Structural forms in complexes of 2,9-dimethyl-1,10-phenanthroline with simple salts of copper(I) and other univalent 'closed shell' species

Article abstract of DOI:10.1016/j.ica.2007.11.009

Syntheses, spectroscopic and structural characterizations of a series of Cu(I)-phenanthroline complexes are reported. A single crystal X-ray structure determination is recorded for CuNO₃:dmp:MeCN (1:1:1), 'dmp' = 2,9-dimethyl-1,10-phenanthroline, showing it to be isomorphous with its previously studied tetrafluoroborate, perchlorate and hexafluorophosphate, and silver(I) perchlorate counterparts, the metal atom lying in a trigonal planar [(N^∧N)Cu(NCMe)] coordination environment, the anion not being coordinated. Structure (re-) determinations are also reported for a number of salts of the [Cu(dmp)₂]⁺ cation: the perchlorate, isomorphous with numerous other salts, not only of copper(I), but also lithium(I)), also the unsolvated nitrate, and a solvated form of the chloride.

Full text of DOI:10.1016/j.ica.2007.11.009

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 2365–2374
www.elsevier.com/locate/ica
Structural forms in complexes of 2,9-dimethyl-1,10-phenanthroline
with simple salts of copper(I) and other univalent ‘closed shell’ species
Siti Mutrofin a, Eric J. Chan a, Peter C. Healy c, Alessandro Marinelli b, Jean Ngoune b,
Claudio Pettinari b,*, Riccardo Pettinari b, Neil Somers a, Brian W. Skelton a, Allan H. White a
a Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA 6009, Australia
b
`
Dipartimento di Scienze Chimiche, Universita degli Studi di Camerino, via S. Agostino 1, 62032 Camerino MC, Italy
c School of Science, Griffith University, Nathan, Queensland 4111, Australia
Received 17 September 2007; accepted 11 November 2007
Available online 13 November 2007
Abstract
Syntheses, spectroscopic and structural characterizations of a series of Cu(I)-phenanthroline complexes are reported. A single crystal
X-ray structure determination is recorded for CuNO3:dmp:MeCN (1:1:1), ‘dmp’ = 2,9-dimethyl-1,10-phenanthroline, showing it to be
isomorphous with its previously studied tetrafluoroborate, perchlorate and hexafluorophosphate, and silver(I) perchlorate counterparts,
the metal atom lying in a trigonal planar [(N^N)Cu(NCMe)] coordination environment, the anion not being coordinated. Structure (re-)
determinations are also reported for a number of salts of the [Cu(dmp)2]+ cation: the perchlorate, isomorphous with numerous other
salts, not only of copper(I), but also lithium(I)), also the unsolvated nitrate, and a solvated form of the chloride.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Copper(I) complexes; 2,9-Dimethyl-1,10-phenanthroline; X-ray crystal structure
1. Introduction
which may not only be a feature of interest in its own right,
but may also bring about considerable distortion from
ideal symmetry in the coordination environment of the
metal atom, impacting thus directly, and less so, on the
spectroscopic characteristics.
Copper(I) complexes based on polypyridyl ligands are of
interest because of their utility in solar energy conversion
[1] and in supramolecular devices [2]. Of particular interest
is the capability of Cu(I)–(Nn-donor ligand) systems to act
as probes for biological structures [3–5], as catalysts for
allylic olefin oxidation [6] or, as recently described, as
organic–inorganic chain-like hybrid complexes displaying
interesting three-dimensional supramolecular architecture
[7,8]. The spectroscopic behaviour of salts of copper(I)
complexes with N,N0-aromatic bidentate ligands has
attracted widespread interest [9], and is predicated on a
knowledge of their crystal structures in which a dominant
feature is the parallel packing of the planar ligands such
as 2,20-bipyridyl (‘bpy’) and 1,10-phenanthroline (‘phen’),
Extensions of this work have encompassed studies of the
behaviour of systems in which the properties of the ligand
are varied electronically and/or sterically, a ligand of par-
ticular interest in this respect being 2,9-dimethyl-1,10-phe-
nanthroline (‘dmp’) [10], effects attributable to the steric
characteristics of this ligand being particularly evident in
the recently defined complex [Na(dmp)3]I ꢀ MeOH, where
the deformation is such as to result in a new stereochemis-
try [11]. Oxidative instability evidenced by complexes of the
parent ligand can be moderated by the introduction of 2,9-
substituents that provide steric inhibition to the planariza-
tion which would occur in conjunction with oxidation to a
Cu(II) species [12–14]. In the present report, we describe
the synthesis of a number of Cu–dmp complexes and
the structural characterizations of further examples of
*
Corresponding author. Tel.: +39 0737 402234; fax: +39 0737 637345.
E-mail address: Claudio.pettinari@unicam.it (C. Pettinari).
0020-1693/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.11.009

2366
S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
complexes of that ligand, and their relationship to counter-
part systems with other anions and metal atoms.
2.1.5. Synthesis of CuCl:dmp (1:2), 5
Compound 5 has been synthesised by the reaction of
CuCl (1.0 mmol) with 2.0 mmol of dmp. 95% Yield. M.p.
297 °C (dec.). Anal. Calcd. for C28H26ClCuN4O, C,
63.03; H, 4.91; N, 10.50. Found: C, 63.00; H, 5.17; N,
2. Experimental
2.1. Synthesis
10.61%. IR (nujol, cmꢁ1): 3050w m(C–H), 1654w, 1644w
. . .
m(C–H), 1621m, 1611m, 1580s, 1560m, 1508m m(C C,
•
1
. . .
2.1.1. Synthesis of CuNO3:dmp:MeCN (1:1:1), 1
C
N), 550m, 450w, 437w, 320w. H NMR (CDCl ): d,
•
3
Dmp (2,9-dimethyl-1,10-phenanthroline) (1 mmol) was
added to a solution of [Cu(MeCN)4]NO3, in acetonitrile
and 1,5-cyclooctadiene, prepared following the literature
2.45 (s, 12H, CH3dmp), 7.8d, 8.0s, 8.5d (12H, CHdmp).
2.1.6. Synthesis of CuCl:dmp:PPh3 (1:1:1), 6
ꢁ
ꢁ
method for the ClO4 and PF6 salts [15], under argon.
After 2 h a precipitate which has been identified as 1 was
obtained. 56% Yield. Anal. Calcd. for C16H15CuN4O3, C,
51.26; H, 4.03; N, 14.95. Found: C, 51.76; H, 4.09; N,
14.53%. IR (nujol, cmꢁ1): 3040w m(C–H), 1619w, 1588m,
Compound 6 has been synthesised by the interaction of
[CuCl(PPh3)2] (0.240 g, 0.38 mmol) with dmp (0.10 g,
0.48 mmol) in diethyl ether solution (30 ml), at room tem-
perature. The solution was stirred overnight. A pale-yellow
precipitate was slowly formed, which was shown to be
compound 6. 89% Yield. M.p. 230–232 °C. Anal. Calcd.
for C32H27ClCuN2P, C, 67.48; H, 4.78; N, 4.92. Found:
C, 67.33; H, 5.00; N, 4.76%. IR (nujol, cmꢁ1): 3040w
. . .
. . .
1558w, 1500m m(C C, C N), 553m, 527m, 509m,
•
•
1
487m, 441m, 418w, 315w, 247w, 225m, 203w. H NMR
(CDCl3): d, 2.0 (s, 3H, CH3MeCN), 2.8 (s, 6H, CH3dmp),
7.6d, 7.8s, 8.2d (6H, CHdmp).
. . .
. . .
m(C–H), 1619w, 1588m, 1558w, 1500m m(C C, C N),
•
•
553m, 527m, 509m, 487m, 441m, 418w, 315w, 247w,
1
2.1.2. Synthesis of CuBF4:dmp (1:2), 2
225m, 203w. H NMR (CDCl3): d, 2.8 (s, 6H, CH3dmp),
Compound 2 has been synthesised in 66% yield by the
interaction of [Cu(PPh3)4]BF4 (0.5 mmol) with dmp
(1 mmol) in diethyl ether. The suspension was stirred for
12 h, then filtered and the precipitate washed with a diethyl
ether:ethanol 1:1 solution mixture. M.p. 306 °C (dec.). Anal.
Calcd. for C28H24BCuF4N4, C, 59.33; H, 4.27; N, 9.88.
Found: C, 59.24; H, 4.12; N, 9.80%. IR (nujol, cmꢁ1):
3073w m(C–H), 1651w, 1616w, 1558m, 1561w, 1505m
7.2t, 7.3t, 7.5d (15H, CHPh), 7.6d, 7.8s, 8.2d (6H, CHdmp).
KM (MeCN, 1 ꢂ 10ꢁ3 M) = 1.4 lS/cm.
2.1.7. Synthesis of CuBr:dmp:PPh3 (1:1:1) ꢀ H2O, 7 ꢀ H2O
Compound 7 has been synthesised following the same
procedure reported for
6
by using 0.5 mmol of
[CuBr(PPh3)2] and 1.0 mmol of dmp. 97% Yield. M.p.
263–264 °C. Anal. Calcd. for C32H29BrCuN2OP, C, 60.81;
H, 4.62; N, 4.43. Found: C, 60.53; H, 4.39; N, 4.51%. IR
(nujol, cmꢁ1): 3050w m(C–H), 1651br m(C–H), 1621,
m(C C, C N), 553m, 521m, 435w, 319w, 244w. 1H
. . .
. . .
•
•
NMR (CDCl3): d, 2.5 (s, 12H, CH3dmp), 7.8d, 8.0s, 8.5d
(12H, CHdmp). KM (MeCN, 1 ꢂ 10ꢁ3 M) = 122 lS/cm.
1588m, 1557m, 1538w, 1499s m(C C, C N), 553m,
. . .
. . .
•
•
527s, 509s, 488s, 442m, 418m, 402w, 316m, 214w. 1H
NMR (CDCl3): d, 1.9 (s, H2O), 2.8 (s, 6H, CH3dmp), 7.2t,
7.3t, 7.5d (15H, CHPh), 7.6m, 7.9br, 8.2br (6H, CHdmp).
KM (MeCN, 1 ꢂ 10ꢁ3 M) = 1.7 lS/cm.
2.1.3. Synthesis of CuNO3:dmp (1:2), 3
Compound 3 has been synthesised in 94% yield follow-
ing a procedure analogous to that reported for compound
2 by using 0.5 mmol of [CuNO3(PCy3)2] and 1.5 mmol of
dmp. M.p. 307 °C. Anal. Calcd. for C28H24CuN5O3, C,
62.04; H, 4.46; N, 12.92. Found: C, 61.69; H, 4.70; N,
12.71%. IR (nujol, cmꢁ1): 1651w, 1645w m(C–H), 1621m,
2.1.8. Synthesis of CuI:dmp:PPh3 (1:1:1) ꢀ H2O, 8 ꢀ H2O
Compound 8 has been synthesised following the same
procedure reported for 6 by using 0.5 mmol of [CuI(PPh3)2]
and 1.0 mmol of dmp. 98% Yield. M.p. 345 °C (dec.). Anal.
Calcd. for C32H29CuIN2OP, C, 56.60; H, 4.30; N, 4.13.
Found: C, 56.93; H, 4.12; N, 4.18%. IR (nujol, cmꢁ1):
3050w m(C–H), 1652w m(C–H), 1621w, 1587m, 1558m,
. . .
. . .
1590s, 1559m, 1509m m(C C, C N), 580w, 550m,
•
•
1
525w, 448w, 439m, 429w, 416w, 323m, 270w, 228m. H
NMR (CDCl3): d, 2.4 (s, 12H, CH3dmp), 7.8d, 8.0s, 8.5d
(12H, CHdmp). KM (MeCN, 1 ꢂ 10ꢁ3 M) = 119 lS/cm.
. . .
. . .
1507m, 1498m m(C C, C N), 553m, 527s, 507s, 488s,
•
•
1
2.1.4. Synthesis of CuClO4:dmp (1:2), 4
442m, 432m, 421m, 402w, 316w, 248w, 213w. H NMR
(CDCl3): d, 1.9 (s, H2O), 2.9 (s, 6H, CH3dmp), 7.2t, 7.3t,
7.6d (15H, CHPh), 7.7d, 7.8s, 8.2d (6H, CHdmp). KM
(MeCN, 1 ꢂ 10ꢁ3 M) = 3.1 lS/cm.
Compound 4 has been synthesised in 95% yield follow-
ing the same procedure as for 2, by using 1.0 mmol of
[Cu(PPh3)4]ClO4 and 4.0 mmol dmp. M.p. 297 °C (dec.).
Anal. Calcd. for C28H24ClCuN4O4, C, 58.03; H, 4.17; N,
9.67. Found: C, 58.14; H, 4.34; N, 9.55%. IR (nujol,
2.1.9. Synthesis of CuSCN:dmp:PPh3 (1:1:1) ꢀ H2O,
9 ꢀ H2O
cmꢁ1): 3050w m(C–H), 1654w, 1644w m(C–H), 1621m,
. . .
161111m, 1589s, 1560m, 1540w, 1533w, 1508m m(C C,
Compound 9 has been synthesised following the same
procedure reported for 6 by using 0.5 mmol of [CuS-
CN(PPh3)2] and 1.0 mmol of dmp. 97% Yield. M.p. 240–
241 °C. Anal. Calcd. for C33H29CuN3OPS, C, 64.96; H,
•
1
. . .
C
N), 550m, 450w, 437w, 320w, 279w, 234w, 202w. H
•
NMR (CDCl3): d, 2.4 (s, 12H, CH3dmp), 7.8d, 8.0s, 8.5d
(12H, CHdmp). KM (MeCN, 1 ꢂ 10ꢁ3 M) = 128 lS/cm.

S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
2367
4.79; N, 6.89. Found: C, 65.36; H, 4.71; N, 7.03%. IR
(nujol, cmꢁ1): 3050w m(C–H), 1654w, 1647w m(C–H),
1617w, 1592m, 1560m, 1533w, 1522w, 1509m, 1498m
were used within the XTAL 3.7 or SHELXL 97 programs
[16]. Pertinent results are given below and in tables and
the figures; in the latter, displacement envelopes are shown
at 20 (298 K) or 50% (153 K) probability amplitude levels.
Individual variations in procedure are cited as ‘variata’..
. . .
. . .
m(C C, C N), 548m, 527s, 498s, 494s, 474w, 435s,
•
•
321w, 280w, 238w, 215w. 1H NMR (CDCl3): d, 2.1 (s,
H2O), 2.7 (s, 6H, CH3dmp), 7.1–7.2, 7.2–7.3 (15H, CHPh),
7.6d, 7.7s, 8.2d (6H, CHdmp). KM (MeCN,
1 ꢂ 10ꢁ3 M) = 0.9 lS/cm.
2.3. Crystal/refinement data
2.3.1. CuNO3:dmp:MeCN (1:1:1), 1
C16H15CuN4O3, M = 374.9. Monoclinic, space group
2.1.10. Synthesis of CuNO3:dmp:PPh3 (1:1:1), 10
Compound 10 has been synthesised following the same
procedure reported for 6 by using [CuNO3(PPh3)2]
(1.0 mmol) and dmp (1.0 mmol). 75% Yield. M.p. 223–
225 °C. Anal. Calcd. for C32H27CuN3O3P, C, 64.48; H,
4.57; N, 7.05. Found: C, 64.12; H, 4.51; N, 7.11%. IR
(nujol, cmꢁ1): 3057w m(C–H), 1586m, 1558m, 1538w,
P21/c ðC52h; No:14Þ, a = 10.8080(4), b = 19.5740(8), c =
3
˚
˚
7.8400(3) A, b = 111.206(1)°, V = 1546 A . Dc (Z = 4) =
1.610 g cmꢁ3. lMo = 14.4 cmꢁ1; specimen: 0.69 ꢂ 0.15 ꢂ
0.08 mm; ‘T’min/max = 0.91. 2hmax = 75°; Nt = 30054,
N = 8081 (Rint = 0.040), Noꢁ=3 5608; R1 (F2) = 0.039;
˚
wR2 = 0.11; |Dqmax| = 0.63 e A
.
. . .
. . .
1506w m(C C, C N), 550m, 526s, 449s, 442br, 316w,
Variata. The present complex is isomorphous with a
number of other related complexes (Table 1) and was
refined adopting the cell and coordinate settings as those
of the previously studied isomorphous perchlorate salt [15].
•
•
1
225w. H NMR (CDCl3): d, 2.5 (s, 6H, CH3dmp), 7.2–7.8
(15H, CHPh), 7.8d, 8.0s, 8.5d (6H, CHdmp). KM (MeCN,
1 ꢂ 10ꢁ3 M) = 4.8 lS/cm.
2.1.11. Synthesis of CuClO4:dmp:PBn3 (1:1:2), 11
2.3.2. CuNO3:dmp (1:2), 3
C28H24CuN5O3, M = 542.0. Monoclinic, space group
Compound 11 has been synthesised following the same
procedure reported for 6 by using 0.7 mmol of [Cu(PBn3)2]-
ClO4 and 0.5 mmol of dmp. 86% Yield. M.p. 179–181 °C.
Anal. Calcd. for C56H54ClCuN2O4P2, C, 68.63; H, 5.55;
N, 2.86. Found: C, 68.43; H, 5.63; N, 2.62%. IR (nujol,
cmꢁ1): 3500br m(O–H), 3060w m(C–H), 1600w, 1585w,
C2/c ðC62h; No:15Þ, a = 17.648(4), b = 11.698(2), c =
3
˚
˚
12.466(3) A, b = 113.61(3)°, V = 2358 A . Dc (Z = 4) =
1.527 g cmꢁ3. lMo = 9.7 cmꢁ1; specimen: 0.26 ꢂ 0.18 ꢂ
0.08 mm; ‘T’min/max = 0.90. 2hmax = 75°; Nt = 23424,
N = 6202 (Rint = 0.046), No = 4614; R1 (F2) = 0.040;
wR2 = 0.11; |Dqmax| = 0.82.
1558w m(C C, C N), 587w, 552w, 484m, 384w. 1H
. . .
. . .
•
•
NMR (CD3CN): d, 2.6 (s, 6H, CH3dmp), 3.0s, 3.1s (s,
12H, CH2PBn3), 7.1–7.4 (m, 30H, Ph), 7.6d, 7.9d, 8.2s,
8.4s, 8.7s (6H, CHdmp).
Variata. The compound has been the subject of a previ-
ous study [17] and was refined adopting the same cell and
coordinate settings as those of its previously studied iso-
morphous silver(I) analogue [18].
2.1.12. Synthesis of CuNO3:dmp:PBn3 (1:1:2), 12
Compound 12 has been synthesised following the same
1
2
1
2
2.3.3. CuClO4:dmp (1:2). CH2Cl2, 4 ꢀ CH2Cl2
procedure reported for
6
by using 0.4 mmol of
C28.5H25Cl2N4O4, M = 622.0. Triclinic, space group
1
ꢀ
[Cu(PBn3)2]NO3 and 0.1 mmol of dmp. 81% Yield. M.p.
169–170. °C. Anal. Calcd. for C56H54CuN3O3P2, C, 71.36;
H, 5.77; N, 4.46. Found: C, 71.31; H, 5.82; N, 4.61%. IR
(nujol, cmꢁ1): 3059w m(C–H), 1590m, 1559w, 1508w
P1 ðCi ; No:2Þ,
a = 10.684(2),
b = 11.216(2),
c =
˚
13.076(2) A, a = 67.259(3)°, b = 73.547(3)°, c = 73.429
(3)°, V = 1358 A . Dc (Z = 2) = 1.521 g cmꢁ3. lMo = 10.4
3
˚
cmꢁ1; specimen: 0.30 ꢂ 0.15 ꢂ 0.12 mm; ‘T’min/max = 0.71.
m(C C, C N), 587m, 574w, 550m, 484s, 386m. 1H
2hmax = 58°;
Nt = 15832,
N = 6633
(Rint = 0.046),
. . .
. . .
•
•
ꢁ3
˚
NMR (CDCl3): d, 2.4 (s, 6H, CH3dmp), 3.0s (s, 12H,
CH2PBn3), 7.2–7.4 (m, 30H, CHBn), 7.8d, 8.0s, 8.5d (6H,
CHdmp).
No = 4289; R = 0.046; Rw = 0.052; |Dqmax| = 0.48 e A .
Variata. T was ca. 298 K. The compound has been the
subject of a previous single counter instrument study
(R = 0.07) [19], which, although having a similar cell vol-
3
˚
2.2. Structure determinations
ume (1356 A at 295 K) does not report the presence of
any solvent molecule, which, in the present case models
as CH2Cl2, disordered about an inversion centre, the C
atom being half-weighted. The compound is isomorphous
with a number of other related complexes, Table 2, and
was refined adopting the cell and coordinate settings of
the recently recorded isomorphous lithium analogue [20].
Full spheres of CCD area-detector diffractometer data
were measured (Bruker AXS instrument; monochromatic
Mo Ka radiation, k = 0.71073 A; T ca. 153 K) yielding
Nt(otal) reflections, these merging to N unique (Rint cited)
after ‘empirical’/multiscan ‘absorption correction’ (pro-
prietary software), No with F > 4r(F) being considered
‘observed’. In the full matrix refinements, anisotropic dis-
placement parameters forms were refined for the non-
˚
2.3.4. CuCl:dmp (1:2). 2 12 H2O ꢀ MeOH,
5 ꢀ 2 12 H2O ꢀ MeOH
hydrogen atoms, (x, y, z, Uiso H
)
being included following
C29H33ClCuN4O3.5, M = 592.6. Triclinic, space group
P1, a = 12.799(3), b = 13.598(3), c = 18.688(4) A, a =
ꢀ
˚
a riding model. Neutral atom complex scattering factors

2368
S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
Table 1
Systems of the form MX:dmp:MeCN (1:1:1) (all otherwise unsolvated)
a
c
a
d
e
M, X
Cu, PF6
Cu, BF4
Cu, ClO4
296
Cu, NO3
Ag, ClO4
153
(a) Crystal data
T (K)
296
150
153
Crystal system
Space group
triclinic
P1
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/c
ꢀb
˚
a (A)
11.305(4)
12.479(5)
7.669(4)
106.42(4)
913
11.848(16)
19.296(3)
7.5061(11)
108.29(2)
1629
11.9101(9)
19.987(1)
7.636(1)
108.159(1)
1727
10.8080(4)
19.5740(8)
7.8400(3)
111.206(1)
1546
12.140(4)
19.315(3)
7.340(1)
107.459(4)
1662
˚
b (A)
˚
c (A)
b (°)
3
˚
V (A )
˚
Distances (A)
M–N(CMe)
M–N(ar)
M–N(ar)
1.850(6)
2.023(6)
2.010(4)
1.856(2)
2.019(2)
2.034(2)
1.852(7)
2.015(6)
2.039(7)
1.859(1)
2.030(1)
2.025(1)
2.088(2)
2.243(1)
2.280(2)
Angles (°)
(MeC)N–M–N(ar)
(MeC)N–M–N0(ar)
N(ar)–M–N0(ar)
M–N–C(CH3)
a
138.0(2)
138.8(2)
83.1(2)
140.79(7)
135.88(7)
83.17(6)
174.1(2)
139.0(3)
137.7(3)
82.9(2)
138.15(6)
137.98(6)
83.30(5)
175.4(1)
147.66(6)
137.36(6)
74.35(5)
171.0(2)
174.3(7)
175.1(8)
Ref. [15]; a is 87.91(5)°, c 117.69(3)° in the PF6 salt.
The space group is mis-cited as P1 in Ref. [15].
Ref. [27].
This work.
Ref. [18].
b
c
d
e
Table 2
Crystal data for MX:dmp (1:2)(. nS)
3
˚
˚
˚
˚
X/(.nS) [Ref.]
Space group
T (K)
a (A)
b (A)
c (A)
a (°)
b (°)
c (°)
V (A )
(a) M = Cu
BF4= 12 Me2COa
ꢀ
triclinic, P1 (‘a’)
90
10.6290(2)
10.514(2)
10.684(2)
10.5250(3)
7.4343(2)
12.799(3)
13.607(6)
13.2144(4)
14.067(4)
17.648(4)
11.7315(2)
11.0188(2)
11.119(2)
11.216(2)
11.1161(3)
11.8200(3)
13.598(3)
10.728(4)
10.7139(3)
17.687(6)
11.698(2)
12.0990(2)
12.8262(2)
12.889(2)
13.076(2)
13.3764(3)
15.4847(4)
18.688(4)
18.064(9)
18.4938(5)
10.337(5)
12.466(3)
18.0211(2)
67.681(1)
67.27(2)
67.259(3)
69.721(1)
71.243(1)
70.011(3)
73.716(1)
74.00(2)
73.036(1)
73.17(2)
73.429(3)
72.455(1)
86.619(1)
64.332(3)
1305
1307
1358
1368
1276
2754
2629
2616
2571
2358
2558
b
BF4= 12 CH2Cl2
triclinic, P1 (‘a’)
150
298
90
ꢀ
c,d
ClO4= 12 CH2Cl2
triclinic, P1 (‘a’)
73.547(3)
72.974(1)
82.344(1)
80.498(3)
94.45(4)
92.449(1)
91.04(3)
113.61(3)
ꢀ
a
PF6= 12 CH2Cl2
triclinic, P1 (‘a’)
ꢀ
NO3/2H2Oa,e
triclinic, P1
90
ꢀ
Cl=2 12 H2O ꢀ MeOHd
triclinic, P1
153
295
90
295
153
90
ꢀ
f
ClO4
PF6
monoclinic, P21/n (‘b’)
monoclinic, P21/n (‘b’)
monoclinic, P21/c
monoclinic, C2/c (‘d’)
orthorhombic, P212121
a
Br/H2Oe
d,g
NO3
a
BF4
(b) M = Ag
BF4=CH2Cl2
h
ꢀ
ꢀ
triclinic, P1 (‘a’)
183
153
153
153
10.711(2)
10.6186(6)
10.4753(7)
17.613(2)
11.285(2)
11.3411(6)
13.3829(9)
11.976(2)
13.275(2)
13.3675(8)
19.324(1)
12.329(2)
65.36(3)
64.897(1)
73.27(3)
70.84(3)
69.895(1)
1356
1347
2708
2415
ClO4= 12 EtOHi
triclinic, P1 (‘a’)
72.808(1)
91.392(2)
111.806(3)
tfsi
monoclinic, P21/n (‘c’)
monoclinic, C2/c (‘d’)
i
NO3
(c) M = Li
I/MeOHj
monoclinic, P21/n (‘c’)
monoclinic, P21/n (‘c’)
monoclinic, P21/n (‘c’)
153
153
153
153
10.252(2)
10.170(1)
10.175(2)
10.218(1)
13.517(2)
13.483(2)
13.665(2)
11.274(1)
18.838(2)
19.460(2)
19.185(3)
13.315(1)
95.574(2)
94.637(2)
95.834(3)
73.842(1)
2598
2660
2654
1311
tfsj
ClO4/MeOHj
ClO4= 12 MeOHj
ꢀ
triclinic, P1 (‘a’)
65.617(1)
72.411(1)
a
Ref. [10].
Ref. [29].
Ref. [19].
This work.
Ref. [28].
Ref. [30].
Ref. [17].
Ref. [31].
b
c
d
e
f
g
h
i
Ref. [18].
Ref. [20].
j

S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
2369
3
70.011(3)°, b = 80.498(3)°, c = 64.332(3)°, V = 2754 A . Dc
(Z = 4) = 1.429 g cmꢁ3. lMo = 9.3 cmꢁ1; specimen: 0.25 ꢂ
0.18 ꢂ 0.08 mm; ‘T’min/max = 0.88. 2hmax = 50°; Nt =
14945, N = 6708 (Rint = 0.034), No = 4875; R = 0.067;
at ꢄ1370, 1040 and 830 cmꢁ1 characteristic of ionic nitrate
groups [21–23].
˚
The IR spectra of the perchlorate and tetrafluoroborate
derivatives 2, 4 and 11 show two absorptions characteristic
of the XY4 group: a strong band in the range 1100–
1060 cmꢁ1 (m3) and a sharp medium band at ca. 625 cmꢁ1
(m4) [24]. These absorptions are very similar to those found
for [Cu(PPh3)4]ClO4 [25] and different from those reported
in the strongly distorted trigonal planar [CuClO4(Pcy3)2]
ꢁ3
˚
Rw = 0.10; |Dqmax| = 0.85 e A
.
Variata. Weak and limited data would support mean-
ingful anisotropic displacement parameter refinement for
Cu, and Cl, only. Difference map residues were modelled
as shown, associated hydrogen atoms being assigned from
difference maps.
ꢁ
[22]. They are indicative of an ionic uncomplexed ClO4
group in accordance with the structure found for com-
plexes 2, 4 below, and with the behaviour shown by these
complexes in solution.
3. Results and discussion
The adduct CuNO3:dmp:MeCN 1 has been synthesised
by the reaction of [Cu(MeCN)4]NO3 with dmp (2,9-
dimethyl-1,10-phenanthroline) in 1,5-cyclo-octadiene/
acetonitrile.
The reaction between excess dmp and [Cu(PR3)n]X in
diethyl ether, methanol or ethanol yielded complexes 2–4
according to Eq. (1).
In the metal-halide stretching frequency region, the only
substance to exhibit a significant absorption is 5, which dis-
plays a peak at ca. 225 cmꢁ1; although this frequency is
similar to that reported for analogous bis(pyrazolyl)meth-
ane derivatives [26], the X-ray work shows the structure
to be ionic.
The conductivity measurements were carried out only
on the stable solutions. The complexes 6–9 are non-elec-
trolytes in acetone, thus ruling out ionic structures such
as [Cu(dmp)(PPh3)]+Xꢁ. A negligible ionic dissociation
is found for derivative 10. All the other derivatives are
electrolytes in acetone, acetonitrile and dichloromethane,
consistent with the ionic structures found in the solid
state.
½CuðPR3ÞnꢃX þ 2dmp ! CuX : dmpð1 : 2Þ þ nPR3
2 : n ¼ 4; R ¼ Ph; X ¼ BF4; 3 : n ¼ 2; R ¼ cy;
X ¼ NO3; 4 : n ¼ 4; R ¼ Ph; X ¼ BF4:
ð1Þ
ð2Þ
In all cases complete displacement of the phosphine ligand
was observed independently of the P-donor and counter-
ion nature. By contrast, the adduct CuCl:dmp (1:2) 5 has
been prepared by the reaction of one equivalent of CuCl
with at least two equivalents of dmp in methanol.
When [(PPh3)2CuX] was employed as a starting reagent
only one phosphine ligand was displaced from the copper
centre even if excess dmp was used, the derivatives 6–9
being obtained in accordance with Eq. (3).
1
In the H NMR spectra (see Section 2), the signals due
to the N,N0-donor ligands (and in some cases also to PR3
donors) show different patterns with respect to those found
for the free donors, confirming the existence of the com-
1
plexes in solution. For example, in the H NMR spectra
of 2–5 the CH resonances due to dmp appear as broad
singlets or doublets, downfield shifted with respect to those
found in the free donors. The chemical shifts depend on the
nature of the complexes, the larger d being found in the
case of the ionic derivatives, and the lower in the case of
the neutral species 6–9.
½CuðPPh3Þ2ꢃX þ dmp ! CuX : dmp : PPh3ð1 : 1 : 1Þ
þ PPh3
ð3Þ
6 : X ¼ Cl; 7 : X ¼ Br; 8 : X ¼ I; 9 : X ¼ SCN:
By contrast CuNO3:dmp:PPh3 (10) can be synthesised only
when equimolar quantities of the starting copper reagent
[(PPh3)2Cu]NO3 and of dmp are employed.
If the starting copper complex contains coordinated tri-
benzylphosphine PBn3, the 1:1:2 adducts 11 and 12 formed
according to Eq. (4), no displacement of the P-donor being
found.
The results of the single crystal X-ray study of the 1:1:1
adduct of CuNO3 with dmp and MeCN are consistent with
that formulation in terms of stoichiometry and connectiv-
ity, being of the form [(MeCN)Cu(N,N0-dmp)](NO3), one
formula unit, devoid of crystallographic symmetry, com-
prising the asymmetric unit of the structure. Interestingly,
the structure is isomorphous with its tetrafluoroborate
and perchlorate counterparts, Table 1, despite the different
anion profile, but not the hexafluorophosphate, despite the
quasi-‘spherical’ nature of the latter being more akin to
these, albeit somewhat larger in size. The packing of the
tetrafluoroborate array has already been commented on
in Ref. [27]; a projection down the short axis, c, in Fig. 1
shows the stacking of the planes normal to the projection
axis. It is of interest to note that the silver(I)/perchlorate
analogue [18] is also isomorphous; the angular environ-
ment about the metal atom in that adduct is much more
unsymmetrical than in the copper(I) analogues, perhaps
reflecting some tendency toward incipient two-coordination.
½CuðPBn3Þ2ꢃX þ dmp ! CuX : dmp : PBn3 ð1 : 1 : 2Þ ð4Þ
11 : X ¼ ClO4; 12 : X ¼ NO3:
The copper(I) nitrato derivatives 1 and 10 exhibit spectra in
the region 1400–1100 cmꢁ1, which differ considerably from
those of the starting [(PR3)2CuNO3] in which the two high-
est frequency bands, whicꢁh arise from removal of the
degeneracy of the m3 NO3 mode, are separated by ca.
170 cmꢁ1 [21–23]. In 1 and 10 m1 and m4 differ in frequency
by ꢄ70–90 cmꢁ1. This suggests, for these compounds in the
solid state, the presence of a monodentate nitrato group.
By contrast, derivatives 3 and 12 show three absorptions

2370
S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
Fig. 1. Unit cell contents of [(MeCN)Cu(dmp)](NO3), projected down c.
The stacking of parallel cations shields the metal atom
from anion approaches: in the silver(I) complex, the closest
interaction contact to the metal atom, from the glide-
The other determinations reported are studies or rede-
terminations of 1:2 CuX:dmp adducts, variously solvated
(or not) which augment the considerable array of reports
already extant, Table 2, the results consistent with that stoi-
chiometry here for X = NO3 (unsolvated) (cf. the previous
˚
related image is 3.199(2) A; here in the copper(I) (nitrate)
˚
complex, to C(25), it is 3.105(2) A.
Table 3
Metal atom environments and distortion parameters, [10,28], hn, for [M(dmp)2]+ systems (°)
˚
˚
M/X/S
T (K)
M–N (A)
N–M–N (bite) (°)
N–M–N (other) (°)
hx (°)
hy (°)
hz (°)
dM (A)
ꢀ
(a) ‘a’-Triclinic P1 form
Cu=BF4= 12 Me2COa
90
2.000(1)–2.112(2)
2.006(2)–2.139(2)
2.003(3)–2.143(2)
2.008(2)–2.116(2)
2.249(6)–2.411(5)
2.247(2)–2.413(2)
2.042(4)–2.118(3)
81.69(6), 81.77(6)
81.6(1), 81.5(1)
81.3(1), 81.4(1)
81.70(6), 81.78(6)
72.2(2), 72.7(2)
72.55(9), 72.91(1)
81.8(1), 82.4(1)
109.85(6)–137.44(6)
108.0(1)–137.9(1)
108.1(1)–137.1(1)
103.27(6)–134.26(6)
107.9(2)–143.4(2)
106.3(1)–143.83(8)
107.2(2)–138.2(1)
90.0
90.4
89.5
84.5
88.8
89.2
90.6
107.7
107.9
107.3
107.3
111.5
113.3
107.0
98.7
99.0
99.2
103.9
103.6
103.8
101.2
0.021, 0.442
0.008, 0.513
0.036, 0.512
0.090, 0.364
0.001, 0.589(5)
0.001(2), 0.512
0.045, 0.654
b
= 12 CH2Cl2
150
298
90
183
153
153
c
ClO4= 12 CH2Cl2
a
PF6= 12 CH2Cl2
d
Ag=BF4=CH2Cl2
ClO4= 12 EtOHe
Li=ClO4= 12 MeOHf
ꢀ
(b) ‘Other’ triclinic ðP1Þ forms
Cu/NO3/2H2Oa
90
2.024(2)–2.039(2)
2.021(7)–2.045(6)
2.027(6)–2.065(6)
81.10(6), 82.64(6)
82.4(2), 82.6(3)
81.6(2), 82.0(3)
118.62(6)–131.28(6)
115.9(3)–132.6(2)
119.4(2)–128.7(3)
91.9
87.6
87.5
96.1
90.9
91.5
95.0
103.0
96.0
0.033, 0.052
0.045, 0.075
0.045, 0.099
Cl=2 12 H2O ꢀ MeOHc
(mol. 1)
(mol. 2)
(c) ‘b’-Monoclinic P21/n form
Cu/ClO4/g
PF6/a
295
90
2.020(5)–2.077(6)
2.028(2)–2.070(2)
81.3(3), 81.7(2)
81.78(8), 81.95(8)
114.9(2)–130.8(2)
110.75(8)–132.11(8)
87.2
86.1
96.8
99.9
98.2
100.6
0.002, 0.234
0.095, 0.246
(d) ‘c’-Monoclinic P21/n form
Ag/tfs/e
153
153
153
153
2.248(1)–2.404(1)
2.030(3)–2.116(3)
2.059(4)–2.106(4)
2.061(5)–2.121(5)
72.45(4), 73.06(4)
81.9(1), 82.3(1)
81.4(1), 81.6(2)
81.3(2), 81.7(2)
107.28(4)–147.02(4)
107.9(1)–136.7(2)
107.9(2)–140.0(2)
106.3(2)–139.6(2)
92.2
89.3
91.8
90.9
112.1
105.3
105.5
107.7
105.1
101.2
103.2
102.5
0.160, 0.556
0.112, 0.705
0.178, 0.582
0.239, 0.582
Li/tfs/f
I/MeOHf
ClO4/MeOHf
(e) ‘d’-Monoclinic C2/c form
Cu/NO3/c
Ag/NO3/e
153
153
2.043(1), 2.061(1)
2.304(1), 2.337(1)
82.13(4)
73.27(5)
109.65(6)–134.61(4)
115.60(4)–140.57(5)
86.2
86.8
95.3
94.6
109.0
112.0
0.081
0.086
(f) Other monoclinic (P21/c) forms
Cu/Br/H2Oh
295
2.027(5)–2.053(5)
82.4(2), 82.9(2)
114.7(2)–135.2(2)
92.0
91.7
97.8
100.1
88.1
0.103, 0.132
0.007, 0.176
(g) Orthorhombic P212121 form
Cu/BF4/a
90
1.997(1)–2.045(1)
82.86(5), 83.05(5)
115.42(5)–130.48(5)
100.7
˚
dM A are the out-of-plane deviations of the metal atoms.
a
Ref. [10].
Ref. [29].
This work.
Ref. [31].
b
c
d
e
Ref. [18].
f
Ref. [20] (‘tfs’ = trifluoromethanesulfonate).
Ref. [30].
Ref. [28].
g
h

S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
2371
study of ref. [17]), X = ClO4 (cf. the previous report of Ref.
[19], wherein, obtained from ethanol/water solution, it was
reported as unsolvated, albeit with a similar cell volume to
the present), and X = Cl (the solvation modelled as meth-
anol/water). In the perchlorate, a single formula unit
devoid of crystallographic symmetry, comprises the
asymmetric unit of the structure, albeit with the dichloro-
methane solvent molecule lying disposed about a crystallo-
graphic inversion centre, with the carbon atom modelled as
disordered to either side. In the nitrate one half of the for-
mula unit comprises the asymmetric unit, the cation being
disposed with the copper atom lying on a crystallographic
2-axis and the anion disordered about an inversion centre.
The chloride is of a new structural type with two formula
units devoid of crystallographic symmetry comprising the
asymmetric unit. The geometries about the metal atoms
are as expected, within the quite wide ranges of values evi-
dent across the wide array of compounds previously stud-
ied, with substantial distortions evident [10,28], presumably
consequent on ‘lattice forces’.
quasi-‘closed shell’. In this respect it is interesting to com-
pare lithium and copper adducts within the same family,
which shows their metal environments to be generally very
similar, ceterus paribus, so that a lithium-silver comparison
in a family lacking a copper representative, may neverthe-
less, substitute usefully for copper–silver. Of the three
metal types, silver is the outlier, by virtue of its size, and
perhaps also electronic tendencies, displaying the most
extreme angular excursions in the MN4 arrays, as well as
in the distortion parameters hn. Unit cell projections of
the more common ‘a’–‘d’ forms are shown in Figs. 2–5.
Fig. 6 represents the relative orientations of the N1A–
M–N1B and N2A–M–N2B planes of the MN4 coordina-
tion sphere of [M(dmp)2]+ complexes. For molecules
adopting D2d symmetry, the four interligand angles are
equal to arcos(ꢁcos2(a/2) where a is the N–M–N chelate
angle. For the values of a = 82°, typical of those found
for copper and lithium complexes, these interligand angles,
undistorted, would be 124.7°, while for values of 72°
observed for silver complexes, these angles would be
131.9°. Angular distortions from D2d symmetry are conve-
niently described by the specification of three angles hx, hy,
and hz (Ref. [28]) which refer to the orientations of the
planes N1A–M–N1B and N2A–M–N2B with respect to
each other. Orthonormal vectors x, y, z are arbitrarily cho-
sen with origin M such that N1A–M–N1B lies in the xz
plane (Fig. 6). hx, hy, and hz represent rotations of N2A–
M–N2B about x, y and z, respectively, with respect to
N1A–M–N1B. hx is the angle between the bisector of
N2A–M–N2B and y, while hy is the angle between the
bisector to N2A–M–N2B and x. Both represent rocking
For salts of [M(dmp)2]+ with ‘simple’ symmetrical
anions, it is apparent (Table 2), that for a variety of metal
atoms whose adducts have been hitherto studied
(M = Cu(I), Ag(I), Li(I)), a limited number of crystalline
forms are found, some lattice types accommodating anions
of quite diverse symmetry, shape, and bulk, augmented/
compensated in a number of cases by solvent components,
similarly diverse, with concomitant variations in the distor-
tion parameters observed (Table 3); there may, of course,
be an additional variant arising out of the subtleties of
the differences in electron configuration, despite all being
Fig. 2. Unit cell contents of [Cu(dmp)2](NO3), projected down b (monoclinic, ‘d’ form).

2372
S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
Fig. 3. Unit cell contents of [Cu(dmp)2](ClO4). 1 CH2Cl2, projected down a (triclinic, ‘a’ form).
2
Fig. 4. Unit cell contents of [Cu(dmp)2]Cl. 2 12 H2O ꢀ MeOH, projected down a.

S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
2373
Fig. 5. Projections of representative unit cells of the ‘b’- and ‘c’-monoclinic forms down their b axes: (a) [Cu(dmp)2](ClO4), (b) [Li(dmp)2](tfs).
motions of the two planes with respect to each other. hz is
the (dihedral) angle between the normals to N1A–M–N1B
and N2A–M–N2B and represents the angle of ‘twist’
between the two planes or [10] the ‘flattening’ of the array;

2374
S. Mutrofin et al. / Inorganica Chimica Acta 361 (2008) 2365–2374
[7] S. Lopez, S.W. Keller, Cryst. Eng. 2 (1999) 101.
Y
[8] S. Wang, Y. Li, E. Wang, G. Luan, C. Hu, N. Hu, H. Jia, J. Solid
State Chem. 167 (2002) 402.
[9] (e.g.): A.C.S. Samia, J. Cody, C.J. Fahrni, C. Burda, J. Phys. Chem.
B. 108 (2004) 563.
X
[10] A. Yu Kovalevsky, M. Gembicky, I.V. Novozhilova, P. Coppens,
Inorg. Chem. 42 (2003) 8794.
N2A
[11] J.H.N. Buttery, Effendy, S. Mutrofin, N.C. Plackett, B.W. Skelton,
C.R. Whitaker, A.H. White, Z. Anorg. Allg. Chem. 632 (2006)
1851.
[12] Y. Lei, F.C. Anson, Inorg. Chem. 34 (1995) 1083.
[13] C.O. Dietrich-Buchecker, P.A. Marnot, J.P. Sauvage, Tetrahedron
Lett. 23 (1982) 5291.
N1A
N1B
Z
M
[14] M.A. Masood, R. Jagannathan, P.S. Zacharias, J. Chem. Soc.,
Dalton Trans. (1991) 2553.
[15] M. Munakata, M. Maekawa, S. Kitagawa, S. Matsuyama, H.
Masuda, Inorg. Chem. 28 (1989) 4300.
N2B
[16] (a) S.R. Hall, D.J. du Boulay, R. Olthof-Hazekamp (Eds.), The X-TAL
System – Version 3.7, University of Western Australia, 2001;
(b) G.M. Sheldrick, SHELXL 97: A Program for Crystal Structure
Refinement, University of Go¨ttingen, 1997.
[17] R. Hamalainen, M. Ahlgren, U. Turpeinen, T. Raikas, Cryst. Struct.
Commun. 8 (1979) 75.
Fig. 6. Schematic representation of the distortions around the copper
centre in ½MðIÞðdmpÞ2þꢃ complexes (see text).
[18] G.A. Bowmaker, Effendy, S. Marfuah, B.W. Skelton, A.H. White,
Inorg. Chim. Acta 358 (2005) 4371.
[19] A. Yu Kon, I.F. Burshtein, N.N. Proskina, B.T. Ibragimov, Koord.
Khim. 13 (1987) 260.
it should be noted that the values of hx, hy, and hz may be
acute or obtuse depending on the relative motions of the
ligands and on the specific definition of atom N1A.
[20] J.H.N. Buttery, Effendy, S. Mutrofin, N.C. Plackett, B.W. Skelton,
N. Somers, C.R. Whitaker, A.H. White, Z. Anorg. Allg. Chem. 632
(2006) 1839.
Appendix A. Supplementary material
[21] F.H. Jardine, A.G. Vohra, F.J. Young, J. Inorg. Nucl. Chem. 33
(1971) 2941.
[22] R. Restivo, A. Costin, G. Ferguson, A.J. Carty, Can. J. Chem. 53
(1975) 1949.
[23] A.B.P. Lever, E. Mantovani, B.S. Ramaswamy, Can. J. Chem. 49
(1971) 1957.
[24] M.R. Rosenthal, J. Chem. Educ. 50 (1973) 331.
[25] C. Pettinari, F. Marchetti, R. Polimante, A. Cingolani, G. Portalone,
M. Colapietro, Inorg. Chim. Acta 249 (1996) 215.
[26] C. Pettinari, G. Gioia Lobbia, G. Sclavi, D. Leonesi, M. Colapietro,
G. Portalone, Polyhedron 14 (1995) 1709.
CCDC 618704, 618705, 618706, and 618707 contains the
supplementary 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. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.ica.2007.11.009.
References
[27] A.J. Blake, P. Hubberste, W.-S. Li, D.J. Quinlan, C.E. Russell, C.L.
Sampson, J. Chem. Soc., Dalton Trans. (1999) 4261.
[28] (a) J.F. Dobson, B.E. Green, P.C. Healy, C.H.L. Kennard, C.
Pakawatchai, A.H. White, Aust. J. Chem. 37 (1984) 649;
see also: (b) R. Hamalainen, U. Turpeinen, M. Ahlgren, T. Raikas,
Finn. Chem. Lett. (1978) 199.
[1] N. Alonso-Vante, J.-F. Nierengarten, J.-P. Sauvage, J. Chem. Soc.,
Dalton Trans. (1994) 1649.
[2] P. Baxter, J.M. Lehn, A. DeCian, J. Fischer, Angew. Chem. Int. Ed.
Eng. 32 (1993) 89.
[3] Z. Yang, J. Yu, H. Chen, Electroanalysis 14 (2002) 747.
[4] G.W. Muth, C.M. Thompson, W.E. Hill, Nucleic Acids Res. 27
(1999) 1906.
[29] A.J. Blake, S.J. Hill, P. Hubberste, W.-S. Li, J. Chem. Soc., Dalton
Trans. (1998) 909.
[30] G. Dessy, V. Fares, Cryst. Struct. Commun. 8 (1979) 507.
[31] A.J. Pallenberg, T.M. Marschner, D.M. Barnhart, Polyhedron 16
(1997) 2711.
[5] S. Mahadevan, M. Palaniandavar, Inorg. Chem. 37 (1998) 693, 3927.
[6] G. Chelucci, A. Iuliano, D. Muroni, A. Saba, J. Mol. Catal. A: Chem.
191 (2003) 29.