New trisubstituted cyanopyrazoles and cyanoscorpionates

Article abstract of DOI:10.1016/j.poly.2016.12.016

New syntheses are reported to give pyrazoles with cyano substituents at the 4-position of the pyrazole ring and ethyl or isopropyl substituents at the 3-position, as well as pyrazoles with cyano substituents at the 4-position and alkyl/aryl/bromo substituents at both the 3- and 5-positions. Synthesis of scorpionates using tetradecane as a high-boiling solvent has been shown to be more efficient than the melt method and has led to new scorpionates using the newly synthesized pyrazoles. An unexpected complex is isolated in which the Ni(cyclam)²⁺moiety crystallizes with two cyanoscorpionates as counterions, without binding of the scorpionate ligands to the Ni atom.

Full text of DOI:10.1016/j.poly.2016.12.016

Accepted Manuscript
New trisubstituted cyanopyrazoles and cyanoscorpionates
Lava R. Kadel, John R. Kromer, Curtis E. Moore, David M. Eichhorn
PII:
S0277-5387(16)30667-2
DOI:
http://dx.doi.org/10.1016/j.poly.2016.12.016
POLY 12374
Reference:
Polyhedron
To appear in:
Received Date:
Revised Date:
Accepted Date:
4 July 2016
9 December 2016
10 December 2016
Please cite this article as: L.R. Kadel, J.R. Kromer, C.E. Moore, D.M. Eichhorn, New trisubstituted cyanopyrazoles
and cyanoscorpionates, Polyhedron (2016), doi: http://dx.doi.org/10.1016/j.poly.2016.12.016
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New trisubstituted cyanopyrazoles and cyanoscorpionates
Lava R. Kadel1, John R. Kromer1, Curtis E. Moore2 and David M. Eichhorn1,*
1Department of Chemistry, Wichita State University, 1845 Fairmount, Wichita KS, 67260
2Department of Chemistry and Biochemistry, University of California - San Diego, 9500 Gilman Dr.,
La Jolla, CA 92093
david.eichhorn@wichita.edu

Abstract
New syntheses are reported to give pyrazoles with cyano substituents at the 4-position of the pyrazole
ring and ethyl or isopropyl substituents at the 3-position, as well as pyrazoles with cyano substituents at
the 4-position and alkyl/aryl/bromo substituents at both the 3- and 5- positions. Synthesis of
scorpionates using tetradecane as a high-boiling solvent has been shown to be more efficient than the
melt method and has led to new scorpionates using the newly synthesized pyrazoles. An unexpected
complex is isolated in which the Ni(cyclam)2+ moiety crystallizes with two cyanoscorpionates as
counterions, without binding of the scorpionate ligands to the Ni atom.
Keywords
Scorpionate ligands, pyrazoles, Ni complex, crystal structure

1. Introduction
Scorpionate ligands were introduced in the mid-1960’s with the report by Trofimenko of the parent
unsubstituted compounds dihydrobis(pyrazol-1-yl)borate (Bp) and hydrotris(pyrazol-1-yl)borate (Tp) and
complexes of these ligands with various divalent metal ions.[1] The versatility of the polypyrazolylborate
scaffold was soon recognized and the chemistry of what Trofimenko would later rename “scorpionate”
ligands [2] blossomed with the synthesis of second-generation scorpionates with substituents on the C
atoms of the pyrazole rings. It was demonstrated that substitution at the 3-position of the pyrazole ring
with increasingly bulky substituents could impart unique electronic properties and reactivity paradigms,
[3,4] while incorporation of electronically active substituents such as halogens [3,5-7] or CF3 [8-15] could
also affect the properties of the ligands and resulting metal complexes.
Cyanoscorpionate ligands (i.e., those bearing a CN substituent at the 4-position of the pyrazole rings)
were first reported by Trofimenko with the synthesis of Bp4CN and heteroleptic metal complexes of this
ligand. [16] Soon after, our group reported the homoleptic monomeric complexes of BpPh,4CN with Co(II)
and Cu(II), [17] and we have since reported further development of the chemistry of BpR,4CN and TpR,4CN
(R = Ph, t-Bu), including the formation of TpPh,4CN*2M complexes with (where the * indicates a ligand tht
has been isomerized via a borotropic shift to place one substituent in the 5-position), [18] Tpt-Bu,4CN2ML4
complexes with coordination of the Tp ligands only via the CN substituent, [19] and the one-dimensional
polymers (TpR,4CNCu)n. [20] In the course of these studies, it has become evident that these disubstituted
cyanoscorpionate ligands (i.e., with substitution at the 3-position of the pyrazole rings in addition to the
CN group at the 4-position) show some tendency toward ligand decomposition through loss of a
pyrazole from the TpR,4CN, resulting in the isolation of compounds such as TpPh,4CNBpPh,CNM and
M(HpzPh,4CN)4Cl2 from reactions containing pure TpPh,4CN. [21] In an attempt to develop cyanoscorpionates
which are more resistant to decomposition, we undertook to synthesize 4-cyanopyrazoles with
substituents at both the 3- and 5-positions. We report herein modified synthetic methods for
cyanopyrazoles, the synthesis of a number of new di- and tri-substituted cyanopyrazoles, and new
scorpionate ligands based on these cyanopyrazoles.
2. Experimental
General Experimental. All reagents were used as received from Sigma-Aldrich or ACROS (Fisher
Scientific). When anhydrous solvents are indicated they were obtained from an Innovative Technology
Pure Solv (Model # PS-MD-7) Solvent Purifier (THF, acetonitrile, methanol, dichloromethane) or distilled
from sodium benzophenone (toluene). Mass spectrometry was performed on a Varian 1200L
quadrupole MS or Agilent TOF 6230. Infrared spectra were recorded as neat solids on a Nicolet Avatar
360 FT-IR spectrometer with an ATR attachment. NMR spectra were taken on a Varian Inova 400 MHz
NMR spectrometer. Elemental Analyses were performed by MHW Laboratories, Phoenix, AZ.
X-ray Crystallography. A crystal was affixed to a nylon cryoloop using oil (Paratone-n, Exxon) and
mounted in the cold stream of a Bruker Kappa-Apex-II diffractometer. The temperature of the crystal
was maintained at 150 K using a Cryostream 700EX Cooler (Oxford Cryosystems). Data were measured
using a CCD detector at a distance of 50 mm from the crystal with a combination of phi and omega
scans. A scan width of 0.5° and scan time of 10 s were employed using graphite monochromated
molybdenum Kα radiation (λ = 0.71073 Å) that was collimated to a 0.6 mm diameter. Data collection and
reduction were performed using the Bruker Apex2 suite (v2013.4-1). [22] All available reflections to

2θmax = 52° were harvested and corrected for Lorentz and polarization factors with Bruker SAINT (v6.45).
[23] Reflections were then corrected for absorption, interframe scaling, and other systematic errors with
SADABS 2004/1.48. [24] The structures were solved (direct methods) using SHELX-T [25] and refined
(full-matrix least-squares against F2) with SHELX-L within the OLEX2 software suite. [26] All non-
hydrogen atoms were refined using anisotropic thermal parameters. All hydrogen atoms were included
at idealized positions; hydrogen atoms were not refined. It should be noted that a few of the structures
reported herein are not of the highest possible quality, due in large part to poorly diffracting crystals
(especially for 8). However, in all cases, the structures are unambiguous and sufficiently good enough to
support the conclusions.
3-oxo-3-phenylpropanenitrile (benzoylacetonitrile, 1a). In a slight modification of the procedure
reported by Badiger, et al., [27] sodium hydride (60%, 15.08 g, 377.0 mmol) in a round bottom flask was
cooled using an ice-water bath and kept under nitrogen atmosphere on a Schlenk line. Anhydrous
acetonitrile (19.0 mL, 360 mmol) and 10.0 mL of anhydrous DMSO were added to the flask and the
mixture was stirred for 20 minutes. Methyl benzoate (37.8 mL, 40.8 g, 300 mmol) was added to the
reaction mixture. After stirring for approximately 1.5 hours, the reaction mixture turned into a thick
white solid. The excess NaH in the reaction mixture was quenched by slow addition of deionized water.
HCl (62.3 mL 12.1 M, diluted to 600 mL) was added to fully protonate the product, which immediately
gave a milky white suspension. The product was then extracted three times (150 mL each) with ethyl
acetate. All organic layers were combined and washed with NaCl brine. The organic layer was dried over
anhydrous MgSO4 and filtered. Solvent was evaporated under reduced pressure, giving a light orange oil,
which, when triturated with a 1:1 mixture of hexane and diethyl ether, yielded 41.33 g (284.7 mmol,
95%) of 1a as a very light yellow solid. 1H NMR (CDCl3, δ downfield of TMS) 7.89 ppm (m, 2H), 7.65 ppm
(m, 1H), 7.51 ppm (m, 2H), 4.07 ppm (s, 2H). IR (cm-1): 2255 (νCN), 1686 (νCO).
3-phenyl-4-cyanopyrazole (HpzPh,4CN, 2a). To a solution of 3-oxo-3-phenylpropanenitrile (1a) (8.0129 g,
55.2 mmol) in anhydrous toluene (200 mL), was added DMF dimethylacetal (8.2 mL, 7.27 g, 61 mmol)
and the mixture was stirred overnight under nitrogen. The solvent was evaporated under reduced
pressure, to give a red-brown oil. Purification by flash chromatography with dichloromethane as the
mobile phase yields 2-benzoyl-3-dimethylaminoacrylonitrile as a light yellow solid (8.67 g, 43.3 mmol,
78.4 %). The 2-benzoyl-3-dimethylaminoacrylonitrile was dissolved in 100 mL of methanol, and
hydrazine hydrate (64%, 3.15 mL, 64.9 mmol) in 10 mL of methanol was added dropwise. After stirring
overnight, the solvent was evaporated under reduced pressure, and the product was purified by column
chromatography with 50:50 ethyl acetate:hexanes as the mobile phase. The first light yellow band
yielded 2a (6.40 g, 37.8 mmol, 87.4 %; overall yield from 3-oxo-3-phenylpropanenitrile 68.5 %). 1H NMR
(CDCl3, δ downfield of TMS) 7.26 ppm (s, 1H), 7.499 ppm (t, 2H), 7.85 ppm (t, 2H), 7.99 ppm (s, 1H), 11.5
ppm (N-H, broad, s). IR (cm-1): 2233 (vs, νCN). ESI-MS (m/z): 168.1 [pzPh,4CN]-, 337.1 [HpzPh,4CN] + [pzPh,4CN]-.
Elemental analysis was not obtained for this compound, as it has been previously reported.
3-t-butyl-4-cyanopyrazole (HpztBu,4CN, 2b). To a solution of pivaloylacetonitrile (4,4-dimethyl-3-
oxopentanenitrile) (8.0685 g, 64.5 mmol) in 200 mL of anhydrous toluene was added DMF
dimethylacetal (9.50 mL, 8.46 g, 71.0 mmol). The colorless pivaloylacetonitrile solution turned light
yellow immediately after the addition of DMF-DMA. The reaction mixture was stirred overnight under
nitrogen. The solvent was evaporated under reduced pressure producing a yellow liquid, which, upon
standing, solidified to give 2-tert-butyl-3-dimethylaminoacrylonitrile (11.63 g, 64.3 mmol, 100%) as a

light yellow solid. The 2-tert-butyl-3-dimethylaminoacrylonitrile was dissolved in 100 mL of methanol,
and hydrazine hydrate (64%, 4.70 mL, 96.9 mmol) in 10 mL of methanol was added dropwise. After
stirring overnight, the solvent was evaporated under reduced pressure to give a brown-red oily product.
The product was purified by column chromatography with 50:50 ethyl acetate:hexanes as mobile phase.
The first light yellow band yielded 9.03 g (60.5 mmol, 93.8%) of 2b. 1H NMR (CDCl3, δ downfield of TMS)
1.45 ppm (s, 9H), 7.82 ppm (s, 1H). IR (cm-1): 2227 (vs, νCN). ESI-MS (m/z): 148.2 [pzt-Bu,4CN]-, 297.2 [Hpzt-
Bu,4CN] + [pzt-Bu,4CN]-. Elemental analysis was not obtained for this compound, as it has been previously
reported.
3-ethyl-4-cyanopyrazole (HpzEt,4CN, 2d). Sodium hydride (60%, 11.50 g, 287 mmol) in a round bottom
flask was cooled using an ice-water bath and kept under nitrogen atmosphere on a Schlenk line.
Anhydrous acetonitrile (15.0 mL, 287 mmol) and 9.0 mL of anhydrous DMSO were added to the flask
and the mixture was stirred for 30 minutes. Methyl propionate (27.7 mL, 25.3 g, 287 mmol) was added
to the reaction mixture. After stirring for approximately 5 hours, the reaction mixture turned into a thick
white solid. An additional 20 mL of DMSO was added and the suspension was stirred overnight. The
excess NaH in the reaction mixture was quenched by slow addition of deionized water. NH4Cl (30.7 g)
was added to fully protonate the product, which immediately gave a milky white suspension. The
product was then extracted three times (150 mL each) with ethyl acetate. All organic layers were
combined and washed with NaCl brine, dried over anhydrous MgSO4, and filtered, and the solvent was
evaporated under reduced pressure. The product was purified by column chromatography using CHCl3
as the mobile phase, yielding 10.41 g (107 mmol, 37.3 % yield) of 3-oxo-pentanenitrile. This product was
dissolved in 100 mL of toluene, and 15.7 mL (13.2 g, 111 mmol) of dimethylformamide-dimethylacetal
(DMF-DMA) was added. The reaction was stirred for 18 hours, after which the solvent was removed
under reduced pressure and the product (2-((dimethylamino)methylene)-3-oxopentanenitrile) purified
by column chromatography using CHCl3 as the mobile phase. The solvent was removed and the product
dissolved in 50 mL of methanol. Hydrazine hydrate (9.0 mL, 87 mmol) was added and the reaction
stirred overnight. Solvent was removed under reduced pressure and the product purified by column
chromatography using 50:50 ethyl acetate/hexanes to give 2d as a light yellow powder (6.87g. 56.7
mmol. 19.8% yield based on acetonitrile). 1H NMR (CDCl3, δ downfield of TMS) 8.71 ppm (br s), 7.91
ppm (s, 1H), 2.90 (q, 2H), 1.40 (t, 3H). IR (cm-1): 2231 (vs, νCN), ESI-MS (m/z): 120.1 [pzEt,4CN]-. Elemental
Analysis calculated for C6H7N3: C, 59.48; H, 5.83; N, 34.69. Found: C, 59.37; H, 6.00; N, 34.90.
3-isopropyl-4-cyanopyrazole (HpziPr,4CN, 2e). Sodium hydride (60%, 11.52 g, 287 mmol) in a round
bottom flask was cooled using an ice-water bath and kept under nitrogen atmosphere on a Schlenk line.
Anhydrous acetonitrile (15.0 mL, 287 mmol) and 9.0 mL of anhydrous DMSO were added to the flask
and the mixture was stirred for 30 minutes. Methyl isobutyrate (33.0 mL, 29.3 g, 287 mmol) was added
to the reaction mixture. After stirring for approximately 2 hours, the reaction mixture turned into a thick
white solid. The excess NaH in the reaction mixture was quenched by slow addition of deionized water.
NH4Cl (30.7 g) was added to fully protonate the product, which immediately gave a milky white
suspension. The product was then extracted three times (150 mL each) with ethyl acetate. All organic
layers were combined and washed with NaCl brine. The organic layer was dried over anhydrous MgSO4
and filtered. To this solution was added 16.0 ml (13.1 g, 110 mmol) of DMF-DMA and the reaction was
stirred for 18 hours, after which the solvent was removed under reduced pressure and the product (2-
((dimethylamino)methylene)-4-methyl-3-oxopentanenitrile) purified by column chromatography using
CHCl3 as the mobile phase. The solvent was removed and the product dissolved in 50 mL of methanol.
Hydrazine hydrate (8.0 mL, 78 mmol) was added and the reaction stirred overnight. Solvent was
removed under reduced pressure and the product purified by column chromatography using 50:50 ethyl

acetate/hexanes to give 2e as a light yellow powder (5.86 g, 43.4 mmol, 15% yield based on
acetonitrile). 1H NMR (CDCl3, δ downfield of TMS) 7.74 ppm (br s), 7.96 ppm (s, 1H), 3.33 (m, 1H), 1.45
(d, 6H). IR (cm-1): 2232 (vs, νCN). ESI-MS (m/z): 134.1 [pziPr,4CN]-. Elemental Analysis calculated for
C7H9N3·0.25 H2O : C, 60.20; H, 6.86; N, 30.08. Found: C, 60.03; H, 6.86; N, 30.30.
3-phenyl-4-cyano-5-bromopyrazole (HpzPh,Br,4CN, 3a). To a solution of 3-phenyl-4-cyanopyrazole (7.97 g,
47.1 mmol) in methanol was slowly added two equivalents of NaOH (3.798 g, 94.95 mmol) in methanol.
Once the addition of the sodium hydroxide solution was complete, liquid bromine (3.0 mL, 59 mmol) in
methanol was added slowly. After stirring overnight, the solvent was evaporated under reduced
pressure and deionized water was added to the reaction mixture. Dilute HCl (23.5 mL of 12.1 M in 500
mL deionized water, 285 mmol) was added to neutralize the base and fully protonate the product. The
acidified reaction mixture was extracted with three 150 mL portions of ethyl acetate. The organic layers
were collected and combined, washed with NaCl brine, and dried over anhydrous MgSO4. After
filtration, the solvent was evaporated under reduced pressure to give a light yellow solid. The first
fraction from column chromatography with 50:50 ethyl acetate: hexanes as mobile phase yielded 5.60 g
(22.6 mmol, 47.9%) of 3a as a very light yellow crystalline solid. The second fraction gave 1.78 g of
recovered 3-phenyl-4-cyanopyrazole. 1H NMR (CDCl3, δ downfield of TMS) 7.51 ppm (m, 3H), 7.76 (m,
2H). IR (cm-1): 2234 (vs, νCN). ESI-MS (m/z): 248.0 [pzBr,Ph,4CN]-, 496.9 [HpzBr,Ph,4CN] + [pzBr,Ph,4CN]-, 168.1
[pzPh,4CN]-. Isotope pattern due to Br was seen in the mass spectrum. Elemental Analysis calculated for
C10H6N3Br (values in parentheses include 25% contamination with unbrominated 2a, which can be seen
in the NMR and MS): C, 48.42 (52.60); H, 2.44 (2.76); N, 16.94 (18.40). Found: C, 53.65; H, 3.22; N, 17.31.
X-ray quality crystals were grown by slow evaporation of a methanol solution. X-ray data collection and
structure solution parameters are listed in Table 1.
3-t-butyl-4-cyano-5-bromopyrazole (HpztBu,Br,4CN, 3b). To a solution of 3-tert-butyl-4-cyanopyrazole
(3.5002 g, 23.46 mmol) in methanol was slowly added two equivalents of NaOH (1.9011 g, 47.53 mmol)
dissolved in methanol. Once the addition of the sodium hydroxide solution was complete, liquid
bromine (1.30 mL, 25.2 mmol) dissolved in methanol was added slowly. After stirring overnight, the
solvent was evaporated under reduced pressure and deionized water was added to the reaction
mixture. Dilute HCl (11.8 mL of 12.1 M in 500 mL deionized water, 143 mmol ) was added to neutralize
the base and fully protonate the product. The acidified reaction mixture was extracted with three 100
mL portions of ethyl acetate. The organic layers were collected and combined and washed with NaCl
brine. Alumina was added to the organic layer and, after filtration, the solvent was evaporated under
reduced pressure to give 3.96 g (17.4 mmol, 74%) of 3b as a light yellow solid. 1H NMR (CDCl3, δ
downfield of TMS) 1.45 ppm (s, 9H). IR (cm-1): 2227 (vs, νCN). ESI-MS (m/z): 226.0 [pzBr,t-Bu,4CN]-. Isotope
pattern due to Br was seen in the mass spectrum. Elemental Analysis calculated for C8H10N3Br: C, 42.13;
H, 4.42; N, 18.42. Found: C, 42.33; H, 4.61; N, 18.26. X-ray quality crystals were grown by slow
evaporation of an ether solution. X-ray data collection and structure solution parameters are listed in
Table 1.
3-isopropyl-4-cyano-5-bromopyrazole (HpziPr,Br,4CN, 3e). To a solution of 3-isopropyl-4-cyanopyrazole
(1.04 g, 7.69 mmol) in methanol was slowly added two equivalents of NaOH (0.6833 g, 17.08 mmol) in
methanol. Once the addition of the sodium hydroxide solution was complete, liquid bromine (0.40 mL,
7.7 mmol) in methanol was added slowly. After stirring overnight, the solvent was evaporated under
reduced pressure and deionized water was added to the reaction mixture. Dilute HCl (4.24 mL of 12.1 M
in 500 mL deionized water, 51.3 mmol) was added to neutralize the base and fully protonate the
product. The acidified reaction mixture was extracted with three 100 mL portions of ethyl acetate. The
organic layers were collected and combined, and washed with NaCl brine once. Alumina was added to

the organic layer and, after filtration, the solvent was evaporated under reduced pressure to give 1.39 g
(6.49 mmol, 84.4%) of 3e as a light yellow solid. 1H NMR (CDCl3, δ downfield of TMS) 1.38 ppm (d, 6H),
3.22 ppm (m, 1H). IR (cm-1): 2237 (vs, νCN). ESI-MS (m/z): 214.0 [pzBr,i-Pr,4CN]-. Isotope pattern due to Br
was seen in the mass spectrum. Elemental Analysis calculated for C7H8N3Br: C, 39.28; H, 3.77; N, 19.63.
Found: C, 39.23; H, 3.91; N, 19.78. X-ray quality crystals were grown by slow evaporation of an ethyl
acetate solution. X-ray data collection and structure solution parameters are listed in Table 1.
3,5-diphenyl-4-cyanopyrazole (HpzPh2,4CN, 4aa). To a suspension of sodium hydride (60% dispersion in
mineral oil, 4.05 g, 101.5 mmol) in 150 mL of anhydrous toluene under nitrogen and cooled to 0 °C was
added, dropwise by syringe, a solution of 1a (14.6915 g, 101.2 mmol) in dry toluene. The mixture
immediately produced bubbles and turned light orange. The mixture was stirred for more than two
hours, becoming viscous. Benzoyl chloride (11.8 mL, 14.3 g, 102 mmol) in dry toluene was added and the
mixture immediately became less viscous, resulting in a light yellow suspension. After stirring overnight,
dilute NaOH (approx. 5.0 g, 100 mmol, in 500 mL deionized water) was added to fully deprotonate the
product. The deprotonated product was extracted with deionized water, and dilute HCl solution (31.0
mL of 12.1 M HCl in 500 mL deionized water, 374 mmol) was added to the aqueous layer to neutralize
and fully protonate the product. A white precipitate resulted immediately. The acidified reaction
mixture was extracted with three 200 mL portions of ethyl acetate. The organic layers were collected
and combined, washed with NaCl brine, and dried over anhydrous MgSO4. After filtration, the solvent
was evaporated under reduced pressure to yield 15.81 g of 2-benzoyl-3-oxo-3-phenylpropanenitrile as a
yellow solid. This crude 2-benzoyl-3-oxo-3-phenylpropanenitrile was dissolved in methanol, and
hydrazine hydrate (64%, 4.7 mL, 97 mmol) in methanol was added dropwise. After stirring overnight, the
solvent was evaporated under reduced pressure, producing a viscous yellow-brown oil. This impure
product was dissolved in 40:60 ethyl acetate:hexanes. Most of the product dissolved in this solvent
mixture leaving behind a dark red-brown oil at the bottom of the flask. The brown oil was not added to
the column during purification. Purification by column chromatography yielded 3.60 g of 4aa (14.7
mmol, 14.5% from benzoylacetonitrile) as a yellow solid. 1H NMR (CDCl3, δ downfield of TMS) 7.47 ppm
(m,6H), 7.88 ppm (m, 4H). IR (cm-1): 2227 (vs, νCN). ESI-MS (m/z): 244.1 [pzPh,Ph,4CN]-. Elemental Analysis
calculated for C16H11N3·C6H14: C, 79.72; H, 7.60; N, 12.68. Found: C, 80.75; H, 7.09; N, 12.39. X-ray quality
crystals were grown by slow evaporation of a methanol solution. X-ray data collection and structure
solution parameters are listed in Table 1.
3-phenyl-4-cyano-5-methylpyrazole (HpzPh,Me,4CN, 4ac). To a suspension of sodium hydride (60%
dispersion in mineral oil, 2.2690 g, 56.73 mmol) in 150 mL of anhydrous toluene under nitrogen and
cooled to 0 °C was added dropwise by syringe a solution of 1a (7.4234 g, 51.14 mmol) in dry toluene.
The mixture immediately produced bubbles and turned light yellow. The mixture was stirred for more
than three hours, becoming viscous. Acetyl chloride (3.65 mL, 4.01 g, 51.1 mmol) in dry toluene was
added, and the mixture immediately became less viscous and turned bright yellow. After stirring
overnight, the excess sodium hydride was quenched by adding deionized water. Dilute HCl (9.4 mL of
12.1M in 500 mL deionized water, 113 mmol) was added to neutralize the reaction and fully protonate
the product, resulting in an immediate white precipitate. The acidified reaction mixture was extracted
with three 150 mL portions of ethyl acetate. The organic layers were collected and combined, washed
with sodium chloride brine, and dried over anhydrous MgSO4. After filtration, the solvent was
evaporated under reduced pressure to yield 9.76 g of crude 2-benzoyl-3-oxobutanenitrile as a brown-
yellow oil. The crude 2-benzoyl-3-oxobutanenitrile was dissolved in methanol, and hydrazine hydrate
(64%, 4.0 mL, 82 mmol) in methanol was added dropwise. After stirring overnight, the solvent was
evaporated under reduced pressure, producing a brown oily product. This impure product was dissolved
in 40:60 ethyl actetate:hexanes. Most of the product dissolved in this solvent mixture, leaving behind a

dark red-brown oil at the bottom of the flask. The brown oil was not added to the column during
purification. Purification by column chromatography produced 2.00 g (10.9 mmol, 21.4% from
benzoylacetonitrile) of 4ac as a light yellow solid. 1H NMR (CDCl3, δ downfield of TMS) 2.45 ppm (s, 3H),
7.45 ppm (m, 3H), 7.84 ppm (m, 2H). IR (cm-1): 2228 (vs, νCN). ESI-MS (m/z): 182.1 [pzPh,Me,4CN]-, 365.2
[HpzPh,Me,4CN] + [pzPh,Me,4CN]-. Elemental Analysis calculated for C11H9N3·0.25 Et2O : C, 71.44; H, 5.75; N,
20.70. Found: C, 72.14; H, 5.72; N, 20.70. X-ray quality crystals were grown by slow evaporation of an
ether solution. X-ray data collection and structure solution parameters are listed in Table 1.
3-phenyl-4-cyano-5-ethylpyrazole (HpzPh,Et,4CN, 4ad). To a suspension of sodium hydride (60% dispersion
in mineral oil, 5.63865 g, 141 mmol) in 100 mL of anhydrous toluene under nitrogen atmosphere and
cooled to 0 °C was added dropwise by syringe a solution of 1a (20.3824 g, 140.4 mmol) in dry toluene.
The mixture immediately produced bubbles and turned light yellow. The mixture was stirred for more
than three hours, becoming viscous. Propionyl chloride (12.26 mL, 12.99 g, 140.4 mmol) in dry toluene
was added, and the mixture immediately became less viscous and turned into a light yellow suspension.
After stirring overnight, excess NaH is neutralized by slowly adding deionized water, and dilute NaOH
(approx. 6.0 g, 150 mmol in 600 mL deionized water) was added to fully deprotonate the product. The
deprotonated product was extracted with deionized water (three times, 200 mL each). To the aqueous
layer, dilute HCl (37.3 mL of 12.1 M HCl in 500 mL deionized water, 452 mmol) was added to neutralize
and fully protonate the product. The acidified reaction mixture was extracted with three 150 mL
portions of ethyl acetate. The organic layers were collected and combined, washed with NaCl brine, and
dried over anhydrous MgSO4. After filtration, the solvent was evaporated under reduced pressure to
yield 2-benzoyl-3-oxopentanenitrile (13.04 g) as a dark brown-yellow liquid, which solidified upon
standing. This crude 2-benzoyl-3-oxopentanenitrile was dissolved in methanol, and hydrazine hydrate
(64%, 6.30 mL, 130 mmol) in methanol was added dropwise. After stirring overnight, the solvent was
evaporated under reduced pressure, producing a viscous yellow-brown oil. This impure product was
dissolved in 40:60 ethyl actetate:hexanes. Most of the product dissolved in this solvent mixture leaving
behind a dark red-brown oil at the bottom of the flask. The brown oil was not added to the column
during purification. Purification by column chromatography produced 1.10 g (5.58 mmol, 3.95% from
benzoylacetonitrile) of 4ad as a yellow solid. 1H NMR (CDCl3, δ downfield of TMS) 1.34 ppm (t, 3H), 2.82
ppm (q, 2H), 7.44 ppm (m, 3H), 7.82 ppm (m, 2H), 9.20 ppm (N-H, broad, s). IR (cm-1): 2224 (vs, νCN). ESI-
MS (m/z): 196.1 [pzPh,Et,4CN]-, 393.3 [HpzPh,Et,4CN] + [pzPh,Et,4CN]-. Elemental Analysis calculated for
C12H11N3·0.5 H2O: C, 69.88; H, 5.86; N, 20.37. Found: C, 69.96; H, 5.76; N, 20.13. X-ray quality crystals
were grown by slow evaporation of a 40:60 ethyl acetate:hexanes solution. X-ray data collection and
structure solution parameters are listed in Table 1.
3-t-butyl-4-cyano-5-phenylpyrazole (HpztBu,Ph,4CN, 4ba). To a suspension of sodium hydride (60%
dispersion in mineral oil, 4.2118 g, 105.29 mmol) in 150 mL of anhydrous toluene under nitrogen and
cooled to 0 °C was added dropwise by syringe a solution of pivaloylacetonitrile (13.1770 g, 105.3 mmol)
in dry toluene. The mixture was stirred for more than two hours, becoming a very viscous white
suspension Benzoyl chloride (12.23 mL, 14.80 g, 105.3 mmol) in dry toluene was added and the mixture
immediately became less viscous. After stirring overnight, the resulting light yellow-orange suspension
was treated with dilute NaOH (approx. 5.02 g, 126 mmol in 600 ml deionized water) to fully deprotonate
the product. The deprotonated product was then extracted with deionized water, and dilute HCl (31.1
mL of 12.1 M HCl in 500 mL deionized water, 377 mmol) was added to the light yellow aqueous layer to
neutralize and fully protonate the product, resulting immediately in a white precipitate. The acidified
reaction mixture was extracted with three 200 mL portions of ethyl acetate. The organic layers were
collected and combined, washed with NaCl brine, and dried over anhydrous MgSO4. After filtration, the
solvent was evaporated under reduced pressure to yield 17.65 g of 2-benzoyl-4,4-dimethyl-3-

oxopentanenitrile as a yellow oily liquid. The crude 2-benzoyl-4,4-dimethyl-3-oxopentanenitrile was
dissolved in methanol, and hydrazine hydrate (64%, 7.5 mL, 155 mmol) in methanol was added
dropwise. After stirring overnight, the solvent was evaporated under reduced pressure, producing a light
yellow oil. This impure product was then dissolved in 40:60 ethyl actetate:hexanes. Most of the product
dissolved in this solvent mixture leaving behind a dark red-brown oil at the bottom of the flask. The
brown oil was not added to the column during purification. Purification by column chromatography
produced 7.78 g (34.5 mmol, 32.8% from pivaloylacetonitrile) of 4ba as an off-white solid. 1H NMR
(CDCl3, δ downfield of TMS): 1.50 ppm (s, 9H), 7.44 ppm (m, 3H), 7.84 ppm (m, 2H). IR (cm-1): 2223 (vs,
νCN). ESI-MS (m/z): 224.1 [pzt-Bu,Ph,4CN]-. Elemental Analysis calculated for C14H15N3: C, 74.64; H, 6.71; N,
18.65. Found: C, 74.53; H, 6.90; N, 18.49. X-ray quality crystals were grown by slow evaporation of an
ether solution. X-ray data collection and structure solution parameters are listed in Table 1.
3,5-di(t-butyl)-4-cyano-pyrazole (HpztBu2,4CN, 4bb). To a suspension of sodium hydride (60% dispersion in
mineral oil, 4.5390 g, 113.48 mmol) in 150 mL of anhydrous toluene under nitrogen and cooled to 0 °C
was added dropwise by syringe a solution of pivaloylacetonitrile (14.2015 g, 113.46 mmol) in dry
toluene. The mixture was stirred for more than two hours, becoming a very viscous white suspension.
Trimethyl acetyl chloride (14.0 mL, 13.74 g, 114 mmol) in dry toluene was added, and the mixture
immediately became less viscous. After stirring overnight, it became a light yellow suspension. Dilute
NaOH (approx. 5.16 g, 129 mmol in 600 ml deionized water) was added to fully deprotonate the
product. The deprotonated product was extracted with deionized water. To the light yellow aqueous
layer, dilute HCl (32.0 mL of 12.1 M HCl in 500 mL deionized water, 387 mmol) was added to neutralize
and fully protonate the product, resulting in an immediate white precipitate. The acidified reaction
mixture was extracted with three 200 mL portions of ethyl acetate. The organic layers were collected
and combined, washed with NaCl brine, and dried over anhydrous MgSO4. After filtration, the solvent
was evaporated under reduced pressure to yield 8.50 g of 4,4-dimethyl-3-oxo-2-pivaloylpentanenitrile
as a light yellow oily liquid, which solidified upon standing. The crude 4,4-dimethyl-3-oxo-2-
pivaloylpentanenitrile was dissolved in methanol, and hydrazine hydrate (64%, 4.0 mL, 82 mmol) in
methanol was added dropwise. After stirring overnight, the solvent was evaporated under reduced
pressure, producing a bright yellow crystalline solid. This impure product was dissolved in 40:60 ethyl
actetate:hexanes. Most of the product dissolved in this solvent mixture leaving behind a dark red-brown
oil at the bottom of the flask. The brown oil was not added to the column during purification.
Purification by column chromatography produced 4.10 g (20.0 mmol, 17.6% from pivaloylacetonitrile) of
4bb as a light yellow crystalline solid. 1H NMR (CDCl3, δ downfield of TMS): 1.43 ppm (s, 18H). IR (cm-1):
2223 (vs, νCN). ESI-MS (m/z): 204.2 [pzt-Bu,t-Bu,4CN]-. Elemental Analysis calculated for C12H19N3: C, 70.20; H,
9.33; N, 20.47. Found: C, 70.09; H, 9.26; N, 20.47. X-ray quality crystals were grown by slow evaporation
of an ether solution. X-ray data collection and structure solution parameters are listed in Table 1.
3-t-butyl-4-cyano-5-methylpyrazole (HpztBu,Me,4CN, 4bc). To a suspension of sodium hydride (60%
dispersion in mineral oil, 7.1851 g, 179.6 mmol) in 200 mL of anhydrous toluene under nitrogen and
cooled to 0 °C was added dropwise by syringe a solution of pivaloylacetonitrile (22.4897 g, 179.6 mmol)
in dry toluene. The mixture was stirred for more than 4.5 hours, becoming a very viscous white
suspension. Acetyl chloride (13.0 mL, 14.3 g, 182 mmol) in dry toluene was added and the mixture
immediately became less viscous. After stirring overnight, the resulting light yellow suspension was
treated with dilute NaOH (approx. 6.53 g, 163 mmol in 600 ml deionized water) to fully deprotonate the
product. The deprotonated product was extracted with deionized water. To the light yellow aqueous
layer, dilute HCl (41.0 mL of 12.1 M HCl in 500 mL deionized water, 496 mmol) was added to neutralize
and fully protonate the product, resulting in an immediate white precipitate. The acidified reaction
mixture was extracted with three 200 mL portions of ethyl acetate. The organic layers were collected

and combined, washed with sodium chloride brine, and dried over anhydrous MgSO4. After filtration,
the solvent was evaporated under reduced pressure to yield 7.51 g of 2-acetyl-4,4-dimethyl-3-
oxopentanenitrile as an oily yellow liquid. The crude 2-acetyl-4,4-dimethyl-3-oxopentanenitrile was
dissolved in methanol, and hydrazine hydrate (64%, 3.27 mL, 67.4 mmol) in methanol was added
dropwise. After stirring overnight, the solvent was evaporated under reduced pressure, producing an
oily product. The impure product was dissolved in 40:60 ethyl actetate:hexanes. Most of the product
dissolved in this solvent mixture leaving behind a dark red-brown oil at the bottom of the flask. The
brown oil was not added to the column during purification. Purification by column chromatography
produced 1.81 g (11.1 mmol, 6.2% from pivaloylacetonitrile) of 4bc as a light yellow crystalline product.
1H NMR (CDCl3, δ downfield of TMS): 1.41 ppm (s, 9H), 2.38 ppm (3H). IR (cm-1): 2223 (vs, νCN). ESI-MS
(m/z): 162.2 [pzt-Bu,Me,4CN]-. Elemental Analysis calculated for C9H13N3: C, 66.23; H, 8.03; N, 25.74. Found:
C, 66.36; H, 8.13; N, 25.65. X-ray quality crystals were grown by slow evaporation of an ether solution. X-
ray data collection and structure solution parameters are listed in Table 1.
3-t-butyl-4-cyano-5-isopropylpyrazole (HpztBu,iPr,4CN, 4be). To a suspension of sodium hydride (60%
dispersion in mineral oil, 4.7315 g, 118.29 mmol) in 150 mL of anhydrous toluene under nitrogen and
cooled to 0 °C was added dropwise by syringe a solution of pivaloylacetonitrile (14.8080 g, 118.30 mmol)
in dry toluene. The mixture was stirred for more than two hours, becoming a very viscous white
suspension. Isobutyryl chloride (12.4 mL, 12.6 g, 118 mmol) in dry toluene was added and the mixture
immediately became less viscous and light yellow. After stirring overnight, dilute NaOH (approx. 5.15 g,
129 mmol in 600 ml deionized water) was added to fully deprotonate the product. The deprotonated
product was extracted with deionized water. To the slightly brown-yellow aqueous layer, dilute HCl
(31.9 mL of 12.1 M HCl in 500 mL deionized water, 386 mmol) was added to neutralize and fully
protonate the product, resulting in an immediate white precipitate. The acidified reaction mixture was
extracted with three 200 mL portions of ethyl acetate. The organic layers were collected and combined,
washed with sodium chloride brine, and dried over anhydrous MgSO4. After filtration, the solvent was
evaporated under reduced pressure to yield 13.2 g of 2-isobutyryl-4,4-dimethyl-3-oxopentanenitrile as
an oily brown liquid. The crude 2-isobutyryl-4,4-dimethyl-3-oxopentanenitrile was dissolved in
methanol, and hydrazine hydrate (64%, 6.6 mL, 136 mmol) in methanol was added dropwise. After
stirring overnight, the solvent was evaporated under reduced pressure, producing a bright yellow
crystalline solid. This impure product was dissolved in 40:60 ethyl actetate:hexanes. Most of the product
dissolved in this solvent mixture leaving behind a dark red-brown oil at the bottom of the flask. The
brown oil was not added to the column during purification. Purification by column chromatography
produced 4.61 g (24.1 mmol, 20.4 % from pivaloylacetonitrile) of 4be as a white solid. 1H NMR (CDCl3, δ
downfield of TMS): 1.35 ppm (d, 6H), 1.43 ppm (s, 9H), 3.14 ppm (m, 1H). IR (cm-1): 2223 (vs, νCN). ESI-MS
(m/z): 190.2 [pzt-Bu,i-Pr,4CN]-, 381.3 [Hpzt-Bu,i-Pr,4CN] + [pzt-Bu,i-Pr,4CN]-. Elemental Analysis calculated for
C11H17N3: C, 69.07; H, 8.96; N, 21.97. Found: C, 69.30; H, 9.08; N, 22.12. X-ray quality crystals were grown
by slow evaporation of a toluene solution. X-ray data collection and structure solution parameters are
listed in Table 1.
Scorpionate synthesis:
Method A. Potassium borohydride (~ 0.25 g) and 4 equivalents of the appropriate pyrazole were mixed
together using a mortar and pestle and placed in a round-bottom flask fitted with a reflux condenser.
The mixture was heated over a period of one hour, with stirring, to 210 °C using a silicone oil bath. At
about 160 °C, the pyrazole started to melt and hydrogen gas evolution began. The temperature was kept
at 210 °C for another hour, after which the melted reaction mixture was washed with hot toluene to
remove unreacted pyrazole. The remaining solid was dissolved in methanol and the solvent was

removed under reduced pressure to yield a colorless oily product. To this, ether was added to produce a
white precipitate. This was left in the refrigerator overnight and the solid Tp was isolated by filtration.
Potassium Hydrotris(3-tert-butyl-4-cyano-5-phenyl)pyrazolylborate (KTpt-Bu,Ph,4CN, 5ba). KBH4 (0.2402 g,
4.45 mmol) and 4.0013 g (17.76 mmol) of Hpzt-Bu,Ph,4CN yielded 2.08 g (2.87 mmol, 64.6%) of KTpt-Bu,Ph,4CN
IR(cm-1): 2220 (vs, νCN), 2489 (m, νBH). ESI-MS (MeOH, m/z): 684.3 [Tpt-Bu,Ph,4CN]-, 461.2 [Bpt-Bu,Ph,4CN]-. The
product was crystallized by vapor diffusion of methanol/THF.
.
Potassium Hydrotris(3-tert-butyl-4-cyano-5-bromo)pyrazolylborate (KTpt-Bu,Br,4CN, 6b). KBH4 (0.2200 g,
4.08 mmol) and 3.64 g (16.0 mmol) of Hpzt-Bu,Br,4CN yielded 1.61g (2.20 mmol, 53.9%) of KTpt-Bu,Br,4CN
.
IR(cm-1): 2225 (vs, νCN), 2473 (m, νBH). ESI-MS (MeOH, m/z): 691.9 [Tpt-Bu,Br,4CN]-, 614.0 [HB(pzt-Bu,Br,4CN)2(pzt-
Bu,4CN)]-, 536.1 [HB(pzt-Bu,Br,4CN)(pzt-Bu,4CN)2]-, 456.2 [Tpt-Bu,4CN]-. The product was crystallized by slow
evaporation of 80:20 methanol:toluene.
Method B. Potassium borohydride (0.2 – 0.5g) and approximately 3.2 equivalents of the appropriate
pyrazole were combined in round-bottom flask and 30 - 60 mL of tetradecane was added. This was fitted
with a reflux condenser and slowly heated, with stirring over a period of one hour, to 210 - 220 °C using
a silicone oil bath. At 140 - 170 °C, the pyrazole started to melt and hydrogen gas started to evolve. By
185 °C, all solids had dissolved in tetradecane. The temperature was kept at 210 – 220 °C for another
hour. At this point, solid started to appear on the side of the flask. After the heating was complete, the
reaction was allowed to cool to room temperature, resulting in a white precipitate, which was isolated
by filtration. The resulting solid was dissolved in acetonitrile and filtered in order to remove any
unreacted potassium borohydride. The acetonitrile was removed under reduced pressure to obtain solid
mixture of Tp and any unreacted pyrazole. To this solid was added ether to dissolve any unreacted
pyrazole. After sitting in the refrigerator overnight, the solid Tp was collected by filtration.
Potassium Dihydrobis(3-tert-butyl-4-cyano-5-methyl)pyrazolylborate (KBpt-Bu,Me,4CN, 7bc). KBH4 (0.0957
g, 1.77 mmol) and 0.94 g (5.76 mmol) of Hpzt-Bu,Me,4CN yielded 0.46 g (1.22 mmol, 69.1%) of KBpt-Bu,Me,4CN
IR(cm-1): 2218(vs, νCN), 2427 (m, νBH). TOF-MS (MeOH, m/z): 337.2 [Bpt-Bu,Me,4CN]-, 162.1 [pzt-Bu,Me,4CN]-,
498.3 [Tpt-Bu,Me,4CN]- (negligible).
.
Potassium Hydrotris(3-phenyl-4-cyano)pyrazolylborate (KTpPh,4CN, 5a). KBH4 (0.4286 g, 7.95 mmol) and
4.3580 g (25.76 mmol) of HpzPh,4CN yielded 4.09 g (7.36 mmol, 92.6%) of KTpPh,4CN . IR(cm-1): 2225 (vs, νCN),
2426 (m, νBH). ESI-MS (MeOH, m/z): 515.9 [TpPh,4CN]-, 348.9 [BpPh,4CN]-, 167.9 [pzPh,4CN]-. Elemental Analysis
calculated for C30H19N9BK : C,64.87; H, 3.45; N, 22.70. Found: C, 65.00; H, 3.70; N, 22.51.
Potassium Hydrotris(3-tert-butyl-4-cyano)pyrazolylborate (KTpt-Bu,4CN, 5b). KBH4 (0.5190 g, 9.62 mmol)
and 5.0092 g (33.57 mmol) of Hpzt-Bu,4CN yielded 3.04 g (6.12 mmol, 63.8%) of KTpt-Bu,4CN. IR(cm-1): 2227
(vs, νCN), 2461 (m, νBH). ESI-MS (MeOH, m/z): 456.1 [Tpt-Bu,4CN]-, 308.9 [Bpt-Bu,4CN]-. Elemental Analysis
calculated for C24H31N9BK: C, 58.18; H, 6.31; N, 25.44. Found: C, 57.91; H, 6.49; N, 25.30.
Potassium Hydrotris(3-phenyl-4-cyano-5-methyl)pyrazolylborate (KTpPh,Me,4CN, 5ac ). KBH4 (0.1573 g,
2.92 mmol) and 1.17 g (9.33 mmol) of HpzPh,Me,4CN yielded 1.47 g (2.46 mmol, 84.3%) of KTpPh,Me,4CN
IR(cm-1): 2221 (vs, νCN), 2428 (m, νBH). ESI-MS (MeOH, m/z): 558.1[TpPh,Me,4CN]-, 377.2 [BpPh,Me,4CN]-,
182.1[pzPh,Me,4CN]-, and 957.9 [TpPh,Me,4CN]- + [BpPh,Me,4CN]- + Na+. Elemental Analysis calculated for
C33H25N9BK·CH3CN·0.4C14H30 : C, 67.92; H, 5.62; N, 20.57. Found: C, 68.72; H, 4.87; N, 20.57.
.

Potassium Hydrotris(3-phenyl-4-cyano-5-bromo)pyrazolylborate (KTpPh,Br,4CN, 6a). KBH4 (0.3365 g, 6.24
mmol) and 5.0008 g (20.16 mmol) of HpzPh,Br,4CN yielded 3.57 g (4.51 mmol, 72.2%) of KTpPh,Br,4CN. IR(cm-
1): 2231 (vs, νCN), 2519 (m, νBH). TOF-MS (MeOH, m/z): 753.9 [TpBr,Ph,4CN]-, 245.9 [pzBr,Ph,4CN]-. Isotopic
pattern due to Br was seen in the mass spectrum. Elemental Analysis calculated for
C30H16N9BK·2CH3CN·0.4C14H30 : C, 49.88; H, 3.59; N, 16.16. Found: C, 50.93; H, 2.84; N, 17.13.
Potassium Hydrotris(3-tert-butyl-4-cyano-5-isopropyl)pyrazolylborate (KTpt-Bu,iPr,4CN, 5be). KBH4 (0.2223
g, 4.12 mmol) and 2.6004 g (13.59 mmol) of Hpzt-Bu,iPr,4CN yielded 1.79 g (2.88 mmol, 70.0%) of KTpt-
Bu,iPr,4CN. IR(cm-1): 2215 (vs, νCN), 2419 (m, νBH). TOF-MS (MeOH, m/z): 582.4 [Tpt-Bu,i-Pr,4CN]-, 393.3 [Bpt-Bu,i-
Pr,4CN]-, 190.1 [pzt-Bu,i-Pr,4CN]-. Elemental Analysis calculated for C33H49N9BK·2H2O: C, 60.26; H, 8.12; N,
19.17. Found: C, 60.91; H, 7.05; N, 19.10.
(Bpt-Bu,Me,4CN)2[Ni(cyclam)] (8). [Ni(cyclam)(ClO4)2] was synthesized according to the published literature
method. [28] To a solution of [Ni(cyclam)(ClO4)2] (0.0642 g, 0.140 mmol) in 40 mL of dry THF was added
KBpt-Bu,Me,4CN (0.1507 g, 0.400 mmol), in 50 mL of THF. The mixture was stirred for about an hour and the
solvent was removed under reduced pressure to produce a light brown/yellow solid. The solid was
redissolved in dichloromethane and filtered, yielding a light brown/yellow solution and a small amount
of similarly colored precipitate. The filtrate was allowed to sit for a day, resulting in yellow/brown
crystals. X-ray data collection was performed on the crystal, which verified the structure as (Bpt-
Bu,Me,4CN)2[Ni(cyclam)]. IR (cm-1): 2434 (νBH, w), 2214 (νCN, s). ESI-MS (CH2Cl2, m/z): 337.2 [Bpt-Bu,Me,4CN -
]
,697.2 2.[Bpt-Bu,Me,4CN]- + Na+, 498.3 [Tpt-Bu,Me,4CN]-(minor peak). Elemental Analysis calculated for
C46H76N16B2Ni·2 H2O : C, 56.99; H, 8.32; N, 23.11. Found: C, 56.60; H, 7.54; N, 24.12. X-ray data collection
and structure solution parameters are listed in Table 3.
3. Results and Discussion
Synthesis of cyanopyrazoles
To date, our method for synthesizing cyanopyrazoles has been a modification of that reported by
Tupper and Bray, [29] in which t-butylcyanoacetate is combined with the appropriate acyl chloride
(Scheme 1, top left) to produce, after deprotection and decarboxylation, an acylacetonitrile
intermediate. The acylacetonitrile is then converted to the pyrazole in two steps by reaction with
dimethylformamide-dimethylacetal (DMF-DMA) and then with hydrazine monohydrate. The initial
report by Tupper and Bray was for the synthesis of 3-phenyl-4-cyanopyrazole and we were also able to
successfully use this method for the synthesis of 3-t-butyl-4-cyanopyrazole. [30] However, synthesis of
4-cyanopyrazoles containing a substituent in the 3-position with an α-hydrogen proved problematic
using this method, which also was not suitable for 4-cyanopyrazoles with additional substitution at both
the 3- and 5-positions. The key intermediate in this synthesis is the acylacetonitrile species, 1, but the t-
butylcyanoacetate reagent used in the Tupper/Bray synthesis is rather toxic and quite expensive. While
pivolylacetonitrile (1b, R3 = t-butyl) is commercially available at a reasonable price, benzoylacetonitrile
(1a, R3 = Ph) is relatively expensive, as are other commercially available analogs (e.g., R = Me, Et, i-Pr). A
relatively straightforward synthesis of these compounds is available by reacting the appropriate methyl
ester with deprotonated acetonitrile in the presence of DMSO. This method has expanded the range of
acylacetonitrile compounds, and ultimately the availability of substituents at the 3-position in 4-
cyanopyrazoles, to include methyl, ethyl, and isopropyl. Synthesis of benzoylacetonitrile by this method

was also found to be more efficient, requiring shorter reaction times and producing a higher purity
product with higher and better yields than the t-butylcyanoacetate route. Following the remainder of
the Tupper/Bray synthesis using these acylacetonitrile derivatives, we have successfully isolated 3-R-4-
cyanopyrazoles with R = ethyl (2d) and isopropyl (2e) in addition to the previously reported phenyl (2a)
and t-butyl (2b) derivatives (Scheme 1, top). The compound with R=methyl has been reported using
other synthetic procedures. [31-33]
Scheme 1. Synthesis of substituted 4-cyanopyrazoles.
In order to access the trisubstituted pyrazoles, two approaches were used. For 4-cyanopyrazoles with
alkyl/aryl substituents in the 3-position and bromo substituents in the 5-position (Scheme 1, top right),
the 3-R-4-cyanopyrazoles were subjected to bromination reactions using elemental bromine, resulting in
the isolation of the 3-R-4-cyano-5-bromopyrazoles (R = Ph (3a), t-Bu (3b), and isopropyl (3e)). The
bromination reaction to produce 3a appears not to have been quantitative, as MS and 1H NMR show
evidence of 2a and the elemental analysis is consistent with a mixture of 2a and 3a. To synthesize 4-
cyanopyrazoles with alkyl or aryl substituents at both the 3- and 5-positions (Scheme 1, bottom), the
acylacetonitrile derivatives, 1, were reacted with acid chlorides and hydrazine monohydrate, resulting in
the isolation of seven 3-R-4-cyano-5-R’-pyrazoles, 4. Of these trisubstituted pyrazoles, 4aa and 4ac have
been previously reported [34-37] – the others have, to the best of our knowledge, not been reported.

Table 1. Data Collection and Structure Solution Parameters for Cyanopyrazoles
Compound
formula
fw
temp, K
color
2d
2e
3a
3b
3e
C6H7N3
121.15
150
C7H9N3
135.17
150
C10H6BrN3
248.09
150
C8H10BrN3
228.10
150
C7H8BrN3
214.07
150
colorless
colorless
colorless
colorless
colorless
habit
block
rod
needle
block
plate
crystal system
space group
dimen, mm
min
mid
max
a, Å
b, Å
Monoclinic
C2/c
Triclinic
P-1
orthorhombic
P212121
monoclinic
P21/m
monoclinic
P21/m
0.314
0.375
0.839
0.370
0.647
0.971
0.342
0.526
0.774
5.1487(10)
9.2353(18)
20.436(4)
90
90
90
971.7(3)
4
1.696
4.189
0.418
0.424
0.731
7.625(2)
7.263(2)
9.029(2)
90
104.22(2)
90
484.7(2)
2
0.264
0.397
0.873
7.579(3)
6.879(3)
8.940(4)
90
105.63(3)
90
448.9(4)
2
21.898(6)
12.722(3)
15.660(4)
90
114.14(2)
90
3981(2)
24
1.213
10.726(7)
12.734(7)
12.762(7)
68.79(4)
78.35(4)
77.10(5)
1570.0(16)
8
c, Å
α, deg
β, deg
γ, deg
V, Å3
Z
ρcalc, g cm-3
µ, mm-1
unique refls (Rint)
obs refls, I>2σ(I)
parameters
R, Rw
1.144
0.074
1.563
4.194
1.584
4.520
0.080
4188 (0.0917) 6549 (0.1082) 2145 (0.0779) 1199 (0.0506) 863 (0.1087)
1460
266
2185
368
1729
127
885
71
459
78
0.0898, 0.2314 0.1000, 0.2539 0.0341, 0.0779 0.0354, 0.0925 0.0565, 0.1457
gof
0.975
1.00,0.8331
0.30/-0.29
1.018
1.000/0.8137
0.62/-0.81
1.018
0.7335, 0.4837 0.3411, 0.1687 0.415, 0.100
0.34/-0.46 0.64/-0.34 0.51/-0.47
1.030
1.067
Tmax, Tmin
ρmax, ρmin, e Å-3

Table 1 (cont). Data Collection and Structure Solution Parameters for Cyanopyrazoles
Compound
formula
fw
temp, K
color
4aa
4ac
4ad
4ba
4bb
4bc
4be
C16H11N3
245.28
150
lt. yellow
needle
triclinic
P-1
C11H9N3
183.21
150
lt. yellow
block
C12H11N3
197.24
150
lt. yellow
block
C14H15N3
225.29
150
colorless
block
C12H19N3
205.30
150
colorless
block
C9H13N3
163.22
150
colorless
block
C11H17N3
191.27
150
colorless
block
habit
crystal system
space group
dimen, mm
min
mid
max
a, Å
b, Å
monoclinic
P21/n
tetragonal
P-421c
orthorhombic
Pbca
monoclinic
P21/c
monoclinic
C2/m
monoclinic
P21/c
0.196
0.364
0.589
0.362
0.559
0.561
8.616(4)
9.517(4)
11.634(5)
90
91.34(3)
90
953.7(7)
4
0.356
0.447
0.558
9.9142(17)
9.9142(17)
21.731(4)
90
90
90
2136.0(8)
8
0.498
0.541
0.559
11.905(2)
12.925(3)
16.878(4)
90
90
90
2597.1(9)
8
0.396
0.456
0.491
10.719(2)
10.0275(19)
12.485(3)
90
109.663(10)
90
0.576
0.616
0.736
0.415
0.508
0.595
9.7385(9)
10.6454(11)
13.5186(13)
74.025(6)
73.258(5)
89.672(6)
1286.1(2)
4
12.079(3)
7.131(3)
12.478(4)
90
114.32(3)
90
979.5(6)
4
1.107
10.596(3)
9.955(3)
12.376(3)
90
109.446(13)
90
1230.9(5)
4
1.032
c, Å
α, deg
β, deg
γ, deg
V, Å3
1263.7(4)
4
Z
ρcalc, g cm-3
µ, mm-1
1.267
1.276
1.227
1.152
1.079
0.078
0.080
0.076
0.071
0.066
0.070
0.064
unique refls (Rint) 5694 (0.0647) 2076 (0.0647) 2358 (0.0578) 2874 (0.0608)
2791 (0.0537) 982 (0.1040)
2699 (0.0530)
1280
143
obs refls, I>2σ(I) 2953
1252
128
1552
137
1660
157
1946
142
774
73
parameters
R, Rw
343
0.0556, 0.1373 0.0689, 0.1981 0.0612, 0.1661 0.0603, 0.1555 0.0635, 0.1779 0.0579, 0.1544 0.0953, 0.2861
1.066 1.025 1.075 1.039 1.073 1.065 1.132
1.0000, 0.9176 1.0000, 0.7993 0.9907, 0.9269 1.0000, 0.7823 0.7455, 0.6791 0.2590, 0.1422 1.0000, 0.9514
0.33, -0.29 0.36, -0.53 0.28/-0.30 0.27/-0.34 0.33/-0.37 0.17/-0.20 0.37/-0.28
gof
Tmax, Tmin
ρmax, ρmin, e Å-3

Structures of cyanopyrazoles
The cyanopyrazoles crystallize in a variety of space groups, as indicated in Table 1. Representative
thermal ellipsoid diagrams of 3e and 4ba are shown in Figure 1 and diagrams of the rest of the
cyanopyrazoles can be obtained via the CIF files in the supporting material. Data collection and structure
solution parameters for all the cyanopyrazole structures are given in Table 1 and selected bond
distances and angles are given in Table 2. Compounds 3b, 3e, and 4bc crystallize with the plane of the
pyrazole coincident with a crystallographic mirror plane. In 3b and 4bc, one of the t-Bu methyl groups
lies in the plane with the other two above and below the plane. In 3e, the central C atom of the i-Pr
group and one of the methyl groups are essentially on the crystallographic plane, but they refined better
when positioned slightly out of the plane – the other methyl group is disordered 50% to either side of
the plane. The rest of the cyanopyrazole structures involve molecules crystallizing on general positions.
In the structure of 4be, one methyl group of the isopropyl substituent is disordered over two positions,
as is the ethyl substituent in 2d. In the structure of 4aa, the asymmetric unit contains two molecules of
the pyrazole.
N1
N2
N1
N2
Br1
N3
N3
Figure 1. Plot showing the 50% thermal ellipsoids for 3e (left) and 4ba (right). H atoms have been
omitted for clarity.
Table 2. Selected bond distances (Å) and angles (°) for cyanopyrazoles
2d
2e
3a
3b
3e
N1–N2
C4–N3
1.357(5)
1.142(5)
109.3(4)
108.5(4)
179.0(6)
2.867(6)
168.4(3)
1.364(7) 1.349(5)
1.144(8) 1.133(6)
109.5(4) 113.9(3)
108.4(5) 104.5(3)
178.5(6) 177.0(6)
2.868(7) 2.910(5)
1.367(5)
1.140(6)
113.8(3)
103.5(3)
179.9(4)
2.944(5)
154.5(2)
1.338(9)
1.128(10)
115.2(6)
103.1(7)
177.6(11)
2.93(1)
C1–N1–N2
C3–N2–N1
C2–C4–N3
N1…Nx’
N1–H1…Nx’
147.0,
167.5
153.6(2)
158.8(5)
pz/Ph dihed
5.17
4aa
1.357(2)
1.144(3)
110.6(2)
108.8(2)
179.3(2)
2.823(2)
131.1
4ac
4ad
4ba
4bb
4bc
4be
N1–N2
C4–N3
1.359(3)
1.145(3)
113.9(2)
105.1(2)
178.3(3)
2.938(3)
167.6
1.373(4) 1.360(2)
1.133(5) 1.135(3)
112.5(3) 113.9(1)
105.7(2) 105.5(1)
178.0(6) 179.2(2)
2.892(4) 2.861(2)
1.3676(19) 1.371(3)
1.357(3)
1.124(4)
110.5(2)
108.8(2)
179.3(4)
2.890(3)
133.7(2)
1.138(3)
109.9(1)
109.3(1)
179.5(2)
2.934(2)
128.0
1.143(3)
105.3(2)
113.3(2)
179.5(3)
2.843
C1–N1–N2
C3–N2–N1
C2–C4–N3
N1…Nx’
N1–H1…Nx’
pz/Ph dihed
158.24
21.16
136.4
31.58
134.7
24.80,21.89, 0.77
20.33, 35.28

Two structural features bear mentioning. The first relates to the compounds which have phenyl
substituents, in which the dihedral angle between the plane of the pyrazole ring and that of the phenyl
ring ranges from almost coplanar (dihedral angle of 0.77° in 4ac) to a dihedral angle of 35.28° for one of
the phenyl rings in 4aa.
The second structural feature is intermolecular hydrogen bonding. All the cyanopyrazole structures
show intermolecular hydrogen bonding of some type – in fact there are six varieties of hydrogen
bonding represented among the 15 structures. The most prevalent – displayed by five of the structures
(4aa, 4ba, 4bb, 4bc, and 4be) is the dimeric structure (Figure 2, left) in which two inversion symmetry-
related molecules simultaneously donate their N-H bond to the unprotonated pyrazole N atom of the
other molecule. A second motif is evident in the structure of 2d, which displays a cyclic trimeric
hydrogen bonding motif (Figure 2, right), in which one pyrazole is a hydrogen bond donor to a second
pyrazole and a hydrogen bond acceptor from a third pyrazole. The three pyrazoles are all coplanar. The
trimers are then linked into a two-dimensional sheet via hydrogen bond interaction between the cyano
N atom on a pyrazole in one trimer and and a C-H group from a pyrazole in a neighboring trimer– all
three cyano groups in a trimer display such an interaction. In two of the structures (2e and 4ad), four
N6
N1
N4
N5
N7
N2
N2
N3
N1
N3
N8
N9
Figure 2. Plots showing the hydrogen bonding motifs – dimer in 4bb (left) and two linked trimers in 2d
(right)
pyrazole molecules form a hydrogen-bonded cyclic tetramer (Figure 3, left), with each pyrazole situated
at one corner of a tetrahedron. In 4ad this tetrahedral relationship is exact, as the four pyrazoles are
related by a crystallographic 4-bar axis. In 2e, the four pyrazoles are crystallographically independent and
the tetrahedral symmetry is approximate. In 3a, the hydrogen-bonding motif results in an infinite chain of
pyrazole molecules (Figure 3, right), with the protonated pyrazole N atom of one pyrazole molecule
serving as hydrogen-bond donor to the unprotonated pyrazole N atom of a 21-related molecule. This
motif results in two sets of molecules which are approximately perpendicular to each other.

Br1
N2
N3
N1
N2
N1
N3
Figure 3. Plots showing the hydrogen bonding motifs – tetramer in 4ad (left) and chain in 3a (right)
While these four types of hydrogen bonding involve hydrogen bonding between N atoms of the pyrazole
rings and are, therefore, potentially available for any pyrazole, the other two types are unique to
cyanopyrazoles, as they involve the protonated pyrazole N as hydrogen-bond donor and the cyano N
atom as hydrogen-bond acceptor. Two different manifestations of this interaction are seen. In 3b and
3e, the hydrogen-bonded chains run along the crystallographic a-axis, with one pyrazole engaging in a
hydrogen-bonding interaction with a translationally related molecule (Figure 4, top). Thus, the linear
chain contains molecules which are all oriented in the same direction. In 4ac, the hydrogen-bonded
pyrazoles are related by the n-glide, resulting in a linear chain (Figure 4, bottom) in which the
orientation of the molecules alternates.

Br1
N2
N3
N1
N3
N1
N2
Figure 4. Plots showing the pyrazole-cyano hydrogen bonding motifs – 3b (top) and 4ac (bottom)
Cyanoscorpionate syntheses
The synthesis of polypyrazolylborates generally involves the reaction of the appropriate pyrazole with an
alkali metal borohydride. The initial synthesis of KTp was carried out without solvent, simply by heating
a mixture of the solid pyrazole and KBH4 above the melting point of the pyrazole. This melt method has
been successfully used to synthesize other scorpionates, as well, including our previous reports of
KBpR,4CN and KTpR,4CN ligands with R = phenyl and t-butyl. However, synthesis of some more highly
substituted scorpionates was reported to be more efficient when carried out in a high-boiling solvent, as
first demonstrated by Trofimenko with the use of dimethylacetamide for the synthesis of KBpR (R = Ph, t-
Bu) and anisole for conversion of the KBpR compounds to the corresponding KTpR compounds. [4]
Eichhorn and Armstrong reported a modification of this procedure for KTpPh in which the entire
synthesis was carried out in anisole over a period of two days. [38] Ruman, et al., reported the use of
tetradecane as a solvent for the synthesis of scorpionate ligands containing mixtures of the 3,5-
dimethyl- and 3,5-diphenyl-pyrazoles, indicating better control of the reactions using this solvent. [39]
We have found that the use of tetradecane as a solvent improved the yields for the synthesis of both
KTpPh,4CN and KTpt-Bu,4CN and also improves the synthesis of KTpPh, producing a 78% yield in 2-3 hours.
Tetradecane provides an excellent medium for the synthesis of scorpionate ligands with trisubstituted
cyanopyrazoles. The relative insolubility of both reactants and products at room temperature aids in the
isolation and purification of the resulting scorpionates. Four new scorpionates have been synthesized by
this method, KTpPh,Me,4CN, KTpPh,Br,4CN, KTpt-Bu,i-Pr,4CN, and KBpt-Bu,Me,4CN. These have been characterized by IR
and mass spectrometry, and the last has been characterized by X-ray crystallography. Two other new

scorpionates with trisubstituted cyanopyrazoles, Tpt-Bu,Ph,4CN and Tpt-Bu,Br,4CN, have been synthesized by
the traditional melt method and have been characterized by X-ray crystallography.
Table 3. Data Collection and Structure Solution Parameters for 5 - 8
Compound
formula
fw
temp, K
color
habit
crystal system
space group
dimen, mm
min
mid
max
5ba
6b
7bc
8
C42H43BKN9·C4H8O
795.86
150
white
block
C24H28BBr3KN9
732.19
150
lt. yellow
block
C18H26BKN6
376.36
150
lt. yellow
block
C46H76 B2N16Ni
933.55
150
lt. yellow
needle
monoclinic
P21/c
monoclinic
P21/c
monoclinic
Pc
monoclinic
P21/n
0.288
0.400
0.448
0.492
0.502
0.588
0.485
0.537
0.651
0.278
0.370
0.416
a, Å
b, Å
c, Å
α, deg
9.982(3)
29.005(9)
16.241(5)
90
9.894(3)
9.787(3)
19.293(7)
90
10.2660(19)
17.614(3)
16.026(3)
90
11.663(4)
24.069(9)
20.663(8)
90
β, deg
γ, deg
103.962(19)
90
4563(2)
4
1.158
92.742(16)
90
1866(1)
2
1.303
90.320(11)
90
2867.4(9)
4
0.872
105.50(2)
90
5590(3)
4
1.109
V, Å3
Z
ρcalc, g cm-3
μ, mm-1
unique refls (Rint)
0.160
10154 (0.1859)
3.379
0.195
0.393
7725 (0.0518)
5766
353
0.0436, 0.1176
0.975
6404 (0.0937)
3200
249
0.0984, 0.2944
1.037
5810 (0.2366)
2553
602
0.0895, 0.2042
1.015
obs refls, I>2σ(I) 3576
parameters
R, Rw
gof
532
0.0870, 0.2217
0.901
Tmax, Tmin
ρmax, ρmin, e Å-3
0.7455, 0.6590
0.57/-0.31
0.3655, 0.2563
0.54/-0.38
0.7455, 0.6741
0.46/-0.34
0.0842, 0.0592
0.30/-0.41
Cyanoscorpionate structures
All three of the potassium cyanoscorpionate structures are polymeric due to binding of the K+ ion to the
pyrazole N atoms of one scorpionate and to the cyano N atoms of other scorpionates. KTpt-Bu,Ph,4CN (5ba)
crystallizes on a general position in the monoclinic space group P21/c. A thermal ellipsoid plot is shown
in Figure 5. X-ray data collection and structure solution parameters are given in Table 3 and selected
bond distances and angles are in Table 4. The K+ ion is bound to the three pyrazole N atoms of the Tp
ligand with K-N bond distances of 2.835 – 2.903 Å. The K+ ion has a pseudo-octahedral geometry, with
additional bonding to cyano N atoms from two other Tp molecules (K-N bond distances 2.806 and 2.886
Å) and a THF molecule (K-O 3.217 Å). The t-butyl groups on all three pyrazoles are in the 3-position,
pointing towards the coordinated K. The phenyl rings in the 5-position of the pyrazole rings form a
pocket around the B-H bond of the Tp ligand and have dihedral angles with respect to their respective
pyrazole rings of 47.8, 54.6, and 63.8°. Two of the pyrazole rings are rotated about the B-N bond such

that the torsional angles H-B-N-N are on the order of 145°; the third pyrazole ring, has a torsional angle
of 165° (much closer to the ideal value of 180°).
Table 4. Selected bond distances (Å) and angles (°) for 5ba
K-N (pyrazole)
K-N (cyano)
K-O
B-N
N-B-N
2.908(4)
2.817(5)
3.221(9)
1.545(6)
109.8(3)
120.9(3)
54.34
2.843(3)
2.886(5)
2.840(3)
1.549(6)
112.0(3)
121.5(3)
48.09
1.563(6)
112.9(3)
123.2(3)
63.72
B-N-N
Pz/Ph dihedral
Br2
B1
Br1
Br3
B1
N5
N2
K1
N2
K1
N5
N8
N8
N9
N6
O1
N3
N6
N9
Figure 5. Plots showing the 50% thermal ellipsoids for 5ba and 6b. H atoms except for B-H, omitted for
clarity.
KTpt-Bu,Br,4CN (6b) crystallizes on a general position in the monoclinic space group Pc. A thermal ellipsoid
plot is shown in Figure 5. X-ray data collection and structure solution parameters are given in Table 3
and selected bond distances and angles are in Table 5. Unlike KTpt-Bu,Ph,4CN, this molecule crystallized
without any coordinated solvent molecules (a solvent mask was used in structure refinement), so the
coordination environment of the K+ ion consists of the three pyrazole rings of the Tp ligand and three
cyano N atoms from adjacent Tp ligands. Again the t-butyl substituents are in the 3-position of the
pyrazole rings, with the Br substituents occupying the 5-positions surrounding the B-H bond.
Table 5. Selected bond distances (Å) and angles (°) for 6b
K-N (pyrazole)
K-N (cyano)
B-N
C-Br
N-B-N
2.991(4)
2.827(6)
1.552(7)
1.868(6)
108.9(4)
124.5(4)
2.925(4)
2.829(6)
1.540(7)
1.849(6)
109.8(4)
122.7(4)
2.885(4)
2.865(6)
1.541(7)
1.847(6)
112.4(4)
123.1(4)
B-N-N

KBpt-Bu,Me,4CN (7bc) crystallizes in the monoclinic space group P21/n. Thermal ellipsoid diagrams of 7bc are
shown in Figure 6 and selected bond distances and angles are given in Table 6. The K+ ions exist in pairs,
related by a center of symmetry, with each K bound to both pyrazole atoms of one Bp ligand, and one of
the pyrazoles also bound to the second K ion. Thus each Bp ligand has one pyrazole which binds only to
one K ion and one which bridges between two K ions. The cyano N of each pyrazole also binds to a K ion,
resulting in a two-dimensional network.
Table 6. Selected bond distances (Å) and angles (°) for 7bc
K1-N2
K1-N5
K1’-N1
K1’-N2
K…K
2.880(3)
2.836(3)
3.218(3)
3.283(3)
4.210(1)
K1-N3
K1-N6
B1-N1
B1-N4
K1-H1A
2.782(4)
2.722(4)
1.546(5)
1.562(5)
2.77(5)
N2-K1-N5
71.45(9)
N5-K1-N1’ 142.32(8)
N5-K1-N2’ 117.92(8)
N5-K1-N3’ 86.8(1)
N5-K1-N6’ 123.1(1)
N5-K-H1A
61(1)
N4
B1
N1
N2
N5
K1
N3
N6
Figure 6. Plots showing the 50% thermal ellipsoids for 7bc. (left) dimeric core showing K, N, and B atoms;
(right) two bridged dimeric units. H atoms, except for B-H, omitted for clarity.
[Ni(cyclam)](Bpt-Bu,Me,CN
)
2
A very common paradigm for scorpionates is the sandwich complex, in which two Tp ligands coordinate
to a transition metal ion via the three available pyrazole N atoms on each Tp ligand. Similar Bp2M
complexes have been reported with Bp ligands. With cyanoscorpionate ligands, we have reported these
types of complexes, [17,18] as well as “inverted sandwich” complexes, [19] in which two Tp ligands
coordinate to the metal only through the cyano N atom of one pyrazole, with the metal ion’s octahedral
coordination sphere completed by four other neutral donors. This type of structure was found to be
especially prevalent with Tpt-Bu,4CN, due to the bulkiness of the t-butyl substituent, and included [(Tpt-
Bu,4CN)2Ni(cyclam)]. With the Bpt-Bu,Me,4CN ligand it seemed that a similar complex could be isolated.
Reaction of two equivalents of KBpt-Bu,Me,4CN with [Ni(cyclam)](ClO4)2 resulted in a complex, 8, with the
expected stoichiometry of two Bp ligands per Ni(cyclam) moiety, but X-ray crystallographic
characterization of the complex showed that the Bp ligands were not actually coordinated to the Ni ion.

A thermal-ellipsoid diagram of [Ni(cyclam)](Bpt-Bu,Me,CN)2 (8) is shown in Figure 7, with data collection and
structure solution parameters in Table 3 and selected bond distances and angles in Table 7. The complex
crystallizes on a general position in the monoclinic space group P21/c. The coordination geometry
around the Ni ion is square-planar, consisting just of the four amine N atoms of the cyclam ligand. The
two Bp ions are situated on either side of the Ni(cyclam) plane, but the cyano groups are directed away
from the Ni complex and one B-H group from each ligand is directed towards the Ni. There may be some
interaction between the B-H groups and the Ni ion, with Ni…H distances ranging from 2.440 to 2.539 Å.
For comparison, an agostic interaction between the B-H group and Ni in TpPh,4CNBpPh,4CNNi showed Ni…H
distances of 2.214 and 2.245 Å. [21] In addition, H-bonding interactions exist between cyclam N-H
groups and the free pyrazole N atoms.
Table 7. Selected bond distances (Å) and angles (°) for 8
Ni-N(cy)
N(cy) … N(pz)
B … Ni
N(cy)-H…N(pz) 162.3
B-H…Ni 164.5
1.946(7)
3.15(1)
3.42(1)
1.951(8)
3.22(1)
3.42(1)
170.1
1.966(8)
3.13(1)
1.964(8)
3.10(1)
172.8
164.3
167.6
N4
N1
N10
N7
Figure 7. Plot showing the 50% thermal ellipsoids for 8. H atoms omitted for clarity, except B-H and N-H.
Conclusion
New routes have yielded cyanopyrazoles with a wide range of substituents, including 4-cyanopyrazoles
with symmetric and asymmetric substitution at the 3- and 5-positions of the pyrazole ring. Tetradecane
has been shown to be a useful medium for the synthesis of cyanoscorpionates; seven new
cyanoscorpionates with trisubstituted pyrazoles have been isolated and three crystallographically
characterized. An unexpected species in which the Bp molecule serves only as a counterion to the
Ni(cyclam) complex has been characterized. The new routes to cyanopyrazoles and the new
trisubstituted cyanopyrazoles open up the possibilities to scorpionate ligands with an even wider range
of steric and electronic properties.

5. Supplementary Materials
X-ray crystallographic data for 2 – 8 have been deposited with the Cambridge Crystallographic Data
center. CCDC 1489320-1489335 contain the supplementary crystallographic data for this paper. The
data can be obtained free of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/structures.
6. Acknowledgements
We thank Mr. Ali Jehan, Mr. Matthew Baird, and Dr. Alexandre Shvartsburg for mass spectrometric
analyses. This research did not receive any specific grant from funding agencies in the public,
commercial, or not-for-profit sectors.
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Graphical abstract
Synopsis
New syntheses are reported for pyrazoles bearing a cyano substituent at the 4-position, alkyl or aryl
substituents at the 3-position, and alkyl, aryl, or bromo substituents at the 5-position. New scorpionate
ligands are reported with some of the tri-substituted cyanopyrazoles.