Mercury complexes of meso-tetra-(p-cyanophenyl)porphyrin and n-methylporphyrin: Meso-tetra(p-cyanophenyl)porphyrinatomercury(II) and chloro(N-methyl-meso-tetraphenylporphyrinato) mercury(II)

Article abstract of DOI:10.1021/ic010275v

This work for the first time reports X-ray crystals of the two mononuclear mercury(II) porphyrin complexes, i.e., a four-coordinate complex Hg(p-CN)₄tpp (1) and a five-coordinate complex Hg-(N-Me-tpp)Cl (2). Compound 1 is distorted square planar, whereas compound 2 is trigonal bipyramidal distorted square-based pyramid in which the apical site is occupied by a N(1) atom.

Full text of DOI:10.1021/ic010275v

6064
Inorg. Chem. 2001, 40, 6064-6068
a five-coordinate distorted square-based pyramid. M(III) (M )
Mercury Complexes of
Fe,Tl) complexes of N-methylporphyrin with a coordination
number (CN) above 5 are known as well. Utilizing the 1H NMR
characterization, Latos-Grazynski and co-workers10 were able
to demonstrate the existence of low spin (S ) 1/2), six-coordinate
iron(III) complexes of N-methylporphyrins, i.e., [FeIII(N-Me-
ttp)(CN)2], [FeIII(N-Me-ttp)(5-MeIm)2]2+ and [FeIII(N-Me-tmp)-
Im2]2+ (with N-Me-ttp ) N-methyltetra-p-tolylporphyrin mono-
anion, N-Me-tmp ) N-methyltetramesitylporphyrin monoanion,
Im ) imidazole, and 5-MeIm ) 5-methylimidazole). We have
recently reported the crystal structures of diacetato(N-methyl-
meso-tetraphenylporphyrinato)thallium(III), Tl(N-Me-tpp)(OAc)2,11
and bis(trifluoroacetato)-(N-methyl-meso-tetraphenylporphy-
rinato)thallium, Tl(N-Me-tpp)(CF3COO)2.12 The coordination
sphere around the Tl3+ ion is described as an eight-coordinate
square-based antiprism for the former complex and as a 4:3
tetragonal base piano stool seven-coordinate geometry for the
latter complex. Because the coordination numbers and geom-
etries of Hg(II) are known to vary sensitively with the ligand
requirements, it will be of interest to investigate how the larger
d10 Hg(II) ion interacts with the N-CH3Htpp ligand and the
resultant structure out of this interaction. It is observed that the
effective ionic radius (γ) for the metal ion with CN ) 5
increases from 0.82 Å for Zn2+(or 0.81 Å for Co2+, 0.89 Å for
Mn2+, and 0.72 Å for Fe3+) to γ(Hg2+) [1.10 Å < γ(Hg2+) <
1.16 Å].13 To assess the influence of the large mercury(II) cation
on the macrocyclic framework, we report here the first structural
determination of chloro(N-methyl-meso-tetraphenylporphyri-
nato)mercury(II), Hg(N-Me-tpp)Cl (2), by replacing Zn(II), Mn-
(II), Co(II), Fe(II), Fe(III), and Tl(III) with Hg(II).
meso-Tetra-(p-cyanophenyl)porphyrin and
N-methylporphyrin: meso-
Tetra(p-cyanophenyl)porphyrinatomercury(II)
and Chloro(N-methyl-meso-
tetraphenylporphyrinato)mercury(II)
Ming-Cheng Wang, Long-Seen Sue, Bing-Chung Liau,
Bao-Tsan Ko, Shanmugham Elango, and
Jyh-Horung Chen*
Department of Chemistry, National Chung-Hsing University,
Taichung 40227, Taiwan, R.O.C.
ReceiVed March 12, 2001
Introdution
Several examples of mercury porphyrin complexes have been
formulated, but no X-ray structural data were available until
1979.1-3 In 1974, Hudson et al.1 reported the reaction of meso-
tetraphenylporphyrin, H2tpp, with slightly more than one
equivalent of mercury(II) acetate in methylene chloride-THF
yielding the “normal” monometallic complex, meso-tetraphen-
ylporphyrinatomercury(II) Hgtpp. Because of the difficulties in
obtaining a crystal suitable for absolute structural assignment
by X-ray method, Hudson and co-workers1-3 characterized the
complex Hgtpp by UV, elemental analysis, and mass spectrum.
In 1979, a homodinuculear structure was proposed for the
bischloromercury(II) complex of N-tosylaminooctaethylporphy-
rin, C43H51N5O2SCl2Hg2, which represented the first X-ray
structural proof for the existence of mercury(II) porphyrin
sitting-atop (SAT) complexes.4 However, still no direct X-ray
structural data of mononuclear mercury(II) porphyrin have been
published so far. meso-Tetra-(p-cyanophenyl)porphyrinatomer-
cury(II), Hg(p-CN)4tpp (1), is a homologue of Hgtpp which is
a four-coordinate Hg(II) porphyrin complex. In this paper, we
describe the formation and present the crystal structure of this
new, mononuclear mercury(II) porphyrin complex 1.
Experimental Section
Hg(p-CN)4tpp (1). A mixture of H2(p-CN)4tpp (200 mg, 2.8 × 10-4
mol) in CH2Cl2 and Hg(OAc)2 (133.89 mg, 4.2 × 10-4 mol) in MeOH
was refluxed for 1 h. After concentrating, the residue was crystallized
from CH2Cl2/MeOH [1:1 (v/v)] as a deep blue solid of 1. Crystals were
1
grown by diffusion of ether vapor into a CH2Cl2 solution. H NMR
(599.95 MHz, CD2Cl2, 20 °C): δ 8.83 [s, â-pyrrole H or Hâ]; 8.35 [d,
3J(H-H) ) 8.4 Hz], and 8.33 [d, 3J(H-H) ) 8.4 Hz] for ortho protons;
3
Several first-row transition metal complexes of N-substituted
8.09 [d, J(H-H) ) 7.8 Hz, meta protons]. MS, m/z (assignment, rel
porphyrin MII(N-Me-tpp)Cl [M ) Zn (S ) 0),5 Co (S ) 3/2),6,7
intensity): 914 ([Hg(p-CN)4tpp + H]+, 1.23); 715 ([H2(p-CN)4tpp]+,
19.37); 714 ([H(p-CN)4tpp]+, 15.30). UV/visible spectrum, λ (nm)
[ꢀ × 10-2 (M-1 cm-1)] in CH2Cl2: 420 (416), 514 (30.4), 546 (18.5),
589 (15.5).
5
Mn (S ) /2),8 Fe (S ) 2),9 and tpp ) 5,10,15,20-tetraphen-
ylporphyrinate] have been extensively studied by Anderson et
al. and [FeIII(N-Me-ttp)Cl][SbCl6] (S ) 5/2) (N-Me-tpp )
N-methyl tetra-p-tolylporphyrin monoanion) was reported by
Latos-Grazynski and co-workers.10 The common feature in all
of these N-substituted metalloporphyrins is that the metal atom
is no longer coplanar with the four nitrogen atoms of the
macrocycle and coordination geometry around the metal ion is
Hg(N-Me-tpp)Cl (2). A mixture of N-CH3Htpp (0.40 g, 6.22 × 10-4
mol) in CHCl3 (50 cm3) and HgCl2 (0.50 g, 1.87 × 10-3 mol) in MeOH
(5 cm3) was refluxed for 5 h. After concentrating, the residue was
dissolved in CHCl3 and filtered through Celite. The filtrate was
concentrated to yield a green solid of 2 (0.44 g, 5.09 × 10-4 mol,
81.8%). Compound 2 was redissolved in CHCl3 and layered with MeOH
to afford green crystals for single-crystal X-ray analysis. 1H NMR
(599.95 MHz, CDCl3, 20 °C): δ 8.91 [s, Hâ(13,14), 4J(Hg-H) )
22 Hz], where Hâ(a,b) represents the two equivalent â-pyrrole
protons attached to carbons a and b, respectively; 8.77 [d, Hâ(8,19),
* To whom correspondence should be addressed.
(1) Hudson, M. F.; Smith, K. M. Tetrahedron Lett. 1974, 2227.
(2) Hudson, M. F.; Smith, K. M. Tetrahedron Lett. 1974, 2223.
(3) Hudson, M. F.; Smith, K. M. Tetrahedron 1976, 32, 597.
(4) Callot, H. J.; Chevrier, B.; Weiss, R. J. Am. Chem. Soc. 1979, 101,
7729.
3
3J(H-H) ) 4.2 Hz]; 8.66 [s, Hâ(9,18), J(H-H) ) 4.8 Hz]; 8.00 [s,
Hâ(3,4)]; 8.58 (s) and 8.26 (s) for ortho protons, i.e., H (28,32); 8.32
(s) and 8.12 (s) for ortho protons, i.e., H (34,38); 7.74-7.88 [m, meta
(5) Lavellee, D. K.; Kopelove, A. B.; Anderson, O. P. J. Am. Chem. Soc.
1978, 100, 3025.
(6) Anderson, O. P.; Lavellee, D. K. J. Am. Chem. Soc. 1976, 98, 4670.
(7) Anderson, O. P.; Lavellee, D. K. J. Am. Chem. Soc. 1977, 99, 1404.
(8) Anderson, O. P.; Lavellee, D. K. Inorg. Chem. 1977, 16, 1634.
(9) Anderson, O. P.; Kopelove, A. B.; Lavellee, D. K. Inorg. Chem. 1980,
19, 2101.
(10) Balch, A. L.; Cornman, C. R.; Latos-Grazynski, L.; Olmstead, M. M.
J. Am. Chem. Soc. 1990, 112, 7552.
(11) Tung, T. Y.; Chen, J. H.; Liao, F. L.; Wang, S. L.; Hwang, L. P.
Inorg. Chem. 2000, 39, 2120.
(12) Yang, C. H.; Tung, J. Y.; Liau, B. C.; Ko, B. T.; Elango, S.; Chen, J.
H.; Hwang, L. P. Personal communication.
(13) Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry, 4th
ed.; Harper Collins College: New York, 1993; p 114.
10.1021/ic010275v CCC: $20.00 © 2001 American Chemical Society
Published on Web 10/02/2001

Notes
Inorganic Chemistry, Vol. 40, No. 23, 2001 6065
Table 1. Crystal Data for Hg(p-CN)4tpp (1) and
Hg(N-Me-tpp)Cl‚CH2Cl2 (2‚CH2Cl2)
Table 2. Selected Bond Distances (Å) and Angles (deg) for
Compounds Hg(p-CN)4tpp 1 and Hg(N-Me-tpp)Cl‚CH2Cl2
(2‚CH2Cl2)
empirical formula C48H24HgN8 (1)
C46H33Cl3HgN4 (2‚CH2Cl2)
fw
913.34
P1h
948.70
P1h
Hg(p-CN)4tpp (1)
space group
cryst syst
a, Å
Distances
triclinic
9.968(1)
12.666(1)
16.783(2)
71.756(2)
80.519(2)
84.567(2)
1983.0(4)
2
triclinic
12.6343(9)
13.3035(9)
13.952(1)
67.650(1)
88.698(1)
64.591(1)
1931.3(2)
2
Hg-N(1)
Hg-N(2)
2.177(6)
2.255(6)
Hg-N(3)
Hg-N(4)
2.169(6)
2.212(6)
b, Å
c, Å
Angles
N(1)-Hg-N(2)
N(1)-Hg-N(3)
N(1)-Hg-N(4)
84.9(2)
152.3(3)
86.9(2)
N(2)-Hg-N(3)
N(2)-Hg-N(4)
N(3)-Hg-N(4)
86.7(2)
148.4(3)
86.6(2)
R, deg
â, deg
γ, deg
V, Å3
Z
Hg(N-Me-tpp)Cl‚CH2Cl2 (2‚CH2Cl2)
F000
D
896
1.530
39.26
0.801
936
1.631
42.32
0.955
Distances
calcd, g cm-3
Hg-N(2)
Hg-N(3)
Hg-N(4)
2.370(3)
2.190(3)
2.380(3)
Hg-Cl
Hg-N(1)
2.333(1)
2.807
µ(Μï ΚR), cm-1
S
cryst size, mm3
2θmax, deg
T, K
0.10 × 0.12 × 0.18 0.28 × 0.55 × 0.70
Angles
50.06
51.94
293(2)
10784
7382(I>2σ(I))
3.54
Cl-Hg-N(2)
Cl-Hg-N(3)
Cl-Hg-N(4)
N(2)-Hg-N(3)
N(2)-Hg-N(4)
113.53(9)
149.22(9)
111.05(9)
80.2(1)
N(3)-Hg-N(4)
80.2(1)
92.9
71.7
117.8
70.6
293(2)
Cl-Hg-N(1)
no. of reflns measd 10475
N(1)-Hg-N(2)
N(1)-Hg-N(3)
N(1)-Hg-N(4)
no. of reflns obsd
6924(I>2σ(I))
4.74
11.39
Ra (%)
121.9(1)
Rwb (%)
10.43
a R ) [∑||Fo|-|Fc||/∑|Fo|]. b Rw ) [∑w(||Fo|-|Fc||)2/∑w(|Fo|)2]1/2
;
N(1)-N(4)] are labeled as ∆24 and ∆4N, respectively. The Hg
atom is 0.64/0.56 Å (i.e., ∆24/∆4N) out of the porphyrin or
4N plane. The dihedral angles between the mean plane (C20N4)
and the plane of the phenyl groups are 80.5° [C(24)], 48.5°
[C(30)], 50.5° [C(36)], and 49.4° [C(42)]. The radius of the
central “hole” [Ct′‚‚‚N, the distance from the geometrical center
(Ct′) of the mean plane of the 24-atom core to the porphyrinato-
core N atoms] is 2.132 Å, which is larger than 2.01 Å as
suggested by Collin and Hoard.14 The mercury(II) is bonded in
a highly expanded porphyrinato core (C20N4). Figure S1a (in
the Supporting Information) illustrates the displacement (in Å)
of each atom of the porphyrin (C20N4 and Hg) from the
porphyrin mean plane (C20N4) and the mean 4N plane. The large
metal ions, such as mercury(II), cannot fit well into the
porphyrin core and just sit out-of-plane in the metalloporphyrin.
It will be interesting to compare the structure of 1 with its
analogous Zn(II) porphyrin complex. Zn(II)(γ ) 0.74 Å) in Zn-
(tpp)‚2C6H5CH3 15 and Hg(II) (γ ) 1.12 Å) in 1 with CN ) 4
are situated apart from the 4N plane by 0 and 0.56 Å,
respectively. This large displacement was expected because of
the large size of the Hg. Compound 1 appears to show C4 axial
symmetry in solution. Hence, only one kind of Hâ, meta protons,
Câ, CR, Cm, and phenyl-C1 were observed for 1 in CDCl3 at
20 °C.
w ) A/(σ2Fo + BFo ).
2
and para protons]; -4.27 [s, N-Me]. UV/visible spectrum, λ (nm)
[ꢀ × 10-3(M-1cm-1)] in CH2Cl2: 459 (84.8), 570(10.5), 618 (16.0),
666 (11.7).
Spectroscopy. Proton and 13C NMR spectra were recorded at 599.95
and 150.87 MHz, respectively on Varian Unity Inova-600 spectrometers
locked on deuterated solvent and referenced to the solvent peak. Proton
NMR is relative to CD2Cl2 or CDCl3 at δ ) 5.30 or 7.24 and 13C NMR
to the center line of CD2Cl2 or CDCl3 at δ ) 53.6 or 77.0. HMQC
(heteronuclear multiple quantum coherence) was used to correlate
protons and carbon through one-bond coupling and HMBC (hetero-
nuclear multiple bond coherence) for two- and three-bond proton-
carbon coupling. Nuclear Overhauser effect (NOE) difference spec-
troscopy was employed to determine the 1H-1H proximity through
space over a distance of up to about 4 Å.
The positive-ion fast atom bombardment mass spectrum (FAB MS)
was obtained in a nitrobenzyl alcohol (NBA) matrix using a JEOL JMS-
SX/SX 102A mass spectrometer. UV/visible spectra were recorded at
25 °C on a HITACHI U-3210 spectrophotometer.
Crystallography. Table 1 presents the crystal data as well as other
information for Hg(p-CN)4tpp (1) and Hg(N-Me-tpp)Cl‚CH2Cl2 (or
2‚CH2Cl2). Measurements were taken on a Bruker AXS SMART-1000
diffractometer using monochromatized Mo KR radiation (λ ) 0.710 73
Å). The SADABS absorption corrections were made for 2. The
structures were solved by direct methods (SHELXTL PLUS) and refined
by the full-matrix least-squares method. All non-hydrogen atoms were
refined with anisotropic thermal parameters, whereas all hydrogen atom
positions were calculated using a riding model and were included in
the structure factor calculation. Table 2 lists selected bond distances
and angles for both complexes.
Molecular Structure of 2. Figure 1b illustrates the skeletal
framework of complex 2‚CH2Cl2. The geometrical configuration
around the Hg2+ is described as a distorted square-based pyramid
in which the N(1) atom occupies the apical site, whereas the
three nitrogen atoms [N(2), N(3), and N(4)] and one chlorine
atom Cl define the basal plane. The unusual bond distances and
angles are summaried in Table 2.
Results and Dicussion
Crystal Structure of Hg(p-CN)4tpp (1). The molecule is a
four-coodinate mercury with four nitrogen atoms of the por-
phyrin (Figure 1a). The most interesting bond distances and
angles of the mercury(II) atom with respect to the ligand are
summarized in Table 2. The covalent mercury-nitrogen bond
distances are [Hg-N(1) ) 2.177 (6), Hg-N(2) ) 2.255 (6),
Hg-N(3) ) 2.169 (6), and Hg-N(4) ) 2.212 (6) Å], which
are close to the sum of the Hg and N covalent radii (2.23 Å).
The geometrical configuration around the Hg(II) is markedly
distorted from square planar to tetrahedron.
According to Grdenic,16,17 the mercury coordination sphere
can be categorized in terms of their primary, or characteristic,
(m; m ) number of covalently bonded atoms) and effective
coordination (m + n, the total number of primary and secondary
bonds; n ) number of atoms at distances greater than the sum
of the covalent radii but less than or equal to the sum of the
(14) Collins, D. M.; Hoard, J. L. J. Am. Chem. Soc. 1970, 92, 3761.
(15) Scheidt, W. R.; Kastner, M. E.; Hatano, K. Inorg. Chem. 1978, 17,
706.
(16) Grdenic, D. Quart. ReV. 1965, 19, 303.
(17) Matkovic-Calogovic, D.; Davidovic, N.; Popovic, Z.; Zugaj, Z. Acta
Crystallogr. 1998, C54, 1766.
The displacements of the metal center from the planes of the
macrocycle atoms (C20N4) and the four porphyrin nitrogens [i.e.,

6066 Inorganic Chemistry, Vol. 40, No. 23, 2001
Notes
N(3), and N(4) are bonded strongly as well as covalently to the
Hg atom in 2. Mecury(II) is bonded to fewer than four nitrogen
atoms, and so compound 2 may be considered as a sitting-atop
(SAT) complex. The similar kind of SAT complex was
previously reported for bischloromercury(II) complex of N-
tosylaminooctaethylporphyrin.4 Although the primary (or char-
acteristic) coordination environment around the mercury atom
in 2 is tentatively assigned as a SAT complex, the Hg‚‚‚N(1)
distance of 2.807 Å is longer than 2.75(2) Å but is signficantly
shorter than the sum of the van der Waals radii of Hg and N
(3.28 Å). This longer Hg‚‚‚N(1) contact is described as weak
(secondary) bond. This kind of secondary bonds have been
found between Hg(2) and N(1) [Hg(2)-N(1) 2.99 (1) Å] in
[{Hg(C6H4C5H4N)}2(tuc)] (tuc2- ) 2-thiouracilate dianion),22
and with a Hg‚‚‚N distance of 2.89 (1) Å in bis[2-((dimethyl-
amino)methyl)phenyl]mercury(II).23 The effective coordination
around mercury in 2 may be construed as an expansion of the
secondary valency of mercury from four to five {4 + 1[N(1)]}.
The distortion in five-coordinate complexes can be quantified
by the “degree of trigonality” which is defined as τ ) (â -
R)/60, where â is the largest and R the second largest of the
Lbasal-M-Lbasal angles.24,25 In the present case, we find â )
149.22(9)° [N(3)-Hg-Cl] and R ) 121.9(1)° [N(2)-Hg-
N(4)], and thus, τ ) 0.46; the limiting values are τ ) 0 for an
ideal tetragonal geometry and τ ) 1 for an ideal trigonal-
bipyramidal geometry. Hence, the geometry around Hg(II) is
best described as a distorted square-based pyramid (or trigonal
bipyramidal distorted square-based pyramid, TBPDSBP)26 with
N(1) as the apical atom (Figure S2 in the Supporting Informa-
tion). The τ values calculated for Zn(N-Me-tpp)Cl,5 Co(N-Me-
tpp)Cl,6,7 Mn(N-Me-tpp)Cl,8 Fe(N-Me-tpp)Cl,9 and [FeIII(N-Me-
ttp)Cl][SbCl6]10 by the same method are 0.05, 0.02, 0.09, 0.06,
and 0.09, respectively, and the coordination geometry for these
five compounds is closer to regular square-based pyramid
(RSBP)27 with a chloride ion axially coordinated to the metal.
We adopt the plane of three strongly bound pyrrole nitrogen
atoms [i.e., N(2), N(3), and N(4)] as a reference plane 3N. Figure
S1b (in the Supporting Information) illustrates the displacement
(in Å) of each atom of the porphyrin (C20N4, Hg, N-Me, and
Cl-) from the 3N plane. Because of the larger size of the
mercury(II) ion, Hg is considerably pushed away from the 3N
plane; its displacement of 1.13 Å is in the same direction as
that of the apical Cl- ligand [cf. 0.65 Å for Zn(II) in Zn(N-
Me-tpp)Cl,5 0.56 Å for Co(II) in Co(N-Me-tpp)Cl,6,7 0.69 Å
for Mn(II) in Mn(N-Me-tpp)Cl,8 0.62 Å for Fe(II) in Fe(N-Me-
tpp)Cl,9 and 0.57 Å for Fe(III) in [FeIII(N-Me-ttp)Cl][SbCl6].10
The porphyrin macrocycle is indeed distorted [Figure S1b in
the Supporting Information] as a result of the N-Me group. The
pyrrole N(1) [i.e., plane of N(1), C(2)-C(5)] bearing the methyl
group is the most deviated one from the 3N plane, making a
dihedral angle of 39.1°, whereas smaller angles of 16.2°, 15.3°,
and 0.3° occur with pyrroles N(2), N(4), and N(3), respectively.
Figure 1. Molecular configuration and atom-labeling scheme for (a)
Hg (p-CN)4tpp(1) and (b) Hg(N-Me-tpp)Cl‚CH2Cl2 (or 2‚CH2Cl2), with
ellipsoids drawn at 30% probability. Hydrogen atoms for both
compounds and solvent C(60)H(60A)H(60B)Cl(1)Cl(2) for 2‚CH2Cl2
are omitted for clarity.
appropriate van der Waals radii). The effective coordination is
then denoted as [m + n].18 The Hg-Cl bond distance of 2.333
(1) Å is smaller than the sum of the covalent radii of Hg and
Cl (2.47 Å). The covalent bond of Hg-Cl ) 2.333 (1) Å in 2
is comparable to those of Hg(1)-Cl(1) ) 2.318 (2) Å and Hg-
(2)-Cl(2) ) 2.285 (2) Å in bischloromercury(II) complex of
N-tosylaminooctaethylporphyrin4 and that of Hg(1)-Cl(1) )
2.318 (1) Å in Hg(Stpp)Cl (Stpp ) tetraphenyl-21-thiaporphyrin
anion).19 The mercury-nitrogen bond distances [Hg-N(2) )
2.370 (3), Hg-N(3) ) 2.190 (3), and Hg-N(4) ) 2.380 (3)
Å] which are close to the sum of the Hg and N covalent radii
(2.23 Å) are also smaller than the upper limit 2.75 (2) Å for
the typical covalent bond distance of Hg-N.20,21 Hence, N(2),
(21) Canty, A. J.; Chaichit, N.; Gatehouse, B. M.; George, E. E. Inorg.
Chem. 1981, 20, 4293.
(22) Casas, J. S.; Castellano, E. E.; Garcia-Tasende, M. S.; Sanchez, A.;
Sordo, J.; Vazquez-Lopez, E. M.; Zuckerman-Schpector, J. J. Chem.
Soc., Dalton Trans. 1996, 1973.
(23) Atwood, J. L.; Berry, D. E.; Stobart, S. R.; Zaworotko, M. J. Inorg.
Chem. 1983, 22, 3480.
(24) Addison, A. W.; Rao, T. N.; Reedijk, J.; Rijn, J. V.; Verschoor, G. C.
J. Chem. Soc., Dalton Trans. 1984, 1349.
(18) Wright, J. G.; Natan, M. J.; MacDonnell, F. M.; Ralston, D. M.;
O’halloran, T. V. Prog. Inorg. Chem. 1990, 38, 323.
(19) Tung, J. Y.; Liau, B. C.; Elango, S.; Chen, J. H.; Liao, F. L.; Wang,
S. L.; Hwang, L. P. Personal communication.
(25) Garvey, R. G.; Koob, R. O.; Morris, M. L. Acta Cryst. 1987, C43,
2056.
(26) Murphy, G.; Nagle, P.; Murphy, B.; Hathaway, B. J. Chem. Soc.,
Dalton Trans. 1997, 2645.
(20) Canty, A. J.; Chaichit, N.; Gatehouse, B. M.; George, E. E.; Hayhurst,
G. Inorg. Chem. 1981, 20, 2414.
(27) O’sullivan, C.; Murphy, G.; Murphy, B.; Hathaway, B. J. Chem. Soc.,
Dalton Trans. 1999, 1835.

Notes
Inorganic Chemistry, Vol. 40, No. 23, 2001 6067
Such a large deviation from planarity is also reflected for pyrrole
N(1) by observing a 9.5-10.6 ppm upfield shift of Câ(3,4) at
122.5 ppm, compared to 132.0 ppm for Câ(8,19), 133.08 ppm
for Câ(9,18), and 133.11 ppm for Câ(13,14) at 20 °C. Similarly
the nonplanarity of porphyrin causing upfield shifts of Câ
resonances were also observed with a magnitude of 5.6-7.0
ppm for Tl(N-Me-tpp)(OAc)2.11 The dihedral angles between
the mean plane of the skeleton 3N and the planes of the phenyl
groups are 34.5° [C(24)], 36.2° [C(30)], 63.8° [C(36)], and 72.7°
[C(42)].
The Hg ion is displaced from the plane of the four individual
pyrrole groups, suggesting that the pyrrole nitrogen lone pairs
are not optimally situated for covalent bonding to the metal.
The displacements of Hg ions from the plane of each pyrrole
ring are 0.50 Å for pyrrole N(2) ring, 1.13 Å for pyrrole N(3),
0.55 Å for pyrrole N(4), and 2.64 Å for pyrrole N(1) ring. The
angles between Hg-N vector and the corresponding pyrrole
ring are 13.9° for pyrrole N(2) ring, 30.6° for pyrrole N(3),
14.7° for pyrrole N(4), and 70.2° for pyrrole N(1) ring.
1H and 13C of 2 in CDCl3 and CD2Cl2. Complex 2 was
thoroughly characterized by 1H (Figure 2) and 13C NMR spectra.
In solution, compound 2 has effective Cs symmetry, with the
mirror plane running through the C(45)-N(1)-Hg-Cl-N(3).
There are four â-pyrrole protons Hâ, four â-pyrrole carbons Câ,
four R-pyrrole carbons CR, two different meso carbons Cmeso
,
and two phenyl-C1 carbons. The Hâ(13,14) of 2 in CDCl3 at 20
°C was observed at δ ) 8.91 ppm with a 4J(199Hg-H) value of
22 Hz (Figures S3-S6 in the Supporting Information). This
4
coupling satellites is comparable to J(199Hg-H) values of 20
and 24 Hz for the Hd protons in [Hg(TMPA)](ClO4)2 28 and in
[Hg(BMPA)NCCH3](ClO4)2,29 respectively, {with TMPA )
tris[(2-pyridyl)methyl]amine and BMPA ) bis[(2-pyridyl)meth-
yl]amine} and that of 16 Hz in Hg(Stpp)Cl.19 The singlet at
8.00 ppm assigned to Hâ(3,4) is confirmed by NOE difference
spectrum (1-D). We irradiated N-Me at δ ) -4.27 and observed
the enhancement for Hâ(3,4) (Figure S3 in the Supporting
Information). The average distance between Hâ(3,4) and phenyl-
ortho protons of o-H(28,32) [or o-H(22,26)] is 3.43 Å, and the
same between those ortho protons and Hâ(8,19) is 3.46 Å.
Irradiation of Hâ(3,4) strongly enhanced ortho protons of
o-H(28,32) at 8.58 and 8.26 ppm (Figure S4 in the Supporting
Information). Likewise, irradiation of o-H(28,32) at 8.58 ppm
resulted in enhancement of both Hâ(8,19) at 8.77 ppm and
Hâ(3,4) at 8.0 ppm (Figure S4 in the Supporting Information).
The average distance between Hâ(13,14) and phenyl-ortho
protons of o-H(34,38) [or o′-H(40,44)] is 3.42 Å. Irradiation of
Hâ(13,14) enhanced ortho protons of o′-H(34,38) at δ ) 8.32
and 8.12 ppm (Figure S6 in the Supporting Information).
Figure 2 depicts the representative 1H spectra for 2 in CD2Cl2
solvent at +20 and -90 °C. At 20 °C, the rotation of phenyl
group along the C1-Cmeso bond is intermediately slow. This
intermediately slow rotation is supported by assigning the two
broad singlets at 8.23 (or 8.12) and 8.59 (or 8.31) ppm to ortho
protons o′-H(28,32) [or o′-H(34,38); Figure 2a]. At -90 °C,
this rotation is extremely slow. Hence, the rate of intramolecular
exchange of the ortho protons for 2 in CD2Cl2 is also extremely
slow. The doublet at 8.62 ppm is assigned to ortho protons
o-H(28) [or o-H(26)] with 3J(H-H) ) 7.3 Hz (Figure 2b). The
other doublet at 8.22 ppm is due to ortho protons o-H(32) [or
o-H(22)] with 3J(H-H) ) 7.3 Hz. Likewise, the doublet at 8.32
Figure 2. 1H NMR spectra for 2 at 599.95 MHz in CD2Cl2 showing
four different â-pyrrole protons Hâ and phenyl protons (o-H, m, p-H):
(a) 20 °C and (b) -90 °C.
ppm is due to the ortho protons o′-H(34) [or o′-H(44)]
3
with J(H-H) ) 6.8 Hz. The corresponding doublet at 8.09
ppm is due to the ortho protons o′-H(38) [or o′-H(40)] with
3J(H-H) ) 6.8 Hz (Figure 2b). In a similar way, the meta and
para protons appearing as multiplet (7.79-7.89 ppm) at 20 °C
3
(Figure 2a) changed to 7.92 [t, J(H-H) ) 7.4 Hz, m-H(29)],
7.85 [t, 3J(H-H) ) 7.4 Hz, m-H(31)], 7.81 [t, 3J(H-H) ) 7.6
Hz, p-H(30)], 7.77 [m, m-H(35,37)], and 7.72 ppm [m, p-H(36)]
at -90 °C (Figure 2b). The analysis of this data was confirmed
by the NOE difference spectroscopy for 2 in CD2Cl2 at -90
°C (Figures S7-S15 in the Supporting Information). In addition,
the unambiguous assignment of 13C NMR in CD2Cl2 at -90
°C were shown in the Supporting Information (page S16).
The change in orientation of the pyrrole N(1) ring in 2 is the
result of altered hybridizaton at the pyrrole nitrogen atom N(1)
(28) Bebout, D. C.; Ehmann, D. E.; Trinidad, J. C.; Crahan, K. K.; Kastner,
M. E.; Parrish, D. A. Inorg. Chem. 1997, 36, 4257.
(29) Bebout, D. C.; Delanoy, A. E.; Ehmann, D. E.; Kastner, M. E.; Parrish,
D. A.; Butcher, R. J. Inorg. Chem. 1998, 37, 2952.

6068 Inorganic Chemistry, Vol. 40, No. 23, 2001
Notes
from sp2 for 1 to sp3 for 2. The rehybridization of the substituted
porphyrin nitrogen atom and steric bulk of the substituted methyl
group lead to a large displacement of the Hg ion above the 4N
plane toward the chloro ligand in 2. Furthermore, the ionic radius
of Hg2+ is larger in 2 than in 1. Hg is found to be 1.19 Å above
this 4N plane in 2, and the corresponding displacement was
0.56 Å for Hg in 1 (Figure S1 in the Supporting Information).
Acknowledgment. The financial support from the National
Science Council of the R.O.C. under Grant NSC 89-2113-M-
005-023 is gratefully acknowledged.
Supporting Information Available: Figure S1 shows the diagram
of porphyrinato core for both complexes. Figure S2 illustrates the
oriented X-ray geometry of 2 to show a trigonal bipyramidal distorted
square-based pyramidal structure. Figures S3-S15 consist of the NOE
difference spectroscopy for compound 2 in CDCl3 at 20 °C and in
CD2Cl2 at -90 °C. The X-ray crystallographic files in CIF format for
compounds 1 and 2 are also depicted. This material is available free
of charge via the Internet at http://pubs.acs.org.
Conclusions
We have investigated the first two diamagnetic and mono-
nuclear mercury(II) porphyrin complexes 1 and 2 and their X-ray
structures are established. The NOE difference spectroscopy,
HMQC, and HMBC were employed to unambiguous assignment
of the 1H and 13C NMR resonances of 2 in CD2Cl2 at -90 °C.
IC010275V