fac-W(4-CN-3,5-i-Pr2–C6H2CC-4-C5H4N)3(CO)3
(16)
16
A solution of W(h6-C7H8)(CO)3 (86.0 mg, 0.237
mmol) and 6 (0.210 g, 0.729 mmol) in THF is stirred at
r.t. for 48 h. After the reaction is complete (monitored
by IR), the solvent is removed under reduced pressure.
The solid residue is purified by chromatography on silica
gel using 1:2 ethyl acetate–n-hexane as the eluent. Three
complexes are obtained: 7 (12 mg, yield: 11.6%), 21 (72
mg, yield: 49.7%), 16 (25 mg, yield: 27.9%). 16: Found:
C, 69.35; H, 6.29; N, 6.27%. Calc. for
C63H60N6O3W·2C6H14, FW: 1132.98+172.34 (1305.32):
C, 69.01; H, 6.79; N, 6.44%. 1H-NMR (CDCl3): l
8.64–8.61 (m, 6 H, J=4.4, 1.5 Hz, C5H4N), 7.42–7.31
(m, 12 H, C5H4N, C6H2), 3.43–3.28 (m, 6 H, CH),
1.32–1.23 (m, 36 H, CH3). IR (CH2Cl2, cm−1): w(CC)=
2216 (vw), w(CN)=2129 (vw), 2118 (vw), 2052 (s),
w(CO)=1942 (s), 1904 (s). FAB-MS (m/z, rel. int.): 1137
(M+5).
2.15. [Fe(p5-C5H5)(4-CN-3,5-i-Pr2–C6H2CCH)3] Cl
(19)
19
This compound was obtained as a by-product of the
synthesis of 10, as described above. 19: 1H-NMR-
(CDCl3): l 7.29 (s, 6H, C6H2), 4.76 (s, H, C5H5), 3.23 (s,
3 H, CCH), 3.20–3.10 (m, 6 H, J=6.8 Hz, CH),
1.29–1.22 (d, 36 H, J=6.8 Hz, CH3). 13C-NMR
(CDCl3): l 145.0, 127.7, 123.7, 84.9, 82.6, 79.9, 30.2,
22.4. IR (CH2Cl2, cm−1): w(CC–H)=3298 (m);
w(CN)=2164 (m), 2118 (s). FAB-MS (m/z, rel. int.): 755
(40%, M–Cl+1), 544 (M–Cl–L+1), 367 (M–2L), 332
(100%, M–Cl–2L).
2.13. [Fe(p5-C5H5)(CN-2,6-i-Pr2–C6H2-4-I)3] Cl (17)
2.16. [Fe(p5-C5H5)(4-CN-3,5-i-Pr2–C6H2CC-4-C5H4-
N)3] Cl (20)
17
A solution of 2 (117 mg, 0.373 mmol) and Fe(h5-
C5H5)Cl(CO)2 (39.7 mg, 0.187 mmol) in THF (10 ml) is
stirred for 36 h under nitrogen. After removing the
solvent under reduced pressure, the solid residue is
recrystallized from methylene chloride–n-hexane. The
product is obtained as a pale yellow crystalline solid (27
mg, yield: 20%). Found: C, 46.46; H, 5.11; N, 3.99%.
Calc. for C44H53N3I3FeCl·2H2O, FW: 1095.89+36.02
(1131.91): C, 46.69; H, 5.08; N, 3.71%. 1H-NMR
(CDCl3): l 7.48 (s), 7.26 (s), 5.50 (s), 4.75 (s), 3.42 (br),
3.15 (br), 1.27 (s). 13C-NMR (CDCl3): l 172.3 (CN),
147.0, 133.9, 126.6, 97.0, 95.0, 33.6, 26.7. IR (CH2Cl2,
cm−1): w(CN)=2164 (s), 2120 (s). FAB-MS (m/z, rel.
int.): 1061 (100%, M–Cl+1).
20
This complex was obtained following the procedure
described for 17, using 6 (87.9 mg, 0.305 mmol) and
Fe(h5-C5H5)Cl(CO)2 (21.6 mg, 0.102 mmol). The
product is a pale yellow solid (40.7 mg, 39%). Found: C,
70.93; H, 6.24; N, 7.43. Calc. for C65H65N6ClFe·4H2O.
FW 1021.50+72.04 (1093.54: C, 71.39; H, 6.73; N, 7.69.
1H-NMR (CDCl3): l 8.64 (m, 6 H, C5H4N); 7.40 (m, 6H,
C5H4N), 7.36 (s, 6 H, C6H2); 4.80 (s, 5 H, C5H5);
3.53–3.48 (m, 6 H, J=6.3 Hz, CH); 1.32–1.29 (d, 36 H,
J=6.4 Hz, CH3). IR (CH2Cl2, cm−1): w(CN)=2162
(m), 2118 (s), 2071 (w). FAB-MS (m/z, rel. int.): 986
(10%, M–Cl+1), 409 (100%, M–Cl–2L).

L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
31
2.17. W(4-CN-3,5-i-Pr2–C6H2CC-4-C5H4N)(CO)5 (21)
using X-ray radiation from an MAR generator (sealed
tube 50 kV and 50 mA), and processed by DENZO [14].
The X-ray radiation from both generators was
graphite-monochromatized Mo–Ka X-ray radiation
,
(u=0.71073 A). Empirical absorption corrections from
21
c-scans were applied to the data for compounds 7 and
11, and no absorption correction was made on com-
pound 8. All structure determinations and numerical
calculations were done using the MSC crystal structure
analysis package TEXSAN [15] using a Silicon Graphics
Computer, and the full-matrix least squares refinements
were on F using reflections with I\3|(I). Hydrogen
atoms at calculated positions with thermal parameters
equal to 1.3 times that of the attached C atoms were
included in the calculations, but not refined.
This compound was obtained as a by-product of the
1
synthesis of complex 16, as described above: H-NMR
(CDCl3): l 8.64–8.62 (m, 2 H, C5H4N), 7.41–7.39 (m,
2 H, C5H4N), 7.35 (s, 2 H, C6H2), 3.43–3.34 (m, 2 H,
J=6.9 Hz, CH), 1.32–1.30 (d, 12 H, J=6.8 Hz, CH3).
13C-NMR (CDCl3): l 193.7 (CO), 170.7 (CN), 149.9,
145.5, 131.0, 127.3, 127.0, 125.5, 123.2, 93.1, 88.1, 29.9,
22.5. IR (CH2Cl2, cm−1): w(CC)=2218 (vw), w(CN)=
2118 (s), w(CO)=2054 (m), 1952 (vs). FAB-MS (m/z,
rel. int.): 612 (M), 584 (M–CO), 289 (100%, L+1).
3. Results and discussion
2.18. X-ray crystallographic studies
The isocyanides 1–5 have been prepared as previ-
ously described [4d,8]. The diisocyanide 6 was synthe-
sized by palladium-catalyzed cross-coupling [16] of
4,4%-diethynylbiphenyl with 2,6-diisopropyl-4-iodo-for-
mamidobenzene, followed by dehydration of the for-
mamide groups with triphosgene/triethylamine [17].
With a selection of these isocyanides, several cis-diiso-
cyanide metal complexes of tungsten [18], rhenium [19],
The diffraction data for compounds 7 and 11 were
collected on a Rigaku AFC7R four-circle diffractome-
ter using X-ray radiation from a Rigaku RU-200 rotat-
ing-anode generator at 50 kV and 160 mA and
processed by the MSC/Rigaku diffractometer control
software. The diffraction data for compound 8 were
collected on an MAR Imaging Plate Detector System
Table 1
Crystal and data collection parameters for complexes 7, 8, and 11
7
8
11
Formula
C44H40N4O4W
C33H34ClN2O3Re
728.30
C45H45ClFeN4
733.18
Formula weight
Crystal system
Space group
872.67
Monoclinic
P21/c (no. 14)
10.908(4)
17.509(4)
21.229(6)
90.26(3)
4054(1)
4
Monoclinic
C2/c (no. 15)
29.707(4)
10.022(2)
21.845(3)
93.52(2)
6491(1)
Orthorhombic
Pnma (no. 62)
11.715(3)
34.871(5)
10.016(3)
90.00
,
a (A)
,
b (A)
,
c (A)
i (°)
3
,
V (A )
4091(1)
4
Z
8
T (K)
301
301
301
Crystal color
Red
Yellow
0.25×0.20×0.10
1.420
Brown
0.15×0.05×0.30
1.190
Crystal dimensions (mm)
0.20×0.15×0.25
1.430
28.98
dcalc. (g cm−3
)
v (cm−1
)
38.61
4.68
Scan mode
2qmax (°)
ꢀ−2q
50.0
ꢀ−2q
50.0
51.1
Unique reflections
7395
6141
4097
Reflections (I\3|(I)) used in LS refinement
4949
4191
1972
Number of variables
R
wR
(Z/|)max
478
361
235
0.029a
0.034a
0.047b
0.02
0.054a
0.035b
0.05
0.058b
0.01
Goodness-of-fit
1.38
−0.36/0.75
1.69
−1.90/0.38
2.23
−0.35/0.42
−3
,
Dz (e A
)
a R=S ꢀꢀ Fo ꢀ−ꢀ Fc ꢀꢀ/S ꢀ Fo ꢀ.
b wR=[S w(ꢀ Fo ꢀ−ꢀ Fc ꢀ)2/S wFo2]1/2, where w=Fo2/[|2(I)+(pF2o)2].

32
L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
Table 2
ilarly the cationic triisocyanide iron complex 17 was
obtained in low yield by reaction of Fe(h5-C5H5)Cl(CO)2
with two equivalents of 2. In this case, the diisocyanide
iron complex was not isolated. The triisocyanide tung-
sten complexes [18] 13–16 were obtained in low to
moderate yield by reaction of W(h6-C7H8)(CO)3 with the
respective isocyanides 1, 2, 4, and 5 in THF, followed by
chromatography on silica gel. In the reaction of W(h6–
C7H8)(CO)3 with three equivalents of 5, not only the
triisocyanide tungsten complex 16 formed, but also the
diisocyanide complex 7 and the monoisocyanide tungsten
complex [18] 21.
,
Selected bond lengths (A) and bond angles (°)
(a) Complex 7
W(1)–C(1)
W(1)–C(3)
W(1)–C(5)
N(1)–C(5)
N(2)–C(25)
C(12)–C(13)
2.000(6)
2.026(7)
2.113(5)
1.153(6)
1.153(6)
1.167(7)
W(1)–C(2)
W(1)–C(4)
W(1)–C(25)
N(1)–C(6)
N(2)–C(26)
C(32)–C(33)
2.004(6)
2.049(7)
2.116(5)
1.401(6)
1.401(6)
1.173(7)
C(1)–W(1)–C(2) 90.1(2)
C(2)–W(1)–C(5) 88.2(2)
W(1)–C(5)–N(1) 175.3(4)
C(5)–N(1)–C(6) 174.2(5)
C(1)–W(1)–C(25)
C(5)–W(1)–C(25)
W(1)–C(25)–N(2) 172.9(5)
C(25)–N(2)–C(26) 172.9(5)
88.1(2)
93.7(2)
(b) Complex 8
Re(1)–Cl(1)
Re1)–C(2)
Re(1)–C(4)
N(1)–C(4)
N(2)–C(19)
C(11)–C(12)
2.479(2)
Re(1)–C(1)
Re(1)–C(3)
Re(1)–Cl(19)
N(1)–C(5)
N(2)–C(20)
C(26)–C(27)
1.973(6)
1.977(5)
2.092(5)
1.146(6)
1.145(5)
1.163(9)
2.049(7)
2.079(5)
1.391(6)
1.397(6)
1.181(7)
C(1)–Re(1)–C(2) 91.2(2)
C(2)–Re(1)–C(4) 92.6(2)
Re(1)–C(4)–N(1) 174.3(4)
C(4)–N(1)–C(5) 173.2(5)
C(1)–Re(1)–C(19)
C(4)–Re(1)–C(19)
Re(1)–C(19)–N(2) 177.5(4)
C(19)–N(2)–C(20) 176.9(5)
90.4(2)
86.90(2)
(c) Compound 11
Fe(1)–Cl(1)
Fe(1)–C(2)
Fe(1)–C(4)
N(1)–C(5)
2.303(2)
Fe(1)–C(1)
Fe(1)–C(3)
N(1)–C(4)
C(17)–C(18)
2.109(8)
2.101(5)
1.817(5)
1.395(6)
2.069(5)
1.157(6)
1.183(7)
Cl(1)–Fe(1)–C(4) 89.9(3)
Fe(1)–C(4)–N(1) 176.9(4)
C(4)–Fe(1)–C(4*)
C(4)–N(1)–C(5)
94.9(3)
174.6(5)
and iron [20] have been prepared. The cis-diisocyanide(-
tetracarbonyl)tungsten complex 7 was obtained in 38%
yield as the major product in the reaction of a 1:2 mixture
of W(CO)3(NCMe)3 and 5 in THF. Evidently, some
decomposition of W(CO)3(NCMe)3 occurred during the
reaction, providing a source of carbon monoxide for the
formation of the tetracarbonyltungsten fragment. The
presence of W(CO)4(NCMe)2 as an impurity in
W(CO)3(NCMe)3 may also have contributed to the
formation of 7. Pure 7 was isolated after chromatography
on silica gel. The rhenium diisocyanide complex 8 formed
in 47% yield by reaction of ReCl(CO)3(THF)2 with
isocyanide 4. The iron complexes 9–12 were obtained in
low to moderate yield by reaction of Fe(h5-
C5H5)Cl(CO)2 with two equivalents of the respective
isocyanides 3–6. In the syntheses of the complexes 9–11,
the cationic triisocyanide iron complexes [20] 18–20 were
obtained as significant by-products. Owing to the large
difference in solubility between the neutral and cationic
iron complexes in organic solvents of low polarity, the
neutral complexes 9–11 were easily separated from the
cationic complexes 18–20 by recrystallization. Com-
plexes 19 and 20 are formulated as the chloride salts,
while complex 18 is tentatively formulated, based on
elemental analysis, as an adduct with ‘FeCl(OH)2’. Sim-
Fig. 1. Molecular structure of compound 7. The thermal ellipsoids are
shown at the 50% probability level.
Fig. 2. Molecular structure of compound 8. The thermal ellipsoids are
shown at the 50% probability level.

L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
33
adopts a roughly perpendicular orientation, and in 11,
both arene groups are oriented approximately perpen-
dicular to the Fe(CNAr)2 plane. Owing to the bulkiness
of the isopropyl substituents, the coplanar-perpendicu-
lar arrangement in the rhenium complex 8 is sterically
more favorable than either the coplanar-coplanar ar-
rangement of 7 or the perpendicular–perpendicular ar-
rangement of 11. Correspondingly, the RNC–M–CNR
bond angle in 8 (86.90(2)°) is smaller than in 7
(93.7(2)°) or 11 (94.9(3)°). The ‘outward’ bending of the
isocyanide ligands in 7 and 11, which is clearly visible
in Figs. 1 and 3, may be attributed to the steric
repulsions between the isopropyl groups of the adjacent
isocyanide ligands. At the locations of the ‘outer’
ethynyl carbon atoms, i.e. C(13) and C(33) for 7, C(12)
and C(27) for 8, and C(18) and C(18)* for 11, the
effects of these steric repulsions are amplified to the
extent that the interligand C–C separations of these
,
ethynyl carbon atoms differ by several Angstroms:
,
,
C(13)–C(33) in 7 is 16.2 A, C(12)–C(27) in 8 is 12.2 A,
,
and C(18)–C(18)* in 11 is 14.2 A long. Thus the
comparison of the three structures reveals a great deal
of intrinsic geometric flexibility in the cis-LnM(CNR)2
corner units owing to the combined effects of the
variable RNC–M–CNR bond angle and the bending
of the ‘linear’ extended isocyanide ligands.
Fig. 3. Molecular structure of compound 11. The thermal ellipsoids
are shown at the 40% probability level.
The cis arrangement of the two isocyanide ligands in
the complexes 7–11 is evident from the appearance of
two strong IR stretching frequencies for the CN triple
bonds [1]. The facial arrangement of the three iso-
cyanide ligands in the complexes 12–20 is also indi-
cated by the observation of two absorptions, one weak
and one strong. All metal complexes 7–20 give rise to
single sets of NMR signals for the isocyanide ligands,
although because of the presence of paramagnetic
iron(III), no well-resolved NMR spectra were obtained
for 18. For complexes 12–20, this observation is only
compatible with the facial arrangement of the three
isocyanide ligands.
The crystal structures of complexes 7, 8, and 11 have
been determined by X-ray crystallography. The crystal-
lographic information is collected in Table 1. Selected
bond distances and bond angles are listed in Table 2.
ORTEP drawings the molecular structures of 7, 8 and 11
are shown in Figs. 1–3. The structures confirm the cis
arrangement of the isocyanide ligands in all three struc-
tures. The intramolecular bond distances and bond
angles are within the expected range [1]. It is interesting
to note that the arrangements of the planes of the
isocyanide arene groups (C6H2-i-Pr2) in the molecules
7, 8, and 11 correspond to the three possible regular
arrangements in which the arene rings are either copla-
nar with or orthogonal to the M(CNR)2 plane. In 7,
both arene rings are almost coplanar with the W(C-
NAr)2 plane, in 8, one arene group is nearly coplanar
with the Re(CNAr)2 plane, while the other arene group
The isocyanides 4–6 contain functional groups which
are capable of forming strong coordinative bonds to
transition metal centers, namely ethynyl, 4-pyridyl, and
isocyanide groups. The ligands 1–4 may be covalently
connected in coupling and cross-coupling procedures
via the halo and alkynyl substituents. Transition metal
complexes of these isocyanides are therefore suitable to
serve as building blocks for robust large multimetallic
structures. In particular, the cis-diisocyanide metal
complexes, e.g. 6–7 and 9–12, could form the corners
of molecular squares and the fac-triisocyanide metal
complexes, e.g. 15–16 and 19–20 could form the cor-
ners of molecular cubes [7]. Owing to the strong bind-
ing sites and the long and slender shapes of the
isocyanides, two- and three-dimensional molecular
structures obtained from these building blocks could be
expected to be relatively rigid and open in character.
4. Supplementary material
Crystallographic data for the structure analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 114665–114667 for com-
pounds 7, 8, and 11. Copies of this information may be
obtained free of charge from the Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK. Fax. +44-
1223-336033, or E-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk.

34
L. Yang et al. / Journal of Organometallic Chemistry 585 (1999) 26–34
[6] (a) B.F. Abrahams, B.B. Hoskins, D.M. Michail, R. Robson,
Acknowledgements
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Support for this work by the Committee on Confer-
ence and Research Grants of The University of Hong
Kong and by the Hong Kong Research Grants Council
is gratefully acknowledged.
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