Reactions of a phosphinoimino-thiazoline-based metalloligand with organic and inorganic electrophiles and metal-induced ligand rearrangements

Article abstract of DOI:10.1021/om100466n

The reaction of the neutral Pt(II) bischelated complex cis-[Pt{Ph ₂PNA·A·A·CA·A·A·NCH ₂CH₂S}₂] ([Pt(2_-H)₂], 1; 2 = Ph₂PNHC=NCH₂CH₂S, N-(diphenylphosphino)- thiazoline-2-amine) with the organic electrophile EtN=C=S yielded complex [Pt(2_-H)(2_-HA·EtNCS)] (3) as a result of the nucleophilic attack of the coordinated 2-((diphenylphosphino)imino)thiazolidin- 3-yl moiety on the heteroallene carbon atom and coordination of the sulfur atom to the metal. The reaction of 1 with [Cu(NCMe)₄]PF₆ also proceeded by nucleophilic attack of the P-N nitrogen atom on Cu(I) and afforded the coordination polymer [1·Cu]_∞[PF₆] _∞ (4). The reaction of ligand 2 with NiBr₂· xH₂O resulted in a molecular rearrangement and afforded an unexpected pentacoordinated diamagnetic complex, [Ni(2){trans-Ph₂PN=C- N(PPh₂)CH₂CH₂S}Br]Br (6), which likely arises from a metal-templated ligand coupling in the presence of water acting as promoter. Complex 6 was evaluated as a precatalyst for ethylene oligomerization, showing good activities with EADC as cocatalyst. All new complexes were structurally characterized by X-ray diffraction.

Full text of DOI:10.1021/om100466n

6660 Organometallics 2010, 29, 6660–6667
DOI: 10.1021/om100466n
Reactions of a Phosphinoimino-thiazoline-Based Metalloligand
with Organic and Inorganic Electrophiles and Metal-Induced
Ligand Rearrangements
Shuanming Zhang, Roberto Pattacini, and Pierre Braunstein*
ꢀ
Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Universite de Strasbourg,
4 Rue Blaise Pascal, F-67081 Strasbourg, France
Received May 14, 2010
The reaction of the neutral Pt(II) bischelated complex cis-[Pt{Ph2PN
C
NCH2CH2S}2]
j
3 3 3 3 3 3
jj
([Pt(2-H)2], 1; 2 = Ph2PNHCdNCH2CH2S, N-(diphenylphosphino)-thiazoline-2-amine) with
the organic electrophile EtNdCdS yielded complex [Pt(2-H)(2-H EtNCS)] (3) as a result of the
3
nucleophilic attack of the coordinated 2-((diphenylphosphino)imino)thiazolidin-3-yl moiety on the
heteroallene carbon atom and coordination of the sulfur atom to the metal. The reaction of 1 with
[Cu(NCMe)4]PF6 also proceeded by nucleophilic attack of the P-N nitrogen atom on Cu(I) and
afforded the coordination polymer [1 Cu]¥[PF6]¥ (4). The reaction of ligand 2 with NiBr2 xH2O
3
3
resulted in a molecular rearrangement and afforded an unexpected pentacoordinated diamagnetic
complex, [Ni(2){trans-Ph2PNdC-N(PPh2)CH2CH2S}Br]Br (6), which likely arises from a metal-
templated ligand coupling in the presence of water acting as promoter. Complex 6 was evaluated as a
precatalyst for ethylene oligomerization, showing good activities with EADC as cocatalyst. All new
complexes were structurally characterized by X-ray diffraction.
Introduction
ligands readily form a number of transition metal complexes.3
Subtle but sometimes significant differences have been ob-
served between oxazoline- and thiazoline-based systems.2
Chelating P,N ligands and their metal complexes continue to
attract much interest owing to their intrinsic properties and
numerous applications.1 We recently found that unusual mo-
lecular rearrangements involving P-C and P-N bond forma-
tion/breaking can occur during the synthesis of the phosphine
ligands (2-oxazoline-2-ylmethyl)diphenylphosphine (Lox) and
(2-thiazoline-2-ylmethyl)diphenylphosphine (Lth).2 These
*To whom correspondence should be addressed. E-mail: braunstein@
unistra.fr. Phone: þ33 3 68 85 13 08. Fax: þ33 3 68 85 13 22.
(1) For example, see: (a) Maggini, S. Coord. Chem. Rev. 2009, 253,
1793–1832. (b) Mata, Y.; Pamies, O.; Dieguez, M. Adv. Synth. Catal. 2009,
351, 3217–3234. (c) Willms, H.; Frank, W.; Ganter, C. Organometallics 2009,
28, 3049–3058. (d) Benito-Garagorri, D.; Kirchner, K. Acc. Chem. Res. 2008,
41, 201–213. (e) Roseblade, S. J.; Pfaltz, A. Acc. Chem. Res. 2007, 40, 1402–
11. (f) Braunstein, P. Chem. Rev. 2006, 106, 134–159. (g) Braunstein, P.
J. Organomet. Chem. 2004, 689, 3953–3967. (h) Guiry, P. J.; Saunders, C. P.
Adv. Synth. Catal. 2004, 346, 497–537. (i) Chelucci, G.; Orru, G.; Pinna,
G. A. Tetrahedron 2003, 59, 9471–9515. (j) Pfaltz, A.; Blankenstein, J.;
Hilgraf, R.; Hormann, E.; McIntyre, S.; Menges, F.; Schonleber, M.; Smidt,
S. P.; Wustenberg, B.; Zimmermann, N. Adv. Synth. Catal. 2003, 345, 33–44.
(k) Braunstein, P.; Naud, F. Angew. Chem., Int. Ed. 2001, 40, 680–699.
(l) Helmchen, G.; Pfaltz, A. Acc. Chem. Res. 2000, 33, 336–345. (m) Slone,
C. S.; Weinberger, D. A.; Mirkin, C. A. Prog. Inorg. Chem. 1999, 48, 233–350.
(n) Espinet, P.; Soulantica, K. Coord. Chem. Rev. 1999, 193-195, 499–556.
(2) Pattacini, R.; Margraf, G.; Messaoudi, A.; Oberbeckmann-Winter,
N.; Braunstein, P. Inorg. Chem. 2008, 47, 9886–9897.
When the PCH2 group in a chelate structure of type A
(Chart 1) is replaced with an isoelectronic PNH unit, as in B,
deprotonation in R-position to phosphorus is facilitated, and
the resulting metal complexes, of type C and D, respectively,
can be used as metalloligands owing to the resulting electron-
rich character of the carbon or nitrogen centers, respectively,
which are the sites of reaction with electrophiles.4 Similarly,
starting from complexes of the type E and F, which contain
neutral, chelating P,O ligands, metalloligands of type G and
H,5 respectively, have been obtained and their reactivity
(3) (a) Jie, S.; Agostinho, M.; Kermagoret, A.; Cazin, C. S. J.;
Braunstein, P. Dalton Trans. 2007, 4472–4482. (b) Braunstein, P.; Clerc,
G.; Morise, X.; Welter, R.; Mantovani, G. Dalton Trans. 2003, 1601–1605.
(c) Braunstein, P.; Clerc, G.; Morise, X. New J. Chem. 2003, 27, 68–72.
(d) Braunstein, P.; Naud, F.; Rettig, S. J. New J. Chem. 2001, 25, 32–39.
(e) Braunstein, P.; Graiff, C.; Naud, F.; Pfaltz, A.; Tiripicchio, A. Inorg.
Chem. 2000, 39, 4468–4475. (f) Braunstein, P.; Fryzuk, M. D.; Le Dall, M.;
Naud, F.; Rettig, S. J.; Speiser, F. Dalton Trans. 2000, 1067–1074.
(4) (a) Pattacini, R.; Giansante, C.; Ceroni, P.; Maestri, M.; Braunstein, P.
Chem. Eur. J. 2007, 13, 10117–10128. (b) Margraf, G.; Pattacini, R.; Messaoudi,
A.; Braunstein, P. Chem. Commun. 2006, 3098–3100.
(5) (a) Braunstein, P.; Frison, C.; Oberbeckmann-Winter, N.; Morise, X.;
ꢀ
Messaoudi, A.; Benard, M.; Rohmer, M.-M.; Welter, R. Angew. Chem., Int.
Ed. 2004, 43, 6120–6125. (b) Oberbeckmann-Winter, N.; Braunstein, P.; Welter,
R. Organometallics 2005, 24, 3149–3157.
r
pubs.acs.org/Organometallics
Published on Web 11/24/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 24, 2010 6661
Chart 1
in the absence of an exhaustive structural characterization
when attempting to relate the structures of Ni(II) complexes
to their catalytic properties. Indeed, numerous P,N-chelated
Ni(II) complexes are highly active precatalysts in, for exam-
ple, ethylene oligomerization,8 and 6 was evaluated as a
precatalyst for this reaction.
Results and Discussion
Reactions with an Organic Electrophile. We previously
reacted the stable neutral Pt(II) bischelate complex
cis-[Pt{Ph2PN
C
NCH2CH2S}2] ([Pt(2-H)2], 1; 2 =
j
3 3 3 3 3 3
jj
Ph2PNHCSCH2CH2N) (Scheme 1) with Ag(I) and Au(I)
salts to form bimetallic complexes in which the d10 metal
center is coordinated to one or both of the electron-rich
nitrogen atoms of the 2-((diphenylphosphino)imino)-
thiazolidin-3-yl moiety.4 We have now exploited the nucleo-
philicity of the latter atoms toward the organic electrophilic
heteroallene EtNdCdS to examine the regioselectivity of the
reaction and functionalize further the metalloligand. Reac-
tion of EtNdCdS with 1 afforded the complex [Pt(2-H)-
(2-H EtNCS)] (3, Scheme 2), and its structure was deter-
3
mined by single-crystal X-ray diffraction (Figure 1). The
isothiocyanate molecule has reacted selectively on one of
the noncoordinated nitrogen atoms through its electrophilic
sp-hybridized carbon. The resulting ligand chelates the metal
through the phosphorus and the newly formed thioureate
function, while the originally chelating thiazoline moiety has
been decoordinated. A control of the temperature is essential
since below 80 ꢀC the reaction is extremely slow, whereas
above 85 ꢀC side products are observed. Clean incorporation
of a second EtNdCdS molecule was not observed.
investigated.1f,6 The enhanced acidity of the NH group in
Ph2PNHPPh2 compared to that of the CH2 group in
Ph2PCH2PPh2 has also been recognized.7 Neutral Pt(II)
bischelated complexes containing moieties of type D were
recently synthesized from a series of functional phosphines
based on amino-thiazole and -thiazoline moieties in the
presence of NEt3 as a base (see Scheme 1 for phosphino-
amino thiazoline derivatives).4
In the molecular structure of 3 in 3 CH2Cl2, the metal
3
center remains chelated by one of the deprotonated ligands
2-H of precursor 1, through the P2 and N5 atoms. The
slightly distorted square-planar coordination is completed
by a monoanionic P,S chelating ligand resulting from the
addition of EtNdCdS to 2-H and formation of the C4-N1
bond. The P1 and P2 phosphine donor atoms are in mutually
cis position. The geometrical parameters of the ligand 2-H
remain analogous to those found in the parent complex 1,4a
with a notably short P2-N4 bond and a delocalization of the
thiazoline C-N double bond over the N5-C20-N4 group.
Complex cis-[Pt{Ph2PN
C
NCH2CH2S}2] (1) reacts
j
3 3 3 3 3 3
jj
faster with metal centers such as Ag(I)4b and Au(I)4a and
yields more stable products than its analogues in which the
thiazoline moiety is replaced with the heteroaromatic groups
benzothiazole, thiadiazole, or thiazole. In contrast to the
latter complexes, complex 1 shows fluorescence emission in
the solid state at room temperature, which can be tuned by
exposing the complex to alcohols.4a Such molecules interact
in the solid state with the exocyclic, deprotonated, and
electron-rich nitrogen atoms via H-bonds. These N donors
are therefore central to the chemical and physical properties
of complexes of type 1, whereas the sulfur atoms have
remained, so far, spectators. Herein, we explore the reactivity
of 1 toward further electrophilic reagents, such as the organic
heteroallene EtNdCdS and Cu(I) complexes, to examine
the level of selectivity of these reactions. We shall see that in
both cases the P-N nitrogen is again selectively involved in
the reactions, while no insertion into the Pt(II)-N bond is
observed. We have also observed a water-promoted rearran-
gement of the diphenylphosphino-2-amino-2-thiazoline ligand,
which results in an unexpected Ni(II) bromide complex. Its
formation further highlights that caution should be exerted
The N1-C1 bond in the 2-H EtNCS moiety is significantly
3
longer than the N4-C20 bond, while the thiazoline NdC
double bond is now localized between N2 and C1. The N1,
C4,S1,N3 group of atoms can be seen as forming a depro-
tonated thiourea, with a thiolate character for the C-S
group.
Reactions of organic isocyanates and isothiocyanates with
the sp2 carbon in R-position to the coordinated phosphorus
(8) For example, see: (a) Chavez, P.; Guerrero Rios, I.; Kermagoret,
A.; Pattacini, R.; Meli, A.; Bianchini, C.; Giambastiani, G.; Braunstein,
P. Organometallics 2009, 28, 1776–1784. (b) Anderson, C. E.; Batsanov,
A. S.; Dyer, P. W.; Fawcett, J.; Howard, J. A. K. Dalton Trans. 2006, 5362–
5378. (c) Speiser, F.; Braunstein, P.; Saussine, L. Acc. Chem. Res. 2005, 38,
784–793. (d) Weng, Z.; Teo, S.; Koh, L. L.; Hor, T. S. A. Angew. Chem., Int.
Ed. 2005, 44, 7560–7564. (e) Speiser, F.; Braunstein, P.; Saussine, L.; Welter,
R. Inorg. Chem. 2004, 43, 1649–1658. (f) Speiser, F.; Braunstein, P.;
Saussine, L. Organometallics 2004, 23, 2625–2632. (g) Chen, H.-P.; Liu,
Y.-H.; Peng, S.-M.; Liu, S.-T. Organometallics 2003, 22, 4893–4899.
(h) Braunstein, P.; Pietsch, J.; Chauvin, Y.; DeCian, A.; Fischer, J.
J. Organomet. Chem. 1997, 529, 387–393.
(6) Apfelbacher, A.; Braunstein, P.; Brissieux, L.; Welter, R. Dalton
Trans. 2003, 1669.
(7) (a) Bhattacharyya, P.; Woollins, D. Polyhedron 1995, 14, 3367–
3388. (b) Laguna, A.; Laguna, M. J. Organomet. Chem. 1990, 394,
743.

6662 Organometallics, Vol. 29, No. 24, 2010
Scheme 1. Reaction of the Neutral Pt(II) Metalloligand 1 with Electrophilic d10 Metal Reagents4
Zhang et al.
Scheme 2
atom of phosphinoenolate ligands have been reported.9 A
Pt(II) complex bearing a P,S chelating Ph2PN(R)C(dNR)S
ligand, sharing similarities with 2-H EtNCS, resulted from
3
the reaction of RNHC(dS)NHR thioureas with [Pt(dppm-H)2]
(dppm = bis(diphenylphosphino)methane).10 We did not
observe any reaction between 1 and CO2, another hetero-
cumulene, which is known, however, to be less reactive.11
Figure 1. ORTEP of the molecular structure of 3 in 3 CH2Cl2.
Hydrogen atoms and solvent molecules are omitted for clarity.
Ellipsoids include 50% of the electron density. Selected dis-
3
€
(9) (a) Henig, G.; Schulz, M.; Windmuller, B.; Werner, H. Dalton
Trans. 2003, 441–448. (b) Werner, H.; Bank, J.; Windm€uller, B.; Gevert, O.;
Wolfsberger, W. Helv. Chim. Acta 2001, 84, 3162–3177. (c) Braunstein, P.;
Nobel, D. Chem. Rev. 1989, 89, 1927–1945. (d) Bouaoud, S.-E.; Braunstein,
P.; Grandjean, D.; Matt, D.; Nobel, D. Inorg. Chem. 1988, 27, 2279–2286.
(e) Bouaoud, S.-E.; Braunstein, P.; Grandjean, D.; Matt, D.; Nobel, D. Chem.
Commun. 1987, 488–490.
(10) Okeya, S.; Shimomura, H.; Kushi, Y. Chem. Lett. 1992, 2019–
2022.
(11) Braunstein, P.; Matt, D.; Nobel, D. Chem. Rev. 1988, 88,
747–764.
˚
tances (A) and angles (deg): Pt1-P1 2.2256(12), Pt1-P2
2.2754(13), Pt1-N5 2.069(4), Pt1-S1 2.3045(13), P1-N1
1.724(4), P2-N4 1.666(5), N1-C4 1.407(6), N1-C1 1.419(6),
N2-C1 1.264(7), C1-S3 1.781(6), C4-S1 1.770(5), N3-C4
1.27(2), N4-C20 1.319(7), N5-C20 1.333(7), C20-S2
1.771(5); P1-Pt1-P2 101.82(5), N5-Pt1-P2 79.66(13),
N5-Pt1-S1 90.91(12), P1-Pt1-S1 87.67(5).

Article
Organometallics, Vol. 29, No. 24, 2010 6663
Scheme 3
Figure 2. Solid-state 31P{1H} MAS NMR spectrum of 4. Low-
intensity peaks at ca. 150, -20, and -60 ppm are rotation bands.
Figure 4. Orthogonal views of the crystal structure of the
Pt(II)-Cu(I) coordination polymer 4 CH2Cl2 CH3CN, display-
3
3
ing a fraction of the infinite [1 Cu]¥ cationic chain. Views are
approximately along axis c (up) and b (down). Color code: blue:
nitrogen, yellow: sulfur, gray: carbon, violet: phosphorus.
3
Scheme 45b
at-144 ppm. This spectrum is fully consistent with the results
of an X-ray diffraction study performed on single crystals of
4 CH2Cl2 MeCN obtained by slow diffusion of an aceto-
3
3
nitrile solution of [Cu(NCMe)4]PF6 into a dichloromethane
solution of 1 (Figures 3 and 4).
In the structure of 4, the Pt(II) bischelated complex 1 is
bonded to Cu(I) cations through the nitrogen atoms in
R-position to the phosphorus donors. Units of 1 are thus
connected by bare Cu(I) cations to form an infinite cationic
Figure 3. ORTEP of the structure of the cationic, asymmetric
unit in 4 CH2Cl2 CH3CN. Hydrogen atoms and solvent mole-
cules are omitted for clarity. Ellipsoids include 50% of the
3
3
chain of formula [1 Cu]¥. The copper atoms show a slightly
˚
3
electron density. Selected distances (A) and angles (deg):
distorted linear coordination geometry, with a Cu-N bonding
distance of 1.881(10) A, similar to those reported for such a
Pt1-P2 2.241(3), Pt1-P1 2.250(3), Pt1-N2 2.102(10), Pt1-N4
2.105(10), Cu1-N1 1.881(10), P1-N1 1.684(11), P2-N3
1.683(10), N1-C1 1.332(17), N2-C1 1.319(15), N3-C16 1.325(17),
N4-C16 1.329(15); P2-Pt1-P1 100.24(11), N4-Pt1-P2
80.6(3), N2-Pt1-P1 80.4(3), N2-Pt1-N4 98.8(4),
N1-Cu1-N3 179.4(5).
˚
bond in the literature [mean values from CCDC for Cu-N
˚
bonds: 1.882 A (based on 427 Cu-N distances in two-
˚
coordinated Cu complexes) or 1.880 A (based on 97 struc-
tures displaying two sp2 N atoms and a two-coordinated Cu
center)]. This is reminiscent of the situation found in a
heterotrinuclear complex in which a Cu(I) cation bridges
Reactions with an Inorganic Electrophile. Complex 1 re-
acted with [Cu(NCMe)4]PF6 on the same P-bound nitrogen
as the isothiocyanate. This selective reaction resulted rapidly
in the precipitation of the remarkably stable bimetallic
two neutral [Pd(dmba){Ph2PN C(
O)Me}] complexes
3 3 3 3 3 3
via their P-bound nitrogen atom (Scheme 4).5b The geo-
metrical parameters within 4 are similar to those displayed
by the parent complex.
polymer [1 Cu]¥[PF6]¥ (4, Scheme 3), whose insolubility in
3
organic solvents, including DMSO, facilitates its purifica-
tion. In the solid state, its 31P{1H} MAS NMR spectrum
(Figure 2) shows a singlet at 70 ppm, with 195Pt satellites
[1J(31P,195Pt) = 3220 Hz] and the typical PF6 septuplet
The crystal packing in 4 CH2Cl2 MeCN (Figure 5) de-
serves some comments. Cationic [1 Cu]¥ chains are adjacent
and form cationic layers, which alternate with anionic layers
3
3
3

6664 Organometallics, Vol. 29, No. 24, 2010
Zhang et al.
Figure 6. ORTEP of the molecular structure of the cationic
complex in 6 CH2Cl2. Hydrogen atoms and solvent molecules
3
are omitted for clarity. Ellipsoids include 50% of the electron
˚
density. Selected distances (A) and angles (deg): Ni1-N2
1.942(5), Ni1-P2 2.1742(16), Ni1-P3 2.1898(17), Ni1-P1
2.2880(16), Ni1-Br1 2.4577(9), P1-N1 1.703(5), P2-N3
1.659(5), P3-N4 1.717(5), N1-C1 1.334(8), N2-C1 1.290(8),
N2-C2 1.470(8), N3-C16 1.295(8), N4-C16 1.360(8);
P3-Ni1-P1 120.30(6), P1-Ni1-Br1 111.91(5), P3-Ni1-Br1
127.34(5), P2-Ni1-P1 98.27(6), N2-Ni1-P2 178.23(16),
P2-Ni1-P3 89.23(6), P2-Ni1-Br1 89.88(5), N2-Ni1-P3
90.47(15), N2-Ni1-P1 83.39(15), N2-Ni1-Br1 88.91(15).
Scheme 6
Figure 5. Structural diagram of the crystal packing in 4 CH2Cl2
3
3
CH3CN: quadruple cell content (up, phenyls omitted) and
orthogonal view of one of the anionic PF6 CH2Cl2 MeCN
layers.
3
3
In the molecular structure of 6 in 6 CH2Cl2, the metal
3
Scheme 5
center in the cationic complex shows a slightly distorted
trigonal-bipyramidal coordination geometry, the nickel
atom being chelated by ligand 2 (through P1 and N2), a
terminal bromide, and P,P-chelating diphosphine 5. The N2
atom from 1 and P2 from 5 are in mutually trans positions,
occupying the apexes of the bipyramid. A bromide ligand is
in the equatorial plane, while a second bromide acts as a
counterion, far from the metal center. Despite a disorder in
the N4, C17, C18, S2, C16 ring, which affects the environ-
ment of N4 and prevents a detailed discussion of the bond
angles, this nitrogen atom shows an almost planar geometry.
This is suggestive of interactions of its lone pair with C16 and
is consistent with a C16-N4 bond distance intermediate
between a single and a double bond. Ligand 5 is the (E)
isomer, with respect to the N3dC16 double bond, of the
diphosphine prepared earlier by reaction of Ph2PCl with
2-amino-2-thiazoline.4b In this reaction, the (E) isomer was
not observed.4b Furthermore, monophosphine 2 was shown
to be in equilibrium with (Z)-5 and 2-amino-2-thiazoline
(Scheme 6).4b
of formula PF6 CH2Cl2 MeCN. The photophysical proper-
ties of this bimetallic coordination polymer will be examined
in the near future.
3
3
The reactivity of the exocyclic nitrogen atom in chelated
phosphino-aminothiazolines was further confirmed when
2 was reacted with NiBr2 xH2O, in an attempt to prepare
3
a bischelated Ni(II) complex. Whatever the L/Ni ratio
between 1 and 3, the reaction readily gave rise to the formation
of the Ni(II) complex [Ni(2)(5)Br]Br (6, Scheme 5, Figure 6), in
which 5 is the neutral diphosphine (E)-N-(3-diphenylphosphi-
no)thiazolidin-2-ylidene)-diphenylphosphinamine E-Ph2PNd
However, several observations indicate that this equilib-
rium is unlikely to be the source of (E)-5 in 6: (a) this would
imply a (Z) f (E) isomerization of the phosphine, which has
been observed neither for the free ligand nor in the reactions
C-N(PPh2)CH2CH2S.

Article
Organometallics, Vol. 29, No. 24, 2010 6665
Scheme 7
of (Z)-5 with Pd(II) salts; (b) the equilibrium between
monophosphine 2 and (Z)-5 and 2-amino-2-thiazoline is dra-
matically shifted to the left in THF (the solvent used for the
formation of 6; and (c) the reaction of 2 with anhydrous NiBr2
did not give 6, suggesting a role for water in the ligand re-
arrangement, but the products could not be characterized due
to their poor solubility in organic solvents. Since hydrolysis
products were not observed when NiBr2 xH2O was used
3
in place of NiBr2, water would act as a promoter for the
reaction and not as a stoichiometric reagent. To summarize,
it is likely that (E)-5 is formed by a metal-templated coupling
of two molecules of 2, with concomitant formation of 2-
amino-2-thiazoline. A tentative reaction pathway is pro-
posed in Scheme 7, featuring hydrolytic P-N bond cleavage
and coupling between coordinated diphenyl-phosphinous
acid and 2. Pt(II) salts of the type a have been indeed
observed in the case of diphenylphosphino-2-amino-2-
thiazoles.12
Figure 7. 31P{1H} NMR spectrum of 6 in CDCl3. Tentative
assignment. See Figure 6 for the atom labeling.
A pentacoordinated Ni(II) center with P3,N,Br donors has
been observed in a complex resulting from partial hydro-
lysis of a bis-aminophosphine, one of the three P-N bonds
underwent hydrolysis, and the resulting phosphinate was
coordinated to the Ni center.13
second-order effects and coupling constants of 290 Hz (P1,P3),
109 Hz (P2,P3), and 49 Hz (P1,P2), respectively.14
Catalytic Oligomerization of Ethylene. Complex 6 has been
tested as a precatalyst in the oligomerization of ethylene with
variable amounts of AlEtCl2 and MAO as cocatalysts (Table 1).
Under conditions similar to those previously used with other
Ni(II) complexes with P,N ligands,8a,c,e,f,15 we observed only
Complex 6 is diamagnetic, and its 31P{1H} NMR data
are fully consistent with its X-ray structure. The spectrum
(Figure 7) corresponds to the expected ABC spin system and
consists of three doublets of doublets at δ 44.6, 53.8, and
61.3 ppm tentatively assigned to P1-P3, respectively, showing
a moderate activity of ca. 5200 mol C2H4/(mol Ni h) with
3
MAO (300 equiv), with formation of mostly butenes and
hexenes (of which 43% R-butene and 12.3% R-hexene,
respectively); traces of octenes and decenes were also observed.
(12) Milton, H. L.; Wheatley, M. V.; Slawin, A. M. Z.; Woollins, J. D.
Inorg. Chim. Acta 2005, 358, 1393–1400.
(13) Benito-Garagorri, D.; Mereiter, K.; Kirchner, K. Eur. J. Inorg.
(15) Kermagoret, A.; Braunstein, P. Organometallics 2008, 27, 88–99.
Speiser, F.; Braunstein, P.; Saussine, L.; Welter, R. Organometallics 2004,
23, 2613–2624. Speiser, F.; Braunstein, P.; Saussine, L. Dalton Trans. 2004,
1539–1545. Speiser, F.; Braunstein, P.; Saussine, L. Organometallics 2004,
23, 2633–2640.
Chem. 2006, 4374–4379.
(14) For an example of P-Ni-P angle-dependent P,P coupling on
Ni(II) see for example: Goesmann, H.; Matern, E.; Olkowska-Oetzel, J.;
Pikiez, J.; Fritz, G. Z. Anorg. Allg. Chem. 2001, 627, 1181–1184.

6666 Organometallics, Vol. 29, No. 24, 2010
Table 1. Catalytic Data for Complex 6 in Ethylene Oligomerization with EADC and MAO as Cocatalysta
Zhang et al.
selectivity (mass %)
C6
MAO
(equiv)
EADC
(equiv)
productivity
[g C2H4/(g Ni h)]
TOF [mol C2H4/
(mol Ni h)]
1-butene
(mol %)
C4
C8
3
3
3
6
10
91
85
73
77
8
13
24
14
1
1
2
7
1386
15 150
18 400
2485
2900
31 700
38 500
5200
17
14
6
300
43
a Conditions: T = 30 ꢀC, 10 bar of C2H4, 35 min, 4 ꢁ 10-5 mol of complex; solvent: 13.5, 12, and 10 mL of chlorobenzene for 3, 6, 10 equiv of EADC,
respectively (1.5, 3, and 5 mL of EADC solution in toluene); 12 mL of chlorobenzene for MAO (8 mL of cocatalyst solution).
However, with as little as 6 or 10 equiv of AlEtCl2 (EADC),
a significant conversion [TOF: 31700 and 38 500 mol C2H4/
(mol Ni h) respectively] was observed and mostly dimers
were formed (85% and 73%, respectively). A significant
isomerization process occurred, since only a small percent-
age of 1-butene was observed. The remaining products were
hexenes, whereas only traces of higher olefins were detected.
With 3 equiv of EADC, the activity dropped significantly
10 h and then cooled to room temperature. The volatiles were
removed under reduced pressure, and the residue obtained was
washed with pentane (3 ꢁ 10 mL). Evaporation of the volatiles
gave compound 3 as a colorless powder. Yield: 0.080 g, 72%.
The product was recrystallized by layering a CH2Cl2 solution
3
1
3
of 3 with pentane. H NMR (CDCl3): δ 1.32 (t, 3H, JH-H
=
7.3 Hz, CH3, EtNCS), 2.68 (t, 2H, JH-H = 7.8 Hz, SCH2,
3
3
P,S), 3.40 (t, 2H, JH-H = 7.8 Hz, NCH2, P,S), 3.52 (t, 2H,
3
3JH-H = 7.3 Hz, SCH2, P,N), 3.59 (q, 2H, JH-H = 7.3 Hz,
CH2, EtNCS), 4.14 (t, 2H, 3 JH-H = 7.3 Hz, NCH2, P,N), 6.99-
7.52 (m, 20H, Ph). 31P{1H} NMR (CDCl3): δ 67.6 (d, 2J(P,P) =
7.5 Hz, 1J(31P-195Pt) = 3274 Hz, P,S), 78.9 (d, 2J(P,P) =
7.5 Hz, 1J(31P-195Pt) = 2893 Hz, P,N). 13C{1H} NMR
(CDCl3): δ 15.4 (s, CH3, EtNCS), 33.4 (s, SCH2, P,S), 35.8
(d with 195Pt satellites, 4J(C,P) = 5.3 Hz, 3J(13C,195Pt) = 39 Hz,
SCH2, P,N), 48.2 (s, CH2, EtNCS), 55.7 (d, with 195Pt satellites,
3þ4J (C,P) = 4.1 Hz, 2J(13C,195Pt) = 40 Hz, NCH2, P,N), 57.1
(s, NCH2, P,S), 127.5-133.3 (m, Ph), 156.9 (d, 2J(C,P) =
24.5 Hz, PtSC), 159.6 (d, 2J(C,P) = 4.1 Hz, NdC-S, P,S),
189.0 (s, NdC-S, P,N). Anal. Calcd for C33N5H33P2S3NPt
(852.57): C 46.47, H 3.90, N 8.21. Found: C 46.16, H 4.05, N
7.99.
Preparation and Spectroscopic Data for 4. A solution of
[Cu(NCMe)4]PF6 (0.050 g, 0.134 mmol) in MeCN (4 mL) was
added to a stirred solution of complex 1 (0.103 g, 0.134 mmol) in
CH2Cl2 (10 mL). A colorless precipitate formed immediately.
The solution was stirred for 1 h, and the solid was collected by
filtration and washed with MeCN (10 mL) and CH2Cl2 (10 mL),
yielding 4 as a colorless microcrystalline powder. Yield: 0.122 g,
94%. Single crystals suitable for X-ray diffraction were obtained
within 1 day at room temperature, upon slow diffusion of a MeCN
(1 mL) solution of [Cu(NCMe)4]PF6 (0.005 g, 0.014 mmol) into
a CH2Cl2 (1 mL) solution of complex 1 (0.010 g, 0.013 mmol).
31P{1H} MAS NMR (solid): δ -144 (sept, 1J(P,F) = 714 Hz, PF6),
70 (s, with 195Pt satellites, 1J(P,195Pt) = 3239 Hz, polymer). Anal.
Calcd for C30H28CuF6N4P3PtS2 (974.2): C 36.98, H 2.90, N 5.75.
Found: C 36.81, H 3.06, N 5.69.
[TOF: 2900 [mol C2H4/(mol Ni h)].
3
Conclusion
The multidentate thiazoline-based aminophosphine ligand 2
has a rich coordination chemistry. When deprotonated, their
bischelated platinum(II) complexes show a remarkable
stability. However, this does not preclude further reactions
of these metalloligands with organic or inorganic electro-
philes. The deprotonated exocyclic nitrogen atoms can be
selectively involved in the formation of bimetallic coordina-
tion polymers, which may display interesting photophysical
properties.4b The sulfur atoms do not participate in direct
bonding with the electrophiles examined and remain specta-
tors, although, electronically, they may have an important
role in improving the donor properties of the exocyclic
nitrogens. Complex 6 was tested in the catalytic oligomeriza-
tion of ethylene and showed good activities when EADC was
used as cocatalyst, producing mostly butenes, albeit with
a low selectivity for R-olefins, whereas the use of MAO as
cocatalyst resulted in low conversion.
Experimental Section
General Considerations. All manipulations were carried out
under an inert argon atmosphere, using standard Schlenk-line
conditions and dried and freshly distilled solvents. Unless
Preparation and Spectroscopic Data for 6. To a solution of
N-(diphenylphosphino)-2-amino-2-thiazoline 2(0.786 g, 2.74 mmol)
in CH2Cl2 (100 mL) was added NiBr2 xH2O (prepared from
1
otherwise stated, the H, 13C{1H}, and 31P{1H} NMR spectra
were recorded on a Bruker Avance 300 instrument at 300.13,
75.47, and 121.49 MHz, respectively, using TMS or H3PO4
(85% in D2O) as external standards, with downfield shifts
reported as positive. All NMR spectra were measured at
298 K, unless otherwise specified. The assignment of the signals
3
0.200 g, 0.91 mmol, NiBr2) was added. The resulting solution
was stirred under N2 for 3 h. The volatiles were removed under
reduced pressure, and the violet residue obtained was washed with
THF (10 mL). Evaporation of the volatiles gave compound 6 as a
violet powder, yield (based on NiBr2): 0.571 g, 64%. The product
was recrystallized by layering a CH2Cl2 solution of 6 with diethyl
ether. 1HNMR(CDCl3):δmultiplets at 1.77 (m, 1H), 2.70 (m, 3H),
3.23 (m, 1H), 3.50 (m, 1H), 3.94 (m, 1H), 4.17 (m, 1H), 6.70-8.20
(m, 30H, Ph), 10.5 (br, 1H, NH). 31P{1H} NMR (CDCl3) (tentative
assignment, see Figure 6 for labeling): δ 44.6 (dd, 2J(P2,P3) = 109
1
1
was made by H,1H-COSY, H,13C-HMQC, and 13C-HSQC
experiments. Elemental C, H, and N analyses were performed
ꢀ
by the Service de Microanalyses, Universite de Strasbourg
(France). Complex 1 and ligand 2 (N-(diphenylphosphino)-
thiazoline-2-amine) were prepared according to literature
procedures.4 Ph2PCl and NEt3 were freshly distilled before
use. Anhydrous NiBr2 was prepared by treatment of the hy-
2
Hz, J(P1,P3) = 290 Hz, P3), 53.8 (dd, 2J(P2,P3) = 109 Hz, 2J(P1,
P2)=49 Hz, P2), 61.3 (dd, 2J(P1,P3) = 290 Hz, 2J(P1,P2) = 49 Hz,
P1). ESI-MS (positive ions): m/z 894.9 [M - Br]þ, [M - Br -
HBr]þ =814.0. Anal. Calcd for C42N4H39Br2P3S2Ni (975.34): C
51.72, H 4.03, N 5.74. Found: C 51.43, H 3.99, N 5.71.
drated salt with thionyl chloride. Hydrated NiBr2 (NiBr2
3
xH2O) was prepared by dissolving a known quantity of anhydrous
NiBr2 in water followed by drying under vacuum. Other chemicals
were commercially available and were used as received.
Preparation and Spectroscopic Data for 3. Solid complex 1
(0.100 g, 0.13 mmol) was dissolved in a minimum amount of
liquid EtNCS. The resulting solution was stirred at 83 ꢀC for
Catalytic Oligomerization of Ethylene. The catalytic reactions
were performed in a magnetically stirred (900 rpm) 145 mL
stainless steel autoclave. A 125 mL glass container was used to

Article
Organometallics, Vol. 29, No. 24, 2010 6667
Table 2. X-ray Data Collection and Refinement Parameters
3 CH2Cl2
4 CH2Cl2 CH3CN
6 CH2Cl2
3
3
3
3
formula
C33H33N5P2PtS3,CH2Cl2
C30H28CuN4P2PtS2 PF6,
C42H39Br2N4NiP3S2,CH2Cl2
3
CH3CN,CH2Cl2
1100.20
monoclinic
P21/c
12.1087(3),
26.9287(8),
14.9896(4)
90.00,
127.683(2),
90.00
3868.1(2)
4
1.889
Mr
cell setting
space group
937.78
1060.26
monoclinic
P21/c
14.1050(5),
20.0528(4),
20.2434(5)
90.00,
128.553(2),
90.00
4477.7(2)
4
1.573
orthorhombic
P212121
9.2952(2),
15.7977(2),
24.6944(4)
90.00,
90.00,
90.00
3626.19(11)
4
1.718
˚
a, b, c (A)
R, β, γ (deg)
3
V (A )
˚
Z
Dx (Mg m-3
)
μ (mm-1
)
4.31
0.15 ꢁ 0.15 ꢁ 0.12
4.59
0.15 ꢁ 0.07 ꢁ 0.07
2.57
0.24 ꢁ 0.15 ꢁ 0.15
cryst size (mm)
measd reflns
indep reflns
obsvd reflns
Rint
24 323
10 494
21 049
7568
25 849
8809
9513
0.047
6036
0.062
6637
0.061
θ
max (deg)
R[F2 > 2σ(F2)]
30.1
0.036
0.089
1.02
463
-0.001(5)
26.0
0.070
0.191
1.14
482
26.0
0.060
0.176
1.11
532
wR(F2)
S
no. of params
Flack param
avoid corrosion of the autoclave walls. The preparation of the
precatalyst solution was prepared by dissolving 39.2 mg of dried
crystals of 6 (4 ꢁ 10-5 mol) in chlorobenzene. When AlEtCl2
was used as a cocatalyst, 4 ꢁ 10-5 mmol of 6 was dissolved in
13.5, 12, or 10 mL of cholorobenzene depending on the amount
of the cocatalyst and injected into the reactor under an ethylene
flux. Then 1.5, 3, or 5 mL of a cocatalyst toluene solution, (3, 6,
or 10 equiv, respectively) was added (total volume: 15 mL). With
MAO as a cocatalyst, 4 ꢁ 10-5 mol of 6 was dissolved in 12 mL
in chlorobenzene and injected into the reactor under an ethylene
flux. Then 8 mL of a cocatalyst solution and 300 equiv of MAO
were added. All catalytic reactions were started between 25 and
30 ꢀC. No cooling of the reactor was done during the reaction.
After injection of the catalyst and cocatalyst solutions under
a constant low flow of ethylene, the reactor was pressurized to
10 bar. The temperature increased, due solely to the exothermi-
city of the reaction. The 10 bar working pressure was maintained
through a continuous feed of ethylene from a bottle placed on a
balance to allow continuous monitoring of the ethylene uptake.
At the end of each test (35 min) a dry ice bath was used to rapidly
cool the reactor. When the inner temperature reached 0 ꢀC, the
ice bath was removed, allowing the temperature to slowly rise to
10 ꢀC. The gaseous phase was then transferred into a 10 L
polyethylene tank filled with water. An aliquot of this gaseous
phase was transferred into a Schlenk flask, previously evacu-
ated, for GC analysis. The amount of ethylene not consumed
was thus determined. Although this method is of limited accu-
racy, it was used throughout and gave satisfactory reproduci-
bility. The products in the reactor were hydrolyzed in situ by the
addition of ethanol (1 mL), transferred into a Schlenk flask, and
separated from the metal complexes by trap-to-trap evaporation
(20 ꢀC, 0.8 mbar) into a second Schlenk flask previously
immersed in liquid nitrogen in order to avoid loss of product.
X-ray Data Collection, Structure Solution, and Refinement for
All Compounds. Suitable crystals for the X-ray analysis of all
compounds were obtained as described above. The intensity
data were collected at 173(2) K on a Kappa CCD diffractom-
eter16 (graphite-monochromated Mo KR radiation, λ = 0.71073 A).
˚
Crystallographic and experimental details for the structures are
summarized in Table 2. The structures were solved by direct methods
(SHELXS-97) and refined by full-matrix least-squares procedures
(based on F2, SHELXL-97)17 with anisotropic thermal parameters
for all the non-hydrogen atoms. The hydrogen atoms were introduced
into the geometrically calculated positions (SHELXS-97 procedures)
and refined riding on the corresponding parent atoms. For
4 CH2Cl2 CH3CN, the C-Cl bond lengths of the dichloro-
3
3
˚
methane molecule were restrained to 1.750 A. In 3 CH2Cl2, the
3
isothiocyanate NEt group was found disordered in two posi-
tions with equal occupancy factors and refined with restrained
anisotropic parameters. The dichloromethane molecule was
disordered in two positions, with equal occupancy factors,
having a chlorine and the carbon in common. For all com-
pounds, a MULTISCAN absorption correction was applied.18
CCDC 776723 (3 CH2Cl2), CCDC 776724 (4 CH2Cl2 MeCN),
3
3
3
and CCDC 776725 (6 CH2Cl2) contain the supplementary
3
crystallographic data for this paper, which can be obtained free
of charge from the Cambridge Crystallographic Data Center via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgment. The work was supported by the
ꢁ
ꢀ
CNRS, the Ministere de l’Enseignement Superieur et de
la Recherche, and the Agence Nationale de la Recherche
(ANR-06-BLAN 410). We thank Lionel Allouche for
NMR experiments.
Supporting Information Available: CIF files giving crystallo-
graphic data. This material is available free of charge via the
Internet at http://pubs.acs.org.
(17) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.
(18) Spek, L. J. Appl. Crystallogr. 2003, 36, 7. Blessing, B. Acta
Crystallogr. 1995, A51, 33.
(16) Bruker-Nonius. Kappa CCD Reference Manual; Nonius BV: The
Netherlands, 1998.