Synthesis, characterization, spectroscopic and photophysical properties of new [Cu(NCS){(L-N)2 or (L′-N∧N)}(PPh3)] complexes (L-N, L′-N∧N = Aromatic nitrogen base)

Article abstract of DOI:10.1002/ejic.200701236

The syntheses, spectroscopic characterization (IR, ¹H and ³¹P NMR, ESI-MS) and conductivity studies of the mixed N,P-donor complexes of copper(I) thiocyanate: [Cu(NCS)(py)₂-(PPh₃)], (2), [Cu(NCS)(Mepy)(PPh₃)]₂, (3), [Cu(NCS)(phen)- (PPh₃)], (4), [Cu(NCS)(bpy)(PPh₃)], (5), [Cu(NCS)(bpy)-(PPh₂py)], (6), [Cu(NCS)(py)(PPh₂py)], (7), (py = pyridine; Mepy = 2-methylpyridine; phen = 1,10-phenanthroline, bpy = 2,2′-bipyridyl), together with single-crystal X-ray structural characterizations of 2, 3, 4 (new polymorph), 5 and 6 are reported, which provides an opportunity to study the effect of the introduction of a pair of nitrogen donors, both unidentate and chelate, on the bonding parameters of the Cu/NCS/P system. Cu-P and Cu-N₂(ar) are found to be similar [2.1974(5) and 2.091(2), 2.070(1) A for py₂ adduct 2, cf. 2.1748(9)-2.200(1) and 2.071(2)-2.106(4) A for the counterpart values for bidentate adducts 4-6]. However, Cu-N(CS) and Cu-N-C are 2.013(2) A and 157.4(2)° for py₂ adduct 2 and 1.946(2)-1.981(8) A and 166.7(2)-176.58(2)° for bidentate counterparts 4-6. The change is attributed primarily to the closure in the N-Cu-N angle [99.58(8)° for py₂ 2; 77.7(6)-80.5(3)° for N∧N-bidentate donors 4-6]. In consequence of the increased steric profile of the Mepy ligand, we find the stoichiometry diminished to 1:1:1, which resulted in the formation of [(Ph₃P) MepyCu(_NCS^SCN)Cu(Mepy)(PPh₃)] dimers. TDDFT/CPCM calculations were used to clarify the type of transitions involved in the UV/Vis absorption spectra, and the corresponding experimental photoemission data were acquired. The ³¹P CPMAS spectra of the copper derivatives exhibit distorted quartets that afford values for ¹J_Cu,P. Furthermore, the quadrupole-induced distortion factors were calculated, and in the cases of 2, 4 and 5, the quadrupole coupling constants were obtained, on the basis of the X-ray structures. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200701236

FULL PAPER
DOI: 10.1002/ejic.200701236
Synthesis, Characterization, Spectroscopic and Photophysical Properties of
∧
∧
New [Cu(NCS){(L-N)2 or (LЈ-N N)}(PPh3)] Complexes (L-N, LЈ-N N =
Aromatic Nitrogen Base)
Claudio Pettinari,*[a] Corrado di Nicola,[a] Fabio Marchetti,[a] Riccardo Pettinari,[a]
Brian W. Skelton,[b] Neil Somers,[b] Allan H. White,[b] Ward T. Robinson,[c]
Michele R. Chierotti,[d] Roberto Gobetto,[d] and Carlo Nervi[d]
Keywords: Copper / Luminescence / N,P ligands / Structure elucidation / Electrochemistry
The syntheses, spectroscopic characterization (IR, 1H and 31
P
counterparts 4–6. The change is attributed primarily to the
closure in the N–Cu–N angle [99.58(8)° for py2 2; 77.7(6)–
80.5(3)° for N N-bidentate donors 4–6]. In consequence of
NMR, ESI-MS) and conductivity studies of the mixed N,P-
donor complexes of copper(I) thiocyanate: [Cu(NCS)(py)2-
(PPh3)], (2), [Cu(NCS)(Mepy)(PPh3)]2, (3), [Cu(NCS)(phen)-
(PPh3)], (4), [Cu(NCS)(bpy)(PPh3)], (5), [Cu(NCS)(bpy)-
(PPh2py)], (6), [Cu(NCS)(py)(PPh2py)], (7), (py = pyridine;
Mepy = 2-methylpyridine; phen = 1,10-phenanthroline, bpy
= 2,2Ј-bipyridyl), together with single-crystal X-ray structural
characterizations of 2, 3, 4 (new polymorph), 5 and 6 are re-
ported, which provides an opportunity to study the effect of
the introduction of a pair of nitrogen donors, both unidentate
and chelate, on the bonding parameters of the Cu/NCS/P
system. Cu–P and Cu–N2(ar) are found to be similar
[2.1974(5) and 2.091(2), 2.070(1) Å for py2 adduct 2, cf.
2.1748(9)–2.200(1) and 2.071(2)–2.106(4) Å for the counter-
part values for bidentate adducts 4–6]. However, Cu–N(CS)
and Cu–N–C are 2.013(2) Å and 157.4(2)° for py2 adduct 2
and 1.946(2)–1.981(8) Å and 166.7(2)–176.58(2)° for bidentate
∧
the increased steric profile of the Mepy ligand, we find the
stoichiometry diminished to 1:1:1, which resulted in the
formation of [(Ph3P)MepyCu(NSCCNS)Cu(Mepy)(PPh3)] dimers.
TDDFT/CPCM calculations were used to clarify the type of
transitions involved in the UV/Vis absorption spectra, and
the corresponding experimental photoemission data were
acquired. The 31P CPMAS spectra of the copper derivatives
1
exhibit distorted quartets that afford values for JCu,P
.
Furthermore, the quadrupole-induced distortion factors were
calculated, and in the cases of 2, 4 and 5, the quadrupole
coupling constants were obtained, on the basis of the X-ray
structures.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
found for the existence of the [CuX(py)2(PPh3)] series”,
seemingly still the case, although stabilization of the
[CuXN2P] motif by the use of the bidentate bpy (bpy =
2,2Ј-bipyridyl) ligand has been shown elsewhere.[6] The lat-
ter systems are mononuclear [CuX(bpy-N,NЈ)(PPh3)], X =
Cl, Br, I (isomorphous); the structures of monohydrates of
the chloride[7] and of the bromide[8] have also been re-
corded, as well as that of the N-thiocyanate/phenanthroline
(phen) counterpart.[9] The latter are consequent on an up-
surge of interest in the use of such systems as catalysts,[10]
as well as species with more complex, derivative ligands.
Very little work has been done on the counterpart silver(I)
systems, and the structure of [AgBr(phen)(PPh3)] is the only
example so defined.[11]
Further interest in such systems arises from the fact that
d10(I) complexes containing N-donor ligands exhibit a di-
verse variety of spectroscopic behaviours: luminescence
thermochromism, luminescence, solvatochromism, lumines-
cence rigidochromism and concentration luminochromism.
For example, a variety of trinuclear Cu pyrazolates[12] exhi-
biting fascinating optical phenomena and photolumines-
Introduction
Some years ago, from solutions of appropriate stoichi-
ometry of copper(I) halide, CuX (X = Cl, Br, I), tri-
phenylphosphane and pyridine (py) in acetonitrile, adducts
of stoichiometry CuX/PPh3/py (1:1:1 or 1:2:1) were crys-
tallized and characterized by single-crystal X-ray stud-
ies;[1–3] similar silver(I) counterparts were also defined.[4,5]
In ref.[1] the authors commented that “no evidence has been
[a] Dipartimento di Scienze Chimiche, Università degli Studi di
Camerino,
via S. Agostino 1, 62032 Camerino MC, Italy
Fax: +39-0737-637345
E-mail: claudio.pettinari@unicam.it
[b] Chemistry M313, School of Biomedical, Biomolecular and
Chemical Sciences, The University of Western Australia,
Crawley, WA 6009, Australia
[c] Department of Chemistry, University of Canterbury,
Christchurch, New Zealand
[d] Dipartimento di Chimica I.F.M., Università degli Studi di
Torino,
Via Giuria 7, 10125 Torino, Italy
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
1974
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1974–1984

∧
New [Cu(NCS){(L-N)2 or (LЈ-N N)}(PPh3)] Complexes
cent mixed-ligand copper polymers have been recently re- methylpyridine (Mepy) afforded derivative 3, but in this
ported.[13,14] Copper phosphino and/or pyridine deriva- case, presumably in consequence of the steric hindrance of
tives,[15–19] emissive at room or at low temperature, have the methyl group in the 2-position of the pyridine, which
been described but attempts to describe the associated spec- prevents the coordination of a second Mepy molecule about
troscopic properties in terms of known structures of the the copper atom, a compound with a 1:1:1 Cu/Mepy/PPh3
complexes remain limited. Despite the considerable atten- stoichiometry was obtained. In the IR spectra of 2 and 3,
tion paid to cyclic trinuclear d10 complexes, a fundamental the absorption bands of the NCS group fall at 2066 and
issue that remains outstanding concerns, for example, the 2095 cm–1, respectively. Whereas the former is mononuclear
role played by the transition metal in determining the mo- with an N-bonded NCS group, as also demonstrated in the
lecular structure, photophysics and spectroscopic properties X-ray structure (see below), the possibility that the latter
in mononuclear species. This paper reports the first system- exists as a dinuclear structure with a bridging Cu–NCS–Cu
atic effort, by combining a number of different techniques, system cannot be excluded, as confirmed by the X-ray
to unravel the role of the coinage metal and of the support- work. In the 1H NMR spectra of 2 and 3, the expected
ing ligands in determining the spectroscopic, structural and integration of the resonances for the presence of two py to
optical properties of a series of analogous mononuclear one PPh3 (derivative 2) ligand and a 1:1 Mepy/PPh3 ratio
MX(N2)P-type complexes.
(derivative 3) was observed. Variable temperature 31P NMR
In extending existing studies[1–3] to encompass the pseu- spectra of 2 and 3 show no dissociation, either at room or
dohalogen X = SCN, it was found that crystallization of low temperature.
[Cu(SCN)(PPh3)] from pyridine yielded a complex shown
The interaction of CuNCS with PPh3 in acetonitrile, in
∧
to be a 1:1:2 CuSCN/PPh3/py adduct (2), the first of that the presence of chelating N N aromatic ligands, such as
stoichiometry so defined. It was found to crystallize in a phen and bpy, afforded derivatives 4 and 5 of the form
chiral space group and to be strongly luminescent, which CuNCS/PPh3/L (1:1:1). They are stable solids with sharp
prompted study of its photophysical properties, aug- melting points. The IR spectra show strong absorptions at
mented by the synthesis and study of a number of N N- 2082 and 2089 cm–1, respectively, which are again indicative
∧
bidentate ligand counterparts:
a new polymorph of of Cu–NCS systems. The absorptions in the region 550–
[Cu(NCS)(phen)(PPh3)] (4) and [Cu(NCS)(bpy)L] (L = 420 cm–1, as also found for all derivatives 1–7, are clearly
PPh3, PPh2py) (5, 6), all mononuclear. In contrast to 2, indicative of the presence of aromatic phosphanes and are
the use of the more-hindered 2-methylpyridine base (Mepy) attributable to Whiffen’s “y” and “t” modes of vibration.[22]
results in centrosymmetric, binuclear [(Ph3P)(Mepy)- In the 1H NMR spectra, all the resonances of chelating
Cu(SCN
NCS)Cu(Mepy)(PPh3)], (3). We report solid-state 31P phen (derivative 4) or bpy (derivative 5) beyond those of
PPh3 were detected. For 4 and 5, the VT 31P NMR spectra
show no evidence for dissociation.
CPMAS NMR and photoemission data of the above com-
pounds, together with analyses of their quadrupolar split-
ting parameters due to the Cu–P interactions and corre-
lation with the structural behaviour; the photoemission
transitions were assigned with the assistance of TDDFT/
CPCM calculations.
We also explored the use of a different ditopic chelating
phosphane, diphenylpyridylphosphane (PPh2py), which of-
fers the possibility of py-N instead of, or as well as, P coor-
dination within the one ligand. Its interaction with CuNCS
in acetone, in the presence of bpy, afforded mononuclear
derivative 6, CuNCS/PPh2py/bpy (1:1:1). Finally, when the
same reaction was performed in pyridine as solvent, deriva-
Results and Discussion
From the interaction of copper(I) thiocyanate and tri- tive 7, CuNCS/PPh2py/py (1:1:1), was obtained, with the
∧
phenylphosphane in a 1:1 metal to phosphane ratio, in pyr- possibility of a P N-bidentate PPh2py ligand with a py
idine at room temperature, we obtained derivative 1, molecule also bonded to the Cu centre. The IR ν(S–CϵN)
CuSCN:PPh3 (1:1), which is a colourless and air- and absorptions, which fall at 2087 and 2086 cm–1 for 6 and 7,
moisture-stable compound that shows a sharp melting respectively, indicate that the NCS group is N-bonded to
1
point; it is soluble in acetonitrile and chlorinated solvents. the Cu atom. In the H NMR spectra of 6 and 7, broad
The most significant information from the infrared spectra multiplets were observed owing to PPh2py and to py (7).
in compounds such as 1 is related to the frequency of the The VT 31P NMR spectra of 6 seem to indicate a dissoci-
absorption band at ca. 2050–2100 cm–1, which is due to the ative equilibrium involving a PPh2py ligand, and three reso-
stretching vibration of (SCϵN); this band was reported to nances at 2.07, –0.78 and –3.65 ppm were detected; the lat-
be sensitive to the bonding type of the NCS group in metal ter presumably arose from a PPh2py ligand not bound
complexes.[20,21] In the spectrum of 1, this band is high- through the phosphorus atom. However we cannot, at pres-
frequency shifted, at 2094 cm–1, which is suggestive of a ent, discriminate between a fully dissociated and an N-coor-
bridging Cu–NCS–Cu framework, perhaps in a dimer or a dinated PPh2py ligand.
more complex polymeric system.
When the same reaction was carried out by warming at
ca. 60 °C, the triboluminescent derivative 2 was afforded
X-ray Diffraction Studies
with a 1:2:1 Cu:py:PPh3 ratio; that is, it contains two py
The results of the single-crystal X-ray studies are consis-
molecules as ligands. A similar reaction carried out in 2- tent in terms of stoichiometry and connectivity with the
Eur. J. Inorg. Chem. 2008, 1974–1984
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1975

C. Pettinari et al.
FULL PAPER
formulations of complexes 2 and 4–6 as [Cu(NCS)(py)2- comprises the asymmetric unit of the structure in each case;
∧
(PPh3)] (2) and [Cu(NCS)(N N-chelate)(R3P)] (4–6). One the pyridine adduct crystallizes in a chiral space group so
molecule (Figure 1), devoid of crystallographic symmetry, that each crystal is enantiomerically pure, although the
Figure 1. Projections of single molecules of (a) (i) [Cu(NCS)(py)2(PPh3)] (2); (ii) [Cu(NCS)(phen)(PPh3)] (4); (iii) [(NCS)(bpy)(PPh3)] (5);
(iv) [Cu(NCS)(bpy)(PPh2py)] (6). (b) [(Ph3P)(Mepy)Cu(SCN)Cu(Mepy)(PPh3)] (3).
NCS
1976
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1974–1984

∧
New [Cu(NCS){(L-N)2 or (LЈ-N N)}(PPh3)] Complexes
molecule has a potential mirror plane. The metal centre in
Steric control of the coordination number through the
each molecule is four-coordinate, and the thiocyanate use of hindered unidentate nitrogen (in particular, pyridine)
groups are N-coordinated with the coordination environ- base donors in coinage metal(I) [in particular, copper(I)]
∧
ments XMPN2, N N. The pyridine adduct is the first com- complexes has long been exploited, as, for example, in the
plex formulated as [CuX(unidentate-N-base)2(R3P)] to be crystallisation of copper(I) perchlorate from (the conve-
isolated and structurally defined; the new polymorph of the niently liquid) pyridine, 2-methylpyridine and 2,6-dimeth-
Cu/phen/NCS adduct augments the arrays of the form ylpyridine, whereby ionic mononuclear adducts of the form
[CuX(N,NЈ-bidentate ligand)(R3P)] previously described for [CuLn](ClO4), n = 4, 3, 2, respectively, were obtained.[23] In
bpy/X = Cl, Br, I as above, also augmented by the addition the present situation, the use of Mepy in place of py results
of the thiocyanate analogue of the bpy arrays with PPh3 in the formation of a complex of diminished stoichiometry
and Ph2pyP (5, 6). In the report of the bpy adduct, for (1:1:1), as might have been anticipated. However, there is
X = Cl,[6] two independent molecules were found in that no associated diminution in the coordination number (CN)
structure, and they were dependent on the conformation of of the copper(I) metal centre, and a coordination number
the PPh3 disposition vis-a-vis that of the (bpy)CuX array; of four is maintained by substitution of the less-sterically
one conformation (a) was only found for X = Br, I and two demanding S-terminal of the ambidentate thiocyanate
conformations (a,b) were found in the anhydrous chloride. group so that the latter presents as terminally bridging
The latter (b), which is a “rotamer” of (a), was also found SCN, within the context of the familiar binuclear eight-
in the hydrated form of the chloride, which is suggestive of membered Cu(SCN
NCS)Cu cyclic array. Thus, [(Ph3P)(Mepy)-
NCS)Cu(Mepy)(PPh3)] (3) is of the form that is similar
Cu(SCN
an inversion in stability in the two forms depending on the
bulk of the halide. Given that the donor of the pseudoha-
lide NCS group in all of the present complexes is the
smaller nitrogen atom, it is interesting to note the confor-
mation belonging to type (b), as might be expected. Finally,
we note that, in the array of 6, the use of Ph2pyP in place
of PPh3, which has an alternative N donor that may act as
a unidentate or bridging donor or form a chelate with the
to that of the pyridine/halide analogues.[2] Introduction of
the sulfur atom instead of the second pyridine or chelate
N-donor has relatively little impact on the remaining geo-
metries about the copper atom, and they are perhaps more
closely allied to those of py2 adduct 2, rather than those of
∧
the N N chelate complexes (Table 1, cf. Table 2).
In Table 1, it is of interest to note that, despite the change
phosphorus atom, does none of these things and simply in the aromatic N2-base donor array from a pair of uniden-
∧
forms mononuclear [Cu(NCS)(N N-bpy)(Ph2pyP)] (6), in tate ligands, (py)2, to a bidentate ligand (phen or bpy), ac-
which one molecule again comprises the asymmetric unit. companied by a substantial diminution in the in N(ar)–Cu–
There are no unusually close interactions with the pyridyl N(ar) bite angle, Cu–P and Cu–N(ar) are similar in both
nitrogen atom of the Ph2pyP ligand, which suggests an ag- types of complex. A notable change, however, is found in
gregate subtle interplay of intermolecular forces to be at the Cu–NCS affiliation, as Cu–N(NCS) diminishes appreci-
∧
work in determining that this complex is not isomorphous ably on passing from the (py)2 to the N N-chelate adducts,
with its PPh3 counterpart 6. Geometries of the present com- perhaps in consequence of a more spacious environment
plexes and those of the type (b) form of the chloride are for the anion, consequent on incorporation of the bidentate
presented comparatively in Table 1.
ligand and a straighter Cu–N–C angle. Although it is ex-
Table 1. Selected geometries of [CuX(aromatic base-N,NЈ)L] (L = PPh3, PPh2py).
∧
L/N( )NЈ/X
PPh3(py-N)2/NCS[a]
2
PPh3/phen/NCS[a,b]
4
PPh3/bpy/NCS
5
Distances [Å]
PPh2py/bpy/NCS
6
PPh3/bpy/Cl,Cl·H2O[c]
Compound
Cu–X
Cu–N(ar)
2.013(2)
2.091(2)
2.070(1)
2.1974(5)
1.638(2)
1.168(3)
1.960(5), 1.981(8)
2.106(4), 2.099(8)
2.072(3), 2.090(6)
2.200(1), 2.189(3)
1.638(6), 1.597(9)
1.162(7), 1.15(1)
1.946(2)
2.071(2)
2.063(2)
2.1748(9)
1.632(2)
1.165(3)
1.9736(13)
2.0800(12)
2.0874(12)
2.1813(4)
1.638(1)
2.307(6), 2.330(2)
2.10(1), 2.076(5)
2.14(2), 2.087(6)
2.219(6), 2.180(2)
–
Cu–P
S–C
C–N
1.163(2)
–
Angles [°]
X–Cu–N(ar)
99.58(8)
114.3(2), 110.9(3)
102.8(2), 104.1(3)
115.3(1), 115.8(3)
111.2(1), 117.6(2)
128.4(1), 122.6(2)
80.3(1), 80.5(3)
102.47(9)
115.56(9)
117.06(7)
124.25(6)
112.55(6)
79.61(9)
166.7(2)
178.4(3)
105.03(5)
100.25(5)
120.61(4)
121.53(4)
121.56(4)
79.28(5)
111.2(4), 104.5(2)
109.3(5), 102.9(5)
116.3(2), 117.1(1)
118.7(5), 123.2(1)
117.5(4), 122.8(2)
77.7(6), 79.2(2)
–
106.70(6)
115.34(6)
116.27(4)
116.29(4)
X–Cu–P
P–Cu–N(ar)
N(ar)–Cu–N(ar) 100.37(7)
Cu–N–C
N–C–S
157.4(2)
179.5(2)
170.8(3), 167.4(8)
179.3(4), 179(1)
176.58(12)
178.98(13)
–
[a] Cu lies 0.006(3) and 0.155(3) Å out of the two pyridine C5N planes in the (py)2 complex and 0.216(3) Å out of the C12N2 plane of
the present phen adduct. [b] The two entries are for the present polymorph, and for that of ref.[9] [c] The two entries are for molecule 2
of the unsolvated chloride[6] and the molecule of the hydrate,[7] both of those being of the same conformation as the present.
Eur. J. Inorg. Chem. 2008, 1974–1984
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1977

C. Pettinari et al.
FULL PAPER
Table 2. Selected geometries of [(Ph3P)(Mepy)Cu(SCN
NCS)Cu(Mepy)-
(PPh3)] (3).[a]
Distances [Å]
Cu–N
Cu–N1
S–C
2.009(2)
2.106(2)
1.655(2)
Cu–P
Cu–SЈ
C–N
2.2149(5)
2.4170(5)
1.159(2)
Angles [°]
N–Cu–N1
N–Cu–P
N–Cu–SЈ
Cu–SЈ–CЈ
N–C–S
100.75(7)
117.71(5)
101.21(5)
97.18(7)
179.0(2)
N1–Cu–P
N1–Cu–SЈ
P–Cu–SЈ
Cu–N–C
116.61(5)
103.34(5)
114.83(2)
154.0(2)
[a] Primed atoms are inversion related; N is the thiocyanate and
N1 the pyridine donor.
pected that the Cu–NCS array should be quasilinear, the
present situation may reflect greater rigidity in association
with the shorter, stronger bonds.
Solid-State NMR Spectroscopy
The 31P CPMAS spectra for all compounds under inves-
tigation are shown in Figure 2, and the NMR parameters
are summarized in Table 3. All the spectra are characterized
by a resonance that appears as a well-resolved quartet. The
spectra of 3, 6 and 7 are characterized by broad signals at
–12.4, 0.8 and –6.8 ppm, respectively. For compounds 6 and
7, this is probably due to different quadrupole relaxation
effects, as previously found by some of us for other three-
coordinate copper halide complexes containing tricyclohex-
ylphosphane.[24] In the case of 3, it also confirms the di-
meric nature of the complex. Conversely, the spectra of
samples 1, 2, 4 and 5, where resonances fall at –9.8, –7.2,
–2.8 and –3.8 ppm respectively, are characterized by one
quartet with very sharp peaks.
Figure 2. 31P CPMAS NMR spectra of [Cu(NCS)(PPh3)]2 (1),
[Cu(NCS)(py)2(PPh3)] (2), [Cu(NCS)(Mepy)(PPh3)]2 (3) [Cu(NCS)-
(phen)(PPh3)] (4), [Cu(NCS)(bpy)(PPh3)] (5), [Cu(NCS)(bpy)-
(PPh2py)] (6) and [Cu(NCS)(py)(PPh2py)] (7), recorded at
109.6 MHz with a spinning rate of 7 kHz.
actions between Cu and P when the quadrupolar coupling
There are two main reasons for the presence of the typi- is comparable to the Zeeman splitting energy. This produces
cal splitting pattern: the first is the presence of the 63Cu and different splittings between adjacent peaks in each quartet
1
65Cu isotopes, which are both quadrupolar and NMR with respect to J[31P,63Cu].
active (63Cu : I = 3/2, natural abundance 69.09% and
The quartets are also somewhat distorted according to
65Cu : I = 3/2, natural abundance 30.91%), that gives rise to Scheme 1, because the axis of quantization for the quadru-
two almost overlapped quartets mainly visible in the splitting polar copper isotopes is not exactly coincident with the di-
of the outer resonances. This is particularly evident in the rection of the applied magnetic field, B0. Spectral analysis
spectra of compounds 1, 2, 3, 4 and 5 reported in Figure 2. allows us to extract structural information from these com-
The second reason for the presence of such a splitting bined effects of dipolar, scalar and quadrupolar interac-
pattern is the inefficient averaging by the magic angle spin- tions,[25] such as, for example, bond lengths and angles,
ning of the dipolar and indirect coupling anisotropy inter- 63Cu quadrupole coupling constants and location of the
Table 3. 31P CPMAS NMR spectroscopic data for 1–7.
Compound
δ
∆ν1
[Hz]
∆ν2
[Hz]
∆ν3
[Hz]
Ͻ∆νϾ
[Hz]
d
[Hz]
dνCu/109
[MHz]
[ppm]
[Cu(NCS)(PPh3)]2 (1)
–9.8
–7.2
–12.4
–2.8
–3.8
0.8
1361
1537
1489
1523
1440
1550
1409
1489
1568
1599
1712
1520
1605
1569
1526
1581
1556
1786
1519
1575
1562
1459
1562
1548
1674
1493
1577
1513
–41.25
–11.00
–16.75
–65.75
–19.76
–6.25
–2.95
–0.79
–1.20
–4.71
–1.41
–0.45
–2.74
[Cu(NCS)(py)2(PPh3)] (2)
[Cu(NCS)(Mepy)(PPh3)]2 (3)
[Cu(NCS)(phen)(PPh3)] (4)
[Cu(NCS)(bpy)(PPh3)] (5)
[Cu(NCS)(bpy)(PPh2py)] (6)
[Cu(NCS)(py)(PPh2py)] (7)
–6.8
–38.25
1978
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Eur. J. Inorg. Chem. 2008, 1974–1984

∧
New [Cu(NCS){(L-N)2 or (LЈ-N N)}(PPh3)] Complexes
electric field gradients (EFG) at the copper atom with re- of the Cu–N bonds and that the EFG z axis is directed
spect to the molecular frame. Many examples of copper– along the direction of higher electron density. We thus fix
phosphane complexes have been discussed in the litera- the azimuthal (αD) and polar (βD) angles of the 31P,63Cu
ture,[26] and the analysis of such spectra has been described dipolar coupling constant (D) in the principal axis system
in detail.[27,28]
of the electric field gradient at the copper nucleus (EFG
principal axis system, PAS) (see Scheme 2) both equal to
zero.
Scheme 1.
For the interpretation of the present spectra a detailed
theory with parameter definitions is available in the Sup-
porting Information.[26–31]
Accurate analysis of the quadrupole parameters is pre-
sented only for [Cu(NCS)(py)2(PPh3)] (2), [Cu(NCS)-
(Mepy)(PPh3)]2 (3), [Cu(NCS)(phen)(PPh3)] (4), [Cu(NCS)-
Scheme 2.
For evaluating the quadrupolar coupling constant (e2qQ/
(bpy)(PPh3)] (5) and [Cu(NCS)(bpy)(PPh2py)] (6), for h), D and the anisotropy of the J tensor (∆J) are still re-
which X-ray structures are recorded. Indeed, when the P– quired; the former was obtained from the X-ray Cu–P dis-
Cu bond lengths are known from diffraction data, it is pos- tance. Indeed D = 12900/r3 Hz and, considering r =
sible to establish the existence of anisotropic ∆J effects, 2.197 Å, we obtain D = 1216 Hz. The anisotropy of the
which are otherwise difficult to distinguish from dipolar ef- tensor J[31P,63Cu], ∆J, according to the literature,[26j–26m]
fects.
was fixed in reasonable approximation in the range 0.5–
The 31P CPMAS NMR spectrum of [Cu(NCS)(py)2- 1.0 KHz.[31] Thus, following the equation d = –(3e2qQ/
(PPh3)] (2) (Figure 2) consists of a single resonance split 20hνCu)(D – ∆J/3)(3cos2βD – 1 + ηsin2βDcos2αD), we esti-
into a multiplet centred at δ = –7.2 ppm. The values of ∆ν1, mate a quadrupolar coupling constant value in the range
∆ν2 and ∆ν3 (defined as ∆ν1 = J – 2d, ∆ν2 = J and ∆ν3 = J + 2.5–3.0 MHz for [Cu(NCS)(py)2(PPh3)] (2). This value of
2d, see Scheme 1) are measured as 1537, 1568 and 1581 Hz, the quadrupolar coupling constant is relatively small com-
respectively. The values of Ͻ∆νϾ = 1/3(∆ν1 + ∆ν2 + ∆ν3) pared to other copper–phosphane complexes having tetra-
and ∆ν2 were used in approximating the J coupling constant hedral coordination at the copper centre and indicates a
|1J[31P,63Cu]| and are reported in Table 2.
relatively high symmetry for the copper coordination
Because in our case the centres of gravity of the quartets sphere. By following the same procedure, it was possible to
do not follow the relation (∆ν1 – ∆ν2) = (∆ν2 – ∆ν3), the obtain quadrupole coupling constant values of 3.9–4.7,
first-order perturbation theory results are inadequate to de- 15.0–17.8, 4.3–5.1 and 1.4–1.6 MHz for compounds 3, 4, 5
scribe the observed 31P splitting. Second-order effects were and 6, respectively.
considered here for interpreting the 31P NMR spectra, and
The large variation in the quadrupolar coupling con-
so d = (∆ν1 – ∆ν3)/4 defines the quadrupole-induced distor- stants observed for the monomers Cu(NCS)(L)(PPh3) with
tion. L = py (2), phen (4) and bpy (5) can be associated with
For the location of the copper EFG axes in the molecular the difference in the X-ray structure geometries (see above).
frame we followed the qualitative method described by Indeed, the reduced constraint of the pyridine ligands [Npy–
Vega,[30] which connects the relative electron populations Cu–Npy angle of 100.37(7)°] with respect to the phen and
and direction of EFG tensors in s–p hybrids of 14N com- bpy ligands results in a copper coordination sphere of 2
pounds when the molecules have a symmetry plane. The closer to tetrahedral geometry. Thus, the more symmetric
EFG is assumed to depend on the difference in electron copper environment is associated with a lower value of the
density in the metal 4p orbital obtained by considering the quadrupolar coupling constant.
first coordination sphere as defined by the X-ray diffraction
Conversely, the higher constraint of the phen and bpy
study. A similar approach was used by Olivieri[26j] to pro- ligands requiring smaller Nar–Cu–Nar angles [ca. 80.4° for
vide a qualitative picture of the 63Cu EFG in different phen and 79.61(9)° for bpy] results in a more unsymmetri-
PnCuXm complexes.
cal tetrahedral geometry around the metal centre, which
Throughout this paper we will thus assume that the elec- leads to shorter Cu–NCS distances and higher quadrupolar
tron populations of the Cu–P bonds are higher than those coupling constants. The higher steric hindrance associated
Eur. J. Inorg. Chem. 2008, 1974–1984
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1979

C. Pettinari et al.
FULL PAPER
with the phenanthroline ligand induces in 4 an increase in
The UV/Vis spectra of the d10 configuration of 2 shows
both the Cu–P and Cu–NCS distances and a larger differ- broad absorption bands up to about 300–350 nm. This is
ence in the Cu–Nar bond lengths [2.106(4) Å and 2.072(3) Å not unexpected, as copper(I) prevents the stabilization of
for 4 and 2.063(2) Å and 2.071(2) Å for 5]. Thus, the more its excited states through ligand field. As a consequence,
distorted tetrahedral environment in 4 leads to a higher the charge transfer and intraligand transitions dominate its
value of the quadrupolar coupling constant. In the case of photophysics, and the emissions from CuI complexes are
compound 6, the very low value of the induced distortion usually weak and with short lifetimes. Significant room-
term d and of the calculated quadrupolar coupling constant temperature phosphorescence is generally observed in mul-
are justified by the relative high symmetry around the cop- tinuclear or cluster complexes of copper and rarely in mo-
per atom. The dimeric structure and the different nature of nonuclear species.[33] DFT and TDDFT calculations were
the ligand in compound 3 do not allow further comparison carried out on complexes 2 and 4 in order to ascertain the
with the monomeric systems.
type of UV/Vis transitions. Geometries were optimized in
The quadrupole-induced distortion parameters obtained the gas phase, and the nature of all stationary points was
for complexes 1 and 7 are in agreement with the d values confirmed by performing frequency calculations. Bond
previously reported in the literature.[26]
lengths and angles of the optimized geometries do not differ
substantially from the corresponding X-ray values of com-
pounds 2 and 4. Cu–NCS bond lengths are slightly overesti-
mated (about 0.01 Å), but this is a known typical feature of
DFT calculations, possibly consequent upon lack of li-
bration corrections in the X-ray work. Also, we optimized
the structures of 2 and 4 in dichloromethane as solvent by
means of the CPCM method. In the case of 2, a very slow
convergence was observed, which is probably due to the
minimal rotational barrier of pyridine and phenyl rings
around the Cu–N and P–C bonds, respectively. The struc-
tures in dichloromethane and in the gas phase only slightly
differ from each other, which results in little difference in
the calculated UV/Vis transitions when compared to the ex-
perimental broad spectra. The analysis of the shift of ex-
cited state energies passing from gas to solution is beyond
the aim of the present study. The calculated UV/Vis spec-
trum of 2 is in agreement with the experimental broad ab-
sorption observed in the range between 300 and 350 nm.
The assignments of the absorptions were made with the
help of TDDFT/CPCM calculations in dichloromethane as
solvent (16 singlet excited states were produced) by using
the geometry optimized in solvent of 2 in the singlet ground
Electrochemical and Photoluminescence Properties
The cyclic voltammetric (CV) response in CH2Cl2 at a
glassy-carbon (GC) electrode of [Cu(NCS)(py)2(PPh3)] (2)
shows a reversible oxidation at E1/2 = 0.454 V and a chemi-
cally irreversible reduction at about Ep = –1.08 V (Support-
ing Information, Figure S1). The oxidation process most
likely corresponds to the redox couple Cu(+1/+2), whereas
the ill-defined reduction is followed by the deposition of
metallic copper on the electrode surface, which in turn un-
dergoes anodic stripping at about –0.17 V. Copper deposi-
tion is observed also in CV experiments performed at
higher scan rates (up to 50 V/s), which indicates fast decom-
position of the corresponding radical anion. As the com-
pound is fluorescent (see below), and there is a significant
difference between the first oxidation and the first reduction
potentials (i.e. the reaction could be “energy sufficient”[32]),
we tried to get electrochemiluminescence (ECL) emission
by the annihilation method. No ECL emissions were de-
tected, very probably due to the chemical irreversibility of
the reduction.
Table 4. TDDFT/CPCM calculated energies Ecal [nm] and oscillator strengths (f) of the first 16 singlet excited states of the sol-
vent(CPCM)- and gas-phase-optimized geometries of [Cu(NCS)(py)2(PPh3)] (2) and [Cu(NCS)(phen)(PPh3)] (4).
[Cu(NCS)(py)2(PPh3)] (2)
CPCM (CH2Cl2) Gas phase
[Cu(NCS)(phen)(PPh3)] (4)
CPCM (CH2Cl2) Gas phase
Ecalcd.
f
Ecalcd.
f
Ecalcd.
f
Ecalcd.
f
345
336
330
326
313
311
307
306
295
294
293
291
290
289
288
287
0.0112
0.0338
0.024
339
333
324
322
317
308
303
298
297
293
290
289
286
285
285
282
0.0274
0.0080
0.0260
0.0110
0.0008
0.0013
0.0057
0.0003
0.0063
0.0015
0.1103
0.0076
0.0303
0.0209
0.0076
0.0283
421
415
399
388
365
354
348
340
337
324
311
307
307
303
297
293
0.0225
0.0127
0.0052
0.0004
0.0535
0.0002
0.01
0.0042
0.0031
0.0004
0.0041
0.0168
0.0251
0.002
427
416
406
390
367
352
351
338
335
323
313
308
302
298
298
293
0.0303
0.0021
0.0040
0.0005
0.0641
0.0019
0.0093
0.0022
0.0050
0.0000
0.0351
0.0026
0.0045
0.0062
0.0388
0.0278
0.002
0.0026
0.0475
0.0034
0.0514
0.0086
0.0045
0.0042
0.0222
0.0148
0.0159
0.0182
0.0214
0.0467
0.0326
1980
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Eur. J. Inorg. Chem. 2008, 1974–1984

∧
New [Cu(NCS){(L-N)2 or (LЈ-N N)}(PPh3)] Complexes
state (see Table 4). Although TDDFT does not provide the
electronic structures of the excited states, their electronic
distribution and their localization may be visualized by
using the electron density difference maps (EDDMs).[34]
The EDDMs of the most intense transitions of 2 were cal-
culated and employed for the correct assignments of the
transition types. The GAUSSSUM program[35] was used for
EDDMs and for the representation of the absorption spec-
tra. This approach has precedent in the literature for de-
termining the excited-state structures and electron distribu-
tions associated with metal complexes containing diimine
and π-acceptor ligands.[36] The four most intense absorp-
tions of 2 (calculated at 336, 330, 311 and 306 nm) are of
the MLLCT type. The corresponding EDDMs (Figure 3)
show two transitions at 336 and 330 nm involving charge
transfer from the metal (with the contribution of the SCN
ligand) to the two pyridine rings, and two transitions at 311
and 306 nm involving charge transfer from the metal (with
some contribution from the SCN ligand) to the tri-
phenylphosphane. Similar results were obtained for 4 (Fig-
ure 4). In both cases, as expected, the transitions occurring
at higher energies are characterized by charge transfer
towards the triphenylphosphane ligand. Hence, it seems
reasonable that the MLLCT is the photoemitting state for
both complexes.
Figure 4. EDDMs of the four most intense transitions of
[Cu(NCS)(phen)(PPh3)] (4) calculated at 421, 415 (top) and 365,
297 nm (bottom). Red indicates a decrease in charge density,
whereas blue indicates an increase in charge density.
Table 5. Photoemission data of compounds 2 and 4.
Compound
Emission [nm]
Lifetime [ns]
[Cu(NCS)(py)2(PPh3)] (2)
[Cu(NCS)(phen)(PPh3)] (4)
426
490
5.8
15.3
Conclusions
This work has shown the accessibility of mixed N,P-
donor complexes such as [Cu(NCS)(Mepy)(PPh3)]2, [Cu-
(NCS)(phen)(PPh3)], [Cu(NCS)(bpy)(PPh3)], [Cu(NCS)-
(bpy)(PPh2py)] and [Cu(NCS)(py)(PPh2py)], as well as
[Cu(NCS)(py)2(PPh3)]. The formation and stoichiometry of
the adducts are strongly dependent on the reaction condi-
tions employed. The complexes were fully characterized by
spectroscopic and X-ray diffraction studies. Their 31P
CPMAS NMR spectra were analyzed to obtain the values
and signs of the quadrupole-induced distortion parameter,
d, which characterizes the observed distortions in the 31P
quartets. The isotropic 31P,63,65Cu indirect spin–spin coup-
ling constants measured in this work were compared to the
values describing the Cu local geometries previously ob-
tained for the large family of copper–triphenylphosphane
complexes; the coupling constants for the cases under inves-
tigation are quite sensitive to the copper environments.
The results of TDDFT/CPCM excited-state calculations
Figure 3. EDDMs of the four most intense transitions of
[Cu(NCS)(py)2(PPh3)] (2) calculated at 336, 330 (top) and 311,
306 nm (bottom). Red indicates a decrease in charge density,
whereas blue indicates an increase in charge density.
The relevant photoluminescence data of the complexes
under investigation collected at room temperature in in dichloromethane as solvent were fitted to the experimen-
CH2Cl2 (Supporting Information, Figure S2) are summa- tal UV/Vis absorption spectra of compounds 2 and 4, and
rized in Table 5. The spectrum of each complex shows a the four most intense transitions at lower energies were as-
broad emission at 370–490 nm.
signed to the MLLCT types.
Eur. J. Inorg. Chem. 2008, 1974–1984
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1981

C. Pettinari et al.
FULL PAPER
phen (0.180 g, 1 mmol) was stirred at room temperature for 1 h,
during which time a pale-yellow precipitate formed that was filtered
off, washed with acetonitrile (5 mL) and identified as compound 4.
It is soluble in chloroform and only poorly soluble in acetonitrile.
Experimental Section
Material and methods: All reagents were purchased from Alfa
(Karlsruhe) and Aldrich (Milwaukee) and used as received. The
samples for microanalyses were dried in vacuo to a constant weight
(20 °C, ca. 0.1 Torr). Elemental analyses (C, H, N, S) were per-
formed in-house with a Fisons Instruments 1108 CHNS-O Elemen-
tal Analyzer. IR spectra were recorded from 4000 to 100 cm–1 with
Yield: 92%. M.p. 216–218 °C (dec.). IR (nujol): ν = 2082 (vs) ν(S–
˜
CϵN), 1619 (br. m) ν(C=C + C=N), 526 (vs), 505 (vs), 485 (vs),
448 (m), 427 (m), 420 (m), 420 (m) ν(PPh3) cm–1. 1H NMR
(300 MHz, CDCl3, 293 K): δ = 7.24–7.38 (m, 15 H, PC18H15), 7.66,
7.83, 8.32, 8.85 (2 m and 2 s, 8 H, CHPhen) ppm. 31P NMR
(121.4 MHz, CDCl3, 293 K): δ = 0.65 (br. s) ppm. 31P NMR
(121.4 MHz, CDCl3, 223 K): δ = 0.06 (br. s) ppm. C31H23CuN3PS
(564.12): calcd. C 66.00, H 4.11, N 7.45, S 5.68; found C 65.70, H
4.16, N 7.61, S 6.01.
a Perkin–Elmer System 2000 FTIR instrument. H and 31P NMR
1
solution spectra were recorded with a VXR-300 Varian spectrome-
ter operating at room temperature (300 MHz for 1H, 121.4 MHz
for 31P). Melting points are uncorrected and were recorded with an
SMP3 Stuart instrument and with a capillary apparatus.
[Cu(NCS)(bpy)(PPh3)] (5): Compound 5 was prepared following a
procedure similar to that reported for 4 by using CuNCS (0.121 g,
1 mmol), PPh3 (0.262 g, 1 mmol) and bpy (0.156 g, 1 mmol) in ace-
tonitrile. The product is soluble in chloroform and only poorly sol-
Syntheses of Derivatives 1–7
[Cu(NCS)(PPh3)]2 (1): A pyridine solution (5 mL) containing
CuNCS (0.121 g, 1.0 mmol) and PPh3 (0.262 g, 1.0 mmol) was
stirred at room temperature until a colourless precipitate formed,
which was immediately filtered and identified as compound 1. It is
soluble in chloroform and acetonitrile. Yield: 85%. M.p. 169–
uble in acetonitrile. Yield: 87%. M.p. 189–192 °C. IR (nujol): ν =
˜
2089 (vs) ν(S–CϵN), 1592 (br. m), 1566 (m), 1560 (m) ν(C=C +
C=N), 519 (vs), 500 (vs), 473 (vs), 431 (m), 409 (m) ν(PPh3) cm–1.
1H NMR (300 MHz, CDCl3, 293 K): δ = 7.25–7.35 (m, 17 H,
PC18H15 + CHbpy), 7.85 (pt, J = 8 Hz, 2 H, CHbpy), 8.11 (br., 2 H,
CHbpy), 8.54, (br., 2 H, CHbpy) ppm. 31P NMR (121.4 MHz,
CDCl3, 293 K): δ = 0.45 br. s) ppm. 31P NMR (121.4 MHz, CDCl3,
223 K): δ = –0.04 (br. s) ppm. C29H23CuN3PS (540.10): calcd. C
64.49, H 4.29, N 7.78, S 5.94; found C 64.50, H 4.26, N 7.77, S
6.02.
171 °C. IR (nujol): ν = 2094 (vs) ν(S–CϵN), 517 (vs), 503 (vs), 487
˜
(m), 442 (m), 432 (m), 425 (w) ν(PPh3) cm–1. H NMR (300 MHz,
1
CDCl3, 293 K): δ = 7.22, 7.34 (2 m, 15 H, PC18H15) ppm. 31P NMR
(121.4 MHz, CDCl3, 293 K): δ = –1.36 (s) ppm. C18H15CuNPS
(371.90): calcd. C 59.44, H 3.94, N 3.65, S 8.35; found C 59.37, H
4.06, N 3.52, S 7.96.
[Cu(NCS)(py)2(PPh3)] (2): Compound 1 (0.192 g, 0.5 mmol) was
dissolved in pyridine (5 mL) by gently warming (≈60 °C) until dis-
solution was complete. Slow cooling and evaporation to half the
volume of the initial solution afforded a crystalline precipitate,
which was identified as derivative 2. It can be prepared also in the
following manner: a pyridine solution (5 mL) containing CuNCS
(0.121 g, 1 mmol) and PPh3 (0.262 g, 1 mmol) was stirred by warm-
ing to about 70 °C for 3 h, after which slow cooling and evapora-
tion to half the volume of the initial solution afforded a crystalline
precipitate, which was identified as derivative 2. It is soluble in
chloroform and acetonitrile. Yield: 88%. M.p. At 114–120 °C, some
decomposition was observed, with reduction in volume of the bulk
mass of sample and it then melted in the range 172–174 °C. IR
[Cu(NCS)(bpy)(PPh2py)] (6): Compound 6 was prepared following
a procedure similar to that reported for 4 by using CuNCS (0.121 g,
1 mmol), PPh2py (0.263 g, 1 mmol) and bpy (0.156 g, 1 mmol) in
acetone. The product is soluble in chloroform and slightly soluble
in acetone and acetonitrile. Yield: 91%. M.p. 162–164 °C. IR (nu-
jol): ν = 2089 (vs) ν(S–CϵN), 1593 (s), 1567 (s), 1560 (sh.) ν(C=C
˜
+ C=N), 522 (vs), 503 (vs), 473 (w), 430 (m), 410 (m), 395 (w)
ν(PPh3) cm–1. 1H NMR (300 MHz, CDCl3, 293 K): δ = 7.18, 7.59,
7.87, 8.16, 8.63 [5 m, 12 H, P(C5H4N)(C6H5)2 and CHbpy], 7.30,
7.45 [2 m, 10 H, P(C5H4N)(C6H5)2] ppm. 31P NMR (121.4 MHz,
CDCl3, 293 K): δ = 0.97 (br.) ppm. 31P NMR (121.4 MHz, CDCl3,
223 K): δ = 0.76 (br.) ppm. C28H32CuN4PS (551.17): calcd. C
62.15, H 4.10, N 10.35, S 5.93; found C 61.82, H 4.03, N 10.35, S
6.17.
(nujol): ν = 2066 (vs) ν(S–CϵN), 1590 (m) ν(C=C + C=N), 520
˜
(vs), 509 (vs), 494 (vs), 475 (m), 437 (m), 430 (m), 420 (m) ν(PPh3)
cm–1. 1H NMR (300 MHz, CDCl3, 293 K): δ = 7.31 (m, 15 H,
PC18H15), 7.35, 7.68, 8.62 (3 m, 10 H, C5H5N) ppm. 31P NMR
(121.4 MHz, CDCl3, 293 K): δ = 0.0 (br. s) ppm. 31P NMR
(121.4 MHz, CDCl3, 223 K): δ = –2.9 (br. s) ppm. C28H25CuN3PS
(530.11): calcd. C 64.25, H 4.65, N 7.75, S 5.91; found C 63.88, H
4.84, N 7.72, S 6.13.
[Cu(NCS)(py)(PPh2py)] (7): A pyridine solution (5 mL) containing
CuNCS (0.121 g, 1 mmol) and PPh2py (0.263 g, 1 mmol) was
stirred by gently warming (≈60 °C) for 2 h. The clear solution was
reduced to half volume and acetone (30 mL) was added. A colour-
less precipitate slowly formed that was filtered off, washed with
acetone (5 mL) and identified as compound 7. It is soluble in chlo-
[Cu(NCS)(Mepy)(PPh3)]2 (3): Compound 3 was prepared by dis-
solving CuNCS (0.121 g, 1 mmol) and PPh3 (0.262 g, 1 mmol) in
2-methylpyridine (15 mL) and allowing to stand. It is soluble in
chloroform and acetonitrile. Yield: 83%. M.p. 211–213 °C. IR (nu-
roform. Yield: 78%. M.p. 152–153 °C. IR (nujol): ν = 2086 (s) ν(S–
˜
CϵN), 1594 (m), 1558 (m), 1540 (m) ν(C=C + C=N), 517 (s), 500
1
(vs), 452 (s), 427 (m), 417 (m) ν(PPh3) cm–1. H NMR (300 MHz,
CDCl3, 293 K): δ = 7.30, 7.55, 7.67, 8.64 (4 m, 14 H, PC17H14N)
ppm. 31P NMR (121.4 MHz, CDCl3, 293 K): δ = –0.63 (s) ppm.
31P NMR (121.4 MHz, CDCl3, 223 K): δ = –2.48 (br. s) ppm.
C23H19CuN3PS (464.00): calcd. C 59.54, H 4.13, N 9.06, S 6.91;
found C 59.18, H 4.22, N 9.15, S 7.23.
jol): ν = 2095 (vs) ν(S–CϵN), 1582 (w) ν(C=C + C=N), 523 (sh.),
˜
516 (vs), 503 (vs), 487 (m), 442 (m), 433 (m), 425 (m), 416 (m)
1
ν(PPh3) cm–1. H NMR (300 MHz, CDCl3, 293 K): δ = 2.55 (s, 3
H, CH3C5H4N), 7.10 (m, 1 H, CHMepy), 7.17 (dd, J = 8 Hz, 1 H,
CHMepy), 7.22–7.34 (m, 15 H, PC18H15), 7.58 (pt, J = 8 Hz, 1 H,
CHMepy), 8.50 (br., 1 H, CHMepy) ppm. 31P NMR (121.4 MHz,
CDCl3, 293 K): δ = –0.65 (s) ppm. 31P NMR (121.4 MHz, CDCl3,
223 K): δ = –2.08 (s) ppm. C25H22CuN2PS (477.04): calcd. C 62.95,
H 4.65, N 5.87, S 6.72; found C 62.68, H 4.72, N 5.70, S 6.25.
Structure Determinations: CCD area detector diffractometer data
were measured (ω-scans, monochromatic Mo-Kα radiation, λ =
0.71073 Å) yielding Ntotal reflections, and these merged to N unique
(Rint cited) after “empirical”/multiscan absorption correction (pro-
prietary software); No with F Ͼ 4σ(F) were considered “observed”
[Cu(NCS)(phen)(PPh3)] (4): An acetonitrile suspension (20 mL) and used in the full-matrix least-squares refinements by refining
containing CuNCS (0.121 g, 1 mmol), PPh3 (0.262 g, 1 mmol) and anisotropic displacement parameter forms for the non-hydrogen
1982
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1974–1984

∧
New [Cu(NCS){(L-N)2 or (LЈ-N N)}(PPh3)] Complexes
atoms. Hydrogen atom treatment followed a “riding” model. Neu-
tral atom complex scattering factors were employed within the Xtal
3.7 and SHELXL 97 programs.[37] Pertinent results are given below
and in the Tables and Figures, the latter showing non-hydrogen
atoms with 50% probability amplitude displacement envelopes and
hydrogen atoms having arbitrary radii of 0.1 Å. Individual varia-
tions in procedure are noted as “Variata”. CCDC-617187,
-617188, -642533, -653453, -642534 and -653454 contain the sup-
plementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
hexafluorophosphate (TBAPF6). The locally constructed instru-
mentation for ECL measurements was described elsewhere.[38]
Fluorescence lifetime measurements employed a Fluorolog-3 –
TCSPC Picosecond Life-time measurement system (Horiba Jobin
Yvon) in time-correlated single-photon counting (TCSPC) mode.
The excitation source was a 295-nm wavelength NanoLED pulsed
laser with a repetition rate of 1 MHz by employing a IBH TBX-04
picosecond photon detector under TCSPC conditions. The instru-
ment response function (prompt) was obtained at 295 nm by using
Ludox suspension. The emission decay data were analyzed by using
the software DAS6 provided with the instrument. The analysis used
the statistical method, with iterative least-squares reconvolution by
assuming an exponential decay function. The best-fit assessment
was based on the parameter χ2, which was close to 1.0 for all sam-
ples and the distribution of weighted residual along the zero line.
Crystal/Refinement Data
[Cu(NCS)(py)2(PPh3)] (2) ϵ C29H25CuN3PS, Mr = 542.1. Mono-
clinic, space group P21 (C22, No. 4), a = 9.4371(8) Å, b =
15.186(1) Å, c = 10.2446(9) Å, β = 116.948(2)°, V = 1309 Å3. Dcalcd.
1.376 gcm–3. µMo
=
1.00 cm–1; specimen:
Density functional calculations were carried out with the
GAUSSIAN 03 program.[39] The singlet ground-state geometries of
the complexes were optimized in the gas phase by the B3LYP[40]
functional. The basis sets employed were the Los Alamos double-
ζ (LanL2Dz) for Cu by using the relativistic core potential (ECP),
which replaces the inner core electrons, and the 6-31G* for all other
atoms. Time-dependent density functional theory[41] (TDDFT)
combined with the conductor-like polarizable continuum model
(CPCM)[42] method with dichloromethane as solvent was used to
calculate the excited-state energies by means of G03.
(Z
=
2)
=
0.45ϫ0.35ϫ0.30 mm; Tmin/max = 0.93. 2θmax = 65°; Ntotal = 26542,
N = 4700 (Rint = 0.015), No = 4414; R = 0.022; Rw = 0.027; S =
1.02. |∆ρmax| = 0.34 eÅ–3. T = ca. 153 K. Variata: “Friedel” data
were retained distinct, and xabs was refined to –0.015(9). (x,y,z,
Uiso H
) were also refined.
[(Ph3P(Mepy)Cu(NSCCNS)(Mepy)(PPh3)] (3)
Mr = 954.0. Triclinic, space group P1 (Ci , No. 2) a = 8.3766(3) Å,
ϵ
C50H44Cu2N4P2S2,
1
¯
b = 9.2419(3) Å, c = 15.8188(5) Å, α = 87.279(1)°, β = 78.615(1)°,
γ = 66.758(1)°, V = 1102 Å3. Dcalcd. (Z = 1) = 1.437 gcm–3. µMo
=
The 31P CPMAS NMR spectra were measured with a JEOL GSE
270 (6.34 T) spectrometer operating at 109.6 MHz for 31P. Cylindri-
cal 5 mm o.d. zirconium rotors with a sample volume of 120 µL
and a spin rate in the range 6.0–7.0 KHz were employed. In a typi-
cal experiment the CP contact time was 3.5 ms and the recycle time
10 s. Phosphorus chemical shifts are quoted relative to the signal
from 85% phosphoric acid. For all samples the magic angle was
carefully adjusted from 79Br MAS spectra of KBr by minimizing
the line-width of the spinning side-bands of the satellite transitions.
1.17 cm–1; specimen: 0.30ϫ0.15ϫ0.06 mm; Tmin/max = 0.87. 2θmax
= 60°; Ntotal = 9482, N = 6126 (Rint = 0.019), No = 5004; R1
=
0.032; wR2 = 0.093; S = 1.09. |∆ρmax| = 0.53 eÅ–3. T = ca. 170 K.
[Cu(NCS)(phen)(PPh3)] (4) ϵ C31H23CuN3PS, Mr = 564.1. Tri-
¯
clinic, space group P1, a = 10.403(2) Å, b = 10.920(2) Å, c =
12.913(2) Å, α = 72.710(2)°, β = 77.642(3)°, γ = 69.234(2)°, V =
1300 Å3. Dcalcd. (Z = 2) = 1.441 gcm–3. µMo = 1.01 cm–1; specimen:
0.22ϫ0.12ϫ0.10 mm; Tmin/max = 0.77. 2θmax = 58°; Ntotal = 15420,
N = 6430 (Rint = 0.042), No = 4553; R = 0.050; Rw = 0.054; S =
1.55. |∆ρmax| = 1.09 eÅ–3. T = ca. 153 K.
Supporting Information (see footnote on the first page of this arti-
cle): Detailed NMR theory with parameter definitions for the 31P
spectrum interpretation; TDDFT/CPCM calculated UV absorp-
tion spectra of 2 and 4; cyclic voltammogram of 2.
[Cu(NCS)(bpy)(PPh3)] (5) ϵ C29H23CuN3PS, Mr = 540.1. Triclinic,
¯
space group P1, a = 9.115(2) Å, b = 9.150(2) Å, c = 16.950(4) Å, α
= 91.56(2)°, β = 91.64(2)°, γ = 116.95(2)°, V = 1258 Å3. Dcalcd.
(Z
=
2)
=
1.425 gcm–3. µMo
=
1.04 cm–1; specimen:
0.14ϫ0.13ϫ0.05 mm; Tmin/max = 0.97. 2θmax = 64°; Ntotal = 20064,
N = 8150 (Rint = 0.052), No = 4592; R1 = 0.041; wR2 = 0.11; S =
0.91. |∆ρmax| = 0.47 eÅ–3. T = ca. 100 K.
Acknowledgments
This work was supported by the Italian MUR (PRIN2006: “Mate-
riali Ibridi Metallo-Organici Multifunzionali con Leganti Poliazot-
ati”) and by the University of Camerino, University of Torino, Uni-
versity of Western Australia and University of Canterbury.
[Cu(NCS)(bpy)(PPh2py)] (6) ϵ C28H22CuN4PS, Mr = 541.1. Mono-
clinic, space group P21/c, a = 15.9005(7) Å, b = 8.8266(4) Å, c =
18.2233(7) Å, β = 98.769(2)°, V = 2528 Å3. Dcalcd. (Z = 4) =
1.419 gcm–3. µMo = 1.42 cm–1; specimen: 0.60ϫ0.60ϫ0.42 mm;
Tmin/max = 0.86. 2θmax = 64°; Ntotal = 39363, N = 7976 (Rint
=
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Received: November 19, 2007
Published Online: March 10, 2008
1984
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1974–1984