Synthesis and crystal structures of copper(I) iodide complexes chelating with bis(ethylamidophosphine)

Article abstract of DOI:10.1016/j.inoche.2003.09.003

Two copper(I) iodide complexes with polydentate bis(ethylamidophosphine) ligands were synthesized, characterized with crystal structures. They include a dimeric complex [Cu(μ-I)(CH₂NHCOC₂H₄PPh ₂)₂]₂ 1 containing a planar Cu ₂I₂ rhombohedron with two doubly bridged ligands and a tetrameric complex {Cu₄(μ-I)₄[(CH₂NHCOC ₂H₄PPh₂)₂]₂} 3 with all the coppers and iodines forming a highly distorted cubane geometry.

Full text of DOI:10.1016/j.inoche.2003.09.003

Inorganic Chemistry Communications 6 (2003) 1451–1453
www.elsevier.com/locate/inoche
Synthesis and crystal structures of copper(I) iodide
complexes chelating with bis(ethylamidophosphine)
*
Yat Li, Ka-Fu Yung, Hoi-Shan Chan, Wing-Tak Wong
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
Received 22 May 2003; accepted 1 September 2003
Published online: 7 October 2003
Abstract
Two copper(I) iodide complexes with polydentate bis(ethylamidophosphine) ligands were synthesized, characterized with crystal
structures. They include a dimeric complex [Cu(l-I)(CH2NHCOC2H4PPh2)2]2 1 containing a planar Cu2I2 rhombohedron with two
doubly bridged ligands and a tetrameric complex {Cu4(l-I)4[(CH2NHCOC2H4PPh2)2]2} 3 with all the coppers and iodines forming
a highly distorted cubane geometry.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Copper(I) iodide complex; Bis(ethylamidophosphine); Cubane; Crystal structure
In recent years the cuprous halide complexes have
drawn much attention. It is well known that these d10
complexes display rich coordination chemistry with a
great diversity of stoichiometries and geometries [1–5]
due to their relatively flat ground state potential energy
surfaces. Herein, we report the synthesis, crystal struc-
tures and the coordination chemistry of copper(I) iodide
complexes, [Cu(l-I)(CH2NHCOC2H4PPh2)2]2 1 and
{Cu4(l-I)4[(CH2NHCOC2H4PPh2)2]2} 3 from the reac-
tion Bis(ethylamidophosphine) [6] of with CuX. To our
knowledge, 3 is the first example of Cu4I4 cubane
complex bridging with a polydentate ligand, and its
electrochemical and photo-physical behavior is under
active investigation.
Single crystals were grown from their appropriate
solvent systems under favorable conditions. Intensity
data were collected at ambient temperature on a MAR
research image plate scanner using Mo-Ka radiation
and x scan technique. 60 Â 3° frames with an exposure
time of 3–15 min per frame were used. Crystallographic
data for the structures reported in this paper have been
deposited with the Cambridge Crystallograhic Data
Centre as supplementary publication no. CCDC
209664–209665. Copies of the data can be obtained free
of charge on application to CCDC, 12 Union Road,
Cambridge CB21EZ, UK (Fax: (+44)1223-336-033;
e-mail: deposit@ccdc.cam.ac.uk).
The synthesis of copper(I) iodide complexes are
summarized in Scheme 1. An ORTEP plot showing
the atomic-numbering scheme of 1 is depicted in
Fig. 1, together with the relevant bond lengths and
angles. The dimeric molecule contains two pseudotet-
rahedrally coordinated copper atoms bridged by two
iodine atoms. Each copper atom is further coordi-
nated with the phosphorus atoms of bis(ethylamido-
phosphine) ligand, which act as a bidentate bridge.
This kind of bridging structure is uncommon in cop-
per(I) iodide dimeric systems with bidentate ligands
[7]; more often each ligand binds to the one copper
atom owing to the great repulsion of the bridging
iodine atoms [8]. This molecule exhibits a planar
Cu2I2 rhombohedron, where the Cu–I [2.695(2) and
ꢀ
ꢀ
2.722(1) A] and Cu–P [2.262(2) and 2.256(2) A] bond
distances are comparable to the relevant bond lengths
observed in [CuI(C6H5PH2)2]2 [9] or [CuI{(C6H5)2
CH3P}2]2 [10]. However, it is noteworthy that the
extensively ligand bridged non-bonding CuÁ Á ÁCu
* Corresponding author. Tel.: +852-2859-2157; fax: +852-2547-2933.
E-mail address: wtwong@hkucc.hku.hk (W.-T. Wong).
ꢀ
[3.69 A] distance is significantly elongated, correspond-
1387-7003/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2003.09.003

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Y. Li et al. / Inorganic Chemistry Communications 6 (2003) 1451–1453
C
C
NH HN
PPh2
PPh2
Ph2P
Ph2P
X
X
CuX
Cu
Cu
X = I- or Br-
O
O
C
I
Ph2P
I
N
C
NH
Cu
PPh2
NH HN
C
C
H
O
O
HN
C
O
O
C
1
O
Cu
NH
C
C
I
Cu
Ph2P
N
N
Ph2P
PPh2
H
H
O
Bis(ethylamidophosphine)
Ph2P
Cu
I
3
O
O
C
C
NH HN
PPh2
PPh2
Ph2P
HgI2
CuI
I
I
I
Hg
C
Hg
I
Ph2P
NH HN
C
O
O
Scheme 1.
C(5)
C(4)
N(2)
ing to that observed in other dimeric copper(I) iodide
complexes [11–14]. Consequently, the relatively short
N(1)
C(6)
C(3)
O(2)
ꢀ
IÁ Á ÁI [3.96 A] bond distance and expanded Cu–I–Cu
C(7)
O(1)
C(2)
[85.94(6)°] angles are observed. This Cu2I2 rhombo-
hedron geometry probably minimizes the lengthening
effect of doubly bridging ligands, whilst keeping the
minimum iodine–iodine interaction.
C(10)
C(8)
C(1)
C(9)
C(16)
P(2*)
P(1)
I(1*)
The Hg(II) iodide complex [Hg(CH2NHCOC2H4
PPh2)2]2[I]4 2 was prepared according to a similar
synthetic method as 1, and fully characterized by
spectroscopic methods. It is interesting to note that
the reaction of 2 and CuI in dichloromethane at
ambient temperature affords Cu4I4 cubane complex
{Cu4(l-I)4[(CH2NHCOC2H4PPh2)2]2} 3 in a good
yield, however, the detailed mechanism of this reac-
tion is not yet clear. Fig. 2 shows the labeling scheme
for atoms in the molecule of 3. The most relevant
structural parameters are also reported. Four copper
and four iodine atoms, taken alternatively, define a
distorted cubane framework where each copper atom
is tetrahedrally coordinated with three l3-iodides and
a phosphorus atom of bis(ethylamidophosphine) li-
gand. Complex 3 is the first example of copper(I) io-
dide cubane complex bridging with a bidentate ligand.
C(15)
Cu(1*)
Cu(1)
C(22)
I(1)
C(21)
P(1*)
P(2)
C(27)
C(1*)
C(28)
Fig. 1. The molecular structure of [Cu(l-I)(CH2NHCOC2H4PPh2)2]2
1, with atom numbering scheme. The 30% probability thermal ellip-
ꢀ
soids are shown. Selected bond lengths (A) and angles (°):
Cu(1)ACu(1Ã) 3.69, I(1)AI(1Ã) 3.96, Cu(1)AI(1) 2.695(2), Cu(1)AI(1Ã)
2.722(1), Cu(1)AP(1) 2.262(2), Cu(1)AP(2) 2.256(2); Cu(1)AI(1)A
Cu(1Ã) 85.94(6), I(1)ACu(1)AI(Ã) 94.06(6), I(1)ACu(1)AP(1)
109.44(7), I(1)ACu(1)AP(2) 110.12(6), I(1Ã)ACu(1)AP(1) 111.19(6),
I(1Ã)ACu(1)AP(2) 107.53(7), P(1)ACu(1)AP(2) 121.13(8).
ꢀ
Both the Cu–I [range from 2.589(1) to 2.763(2) A] and
ꢀ
the Cu–P [2.252(3) and 2.266(3) A] bond distances are

Y. Li et al. / Inorganic Chemistry Communications 6 (2003) 1451–1453
1453
C(13*)
C(20)
P(1*)
O(1*)
O(2)
P(2)
I(1*)
I(2*)
N(1*)
N(2*)
C(17)
C(16)
C(14*)
C(19*)
C(15*)
C(18)
C(19)
Cu(1*)
Cu(2*)
I(2)
C(16*)
C(17*)
N(2)
N(1)
Cu(1)
C(18*)
C(15)
C(14)
C(13)
I(1)
Cu(2)
O(2*)
O(1)
P(1)
P(2*)
C(20*)
Fig. 2. The structure of {Cu4(l-I)4[(CH2NHCOC2H4PPh2)2]2} 3, with atom numbering scheme (phenyl rings and hydrogen aÃre omitted for clarity).
Ã
ꢀ
The 30% probability thermal ellipsoids are shown. Selected bond lengths (A) an angles (°): Cu(1)ACu(2) 2.88, Cu(1)ACu(1 ) 2.90, Cu(2)ACu(2 )
2.81, Cu(1)ACu(2Ã) 3.06, Cu(1)AI(1) 2.589(1), Cu(1)AI(1Ã) 2.763(2), Cu(1)AI(2) 2.709(2), Cu(2)AI(1) 2.705(2), Cu(2)AI(2) 2.619(2), Cu(2)AI(2Ã)
2.726(2), Cu(1)AP(1) 2.525(3), Cu(2)AP(2) 2.266(3), I(1)AI(2) 4.35, I(1)AI(2Ã) 4.33, I(1)AI(1Ã) 4.43, I(2)AI(2Ã) 4.48; Cu(1)AI(1)ACu(1Ã) 65.51(6),
Cu(1)AI(1)ACu(2) 65.91(5), Cu(1Ã)AI(1)ACu(2) 68.02(5), Cu(1)AI(1)ACu(2Ã) 65.45(4), Cu(1Ã)AI(1)ACu(2Ã) 68.50(5), Cu(2)AI(1)ACu(2Ã) 63.28(5).
closely similar to the corresponding values observed in
ꢀ
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