Facile syntheses and- structures of new metal-maleonitrilediselenolates [K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)(Se6)], [K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)<s

Article abstract of DOI:10.1021/ic9901719

Facile syntheses of [K([2.2.2]-cryptand)]₃Ag(Se₂C₂(CN)₂)(Se₆)] (1) and [K([2.2.2]-cryptand)]₂-[Ni(Se₂C₂(CN)₂)₂] (2) are achieved through reaction

Full text of DOI:10.1021/ic9901719

1046
Inorg. Chem. 2000, 39, 1046-1048
X-ray Structure Determinations. Intensity data were collected at
Facile Syntheses and Structures of New
Metal-Maleonitrilediselenolates
[K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)(Se6)],
[K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)2], and
Ni(dppp)(Se2C2(CN)2)
-120 °C on a Bruker AXS SMART-1000 diffractometer equipped with
a CCD area detector. Graphite monochromatized Mo KR radiation was
used. Structures were solved by means of direct methods and were
refined on F2 with the use of full-matrix least-squares techniques.11
The crystallographic results are summarized in Table 1. Further details
are provided in Supporting Information.
Synthesis of [K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)(Se6)] (1). A
mixture of 5.6 mg (0.1 mmol) of KNH2, 40 mg (0.2 mmol) of AgBF4,
63 mg (0.4 mmol) of K2Se, 158 mg (2 mmol) of Se, and 340 mg (0.9
mmol) of [2.2.2]-cryptand was dissolved in 10 mL of acetonitrile; a
green solution resulted. The reaction flask was wrapped in aluminum
foil to keep out light. After 20 h the solution was filtered and the green
filtrate was cooled to 4 °C and kept there for 1-3 h. The filtrate was
layered with 10 mL of diethyl ether/toluene (10:1), and dark red crystals
of 1 were isolated after 48 h. Yield: 0.164 g (40% based on Ag).
Reaction with AgCl in lieu of AgBF4 yields the same product.
Synthesis of [K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)2] (2). For
method 1, 15 mg (7.2 µmol) of 1 was dissolved in 5 mL of dmf to
afford a brown solution. NiCl2 (0.4 mg, 3.2 µmol) was suspended
in 2 mL of dmf. After 1 h the NiCl2 suspension was added to the
solution of [K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)(Se6)] (1) to give a
lighter brown solution. After 4 h this solution was filtered to remove
Se, and the resultant orange filtrate was reduced 70% in volume in
vacuo. The resultant solution was layered with 7 mL of diethyl ether/
toluene (10:1), and red plates of 2 were isolated after 24 h. Yield: 5
mg (50% on 1)
For method 2, a mixture of 11 mg (0.2 mmol) of KNH2, 63 mg (0.4
mmol) of K2Se, 158 mg of Se (2 mmol), and 340 mg (0.9 mmol) of
[2.2.2]-cryptand was dissolved in 10 mL of acetonitrile to give a green
solution. Ni(dppp)Cl2 (55 mg, 0.1 mmol) was dissolved in 5 mL of
acetonitrile. After 1 h the Ni(dppp)Cl2 solution was added to the first
solution; a green solution resulted. After 14 h the solution was filtered
and the green filtrate was cooled to 4 °C for 1-3 h. The filtrate was
layered with 11 mL of diethyl ether/toluene (10:1), and dark red crystals
of 2 were isolated after 48 h. Yield: 0.148 g (54% on Ni). IR (KBr)
(CN region, cm-1): 2187. UV/vis (dmf (nm, ꢀ)): 281 (6695), 331
(5237), 399 (2376), 495 (1264). Anal. Calcd for C44H72K2N8NiO12Se4:
C, 38.92; H, 5.34; N, 8.25. Found: C, 38.42; H, 5.08; N, 7.75. 31P
NMR spectrum of the reaction mixture of method 2 in CH3CN spiked
with CD3CN: -18.3 ppm.
Synthesis of Ni(dppp)(Se2C2(CN)2) (3). An amount of 10 mg (4.8
µmol) of [K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)(Se6)] (1) was dissolved
in 5 mL of dmf to give a brown solution. An orange solution was
obtained when Ni(dppp)Cl2 (9 mg, 18.0 µmol) was dissolved in 2 mL
of dmf. After being stirred for 1 h, the Ni(dppp)Cl2 solution was added
to the solution of 1. After 4 h the solution was filtered to remove Se
and the resultant filtrate was reduced to dryness in vacuo. The residue
was redissolved in a minimum of dmf (∼2 mL) and layered with 5
mL of diethyl ether/toluene (10:1). Orange needles were isolated after
48 h. Yield: 0.15 mg (4% on 1). Mp, 119 °C. IR (KBr) (CN region,
cm-1): 2204. UV/vis (CH2Cl2 (nm, ꢀ)): 271 (5700), 285 (6734), 301
(5211), 331 (1764), 392 (638), 578 (82). 1H NMR (CD2Cl2, ppm, 300
MHz) δ 2.41 (dt, 4H, CH2), 2.79 (m, 2H, CH2), 7.10 (dd, 8H, Ar-H),
7.46(d, 8H, Ar-H), 7.76(t, 4H, Ar-H). ESI MS(+): 678.9 (m/z, (Ni-
(dppp)(Se2C2CN))+). EDS shows consistent ratios of 2:1:2 for P/Ni/Se
for C31H26N2NiP2Se2 (3).
Craig C. McLauchlan and James A. Ibers*
Department of Chemistry, Northwestern University, 2145
Sheridan Road, Evanston, Illinois 60208-3113
ReceiVed February 10, 1999
Introduction
Metal complexes containing the maleonitriledithiolate (mnt,
[S2C2(CN)2)]2-) ligand have been extensively studied. The
literature abounds with uses of metal-mnt complexes for charge
transfer, for charge storage, and as molecular metals.1-3 Despite
the abundance of metal-mnt complexes and the extensive
literature on [Se2C2R2]2- species,4-8 complexes of the selenium
analogue of mnt, maleonitrilediselenolate (mns, [Se2C2(CN)2]2-
)
were unknown until recently. The first metal-mns complex was
isolated as [NBu4]2[Ni(mns)2],9 although unsuccessful earlier
efforts are reported.4 The [Ni(mns)2]2- species was isolated by
a difficult synthesis involving carbon diselenide and dicy-
anoacetylene.9 Recently, we reported the serendipitous syntheses
of two metal-mns complexes, [K([2.2.2]-cryptand)]3[Sb(mns)2]
and [K([2.2.2]-cryptand)]3[Ag(mns)(Se6)] (1).10 We report here
an improved synthesis of complex 1 and the syntheses of
[K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)2] (2) and Ni(dppp)(Se2C2-
(CN)2) (3), where dppp ) 1,3-bis(diphenylphosphino)propane.
Experimental Section
General Procedures. Infrared spectra were collected on a Bio-Rad
Digilab FTS-60 FTIR spectrometer for samples as KBr mulls. 1H and
31P NMR spectra were collected on a Gemini 300 instrument; 31P NMR
spectra were referenced to neat H3PO4. K2Se was prepared stoichio-
metrically from the elements in liquid ammonia. KNH2 was prepared
by reaction of KH with liquid ammonia. Ni(dppp)Cl2 (97%), Se
(99.9%), AgBF4 (98%), and [2.2.2]-cryptand ()4,7,13,16,21,24-hexaoxa-
1,10-diazabicyclo[8.8.8]hexacosane) (98%) were purchased commer-
cially and were used without further purification. N,N-dimethylforma-
mide (dmf) was dried over 4 Å sieves and degassed prior to use.
Electrospray mass spectroscopic analyses were performed on a Mi-
croscan Quattro II instrument operated in a positive ion mode. Energy
dispersive spectroscopy was performed on an EDAX equipped Hitachi
S-4500 field emission scanning electron microscope. Microanalyses
were performed by Oneida Research Services, Whitesboro, NY.
(1) Ba¨hr, G.; Schleitzer, G. Chem. Ber. 1955, 88, 1771-1777.
(2) McCleverty, J. A. Prog. Inorg. Chem. 1968, 10, 49-221.
(3) Clemenson, P. I. Coord. Chem. ReV. 1990, 106, 171-203.
(4) Davison, A.; Shawl, E. T. Inorg. Chem. 1970, 9, 1820-1825.
(5) Nigrey, P. J. Synth. React. Inorg. Met.-Org. Chem. 1986, 16, 1351-
1355.
Results and Discussion
(6) Olk, B.; Olk, R.-M.; Sieler, J.; Hoyer, E. Synth. Met. 1991, 41-43,
2585-2588.
Previously, we reported that addition of [Ir(cod)Cl]2 (cod )
1,5-cyclooctadiene) to AgBF4, K2Se, Se, and [2.2.2]-cryptand
in liquid ammonia followed by evaporation of the ammonia and
dissolution of the residue in acetonitrile yielded [K([2.2.2]-
(7) Olk, R.-M.; Ro¨hr, A.; Olk, B.; Hoyer, E. Z. Chem. 1988, 8, 304-
305.
(8) Dietzsch, W.; Franke, A.; Hoyer, E.; Gruss, D.; Hummel, H.-U.; Otto,
P. Z. Anorg. Allg. Chem. 1992, 611, 81-84.
(9) Morgado, J.; Santos, I. C.; Duarte, M. T.; Alca´cer, L.; Almeida, M. J.
Chem. Soc., Chem. Commun. 1996, 1837-1838.
(10) Smith, D. M.; Albrecht-Schmitt, T. E.; Ibers, J. A. Angew. Chem.,
Int. Ed. Engl. 1998, 37, 1089-1091.
(11) Sheldrick, G. M. SHELXTL DOS/Windows/NT, version 5.10; Bruker
Analytical X-Ray Instruments, Inc.: Madison, WI, 1997.
10.1021/ic9901719 CCC: $19.00 © 2000 American Chemical Society
Published on Web 02/02/2000

Notes
Inorganic Chemistry, Vol. 39, No. 5, 2000 1047
Table 1. Crystallographic Data for
[K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)2] (2) and
Ni(dppp)(Se2C2(CN)2) (3)
compound
2
3
chemical formula
fw
a, Å
b, Å
C44H72K2N8NiO12Se4
1357.85
12.220(1)
15.860(2)
15.306(1)
107.64(2)
2827(1)
P21/c
C31H26N2NiP2Se2
705.11
12.400(1)
15.407(1)
14.451(1)
90
2952(1)
Pnma
4
c, Å
â, deg
V, Å3
space group
Z
2
λ, Å
0.710 73
1595
313
153(2)
0.044
0.710 73
1587
326
153(2)
0.026
0.059
F
calc, g cm-3
µ, cm-1
T, K
R1(F)a
wR2(Fo )b
0.081
2
2
2
a R1(F) ) ∑(|Fo| - |Fc|)/∑|Fo|. b wR2(Fo ) ) [∑[w(Fo - Fc2)2]/
4
2
2
2
2
∑wFo ]1/2; w-1 ) σ2(Fo ) + (0.03Fo )2 for Fo > 0; w-1 ) σ2(Fo ) for
Figure 2. Structure of 3, Ni(dppp)(Se2C2(CN)2). Hydrogen atoms are
drawn as arbitrarily small circles. The molecule has a crystallographi-
cally imposed mirror plane.
2
Fo ) 0.
Table 2. Average Bond Distances (Å) and Bond Angles (deg) in
Metal-mns Complexes
Nia
Ni (2)b
Ni (3)b
Sbc
Ag (1)c
Bond Distances
M-Se
Se-C
CdC
C-CN
C-N
2.285
1.876
1.357
1.422
not
2.292(1)
2.285(1)
1.884(2)
1.349(4)
1.433(3)
1.146(3)
2.654(2)
2.567(4)
1.853(2)
1.38(3)
1.43(3)
1.116(3)
1.874(4)
1.350(5)
1.439(6)
1.136(5)
1.866(17)
1.358(20)
1.439(24)
1.138(20)
Figure 1. Structure of the anion in 2, [Ni(Se2C2(CN)2)2]2-. Here and
in Figure 2 displacement ellipsoids are drawn at the 50% probability
level.
reported
Bond Angles
92.08(2)
101.34(12) 102.86(6) 96.71(48)
121.89(31) 118.18(14) 128.28(1.22) 128.05(1.85)
121.33(38) 120.64(11) 117.59(1.48) 114.11(2.22)
178.87(51) 178.20(23) 177.08(1.90) 175.92(3.15)
Se-M-Se 92.8
M-Se-C 102.1
Se-CdC 121.4
CdC-CN 121.4
C-C-N 178.3
93.17(2)
87.81(7)
91.44(13)
97.54(8)
cryptand)]3[Ag(Se2C2(CN)2)(Se6)] (1).10 A more direct synthesis
has been devised in which a mixture of AgBF4, K2Se, Se,
[2.2.2]-cryptand, and KNH2 in acetonitrile affords complex 1.
This route leads to higher yields (40% vs 16%) and avoids the
use of both the relatively costly Ir starting material and of liquid
ammonia as a solvent.
a [Ni(mns)2]2-; ref 9. [Ni(mns)2]2- and Ni(dppp)(mns); this work.
b
c [Sb(mns)2]3- and [Ag(mns)(Se6)]3-; ref 10.
Ni(dppp)(Se2C2(CN)2) (3) (Figure 2) has a square-planar Ni-
(II) center coordinated by the bidentate dppp ligand and a single
mns ligand. Table 2 shows average bond lengths within the mns
ligand for the known metal-mns complexes.
1. MeCN
4′′{K}2Se4′′ + {Κ}[ΝΗ2] + 2AgBF4 2. Et O/toluene8
2
{K} ) [K([2.2.2]-cryptand)]
{K}3[Ag(mns)(Se6)] (1)
In the reaction to form mns, the most likely CN source is
acetonitrile. In our original report10 of the synthesis of [K([2.2.2]-
cryptand)]3[Sb(mns)2] and [K([2.2.2]-cryptand)]3[Ag(mns)(Se6)]
(1), we proposed that K or [Ir(cod)Cl]2 reacts with ammonia to
produce a strong basesKNH2 or an Ir species,13,14 respectively.
The base likely deprotonates acetonitrile to form a -CH2CN
species, since [As(Se)3(CH2CN)]3- is formed under similar
reaction conditions.10 This proposal is supported here, since the
formation of complex 1 has been achieved in the absence of an
Ir source and liquid ammonia by introducing the strong base
KNH2 into an acetonitrile solution. The present results provide
no insight into what transpires after the proposed deprotonation
of acetonitrile. The -CH2CN species may couple head to head
and be further deprotonated. The -CH2CN may react with Se
to form an unstable and reactive selenoaldehyde.15,16 Alterna-
The addition of NiCl2 to complex 1 in dmf affords red crystals
of [K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)2] (2) and gray Se.
Complex 2 can also be formed under conditions similar to those
used to make complex 1. Complex 2 can be made directly in
54% yield by reaction of KNH2, K2Se, Se, and [2.2.2]-cryptand
with Ni(dppp)Cl2 in acetonitrile. In this reaction the mns ligand
displaces the chloro and dppp ligands. The presence of free dppp
in solution was confirmed by a 31P NMR spectrum. But the
addition of Ni(dppp)Cl2 to complex 1 in dmf affords orange
needles of Ni(dppp)(Se2C2(CN)2) (3), [K([2.2.2]-cryptand)]2-
[NiCl4], and gray Se.
[K([2.2.2]-cryptand)]2[Ni(Se2C2(CN)2)2] (2) possesses well-
separated anions and cations. The [Ni(mns)]2- anion of 2 is
depicted in Figure 1. This anion, which is similar to that in
[NBu4]2[Ni(mns)2],9 comprises a square-planar Ni center coor-
dinated by two mns ligands. Since a square-planar environment
is that expected for Ni(II) and since the overall charge on the
anion is -2, we assign a formal charge of -2 to the mns ligand.
The “noninnocence” of mnt, however, is well documented,2,3,12
and mns is expected to behave similarly. The molecule
(12) Fourmigue´, M.; Domercq, B. Actual. Chim. 1998, 11-12, 9-13.
(13) Casalnuovo, A. L.; Calabrese, J. C.; Milstein, D. Inorg. Chem. 1987,
26, 973-976.
(14) Koelliker, R.; Milstein, D. Angew. Chem., Int. Ed. Engl. 1991, 30,
707-709.
(15) Meinke, P. T.; Krafft, G. A. Tetrahedron Lett. 1987, 28, 5121-5124.

1048 Inorganic Chemistry, Vol. 39, No. 5, 2000
Additions and Corrections
tively, -CH2CN may react with Se to afford a species that
dimerizes in solution to form the mns ligand, similar to the
reaction by which the sodium salt of the mnt ligand is formed.1,17
Although complex 1 is not the ideal synthon, its reaction with
metal chlorides and their derivatives is a viable route to other
metal-mns complexes, as illustrated here. For example, the
reaction of 1 with a Pd source affords the Pd(mns)(Se4)2-
anion.18 With the use of such a facile reaction, a variety of new
metal-mns complexes may be synthesized and their physical
properties systematically studied.
Acknowledgment. This research was supported by the
National Science Foundation (Grant CHE-9819385). The Quat-
tro II spectrometer was provided by the National Institutes of
Health, Grant S10 RR11320.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of [K([2.2.2]-cryptand)]2-
[Ni(Se2C2(CN)2)2] (2) and Ni(dppp)(Se2C2(CN)2) (3). This material is
available free of charge via the Internet at http://pubs.acs.org.
IC9901719
(16) Kirby, G. W.; Trethewey, A. N. J. Chem. Soc., Perkin Trans. 1 1988,
1913-1922.
(17) Davison, A.; Holm, R. H. Inorg. Synth. 1967, 10, 8-26.
(18) McLauchlan, C. C.; Ibers, J. A. Unpublished results.
Ad d ition s a n d Cor r ection s
2000, Volume 39
Zenghe Liu and Fred C. Anson*: Electrochemical Prop-
erties of Vanadium(III,IV,V)-Salen Complexes in Acetonitrile.
Four-Electron Reduction of O2 by V(III)-Salen.
Page 280. A paragraph describing the available Supporting
Information was omitted. The paragraph is provided below.
Supporting Information Available: Three figures showing 51V
NMR, ESR, and UV-vis spectra of various vanadium-salen complexes
and kinetic plots for the reaction of O2 with VIII(salen)+. This material
is available free of charge via the Internet at http://pubs.acs.org.
IC992000+
10.1021/ic992000+
Published on Web 03/06/2000