Synthesis of 1,2-bis(di-tert-butylphosphino)ethane (dtbpe) complexes of nickel: Radical coupling and reduction reactions promoted by the nickel(I) dimer [(dtbpe)NiCl]2

Article abstract of DOI:10.1016/S0020-1693(02)01302-6

Tetrahydrofuran solutions of (dtbpe)NiCl₂ (dtbpe=1,2-bis(di-tert-butylphosphino)ethane) are reduced by KC₈ to afford the dimeric Ni(I) complex [(dtbpe)NiCl]₂ (1) in 73% yield. Reaction of 1 with [FeCp₂][PF₆] effects a one-electron oxidation to give the mixed-valent Ni(I,II) binuclear species [{(dtbpe)NiCl}₂][PF₆], [1][PF₆]. Complex 1 reacts with the radicals NO and TEMPO (2,2,6,6-tetramethyl-1-piperidine-N-oxyl) to give the diamagnetic Ni(0) nitrosyl (dtbpe)Ni(Cl)(NO) (2) and the Ni(II) complex (dtbpe)Ni(Cl)(O,N:η²-TEMPO) (3). Reduction of the S-S bond of diphenyldisulfide by 1 results in formation of the Ni(II) arylthiolate complex (dtbpe)NiCl(SPh) (4). The radical anions NaOCPh₂ and KN₂Ph₂ react cleanly with 1 to afford (dtbpe)Ni(η²-OCPh₂) (5) and (dtbpe)Ni(η²-N₂Ph₂) (6). Phenylacetylide C-C bond coupling is effected by reaction of 1 with LiC≡CPh to form [(dtbpe)Ni(C,C′:η²-CCPh)]₂ (7). In addition to standard spectroscopic (IR, NMR, EPR) and magnetic measurements, complexes 1, [1][PF₆], 3, and 5 were also characterized by single-crystal X-ray diffraction methods.

Full text of DOI:10.1016/S0020-1693(02)01302-6

Inorganica Chimica Acta 345 (2003) 299ꢂ308
/
www.elsevier.com/locate/ica
Synthesis of 1,2-bis(di-tert-butylphosphino)ethane (dtbpe) complexes
of nickel: radical coupling and reduction reactions promoted by the
nickel(I) dimer [(dtbpe)NiCl]2
Daniel J. Mindiola a, Rory Waterman a, David M. Jenkins b, Gregory L. Hillhouse a,*
a Department of Chemistry, Searle Chemistry Laboratory, The University of Chicago, Chicago, IL 60637, USA
b Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 USA
Received 13 June 2002; accepted 3 August 2002
Dedicated to our friend Professor Richard R. Schrock, an inspiring master of synthetic organometallic chemistry and catalysis
Abstract
Tetrahydrofuran solutions of (dtbpe)NiCl2 (dtbpeꢀ1,2-bis(di-tert-butylphosphino)ethane) are reduced by KC8 to afford the
/
dimeric Ni(I) complex [(dtbpe)NiCl]2 (1) in 73% yield. Reaction of 1 with [FeCp2][PF6] effects a one-electron oxidation to give the
mixed-valent Ni(I,II) binuclear species [{(dtbpe)NiCl}2][PF6], [1][PF6]. Complex 1 reacts with the radicals NO and TEMPO (2,2,6,6-
tetramethyl-1-piperidine-N-oxyl) to give the diamagnetic Ni(0) nitrosyl (dtbpe)Ni(Cl)(NO) (2) and the Ni(II) complex
(dtbpe)Ni(Cl)(O,N:h2-TEMPO) (3). Reduction of the SÃ
/
S bond of diphenyldisulfide by 1 results in formation of the Ni(II)
arylthiolate complex (dtbpe)NiCl(SPh) (4). The radical anions NaOCPh2 and KN2Ph2 react cleanly with 1 to afford (dtbpe)Ni(h2-
CPh to form
OCPh2) (5) and (dtbpe)Ni(h2-N2Ph2) (6). Phenylacetylide CÃ
/
C bond coupling is effected by reaction of 1 with LiCÅ
/
[(dtbpe)Ni(C,C?:h2-CCPh)]2 (7). In addition to standard spectroscopic (IR, NMR, EPR) and magnetic measurements, complexes 1,
[1][PF6], 3, and 5 were also characterized by single-crystal X-ray diffraction methods.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Crystal strcutures; Nickel complexes; Diphosphine complexes; Dimeric complexes
1. Introduction
interesting in that they offer the opportunity to study
and understand reactivity associated with an unusual
oxidation state. Monomeric Ni(I) complexes are ex-
pected to be paramagnetic (d9 electron configuration)
and to demonstrate redox properties unique to a Group
10 radical. Work in our laboratories has shown that
electron rich Ni(I) complexes can readily incorporate
hard ligands without reduction or disproportionation,
Well-defined Ni(I) complexes are relatively rare [1],
yet this unusual oxidation state has been invoked in
biologically relevant processes involving nickel-contain-
ing enzymes such as hydrogenase, carbon monoxide
dehydrogenase, and methyl-S-coenzyme M reductase
[2]. It is appreciated that the catalytic activity of these
nickel enzymes is dependent on redox processes invol-
ving the nickel center [2]. Isolation of homogeneous
complexes supporting the Ni(I) oxidation state are
affording excellent platforms for novel metalÃ
/ligand
multiple bonds [1n,q]. The use of bulky substituents on
the tertiary, chelating phosphorus ligand of 1,2-bis(di-
tert-butylphosphino)ethane (dtbpe) has allowed us to
develop a synthetic route to a stable Ni(I) chloride
complex and to explore its spectroscopic properties and
redox and substitution chemistry, topics presented in
this contribution.
* Corresponding author. Tel.: ꢁ
0805
E-mail address: g-hillhouse@uchicago.edu (G.L. Hillhouse).
/
1-773-702 7057; fax: ꢁ1-773-702
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 3 0 2 - 6

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2. Results and discussion
2.1. Synthesis and reactions of [(dtbpe)NiCl]2
Cold THF solutions of (dtbpe)NiCl2 react in a 1:1
stoichiometry with KC8 over a period of 2 h to afford
[(dtbpe)NiCl]2 (1) as large red blocks in 73% yield (Eq.
(1)). Related Ni(I) chloride dimers containing chelating
diphosphine ligands have been previously reported
[1l,n]. Complex 1 is soluble in most common organic
solvents such as benzene, Et2O, and THF, but only
sparingly soluble in alkanes. It exhibits reasonable
thermal stability in solution and in the solid-state, but
upon exposure to oxidants (e.g. O2) or halogenated
solvents (CH2Cl2) it gradually decomposes to myriad
products. In the solid-state, 1 is a dimer as shown by X-
ray crystallography (Fig. 1, Section 2.1.1). Temperature-
dependent solid-state magnetic susceptibility measure-
Fig. 2. SQUID data (circles) and calculated fit (line) for 1. Tempꢀ
10ꢂ255 K, Tmax 32 K; Jꢀ 2.25mB at 105 K; fit
35 cmꢃ1; mmax
with gꢀ2.05.
/
/
ꢀ/
/
ꢃ
/
ꢀ/
/
phosphorus nuclei (Fig. 3, Section 3.2.1). Although
paramagnetic, 1 shows relatively sharp resonances in
1
its H NMR spectrum (C6D6) which are easily assigned
to the tert-butyl and methylene groups on the dtbpe
ligand.
ments of a polycrystalline sample of 1 (SQUID, 10B
T B255 K) exhibited classic antiferromagnetic coupling
of the two d9 Ni centers (Tmax 35 cmꢃ1
32 K; Jꢀ
mmax 2.25mB at 105 K) illustrated in the plot of molar
/
/
ꢀ
/
/
ꢃ
/
,
ꢀ
/
susceptibility (xM) as a function of T shown in Fig. 2.
Solutions of 1 show an effective magnetic moment of
2.29mB per nickel, indicative of either dimer dissociation
to give a monomeric structure in solution, or a dimeric
structure in which the unpaired electrons are localized
on the two metal centers with negligible coupling. The
dimeric Ni(I) hydride [(dtbpe)Ni(m-H)]2, which has a
NiÃ
/
Ni bond, displays diamagnetic behavior in solution
[1r]. The molecular weight of 1 in THF solution (530
amu; avg of two trials), determined using the Signer
method, is most consistent with a monomeric solution
structure (monomer, 413 amu; dimer, 826 amu),
although a weak ion for the dimer can be detected in
an electrospray mass spectrum of 1 (824 [Mꢁ]). The
room temperature X-band EPR solution spectrum of 1
is a triplet with hyperfine coupling to 2 equivalent
Fig. 3. Room temperature X-band EPS spectrum of 1.
˚
Fig. 1. A perspective view of 1 with thermal ellipsoids at the 35% probability level. Selected bond lengths (A) and angles (8) are listed in Table 2.

D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ
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301
ð1Þ
[Cp2Fe][PF6] oxidizes 1 to the purple, paramagnetic
species [{(dtbpe)NiCl}2][PF6], [1][PF6], in good yield
(Scheme 1). Solution magnetic susceptibility measure-
ments are consistent with one unpaired electron for the
binuclear complex, and the room temperature solution
(THF) X-band EPR spectrum indicates one unpaired
electron localized about one of the NiP2 fragments (Fig.
4). Solid-state magnetic measurements (SQUID) showed
Curieꢂ
K with mavg
/
Weiss behavior for [1][PF6] between 60 and 300
1.96mB consistent with a mixed valence
Fig. 4. Room temperature X-band EPR spectrum of [1][PF6].
ꢀ
/
state dimer. The dimeric nature of [1][PF6] was con-
firmed by X-ray crystallography (Fig. 5, Section 2.1.2).
Mixed valent Ni(I)/Ni(II) species have been reported for
a series of cluster-type frameworks [3]. Complex [1][PF6]
is stable in the solid-state in the absence of oxidants.
However, CH2Cl2 solutions containing the dimer gra-
dually decompose over several days to a complex
mixture that includes several uncharacterized diamag-
netic products.
Treatment of 1 with 1 equiv./Ni of radicals such as
nitric oxide (NO) and TEMPO (2,2,6,6-tetramethyl-1-
piperidine-N-oxyl) affords the monomeric, diamagnetic,
and formally Ni(0) nitrosyl complex (dtbpe)NiCl(NO)
(2; 80% yield) and the monomeric, diamagnetic Ni(II)
complex (dtbpe)Ni(Cl)(O,N:h2-TEMPO) (3; 90% yield),
respectively (Scheme 1). Complexes 2 and 3 were
characterized by multinuclear NMR (1H, 13C, 31P) and
IR spectroscopies, and elemental analysis. The 1H NMR
spectrum of complex 2 shows two distinct sets of
doublets for the tert-butyl protons on the dtbpe ligand,
Fig. 5. A perspective view of [1][PF6] with thermal ellipsoids at the
˚
35% probability level. Selected bond lengths (A) and angles (8) are
listed in Table 2.
while the 31P NMR spectrum indicates 1 equivalent
phosphorus environment, data consistent with 2 posses-
sing pseudotetrahedral coordination geometry. The IR
spectrum of blue, crystalline 2 shows a strong n(NO) at
1734 cmꢃ1, a value similar to that found in other d10,
Ni(0) complexes containing linear nitrosyl ligands [4].
Ether solutions containing the TEMPO radical react
rapidly with 1 to afford purple solutions from which 3
can be isolated. NMR spectra (1H and 31P) indicate
inequivalent phosphorus nuclei, consistent with either
an h1-O-bound TEMPO ligand [5] or a complex having
an h2-O,N-bound TEMPO ligand (its most common
binding mode in metal complexes) [5,6] and a mono-
dentate dtbpe ligand in which one phosphine arm has
dissociated from nickel. In order to differentiate be-
tween these two possibilities, we determined the solid-
state molecular structure of 3 by single crystal X-ray
Scheme 1. Oxidation of 1 with 1 equivalent of [Cp2Fe][PF6] in cold
THF provides [1][PF6] as large purple blocks in 94% yield. Complex 1
couples with the radical NO in cold toluene solutions to afford 2 in
80% yield as large blue blocks. Addition of TEMPO to 1 in toluene
affords 3 in 90% yield as large purple blocks. Complex 1 slowly reduces
PhSSPh (24 h) in toluene to afford large brown blocks on 4 in 60%
yield.

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D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ308
/
diffraction methods and showed the latter structure with
a fully reduced, h2-O,N-bound TEMPO ligand to be the
correct one (Section 2.1.3).
Likewise, NMR spectra of 6 indicate a similar square-
planar geometry for this complex.
When an Et2O slurry of 1 is treated with LiCÅ
/
CPh, a
yellow solution results from which a complex (7) of the
empirical formula ‘(dtbpe)Ni(C2Ph)’ can be isolated in
94% yield (Scheme 2). We have prepared a variety of
‘three-coordinate’ Ni(I) alkyls supported by the dtbpe
ligand, and when the alkyl substituent is sufficiently
bulky, they are monomeric, paramagnetic d9 species
[10]. However, 7 is diamagnetic with two sets of
inequivalent dtbpe tert-butyl groups, two inequivalent
phosphorus environments (31P NMR), and an olefinic
stretch at 1589 cmꢃ1 in the infrared. Based on these
spectroscopic data and their similarity to those for
(dtbpe)Ni{C,C?:h2-C(Ph)C(H)} [11] and other h2-acet-
ylene complexes of Ni [12], we formulate 7 as an h2-
actetylene-coupled dimer, [(dtbpe)Ni(C,C?:h2-CCPh)]2
[13]. The dimer is probably formed from radical
coupling of the initial Ni(I) product of metathesis,
Addition of 1 equivalent of diphenyldisulfide to 1 in
toluene solution slowly effects reduction of the SÃ
/S
bond to afford the Ni(II) complex (dtbpe)NiCl(SPh) (4)
1
as dark brown blocks in 60% yield (Scheme 1). H and
31P NMR data are in accordance with a square-planar
Ni(II) complex containing mutually cis chloride and
phenylthiolato ligands, demonstrating the reducing
ability of Ni(I) complexes supported by electron rich
phosphine ligands. Analogous dichalcogenide bond
reductions by metalloradicals are known, for example,
in the chemistry of divalent lanthanides [7].
Treatment of 1 with the stable radical anions of
+ꢃ
+ꢃ
benzophenone (Ph2CO ) and azobenzene (Ph2N2
)
afforded the diamagnetic adducts (dtbpe)Ni(h2-OCPh2)
(5; 88% yield) and (dtbpe)Ni(h2-N2Ph2) (6; 84% yield),
respectively (Scheme 2) [8]. While it is common for
ketones and 1,2-disubstituted diazenes to react with
Ni(0) complexes to afford Ni(II) h2-adducts [9], sub-
stitution and radical coupling reactions effected by a
Ni(I) complex, analogous to those reported here, have
not been previously reported. The high reduction
potential of 1 suggests that both complexes 5 and 6
are likely generated by transmetallation and radical
coupling (or vice versa) rather than by reduction of Ni(I)
to Ni(0) via electron transfer followed by binding of the
neutral ketone or azobenzene. Complexes 5 and 6 were
characterized by multinuclear NMR (1H, 13C, 31P)
spectroscopy and elemental analysis. The 1H NMR
spectrum of 5 revealed equivalent phenyl groups on
the ketone ligand while the 31P NMR spectrum indi-
cated inequivalent phosphorus nuclei consistent with a
square-planar geometry about the nickel center. This
was confirmed by X-ray crystallography (Section 2.1.4).
(dtbpe)Ni(CÅ
/
CPh). It is noteworthy that we do not
observe (dtbpe)Ni(CÅ
/CPh)2 as a product in the reac-
tion, even though when not prohibited by sterics,
disproportionation of Ni(I) alkyls (i.e. LxNi(R)) to
Ni(II) bisalkyl complexes (LxNi(R)2) and ‘Ni(0)’ is
common [10].
2.1.1. Molecular structure determination of 1
Previous workers describing the synthesis of Ni(I)
halide complexes supported by chelate phosphines
speculated that such systems could be either monomeric
or dimeric in solution depending on the steric bulk of the
supporting phosphine [11]. X-ray structural analysis of 1
provided the first metrical parameters for a Ni(I) halide
complex supported by phosphines. Diffraction quality
crystals of 1 were grown from a dilute Et2O solution
cooled to ꢃ35 8C. A perspective view of 1 is shown in
/
Fig. 1. Table 1 gives crystal information and data
collection and refinement parameters for the structural
analysis. Selected bond distances and angles for 1 can be
found in Table 2.
The structure of 1 shows a binuclear Ni(I) species
bridged by chloride ligands. An inversion center about
the Ni2Cl2 centroid relates each metal fragment in the
complex giving the molecule D2h point symmetry. Each
nickel center adopts a pseudotetrahedral geometry with
the {P, Ni, P} and {Cl, Ni, Cl} planes being nearly
orthogonal. The NiÃ
/
ClÃ
/
Ni bridges are slightly asym-
metric, with NiÃCl distances of 2.3507(8) and 2.3858(8)
/
˚
A.
2.1.2. Molecular structure determination of [1][PF6]
Single violet plates of X-ray quality of complex
Scheme 2. Addition of cold THF solutions containing the radical
anion NaOCPh2 to 1 affords 5 in 96% yield, as orange plates.
Similarly, addition of 1 to cold THF solutions containing the radical
anion KN2Ph2 provides 6 as dark red plates in 84% yield. Metathesis
[1][PF6] can be readily grown at ꢃ35 8C from a
/
CH2Cl2 solution layered with Et2O. A molecular view
of [1][PF6] is shown in Fig. 5. It is interesting that
removal of one electron from pseudotetrahedral 1 forces
of 1 with LiCÅ
/
CPh in Et2O gives 7 in 94% yield as yellowꢂorange
/
blocks.

D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ
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303
Table 1
Crystallographic data
Compound
1
[1][PF6]
3
5
Empirical formula
Formula weight
Space group
C18H40ClNiP2
412.60
C2/c
C18H40ClF3NiP2.5
485.08
P21/c
C27H58ClNNiOP2
568.84
P21/c
C31H50NiOP2
559.36
C2/c
˚
a (A)
23.356(5)
16.378(4)
12.316(3)
114.762(4)
4278.2(16)
8
13.3329(9)
11.3782(8)
16.5264(12)
110.9020(10)
2342.1(3)
4
10.7705(11)
27.412(3)
11.2806(12)
111.434(2)
3100.2(6)
4
17.872(7)
16.253(7)
21.135(9)
101.131(8)
6024(4)
8
˚
b (A)
˚
c (A)
b (8)
3
V (A )
˚
Z
Dcalc (Mg mꢃ3
m (mmꢃ1
F(000)
)
1.281
1.178
1.376
1.137
1.219
0.834
1.234
0.772
)
1784
pale yellow
block
1030
violet
plate
1240
violet
needle
2416
orange
block
Crystal color, form
Crystal form
Crystal size (mm)
u Range (lattice, 8)
Index ranges
200ꢄ
1.57ꢂ28.37
305h 5
21, ꢃ165l 5
25 046
/
160ꢄ
/
80
300ꢄ
1.63ꢂ28.30
175h 5
215l 521
14 056
/
300ꢄ
/
40
210ꢄ
2.16ꢂ28.30
85h 514, ꢃ
155l 514
18 912
/
200ꢄ
/
100
80ꢄ
1.71ꢂ
185
20, ꢃ265
18 193
/
60ꢄ
28.44
h 5
l 5
/
20
/
/
/
/
ꢃ/
/
/30, ꢃ
/
215
/
k 5
/
ꢃ
ꢃ/
/
/
/17, ꢃ
/
155
/
k 5
/
6,
ꢃ
ꢃ/
/
/
/
/
355
/
k 5/34,
ꢃ/
/
/
23, ꢃ
/
215
/
k 5
/
/
/
/15
/
/
/
/
/
/
/
27
Reflections collected
Independent reflections
5164(0.0559)
5503(0.0454)
7240(0.0553)
7126(0.0834)
7126/0/316
a
(Rint
)
Data/restraints/para-
meters
5164/0/199
5503/0/233
7240/0/298
Final R indices [I ꢀ
/
R1ꢀ
/
0.0417, wR2ꢀ
/
0.0840 R1ꢀ
/
0.0432, wR2ꢀ
/
0.0972
R1ꢀ
/
0.0438, wR2ꢀ
/
0.0755
R1ꢀ
/
0.0802, wR2ꢀ
/
0.1767
c
2s(I)]
d
R indices (all data)
Goodness-of-fit on F2 b
R1ꢀ
1.115
0.557 and ꢃ
/
0.0525, wR2ꢀ
/
0.0880 R1ꢀ
1.164
0.695 and ꢃ
/
0.0477, wR2ꢀ
/
0.0999
R1ꢀ
0.876
0.616 and ꢃ
/
0.0668, wR2ꢀ
/
0.0810
R1ꢀ
1.092
1.305 and ꢃ0.555
/
0.1172, wR2ꢀ
/
0.3271
Largest difference peak
ꢃ3
/0.393
/0.406
/0.415
/
˚
and hole (e A
)
˚
100 K, Wavelengthꢀ0.71073 A. Refinement method: Full-matrix least-squares on
Common features to all crystals: monoclinic (aꢀ
/
gꢀ
/
908), Tꢀ
/
/
F2, Absorption correction: semi empirical from psi-scans.
a
b
c
2
2
Rintꢀ
Goodness-of-fitꢀ
/
a jFo2ꢃ
/
ŽFo j/a jFo j.
Sꢀ
[a [w(Fo2ꢃ
jFcjj/a jFoj.
[a [w(Fo2ꢃFc2)2]/a [w(Fo2)2]]1/2 for: wꢀ
q[s2(Fo2)ꢁ(aP)2ꢁ
/
/
/
Fc2)2]/(nꢃp)1/2
.
/
R1ꢀ
/
a jjFojꢃ
/
d
wR2ꢀ
/
/
/
q/s2(Fo2)ꢁ
/
(aP)2ꢁ
/
bP, nꢀ
/
number of independent reflections, pꢀ
/
number of parameters
refined, and weighting scheme wꢀ
/
/
/
bP]ꢃ1 where: Pꢀ
/
(Fo2ꢁ2Fc2)/3, aꢀ
/
/
, bꢀ, qꢀ1.
/
/
˚
the geometry of the nickel centers in [1][PF6] to shift to a
square-planar geometry. As in 1, the chlorides in
2.2881(7) and 2.3144(8) A) with the NiÃ
/
Cl bond lengths
˚
in [1][PF6] shorter by approximately 0.07 A than the
corresponding distances found in 1. Fig. 5 shows a
perspective view of the salt, with well-separated cations
and anions, in which the nickel centers are related by an
inversion center. Compiled crystallographic data for
[1][PF6] can be found in Table 1, and selected metrical
parameters for [1][PF6] can be found in Table 2.
[1][PF6] also bridge slightly asymmetrically (NiÃ
/
Clꢀ
/
Table 2
Select bond lengths (A) and angles (8) for 1 and [1][PF6]
˚
1
[1][PF6]
Bond lengths
NiÃ
NiÃ
NiÃ
NiÃ
/
P(2)
P(1)
Cl#1
Cl
2.2110(7)
2.2161(7)
2.3507(8)
2.3858(8)
2.2223(6)
2.2197(6)
2.3144(8)
2.2881(7)
2.1.3. Molecular structure determination structure of 3
A perspective view of the structure of 3 is shown in
Fig. 6 with pertinent bond distances and angles given in
the caption. Table 1 gives crystallographic parameters
associated with the structural analysis of 3. The most
noteworthy feature of the structure of 3 is the h2-
binding mode of the TEMPO ligand which results in
displacement of one arm of the dtbpe ligand. The
geometry about the nickel(II) is square-planar with
chloride trans to oxygen and with the O(1) Ni, N(1),
/
/
/
Bond angles
P(2)Ã
P(1)Ã
P(2)Ã
P(1)Ã
P(2)Ã
Cl#1Ã
Ni#1Ã
/
NiÃ
NiÃ
NiÃ
NiÃ
NiÃ
/
P(1)
Cl#1
Cl#1
Cl
91.98(3)
110.25(3)
131.78(3)
129.27(3)
110.30(3)
88.36(2)
91.60(2)
94.77(2)
166.32(3)
166.38(3)
95.18(3)
81.22(3)
98.78(3)
/
/
/
/
/
/
/
/Cl
/
NiÃ
/Cl
/
ClÃ
/Ni
91.64(2)
P(2), and Cl atoms nearly coplanar. The NiÃ
/N(1) bond

304
D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ308
/
Fig. 6. A perspective view of 3 with thermal ellipsoids at the 35%
˚
probability level. Selected bond lengths (A): NiÃ
O(1), 1.839(2); NiÃN(1), 1.926(2), O(1)ÃN(1), 1.385(2); NiÃ
2.1953(8). Selected angles (8): ClÃNiÃP(2), 99.35(3); N(1)ÃNiÃ
108.28(6); N(1)ÃNiÃO(1), 43.08(7); ClÃNiÃO(1), 151.36(6); O(1)ÃNiÃ
P(2), 109.19(5).
/
Cl, 2.1780(7); NiÃ
P(2),
Cl,
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Fig. 7. A perspective view of 5 with thermal ellipsoids at the 35%
˚
distance of 1.926(2) A is typical of a NiÃ
[1n] and the NiÃO(1) bond distance (1.839(2) A) is
similar to that observed in the oxametallacyclopropane
/
N single bond,
˚
probability level. Selected bond lengths (A): NiÃ
1.997(5); OÃC(7), 1.331(6); NiÃP(1), 2.199(2); NiÃ
Selected angles (8): OÃNiÃC(7), 40.31(17); P(1)ÃNiÃ
C(7)ÃNiÃP(2), 123.37(14); OÃNiÃP(1), 103.86(11).
/
O, 1.842(3); NiÃ
P(2), 2.170(2).
P(2), 92.46(6);
/
C(7),
˚
/
/
/
/
/
/
/
/
/
/
/
/
˚
moiety of 5 (1.842(3) A; Section 2.1.4).
were purchased from Acros or Fischer, stirred over
sodium metal, and filtered through activated alumina.
2.1.4. Molecular structure determination of 5
Compiled crystallographic data for 5 can be found in
Table 1. A perspective view of the structure is shown in
Fig. 7, and selected bond lengths and angles are listed in
the figure caption. The complex adopts a square-planar
Azobenzene was recrystallized from Et2O at ꢃ35 8C
/
prior to usage. KC8 and (dtbpe)NiCl2 were prepared
according to the literature [17,1r]. Phenylacetylene was
distilled under vacuum and filtered through alumina
geometry in which the ketone is bonded in an h2-fashion
prior to usage. LiCÅ
/
CPh was prepared by deprotona-
˚
C distance of 1.331(6) A demonstrates the
to Ni. The OÃ
/
tion of HCÅCPh with n-BuLi in hexanes at ꢃ
/
/
35 8C.
degree of reduction of the ketone versus that for free
˚
All other chemicals were used as received. IR data
(Fluorolube S-20 or Nujol mulls, CaF2 or KBr plates)
were measured with a Nicolet 670-FT-IR instrument.
Elemental analysis was performed by Desert Analytics
(Tucson, AZ). 1H, 13C, and 31P NMR spectra were
recorded on Bruker 500 and 400 MHz NMR spectro-
meters. 1H and 13C NMR data are reported with
reference to solvent resonances (residual C6D5H in
C6D6, 7.16 and 128.0 ppm; residual CHDCl2 in
CD2Cl2, 5.32 and 53.8 ppm). 31P NMR spectra were
reported with respect to external 85% H3PO4 (0 ppm).
Solution magnetic susceptibilities were determined by
the method of Evans [18,19]. Room temperature (r.t.) X-
band EPR spectra were recorded on a Bruker EMX
spectrometer.
SQUID measurements were performed on a Quantum
Designs SQUID magnetometer running MPMSR2 soft-
ware (Magnetic Property Measurement System Revision
2). Data were recorded at 5000 G. Samples were
suspended in the magnetometer in plastic straws sealed
under nitrogen with Lilly No. 4 gel caps. Loaded
samples were centered within the magnetometer using
the DC centering scan at 35 K and 5000 G. Data were
benzophenone (1.224ꢂ1.238 A) [14]. Similar ketone
/
complexes of nickel supported by phosphine ligands
have been prepared and structurally characterized [8].
The solid-state structure of 5 shows no other exceptional
features.
3. Experimental
3.1. General considerations
Unless otherwise stated, all operations were per-
formed in a M. Braun Lab Master dry box under an
atmosphere of purified nitrogen or using high-vacuum
and standard Schlenk techniques under an Ar atmo-
sphere [15]. Hexanes, petroleum ether, and C6H5CH3
were dried by passage through activated alumina and Q-
5 columns [16]. C6D6, and CD2Cl2 were purchased form
Cambridge Isotope Laboratory (CIL), degassed, and
˚
dried over CaH2 or activated 4 A molecular sieves.
˚
Celite, alumina, and 4 A molecular sieves were activated
under vacuum overnight at a temperature above
180 8C. Anhydrous solvents such as C6H6 and Et2O
acquired at 10ꢂ
/
20 (one data point per 2 K) and 20ꢂ255
/

D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ
/308
305
K (one data point per 5 K) for sample 1. Data were
collected at 60ꢂ300 K for [1][PF6] (one data point per 5
K).
3.2.2. Synthesis of [(dtbpe)NiCl]2[PF6] ([1][PF6])
To a ꢃ35 8C slurry of 1 (74 mg, 0.0897 mmol) in 6
ml of THF was added dropwise a cooled 4 ml THF
suspension of [FeCp2][PF6] (30 mg, 0.0897 mmol). The
stirred solution slowly turned purple in color. After 1.5 h
of stirring, the solution was filtered and pure crystals of
[1][PF6] were obtained by slow crystallization from a
/
/
The molar magnetic susceptibility (xM) was calculated
by converting the calculated magnetic susceptibility (x)
obtained from the magnetometer to a molar suscept-
ibility (using the multiplication factor {(molecular
weight)/[(sample weight)*(Field Strength)]}). The mag-
netic susceptibility was adjusted for diamagnetic con-
tributions using the constitutive corrections of Pascal’s
constants and a fixed temperature independent para-
THF/Et2O solution at ꢃ
/
35 8C (82 mg, 0.0845 mmol,
94% yield). H NMR (22 8C, 500.1 MHz, CD2Cl2): d
5.60 (br, Dn1/2 260 Hz, C(CH3)3, 36 H), ꢃ6.00 (br,
Dn1/2 280 Hz, CH2CH2, 4 H). IR (Nujol mull, KBr):
1178 (s), 1019 (m), 937 (s) 840 (s), 722 (w), 695 (w) 667
(w), 558 (m) 500 (m) cmꢃ1. meff
2.25mB (CD2Cl2, 298
K, Evans’ method). SQUID: 60BT B300 K; meff
(avg)ꢀ1.96mB (dimer). EPR (THF, 25 8C): giso 2.158,
Aiso 2, 100%), linewidth: 52 G, nꢀ
61 G (31P, nꢀ
9.751 GHz, pꢀ50.3 mW, MAꢀ1 G, MFꢀ100 kHz.
1
ꢀ
/
/
ꢀ
/
magnetism (TIP) crudely set to 1ꢄ
CurieꢂWeiss behavior was verified for [1][PF6] by a plot
of xꢃm 1 versus T. Data were analyzed using the following
relationships for [1][PF6]: xmꢀxM/mG; meff
(7.997xmT)1/2. These additional equations were used in
calculating the antiferromagnetism of 1: jJj/kTmax
1.599; xꢀ
2Ng2B2/(kT[3ꢁe(ꢃJ/kT)]).
/
10ꢃ4 cm3 molꢃ1
.
/
ꢀ
/
/
/
/
ꢀ
/
/
ꢀ
/
ꢀ
/
/
/
ꢀ
/
/
/
/
/
/
Anal. Calc. for C36H80F6Ni2P5: C, 44.6; H, 8.31. Found:
C, 44.0; H, 8.01%.
3.2. Synthetic protocols
3.2.3. Synthesis of (dtbpe)Ni(NO)Cl (2)
In a 100 ml Schlenk flask a solution of 1 (315 mg,
0.382 mmol) in 30 ml of C6H5CH3 was degassed and
3.2.1. Synthesis of [(dtbpe)NiCl]2 (1)
The following procedure is a slight modification and
complement to the protocol from our original commu-
nication [1n]. (dtbpe)NiCl2 (2.50 g, 5.58 mmol) was
dissolved in 100 ml of THF and the dark-red solution
cooled to ꢃ78 8C. Nitric oxide (19.62 ml, 1 atm, 2.10
/
equivalent) was added via syringe causing a rapid color
change to blue with precipitation of a blue solid. After
1.5 h the suspension was concentrated to half its original
volume and taken into the glovebox. The solution was
was cooled to ꢃ35 8C. To the Ni precursor solution
/
was added dropwise a suspension of KC8 (840 mg, 6.22
mmol) in 20 ml of cold THF, causing immediate
darkening of the solution and formation of graphite.
After stirring for 1.5 h the solution was filtered and the
then cooled to ꢃ35 8C for 2 h, filtered, and the blue
/
solid washed with Et2O, and dried under vacuum to
afford crude 2 (289 mg, 0.653 mmol, 86% yield). Large
blue blocks of 2 were grown from a CH2Cl2 solution
filtrate dried under reduced pressure. The redꢂ
/
orange
layered with excess Et2O, and cooled to ꢃ35 8C for 2
/
residue was extracted with approximately 160 ml of
C6H5CH3, filtered, and the solids washed with an
additional 40 ml of C6H5CH3. The filtrate was concen-
trated to approximately 25 ml and the solution cooled
days (270 mg, 0.611 mmol, 80% yield). 1H NMR
(22 8C, 500.1 MHz, CD2Cl2): d 2.15 (m, CH2CH2, 2
H), 1.86 (m, CH2CH2, 2 H), 1.35 (d, C(CH3)3, JHP
Hz, 18 H), 1.26 (d, C(CH3)3, JHP
ꢀ
/
12
12 Hz, 18 H).
ꢀ
/
and stored at ꢃ
/
35 8C for 1 day to afford large red
13C{1H} NMR (22 8C, 125.8 MHz, CD2Cl2): d 36.53
(bs, C(CH3)3), 36.05 (bs, C(CH3)3), 30.58 (s, C(CH3)3),
blocks of pure 1 (1.32 g, 1.62 mmol, 59%) in one crop.
The filtrate can be dried under vacuum and washed with
10 ml of cold petroleum ether/Et2O (3:1) to afford an
additional 316 mg of crude product (total yield, 73%).
30.11 (s, C(CH3)3), 21.84 (t, CH2CH2, JCP
ꢀ14 Hz).
/
31P{1H} NMR (22 8C, 202.4 MHz, CD2Cl2): d 92.66 (s,
P((C(CH3)3)2). IR (Fluorolube, CaF2): 2993(m),
2948(m), 2865(s), 1734(s, nNO), 1393(w), 1372(w),
1364(w) cmꢃ1. Anal. Calc. for C18H40ClNNiOP2: C,
48.8; H, 9.11; N, 3.16. Found: C, 48.8; H, 9.32; N,
3.09%.
1H NMR (22 8C, 400 MHz, C6D6): d 10.05 (br, Dn1/2
600 Hz, C(CH3)3, 36 H), ꢃ7.90 (br, Dn1/2 216 Hz,
CH2CH2, 4 H) ppm. IR (Fluorolube mull, CaF2):
ꢀ
/
/
ꢀ
/
2776(w), 2712(w), 1410(m), 1389(s), 1362(s) cmꢃ1
SQUID: 10BT B255 K; Tmax 32 K; Jꢀ
35 cmꢃ1
modeled with gꢀ2.05. Solution meff
.
;
/
/
ꢀ
/
/
ꢃ
/
/
ꢀ
/
2.29mB (per Ni
3.2.4. Synthesis of (dtbpe)Ni(Cl)(O,N:h2-TEMPO)
(3)
center, C6D6, 22 8C, Evans’s method). Solution mole-
cular weight measurement by the Signer method (THF):
To a ꢃ35 8C 5 ml C6H5CH3 solution of 1 (68 mg,
/
average MWꢀ
giso 2.141, Aiso
G, nꢀ9.766 GHz, pꢀ
kHz. M.p. (dec.) 230ꢂ
/
530 g molꢃ1. EPR (C6H5CH3, 25 8C):
0.082 mmol) was added dropwise a cold C6H5CH3
solution of TEMPO (26 mg, 0.165 mmol) causing a
rapid color change from pale orange to purple. The
solution was stirred for 1 h, filtered, and dried under
vacuum. The solid was extracted with Et2O, filtered,
ꢀ
/
ꢀ
/
73 G (31P, nꢀ
50.4 mW, MAꢀ
233 8C. Anal. Calc. for
/2, 100%), linewidth: 37
/
/
/
1 G, MFꢀ100
/
/
C36H80Cl2Ni2P4: C, 52.4; H, 9.77. Found: C, 52.4; H,
9.95%.
concentrated, and cooled to ꢃ35 8C for 1 day. Large
/

306
D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ308
/
purple blocks formed, which were filtered, washed with
cold petroleum ether, and dried under vacuum to afford
pure 3 (85 mg, 0.149 mmol, 90% yield). 1H NMR
crude 5 [151 mg, 0.254 mmol, 96% yield]. Large orange
blocks of pure 5 are obtained by dissolving the orange
powder in a minimum of CH2Cl2, filtering the solution,
layering carefully with excess Et2O, and cooling the
(22 8C, 500.1 MHz, C6D6): d 3.07 (s, ONÃ
(CH3)4C4H6, 6H), 2.24 (m, CH2CH2, 2H), 2.13 (m,
ONÃ2,2,6,6-(CH3)4C5H6, 2H), 1.77 (m, CH2CH2, 2H),
1.38 (d, C(CH3)3, JHP
13 Hz, 18H), 1.27 (m, ONÃ
2,2,6,6-(CH3)4C5H6, 2H), 1.26 (d, C(CH3)3, JHP 10
Hz, 18 H), 1.10 (m, ONÃ2,2,6,6-(CH3)4C5H6, 2H), 1.05
(s, ONÃ
2,2,6,6-(CH3)4C4H6, 6H). 13C{1H} NMR
(22 8C, 125.8 MHz, C6D6): d 37.48 (s, C(CH3)2),
34.07 (d, C(CH3)2, JCP 14 Hz), 32.88 (s, C(CH3)2),
31.79 (d, C(CH3)2, JCP 23 Hz), 30.03 (s, CH2), 29.92
(s, C(CH3)3), 23.71 (s, CH2), 22.39 (m, CH2CH2, JCP
13 Hz), 22.10 (d, CH2CH2, JCP 13 Hz), 19.28 (d,
C(CH3)2, JCP
23 Hz). 31P{1H} NMR (22 8C, 202.4
MHz, C6D6): d 52.27 (d, P(C(CH3)3)2, JPP 33 Hz),
37.65 (d, P(C(CH3)3)2, JPP 31 Hz). Anal. Calc. for
/
2,2,6,6-
layered solution to ꢃ35 8C for 2 days. The crystals and
/
/
solids were filtered, washed with Et2O, and dried under
ꢀ
/
/
vacuum to afford pure product (141 mg, 0.237 mmol,
1
88% yield). H NMR (22 8C, 500.1 MHz, CD2Cl2): d
7.93 (d, o-C6H5, 4 H), 7.15 (t, m-C6H5, 4 H), 7.06 (t, p-
ꢀ
/
/
/
C6H5, 2 H), 1.59 (m, CH2CH2, 4 H), 1.41 (d, C(CH3)3,
JHP
ꢀ
/
8 Hz, 18 H), 0.91 (d, C(CH3)3, JHP
ꢀ13 Hz, 18
/
ꢀ
/
H). 13C{1H} NMR (22 8C, 125.8 MHz, CD2Cl2): d
148.7 (s, aryl), 127.7 (s, aryl), 127.1 (s, aryl), 123.5 (s,
ꢀ
/
ꢀ
/
aryl), 34.80 (d, C(CH3)3, JCP
C(CH3)3), 30.71 (d, C(CH3)3, JPC
C(CH3)3, JCP 4 Hz), 24.92 (t, CH2CH2, JCP
20.04 (t, CH2CH2, JCP 13 Hz) (Note: The ketone
carbon resonance OCPh2 could not be located in the 13
NMR spectrum.). 31P{1H} NMR (22 8C, 202.4 MHz,
CD2Cl2): d 88.99 (d, P(C(CH3)3)2, JPP 66 Hz), 82.65
(d, P(C(CH3)3)2, JPP 66 Hz). Anal. Calc. for
ꢀ
/
12 Hz), 34.48 (bs,
4 Hz), 30.49 (d,
20 Hz),
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
C
C27H58ClNNiOP2: C, 56.3; H, 10.2; N, 2.52. Found: C,
56.7; H, 10.3; N, 2.22%.
ꢀ
/
ꢀ
/
3.2.5. Synthesis of (dtbpe)Ni(SPh)Cl (4)
In a vial was dissolved 1 (104 mg, 0.126 mmol) in 7 ml
C31H50NiOP2: C, 66.6; H, 9.01. Found: C, 66.4; H,
9.23%.
of C6H5CH3 and the solution cooled to ꢃ35 8C. To the
/
cold solution was added dropwise a cold C6H5CH3 (5
ml) solution containing diphenyldisulfide (28 mg, 0.126
mmol) causing a slow color change from pale orange to
brown. The solution was stirred for 24 h, filtered, and
dried under vacuum. The solids were extracted with a
minimum of CH2Cl2, filtered, layered with excess Et2O,
3.2.7. Synthesis of (dtbpe)Ni(h2-N2Ph2) (6)
KC8 (54 mg, 0.399 mmol) and PhNÄ/NPh (69 mg,
0.379 mmol) were mixed as solids in a 100 ml Schlenk
flask, and onto the solids was vacuum transferred
approximately 20 ml of dry THF at ꢃ
mixture was stirred for 2 h at ꢃ78 8C under N2 to
generate in situ the azobenzene radical anion (greenꢂ
/
78 8C. The
and cooled to ꢃ
/
35 8C overnight. Large brown blocks
/
form, which were filtered, washed with Et2O, and dried
under vacuum to afford 4 (78 mg, 0.150 mmol, 60%
/
brown solution with a black graphite precipitate). In a
separate 100 ml Schlenk flask equipped with a stir bar
was dissolved 1 (156 mg, 0.189 mmol) in 15 ml of THF.
1
yield). H NMR (22 8C, 500.1 MHz, CD2Cl2): d 7.48
(d, o-C6H5, 2H), 7.00 (t, m-C6H5, 2H), 6.93 (t, p-C6H5,
1H), 1.74 (m, CH2CH2, 4H), 1.56 (s, C(CH3)3, 18H),
1.55 (s, C(CH3)3, 18H). 13C{1H} NMR (22 8C, 125.8
MHz, CD2Cl2): d 144.2 (s, aryl), 135.2 (s, aryl), 127.1 (s,
aryl), 122.7 (s, aryl), 38.03 (bs, C(CH3)3), 31.04 (s,
C(CH3)3), 30.91 (s, C(CH3)3), 21.84 (bs, CH2CH2).
31P{1H} NMR (22 8C, 202.4 MHz, CD2Cl2): d 90.05
The pale orange solution was cooled to ꢃ
transferred via cannula (added slowly and dropwise) to
the radical anion mixture at ꢃ78 8C. After 1 h the
/
78 8C and
/
suspension was allowed to warm to r.t., stirred for an
additional 2 h, and taken into the glovebox. The
solution was filtered, extracted with C6H5CH3, and
dried under vacuum to afford crude 6 (206 mg, 0.368
mmol, 97% yield) as a dark red powder. Large red
blocks of 6 were obtained by extracting the solids with
C6H5CH3, filtrating the red solution, concentrating the
solution, adding 5 ml of Et2O, and cooling the solution
overnight. The crystals and solids were collected in three
crops, washed with cold Et2O, and dried under reduced
(bs, P(C(CH3)3)2, Dn1/2
ꢀ270 Hz), 81.84 (bs,
P(C(CH3)3)2, Dn1/2 30 Hz).
/
ꢀ
/
3.2.6. Synthesis of (dtbpe)Ni(h2-OCPh2) (5)
In a vial containing benzophenone (49 mg, 0.269
mmol) dissolved in 10 ml of THF was added small strips
of sodium metal (20 mg, 0.870 mmol) causing a slow
color change to purple. The solution was vigorously
1
pressure (178 mg, 0.318 mmol, 84% yield). H NMR
stirred for 4 h, filtered, cooled to ꢃ
dropwise to a cold THF (10 ml) solution containing 1
(110 mg, 0.134 mmol) causing a rapid color change to
/
35 8C, and added
(22 8C, 500.1 MHz, CD2Cl2): d 7.63 (d, o-C6H5, 4 H),
7.09 (t, m-C6H5, 4H), 6.82 (t, p-C6H5, 2H), 1.53 (bs),
0.85 (bs). 13C{1H} NMR (22 8C, 125.8 MHz, CD2Cl2):
d 159.1 (s, aryl), 128.7 (s, aryl), 122.5 (s, aryl), 120.2 (s,
aryl), 34.64 (bs, C(CH3)3), 30.86 (s, C(CH3)3), 22.20 (t,
brownꢂgreen. The reaction mixture was allowed to stir
/
for 2 h, filtered and dried under reduced pressure. The
solids were extracted with C6H5CH3, filtered to remove
a brown tar, and dried to give an orange powder of
CH2CH2, JCP
MHz, CD2Cl2): d 81.0 (s, P(C(CH3)3)2). Anal. Calc. for
ꢀ
/
16 Hz). 31P{1H} NMR (22 8C, 202.4

D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ
/308
307
C30H50N2NiP2: C, 64.4; H, 9.01; N, 5.01. Found: C,
64.7; H, 9.26; N, 4.73%.
3.4. EPR measurements
In a typical experiment a C6H5CH3 or THF solution
containing 1 or [1][PF6] (concentration ranging from 0.1
to 30 mM) were collected at 278 K. The magnitude of
3.2.8. Synthesis of [(dtbpe)Ni(C,C?:h2-CCPh)]2 (7)
the P (nꢀ2) coupling in 1 was found by simulation to be
/
To a cold (ꢃ
mg, 0.179 mmol) was added a 3 ml ether solution
containing LiCÅCPh (39 mg, 0.358 mmol). The solution
gradually turned yellowꢂorange and became homoge-
/
35 8C) 8 ml Et2O suspension of 1 (148
73 G and for [1][PF6] was 61 G, a value typical for Ni(I)
complexes bearing two phosphorus nuclei [1l,1n]. giso
values of 2.14 and 2.16 for 1 and [1][PF6], respectively,
also fall within reported results [21].
/
/
neous. After 24 h of stirring at r.t., the solution was
filtered, concentrated to 4 ml and cooled to give crystals
1
of 7 (160 mg, 0.169 mmol, 94%). H NMR (22 8C, 400
4. Conclusions
MHz, C6D6): d 7.64 (d, aryl, 2H), 7.27 (d, aryl, 2H),
6.96 (d, aryl, 1H), 1.59 (m, CH2CH2, 4H), 1.39 (d,
C(CH3), 9H), 1.29 (d, C(CH3), 9H), 1.04 (t, C(CH3),
18H). 13C{1H} NMR (22 8C, 125.8 MHz, C6D6): d
The dimeric nickel(I) complex 1 has been prepared
and characterized. Chemistry associated with complex 1
include its one electron oxidation to prepare the dimeric
cationic complex [1][PF6], radical coupling with NO and
TEMPO to afford the diamagnetic adducts 2 and 3,
145.2 (s, aryl), 132.6 (bs, C Ä
(s, aryl), 127.2 (s, aryl), 122.9 (s, aryl), 35.3 (s, C(CH3)3,
JCP 10 Hz), 34.3 (s, C(CH3)3, JCP 10 Hz), 33.8 (s,
/
C), 132.2 (bs, C Ä
/
C), 127.5
ꢀ
/
ꢀ
/
reduction of the SÃ/S bond of diphenyldisulfide to give
C(CH3)3, 31.3 (s, C(CH3)3, 31.0 (s, C(CH3)3, 30.2 (s,
C(CH3)3, 23.9 (m, CH2CH2), 22.6 (m, CH2CH2).
31P{1H} NMR (22 8C, 202.4 MHz, C6D6): d 96.6 (m,
the Ni(II) thiolato complex 4, and ligand metathesis
along with radical coupling to afford products 5, 6, and
7. The chemistry reported in this paper provides classic
examples of the rich redox chemistry offered by Ni(I).
P(C(CH3)3)2, JPP
1589 (s), 1304 (w), 1178 (s), 1019 (m), 952 (w), 847 (s),
ꢀ46, 21 Hz). IR (Nujol mull, KBr):
/
813 (w), 753 (m), 722 (m), 696 (w), 673 (w), 663 (w), 601
(w), 565 (w), 546 (w) cmꢃ1
. Anal. Calc. for
C52H90Ni2P4: C, 65.3; H, 9.48. Found: C, 64.6; H,
9.64%.
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 187549ꢂ187551, and 187553
/
3.3. Crystallographic structural determinations
for compounds 1, [1][PF6], 3, and 5, respectively. Copies
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
In a typical procedure a single crystal of 1, [1][PF6], 3,
or 5 was selected under a stereo-microscope while
immersed in Paratone oil to minimize possible reaction
with air. The crystal was removed from the oil using a
tapered fiber that also served to hold the crystal for data
collection. The crystal was mounted and centered on a
Bruker SMART APEX system. Rotation and still
images showed diffractions to be sharp. Frames sepa-
rated in reciprocal space were obtained and provided an
orientation matrix and initial cell parameters. Final cell
parameters were obtained from the full data set. A
hemisphere data set was obtained which samples
approximately 1.2 hemispheres of reciprocal space to a
1EZ, UK (fax: ꢁ44-1223-336-033; e-mail: deposit@
/
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
The deposited information contains atomic coordinates,
anisotropic displacement parameters, tables of bond
distances and angles, hydrogen coordinates, and torsion
angles. Structure factor tables may be obtained from the
authors.
Acknowledgements
˚
resolution of 0.84 A using 0.38 steps in v. Data
We are grateful to the National Science Foundation
for financial support of this research through a grant to
G.L.H. D.J.M. acknowledges postdoctoral fellowship
support from the Ford Foundation and the National
Institutes of Health. R.W. thanks the Department of
Education for a GAANN Fellowship, and D.M.J.
acknowledges the N.S.F. for a predoctoral fellowship.
Joshua Figueroa and Professor Karsten Meyer are
thanked for assistance in recording and simulating
EPR spectra, respectively.
collection was made at 100 K. Integration of intensities
and refinement of cell parameters were done using
SAINT. Absorption corrections were applied using psi-
scans. Observation after 5.5 h of data collection
suggested no decomposition of the crystal. Structures
were solved by direct methods using the SHELXTL
(version 5.1) program library [20]. Space groups were
based on systematic absences and intensity statistics and
hydrogen atoms were treated as idealized contributions.

308
D.J. Mindiola et al. / Inorganica Chimica Acta 345 (2003) 299ꢂ308
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[3] S. Fox, R.T. Stibrany, J.A. Potenza, H.J. Schugar, Inorg. Chim.
Acta 316 (2001) 122.
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