Metal cyanide ions Mx(CN)y]+,- in the gas phase: M = Fe, Co, Ni, Zn, Cd, Hg, Fe + Ag, Co + Ag

Article abstract of DOI:10.1021/ic011227d

The generation of metal cyanide ions in the gas phase by laser ablation of M(CN)₂ (M = Co, Ni, Zn, Cd, Hg), Fe^III[Fe^III(CN)₆]·xH₂O, Ag₃[M(CN)₆] (M = Fe, Co), and Ag₂[F

Full text of DOI:10.1021/ic011227d

Inorg. Chem. 2002, 41, 3560−3569
+,-
Metal Cyanide Ions M (CN) ] in the Gas Phase: M ) Fe, Co, Ni, Zn,
x
y
Cd, Hg, Fe + Ag, Co + Ag
,1
Ian G. Dance,* Philip A. W. Dean,* Keith J. Fisher, and Hugh H. Harris
School of Chemistry, UniVersity of New South Wales, Sydney NSW 2052, Australia
Received November 30, 2001
The generation of metal cyanide ions in the gas phase by laser ablation of M(CN)
2
(M ) Co, Ni, Zn, Cd, Hg),
III
III
Fe [Fe (CN)
6
]‚xH
2
O, Ag
3
[M(CN)
6
](M) Fe, Co), and Ag
2 5
[Fe(CN) (NO)] has been investigated using Fourier transform
ion cyclotron resonance mass spectrometry. Irradiation of Zn(CN)
2
and Cd(CN)
2
produced extensive series of
(CN)2n+1]- (1 e n e 27) and [Cd
(CN)2n+1] (n ) 1, 2, 8−27, and possibly 29, 30). Cations Hg(CN)
-
+
anions, [Zn
and [Hg (CN)
Fe (CN) ]‚xH
Fe(CN) ] is ablated, [AgFe(CN)
The additional heterometallic complexes [AgFe
observed on ablation of Ag [Fe(CN) (NO)]. Homoleptic anions [Co
] are formed when anhydrous Co(CN)
n
n
+
-
III
2
x
] (x ) 1−3), and anions [Hg(CN)
x
] (x ) 2, 3), are produced from Hg(CN)
2
. Irradiation of Fe -
(CN)
]-. When Ag
5
] are observed together with homoleptic anions of Fe and Ag.
III
-
-
-
-
[
[
6
2
O gives the anions [Fe(CN)
2
] , [Fe(CN)
3
] , [Fe
2
(CN)
3
] , [Fe
2
(CN)
4
] , and [Fe
2
5
3
-
]- and [Ag
Fe(CN)
(CN)
-
6
4
2
]-, [AgFe
] , [Ag
-
Fe
(CN)
]-, and [Ag
(CN)n+2]- (n ) 1−3),
[Co(CN) ] yields
(CN)n+1] (n ) 1−3), [Co
3 6
Fe(CN)
]- are
2
6
3
(CN)
8
2
2
7
-
2
5
n
(CN)n+1] (n ) 1−3), [Co
n
-
-
[
Co
2
(CN)
4
] , and [Co
3
(CN)
5
2
is the target. Ablation of Ag
3
6
+
+
-
-
cations [Ag
n
(CN)n-1] (n ) 1−4) and [Ag
n
Co(CN)
n
] (n ) 1, 2) and anions [Ag
n
n
(CN)n-1]
-
-
+
(n ) 1, 2), [Ag
n
Co(CN)n+2] (n ) 1, 2), and [Ag
n
Co(CN)n+3] (n ) 0−2). The Ni(I) species [Ni
n
(CN)n-1] (n ) 1−4)
-
-
n
and [Ni (CN)n+1] (n ) 1−3) are produced when anhydrous Ni(CN)
2
is irradiated. In all cases, CN and polyatomic
-
carbon nitride ions C
x
N
y
are formed concurrently. On the basis of density functional calculations, probable structures
are proposed for most of the newly observed species. General structural features are low coordination numbers,
10
regular trigonal coordination stereochemistry for d metals but distorted trigonal stereochemistry for transition metals,
the occurrence of M−CN−M and M(−CN−) M bridges, addition of AgCN to terminal CN ligands, and the occurrence
of high spin ground states for linear [M
(CN)n+1]- complexes of Co and Ni.
2
n
Introduction
ablation of zinc and cadmium cyanides M(CN)
2
yielded
-
2
extended series of ions [M (CN)2n+1] (up to n ) 27), for
n
In a previous paper, we reported that laser ablation (LA)
of MCN (M ) Cu, Ag) yielded the gaseous ions [M (CN)n-1]
n
and [M (CN)n+1] , characterized by Fourier transform ion
n
cyclotron resonance mass spectrometry (FTICR MS). Ge-
ometry optimizations using density functional theory showed
that the most stable structures for the Cu(I) ions are linear
alternations of Cu and CN, even at the highest values of n
observed (n ) 6 for [Cu
The occurrence of these very long straight molecules, one
+
which density functional and force-field calculations indi-
cated the occurrence of helical structures formed by almost
-
linear M-(µ-CN)-M linkages of three-coordinate (µ-CN)
2
-
3
MCN units.
Following the results for gas-phase cyano complexes of
Cu(I), Ag(I), Zn(II), and Cd(II), and the tendency of CN
to form linear bridges, we expected that further binary
metal-cyanide clusters and structures could be generated
-
+
-
n
n
(CN)n-1] , n ) 5 for [Cu (CN)n+1] ).
-
in the gas phase. Intriguing polycyanometalate molecular
atom thick, is consistent with the propensity of CN to
participate in linear M-CN-M bridging, as opposed to
M-C(N)-M bridging or other bridging modes. Laser
4
clusters such as [Mn{Mn(MeOH)
3
}
8
(µ-CN)30{Mo(CN)
, and Cr Ni (CN)24 and Cr10Ni
CN)42 clusters in crystals have been reported recently.
3 6
} ],
12+ 5
[
(Me
3
tacn)
8
Cr
8
Ni
6
(CN)24
]
8
5
9
-
6
(
*
To whom correspondence should be addressed. E-mail: i.dance@
unsw.edu.au (I.G.D.); pawdean@julian.uwo.ca (P.A.W.D.).
1) On leave from The University of Western Ontario, London, Ontario
N6A 5B7, Canada.
(3) Dance, I. G.; Dean, P. A. W.; Fisher, K. J. Angew. Chem., Int. Ed.
Engl. 1995, 34, 314-316.
(4) Larionova, J.; Gross, M.; Pilkington, M. J.; Andres, H.; Stoeckli-Evans,
H.; Gudel, H. U.; Decurtins, S. Angew. Chem., Int. Ed. 2000, 39,
1605-1609.
(
(
2) Dance, I. G.; Dean, P. A. W.; Fisher, K. J. Inorg. Chem. 1994, 33,
6261-6269.
3560 Inorganic Chemistry, Vol. 41, No. 13, 2002
10.1021/ic011227d CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/07/2002

Metal Cyanide Ions in the Gas Phase
several hours.7e The very fine deep green product was separated
by centrifugation, washed three times with water and twice with
EtOH, and then dried in vacuo.
Accordingly, we extended our ablation studies to include
the cyanides of mercury and of transition metals with
different oxidation states and coordination chemistry. We
present here a fuller account of our LA FTICR MS studies
The silver salts Ag
NO)] precipitated on mixing aqueous solutions of Ag(NO
the appropriate K [M(CN) ] or Na [Fe(CN) (NO)]‚2H O in a foil-
3
[M(CN)
6 2
] (M ) Fe, Co) and Ag [Fe(CN)
5
-
(
3
) and
of M(CN)
for M(CN)
Fe(CN)
is not well characterized.7 We have also investi-
gated mixed-metal cyanides in the gas phase, using solid
Ag [M(CN) ] (M ) Fe, Co), and Ag [Fe(CN) (NO)] as
precursors.
2
(M ) Zn or Cd) and new LA FTICR MS data
III
III
7a
3
6
2
5
2
2
(M ) Hg, Co, Ni), Fe [Fe (CN)
6
2
]‚xH O.
covered beaker. They were washed with water and then EtOH and
dried under vacuum.
LA FTICRMS. Sample preparation and the apparatus and
techniques used for the laser ablation and mass spectrometry have
been described previously in papers from these laboratories.2,10 The
a
2
3
6
2
5
Finally, we report calculations by density functional theory
of the possible structures of many of the ions that we observe,
and we compare what we have observed in the gas phase
with the known structural chemistry of cyanide complexes
of the various central elements in condensed phases. Many
crystalline cyanocomplexes have interesting structures and
magnetic properties.4-6,8
LA FTICR mass spectra of all of the cyanides were surveyed at
both 1064 and 532 nm using a Q-switched YAG laser. Power
3
-2
densities available were in the range 1.3-85 × 10 MW cm at
-
2
1
064 nm and 2.4-77 MW cm at 532 nm (assuming a typical
spot size of 0.2 mm diameter). Typically, nominal starting power
3
-2
levels in an experiment were 1.7 × 10 MW cm at 1064 nm and
-
2
1
1 MW cm at 532 nm, and the spectra were optimized in terms
of the number of species observed and the signal/noise (S/N) by
adjusting the laser power. Approximate actual power levels were
calculated using the average energy of the laser pulse, measured
with a joule-meter, and the actual size of the irradiated spot at the
end of the experiment, measured with a microscope. The same ions
were observed using both 1064 and 532 nm irradiation, except as
noted in Table 1.
An ion was considered observed if it occurred with S/N g 2
over several repetitions of the spectral measurement. For experi-
ments involving collision-induced dissociation (CID), the collision
Experimental Section
CAUTION! Metal cyanides and most cyanometalates are toxic
and should be handled and disposed of accordingly.
Materials. Sodium cyanide (Mallinckrodt), ZnSO
Chemicals), and Cd(NO ‚4H O (BDH) were analytical reagents
and were used as received, as were reagent-grade AgNO (Ajax
Chemicals), Ni(NO ‚6H O, CoSO ‚7H O, and K Fe(CN) (all
from M and B), Hg(CN) (BDH), and Na [Fe(CN) (NO)]‚2H O.
The literature method was used to prepare K [Co(CN)
4
2
‚7H O (Ajax
3
)
2
2
3
3
)
2
2
4
2
3
6
2
2
5
2
9
-
3
6
].
gas, Ar, (CCl was also used for the C N anions) was present at
4
x
y
Syntheses. Zinc cyanide was precipitated by stirring an aqueous
a pressure of 1 × 10-7 mbar. Ions for CID were selected and all
solution containing the stoichiometric quantity of NaCN into an
unwanted ions removed from the cell. The selected ions were
accelerated with an rf excitation pulse and allowed to have ∼1
collision (0.02-0.05 s) before observation of the product ions. The
short collision time was used to avoid secondary collisions and
also to reduce the possibility of ion rearrangement. Collision
energies given in the Results and Discussion sections are center-
of-mass collision energies giving ca. 50% dissociation.
7b
aqueous solution of ZnSO
Ni(CN) were prepared similarly from NaCN and the appropriate
metal nitrate.7 Hydrated Co(CN)
by using solutions that had been deoxygenated using a flow of N
4 2
‚7H O. Cadmium cyanide and hydrated
2
b,c
2
was synthesized similarly, but
2
-
7d
(
g).
Colorless Zn(CN)
washed three times with water and three times with acetone, and
then dried in vacuo. The very fine precipitate of hydrated Ni(CN)
2
2
and Cd(CN) were separated by filtration,
In general, the spectra from the initial laser shots were not
representative of those from the later shots, a common situation
during laser ablation studies.11 The laser hits one spot, and the
resulting surface modification presumably leads to the observed
spectral changes. The spectra that we show are representative of
those obtained from approximately the 5th laser shot through to
the 20th laser shot.
2
was separated by centrifugation, washed three times with water
and twice with EtOH, recentrifuging after each wash, and then dried
in vacuo. Yellow-brown anhydrous Ni(CN)
heating the hydrated material at 150 °C overnight.7 Pink-beige
hydrated Co(CN) was also separated by centrifugation. It was
washed three times with water, and the final slurry was converted
to deep blue anhydrous Co(CN) by slowly heating it to 250 °C
under a flow of N is very easily
(g).7d Anhydrous Co(CN)
rehydrated and was handled thereafter in a glovebag under N (g).
O was produced by heating an aqueous
and K Fe(CN) (3:1) at 90 °C in the dark for
2
was obtained by
c
2
Density Functional Calculations. Calculations were with the
program DMol3,12 using the double numeric basis sets12a including
2
2
2
polarization functions (basis set type DND). The calculations were
all-electron and were unrestricted for all species not having a well-
defined closed shell. Scalar relativistic corrections to the core
orbitals were included for the all-electron calculations for the
mercury species. Becke 88 exchange and Lee-Yang-Parr cor-
2
III
III
Fe [Fe (CN)
solution of FeCl
6
]‚xH
3
2
3
6
(
(
(
5) Berseth, P. A.; Sokol, J. J.; Shores, M. P.; Heinrich, J. L.; Long, J. R.
J. Am. Chem. Soc. 2000, 122, 9655-9662.
6) Sokol, J. L.; Shores, M. P.; Long, J. R. Angew. Chem., Int. Ed. 2001,
13
relation functionals were used throughout. The calculational
strategy involved geometry optimization for numerous postulated
40, 236-239.
7) Sharpe, A. G. The Chemistry of the Cyano Complexes of the Transition
Elements; Academic Press: London, 1976. (a) Page 103 ff and
references therein. (b) Page 287 ff. (c) Page 231 ff and references
therein. (d) Page 166 ff and references therein. (e) Page 123 ff and
references therein. (f) Page 103 ff and references therein. (g) Page
(10) El Nakat, J. H.; Dance, I. G.; Fisher, K. J.; Rice, D.; Willett, G. D. J.
Am. Chem. Soc. 1991, 113, 5141-5148. El Nakat, J. H.; Fisher, K.
J.; Dance, I. G.; Willett, G. D. Inorg. Chem. 1993, 32, 1931-1940.
Dance, I. G.; Fisher, K. J.; Willett, G. D. J. Chem. Soc., Dalton Trans.
1997, 2557-2561.
(11) Campbell, E. E. B.; Hasselberger, B.; Ulmer, G.; Busmann, H. G.;
Hertel, I. V. J. Chem. Phys. 1990, 93, 6900-7; Pozniak, B.; Dunbar,
R. C. Int. J. Mass Spectrom. 1994, 133, 97-110.
(12) (a) Delley, B. J. Chem. Phys. 1990, 92, 508-517. (b) Delley, B. In
Modern density functional theory: a tool for chemistry; Seminario, J.
M., Politzer, P., Eds.; Elsevier: Amsterdam, 1995; Vol. 2; pp 221-
254. (c) MSI, http://www.msi.com.
1
01 ff and references therein. (h) Page 162 ff and references therein.
(i) Page 228 ff and references therein.
(
8) Dunbar, K. R.; Heintz, R. A. Prog. Inorg. Chem. 1997, 45, 283-391.
Miller, J. S.; Manson, J. L. Acc. Chem. Res. 2001, 34, 563-570.
Cernak, J.; Orenda, M.; Potocnak, I.; Chomic, J.; Orendacova, A.;
Skorsepa, J.; Feher, A. Coord. Chem. ReV. 2002, 224, 51-66.
9) Bigelow, J. H. Inorg. Synth. 1946, 2, 225-227.
(
Inorganic Chemistry, Vol. 41, No. 13, 2002 3561

Dance et al.
Table 1. Metal-Containing Ions Observed after Laser Ablation of
M(CN)2 (M ) Co, Ni, Zn, Cd, Hg), “Fe[Fe(CN)6]‚xH2O”, Ag3[M(CN)6]
a,b
(M ) Fe,Co), and Ag2[Fe(CN)5(NO)]
metal(s)
positive ions
negative ions
+
+ c
+ c
-
(n ) 1-27)d,e
Zn
Cd
Zn , Zn
2
, [Zn(CN)]
[Zn
n
(CN)2n+1
n
]
+
+
, [Cd(CN)]+
(CN)2n+1]-
Cd , Cd
2
[Cd
f
(
n ) 1, 2, 8-27, 29, 30)
+
+
+
-
] , [Hg(CN)
3
]-
-
Hg
Hg , Hg
2
, [Hg(CN)] ,
Hg , [Hg(CN)
2
+
g
[
Hg
Hg
Hg
2
2
2
(CN)] ,
(CN)
(CN)
+
g
[
2
]
] ,
3
+
g
[
Feh
Co
Ni
Fe+
[Fe(CN)
[
[
[Co(CN)
[
[
] , [Fe(CN)
-
] ,
-
2
3
-
g
- g
4
Fe
Fe
2
(CN)
3
] , [Fe
2
(CN) ] ,
-
g
2
(CN)
5
]
Co+
] , [Co(CN)
-
] ,
-
2
3
-
-
Co
3
2
(CN)
3
] , [Co
2
(CN)
4
5
] ,
-
-
Co
(CN)
4
] , [Co
3
(CN)
]
+
+
-
-
Ni , [Ni
2
(CN)] ,
[Ni(CN)
[Ni
2
] , [Ni
2
(CN)
3
] ,
+
+ g
-
4
[
Ni
3
(CN)
2
] , [Ni
4
(CN)
(CN)] ,
3
]
3
(CN)
2
]
Fe, Agi K , Fe , Ag , [Ag
+ g
+ g
+
+ c
[Ag(CN)
[Ag
AgFe(CN)
] , [Ag
-
(CN)
] ,
-
3
2
2
Figure 1. Negative ion mass spectrum obtained by the laser ablation of
+
c
]+ c
-
-
[Ag
3
(CN)
2
] , [Ag
4
(CN)
3
3
(CN)
4
] , [Fe(CN)
3
] ,
4
-2
Zn(CN)2 at 1064 nm with power density ≈ 1.8 × 10 MW cm , showing
-
]-
[
4
] , [Ag
(CN)
2
Fe(CN)
5
-
the formation of [Znn(CN)2n+1] (n ) 1-27) and (at m/z < 200) various
Fe, Agj Na , Fe , Ag
+
+
+
[Ag(CN)
] , [Ag
-
] ,
-
2
2
3
-
-
- c
CxNy . Inset is a 3.33× vertical expansion.
[
[
[
[
[
[
Ag
2
3
(CN)
4
] , [Fe(CN)
3
] ,
-
c
- c
Fe
Fe
(CN)
(CN)
3
] , [Fe
2
(CN) ] ,
5
-
-
c
- c
Figure 1. Evidently, some fragmentation of CN is occurring.
3
7
] , [AgFe
2
(CN)
6
] ,
4
-
c
- c
Ag
Ag
2
Fe
2
(CN)
7
] , [AgFe(CN)
] ,
] ,
These results contrast with the ablation of MCN (M ) Cu,
-
c
- c
2
Fe(CN)
5
] , [Ag
3
Fe(CN)
6
-
c
2
AgFe
3
(CN)
8
]
Ag) where such decomposition is not significant. Several
Co, Agk K , Co , Ag , Ag
+ g
+ g
+
+,
Ag , [Co(CN)
-
] , [Co
-
(CN)
] ,
-
-
-
2
2
2
3
] ,
of the C
N
x y
obtained by ablation of M(CN)
2
, namely C
x
N ,
+
c
-
-
3
[
[
[
[
[
Ag
Ag
Ag
2
3
4
(CN)] ,
(CN)
(CN)
[Ag(CN)
2
] , [Ag
2
(CN)
+
c
c
-
-
-
-, x ) 6,
2
] ,
3
[Ag
[Ag
[Ag
3
(CN)
2
2
4
] , [AgCo(CN)
Co(CN)
Co(CN)
3
] ,
x ) 3, 7, 10; C
8, 10, 12, 14; and C
partway through our investigation, reports were made
obtained by laser ablation of K
thereafter, our detailed study of C
x
N
2
x 4
, x ) 4, 6, 8, 10, 14, 16; C N
+
- c
- c
] ,
4
] , [AgCo(CN)
4
] ,
-
+
c
- c
5 5
N , were studied in detail. However,
AgCo(CN)] ,
5
]
+
2 2
Ag Co(CN) ]
c
14,15
of
and
-
16,17
a
See text. Varying amounts of CN- and polyatomic CxNy- are produced
C
x
N
y
3
[Fe(CN)
6
],
also. b Species listed are those observed using both 1064 and 532 nm
irradiation, except as noted. Not observed with 532 nm irradiation. See
-
N
x y
was discontinued. The
c
d
results for the anions that we observed are summarized in
e
f
Figure 1. Species with n ) 2-27 not observed at 532 nm. Only the anions
g
the Supporting Information. It should be mentioned that a
with n ) 1, 2 observed with 532 nm irradiation. Observed with 532 nm
h
III
III
i
-
irradiation only. From Fe [Fe (CN)6]‚xH2O. From Ag3[Fe(CN)6]. HCN-
different distribution of C
x
N
y
anions is observed in the
].
j
containing cations are detected also (see text). From Ag2[Fe(CN)5(NO)].
current work than after laser ablation of the K3 or 4[M(CN)
6
k
From Ag3[Co(CN)6].
2
Laser ablation of Hg(CN) gives a particularly wide range
x y
of C N
structures, without specification of the electronic state, so that the
lowest energy electronic configuration is obtained. In addition,
smearing techniques allowing partial occupancy of orbitals in the
vicinity of the Fermi level were incorporated during optimization.12a,b
This permits the energy minimization to access alternative close-
lying electronic states and to find the local minimum in geometry-
electronic space (the charge smearing was reduced to zero for the
final optimization of each species). Second derivative (frequency)
calculations were not generally made to confirm that stationary
points were true minima, but experience with the quality of the
gradients during optimizations supports the assumption of true
minima in most cases. Some species evidently possessed complex
geometry-electronic surfaces, and these are identified in the
presentation of results.
-, which is consistent with the fact that thermal
2 2
decomposition of Hg(CN) yields cyanogen, (CN) , together
with paracyanogen (which itself is appreciable degraded at
1
8
1
200 °C).
Precursors Zn(CN)
2
2 2
and Cd(CN) . Ablation of M(CN)
(
M ) Zn, Cd) using 1064 nm radiation gives a positive ion
+
spectrum showing mainly M but with minor amounts of
M
+
+
2
and [M(CN)] . However, the negative ion spectra
produced from these substrates with the IR laser are more
remarkable. Figure 1 shows a spectrum for M ) Zn, with
-
the long series of ions [Zn (CN)2n+1] extending for 27
n
-
-
members from [Zn(CN)
3
] to [Zn27(CN)55] (n ) 1-27).
-
The spectra of C
x
N
y
(see previously) occur in the lower
Results and Interpretation
part of this mass range. High resolution spectra have been
measured and satisfactorily simulated for the complexes with
n ) 1-12. The identities of the higher members of the series
follow from the common mass separation, ∆(m/z) ) 118
units.
General. The signals observed in the mass spectra of laser-
ablated M(CN)
and, for M ) Ni, Zn, Cd, or Hg, the isotopomer patterns.
Co is monoisotopic, and species produced from Co(CN)
2
were assigned using a combination of mass
2
were confirmed by measurement of exact masses. A sum-
mary of all metal-containing species detected is given in
Table 1.
(
(
(
14) Wang, C. R.; Huang, R. B.; Liu, Z. Y.; Zheng, L. S. Chem. Phys.
Lett. 1995, 237, 463-467.
15) Tang, Z.-C.; Huang, R.-B.; Shi, L.; Zheng, L.-S. Int. J. Mass Spectrom.
1
998, 173, 71.
The ablation of most of the compounds studied here leads
17
16) In another study of the laser ablation products of K3[Fe(CN)6] by
TOF MS, in which we presume lower power densities were used,
-
to varying amounts of polyatomic anions of the type C
x
N
y
,
+
-
[K(KCN)x] and [(KCN)x(CN)] were the ions detected.
-
in addition to CN and M-containing species, for example,
(
17) Zhang, X.-G.; Li, H.-Y.; Ma, C.-S.; Wang, X.-Y.; Bai, J.-L.; He, G.-
Z.; Lou, N.-O. Chem. Phys. Lett. 1997, 274, 115.
(
13) Becke, A. D. Phys. ReV. A 1988, 38, 3098-3100. Lee, C.; Yang, W.;
(18) Brotherton, T. K.; Lynn, J. W. Chem. ReV. 1959, 59, 844 and references
Parr, R. G. Phys. ReV. B 1988, 37, 785-789.
therein.
3562 Inorganic Chemistry, Vol. 41, No. 13, 2002

Metal Cyanide Ions in the Gas Phase
It is notable that the relative intensities of the ions in the
-
series [Zn
n
(CN)2n+1] are highest in the central region of the
series, maximizing at n ) 15, 19, 23 with odd numbers of
metal atoms: this is unlike the commonly observed general
reduction in intensity with increasing mass and signifies
-
enhanced stability of ions [Zn
n
(CN)2n+1] with n ∼ 19. We
note also that these ions all contain zinc in its normal +II
oxidation state.
The only Zn-containing ions detected when Zn(CN)
ablated using 532 nm radiation were Zn and [Zn(CN)
2
was
+
-
3
] .
Negative ion spectra obtained from Cd(CN)
2
using 1064
-
nm radiation also show the spectra of C
N
x y
at lower masses.
-
n
Above m/z = 1000, an extended series of ions [Cd (CN)2n+1]
is observed in which n ) 8-27, and possibly 29, 30. The
identity of the species with n ) 8 was confirmed by a
simulation of the isotopic pattern measured in the narrow-
band spectrum. The identity of other members of the series
follows from the common m/z separation of 164 units and by
analogy with the better-characterized zinc analogues. When
Figure 2. Positive ion mass spectrum obtained by the laser ablation of
Hg(CN)2 at 532 nm with power density ≈ 2.7 MW cm-2, showing the
formation of dimetallic cations.
obtained using 532 nm radiation with irradiances 17-66 MW
-
2
-
-
cm . The complexes [Fe(CN) ] and [Fe(CN)3] were
2
5
32 nm radiation is used, the only cyano anions observed
definitely established, with measurement of the signals from
-
-
+
54
-
are [Cd(CN)
3 2 5
] and [Cd (CN) ] , and Cd is the sole cation.
2 3
the Fe-containing isotopomers. The species [Fe (CN) ] ,
-
-
There are several distinctive features of the spectra of the
2 4 2 5
[Fe (CN) ] , and [Fe (CN) ] were observed only as the most
-
-
-
series [Cd
n
(CN)2n+1] . First, no evidence was found for
2 3
intense isotopomer. The ions [Fe(CN) ] , [Fe(CN) ] , and
-
members with n < 8 when 1064 nm radiation was used.
This contrasts with the series [Zn
[Fe(CN) ] were detected in an earlier time-of-flight mass
4
-
n
(CN)2n+1
]
described
spectrometric (TOF MS) study of the products of laser
1
5
previously. However, two of the missing members of the
Cd series, those with n ) 1, 2, are the only cyano complexes
observed in the negative ion mass spectrum when ablation
is carried out with 532 nm radiation. Second, there are
regions of the spectrum where alternation of signal intensity
occurs. In the region n ) 14-20, the most prominent species
with n ) 15, 17, 19 again have an odd number of metal
atoms, as is also found for their Zn congeners. In contrast,
in the region n ) 8-14, the most abundant species (n ) 8,
3 6 4 6
ablation of K [Fe(CN) ] and K [Fe(CN) ].
Precursor Ag [Fe(CN) ]. When ablation was carried out
3
6
using 1064 nm irradiation, the cyano complexes that could
be detected in the positive ion mass spectrum of this salt
+
2
were the known cations [Ag (CN)n-1] (n ) 1-4) and
n
+
several cations of formula [Ag (CN) (NCH) ] , for ex-
n
n-1
m
+
+
ample, [Ag (CN)(NCH)] , [Ag (CN) (NCH) ] (m ) 1,
2
3
2
m
2): the resolution was more than sufficient to detect a
difference of 1 mass unit. These HCN complexes indicate
the presence of a proton source even after the salt had been
vacuum-dried. The corresponding negative ion spectrum
10, 12, 14) have even numbers of metal atoms. Finally, we
note that, as for the cyanozincates, the Cd complexes contain
the metal in the formal +II oxidation state.
-
2
showed the homometallic species [Ag (CN) ] (n ) 1-3)
n
n+1
-
III
III
2
Precursor Hg(CN) . The positive ion mass spectrum
and [Fe(CN) ] (also produced in ablation of Fe [Fe (CN) ]‚
3
6
-
obtained when Hg(CN)
contains Hg as a major ion and [Hg(CN)] and Hg
minor ions. When 532 nm radiation is used, the dimercury
species [Hg
2
is ablated at 1064 or 532 nm
2 2
xH O), but no [Fe(CN) ] (which was observed on ablation
of Fe [Fe (CN) ]‚xH O). In addition, the two new hetero-
metallic complexes [AgFe(CN) ] and [Ag Fe(CN) ] were
detected. CID of [AgFe(CN) ] (collision energy 170 eV)
gave [Fe(CN) ] as the major product: minor species were
[Ag(CN)2] and [Fe(CN) ] , while CN became a major
+
+
+
III
III
2
as
6
2
-
-
4
2
5
+
-
2
(CN)
x
] (x ) 1-3) are observed also (Figure
4
+
-
2). The cation [Hg
2
(CN)] invariably has low abundance and
3
-
-
-
indeed does not occur in Figure 2, but the corresponding di-
and tricyanides are the major species observed in some of
the spectra. (The dependence of spectra on the extent of
2
species at long collision times, consistent with the fact that
-
-
CID of [Fe(CN) ] itself (collision energy 350 eV) gave CN
3
-
ablation has been mentioned.)
(major) and [Fe(CN) ] (minor).
2
-
]- are major
The complexes [Hg(CN)
2
]
and [Hg(CN)
3
With ablation at 532 nm, the positive ion spectrum of Ag
[Fe(CN)
3
-
anionic products of ablation using either 1064 or 532 nm
radiation. There was no evidence for [Hg(CN)] . An ad-
ditional species observed with both 1064 and 532 nm
radiation was Hg .
6
] showed no evidence for cyano complexes. Only
-
+
+
signals from K (contaminant), Fe , and (at higher power
+
levels) Ag were observed, together with two as-yet-
-
unidentified signals at m/z ) 277, 339. The negative ions
that were detected under these conditions were the same
species found using 1064 nm irradiation.
III
III
+
Precursor Fe [Fe (CN)
6
2
]‚xH O. Only Fe was observed
in the positive ion spectrum of this substance whether dried
under vacuum alone or under vacuum and then at 200 °C.
When relatively low laser power densities were used,
evidence could be obtained for a limited series of Fe-
containing anions. In our experiments, the best results were
2 5
Precursor Ag [Fe(CN) (NO)]. No nitrosyl complexes
were detected when this salt was irradiated at either 532 or
1064 nm. Signals from a particularly wide range of homo-
and heterometallic cyanometalates were observed when
Inorganic Chemistry, Vol. 41, No. 13, 2002 3563

Dance et al.
(
CN)
2
except for [Co
3
(CN)
4
2
]- and [Co
3
(CN)
5
]-. Also ob-
-
served were Ag (not seen in the ablation of AgCN) and
the heterometallic anions [Ag
-
n
Co(CN)n+2] (n ) 1, 2) and
-
[
[
[
[
Ag
AgCo(CN)
Co(CN)
Ag(CN)
n
Co(CN)n+3
]
(n ) 1, 2). A CID experiment with
-
-
3
] (collision energy 130 eV) shows that CN ,
] , and [Co(CN)
] is a minor product.
-
-
2
3
]
are major products and
-
2
3 6
The anions observed when Ag [Co(CN) ] was ablated
using 532 nm irradiation were generally similar to those
observed with ablation at 1064 nm, but the only heterome-
-
tallic complex observed was [AgCo(CN)
3
] . The corre-
sponding positive ion spectra, while “clean”, provided
+
+
+
evidence for only K , Co , and Ag .
Precursor Ni(CN) . The positive ion mass spectrum
2
obtained by ablation of anhydrous Ni(CN)
2
at 1064 nm
Figure 3. Negative ion mass spectrum obtained by laser ablation of Ag2-
+
2
-2
contains signals from [Ni
n
(CN)n-1] (n ) 1-3), with the
[
Fe(CN)5(NO)] at 1064 nm with power density ≈ 1.8 × 10 MW cm
.
-
Ions are formulated AgxFey(CN)z and identified by their indices x, y, z.
relative abundances of the cations decreasing with increasing
n. When 532 nm radiation is used, the cation [Ni
+
4
(CN)
3
] is
ablation was carried out at 1064 nm (Figure 3, Table 1).
observed also but with a relative abundance of less than 1%.
Anions are produced according to the general formula
-
-
These include [AgFe(CN)
also from Ag [Fe(CN) ]) and possibly the next member of
this series, [Ag
can be regarded as [Fe
4 2 5
] and [Ag Fe(CN) ] (formed
-
3
6
[Ni (CN) ] (n ) 1-3).
n
n+1
-
-
I
3
Fe(CN)
6
II
] . The complexes [Ag
n
Fe
2
(CN)n+5
]
The occurrence of M only in these nickel complexes
I
-
I
II
2
(CN)
5
(Ag CN)
n
] , and this formula-
contrasts with the occurrence of a mixture of M and M in
the gas-phase anions derived from the various cyano-species
of Fe and Co, and the formation only of gaseous cyano-
-
tion adds weight to the assignment for [Fe
Similarly, the presence of [AgFe
AgCN)] } supports the occurrence of [Fe
2
(CN)
5
] itself.
{)[Fe (CN) -
3 7
-
3
(CN)
8
]
-
-
(
3
(CN)
7
] . The
metalates(II) from M(CN) (M ) Zn, Cd)).
2
corresponding positive ion spectrum is not nearly so infor-
mative. Overall, there was evidence for decomposition and/
or protonation, and the only metallic species observed with
Structural Chemistry of the Gas-Phase Ions. Zinc and
Cadmium Complexes. In view of the common formula,
-
[M (CN) ] , and the long series of anions that are
n
2n+1
+
+
+
+
certainty were Na , K , Fe , and Ag . Similarly, spectra
observed for M ) Zn and Cd, it seems unlikely that any
major change in the coordination number or geometry of
the metal centers occurs along the series. For each series,
observed using 532 nm ablation were quite uninformative.
-
n
The negative ion spectra showed evidence for [Ag (CN)n+1]
-
(n ) 1, 2) and decomposition/protonation products, and only
the first member, [M(CN) ] , is expected to have trigonal
3
monatomic species and decomposition/protonation products
planar coordination, and the stability of this geometry over
alternatives has been demonstrated by density functional
calculations for [Zn(CN) ] . Accordingly, we have proposed
3
could be detected in the positive ion spectra.
+
-
3
Precursor Co(CN)
2
. The signal of Co only is observed
in the positive ion mass spectrum of laser-ablated Co(CN)
2
.
that such coordination be maintained in the larger members
of the series by use of the linear cyanide bridges that are
common to other extended cyanide structures involving Zn
2
The negative ion spectrum provides good evidence for the
-
I
-
complexes [Co
n
3
(CN)n+1] (n ) 1, 2, formally Co ), [Co(CN) ]
II
-
I
II
(Co ), and [Co
2
(CN)
4
] (Co /Co ). Additional weak signals
or Cd. Thus, we formulate the anions as [(NC) M{(µ-CN)M-
-
at m/z ) 280.8 and 306.8 observed when 532 nm radiation
(CN)}n-1(CN)] . A number of structural possibilities exist,
-2
is used with a relatively low power density (ca. 6 MW cm )
such as the cis and trans extended sequences 1 and 2. On
-
-
are those of [Co
3
(CN)
4
] and [Co
3
(CN)
5
] , respectively. A
-
CID experiment on [Co
2
(CN)
3
] (collision energy 180 eV)
-
-
gave mainly CN but also significant amounts of [Co(CN)
2
] .
-
-
The species [Co(CN)
2
]
and [Co(CN)
3
]
(along with
-
[
Co(CN)] , which we do not observe) have been detected
usingTOFMSintheproductsoflaserablationofK
1
9
3 6
[Co(CN) ].
Precursor Ag [Co(CN) ]. Using 1064 nm radiation for
3
6
2
ablation, positive ions observed were the previously reported
+
[
Ag
n
(CN)n-1] (n ) 1-4) and the new mixed-metal cations
+
+
[
AgCo(CN)] and [Ag
The negative ion mass spectrum of Ag
at 1064 nm shows evidence for the known [Ag
2 2
Co(CN) ] .
3
[Co(CN)
6
] ablated
2
-
n
(CN)n-1]
(n ) 1-3) and all the anions observed on ablation of Co-
(
19) Huang, R. B.; Wang, C.-R.; Liu, Z. Y.; Zheng, L. S.; Qi, F.; Sheng,
L. S.; Yu, S. Q.; Zhang, Y. W. Z. Phys. D: At. Mol. Clusters 1995,
33, 49-52.
3564 Inorganic Chemistry, Vol. 41, No. 13, 2002

Metal Cyanide Ions in the Gas Phase
Hg-Hg isomers 22B and 22C, or isomers 22D (at +35 kcal
-
1
-1
mol ) and 22E (at +58 kcal mol ).
+
The complex [Hg
2
(CN)
3
] , of Hg(II), is thought to have
+
the linear structure [(NC)Hg(CN)Hg(CN)] in the condensed
phase (see later), and DF calculations show this to be an
electronically favorable structure for the gas phase.
Cyanometalates of Iron, Cobalt, and Nickel. The
geometric and electronic structures of representative anionic
-
-
cyanide complexes [M(CN)
2
-
3
] (M ) Fe, Co, Ni), [M(CN) ]
-
-
(
(
(
M ) Fe, Co), [M
M ) Fe, Co), [M
M ) Co, Ni), [Co
2
(CN)
3
] (M ) Fe, Co, Ni), [M
2
(CN)
(CN)
4
]
]
-
2
(CN)
5
-
]
(M ) Fe, Zn), [M
3
4
-
3
(CN)
5
] , and [M
3
(CN)
7
] (M ) Fe, Zn)
have been explored using density functional calculations. For
some species, which are noted, there are close-lying elec-
tronic states, and for these, full characterization of the energy
surfaces for both geometric and electronic structure has not
been undertaken.
Figure 4. Axial and side views of the helical structure type calculated for
]- (M ) Fe, Co, Ni) showed
The calculations for [M(CN)
2
-
ions [Mn(CN)2n+1] , M ) Zn, Cd: M, black; C, light gray; N, dark gray.
linear or near-linear structures with C-bound terminal
cyanides to be the more stable than N-bound by ca. 10 kcal
The key feature is the location of CN from adjacent turns in the secondary
axial positions of the primarily trigonal coordinate metal atoms. Analogous
3
helices with more metals per turn are possible.
-1
mol . On the basis of these calculations, it is assumed that
any terminal cyanides in other complexes are also C-bound.
The geometry-energy surface for these ions was found to
be quite flat, with small deviations from linearity having
the basis of (1) the enhanced abundances of middle members
of the series, (2) density functional calculations of charge
distributions, and (3) force field calculations, we proposed
insignificant effect on the binding energies.
that helical structures such as that shown in Figure 4 are the
-
Calculations for [M(CN)
3
]
involved three structures:
-
most likely for ions in the series [M
n
(CN)2n+1] , M ) Zn,
1
3A, trigonal planar (D3h); 13B, trigonal pyramidal
3
Cd. Details of the helical structure shown in Figure 4,
including the angled conformations of the terminal CN
ligands, and the juxtapositions of successive strands of the
-
(C
3V); and 13C, nontrigonal planar (C2V). For [Fe(CN)
3
] ,
-
-
[Co(CN)
3
] , and [Ni(CN)
3
] , structure 13C is most stable.
-
The nonobservation of [Ni(CN)
3
] is not thought to be a
3
chain, are presented and justified in our previous report.
consequence of an uncompetitive electronic affinity of [Ni-
The cations M+ and M
+
(M ) Zn, Cd) are well-
0
0
0
0
2
3 3 3 3
(CN) ] , because [Ni(CN) ] , [Co(CN) ] , and [Fe(CN) ] are
established gas-phase species.
calculated to have similar electron affinities, and electron
0
Throughout the following, the structures for M
denoted xyA, xyB, xyC, and so forth, usually in order of
x
(CN)
y
are
attachment to [Ni(CN)
3
] is calculated to be more exergonic
0
-
than to [Ni(CN)
2
] , which does appear as [Ni(CN)
2
] .
decreasing stability.
+
Mercury Complexes. The cations Hg
x
(x ) 1, 2) and
-
the anion Hg are particularly well-known gas-phase species,
but we could find no previous reports of gas phase [Hg
x
-
+
y 2
(CN) ] ions. The complex [Hg (CN)] is formally a mercury-
(
I) complex and, thus, could contain a Hg-to-Hg bond. Our
-
density functional (DF) calculations indicate that the [Hg-
Hg-C-N] structure is 20 kcal mol more stable than
For ions of composition [M (CN) ] , the structures
2
3
+
-1
23A-E were investigated. For Fe and Co, structure 23A is
slightly (<10 kcal mol ) more stable than 23B, but for Ni,
linear 23B is slightly more stable than 23A. The electronic
structures of these stable species are complex, with HOMO-
LUMO gaps less than 0.1 eV, and full description of the
geometry-electronic-energy surface will require further cal-
+
+
-1
[Hg-C-N-Hg] . The species [Hg
2
(CN)
2
] is formally a
I
II
mixed oxidation state species, Hg /Hg . Here, too, Hg-Hg
bonding is a possibility, but DF calculations show that
optimized structure 22A without Hg-Hg is 25 kcal mol
more stable for [Hg
-
1
+
2
(CN)
2
] than either of the two optimized
Inorganic Chemistry, Vol. 41, No. 13, 2002 3565

Dance et al.
-
1
culations. However, it is evident that the more bridged
structures 23C, 23D, and 23E are much less stable. Linear
which are very similar (∼2 kcal mol ) in energy and, as
expected, have large HOMO-LUMO gaps. The optimized
geometry of 25A is strongly pyramidal at both Fe atoms,
with C-Fe-C(N) angles 100-106°.
-
2
2
3B is the most stable structure for [Cu
2
CN)
3
] , as for
-
-
[Ni
2
CN)
3
] . In the case of [Co
2
(CN)
3
] , the collisionally
induced dissociation to mainly CN and significant amounts
-
-
of [Co(CN)
2
] does not differentiate structures 23A and 23B.
3 4
Ions [M (CN)
]- were observed for M ) Co, Ni, Ag. The
connectivities investigated were extended 34A, already
2
established for Ag, and double-bridged 34B based on the
favorable CN bridging found in 24F and 25B. For Ni,
structure 34B optimized to 34C. Structure 34A was the more
-
1
stable for both Co (by 17 kcal mol ) and Ni (by 37 kcal
-1
mol ), and no stabilization was found for nonlinear variants
of 34A. The electronic structures of the extended linear chain
of 34A for both Co and Ni are complex, with notably high
spin ground states of S ) 3 for Co.
]- observed
2 4
For the odd-electron composition [M (CN)
for Fe and Co, the four connectivities postulated were 24A,
4B, 24C, and 24D: other cyanide bridging modes already
2
demonstrated to be less favorable were not investigated.
Some of these (24A, 24B) underwent structural change
during optimization without symmetry constraints. Thus,
M-M bonded 24A for Co changed stereochemistry at both
M atoms, one becoming T shaped with close to linear NC-
M-CN coordination, and the other M became trigonal
orthogonal, as 24E. Structure 24B opened to 24F for both
Fe and Co, introducing additional possibilities for isomerism
of C/N and isomeric stereochemistry at the M atoms, and
led to 24F as an energy minimum. For both Fe and Co,
isomer 24F is more stable than the others by ca. 20 kcal
3 5
The composition [M (CN)
]- was observed only for Co.
Only one connectivity was explored, on the basis of the
considerable stability of the 34A structure, by addition of
CN at the central Co. The preferred geometry is T-shaped
-1
mol . Among the other structures for iron, the isomers 24A,
at Co, as in 35A, and again, there is a high-spin ground state,
24C, and 24E with Fe-Fe bonding are less stable than 24D,
24F, and 24G without it. For Co, the isomers 24G, 24D,
24E, and 24C all have similar energy. For the most probable
5
S ) /
2
. The energy surface for bending at bridging CN and
at Co is very flat: for example, 70° bending at the outer Co
-
1
(
structure 35B) increases the energy by only 4 kcal mol .
structure, 24F, the singly occupied HOMO (SHOMO) occurs
at relatively high energy (-1.0 eV Fe, -1.3 eV Co),
reflecting the reduced character of these species, and the
SHOMO is separated from the LUMO by 0.13 eV (Fe), 0.93
eV (Co).
3 7
The composition [M (CN)
]- is again M(II) oxidation state
and was observed only for Fe and Zn. Following the
principles evident from the smaller structures, connectivities
with extended single bridging (37A) and with double
bridging (37B) were investigated. For Fe, doubly bridged
-
1
structure 37B was the more stable, by ca. 11 kcal mol . In
contrast, for Zn, the extended structure is more stable by
2 5
The ion [M (CN)
]- was not observed for Co and Ni, even
though it represents the normal M(II) oxidation state. The
-
three connectivities explored for Fe
2
(CN)
5
are 25A, 25B,
and 25C. Isomer 25C is far less stable than the other two,
3566 Inorganic Chemistry, Vol. 41, No. 13, 2002

Metal Cyanide Ions in the Gas Phase
2 3
Co(CN) ] . However, the CID of [AgCo(CN)
]- includes
-
[
-
-
-
the fragments [Co(CN)
and [Ag(CN)
3
] , [Co(CN)
] (minor). Here, the formation of [Ag(CN)
2
] , and CN (all major)
-
-
2
2
]
is consistent with a straight-chain structure NC-Ag-(CN)-
Co-CN, but this structure does not account for the formation
-
-
3 3
of [Co(CN) ] . Therefore, it seems that [AgCo(CN) ] can
exist with structures other than the expected extended chain,
and DF calculations were applied to this question. The three
-
structures considered for [AgCo(CN)
3
] are AgCoA, AgCoB,
AgCoC. AgCoB is the only single structure consistent with
the CID data, but the DF calculations indicate that it is 28
-
1
kcal mol less stable than the extended chain, and uncer-
-
tainty remains about the structure(s) of [AgCo(CN)
3
] .
Discussion
We have shown that anionic binary and ternary metal
cyanide complexes can be generated in the gas phase for
metals in groups 8-12 of the periodic table. Extended series
-
[M
n
(CN)2n+1] occur for Zn and Cd, containing up to 27
(Zn) or 30 (Cd) metal atoms, and these have been interpreted
in terms of the formation of helices in the gas phase. For
Cu and Ag, extended linear rods are probable. In both series,
the formal oxidation states of the complexes are normal. For
Hg, the compositions and calculations provide no indication
that Hg-Hg bonded complexes are stabilized in the gas
Figure 5. Structures for the heterometallic complexes, M ) Co or Ni.
+
phase, except in the mercurous complex [Hg-Hg-CN] .
-
-
1
For the transition metals, the sizes of [M (CN) ] complexes
>
25 kcal mol , and there appears to be a barrier-free
x
y
in the gas phase are restricted in our experiments, the largest
pathway from 37B to 37A.
-
-
3 7 4 9
being [Fe (CN) ] , although there is a trace of [Fe (CN) ] .
Heterometallic Complexes. All of the anions listed in
Table 1 as containing Fe and Ag, or Co and Ag, can be
formulated as AgCN additions to the homometallic anions
already discussed. Specifically, and noting the formal oxi-
Experiments allowing the formation of mixed Fe + Ag
species, and of Co + Ag species, generate complexes that
can be interpreted as having AgCN moieties added to
terminal CN of the homometallic complexes, generating
M-CN-Ag-CN sections.
-
II
-
I
dation states, [Ag
n
Fe(CN)n+3
]
3
is [Fe (CN) ] ‚nAg CN,
-
II
-
I
-
[
Ag
n
Fe
2
(CN)n+5] is [Fe
2
(CN)
5 3 8
] ‚nAg CN, [AgFe (CN) ]
II
-
I
-
I
-
is [Fe (CN)
nAg CN, and [Ag
3
7
] ‚Ag CN, [Ag Co(CN)n+2] is [Co (CN)
Co(CN)n+3] is [Co (CN)
analogy with the proposed linear structures of [Ag
n
2
] ‚
Density functional calculations provide general insight into
the probable structures of the transition complexes in the
gas phase. The compositions of the complexes result in
undercoordination of the metals relative to the norm for
condensed phases. Cyanide bridging is prevalent, in prefer-
ence to metal-metal bonding (the exception is Fe-23A). The
two favored bridge geometries are linear M-CN-M (B1)
for single bridges and B2 for double bridges. We note that
I
-
II
-
I
n
3
] ‚nAg CN. By
2
+
n
(CN)n-1
]
-
and [Ag
n
(CN)n+1] , such formulations suggest structures with
AgCN attached at terminal CN ligands, to generate linear
terminal moieties NCAgNCM- or NCAgCNM-. Using the
structural findings for the homometallic anionic species,
structures for the heterometallic anions are then readily
-
1
proposed, as in Figure 5 (M ) Fe or Co) for [AgM(CN)
4
] ,
η -CN bridging (B3) is not supported by the calculations.
-
-
-
[
Ag
2
M(CN)
5
] , [Ag
3
Fe(CN)
6
] , [AgFe
2
(CN)
6
] , [Ag
2
Fe
2
-
In general, the double cyanide bridging increases the
otherwise low coordination numbers of the metal atoms, but
this does not provide marked energy stabilization, and this
is probably because the geometry of the double bridge B2
diminishes the quality of overlap and interaction between
the CN orbitals (particularly at N) and metal orbitals. Most
generally, it appears that the structures proposed involve a
]-, and [AgM
-
(CN)
7
3
(CN)
8
] .
The collisionally induced dissociation (CID) of [AgFe-
-
-
-
(
[
CN)
4
]
yielded [Fe(CN)
3
]
(major) and [Fe(CN)
2
]
and
-
-
Ag(CN)
2
] (minors), plus CN , entirely consistent with the
-
structure proposed. The heterometal species [AgCo(CN)
and [Ag
3
]
-
2
Co(CN)
4
]
are formally AgCN adducts of
Inorganic Chemistry, Vol. 41, No. 13, 2002 3567

Dance et al.
hosts in a variety of clathrate compounds.22 Solid Zn(CN)
and Cd(CN) have the anti-Cu O structure, with tetrahedrally
compromise between increased metal coordination with
poorer (double, B2) cyanide bridging and reduced metal
2
2
2
coordination with better (single, B1) cyanide bridging. For
coordinated metal ions connected via bridging cyanides
M-CN-M.
-
23a
2 4
[M (CN) ] , the double bridging allowing three-coordination
of both metals is more stable, and double bridging occurs in
Several of the Hg/CN stoichiometries that we observe for
gas-phase species have been established in condensed phases.
-
the better of the two structures for [Fe
bridging is calculated to be more favorable for [M
3
(CN)
7
] , while single
-
+
3
(CN)
4
]
Thus, the cation [Hg
produced from Hg(CN)
2
(CN)
3
] , considered to be linear, is
2
4
-
(
Co, Ni), and there is no significant difference between the
2
in HF(l), while Hg/CN ) 1/1 is
known only as nonmolecular [Hg(CN) ]
3
) and is likely to occur in the salts Hg(CN)-
BF ) and Hg(CN)(AsF ). Similar strong (near-)linear
-
+
two structure types for [M
2
(CN)
5
] (Co, Ni).
∞
that occurs in
2
5
Hg(CN)(NO
2
4
(
4
6
3b
bonding is found in the structure of Hg(CN)
2
(s) itself.2 The
-
anion [Hg(CN)
solvents.
3
]
has been shown to occur in various
This ion is found in planar form, with weak
interionic Hg‚‚N bonding, in the structure of CsHg(CN)
On the other hand, the cation [Hg
] (g) have no counterparts in condensed phases,
because CN causes disproportionation of Hg(I). Similarly,
7
g,26
27
3
.
+
2
(CN)] (g) and the anion
-
[
Hg(CN)
2
Another general result is that three-coordinate transition
metals adopt stereochemistries other than trigonal planar,
namely trigonal pyramidal and T-shaped: C/N isomerism
in B1 is not a significant energy discriminator.
-
+
the species [Hg
2
(CN)
2
] (g) is unknown in condensed phases.
However, instances of formally Hg(I)/Hg(II) complexes of
4
+
Hg are known, for example, the cation [Hg
3
2
(dppm)
3
]
(dppm
The electronic structure and electronic population of the
gaseous transition metal cyanide complexes are significant
in several ways. Formal oxidation states in the gaseous
complexes are sometimes subnormal (relative to the con-
densed phase), as analyzed in more detail later. In a number
of cases, particularly linear complexes with B1 bridges, it
appears that the electronic structure involves close-lying or
degenerate orbitals at the Fermi level, and there are poten-
tially complex electronic states which have not been probed
in detail here. Further, we note that a number of the species
are predicted to be high spin, particularly the extended linear
chain structures of Co and Ni.
8
)
1,2-bis(diphenylphosphino)methane),
Hg-to-Hg bonding.
The production of gaseous complexes containing, formally,
and involve
III
III
Fe(I) and/or Fe(II) from Fe(III) precursors (Fe [Fe (CN)
xH O and Ag [Fe(CN) ]) is noteworthy. Homoleptic Fe(I)/
CN complexes are not well established, in contrast to their
6
]‚
2
3
6
-
7
h,29
Fe(II) and Fe(III) analogues.
We note the occurrence of
active sites of
reduced Fe-CN moieties at the FeNi and Fe
2
3
0
hydrogenase enzymes.
None of the Co(I) or Co(II) complexes described in the
present work or in ref 19 have analogues in condensed
phases. However, there is evidence for the occurrence of
In the following section, we compare the structural and
redox chemistry of gaseous and condensed phase systems,
before considering possibilities for the crystallization of new
compounds and structures inspired by the gas-phase results.
-
4-
Co(I)/CN complex [Co(CN)
5
]
as an intermediate in a
7i,31
I
variety of experiments,
has been synthesized but not yet fully characterized. For
3 4
and a salt formulated K Co (CN)
32
(
22) Kitazawa, K.; Nishikiori, S.; Kuroda, R.; Iwamoto, T. Chem. Lett.
1988, 459-462. Iwamoto, T. In Inclusion Compounds; Atwood, J.
L., Davies, J. E. D., MacNicol, D. D., Eds.; Oxford University Press:
Oxford, 1991; Vol. 5; pp 202. Kitazawa, K.; Nishikiori, S.; Iwamoto,
T. J. Chem. Soc., Dalton Trans. 1994, 3695-3710.
Comparison with Condensed Phases
In condensed phases, as in the gas phase, the chemistry
-
of zinc and cadmium with CN as a ligand involves the metal
(23) Wells, A. F. Structural Inorganic Chemistry, 5th ed; Clarendon:
Oxford, 1984. (a) Page 941 and references therein. (b) Page 943 and
references therein.
in the +II oxidation state exclusively. Although the species
+
[
M(CN)] (g) (M ) Zn, Cd) are new, stability constant data
(
24) Gillespie, R. J.; Hulme, R.; Humphreys, D. A. J. Chem. Soc.A 1971,
+
7f
(x-2)-
3574-3578.
x
are available for [M(CN)] (aq). The anions [M(CN) ]
M ) Zn or Cd; x ) 3, 4) are known in solution. However,
for M ) Zn, only salts of [Zn(CN)
ized structurally in the solid state. For M ) Cd, solid-state
(
(
25) Mahon, C.; Britton, D. Inorg. Chem. 1971, 10, 2331-2333.
26) Brodersen, K.; Hummel, H. U. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;
Pergamon: Oxford, 1987; Vol. 5; pp 1062 ff.
7f
(
2-
4
f
]
have been character-
7
(27) Thiele, G.; Bauer, R.; Messer, D. Naturwissenschaften 1974, 61, 215-
7f,20
structural data have been reported
for the discrete anions
and cyanide-bridged [(NC) Cd-CN-Cd-
Sb)[Cd(CN) ] contains an
216.
2
-
(28) Hammerle, B.; Muller, E. P.; Wilkinson, D. L.; Muller, G.; Peringer,
P. J. Chem. Soc., Chem. Commun. 1989, 1527-1528. Knoepfler-
Muhlecker, A.; Scheffter, B.; Kopacka, H.; Wurst, K.; Peringer, P. J.
Chem. Soc., Dalton Trans. 1999, 2525. Knoepfler-Muhlecker, A.;
Ellmerer-Muller, E.; Konrat, R.; Ongania, K.-H.; Wurst, K.; Peringer,
P. J. Chem. Soc., Dalton Trans. 1997, 1607.
(29) Hawker, P. N.; Twigg, M. V. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;
Pergamon: Oxford, 1987; Vol. 4, pp 1201 ff and references therein.
(30) Peters, J. W. Curr. Opin. Struct Biol. 1999, 9, 670-676. Siegbahn, P.
E. M.; Blomberg, M. R. A.; Wirstam, M.; Crabtree, R. H. J. Biol.
Inorg. Chem. 2001, 6, 460-466. Fan, H.-J.; Hall, M. B. J. Biol. Inorg.
Chem. 2001, 6, 467-473.
[
(
Cd(CN)
4
]
3
-
CN)
3
] . A salt of formula (Ph
infinite anionic chain with tetrahedral coordination of the
metal ion. In addition, polymeric anions of formulas
4
3
2
1
-
-
[
Cd
3
(CN)
7
] and [Cd
4
(CN)
9
] are known as metal complex
(
20) Kitazawa, T.; Takeda, M. J. Chem. Soc., Chem. Commun. 1993, 309-
10.
21) Kitazawa, T.; Akiyama, M.; Takashi, M.; Takeda, M. J. Chem. Soc.,
Chem. Commun. 1993, 1112-1113.
3
(
3568 Inorganic Chemistry, Vol. 41, No. 13, 2002

Metal Cyanide Ions in the Gas Phase
- 33,34
35
36
Co(II), [Co(CN)
4
]2
and both monomeric and dimeric
oxidation state than in the precursor. With or without a
change in oxidation state, most of the discrete gas-phase
complexes that are observed are unknown in condensed
phases. When gaseous and condensed phase cyano com-
-
complexes with Co(II)/CN ) 1/5 have been characterized
(
-2)-
structurally, and [Co(CN)
x
] x
aprotic solvents. Again, it is significant that ablation of a
cyano complex of Co(III), Ag [Co(CN) ], yields only
(x ) 1-5) occur in polar
3
4
-
3
6
plexes of Co(I) and Ni(I) are compared, the CN /M ratio is
complexes with lower oxidation states of Co, Co(I) and
Co(II).
smaller in the gas phase.
The findings reported here provide inspiration for the
further development of cyano-metalate complexes in the
condensed phases, by careful control of the associated cations
and the crystallization conditions. The helical structures and
the rod structures are not yet established in crystals, and
neither is the bridge B2. There are indications that rod or
extended structures such as 34A, 35A with the transition
metals will possess significant electronic structures with the
possibilities of electron conduction and/or high spin molec-
ular magnetism. An unusually high molecular spin state is
already established in cyanide bridged [Mn{Mn(MeOH) } -
The new complexes [Ni
CN)n+1] are produced from a Ni(II) precursor, Ni(CN)
n
(CN)n-1]+ (n > 1) and [Ni
n
-
-
(
2
,
with no evidence for coproduction of Ni(II) species. A few
-
examples of Ni(I)/CN complexes are extant. Salts in which
-
Ni(I)/CN ) 1/3 contain Ni-Ni bonded [(NC)
3
Ni-
] is
4
- 37
I
Ni(CN)
still incompletely characterized.
In summary, with the exception of M(CN)
3 3 4
] . A compound formulated as K [Ni (CN)
7i,38
2
(M ) Zn or
Cd), ablation of the cyano species that we have used as
precursors yields some or all species with a lower metal
3
8
4
(µ-CN)30{Mo(CN)
3 6
} ].
(
31) Buckingham, A. D.; Clark, C. R. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;
Pergamon: Oxford, 1987; Vol. 4, pp 6446 ff and references therein.
32) Watt, G. D.; Thompson, R. J. J. Inorg. Nucl. Chem. 1959, 9, 311-
Acknowledgment. This research was supported by the
(
(
(
Australian Research Council and the Natural Sciences and
Engineering Research Council of Canada. P.A.W.D., Honor-
ary Visiting Professor at UNSW, is grateful to the University
of Western Ontario for sabbatical leaves and a leave of
absence, during which this work was completed. H.H.H.
acknowledges an Australian Postgraduate Award.
3
14.
33) Carter, S. J.; Foxman, B. M.; Stuhl, L. S. J. Am. Chem. Soc. 1984,
06, 4265-4266.
34) Carter, S. J.; Foxman, B. M.; Stuhl, L. S. Inorg. Chem. 1986, 25,
1
2
888-2894.
(
(
35) Brown, L. D.; Raymond, K. N. Inorg. Chem. 1975, 14, 2590-2594.
36) Simon, G. L.; Adamson, A. W.; Dahl, L. F. J. Am. Chem. Soc. 1972,
9
4, 7654-7663. Brown, L. D.; Raymond, K. N.; Goldberg, S. Z. J.
Am. Chem. Soc. 1972, 94, 7664-7674.
Supporting Information Available: Table of anionic carbon-
nitride anions observed, with details of their collision-induced
dissociation (CID) products. This material is available free of charge
via the Internet at http://pubs.acs.org.
(
37) Jarchow, O.; Schuttz, H.; Nast, R. Angew. Chem., Int. Ed. Engl. 1970,
9
, 71. Jarchow, O. Z. Anorg. Allg. Chem. 1971, 383, 40-48.
(38) Nast, R.; Trakkay, T. Z. Naturforsch., B: Chem. Sci. 1954, 9, 78-
7
9. Sacconi, L.; Mani, F.; Bencini, A. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;
Pergamon: Oxford, 1987; Vol. 5; p 37.
IC011227D
Inorganic Chemistry, Vol. 41, No. 13, 2002 3569