Inorg. Chem. 2010, 49, 3959–3961 3959
DOI: 10.1021/ic9025602
Stepwise Introduction of Thiolates in Copper-Indium Binuclear Complexes
Kelsey R. Margulieux,† Chivin Sun,† Lev N. Zakharov,‡ Andrew W. Holland,*,† and Joshua J. Pak*,†
†Department of Chemistry, Idaho State University, Pocatello, Idaho 83209, and ‡Department of Chemistry,
University of Oregon, Eugene, Oregon 97403
Received January 4, 2010
We report the synthesis and characterization of copper-indium
binuclear I-III complexes composing the series (Ph3P)2CuIn-
(SEt)xCl4-x (1-5; 0 e x e 4). Members of the series, which
are prepared by variations in the stoichiometry, are compared in
terms of their solid-state structures, spectroscopic features, and
suitability as precursors for CuInS2 materials. The regiochemistry of
thiolate substitution, the preference for monomeric versus dimeric
(eight-membered ring) structures, and new synthetic strategies
informed by this series are all discussed.
Many binuclear inorganic systems have attracted interest
for their unique magnetic,1 optical,2 and semiconducting
Figure 1. X-ray crystal structure of 1 with 30% probability thermal
ellipsoids depicted (H atoms are omitted for clarity). Selected bond
lengths are given in Table 1.
properties.3 We and others have been exploring the use of
copper-indium I-III complexes as molecular precursors for
CuInS2 nanoparticles.4,5 Although species of the form
(Ph3P)2Cu( μ-SR)2In(SR)2 show great promise for this
application, our own efforts to scale-up their preparation
using reported procedures encountered irreproducibility.
This challenge led us to revisit these syntheses, and in the
course of investigating new procedures, we have prepared
several novel species. Herein, we report the preparation and
characterization of complexes (Ph3P)2CuIn(SEt)xCl4-x, where
x varies from 0 to 4 as chlorides are replaced by thiolates across
the series. These complexes presented a unique opportunity to
study regiochemical selectivity and structural changes through
a sequence of substitution reactions at a binuclear center, and
their identification has informed the optimization of an im-
proved synthetic procedure for the tetrathiolate complex.
Reports by Hepp et al.5 and Hirpo et al.6 describe the
synthesis of (Ph3P)2Cu(μ-SEt)2In(SEt)2 by the addition of
copper complexes in CH3CN to methanolic Na[In(SEt)4]
generated in situ. Experiments with less polar solvents,
motivated by the hope that these might overcome limitations
in the generality and reproducibility of the original method,
revealed that the addition of (PPh3)2CuCl to InCl3 in benzene
at 80 °C results in dissolution of these independently inso-
luble materials. A soluble adduct was crystallized by slow
cooling and characterized, and analysis by X-ray crystal-
lography indicates that this complex exists in the solid state as
{(Ph3P)2Cu( μ-Cl)2InCl2}2 (1), a dimer of the anticipated
(Ph3P)2CuInCl4 formula featuring an eight-membered ring
of alternating Cu and In ions interspaced with chloride
ligands in a chairlike conformation (Figure 1).
*To whom correspondence should be addressed. E-mail: hollandr@
isu.edu (A.W.H.), pakjosh@isu.edu (J.J.P.).
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2010 American Chemical Society
Published on Web 04/07/2010
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