Doubly N-confused porphyrin: A new complexing agent capable of stabilizing higher oxidation states

Article abstract of DOI:10.1021/ja992679g

A doubly N-confused porphyrin (N₂CP), 2-ethoxy-5,10,15,20- tetrapentafluorophenyl-3,7-diaza-21,22-dicarbaporphyrin, and its Ag(III) and Cu(III) complexes were synthesized for the first time, via an acid-catalyzed condensation of pentafluorobenzaldehyde and meso-pentafluorophenyl-2,3'- dipyrromethane. ¹H NMR and single-crystal X-ray diffraction analyses reveal the arrangement of the three hydrogens (two CH and one NH) in the core of N₂CP both in solution and in the solid state, respectively. The diamagnetic silver(III) complex has a square-planar tetracoordination and short Ag(III)-C bond distances of 1.987(8) and 2.011(8) A. Similarly, the diamagnetic Cu(III) complex shows a square-planar coordination with Cu(III)-C bond distances of 1.939(3) and 1.934(4) A. The trianionic nature of the N₂CP ligand and a possibility of stabilizing the higher oxidation state by confusion are discussed.

Full text of DOI:10.1021/ja992679g

J. Am. Chem. Soc. 2000, 122, 803-807
803
Doubly N-Confused Porphyrin: A New Complexing Agent Capable
of Stabilizing Higher Oxidation States
Hiroyuki Furuta,* Hiromitsu Maeda, and Atsuhiro Osuka*
Contribution from the Department of Chemistry, Graduate School of Science, Kyoto UniVersity,
Kyoto 606-8502, Japan
ReceiVed July 29, 1999. ReVised Manuscript ReceiVed NoVember 10, 1999
Abstract: A doubly N-confused porphyrin (N2CP), 2-ethoxy-5,10,15,20-tetrapentafluorophenyl-3,7-diaza-21,22-
dicarbaporphyrin, and its Ag(III) and Cu(III) complexes were synthesized for the first time, via an acid-
catalyzed condensation of pentafluorobenzaldehyde and meso-pentafluorophenyl-2,3′-dipyrromethane. 1H NMR
and single-crystal X-ray diffraction analyses reveal the arrangement of the three hydrogens (two CH and one
NH) in the core of N2CP both in solution and in the solid state, respectively. The diamagnetic silver(III)
complex has a square-planar tetracoordination and short Ag(III)-C bond distances of 1.987(8) and 2.011(8)
Å. Similarly, the diamagnetic Cu(III) complex shows a square-planar coordination with Cu(III)-C bond distances
of 1.939(3) and 1.934(4) Å. The trianionic nature of the N2CP ligand and a possibility of stabilizing the higher
oxidation state by “confusion” are discussed.
Introduction
be driven simply by deprotonation of the outward pointing NH
in the “confused” pyrrole, which serves to stabilize the polarized
carbon-metal bond. If such effects were observed for other
N-confused porphyrins, it could provide a potent strategy for
stabilizing higher oxidation states of metals,6 especially if more
than one confused pyrrole could be incorporated within any
given porphyrin-like macrocycle. This idea promoted us to
synthesize doubly N-confused porphyrins and to investigate their
metal coordination properties. In this paper, we report the
synthesis of 2-ethoxy-5,10,15,20-tetrapentafluorophenyl-3,7-
diaza-21,22-dicarbaporphyrin (N2CP, 7) and show that it is
capable of stabilizing complexes containing rather rare Ag(III)
and Cu(III) centers (i.e., 8 and 9). To the best of our knowledge,
these are the first examples of a porphyrin isomer containing
two confused pyrrole rings and its metal complexes.
Syntheses and metal coordination chemistry of porphyrin
analogues have been attracting considerable interest due to the
possibility of developing new porphyrin chemistry.1 Among
them, a porphyrin isomer, “N-confused porphyrin” (NCP, 1),2
originally synthesized by us and independently by Latos-
Graz˘yn´ski et al., is of interest because many “mutants” are
structurally possible, and its unique properties have been
revealed gradually.3-5 One of the features of NCP chemistry,
which differs from normal porphyrins, is its multivalent nature
as a metal ligand. NCP was found to complex either divalent
Ni(II) or trivalent silver(III) to give a square-planar complex
(2 or 3).3e,4a This characteristic chameleon-like nature seems to
(1) (a) Sessler, J. L.; Weghorn S. J. Expanded, Contracted, and Isomeric
Porphyrins; Elsevier: Oxford, 1997. (b) The Porphyrin Handbook; Kadish,
K. M., Smith, K. M., Guilard, R., Eds; Academic Press: San Diego, 1999;
Vol. 2.
(2) At present, several names for this isomer can be spotted in the
literature: carbaporphyrin, inverted porphyrin, N-confused porphyrin, mutant
porphyrin, 2-aza-21-carbaporphyrin, etc. We think the general nomenclature
such as 18-porphyrin (1.1.1.1.)-(CR,N,N,N) for 1 is appropriate to identify
the number and position of confused pyrrole among 14 generalized members
of the N-confused (1.1.1.1.)-porphyrin series. See Figure 3 in the text.
(3) (a) Furuta, H.; Asano, T.; Ogawa, T. J. Am. Chem. Soc. 1994, 116,
767-768. (b) Ariga, K.; Kunitake, T.; Furuta, H. J. Chem. Soc., Perkin
Trans. 2, 1996, 667-672. (c) Ishikawa, Y.; Yoshida, I.; Akaiwa, K.;
Koguchi, E.; Sasaki, T.; Furuta, H. Chem. Lett. 1997, 453-454. (d) Furuta,
H.; Ishizuka, T.; Osuka, A.; Ogawa, T. J. Am. Chem. Soc. 1999, 121, 2945-
2946. (e) Furuta, H.; Ogawa, T.; Uwatoko, Y.; Araki, K. Inorg. Chem. 1999,
38, 2676-2682.
(4) (a) Chmielewski, P. J.; Latos-Graz˘yn´ski, L.; Rachlewicz, K.;
Glowink, T. Angew. Chem., Int. Ed. Engl. 1994, 33, 779-781. (b)
Chmielewski, P. J.; Latos-Graz˘yn´ski, L. J. Chem. Soc., Perkin Trans. 2,
1995, 503-509. (c) Chmielewski, P. J.; Latos-Graz˘yn´ski, L.: Głowiak, T.
J. Am. Chem. Soc. 1996, 118, 5690-5701. (d) Chmielewski, P. J.; Latos-
Graz˘yn´ski, L. Inorg. Chem. 1997, 36, 840-845. (e) Latos-Graz˘yn´ski, L.
In The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R.,
Eds; Academic Press: San Diego, 1999; Vol. 2, Chapter 14.
(5) (a) Hoo, P.-Y.; Shin, K.; Lee, C.-H. Tetrahedron Lett. 1996, 37,
197-200. (b) Lee, C.-H.; Kim, H.-J. Tetrahedron Lett. 1997, 38, 3935-
3938. (c) Liu, B. Y.; Bru¨ckner, C.; Dolphin, D. J. Chem. Soc., Chem.
Commun. 1996, 2141-2142. (d) Narayanan, S. J.; Sridevi, B.; Srinivasan,
A.; Chandrashekar, T. K.; Roy, R. Tetrahedron Lett. 1998, 39, 7389-7392.
(e) Geier, G. R., III; Lindsey, J. L. J. Org. Chem. 1999, 64, 1596-1603.
Results and Discussion
N2CP (7) was synthesized via the acid-catalyzed condensation
of perfluorobenzaldehyde with N-confused dipyrromethane in
(6) For a general review concerning the design of ligands suitable for
the stabilization of metal complexes in high oxidation states, see: Collins,
T. J. Acc. Chem. Res. 1994, 27, 279-285
10.1021/ja992679g CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/21/2000

804 J. Am. Chem. Soc., Vol. 122, No. 5, 2000
Furuta et al.
Figure 1. X-ray structures of (a) N2CP (7), (b) Ag(III)-N2CP (8), and (c) Cu(III)-N2CP (9). Pentafluorophenyl groups and an ethoxy group were
omitted for clarity in the side views. Selective bond lengths (Å) and angles (deg) are listed in Table 2.
Scheme 1
In this isomer, a cis-like, as opposed to trans-like, arrangement
pertains for each of the confused pyrroles. The preferential
production of this isomer is rationalized in terms of the different
reactivity of the R- and R′-pyrrolic positions in the starting
N-confused dipyrromethane.
When N2CP (7) was treated with Ag(I) acetate in 10%
pyridine/CHCl3 at room temperature, the color of the solution
was observed to change from yellow-green to blue-green, and
over the course of 8 h, a shiny silver-containing product was
obtained quantitatively. Observation of distinct signals in the
1H NMR spectrum in the 10-1 ppm ranges in CDCl3 led to
the inference that this silver-containing product consists of
diamagnetic Ag(III)N2CP (8). The appearance of a signal at
10.37 ppm, ascribable to an outer NH resonance, and the absence
of any signals ascribable to the three inner NH and CH protons,
are considered consistent with this assignment, as were results
from a single-crystal X-ray diffraction analysis (Figure 1b). This
latter study revealed short Ag-C bond distances of 1.987(8)
and 2.011(8) Å, which are comparable with that seen in the
corresponding Ag(III)NCP (3) complex (i.e., 2.03 Å).3e The
complex (8) is nearly square-planar, and the Ag atom is located
in the plane formed by each four donor atoms in the core (two
N and two C).
CHCl3 containing a trace of EtOH (Scheme 1).7 Following
oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ),
a greenish product was purified by silica gel column chroma-
tography to give 7 in ca. 2% yield.8 The spectroscopic data
obtained were consistent with the formulation of ethoxy-
substituted N2CP (7) as a doubly confused isomer of porphyrin.9
1
In particular, two CH signals were observed in the H NMR
spectrum at 3.50 and 3.20 ppm in CDCl3. Such findings are
consistent with a weak aromatic character due to the disruption
of a fully π-conjugated Kekule´ structure. Not surprisingly,
therefore, an upfield NH signal at 6.38 ppm is assigned to the
inner pyrrolic proton; another NH signal, corresponding to the
outer NH proton, was also observed in CDCl3 but only at 8.95
ppm.
More direct evidence for the proposed structure of doubly
confused porphyrin 7 came from a single-crystal X-ray diffrac-
tion analysis (Figure 1a).10 The porphyrin core is slightly
distorted, i.e., the confused pyrrole ring bearing the ethoxy
substituent is canted 18.9° from the mean plane of the 24-atom
core. In contrast, the other confused pyrrole, as well as the two
“normal” pyrroles, are tilted in the opposite direction, by 16.4°,
4.4°, and 7.1°, respectively. On a very different level, the
crystallographic data provided support for the fact that only one
type of N2CP isomer is formed under the reaction conditions.
When Cu(II) acetate was used in place of Ag(I) acetate, a
greenish complex (9) was obtained quantitatively. In analogy
to the Ag(III)N2CP (8) complex, this copper-containing
1
product (9) is EPR silent. Similar to that of 8, the H NMR
spectrum of 9 contains, for instance, a signal at 10.41 ppm that
is ascribable to an outward-pointing NH while displaying no
resonances for the three inner hydrogens. The complex (9) is
nearly square-planar and Cu-C bond distances are 1.939(3) and
1.934(4) Å (Figure 1c), which are comparable to that seen in
the [Cu(CF3)4]- anion (1.949-1.989 Å).11 All of these data
support that the metal oxidation state of 9 is 3+, i.e., Cu(III).
Crystal data for 7-9 and selective bond lengths and angles for
8 and 9 are summarized in Tables 1 and 2, respectively.
Complexes 8 and 9 were also characterized by bands in their
optical absorption spectra that were relatively sharpened com-
pared to those of the starting free base ligand, 7. In particular,
these three species (7-9) display Soret transitions at 424, 442.5,
and 441 nm and Q-bands at 627.5, 620, and 612.5 nm,
(7) Small amounts (ca. 0.5%) of EtOH and bromide anion were found
to be effective for this reaction. An effort with EtOH-free dry CHCl3 to
avoid generating products containing an ethoxy substituent led to only trace
quantities of N2CP.
(8) A corrole-type product was also isolated in 13% yield, which will
be published in due course.
(9) 1H and 13C NMR spectra for 7-9 are given in the Supporting
Information.
(10) We would like to thank Dr. Motoo Shiro (Rigaku Corporation) for
help with the X-ray structural work.
(11) Naumann, D.; Roy, T.; Tebbe, K.-F.; Crump, W. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 1482-1483.

Doubly N-Confused Porphyrin
J. Am. Chem. Soc., Vol. 122, No. 5, 2000 805
Table 1. Crystallographic Details for 7-9
N2CP (7)
Ag-N2CP (8)
Cu-N2CP (9)
emp formula C46H14N4F20O
C46H11N4F20AgO C46H11N4F20CuO
fw
1018.61
1123.46
1079.13
color, habit violet, prismatic brown, prismatic blue, prismatic
cryst syst
monoclinic
monoclinic
P21/n
18.734(3)
8.324(1)
27.674(3)
90.00
monoclinic
P21/n
18.583(3)
8.395(1)
27.732(3)
90.00
space group P21/n
a, Å
18.685(3)
b, Å
8.528(3)
27.866(4)
90.00
c, Å
R, deg
â, deg
γ, deg
V, Å3
107.1270
90.00
4246(2)
4
107.84(1)
90.00
4108.3(9)
4
107.69(1)
90.00
4121.5(9)
4
Z
radiation
(λ, Å)
T, °C
Mo KR (0.71069)
23.0
-150.0
1.816
6.252
-70.0
1.739
6.653
DC, g/cm3
µ, mm-1
diffracto-
meter
1.593
1.579
AFC7S
RAXIS-RAPID RAXIS-RAPID
a
R1
0.062
0.056
1.830
0.071
0.075
1.610
26966
5174
0.059
0.092
1.299
37169
9431
b
wR2
GOF
indep reflns 10399
obsd reflns 3771
(I > 2σ(Ι))
parameters 640
649
650
a R ) Σ||Fo| - |Fc||/Σ|Fo|. b Rw ) [(Σw(|Fo| - |Fc|)2/ΣwFo )]1/2
.
2
Table 2. Selected Bond Lengths (Å) and Bond Angles (deg) for 8
and 9
Ag-N2CP (8)
Cu-N2CP (9)
M-C1
M-C2
M-N3
M-N4
2.011(7)
1.987(9)
2.064(5)
2.047(7)
1.939(3)
1.934(4)
1.969(3)
1.954(4)
C1-M-C2
C2-M-N3
N3-M-N4
N4-M-C1
C1-M-N3
C2-M-N4
86.5(3)
91.6(3)
90.7(2)
91.3(3)
177.6(3)
177.7(2)
85.2(2)
92.0(1)
91.1(1)
91.7(1)
176.2(2)
176.1(1)
respectively (Figure 2). The optical spectrum of free base 7
shows the large solvent shifts, probably due to the interaction
of outward NH and solvents (see Supporting Information).
Comparison between NCP (1) and N2CP (4), with regard to
their ability to coordinate silver and copper cations, reveals the
effect of the second site of pyrrolic confusion upon metal
complexation. In the case of silver complexation, the presence
of similar 3H arrangements in the core of both 1 and 4 suffices
to have both macrocyclic materials act as trianionic ligands,
thereby stabilizing the formation of Ag(III) complexes. In the
case of copper, the NCP ligand serves to coordinate Cu(II),
giving rise to an EPR active Cu(II)NCP complex.12 By contrast,
the doubly confused system N2CP stabilizes a complex contain-
ing a copper(III) center. This marked different ligand-derived
behavior provides an important reflection of the fact that doubly
confused porphyrin 4 can readily act as a trivalent ligand,
stabilizing higher oxidation states. Indeed, at least in certain
circumstances, the presence of a second confusion site serves
to raise the oxidation state of the coordinated metal by one level.
Furthermore, if the outward pointing NH hydrogen of 4 could
be removed by oxidation, either chemically or electrochemically,
Figure 2. Optical absorption spectra of (a) N2CP (7), (b) Ag(III)-
N2CP (8), and (c) Cu(III)-N2CP (9) in CHCl3.
the doubly confused porphyrin, such as N2CP, might be induced
to act as tetraanionic ligands and stabilize neutral M(IV)
complexes (e.g., 6). Further change in metal oxidation states
from “normal” M(II) to M(III) or M(IV) by confusion is of
interest, and a variety of uses for the resulting materials in the
areas of, for instance, electron transfer and/or magnetic switching
studies could be contemplated.
Finally, we would like to propose a general nomenclature
for the N-confused porphyrin family that involves the use of a
(C,N) designation and appropriate R and â suffixes to differenti-
ate the linkage positions. For example, N2CP (7) is 18-porphyrin
(12) A Cu(II) complex was obtained easily from a CN-substituted
N-confused tetraphenylporphyrin (1): EPR parameter (77 K, chloronaph-
thalene) g ) 2.03, 2.05, and 2.132, ACu)25, 25, 169 G, and AN ) 11, 11,
13 G. Private communication from Prof. Y. Ishikawa, Oita University.

806 J. Am. Chem. Soc., Vol. 122, No. 5, 2000
Furuta et al.
Figure 3. Proposed nomenclature for NCPs.
(1.1.1.1.)-(CR,Câ,N,N) (Figure 3). We believe this is one of the
simple methods to identify the confused position of NCP.
Experimental Section
Methods and Materials. Commercially available solvents and
reagents were used without further purification unless otherwise
mentioned. Silica gel column chromatography was performed on
Wakogel C-200. Thin-layer chromatography (TLC) was carried out on
aluminum sheets coated with silica gel 60 (Merck 5554). UV-visible
Conclusion
A doubly N-confused porphyrin (N2CP) and its Ag(III) and
Cu(III) complexes were synthesized for the first time. Both
complexes are diamagnetic and have a square-planar coordina-
tion with two sets of metal-carbon bonds. The trianionic nature
of the N2CP ligand was demonstrated, and a possibility of
stabilizing the higher oxidation state by confusion is suggested.
1
spectra were recorded on a Shimadzu UV-2400PC spectrometer. H
and 13C NMR spectra were recorded on a JEOL R-500 spectrometer
1
(operating as 500.00 MHz for H and 125.65 MHz for 13C) using the
residual solvent as the internal reference. Fast atom bombardment mass

Doubly N-Confused Porphyrin
J. Am. Chem. Soc., Vol. 122, No. 5, 2000 807
spectra (FABMS) were recorded on a JEOL-HX110 in the positive
ion mode with a 3-nitrobenzyl alcohol matrix.
Cu(III) Complex of 2-Ethoxy-5,10,15,20-tetrapentafluorophenyl-
3,7-diaza-21,22-dicarbaporphyrin (Cu(III)-N2CP, 9). To a solution
of ethoxy-substituted tetrapentafluorophenyl-N2CP (7) (20.4 mg, 0.020
mmol) in 20 mL of CHCl3 was added Cu(OAc)2H2O (4.2 mg, 0.021
mmol), and the mixture was stirred at room temperature overnight.
The solution was filtered with a silica gel column to remove excess
copper salt and evaporated. Recrystallization from hexane/CH2Cl2 gave
9 as a green solid in quantitative yield: mp > 300 °C. 1H NMR (CDCl3,
500 MHz, 27 °C): δ (ppm) 10.39 (br, 1H, outer NH), 8.31 (s, 1H,
R-H), 8.08 (d, J ) 4.5 Hz, 2H, â-H), 7.90 (d, J ) 5.5 Hz, 1H, â-H),
7.88 (d, J ) 5.0 Hz, 1H, â-H), 4.58 (br, 2H, CH3CH2O), 1.25 (t, J )
7.0 Hz, 3H, CH3CH2O). 13C NMR (CDCl3, 125.65 MHz, 27 °C): δ
(ppm) 171.52, 150.59, 149.53, 145.99, 143.24, 132.38, 130.73, 130.02,
129.88, 128.72, 124.39, 120.91, 113.70, 110.78, 110.14, 106.55, 64.75
Preparation of meso-Pentafluorophenyl N-Confused Dipyr-
romethane. Confused dipyrromethane was obtained according to the
procedure by Littler et al.13 in 60% yield. 1H NMR (CDCl3, 500 MHz,
27 °C): δ (ppm) 8.19 (s, br, 2H, NH), 6.78 (dd, 1H, R-H), 6.69 (dd,
1H, R-H), 6.50 (s, 1H, R-H), 6.15 (m, 2H, â-H), 5.98 (s, 1H, â-H),
5.82 (s, 1H, meso-H). FABMS: m/z (% intensity) 246.1 (100, M+
-
C4H4N), 312.1 (54, M+).
2-Ethoxy-5,10,15,20-tetrapentafluorophenyl-3,7-diaza-21,22-di-
carbaporphyrin (N2CP, 7). To a solution of N-confused 5-(pentafluo-
rophenyl)dipyrromethane (468 mg, 1.5 mmol) were added pentafluo-
robenzaldehyde (294 mg, 1.5 mmol) and Bu4NBr (242 mg, 0.75 mmol)
in 0.5% EtOH/CHCl3 (750 mL) and BF3OEt2 (189 µL, 1.5 mmol), and
the mixture was stirred for 2 h at room temperature. The reaction
mixture was then passed through a silica gel column and eluted with
CHCl3. To a combined solution, DDQ (896 mg, 2.25 mmol) was added
and stirred for 1 h at room temperature. The green-colored product
was separated by silica gel column chromatography (eluent CH2Cl2/
hexane (3:2)), followed by recrystallization from hexane/CH2Cl2 to give
7 as a green solid in 1-2% yield: Rf ) 0.5 (CH2Cl2); mp > 300 °C.
1H NMR (CDCl3, 500 MHz, 27 °C): δ (ppm) 8.95 (br, 1H, outer NH),
7.36 (d, J ) 5.0 Hz, 1H, â-H), 7.28 (d, J ) 5.5 Hz, 1H, â-H), 7.06 (d,
J ) 5.5 Hz, 1H, â-H), 6.98 (d, J ) 5.0 Hz, 1H, â-H), 6.94 (s, 1H,
R-H), 6.40 (br, 1H, inner NH), 4.33 (q, J ) 7.0 Hz, 2H, CH3CH2O),
3.52 (s, 1H, inner CH), 3.22 (s, 1H, inner CH), 1.12 (t, J ) 7.0 Hz,
3H, CH3CH2O). 13C NMR (CDCl3, 125.65 MHz, 27 °C): δ (ppm)
172.04, 151.44, 134.48 (â-C), 131.49 (â-C), 130.21, 129.18 (â-C),
128.54 (inner C), 128.40 (â-C), 123.24, 121.94 (R-CH), 112.20, 105.01,
104.97 (inner C), 94.59, 65.41 (CH3CH2O), 13.87 (CH3CH2O) (pen-
tafluorophenyl signals could not be assigned because of the multiple
coupling of 13C-19F). UV-vis (CHCl3): λmax [nm] (ꢀ × 10-4) 347.0
(4.1), 424.0 (4.7), 627.5 (1.1), 667.5 (1.0). FABMS: m/z (% intensity)
1018.1 (97, M+), 1019.1 (100, M+ + 1).
Ag(III) Complex of 2-Ethoxy-5,10,15,20-tetrapentafluorophenyl-
3,7-diaza-21,22-dicarbaporphyrin (Ag(III)-N2CP, 8). To a solution
of ethoxy-substituted tetrapentafluorophenyl-N2CP (7) (10.2 mg, 0.01
mmol) in 10 mL of 10% pyridine/CHCl3 was added AgOAc (8.35 mg,
0.05 mmol), and the mixture was stirred at room temperature overnight.
The solution was filtered with a silica gel column to remove excess
silver salt and evaporated. Recrystallization from hexane/CH2Cl2 gave
8 as a green solid in quantitative yield: mp > 300 °C. 1H NMR (CDCl3,
500 MHz, 27 °C): δ (ppm) 10.37 (br, 1H, outer NH), 8.28 (d, J ) 3.0
Hz, 1H, R-H), 8.01 (d, J ) 5.0 Hz, 2H, â-H), 7.83 (d, J ) 5.0 Hz, 2H,
â-H), 4.55 (q, J ) 7.0 Hz, 2H, CH3CH2O), 1.26 (t, J ) 7.0 Hz, 3H,
CH3CH2O). 13C NMR (CDCl3, 125.65 MHz, 27 °C): δ (ppm) 172.53,
172.49, 149.44, 148.54, 144.09, 141.99, 140.95, 132.36, 132.08, 129.87,
129.54, 126.93, 126.87, 123.83, 123.68, 119.72, 114.24, 112.27, 112.14,
112.09, 108.11, 107.58, 65.05 (CH3CH2O), 13.99 (CH3CH2O). UV-
vis (CHCl3): λmax [nm] (ꢀ × 10-4) 368.0 (3.2), 442.5 (4.2), 620.0 (1.7),
676.0 (0.82). FABMS: m/z (% intensity) 1122.25 (76, M+), 1124.26
(100, M+ + 2).
(CH3CH2O), 13.97 (CH3CH2O). UV-vis (CHCl3): λmax [nm] (ꢀ × 10-4
)
368.0 (2.7), 441.0 (4.3), 612.5 (1.4). FABMS: m/z (% intensity) 1078.20
(100, M+).
Single-Crystal Diffraction Analysis. Details of the crystal data are
listed in Table 1. A single crystal of N2CP (7) was obtained by vapor
diffusion of hexane into a CH2Cl2 solution of 7. The data crystal was
a violet prism of approximate dimensions 0.30 mm × 0.20 mm × 0.05
mm. Data were collected at room temperature on a Rigaku AFC7S
diffractometer with graphite monochromated Mo KR radiation (λ )
0.71069 Å). Cell constants and an orientation matrix for data collection
were obtained from a least-squares refinement using the setting angles
of 25 carefully centered reflections in the range 22.0° < 2θ < 24.92°.
A single crystal of Ag(III)N2CP (8) was obtained by vapor diffusion
of hexane into a CH2Cl2 solution of 8. The data crystal was a brown
prism of approximate dimensions 0.15 mm × 0.10 mm × 0.10 mm.
The data were collected at a temperature of -150 ( 1 °C to a maximum
2θ value of 55.0° on a Rigaku RAXISII imaging plate with graphite
monochromated Mo KR radiation (λ ) 0.71069 Å). A total of 147
images, corresponding to 220.5° oscillation angles, were collected. A
single crystal of Cu(III)N2CP (9) was obtained by vapor diffusion of
hexane into CH2Cl2 solution of 9. The data crystal was a blue prism of
approximate dimensions 0.40 mm × 0.40 mm × 0.10 mm. The data
were collected at a temperature of - 70 ( 1 °C to a maximum 2θ
value of 55.0° on a Rigaku RAXISII. A total of 84 images, corre-
sponding to 220.5° oscillation angles, were collected. For all crystals,
the non-hydrogen atoms were refined anisotropically. The calculations
were performed using the teXsan14 crystallographic software package
of the Molecular Structure Corporation.
Supporting Information Available: 1H and 13C NMR
spectra for 7-9, optical absorption spectra of 7, and crystal
structural data for 7-9. This material is available free of charge
via the Internet at http://pubs.acs.org.
JA992679G
(13) Littler, B. J.; Ciringh, Y.; Lindsey, J. S. J. Org. Chem. 1999, 64,
2864-2872.
(14) teXsan for Windows, crystal structure analysis package; Molecular
Structure Corporation, 1997.