Alkyl transfer reactivity in the first octahedral isocyanide complex of nickel(II)

Article abstract of DOI:10.1021/om0343364

[Ni{S₂P(OEt)₂}₂] (1) reacts with 2 equiv of CNXyl (Xyl = 2,6-dimethylphenyl) to afford [Ni{S₂P(OEt) ₂}₂(CNXyl)₂] (2), which, as confirmed by X-ray crystallography, is the first octahedral isocyanide complex of Ni(II). Reaction of 2 with PCy₃ (2 equiv) produces square-planar [Ni{S ₂P(O)(OEt)}(PCy₃)(CNXyl)] (3). When 2 is reacted with only 1 equiv of PCy₃, the final product is the square-planar complex [Ni{S₂P(O)(OEt)}(CNXyl)₂] (4), containing two isocyanide ligands. Compound 4 reacts with 2-fold excess PCy₃ to give 3 via isocyanide displacement. Both 3 and 4 contain one ethyldithiophosphate ligand, which is produced by the transfer of one ethyl group from a coordinated diethyl dithiophosphate of complex 2 to the leaving diethyl dithiophosphate ligand. Experimental evidence indicates that the phosphine plays a significant role in the alkyl transfer. Moreover, reaction of 1 with 2 equiv of N-p-tolyl-2- iminopyridine affords octahedral [Ni{S₂P(OEt)₂}{2-pyCH= NC₆H₄-Me-4}₂][S₂P-(OEt) ₂] (5), in which both free and coordinated diethyl dithiophosphate coexist without any transfer of alkyl.

Full text of DOI:10.1021/om0343364

2568
Organometallics 2004, 23, 2568-2572
Alk yl Tr a n sfer Rea ctivity in th e F ir st Octa h ed r a l
Isocya n id e Com p lex of Nick el(II)
Enmanuel Bo´ıllos and Daniel Miguel*
Departamento de Qu´ımica Inorga´nica, Facultad de Ciencias, Universidad de Valladolid,
E-47005 Valladolid, Spain
Received December 1, 2003
[Ni{S2P(OEt)2}2] (1) reacts with 2 equiv of CNXyl (Xyl ) 2,6-dimethylphenyl) to afford
[Ni{S2P(OEt)2}2(CNXyl)2] (2), which, as confirmed by X-ray crystallography, is the first
octahedral isocyanide complex of Ni(II). Reaction of 2 with PCy3 (2 equiv) produces square-
planar [Ni{S2P(O)(OEt)}(PCy3)(CNXyl)] (3). When 2 is reacted with only 1 equiv of PCy3,
the final product is the square-planar complex [Ni{S2P(O)(OEt)}(CNXyl)2] (4), containing
two isocyanide ligands. Compound 4 reacts with 2-fold excess PCy3 to give 3 via isocyanide
displacement. Both 3 and 4 contain one ethyldithiophosphate ligand, which is produced by
the transfer of one ethyl group from a coordinated diethyl dithiophosphate of complex 2 to
the leaving diethyl dithiophosphate ligand. Experimental evidence indicates that the
phosphine plays a significant role in the alkyl transfer. Moreover, reaction of 1 with 2 equiv
of N-p-tolyl-2-iminopyridine affords octahedral [Ni{S2P(OEt)2}{2-pyCHdNC6H4-Me-4}2][S2P-
(OEt)2] (5), in which both free and coordinated diethyl dithiophosphate coexist without any
transfer of alkyl.
In tr od u ction
been done using N- or P-donor ligands.5 We wish to
report here the preparation of the first octahedral
isocyanide complex of nickel(II) and its reactivity with
phosphines, which involves a change in the coordination
number from 6 to 4, and simultaneous activation of a
O-C(alkyl) bond of the dithiophosphate ester.
The chemistry of nickel(II) isocyanide complexes is
dominated by the square-planar geometry. Only a few
examples of pentacoordinate Ni(II) complexes contain-
ing isocyanides have been reported, and most of them
are di- or polymetallic compounds where the pentaco-
ordination is attained by the formation of a direct
metal-metal bond.1 No report of structural character-
ization of a simple octahedral Ni(II) isocyanide complex
can be found in the Cambridge Structural Database and,
as far as we know, there has been no report on the
preparation of such complexes. This is remarkable, since
this class of complexes has attracted some interest in
several fields, such as the activation of CO2,2 the
polymerization of isocyanide catalyzed by Ni(II),3 and,
more recently, the preparation of N-aryl Ni(II) carbenes
from Ni(0) isocyanide complexes.4 Additionally, it is
well-known that bis(1,1-dithiolato)nickel(II) complexes
are able to add ligands to afford penta- or hexacoordi-
nate complexes, although most of these reactions have
Resu lts a n d Discu ssion
Addition of 2 mol equiv of CNXyl (Xyl ) 2,6-C6H6-
Me2) to a dichloromethane solution of [Ni{S2P(OEt)2}2]
(1)6 causes an immediate color change from purple to
red, and the IR monitoring indicates the coordination
of the isocyanide (ν(CN) 2181 cm-1 vs 2123 cm-1 for the
free ligand).7
The resulting complex 2 (Scheme 1) was isolated and
characterized by analytical and spectroscopic methods.
The octahedral environment around Ni was confirmed
by X-ray crystallography (Tables 1 and 2).
The molecule (Figure 1) is centrosymmetric, and the
two isocyanide ligands are trans to each other, which
is consistent with the appearance of only one ν(CN) band
in the IR spectrum. The coordination of the isocyanide
* To whom correspondence should be addressed. Tel: int + 34 983
184096. Fax: int + 34 983 423013. E-mail: dmsj@qi.uva.es.
(1) Kubiak, C. P. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press:
Oxford, U.K., 1995; Vol. 9, Chapter 1.
(2) DeLaet, D. L.; del Rosario, R.; Fanwick, P. E.; Kubiak, C. P. J .
Am. Chem. Soc. 1987, 109, 754. DeLaet, D. L.; Fanwick, P. E.; Kubiak,
C. P. J . Chem. Soc., Chem. Commun. 1987, 1412. Lemke, F. R., DeLaet,
D. L.; Gao, J .; Kubiak, C. P. J . Am. Chem. Soc. 1988, 110, 6904.
(3) Deming, T. J .; Novak, B. M. J . Am. Chem. Soc. 1992, 114, 4400,
7296; 1993, 115, 9101. Visser, H. G. J .; Nolte, R. J . M.; Zwikker, J .
W.; Drenth, W. J . Org. Chem. 1985, 50, 3133, 3138. Amabilino, D. B.;
Ramos, E.; Serrano, J . L.; Veciana, J . Adv. Mater. 1998, 10, 1001.
Amabilino, D. B.; Ramos, E.; Serrano, J . L.; Sierra, T.; Veciana, J . J .
Am. Chem. Soc. 1998, 120, 9126.
(5) Sacconi, L.; Mani, F.; Bencini, A. In Comprehensive Coordination
Chemistry; Wilkinson, G., Guillard, R. D., McCleverty, J . A., Eds.;
Pergamon Press: Oxford, U.K., 1987; Vol. 5, Chapter 50.
(6) Coldbery, D. E.; Fernelius, W. C.; Shamma, M. Inorg. Synth.
1960, 6, 142.
(7) One reviewer asked for an explanation: when isocyanides are
coordinated to a monopositive or dipositive metal ion such as Cr(0) or
Ni(0), little or no back-donation occurs, and the CN stretching band is
shifted to a higher frequency as a result of the inductive effect of the
metal. When isocyanides are coordinated to zero-valent metals, back-
donation is extensive and the CN stretching band is shifted to lower
frequency. See: Nakamoto, K. Infrared and Raman Spectra of Inor-
ganic and Coordination Compounds, 5th ed.; Wiley: New York, 1997;
Part B (Applications in Coordination, Organometallic, and Bioinorganic
Chemistry), p 115. Cotton, F. A.; Zingales, F. J . Am. Chem. Soc. 1961,
83, 351.
(4) Hou, H.; Gantzel, P. K.; Kubiak, C. P. J . Am. Chem. Soc. 2003,
125, 9564. Hou, H.; Gantzel, P. K.; Kubiak, C. P. Organometallics 2003,
22, 2817.
10.1021/om0343364 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 04/14/2004

The First Octahedral Isocyanide Complex of Ni(II)
Organometallics, Vol. 23, No. 11, 2004 2569
Ta ble 1. Cr ysta l Da ta a n d Refin em en t Deta ils for [Ni{S2P (OEt)2}2(CNXyl)2] (2),
[Ni{S2P (O)(OEt)}(CNXyl)(P Cy3)] (3), [Ni{S2P (O)(OEt)}(CNXyl)2] (4), a n d
[Ni{S2P (OEt)2}{2-p yCHdNC6H4-Me-4}2][S2P (OEt)2] (5)
2
3
4
5
formula
fw
C
26H38N2NiO4P2S4
C
29H47NNiO2P2S2‚CH2Cl2
C
20H23N2NiO2PS4
C
34H44N4NiO4P2S4
691.47
711.37
477.20
821.62
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
triclinic
P1h (No. 2)
10.911(3)
10.932(3)
14.640(4)
101.227(4)
90.509(5)
96.954(4)
1699.1(8)
2
monoclinic
P21/c (No. 14)
16.522(1)
13.903(1)
15.309(1)
90
90.104(2)
90
3516.5(4)
4
monoclinic
C2/c (No. 15)
15.406(5)
13.201(4)
22.338(7)
90
102.738(6)
90
4431(2)
8
triclinic
P1h (No. 2)
11.657(6)
13.101(7)
15.337(8)
98.199(9)
109.12(1)
110.843(9)
1977(2)
2
T, K
293
1.352
724
293
1.344
1504
293
1.431
1984
293
1.380
860
F
calcd, g cm-3
F(000)
λ(Mo KR), Å
0.710 73
0.28 × 0.18 × 0.12;
pale green
0.943
0.710 73
0.22 × 0.21 × 0.17;
yellow
0.710 73
0.14 × 0.08 × 0.06;
orange
0.710 73
0.23 × 0.14 × 0.08;
orange
cryst size, mm; color
µ, mm-1
0.941
1.154
0.824
scan range, deg
abs cor
1.42 e θ e 23.5
SADABS
1.0000, 0.8020
10 582
4825
4020
1.23 e θ e 23.29
SADABS
1.000, 0.8673
15 501
5065
4096
1.87 e θ e 23.28
SADABS
1.000, 0.4403
9703
3186
1683
1.47 e θ e 23.32
SADABS
1.000, 0.6629
8722
5541
3476
corrn factors (min, max)
no. of rflns measd
no of indep rflns
no of rflns with I e 2σ(I)
GOF on F2
1.007
1.026
1.003
1.003
no. of params
363
364
258
449
residuals R1, wR2
0.0595, 0.1907
0.0398, 0.1228
0.0514, 0.0812
0.0563, 0.1348
Sch em e 1
been lost to give O-ethyl dithiophosphate. As outlined
in Scheme 1, complex 3 can also be obtained by reacting
1 successively with 1 equiv of PCy3 and 1 equiv of
isocyanide (see Experimental Section).
Surprisingly, when the octahedral bis(isocyanide)
complex 2 was reacted with only 1 equiv of phosphine,
the resulting compound retained the two isocyanide
ligands, and the phosphine was not incorporated, thus
affording compound 4. Although the phosphine was
absent from the final product, its presence in the
reaction mixture seems to be necessary, since complex
2 does not transform into 4 even in the presence of
excess isocyanide.
Compound 4 undergoes replacement of isocyanide by
phosphine, and the complete transformation from 4 to
3 can be achieved by using a 2-fold excess of PCy3. In
contrast, complex 3 does not react even in the presence
of excess isocyanide in refluxing toluene for several
hours.
As was the case with compound 3, an X-ray determi-
nation (Figure 3 and Table 4) confirmed that in 4 the
Ni atom lies in a square-planar four-coordinate environ-
ment, and again one ethyl group of the dithiophosphate
ligand has been lost.
There are only a few precedents for this O-C activa-
tion in Ni(II)9 and Mo(V)10 complexes, and its relevance
in several fields has been recently emphasized, espe-
cially in connection with the enzymatic alkyl transfer
from and to phosphate esters.10,11 It has been generally
proposed that the alkyl group is transferred to the
leaving dithiophosphate group to afford neutral O,O′,S-
triethyl dithiophosphate: EtSP(dS)(OEt)2.
ligands in 2 is weaker than in the square-planar
complexes (cf. Ni-C distances and ν(CN) bands for 2
with those of 3 and 4 below). In the equatorial plane,
the Ni atom and the two dithiolato ligands are arranged
in a fashion very close to that found in the structural
determination8 of the square-planar starting compound
1.
Upon addition of 2 equiv of phosphine, complex 2
slowly undergoes transformation into the new species
3, in which one phosphine is incorporated into the
coordination sphere of Ni, replacing one dithio ligand
and one isocyanide, thus affording a four-coordinate
square-planar complex. This has been confirmed by
X-ray crystallography for 3 (Figure 2 and Table 3).The
structure determination revealed also that one ethyl
group of the remaining coordinated dithio ligand had
(9) Gastaldi, L.; Porta, P.; Tomlison, A. A. G. J . Chem. Soc., Dalton
Trans. 1974, 1424.
(10) Koffi-Sokpa, E. I.; Calfee, D. T.; Allred, B. R. T.; Davis, J . L.;
Haub, E. K.; Rich, A. K.; Porter, R. A.; Mashuta, M. S.; Richardson, J .
F.; Noble, M. E. Inorg. Chem. 1999, 38, 802.
(8) Fernando, Q.; Green, C. D. J . Inorg. Nucl. Chem. 1967, 29, 647.
(11) Wilker, J . J .; Lippard, S. J . Inorg. Chem. 1997, 36, 969.

2570 Organometallics, Vol. 23, No. 11, 2004
Bo´ıllos and Miguel
Ta ble 2. Selected In ter a tom ic Dista n ces (Å) a n d An gles (d eg) in [Ni{S2P (OEt)2}2(CNXyl)2] (2)a
Ni(1)-C(1)#1
Ni(1)-S(2)#1
Ni(1)-S(1)
2.006(7)
2.5185(19)
2.5564(19)
1.986(3)
1.585(5)
1.164(8)
2.020(6)
2.5221(18)
2.5324(19)
1.982(3)
1.602(6)
1.151(8)
Ni(1)-C(1)
2.006(7)
2.5185(19)
2.5564(19)
1.979(2)
1.612(5)
1.403(8)
2.020(6)
2.5221(18)
2.5324(19)
1.985(3)
1.607(6)
1.419(8)
Ni(1)-S(2)
Ni(1)-S(1)#1
S(1)-P(1)
P(1)-O(1)
N(1)-C(2)
Ni(51)-C(51)#2
Ni(51)-S(51)#2
Ni(51)-S(52)#2
S(52)-P(51)
P(51)-O(51)
N(51)-C(52)
S(2)-P(1)
P(1)-O(2)
C(1)-N(1)
Ni(51)-C(51)
Ni(51)-S(51)
Ni(51)-S(52)
S(51)-P(51)
P(51)-O(52)
C(51)-N(51)
C(1)#1-Ni(1)-C(1)
C(1)-Ni(1)-S(2)#1
C(1)-Ni(1)-S(2)
180.0(3)
88.23(18)
C(1)#1-Ni(1)-S(2)#1
C(1)#1-Ni(1)-S(2)
S(2)#1-Ni(1)-S(2)
C(1)-Ni(1)-S(1)
91.77(18)
88.23(18)
180.0
91.77(18)
89.27(17)
98.75(6)
90.73(17)
81.25(6)
180.000(1)
180.0
88.99(17)
91.01(17)
180.0
C(1)#1-Ni(1)-S(1)
S(2)#1-Ni(1)-S(1)
C(1)#1-Ni(1)-S(1)#1
S(2)#1-Ni(1)-S(1)#1
S(1)-Ni(1)-S(1)#1
S(52)-Ni(51)-S(52)#2
C(51)-Ni(51)-S(51)
C(51)-Ni(51)-S(51)#2
S(51)-Ni(51)-S(51)#2
C(51)#2-Ni(51)-S(52)
S(51)#2-Ni(51)-S(52)
N(51)-C(51)-Ni(51)
90.73(17)
81.25(6)
89.27(17)
98.75(6)
176.5(6)
180.00(15)
91.01(17)
88.99(17)
90.68(18)
81.81(6)
89.32(18)
98.19(6)
S(2)-Ni(1)-S(1)
C(1)-Ni(1)-S(1)#1
S(2)-Ni(1)-S(1)#1
C(1)-N(1)-C(2)
C(51)-Ni(51)-C(51)#2
C(51)#2-Ni(51)-S(51)
C(51)#2-Ni(51)-S(51)#2
C(51)-Ni(51)-S(52)
S(51)-Ni(51)-S(52)
C(51)-Ni(51)-S(52)#2
S(51)-Ni(51)-S(52)#2
89.32(18)
98.19(6)
177.4(5)
a
Symmetry transformations: (#1) -x, -y, -z + 1; (#2) -x + 1, -y + 1, -z + 2.
Ta ble 3. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) in [Ni{S2P (O)(OEt)}(CNXyl)(P Cy3)] (3)
Ni(1)-C(1)
Ni(1)-P(1)
S(1)-P(2)
P(1)-C(31)
P(1)-C(21)
P(2)-O(2)
1.820(4)
2.2166(9)
2.0371(12)
1.846(3)
1.851(3)
1.588(3)
Ni(1)-S(1)
Ni(1)-S(2)
S(2)-P(2)
P(1)-C(41)
P(2)-O(1)
N(1)-C(1)
2.1855(9)
2.2248(10)
2.0357(13)
1.846(3)
1.460(2)
1.151(4)
C(1)-Ni(1)-S(1)
S(1)-Ni(1)-P(1)
S(1)-Ni(1)-S(2)
P(2)-S(1)-Ni(1)
173.40(11) C(1)-Ni(1)-P(1)
95.59(10)
86.25(11)
176.36(4)
87.60(4)
91.00(3)
87.15(4)
88.64(4)
C(1)-Ni(1)-S(2)
P(1)-Ni(1)-S(2)
P(2)-S(2)-Ni(1)
C(31)-P(1)-C(41) 105.11(14) C(31)-P(1)-C(21) 110.91(16)
C(41)-P(1)-C(21) 103.66(14) C(31)-P(1)-Ni(1) 112.05(11)
C(41)-P(1)-Ni(1) 109.74(11) C(21)-P(1)-Ni(1) 114.59(11)
O(1)-P(2)-O(2)
O(2)-P(2)-S(2)
O(2)-P(2)-S(1)
C(1)-N(1)-C(2)
106.56(15) O(1)-P(2)-S(2)
108.94(12) O(1)-P(2)-S(1)
108.84(12) S(2)-P(2)-S(1)
118.87(12)
116.55(12)
96.56(5)
F igu r e 1. Perspective view of one of the two crystallo-
graphically independent but chemically equivalent mol-
ecules of [Ni{S2P(OEt)2}2(CNXyl)2] (2), showing the atom
numbering. The numbering of the second molecule can be
obtained by adding 50 to the number in the label.
176.0(4)
S(2)-P(2)-S(1)
96.56(5)
necessarily to the transference of alkyl. Thus, the bis-
(dithiophosphate) complex 1 reacts with 2 equiv of N-p-
tolyl-2-iminopyridine, as depicted in Scheme 2, to afford
the salt 5, via displacement of the O,O′ dithiophosphate
anion.
An X-ray determination reveals that 5 contains both
coordinated and free dithiophosphate, without any
transfer of alkyl (Figure 4 and Table 5).
F igu r e 2. Perspective view of the molecule of [Ni{S2P-
(O)(OEt)}(CNXyl)(PCy3)] (3), showing the atom numbering.
However, there are several experimental facts which
suggests a more complex mechanism. In the first place,
the presence of a leaving dithiophosphate does not lead
F igu r e 3. Perspective view of the molecule of [Ni{S2P-
(O)(OEt)}(CNXyl)2] (4), showing the atom numbering.

The First Octahedral Isocyanide Complex of Ni(II)
Organometallics, Vol. 23, No. 11, 2004 2571
Ta ble 4. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) in [Ni{S2P (O)(OEt)}(CNXyl)2] (4)
Ni(1)-C(1)
Ni(1)-S(1)
S(1)-P(1)
P(1)-O(1)
N(1)-C(1)
N(2)-C(2)
1.821(7)
2.1887(17)
2.023(2)
1.451(4)
1.148(7)
1.149(6)
Ni(1)-C(2)
Ni(1)-S(2)
S(2)-P(1)
P(1)-O(2)
N(1)-C(11)
N(2)-C(21)
1.831(6)
2.1894(19)
2.032(2)
1.585(5)
1.399(7)
1.393(7)
C(1)-Ni(1)-C(2)
C(2)-Ni(1)-S(1)
C(2)-Ni(1)-S(2)
P(1)-S(1)-Ni(1)
O(1)-P(1)-O(2)
O(2)-P(1)-S(1)
O(2)-P(1)-S(2)
C(1)-N(1)-C(11) 177.9(6)
C(3)-O(2)-P(1) 122.8(4)
N(2)-C(2)-Ni(1) 176.7(6)
96.4(2)
175.5(2)
88.39(18) S(1)-Ni(1)-S(2)
87.72(8)
106.0(3)
108.64(19) O(1)-P(1)-S(2)
109.68(19) S(1)-P(1)-S(2)
C(1)-Ni(1)-S(1)
C(1)-Ni(1)-S(2)
87.96(18)
171.2(2)
87.45(7)
87.47(8)
118.1(2)
P(1)-S(2)-Ni(1)
O(1)-P(1)-S(1)
117.5(2)
96.53(9)
F igu r e 4. Perspective view of the molecule of [Ni{S2P-
(OEt)2}{2-pyCHdNC6H4-Me-4}2][S2P(OEt)2] (5), showing
the atom numbering.
C(2)-N(2)-C(21) 177.0(6)
N(1)-C(1)-Ni(1) 174.2(6)
O(2)-C(3)-C(4)
Sch em e 2
110.2(7)
Ta ble 5. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) in
[Ni{S2P (OEt)2}{2-p yCHdNC6H4-Me-4}2][S2P (OEt)2]
(5)
Ni(1)-N(1)
Ni(1)-N(2)
Ni(1)-S(2)
S(1)-P(1)
P(1)-O(1)
N(1)-C(11)
N(2)-C(16)
N(3)-C(31)
N(4)-C(36)
2.084(5)
2.095(4)
2.4403(19)
1.933(3)
1.5057
1.322(7)
1.282(7)
1.331(7)
1.257(7)
Ni(1)-N(4)
Ni(1)-N(3)
Ni(1)-S(1)
S(2)-P(1)
P(1)-O(2)
N(1)-C(15)
N(2)-C(17)
N(3)-C(35)
N(4)-C(37)
2.090(4)
2.110(5)
2.468(2)
1.968(3)
1.527(6)
1.353(7)
1.432(7)
1.343(7)
1.429(7)
In an early related precedent, the structure of [Ni-
{S2P(OMe)2}2(phen-Me2)] contains both monodentate
and bidentate dithiophosphate, again without any alkyl
transfer between them.12 Interestingly, the octahedral
bis(isocyanide) complex 2 does not react with an excess
of diimine, even in refluxing THF for several hours.
The experimental results known so far indicate that
the transfer of alkyl occurs only when phosphine is
present in the reaction mixture, even in the case
(formation of 4) when the phosphine is not incorporated
into the final product.
N(1)-Ni(1)-N(4)
N(4)-Ni(1)-N(2)
N(4)-Ni(1)-N(3)
N(1)-Ni(1)-S(2)
N(2)-Ni(1)-S(2)
N(1)-Ni(1)-S(1)
89.92(18) N(1)-Ni(1)-N(2)
78.11(18)
90.57(16) N(1)-Ni(1)-N(3) 164.03(17)
78.36(19) N(2)-Ni(1)-N(3) 91.06(18)
93.08(13) N(4)-Ni(1)-S(2) 174.83(14)
94.16(12) N(3)-Ni(1)-S(2)
99.56(14) N(4)-Ni(1)-S(1)
99.46(14)
92.80(13)
91.89(13)
91.89(13)
N(2)-Ni(1)-S(1) 175.90(13) N(3)-Ni(1)-S(1)
S(2)-Ni(1)-S(1)
82.55(6)
N(3)-Ni(1)-S(1)
experimental procedures have been given elsewhere.14 Litera-
ture procedures for the preparation of starting materials are
quoted in each case. Ligands and other reagents were pur-
chased and used without purification, unless otherwise stated.
[Ni{S2P (OEt)2}(CNXyl)2] (2). To a solution of 1 (0.214 g,
0.5 mmol)6 in CH2Cl2 (20 mL) was added 2,6-dimethylphenyl
isocyanide (CNXyl; 0.131 g, 1 mmol), and the mixture was
stirred for 0.5 h at room temperature. The color changed from
purple to deep red. The solvent was evaporated, and the
residue was washed several times with hexane. The solid was
dissolved in the minimum amount of CH2Cl2 and layered with
hexane. Slow diffusion at -20 °C afforded compound 2 as green
crystals. Yield: 0.048 g, 69%. Anal. Calcd for C26H38N2-
NiO4P2S4: C, 45.16; H, 5.54; N, 4.05. Found: C, 44.93; H, 5.28;
Additionally, IR monitoring of the reaction mixtures
of 1 and 2 with PCy3/isocyanide reveals the formation,
in the initial steps, of the complex [Ni(CNXyl)4], as
deduced from the ν(CN) bands at 2030 and 2000 cm-1
,
identical with those of an authentic sample prepared
as described in the literature.13 The Ni(0) complex
slowly transforms into the final products 3 and 4,
depending on the amount of phosphine available. This
implies that some reduction and oxidation processes are
involved in the mechanism. On the other hand, the
monitoring of the crude reaction mixtures by 31P{1H]}
NMR shows the presence of EtSP(dS)(OEt)2 (at δ 96.1
ppm), together with small amounts of phosphine sulfide
and phosphine oxide, and no trace of the signal of [PCy3-
Et]+, suggesting that the phosphine activates the pro-
cess through coordination to the metal atom in an
intermediate, rather than being involved directly in the
alkyl transfer. Some work is now in progress attempting
to obtain conclusive information about the mechanism
of this interesting C-O activation.
N, 4.09. IR (CH2Cl2): ν(CN) 2181 cm-1. H NMR (Me2CO-d6;
1
δ (ppm)): 8.12 (t(7), 2H, H4 of Xyl), 6.71 (d(7), 4H, H3and H5of
Xyl), 4.37 (m (br), 8H, POCH2), 1.72 (m (br), 12H, POCH2CH3),
1.44 (s, 12H, CH3 of Xyl). 31P{1H} NMR (δ (ppm)): 78 (v br).
[Ni{S2P (O)(OEt)}(CNXyl)(P Cy3)] (3). (a ) F r om 1. To a
purple solution of 1 (0.214 g, 0.5 mmol)6 in CH2Cl2 (20 mL)
was added PCy3 (0.28 g, 1 mmol), and the solution turned
green. After the solution was stirred for 1 h, CNXyl (0.065 g,
0.5 mmol) was added and the solution turned red immediately.
The mixture was stirred for 5 h, and then the solvent was
evaporated in vacuo. The residue was washed with Et2O to
extract a small amount of starting 1. The resulting solid was
redissolved in CH2Cl2 and filtered. Addition of hexane followed
by slow evaporation gave yellow crystals of 3‚CH2Cl2. Yield:
0.302 g, 85%. Anal. Calcd for C29H47NNiO2P2S2‚CH2Cl2: C,
50.65; H, 6.94; N, 1.97. Found: C, 50.33; H, 6.81; N, 1.83. IR
Exp er im en ta l Section
All reactions were carried out in dry solvents under a
nitrogen atmosphere. Details of the instrumentation and
(12) Tomlison, A. A. G.; Furlani, C. J . Chem. Soc., Dalton Trans.
1974, 1420.
(13) Kim, W. Y.; Chang, J . S.; Park, S. E.; Kubiak, C. P. Res. Chem.
Intermed. 1999, 25, 459.
(14) Barrado, G.; Hricko, M. M.; Miguel, D.; Riera, V.; Wally, H.;
Garc´ıa-Granda, S. Organometallics 1998, 17, 820.

2572 Organometallics, Vol. 23, No. 11, 2004
Bo´ıllos and Miguel
1
(CH2Cl2): ν(CN) 2151 cm-1. H NMR (CDCl3; δ (ppm)): 7.23
hexane (3 × 10 mL). The resulting solid was recrystallized
from CH2Cl2/hexane to obtain orange crystals of 5. Yield:
0.275, 67%. Anal. Calcd for C34H44N4NiO4P2S4: C, 49.70; H,
5.40; N, 6.82. Found: C, 49.63; H, 5.18; N, 6.51.
(t(7), 1H, H4 of Xyl), 7.12 (d(7), 2H, H3and H5of Xyl), 4.08 (m
(br), 2H, POCH2), 2.42 (s, 6H, CH3 of Xyl), 2.07 to 1.25 (m,
33H, Cy), 1.33 (m, 3H, POCH2CH3). 31P{1H} NMR δ 56.9
(d(12), S2PO), 42.5 (d(12), PCy3).
(b) F r om 2. To a solution of 2 (0.346 g, 0.5 mmol) in CH2-
Cl2 (15 mL) was added PCy3 (0.28 g, 1 mmol), and the mixture
was stirred at room temperature for 30 h. The solvent was
evaporated to dryness, and the residue was washed with Et2O
(2 × 5 mL). The solid was recrystallized from CH2Cl2/hexane.
Yield: 0.26 g, 73%.
(c) F r om 4. To a solution of 4 (0.24 g, 0.5 mmol) (see below)
in CH2Cl2 (15 mL) was added PCy3 (0.28 g, 1 mmol), and the
mixture was stirred at room temperature for 24 h. The solvent
was evaporated to dryness, and the residue was washed with
Et2O (2 × 5 mL). The solid was recrystallized from CH2Cl2/
hexane. Yield: 0.293 g, 80%.
X-r a y Diffr a ction Stu d ies. Crystals were grown by slow
diffusion of hexane into concentrated solutions of the com-
plexes in CH2Cl2 at -20 °C. Relevant crystallographic details
are given in Table 1. Intensity measurement was made with
a Bruker AXS SMART 1000 diffractometer with graphite-
monochromated Mo KR X-radiation and a CCD area detector.
A hemisphere of the reciprocal space was collected up to 2θ )
48.6°. Raw frame data were integrated with the SAINT15
program. The structures were solved with SHELXTL.16
A
semiempirical absorption correction was applied with the
program SADABS.17 All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were set in calculated posi-
tions and refined as riding atoms, with a common thermal
parameter. All calculations and graphics were made with
SHELXTL.
[Ni{S2P (O)(OEt)}(CNXyl)2] (4). To a red solution of 2
(0.345 g, 0.5 mmol) in CH2Cl2 (20 mL) was added PCy3 (0.14
g, 0.5 mmol), and the mixture was stirred at room temperature
for 10 h. The color changed slowly to red-brown. The solvent
was evaporated in vacuo, the residue was washed with hexane
and redissolved in CH2Cl2/hexane (1/1, v/v), and the solution
was chromatographed on silica. Elution with CH2Cl2/hexane
(1/1, v/v) gave a purple band consisting of a small amount of
purple 1. Further elution with THF gave a red-orange band
containing compound 4. Addition of hexane and slow evapora-
tion gave 4 as orange crystals. Yield: 0.174 g, 73%. Anal. Calcd
for C20H23N2NiO2PS2: C, 50.34; H, 4.86; N, 5.87. Found: C,
Ack n ow led gm en t. We thank the Spanish MCYT
(Project BQU2002-03414) and J unta de Castilla y Leo´n
(VA052/03) for financial suppot and the MEC (Program
F.P.U.) for a grant to E.B.
Su p p or tin g In for m a tion Ava ila ble: Complete tables of
atomic coordinates, anisotropic thermal parameters, and bond
lengths and angles for the structures of 2-5; these data are
also available as CIF files. This material is available free of
charge via the Internet at http://pubs.acs.org.
50.16; H, 5.03; N, 5.72. IR (CH2Cl2): ν(CN) 2192, 2175 cm-1
.
1H NMR (CDCl3; δ (ppm)): 7.28 (t(7), 2H, H4 of Xyl), 7.14 (d(7),
4H, H3and H5of Xyl), 4.12 (m, 2H, POCH2), 2.42 (s, 12H, CH3
of Xyl), 1.35 (m, 3H, POCH2CH3). 31P{1H} NMR (δ (ppm)):
54.4.
OM0343364
[Ni{S2P (OEt)2}{2-p yCHdNC6H4-Me-4}2][S2P (OEt)2] (5).
To a solution of 1 (0.214 g, 0.5 mmol)6 in CH2Cl2 (15 mL) was
added 2-pyCHdNC6H4-Me-4 (0.196 g, 1 mmol). The mixture
was stirred at room temperature for 2 h. The color of the
solution changed from purple to red-brown. The solvent was
evaporated to dryness, and the residue was washed with
(15) SAINT+: SAX area detector integration program, Version 6.02;
Bruker AXS, Inc., Madison, WI, 1999.
(16) Sheldrick, G. M. SHELXTL, An Integrated System for Solving,
Refining, and Displaying Crystal Structures from Diffraction Data,
Version 5.1; Bruker AXS, Inc., Madison, WI, 1998.
(17) Sheldrick, G. M. SADABS, Empirical Absorption Correction
Program; University of Go¨ttingen, Go¨ttingen, Germany, 1997.