Syntheses and structures of mono-thiocyanate complexes of cadmium(II) and lead(II) containing bulky nitrogen based polydentate ligands

Article abstract of DOI:10.1016/S0277-5387(02)01058-6

The reaction of [Cd₂(thf)₅](BF₄)₄ with two equiv. of T1[HB(3-Bu^tpz)₃] (pz = pyrazolyl ring) produces the intermediate {[HB(3-Bu^tpz₃]Cd}[BF₄] that reacts with potassium thiocyanate to yield [HB(3-Bu^tpz)₃]Cd(NCS) (1). The solid state structure shows that the sterically demanding 3-tert-butyl groups enforce the formation of a tetrahedral, monomeric complex, the first four-coordinate cadmium(II)-thiocyanate complex to be structurally characterized. The decomposition of this compound produced [(Bu^tHpz)₂Cd(NCS)₂]_n (2) as shown by X-ray crystallography. It was not possible to form a lead(II) complex analogous to 1, but using less sterically demanding ligands allowed the preparation of {[HB(3,5-Me₂pz)₃]Pb(μ-NCS)}₂ (3), and {[HB(pz)₃]Pb(μ-NCS)}_n (4). The former has a dimeric structure with both μ-NCS-S,N and μ-NCS-S,S bridging SCN^- ligands and the latter has a infinite 2-D layered array in which three nonequiv. {[HB(pz)₃]Pb}⁺ groups sandwich a layer of SCN^- ligands. Using neutral 2,6-pyridyl-diimine ligands (pydim) having bulky 2,6-dimethylphenyl substituents, parallel complexes of both metals were prepared. The cadmium complex, [(pydim)Cd (NCS)]₂[BF₄]₂ (5) is dimeric with normal μ-NCS-S,N bridging groups. The structure of the lead(II) analog, [(pydim)Pb(NCS)][BF₄] (6) is monomeric with an N-bound, isothiocyanate ligand and a four-coordinate lead(II). The structure of 6 is very different from 5, presumably because of the stereoactive lone pair on lead(II).

Full text of DOI:10.1016/S0277-5387(02)01058-6

Polyhedron 21 (2002) 1795ꢃ1807
/
www.elsevier.com/locate/poly
Syntheses and structures of mono-thiocyanate complexes of
cadmium(II) and lead(II) containing bulky nitrogen based
polydentate ligands
Daniel L. Reger a,*, Terri D. Wright a, Mark D. Smith a, Arnold L. Rheingold b,
Scott Kassel b, Thomas Concolino b, Brian Rhagitan b
a Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
b Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
Received 14 January 2002; accepted 13 May 2002
Abstract
The reaction of [Cd2(thf)5](BF4)4 with two equiv. of Tl[HB(3-Butpz)3] (pzꢀ
/
pyrazolyl ring) produces the intermediate {[HB(3-
Butpz3]Cd}[BF4] that reacts with potassium thiocyanate to yield [HB(3-Butpz)3]Cd(NCS) (1). The solid state structure shows that
the sterically demanding 3-tert-butyl groups enforce the formation of a tetrahedral, monomeric complex, the first four-coordinate
cadmium(II)-thiocyanate complex to be structurally characterized. The decomposition of this compound produced
[(But Hpz)2Cd(NCS)2]n (2) as shown by X-ray crystallography. It was not possible to form a lead(II) complex analogous to 1,
but using less sterically demanding ligands allowed the preparation of {[HB(3,5-Me2pz)3]Pb(m-NCS)}2 (3), and {[HB(pz)3]Pb(m-
NCS)}n (4). The former has a dimeric structure with both m-NCS-S,N and m-NCS-S,S bridging SCNꢁ ligands and the latter has a
infinite 2-D layered array in which three nonequiv. {[HB(pz)3]Pb}ꢂ groups sandwich a layer of SCNꢁ ligands. Using neutral 2,6-
pyridyl-diimine ligands (pydim) having bulky 2,6-dimethylphenyl substituents, parallel complexes of both metals were prepared. The
cadmium complex, [(pydim)Cd (NCS)]2[BF4]2 (5) is dimeric with normal m-NCS-S,N bridging groups. The structure of the lead(II)
analog, [(pydim)Pb(NCS)][BF4] (6) is monomeric with an N-bound, isothiocyanate ligand and a four-coordinate lead(II). The
structure of 6 is very different from 5, presumably because of the stereoactive lone pair on lead(II). # 2002 Elsevier Science Ltd. All
rights reserved.
Keywords: Tris(pyrazolyl)borate and 2,6-pyridyl-diimine ligands; Thiocyanate; Cadmium(II); Lead(II)
1. Introduction
We have expanded this chemistry to include the
ambidentate thiocyanate ligand. A variety of thiocya-
nate complexes of these two metals have been prepared,
mainly with neutrally charged nitrogen based co-ligands
and the thiocyanate ligand has been shown to bond in a
We have been using the versatile tris(pyrazolyl)borate
[1] and tris(pyrazolyl)methane ligands to prepare mono-
meric complexes of cadmium(II) and lead(II) in which
the coordination sphere about the metal can be con-
trolled by choice of substituent on the pyrazolyl rings of
the ligands [2]. We wish to compare complexes of the
two metals that have the same ligand set to determine
the stereochemical impact of the lone pair of electrons
on lead(II), a lone pair not present on cadmium(II) [3].
variety of different fashions [4ꢃ7]. In most cases the
/
cadmium(II) and lead(II) complexes are neutral contain-
ing two thiocyanate ligands with at least one of them
bridging two metals [8ꢃ11].
/
Reported here are the synthesis and structural char-
acterization of monothiocyanate complexes of these two
metals supported by the bulky anionic [HB(3-Butpz)3]ꢁ
(pzꢀpyrazolyl ring) and neutral 2,6-pyridyl-diimine
/
(pydim) ligands shown in Scheme 1.
Ligands bearing bulky substituents were chosen in an
attempt to prepare low coordination number complexes
* Corresponding author. Tel.: ꢂ
9521
E-mail address: reger@psc.sc.edu (D.L. Reger).
/
1-803-777-5263; fax: ꢂ1-803-777-
/
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 1 0 5 8 - 6

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D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ1807
/
2.2. {[HB(3-Butpz)3]Cd(II)}[BF4]
[Cd2(thf)5][BF4]4 (0.43 g, 0.50 mmol) and Tl[(HB(3-
Butpz)3] (0.58 g, 1.0 mmol) were dissolved in thf (20 ml)
and allowed to stir for 2 h at ambient temperature. The
mixture was filtered and the filtrate was evaporated to
leave a white solid (0.25 g, 0.43 mmol, 43%); m.p.ꢀ
/
98ꢃ
/
1
103 8C. H NMR (acetone-d6) d: 7.68, 6.11 (d, d; 3, 3;
Jꢀ
2.2 Hz; 4,5-H pz); 1.38 (27, s, But). FABꢂ MS: m/z
/
Calc. for {[HB(3-Butpz)3]113Cd}ꢂ: 495.1966. Found:
495.1980.
2.3. [HB(3-Butpz)3]Cd(NCS) (1)
Scheme 1.
[Cd2(thf)5](BF4)4 (0.43 g, 0.50 mmol) and Tl[HB(3-
Butpz)3] (0.58 g, 1.0 mmol) were charged into a round
bottom Schlenk flask and thf (35 ml) was added to the
flask via syringe. A white precipitate immediately
formed, the mixture was allowed to stir for 2 h at
room temperature (r.t.) and then filtered. The volatiles
were removed in vacuo leaving a white solid. This solid
and KSCN (0.080 g, 1.0 mmol) were dissolved in thf (20
ml). Immediately, a white precipitate formed, this
mixture was allowed to stir for 3 h at r.t. then filtered.
The solvent was removed in vacuo to leave a white solid
with terminal thiocyanate ligands. The planar bonding
substituted pyridine ligand pydim was chosen to con-
trast the tripodal, facial coordination of pyrazolylborate
ligands [12]. We also report the syntheses of two lead
thiocyanate complexes of less bulky tris(pyrazolyl)bo-
rate ligands. Specifically, the syntheses and solid state
structure determinations of the following will be dis-
cussed: [HB(3-Butpz)3]Cd(NCS), [(ButHpz)2Cd(m-NCS-
N,S)2]n, {[HB(3,5-Me2pz)3]Pb(m-NCS)}2, {[HB(pz)3]Pb-
(m-NCS)}n, [(pydim)Cd(m-NCS,N,S)]2[BF4]2, and [(py-
dim)Pb(NCS)][BF4]. In the two complexes that are
monomeric, the terminal thiocyanate ligands are N-
bound.
(0.10 g, 0.17 mmol, 17%); m.p.ꢀ
/
135ꢃ142 8C. X-ray
/
quality crystals were obtained from hot (508)/cold(08)
toluene. H NMR (acetone-d6) d: 7.78, 6.22 (3, 3; d, d;
1
Jꢀ
/
2.2 Hz; 4,5-H pz); 1.39 (27, s, But). IR (nCÅ
/
N,
Nujol mull, cmꢁ1): 2103. MS, direct ionization: m/z for
Mꢂ Calc. for {[HB(3-Butpz)3]113CdNCS}, 549.1732.
Found: 549.1739.
2. Experimental
2.1. General procedure
2.4. [(3-ButHpz)2Cd(m-NCS-S,N)2]n (2)
All operations were carried out under a nitrogen
atmosphere using standard Schlenk techniques and a
Vacuum Atmospheres HE-493 dry box. All solvents
X-ray quality crystals were obtained from an at-
tempted crystallization, from a layered solution of
acetone and hexane, of the product produced in the
[HB(3-Butpz)3]Cd(NCS) preparation. 1H NMR (ace-
tone-d6), d: 7.51 (2, br, 5-H pz); 6.09 (2, br, 4-H pz); 1.35
(18, s, But).
1
were dried, degassed, and distilled prior to use. The H
NMR spectra were recorded on a Varian AM300 or
AM400 spectrometer using a broad-band probe. Proton
chemical shifts are reported in ppm versus internal
Me4Si. Mass spectral data were recorded on a VG
70SQ mass spectrometer. Clusters assigned to specific
ions show appropriate isotopic patterns as calculated for
the atoms present. Infrared spectra were recorded on a
2.5. {[HB(3,5-Me2pz)3]Pb(m-NCS)}2 (3)
PbCl2 (0.25 g, 0.90 mmol) was dissolved in H2O (15
ml) and added to a thf (15 ml) solution of K[HB(3,5-
Me2pz)3] (0.30 g, 0.90 mmol). The mixture was stirred
for 0.5 h at which time a white precipitate was formed.
The mixture was filtered to leave a white solid. KSCN
(0.050 g, 0.50 mmol) was added to the filtrate. This
solution was allowed to stir for 6 h at r.t. A white
precipitate formed and the mixture was filtered. The
solvent was removed in vacuo to leave a white solid,
PerkinꢃElmer 781 spectophotometer. Anhydrous CdCl2
/
and KSCN were purchased from Aldrich Chemicals.
The compounds 2,6-bis[(2,6-dimethylphenylimino)-
methyl] pyridine (pydim), 2,6-bis[1-(2,6-dimethylpheny-
liimno)ethyl]pyridine (pydimMe2) [14], K[HB(pz)3] [1c],
K[HB(3,5-Me2pz)3]
[1d],
Tl[HB(Butpz)3]
[1g],
[Cd2(thf)5][BF4]4 [2b] and [HB(pz)3]PbCl [3a] were pre-
pared according to published methods.
(0.16 g, 31%); m.p.ꢀ
/
296ꢃ301 8C (dec). X-ray quality
/
Note! Cadmium and lead compounds and their wastes
are extremely toxic and must be handled carefully!!
crystals were obtained from a layered solution of
1
CH2Cl2 and hexane. H NMR (CDCl3) d: 5.81 (s, 3,

D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ
/1807
1797
4-H pz); 2.44 (s, 9, CH3); 2.30 (s, 9, CH3). IR: (nCÅ
/
N,
CH3). IR (nCÅ
/
N, Nujol mull, cmꢁ1): 2040 br. FABꢂ
Nujol mull, cmꢁ1): 2060 and 2020. ESꢂ/MS: Calc. for
{[HB(3,5-Me2pz)3]207Pb}ꢂ, 505.1770. Found: 505.1776.
Calc. for C32H44B2N14Pb2S2: C, 34.17; H, 3.94. Found:
C, 33.85; H, 4.55%.
MS: Calc. for [(pydimMe2)207Pb]ꢂ 635.1725. Found:
635.1744.
2.9. X-ray crystal determination for 1, 2, 3, 4, 5 and 6
2.6. {[HB(pz)3]Pb(m-NCS)}n (4)
Crystal, data collection, and refinement parameters
are collected in Table 1. Colorless crystals of 1, 2, 3 and
4 and small yellow crystals of 5 and 6 were epoxied onto
the end of a thin glass fiber. X-ray intensity data were
measured using a Bruker SMART APEX CCD-based
[HB(pz)3]PbCl (0.13 g, 0.30 mmol) was dissolved in
thf (10 ml) and KSCN (0.030 g, 0.30 mmol) added to
this solution. A white precipitate formed as this mixture
was stirred for 6 h at r.t. and the solution was filtered.
The solvent was removed in vacuo to leave a white solid,
diffractometer system using Mo Ka radiation (lꢀ
/
˚
0.71073 A). All unit cells were initially determined based
(0.080 g, 57%); m.p.ꢀ
were obtained from a layered solution of CH2Cl2 and
1
hexane. H NMR (acetone-d6) d: 7.76, 7.53 (3, 3; s, br;
/
222ꢃ
/
225 8C. Suitable crystals
on reflections harvested from a set of three scans
measured in orthogonal wedges of reciprocal space.
Subsequently, a hemisphere of data was collected with a
scan width of 0.38 in v and an exposure time of 60 s per
frame. The first 50 frames were re-collected at the end of
data set to monitor crystal decay. The structures were
solved by a combination of direct methods and differ-
ence Fourier syntheses, and refined by full-matrix least-
squares against F2, using the SHELXTL software package.
The final unit cell constants are based upon the
refinement of the XYZ centroids. In all structures,
hydrogen atoms were placed in calculated positions
and refined using a riding model and an empirical
absorption correction based on the multiple measure-
ment of equivalent reflections was applied with the
3,5-H pz); 6.12 (3, s, 4-H pz) IR: (nCÅ
/
N, Nujol mull,
cmꢁ1): 2084, 2045, 2030, 2004. FABꢂ MS: m/z Calc.
for {[HB(pz)3]207Pb}ꢂ, 419.0805. Found: 419.0796.
2.7. [(pydim)Cd(m-NCS-S,N)]2[BF4]2 (5)
[Cd2(thf)5](BF4)4 (0.24 g, 0.25 mmol) and pydim (0.18
g, 0.50 mmol) were charged into a round bottom
Schlenk flask and thf (20 ml) was added via syringe.
The mixture was allowed to stir for 1 h at r.t. and the
solvent was removed to leave a yellow solid. This solid
(0.15 g) and KSCN (0.050 g, 0.50 mmol) were dissolved
in thf (20 ml) and allowed to stir for 3 h at r.t. This
mixture was filtered and the volatiles were removed in
program SADABS
.
Systematic absences in the data for 1 were consistent
with the space groups Pnma and Pna21. After several
unsuccessful initial trials in the centrosymmetric space
group Pnma, the non-centrosymmetric space group
Pna21 was chosen and confirmed by the successful
solution and refinement of the structure. Upon success-
ful solution in Pna21, a check for missing symmetry was
performed with the ADDSYM routine in PLATON, which
verified the space group choice with a refined absolute
vacuo to leave a yellow solid (0.18 g, 55%); m.p.ꢀ
/
260ꢃ
/
262 8C (dec). Crystals suitable for X-ray analysis were
grown from a layered solution of CH2Cl2 and hexane.
1H NMR (acetone-d6), d: 9.03 (2, s, H-imino); 8.81 (1,
m, 4-H py); 8.56 (2, d, Jꢀ7.8, 3,5-H py); 7.14 (6, m,
/
3,4,5-H ph); 2.26 (12, s, CH3). IR (nCÅ
/
N, Nujol mull,
cmꢁ1): 2110, 2079. FABꢂ MS: m/z Calc. for
[(pydim)113Cd]ꢂ 509.0674. Found: 509.0668.
structure (Flack) parameter of ꢁ0.003(19). All non-
/
2.8. [(pydimMe2)Pb(NCS)][BF4] (6)
hydrogen atoms were refined with anisotropic displace-
ment parameters including the toluene solvent molecule
present in the cell. Crystals of 2 were determined to
belong to the monoclinic crystal system. Systematic
absences in the diffraction data determined that the
space group was P21/n. Compound 3, {[HB(3,5-
Pb(acac)2 (0.10 g, 0.25 mmol) was suspended in thf
(10 ml). The mixture was treated with 54% HBF4×
/
Et2O
(0.10 ml, 0.50 mmol) and was allowed to stir for 30 min
followed by addition of a thf (10 ml) solution of the
pydimMe2 ligand (0.090 g, 0.25 mmol) by cannula
transfer. The yellow reaction mixture was heated to
70 8C for 1 h. A solution of KSCN (0.040 g, 0.41 mmol)
in thf (10 ml) was added to the reaction mixture and
allowed to stir for 12 h at r.t. The mixture was filtered
and the solvent evaporated to dryness providing a
Me2pz)3]Pb(m-NCS)}2×/1.5CH2Cl2, crystallizes in the
orthorhombic crystal system. Examination of the sys-
tematic absences in the data set indicated the space
groups Pnma or Pna21. A good solution and refinement
was obtained in the space group Pnma, revealing two
{[HB(3,5-Me2pz)3]Pb}ꢂ cations related by mirror sym-
metry, and bridged by 2 inequiv. SCNꢁ groups. One
SCNꢁ lies in the mirror plane; the second SCNꢁ is
roughly perpendicular to the intervening plane, with the
central carbon (C2) in the mirror plane. Due to the
incompatibility of the SCNꢁ anion with a horizontal
yellow powder (0.14 g, 0.18 mmol, 72%); m.p.ꢀ
/
224ꢃ
/
227 8C. Crystals suitable for X-ray analysis were grown
from a layered solution of CH2Cl2 and hexane. 1H
NMR (acetone-d6), d: 8.91 (3, br, 3,4,5-H py); 7.20 (6,
br, 3,4,5-H ph); 2.60 (6, s, (CH3-imino), 2.24 (12, s,

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D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ1807
/
Table 1
Crystallographic data for [HB(3-But pz)3]Cd(NCS)×C6H5CH3 (1), [(3-But Hpz)2Cd(m-NCS-N,S)2]n (2), {[HB(3,5-Me2pz)3]Pb(m-NCS)}2×1.5CH2Cl2
(3), {[HB(pz)3]Pb(m-NCS)}n (4), [(pydim)Cd(m-NCS-N,S)]2[BF4]2 (5), and [(pydimMe2)Pb(NCS)][BF4]×2CH2Cl2 (6)
1
2
3
4
5
6
Empirical
formula
C
29H42BCdN7S
C16H22CdN6S2
C33.50H47B2Cl3N14Pb2S2 C10H10BN7PbS
C48H46B2Cd2F8S2 C27H29BCl2F4N4PbS
Formula weight
(g molꢁ1
643.97
474.92
1252.32
478.31
1197.47
806.50
)
Temperature (K)
Crystal system
Space group
293(2)
orthorhombic
Pna21
19.684(3)
16.029(2)
10.3224(15)
90
298(2)
monoclinic
P21/n
293(2)
orthorhombic
Pnma
173(2)
monoclinic
P21/c
173(2)
monoclinic
P21/c
293(2)
triclinic
¯
P
/1/
˚
a (A)
6.0016(2)
10.2759(3)
17.4673(5)
90
13.971(3)
22.218(4)
14.969(3)
90
15.0687(9)
23.3079(14)
13.4082(8)
90
14.884(3)
11.465(2)
15.911(3)
90
13.177(4)
14.677(4)
18.478(6)
103.762(6)
95.980(6)
110.748(6)
3175.4(17)
4
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
90
90
92.2898(16)
90
90
90
116.0440(10)
90
107.843(4)
90
3
˚
3256.9(8)
4
1.313
1076.38(6)
2
1.45
4646.5(14)
4
1.790
4231.0(4)
12
2.253
2584.4(9)
2
1.539
Density (Mg mꢁ3
F(000)
)
1.687
1568
1336
480
2412
2664
8556
Crystal size (mm) 0.30ꢄ0.24ꢄ0.14 0.10ꢄ0.10ꢄ0.5 0.40ꢄ0.11ꢄ0.03
0.20ꢄ0.16ꢄ0.01 0.40ꢄ0.40ꢄ0.04 0.42ꢄ0.30ꢄ0.10
Final R indices
a
[I ꢀ2s(I)]
R1ꢀ0.0318,
R2ꢀ0.0654
R1ꢀ0.0549,
wR2ꢀ0.1200
R1ꢀ0.0340,
wR2ꢀ0.0677
R1ꢀ0.0507,
wR2ꢀ0.1206
R1ꢀ0.0549,
wR2ꢀ0.1200
R1ꢀ0.0408,
wR2ꢀ0.0927
a
R1ꢀSjjFojꢁjFcjj/SjFoj. wR2ꢀ{S[w(Fo2ꢁFc2)2]/S[w(Fo2)2]}1/2
.
wꢀ1/[s2(Fo2)ꢂ(aP)2ꢂbP], where P is [2Fc2ꢂmax(Fo2, 0)]/3.
mirror plane, this arrangement results in this perpendi-
cular SCNꢁ apparently half-occupying two orientations
system. Systematic absences in the diffraction data
determined that the space group was P21/c. Compound
¯
6 crystallizes in the triclinic space group P1: The
/
related through the mirror plane, with similar SÃ
/
C and
asymmetric unit consists of two [Pb(C25H27N3)]2ꢂ
cations, two SCNꢁ and two BF4ꢁ counterions, and
two CH2Cl2 molecules. Comparison of identical reflec-
tions measured at the beginning and at the end of the
data collection showed an average loss of intensity of
4.1%; a linear decay correction was applied.
All computations were made using SHELXTL NT 5.10
and SADABS software (G. Sheldrick, Bruker AXS,
Madison, WI).
CÃN distances. However, removing the mirror plane
/
relating the two halves of the molecule and refining the
structure in Pna21 yielded the same disorder, as well as
chemically unreasonable [HB(3,5-Me2pz)3]ꢁ ligand geo-
metry and large correlations between atoms related by
symmetry in Pnma. Further attempts to remove the
disorder by reducing the symmetry even further to
monoclinic or triclinic symmetry gave identical results.
Therefore, Pnma was selected as the correct space
group. The similar S2Ã
/
C2 and C2Ã/N2 distances within
the perpendicular SCNꢁ are an artifact of the disorder.
While the displacement ellipsoid of C2 shows elongation
along the bond directions, no satisfactory model with
C2 off the mirror plane could be found. A total of 1.5
methylene chloride molecules disordered over three
positions were located and refined with the aid of three
geometrical restraints. Compound 4 crystallizes in the
space group P21/c as determined from the systematic
absences in the intensity data. The asymmetric unit
3. Results and discussion
3.1. tris(pyrazolyl)borate chemistry
The direct reaction of CdCl2 with 1 equiv. of Tl[HB(3-
Butpz)3] and KSCN did not produce the desired [HB(3-
Butpz)3]Cd(NCS) (1) complex. The complex was pro-
duced in a two step procedure, starting with the reactive
compound [Cd2(thf)5](BF4)4 [2b]. Mixing this com-
pound with two equiv. of Tl[HB(3-Butpz)3] produces
the intermediate {[HB(3-Butpz)3]Cd}[BF4].
contains
three
crystallographically
inequivalent
{[HB(pz)3]Pb}ꢂ cations and three SCNꢁ counterions
and all atoms are on general positions. Crystals of 5
were determined to belong to the monoclinic crystal

D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ
/1807
1799
This intermediate reacts with potassium thiocyanate
to yield [HB(3-Butpz)3]Cd(NCS) (1).
and selected bond angles and distances are shown in
Table 2. The cadmium(II) site has a N4 coordination
Complex 1 is air stable and is soluble in most common
solvents. Infrared analysis shows a strong band at 2103
cmꢁ1, indicating the presence of a N-bound, terminal
isothiocyante ligand. Reported CN stretching frequen-
cies for terminal cadmium(II) isothiocyanate are in the
arrangement in a pseudotetrahedral geometry. The
chelate rings restrict the intraligand NÃ
to an average of 88.68, with interligand NÃ
angles averaging 126.28. The CdÃNÃC bond angle of
the isothiocyanate ligand is significantly bent at
150.7(3)8 and the NÃCÃS bond angle is nearly linear
at 178.9(4)8. The CdÃNCS bond distance is 2.107(3) A,
on the short end of the published ranges of analogous
/
CdÃ
/
N angles
/
CdÃ
/N bond
/
/
range of 2059ꢃ
2108 cmꢁ1 [4b,5].
This arrangement was confirmed by a single crystal
X-ray analysis. An ORTEP drawing is shown in Fig. 1
/
/
/
˚
/

1800
D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ1807
/
Fig. 2. ORTEP diagram of [(3-But Hpz)Cd(m-NCS-N,S)]n (50% ellip-
soids).
Fig. 1. ORTEP diagram of [HB(3-But pz)3]Cd(NCS) (50% ellipsoids).
Table 3
t
Table 2
˚
Selected bond distances (A) and bond angles (8) for [(3-Bu Hpz)Cd(m-
NCS-N,S)]n (2)
˚
Selected bond distances (A) and bond angles (8) for [HB(3-
But pz)3]Cd(NCS) (1)
Bond distances
Bond distances
Cd(1)ÃN(1)
Cd(1)ÃN(3)
Cd(1)ÃS(1A)
2.286(9)
N(3)ÃC(8)
1.131(13)
1.650(13)
CdÃN(1)
2.107(3)
2.2234(19) N(31)ÃN(32)
2.219(2)
N(1)ÃC(1)
2.2302(18) C(1)ÃS
1.364(3)
N(21)ÃN(22)
1.360(3)
1.364(4)
1.093(4)
1.612(4)
2.309(10) C(8)ÃS(1)
2.762(2)
CdÃN(11)
CdÃN(21)
CdÃN(31)
N(11)ÃN(12)
Bond angles
N(1)ÃCd(1)ÃN(1C)
N(1)ÃCd(1)ÃS(1A)
N(1)ÃCd(1)ÃS(1B)
N(3)ÃCd(1)ÃN(1)
N(3)ÃCd(1)ÃN(1C)
N(3)ÃCd(1)Ã(S1A)
180.0(4)
92.4(2)
87.5(2)
88.5(4)
91.5(4)
91.5(4)
N(3)ÃCd(1)ÃS(1B)
88.4(2)
180.0(4)
180.0(9)
132.1(8)
101.6(3)
177.5(9)
N(3)ÃCd(1)ÃN(3C)
S(1A)ÃCd(1)ÃS(1B)
Cd(1)ÃN(1)ÃC(3)
Cd(1)ÃS(1)ÃC(8)
N(3)ÃC(8)ÃS(1)
Bond angles
N(1)ÃCdÃN(11)
N(1)ÃCdÃN(21)
N(1)ÃCdÃN(31)
N(11)ÃCdÃN(31)
128.87(12) N(11)ÃCdÃN(21)
126.57(11) N(21)ÃCdÃN(31)
123.22(13) C(1)ÃN(1)ÃCd
87.82(11)
90.10(12)
150.7(3)
87.97(7)
N(1)ÃC(1)ÃS
178.9(4)
in equatorial positions forming a CdN4S2 octahedral
arrangement. The cadmium(II) is located on an inver-
distances for terminal CdNCS groups [4,5,13]. The CdÃ
/
N bond distances for the [HB(3-Butpz)3]ꢁ ligand are all
sion center. The two pyrazole groups coordinate to
˚
N bond distance of 2.286(9) A,
˚
very similar and average 2.22 A.
cadmium with a CdÃ
/
As expected, the sterically demanding 3-tert-butyl
groups enforce the formation of a tetrahedral, mono-
meric complex, the first 4-coordinate cadmium(II)-
thiocyanate complex to be structurally characterized.
In contrast, many cadmium(II)-thiocyanate complexes
form intricate networks with bridging thiocyante ligands
coordinated to cadmium forming polymeric chains, 2-D
while the N-coordinated SCNꢁ groups have a CdÃ
/
N
˚
˚
distance 0.02 A longer at 2.309(10) A. The CdÃ
/
S
ꢁ
˚
distance is normal at 2.762(2) A. The SCN groups
are nearly linear at 177.5(9)8. The atoms of the doubly
bridging (m-NCS-N,S)ꢁ groups and the two cadmiu-
m(II) form an eight member ring that closely resembles
that observed in [Cd(NCS)2(CH3C5H4N)2]n [17],
Cd(NCS)2{(C6H5CH2)2NH}2 [18], and [Cd(NCS)2(iso-
nicotinamide)2] [19].
sheets and 3-D extended lattices [4,7,14ꢃ16].
/
In our first attempt to crystallize compound 1 from a
layered solution of acetone and hexane, the compound
we obtained was a decomposition product that was
shown by X-ray crystallography to be a polymer, [(3-
ButHpz)2Cd(m-NCS)2]n (2). Fig. 2 shows the ORTEP
diagram and bond distances and angles are shown in
Table 3. The cadmium(II) is six-coordinate, bonding to
two tert-butyl pyrazole rings located in the axial
positions and four doubly bridging thiocyanate ligands
Multiple attempts were made to synthesize the tetra-
hedral lead(II) compound analogous to 1 with the bulky
[HB(3-Butpz)3]ꢁ ligand, but this complex could not be
prepared. The tetrahedral enforcer character of this
ligand apparently prevents the formation of a four-
coordinate lead(II) complex with a stereochemically
active lone pair. The failure to prepare the lead(II)
analog of 1 clearly shows the influence of the lone pair.

D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ
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1801
Table 4
˚
Selected bond distances (A) and bond angles (8) for {[HB(3,5-
Me2pz)3]Pb(m-NCS)}2 (3)
Bond distances
PbÃS(1)
3.3277(16)
2.540(14)
2.386(4)
2.436(5)
2.381(5)
4.2361(9)
PbAÃS(2)
S(1)ÃC(1)
S(2)ÃC(2)
C(1)ÃN(1)
C(2)ÃN(2)
3.326(5)
1.673(11)
1.394(5)
1.079(11)
1.378(15)
PbÃN(2)
PbÃN(11)
PbÃN(21)
PbÃN(31)
Pbꢀ ꢀ ꢀPb(A)
Bond angles
N(11)ÃPbÃN(2)
N(21)ÃPbÃN(2)
N(31)ÃPbÃN(2)
N(11)ÃPbÃN(21)
N(11)ÃPbÃN(31)
N(21)ÃPbÃN(31)
N(11)ÃPbÃS(1)
N(21)ÃPbÃS(1)
N(31)ÃPbÃS(1)
89.2(4)
162.5(4)
89.6(4)
N(2)ÃPbÃS(1)
C(2)ÃN(2)ÃPb
C(1)ÃS(1)ÃPb
C(1)ÃS(1)ÃPb(A)
C(2)ÃS(2)ÃPb(A)
PbÃS(1)ÃPb(A)
S(2)ÃPb(A)ÃS(1)
N(1)ÃC(1)ÃS(1)
N(2)ÃC(2)ÃS(2)
105.2(3)
124.2(10)
121.3(2)
121.3(2)
85.5(4)
76.30(15)
77.79(14)
78.08(15)
161.79(11)
87.50(11)
90.93(10)
79.06(5)
109.98(9)
180.0(9)
176.9(11)
bridges them through sulfur with relatively long PbÃ
/
S
˚
bond distance of 3.3277(16) A [4c,11,20]. The other is in
a normal bridging m-NCS-S,N bonding one metal
through nitrogen and the other through sulfur, but
due to the incompatibility of this orientation of the
SCNꢁ anion with a horizontal mirror plane, this
perpendicular SCNꢁ half-occupies two orientations
Fig. 3. ORTEP diagram of {[HB(3,5-Me2pz)3]Pb(m-NCS)}2 (50% ellip-
soids).
In contrast, two new lead(II) compounds with less
sterically hindered ligands were prepared. The reaction
of equimolar amounts of PbCl2, K[HB(3,5-Me2pz)3] and
KSCN in thf yields {[HB(3,5-Me2pz)3]Pb(m-NCS)}2 (3).
related through the mirror plane. The CdÃ
distances for the [HB(3,5-Me2pz)3]ꢁ ligand are all
similar with a range of 2.381(5)ꢃ2.436(5) (average 2.40
/
N bond
/
˚
This compound is air-stable and soluble in halocar-
bons, thf, and slightly soluble in aromatic solvents. It
has CN stretching frequencies at 2060 and 2020 cmꢁ1
indicating bridging SCNꢁ groups.
A). Overall, the structure about each lead(II) can be
considered octahedral with three sites occupied by
nitrogen donor atoms from the [HB(3,5-Me2pz)3]ꢁ
ligand with NÃ
/
PbÃ/N bond angles restricted by the
Fig. 3 shows the ORTEP diagram of the cation in 3 and
selected bond distances and angles are shown in Table 4.
The solid state structure of 3 is dimeric with an unusual
structure containing both m-NCS-S,N and m-NCS-S,S
bridging SCNꢁ ligands. The m-NCS-S,S ligand is in the
mirror plane located between the two metal centers and
chelate rings to an average of 77.48. The sulfur of the
symmetrically bridged SCNꢁ occupies a fourth site
while the N and S from the disordered SCNꢁ share the
fifth site.
The remaining octahedral site is generally attributed
to a stereoactive lone pair on the lead(II) center. In

1802
D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ1807
/
Table 5
˚
Selected bond distances (A) and bond angles (8) for [HB(pz)3]Pb(m-
NCS)]n (4)
Bond distances
Pb(1)ÃN(111)
Pb(1)ÃN(121)
Pb(1)ÃN(131)
Pb(1)ÃN(1)
2.486(10) Pb(3)ÃN(331)
2.494(11) Pb(3)ÃN(311)
2.524(10) Pb(3)ÃN(321)
2.793(13) Pb(3)ÃN(3)
2.798(13) Pb(3)ÃS(3A)
2.410(11)
2.421(11)
2.455(10)
2.802(12)
3.251(4)
Pb(1)ÃN(2)
Pb(1)ÃS(1)A
Pb(2)ÃN(211)
Pb(2)ÃN(221)
Pb(2)ÃN(231)
Pb(2)ÃS(1)
3.134(4)
2.508(10) S(1)ÃC(1)
2.448(9)
C(2)ÃN(2)
C(1)ÃN(1)
1.178(18)
1.588(16)
1.108(16)
1.650(16)
1.137(15)
2.460(10) S(2)ÃC(2)
3.015(4)
1.644(13)
C(3)ÃN(3)
S(3)ÃC(3)
Bond angles
N(111)ÃPb(1)ÃN(121) 73.0(3)
N(111)ÃPb(1)ÃN(131) 78.6(3)
N(121)ÃPb(1)ÃN(131) 74.7(3)
N(211)ÃPb(2)ÃN(221) 78.8(3)
N(211)ÃPb(2)ÃN(231) 75.9(3)
N(221)ÃPb(2)ÃN(231) 74.8(3)
N(111)ÃPb(1)ÃN(1)
N(121)ÃPb(1)ÃN(1)
N(131)ÃPb(1)ÃN(1)
N(111)ÃPb(1)ÃN(2)
N(121)ÃPb(1)ÃN(2)
N(131)ÃPb(1)ÃN(2)
84.1(4)
145.2(4)
126.6(4)
97.5(3)
N(211)ÃPb(2)ÃS(1)
N(221)ÃPb(2)ÃS(1)
N(231)ÃPb(2)ÃS(1)
157.6(2)
97.2(2)
81.8(3)
N(311)ÃPb(3)ÃN(321) 75.3(3)
N(311)ÃPb(3)ÃN(331) 77.6(4)
N(321)ÃPb(3)ÃN(331) 78.5(3)
78.5(3)
152.9(3)
Fig. 5. {[HB(pz)3]Pb(3)(m-NCS-N,S)}2 units in {[HB(pz)3]Pb(m-
NCS)}n .
N(111)ÃPb(1)ÃS(1A) 160.4(3)
N(311)ÃPb(3)ÃS(3A)
88.9(2)
N(121)ÃPb(1)ÃS(1A)
N(131)ÃPb(1)ÃS(1A)
N(1)ÃPb(1)ÃS(1A)
N(2)ÃPb(1)ÃS(1A)
94.9(3)
83.3(2)
113.3(3)
95.1(2)
N(321)ÃPb(3)ÃS(3A) 162.0(2)
N(331)ÃPb(3)ÃS(3A)
N(311)ÃPb(3)ÃN(3)
N(321)ÃPb(3)ÃN(3)
90.0(3)
87.6(3)
94.2(3)
164.6(4)
˚
distorted structure of [HB(pz)3]2Pb are 0.24 A longer, on
average, than the trans PbÃN bonds [3a]. In addition,
the nitrogen atom of the SCNꢁ ligand in the mirror
/
Pb(1)ÃS(1A)ÃPb(2A) 152.24(14) N(331)ÃPb(3)ÃN(3)
˚
plane has long range interactions at 3.161(5) A with
both lead(II) centers of an adjacent dimeric unit in the
area of this open, sixth site, an unlikely interaction if
substantial electron density from the lone pair on
lead(II) were present. These results support calculations
that indicate that in distorted structures of lead(II) the
amount of mixing of the p orbital into the lone pair
orbital is small [3g].
general, it is well known that in higher coordinate lead
structures, bonds adjacent to the presumed location of
the lead(II) lone pair are longer than bonds remote from
the lone pair [21]. The structure of 3 is very unique in
that the PbÃ
/
N bonds of the [HB(3,5-Me2pz)3]ꢁ ligand
˚
adjacent to the open site are only 0.03 A longer, on
The reaction of [HB(pz)3]PbCl and KSCN in equi-
molar amounts in thf yields {[HB(pz)3]Pb(m-NCS)}n (4).
average, than the trans PbÃ
/
N bond. For comparison,
the three PbÃN bonds adjacent to the open site in the
/
Fig. 4. Diagram of the polymer chain formed by Pb(1) and Pb(2) in {[HB(pz)3]Pb(m-NCS)}n .

D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ
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1803
rings, Fig. 5, with the two lead units on each side of
the sandwich array.
Shown in Fig. 6 is a combined view perpendicular to
the view in Figs. 4 and 5. The {[HB(pz)3]Pb(3)(NCS)}2
units are surrounded by two of the infinite chains
formed by Pb(1) and Pb(2). There are secondary
interactions between the two units, most notably
between the bridging N(3) of the dimeric Pb(3) units
˚
and Pb(2) at 2.996 A. There are also pꢃp stacking
/
interactions between the pyrazolyl groups attached to
Pb(1) along the chain and between alternate Pb(2) and
Pb(3) pyrazolyl groups attached parallel to this chain
˚
ranging from 3.50 to 3.69 A. Typical interplanar
distances for pꢃp interactions of aromatic groups range
/
˚
from 3.3 to 3.8 A [22].
Fig. 6. Total arrangement of the three types of lead(II) in
{[HB(pz)3]Pb(m-NCS)}n viewed perpendicular to the view in Figs. 4
and 5. Hydrogen atoms have been omitted for clarity.
3.2. 2,6-bis(imino)pyridine chemistry
Using a method similar to the preparation of the
This compound is air-stable and soluble in halocar-
bons, thf, and slightly soluble in some aromatic solvents.
It has CN stretching frequencies at 2084, 2045, 2030,
2004 cmꢁ1 indicating a complicated bridging arrange-
ment of the SCNꢁ groups.
tris(pyrazolyl)borate compound 1, a new thiocyanate
complex of the pydim ligand is prepared starting with
The solid state structure was solved crystallgraphi-
cally and selected bond distances and angles are shown
in Table 5. The structure of this complex is a compli-
cated infinite 2-D layered array in which
{[HB(pz)3]Pb}ꢂ groups sandwich a layer of SCNꢁ
ligands with the lead(II) centers oriented toward them.
There are three independent {[HB(pz)3]Pb(NCS)}ꢂ
units. As shown in the lower part of Fig. 4,
{[HB(pz)3]Pb(1)}ꢂ units form a chain connected by
(m-SCN-S,N)ꢁ ligands. There is also a terminal N-
bound SCNꢁ making Pb(1) six-coordinate. The brid-
ging SCNꢁ groups are also linked through sulfur to the
{[HB(pz)3]Pb(2)}ꢂ units on the other side of the
sandwich array. The {[HB(pz)3]Pb(3)}ꢂ units are in a
centrosymmetric dimeric arrangement with end-on brid-
ging (m-SCN-N,S)ꢁ ligands forming eight member
Fig. 7. ORTEP diagram of [(pydim)Cd(m-NCS-N,S)]2[BF4]2 (50%
ellipsoids)

1804
D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ1807
/
Table 6
˚
Selected bond distances (A) and bond angles (8) for [(pydim)Cd(m-
NCS-N,S)]2[BF4]2 (5)
Bond distances
Cd(1)ÃN(1)
Cd(1)ÃN(2)
Cd(1)ÃN(3)
Cd(1)ÃN(4)
2.246(6)
2.256(5)
2.452(5)
2.448(5)
N(1)ÃC(1)
C(1)ÃS(1)
Cd(1)ÃF(1)
Cd(1)ÃS(1)
1.155(8)
1.667(7)
2.544(4)
2.5551(17)
Bond angles
N(1)ÃCd(1)ÃN(2)
N(1)ÃCd(1)ÃN(3)
N(1)ÃCd(1)ÃN(4)
N(2)ÃCd(1)ÃN(3)
N(2)ÃCd(1)ÃN(4)
N(3)ÃCdÃN(4)
N(1)ÃCd(1)ÃS(1)
N(2)ÃCd(1)ÃS(1)
N(3)ÃCd(1)ÃS(1)
108.92(19) N(4)ÃCd(1)ÃS(1)
100.4(2)
S(1)ÃCd(1)ÃF(1)
94.51(19) N(1)ÃCd(1)ÃF(1)
69.6(17)
N(2)ÃCd(1)ÃF(1)
70.63(17) N(3)ÃCd(1)ÃF(1)
140.15(16) N(4)ÃCd(1)ÃF(1)
123.55(12)
78.0(9)
171.71(18)
77.07(15)
86.95(15)
81.94(15)
178.9(6)
99.2(2)
98.0(15)
N(1)ÃC(1)ÃS(1)
148.87(13) Cd(1)ÃS(1)ÃC(1)
90.78(13) Cd(1)ÃN(1)ÃC(1)
156.35(5)
Fig. 8. ORTEP diagram of [(pydimMe2)Pb(1)(NCS)][BF4] (50% ellip-
soids).
[Cd2(thf)5][BF4]4. This starting material is treated first
with the pydim ligand followed by potassium thiocya-
nate resulting in the formation of [(pydim)Cd(m-NCS-
S,N)]2[BF4]2 (5).
making the overall structure a dimer. The three nitrogen
atoms of the planar pyridine ligand occupy three sites in
a meridional arrangement, but the intrinsic bite angle of
This complex is air-stable in the solution and solid
states. It is soluble in acetone, CH2Cl2, and chloroform.
The infrared spectrum shows CN stretching frequencies
of 2078 and 2110 cmꢁ1, indicating that the SCNꢁ
ligands are in bridging positions [5,11].
X-ray crystallography shows that the complex is a
dimer. Fig. 7 shows an ORTEP drawing of 5, and selected
bond distances and angles are shown in Table 6. The
environment about the cadmium(II) is best described as
a distorted octahedron. It is strongly bonded by five
donor atoms, with the two bridging thiocyanate groups
the ligand coupled with the large size of the cadmium(II)
force a significant distortion from an octahedral ar-
rangement with the trans NÃ
140.15(16)8. The CdÃN(py) bond (2.256(5) A) is sig-
nificantly shorter than the CdÃN(imino) bonds (average
/
CdÃ
/
N bond angle of
˚
/
/
ꢁ
˚
2.45 A). The bridging SCN groups form a NÃ
angle much greater than 908 at 123.55(12)8 and the
SCNꢁ ligands are nearly linear at 178.9(6)8. The CdÃ
/
CdÃ
/
S
/
˚
NCS bond distance is 2.246(6) A and the CdÃ
distance is 2.5551(17) A, both typical for this bridging
ligand forming an eight membered ring with the two
/
SCN bond
˚

D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ
/1807
1805
cadmium(II) [10,14ꢃ
N(1)ÃC(1) bond angle of 156.35(5)8 is much larger
than the Cd(1)Ã C(1) bond angle of 99.2(2)8. The
/
16]. Within the ring, the Cd(1)Ã
/
angles are nearly linear. In contrast to the cadmium
complex 5 and other structures of the pydim ligand
/
˚
/
S(1)Ã
/
[12b], the CdÃ
/
N(py) bond (2.466 (6) A) for Pb(1) is
N(imino) bond
distances (2.456(6) A) and only slightly shorter than the
sixth coordination site is occupied by a weak interaction
actually longer than one of the CdÃ
/
ꢁ
˚
from a fluorine of the BF4 group.
˚
An analogous lead(II) isothiocyanide complex was
synthesized using similar chemistry as outlined in the
cadmium synthesis using the pydimMe2 ligand. In this
reaction, Pb(acac)2 was treated with two equiv. of
tetrafluorohydroboric acid followed by one equiv. of
pydimMe2 and KSCN to yield a tetra-coordinate
lead(II) complex [(pydimMe2)Pb(NCS)][BF4] (6).
other (2.522(6) A). While the CdÃ
/
N(py) bond distance
(2.466(5) A) for Pb(2) is shorter than the average of the
˚
˚
N(imino) bond distances (2.54 A), the difference is
CdÃ
/
˚
much less than the 0.2 A distance commonly observed
[12]. As expected for the larger size of lead(II) compared
with cadmium(II), the three nitrogen atoms of the
planar pyridine ligand form even smaller NÃ
/
PbÃ/N
This moderately high melting solid compound is air-
stable and soluble in halocarbons and acetone. The CN
stretching frequency is a broad band centered at 2040
bond angles with the trans N(11)Ã
/
Pb(1)Ã
/
N(13) bond
angles of only 129.1(2)8 for Pb1 and 129.6(2)8 for Pb(2).
cmꢁ1
.
The solid state structure was determined by X-ray
crystallography. There are two independent cations in
the structure, Fig. 8 shows an ORTEP drawing for one of
those, Pb(1), and Table 7 shows the bond angles and
distances for both. The primary structures of both
cations are similar and are four-coordinate monomeric
arrangements. The geometry about lead(II) is irregular,
with the N-bound SCNꢁ ligand oriented basically
perpendicular to the N3Pb plane formed by the donor
atoms of the pydimMe2 ligand and lead(II). The planes
of the phenyl rings are also oriented essentially ortho-
4. Conclusions
We have prepared and characterized several cadmiu-
m(II) and lead(II) thiocyanate complexes containing
either tris(pyrazolyl)borate ligands or neutral 2,6-pyr-
idyl-diimine ligands and one thiocyanate ligand per
metal. Complex 1, [HB(3-Butpz)3]Cd(NCS), is the first
4-coordinate cadmium(II) isothiocyanate complex to be
structurally characterized and contains a short CdÃ
/NCS
˚
bond distance (2.107(3) A). An analogous complex of
lead(II) could not be synthesized. It appears that the
tetrahedral enforcer character of this ligand prevents the
formation of a four-coordinate lead(II) complex with a
stereochemically active lone pair and, apparently, a
tetrahedral complex isostructural with 1 is energetically
unfavorable. The use of less sterically demanding
tris(pyrazolyl)borate ligands allowed the preparation
gonal to this plane. The PbÃ/NCS bond distances are
short, as would be expected for the low coordinate
˚
number for lead(II) of four, at 2.275(7) A for Pb(1) and
˚
2.333(7) A for Pb(2). Published PbÃ
/
NCS bond distances
NÃC bond angles
are 152.6(7)8 and 156.0(7)8 while the NÃCÃS bond
˚
range from 2.4 to 2.8 A [11]. The PbÃ
/
/
/
/

1806
D.L. Reger et al. / Polyhedron 21 (2002) 1795ꢃ1807
/
Table 7
is very different from 5, presumably because of the
stereoactive lone pair on lead(II).
˚
Selected bond distances (A) and bond angles (8) for [(pydim-
Me2)Pb(NCS)][BF4] (6)
Bond distances (molecule 1)
Pb(1)ÃN(1)
Pb(1)ÃN(11)
Pb(1)ÃN(12)
Pb(1)ÃN(13)
N(1)ÃC(1)
2.275(7)
2.456(6)
2.466(6)
2.522(6)
1.110(9)
1.455(13)
N(11)ÃC(19)
N(12)ÃC(21)
N(12)ÃC(25)
N(13)ÃC(26)
N(13)ÃC(28)
C(1)ÃS(1)
1.269(11)
1.342(9)
1.330(9)
1.275(8)
1.436(9)
1.623(9)
5. Supplementary material
Crystallographic data for the structures reported in
this paper have been deposited at the Cambridge
Crystallographic Data Center, CCDC 177361ꢃ177366.
/
N(11)ÃC(11)
Copies of the information may be obtained free of
charge from the Director, CCDC, 12 Union Road,
Bond angles
N(1)ÃPb(1)ÃN(11)
N(1)ÃPb(1)ÃN(12)
N(1)ÃPb(1)ÃN(13)
N(11)ÃPb(1)ÃN(12)
N(11)ÃPb(1)ÃN(13) 129.1(2)
N(12)ÃPb(1)ÃN(13)
C(28)ÃN(13)ÃPb(1)
83.9(2)
86.0(2)
86.2(2)
64.7(2)
C(1)ÃN(1)ÃPb(1)
152.6(7)
116.7(6)
119.5(6)
119.5(6)
119.8(4)
120.0(5)
176.4(9)
C(11)ÃN(11)ÃPb(1)
C(19)ÃN(11)ÃPb(1)
C(21)ÃN(12)ÃPb(1)
C(25)ÃN(12)ÃPb(1)
Cambridge, CB2 1EZ, UK (fax: ꢂ44-1223-336-033;
/
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
64.96(19) C(26)ÃN(13)ÃPb(1)
119.3(4)
N(1)ÃC(1)ÃS(1)
Acknowledgements
Bond distances (molecule 2)
Pb(2)ÃN(2)
Pb(2)ÃN(23)
C(2)ÃN(2)
C(41)ÃN(21)
C(51)ÃN(22)
C(56)ÃN(23)
2.333(7)
Pb(2)ÃN(22)
Pb(2)ÃN(21)
C(2)ÃS(2)
C(49)ÃN(21)
C(55)ÃN(22)
C(58)ÃN(23)
2.466(5)
2.577(6)
1.604(8)
1.266(9)
1.325(9)
1.430(10)
2.509(5)
1.150(9)
1.432(10)
1.345(9)
1.291(8)
The authors thank the National Institute of Health
(GM-26295 for D.L.R) and the National Science
Foundation (CHE-0110493 for D.L.R) for support.
The Bruker CCD Single Crystal Diffractometer (at the
University of South Carolina) was purchased using
funds provided by the NSF Instrumentation for Materi-
als Research Program through Grant DMR: 9975623.
The NSF (Grants CHE-8904942 and CHE-9601723)
and NIH (Grant RR-02425) have supplied funds to
support NMR equipment and the NIH (Grant RR-
02849) has supplied funds to support mass spectrometry
equipment at the University of South Carolina.
Bond angles
N(2)ÃPb(2)ÃN(21)
N(2)ÃPb(2)ÃN(22)
N(2)ÃPb(2)ÃN(23)
N(22)ÃPb(2)ÃN(21)
N(22)ÃPb(2)ÃN(23)
C(2)ÃN(2)ÃPb(2)
C(41)ÃN(21)ÃPb(2)
90.8(2)
91.2(2)
85.8(2)
64.0(2)
65.8(2)
156.0(7)
119.7(4)
C(49)ÃN(21)ÃPb(2)
C(51)ÃN(22)ÃPb(2)
C(55)ÃN(22)ÃPb(2)
C(56)ÃN(23)ÃPb(2)
C(58)ÃN(23)ÃPb(2)
N(23)ÃPb(2)ÃN(21) 129.6(2)
N(2)ÃC(2)ÃS(2) 178.0(7)
119.9(5)
119.5(6)
118.6(5)
118.7(5)
121.3(5)
of two interesting new [tris(pyrazolyl)borate]Pb(NCS)
complexes. The use of the 3,5-dimethyl substituted
ligand produces {[HB(3,5-Me2pz)3]Pb(m-NCS)}2 that
has a dimeric structure with both m-NCS-S,N and m-
NCS-S,S bridging SCNꢁ ligands. The parent ligand
produces {[HB(pz)3]Pb(m-NCS)}n, having an unusual
infinite 2-D layered array in which three nonequiv.
{[HB(pz)3}Pb}ꢂ groups sandwich a layer of SCNꢁ
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