Coordination chemistry of the 2-pyridyidiphosphine ligands, (py)2P(CH(CH2)3CH)P(py)2 and (py)2P(CH2)2P(py)2 (py = 2-pyridyl), with platinum(II) and ruthenium(II). Ruthenium-catalyzed hydrogenation of imines

Article abstract of DOI:10.1021/ic990002o

The synthesis and characterization of a range of Pt(II) and Ru(II) complexes containing the new 2-pyridyldi-phosphine ligand, d(py)pcp = (py)₂P(CH(CH₂)₃CH)P(py)₂ (made as a racemate) and the previously reported d(py)pe = (py)₂P(CH₂)₂P(py)₂ are given (py = 2-pyridyl). The Pt complexes made were cis-PtX₂(d(py)pcp) (X = Cl (1), I (2)), cis-PtX₂(d(py)pe) (X = Cl (3), I (4)), [Pt(d(Py)pcp)₂][PF6]2 (5), and [Pt(d(py)pe)₂][PF₆]₂ (6); these all contain P,P-bonded diphosphine ligand, as evidenced by ³¹P NMR data and by crystallographic data in the case of 2 and 3. The X-ray structure of d(py)pe is also reported. The complexes RuX₂(P,P,N-d(py)pcp)(PPh₃) have cis-halogens and a P,P,N-bonding mode of the pyridyldiphosphine (which incorporates a four-membered P,N-chelate ring) with either a mer-arrangement (in 7a, X = Cl) or a fac-arrangement of the three P donor atoms (in 7b (X = Cl), 8 (X = Br), 9 (X = I)); cis-RuCl₂(dppb)(P,N-PPh₂(py)) (12) (dppb = Ph₂P(CH₂)₄PPh₂) is included because it has a donor set corresponding to that in 7b. Use of the purely P,P donor Ph₂P(CH(CH₂)₃-CH)PPh₂ (dppcp), made as a racemate, affords trans-RuCl₂(dppcp)₂ (10) and tran?-RuCl₂(dppcp)(dppb) (11). Crystallographic data for 7a, 7b, and 12 are reported together with the NMR data for all the Ru complexes. Preliminary results show that the Ru complexes 7b, 8, and 9 are effective precursors for catalytic H₂-hydrogenation of aldimines.

Full text of DOI:10.1021/ic990002o

3
956
Inorg. Chem. 1999, 38, 3956-3966
Ar ticles
Coordination Chemistry of the 2-Pyridyldiphosphine Ligands, (py)2P(CH(CH2)3CH)P(py)2
and (py)2P(CH2)2P(py)2 (py ) 2-Pyridyl), with Platinum(II) and Ruthenium(II).
†
Ruthenium-Catalyzed Hydrogenation of Imines
‡
‡
§
‡
Nathan D. Jones, Kenneth S. MacFarlane, Martin B. Smith, Richard P. Schutte,
Steven J. Rettig,† and Brian R. James*
,‡
,‡
Department of Chemistry, The University of British Columbia, Vancouver, B.C., V6T 1Z1, Canada, and
Department of Chemistry, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
ReceiVed January 6, 1999
The synthesis and characterization of a range of Pt(II) and Ru(II) complexes containing the new 2-pyridyldi-
phosphine ligand, d(py)pcp ) (py)2P(CH(CH2)3CH)P(py)2 (made as a racemate) and the previously reported
d(py)pe ) (py)2P(CH2)2P(py)2 are given (py ) 2-pyridyl). The Pt complexes made were cis-PtX2(d(py)pcp)
(
X ) Cl (1), I (2)), cis-PtX2(d(py)pe) (X ) Cl (3), I (4)), [Pt(d(py)pcp)2][PF6]2 (5), and [Pt(d(py)pe)2][PF6]2 (6);
3
1
these all contain P,P-bonded diphosphine ligand, as evidenced by P NMR data and by crystallographic data in
the case of 2 and 3. The X-ray structure of d(py)pe is also reported. The complexes RuX2(P,P,N-d(py)pcp)(PPh3)
have cis-halogens and a P,P,N-bonding mode of the pyridyldiphosphine (which incorporates a four-membered
P,N-chelate ring) with either a mer-arrangement (in 7a, X ) Cl) or a fac-arrangement of the three P donor atoms
(
in 7b (X ) Cl), 8 (X ) Br), 9 (X ) I)); cis-RuCl2(dppb)(P,N-PPh2(py)) (12) (dppb ) Ph2P(CH2)4PPh2) is
included because it has a donor set corresponding to that in 7b. Use of the purely P,P donor Ph2P(CH(CH2)3-
CH)PPh2 (dppcp), made as a racemate, affords trans-RuCl2(dppcp)2 (10) and trans-RuCl2(dppcp)(dppb) (11).
Crystallographic data for 7a, 7b, and 12 are reported together with the NMR data for all the Ru complexes.
Preliminary results show that the Ru complexes 7b, 8, and 9 are effective precursors for catalytic H2-hydrogenation
of aldimines.
1
Introduction
catalytic applications, including hydrogenation, hydroform-
ylation,
1
,4a,7
8
and carbonylation have been investigated.
A widely used pyridylphosphine is 2-(diphenylphosphino)-
pyridine, PPh2(py) (type I, Chart 1), which as a ligand can adopt
three different coordination modes: P-monodentate, P,N-
The chemistry of heterodifunctional ligands incorporating
both “soft” (e.g. P) and “hard” (e.g. N or O) donor atoms
1,2
continues to attract interest. The coordination chemistry of
-pyridylphosphines in particular has been extensively studied.
9
2
3a,c
4-6
chelate,
dylphosphines such as PPh(py)2, P(py)3, and XPPh3-n(py)n
X ) O, S, AuCl, Au(C6F5); n ) 2, 3) can take on a variety of
and P,N-bridge.
Di- and trisubstituted 2-pyri-
3
In addition to a large number of mononuclear complexes,
several binuclear species as well as clusters and oligomers,
the last three classes employing the ligand in a P,N-bridging
mode, have been characterized. In addition, some homogeneous
4
5
6
(
(
4) (a) Franci o` , G.; Scopelliti, R.; Arena, C. G.; Bruno, G.; Drommi, D.;
Faraone, F. Organometallics 1998, 17, 338. (b) Chan, W.-H.; Zhang,
Z.-Z.; Mak, T. C. W.; Che, C.-M. J. Chem. Soc., Dalton Trans. 1998,
803. (c) Kuang, S.-M.; Xue, F.; Zhang, Z.-Z.; Xue, W.-M.; Che, C.-
M.; Mak, T. C. W. J. Chem. Soc., Dalton Trans. 1997, 3409. (d)
Kuang, S.-M.; Cheng, H.; Sun, L.-J.; Zhang, Z.-Z.; Zhou, Z. Y.; Wu,
B.-M.; Mak, T. C. W. Polyhedron 1996, 15, 3417. (e) Xie, L. Y.;
James, B. R. Inorg. Chim. Acta 1994, 217, 209. (f) De Munno, G.;
Bruno, G.; Arena, C. G.; Drommi, D.; Faraone, F. J. Organomet.
Chem. 1993, 450, 263. (g) Reinhard, G.; Hirle, B.; Schubert, U.; Knorr,
M.; Braunstein, P.; De Cian, A.; Fischer, J. Inorg. Chem. 1993, 32,
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R.-J.; Wang, H.-G.; Wu, Y. J. Organomet. Chem. 1993, 454, 221. (i)
Arena, C. G.; Faraone, F.; Fochi, M.; Lanfranchi, M.; Mealli, C.;
Seeber, R.; Tiripicchio, A. J. Chem. Soc., Dalton Trans. 1992, 1847.
(j) Rotondo, E.; Bruno, G.; Nicol o` , F.; Lo Schiavo, S.; Piraino, P.
Inorg. Chem. 1991, 30, 1195. (k) Maisonnat, A.; Farr, J. P.; Olmstead,
M. M.; Hunt, C. T.; Balch, A. L. Inorg. Chem. 1982, 21, 3961. (l)
Alcock, N. W.; Moore, P.; Lampe, P. A. J. Chem. Soc., Dalton Trans.
1982, 207.
†
Deceased on Oct. 27, 1998. This paper is dedicated to the memory of
Steven Rettig.
‡
The University of British Columbia.
Loughborough University.
§
(
1) For general reviews of P,N ligands, see: (a) Zhang, Z.-Z.; Cheng, H.
Coord. Chem. ReV. 1996, 147, 1. (b) Newkome, G. R. Chem. ReV.
1993, 93, 2067.
(
2) For a general review of P,O ligands, see: Bader, A.; Lindner, E. Coord.
Chem. ReV. 1991, 108, 27.
(
3) (a) Nicholson, T.; Hirsch-Kuchma, M.; Shellenbarger-Jones, A.;
Davison, A.; Jones, A. G. Inorg. Chim. Acta 1998, 267, 319. (b) Baird,
I. R.; Smith, M. B.; James, B. R. Inorg. Chim. Acta 1995, 235, 291.
(c) Braunstein, P.; Kelly, D. G.; Tiripicchio, A.; Ugozzoli, F. Bull.
Soc. Chim. Fr. 1995, 132, 1083. (d) Arena, C. G.; Bruno, G.; De
Munno, G.; Rotondo, E.; Drommi, D.; Faraone, F. Inorg. Chem. 1993,
3
2, 1601. (e) Xie, Y.; Lee, C.-L.; Yang, Y.; Rettig, S. J.; James, B. R.
Can. J. Chem. 1992, 70, 751.
1
0.1021/ic990002o CCC: $18.00 © 1999 American Chemical Society
Published on Web 08/18/1999

Coordination Chemistry of 2-Pyridyldiphosphine Ligands
Inorganic Chemistry, Vol. 38, No. 18, 1999 3957
Chart 1
Chart 2
fragment.15 In the second class, two -PR(py) (R ) Ph, py)
additional coordination modes using a combination of one or
more of the group 15/16 donor centers.10 Recent work within
this laboratory has found an unprecedented P,N,N-coordination
mode for PPh(py)2 and P(py)3.11
In contrast, pyridyldiphosphines have been less studied and,
of those documented, two distinct structural classes are apparent.
In the first class, two -PR2 moieties (R ) Ph, typically) are
directly bonded in the 2- and 6-positions of the pyridine ring,
affording a PNP-ligand system (type II).12 Ligands of this type
readily bridge metal centers and have been used to stabilize
both homo- and heterobimetallic complexes. Introduction of a
fragments are linked by an aliphatic carbon spacer of variable
16
length, linear, branched or cyclic (type IV).
Our interest in pyridylphosphine ligands, especially those of
type IV, stems from the idea that protonation of noncoordinated
pyridine N atoms on the ligand would be a convenient route to
water solubilization of the corresponding metal complexes, with
the ultimate objective being the homogeneous catalytic hydration
3b,e
of olefins in aqueous media. We also believed that catalytic
hydrogenation systems might benefit from the inclusion of
pyridylphosphine ligands in that metal hydride formation via
heterolytic H2 cleavage would be promoted by the presence of
-
CH(R)- (R ) H, Me) spacer between the -PPh2 groups and
17
an intramolecular base.
13
the central pyridyl group (type III) permits extra flexibility
within the PNP-tridentate ligand and, in the case of R ) Me,
allows for the synthesis of C2-symmetric chiral complexes, some
of which have used for the enantioselective hydrogenation of
In this paper we report the synthesis and characterization of
a new pyridyldiphosphine containing a cyclopentane ring bridge,
racemic-(py)2PCH(CH2)3CHP(py)2 (d(py)pcp), isostructural with
1
4
imines. This type of ligand favors bis five-membered chelate
ring formation upon coordination to a mononuclear metal
the tetraphenyl chiral analogue (Ph)2PCH(CH2)3CHP(Ph)2
1
8
(
dppcp) which has been described previously. Both d(py)pcp
3b
and the previously reported (py)2PC2H4P(py)2 (d(py)pe) are
(
5) (a) Gobetto, R.; Arena, C. G.; Drommi, D.; Faraone, F. Inorg. Chim.
Acta 1996, 248, 257. (b) Deeming, A. J.; Smith, M. B. J. Chem. Soc.,
Chem. Commun. 1993, 844 and references therein.
potentially hexadentate P2N4 ligands, and have been observed
1
9
to act as such (Chart 2).
(6) Braunstein, P.; Knorr, M.; Strampfer, M.; De Cian, A.; Fischer, J. J.
Chem. Soc., Dalton Trans. 1994, 117.
Synthetic and characterization details of the coordination
chemistry of d(py)pcp and d(py)pe toward a range of Ru(II)
and Pt(II) fragments are described, as well as preliminary results
for the catalytic hydrogenation of imines using the Ru com-
plexes. The structures of the free ligand d(py)pe, the metal
complexes PtI2(d(py)pcp) (2‚0.18CH2Cl2), PtCl2(d(py)pe) (3‚
CH2Cl2), RuCl2(P,P,N-d(py)pcp)(PPh3) (7a‚2CH2Cl2), RuCl2-
(
7) (a) Drommi, D.; Nicol o` , F.; Arena, C. G.; Bruno, G.; Faraone, F.;
Gobetto, R. Inorg. Chim. Acta 1994, 221, 109. (b) Gladiali, S.; Pinna,
L.; Arena, C. G.; Rotondo, E.; Faraone, F. J. Mol. Catal. 1991, 66,
1
83.
(
8) Zhang, Z.-Z.; Xi, H.-P.; Zhao, W.-J.; Jiang, K.-Y.; Wang, R.-J.; Wang,
H.-G.; Wu, Y. J. Organomet. Chem. 1993, 454, 221.
(9) (a) Xie, Y.; James, B. R. J. Organomet. Chem. 1991, 417, 277. (b)
Newkome, G. R.; Evans, D. W.; Fronczek, F. R. Inorg. Chem. 1987,
(P,P,N-d(py)pcp)(PPh3) (7b‚1.5EtOH), and cis-RuCl2(dppb)-
2
6, 3500. (c) Inoguchi, Y.; Milewski-Mahrla, B.; Neugebauer, D.;
Jones, P. G.; Schmidbaur, H. Chem. Ber. 1983, 116, 1487.(d) Alcock,
N. W.; Moore, P.; Lampe, P. A. J. Chem. Soc., Dalton Trans. 1982,
(15) (a) Hahn, C.; Sieler, J.; Taube, R. Polyhedron 1998, 17, 1183 and
references therein. (b) Hahn, C.; Vitagliano, A.; Giordano, F.; Taube,
R. Organometallics 1998, 17, 2060. (c) Rahmouni, N.; Osborn, J. A.;
De Cian, A.; Fischer, J.; Ezzamarty, A. Organometallics 1998, 17,
2470, and references therein. (d) Jia, G.; Lee, H. M.; Williams, I. D.;
Lau, C. P.; Chen, Y. Organometallics 1997, 16, 3941.
2
2
07. (e) Wajda, A.; Pruchnik, F.; Lis, T. Inorg. Chim. Acta 1980, 40,
07.
(
10) (a) Casares, J. A.; Espinet, P.; Hernando, R.; Iturbe, G.; Villafa n˜ e, F.;
Ellis, D. D.; Orpen, A. G. Inorg. Chem. 1997, 36, 44. (b) Casares, J.
A.; Espinet, P. Inorg. Chem. 1997, 36, 5428 and references therein.
(
2
(
1
c) Schutte, R. P.; Rettig, S. J.; James, B. R. Can. J. Chem. 1996, 74,
064. (d) Guillaume, P.; Postel, M. Inorg. Chim. Acta 1995, 233, 109.
e) Espinet, P.; G o´ mez-Elipe, P.; Villafa n˜ e, F. J. Organomet. Chem.
993, 450, 145. (f) Gregorzik, R.; Wirbser, J.; Vahrenkamp, H. Chem.
(16) (a) Berners-Price, S. J.; Bowen, R. J.; Harvey, P. J.; Healy, P. C.;
Koutsantonis, G. A. J. Chem. Soc., Dalton Trans. 1998, 1743. (b)
Mirabelli, C. K.; Hill, D. T.; Faucette, L. F.; McCabe, F. L.; Girard,
G. R.; Bryan, D. B.; Sutton, B. M.; O’Leary Bartus, J.; Crooke, S. T.;
Johnson, R. K. J. Med. Chem. 1987, 30, 2181. (c) Budzelaar, P. H.
M.; Frijns, J. H. G.; Orpen, A. G. Organometallics 1990, 9, 1222.
(17) James, B. R. In ComprehensiVe Organometallic Chemistry; Wilkinson,
G., Stone, F. G. A., Abel, E. W., Eds; Pergamon: Oxford, 1982;
Chapter 51.
Ber. 1992, 125, 1575. (g) Kurtev, K.; Ribola, D.; Jones, R. A.; Cole-
Hamilton, D. J.; Wilkinson, G. J. Chem. Soc., Dalton Trans. 1980,
5
5.
11) Schutte, R. P.; Rettig, S. J.; Joshi, A. M.; James, B. R. Inorg. Chem.
997, 36, 5809.
(
(
1
12) (a) Kuang, S.-M.; Zhang, Z.-Z.; Wang, Q.-G.; Mak, T. C. W. J. Chem.
Soc., Chem. Commun. 1998, 581. (b) Zhang, J.-K.; Zhang, Z.-M.; Yu,
A.; Zhao, S.-L.; Zhang, W.-D.; Zhang, Z.-Z. Polyhedron 1996, 15,
(18) (a) Indolese, A. F.; Consiglio, G. Organometallics 1994, 13, 2230
and references therein. (b) Morandini, F.; Pilloni, G.; Consiglio, G.;
Sironi, A.; Moret, M. Organometallics 1993, 12, 3495 and references
therein. (c) Cotton, F. A.; Kang, S.-J. Inorg. Chim. Acta 1993, 209,
23. (d) Consiglio, G.; Indolese, A. J. Organomet. Chem. 1991, 417,
C36. (e) Alcock, N. W.; Brown, J. M.; Maddox, P. J. J. Chem. Soc.,
Chem. Commun. 1986, 1532. (f) Allen, D. L.; Gibson, V. C.; Green,
M. L. H.; Skinner, J. F.; Bashkin, J.; Grebenik, P. D. J. Chem. Soc.,
Chem. Commun. 1983, 895.
2
583. (c) McFarlane, H. C. E.; McFarlane, W.; Muir, A. S. Polyhedron
1990, 9, 1757. (d) Wood, F. E.; Hvoslef, J.; Hope, H.; Balch, A. L.
Inorg. Chem. 1984, 23, 4309 and references therein.
(13) (a) Jiang, Q.; Van Plew, D.; Murtuza, S.; Zhang, X. Tetrahedron Lett.
1996, 37, 797. (b) Sablong, R.; Newton, C.; Dierkes, P.; Osborn, J.
A. Tetrahedron Lett. 1996, 37, 4933.
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3958 Inorganic Chemistry, Vol. 38, No. 18, 1999
Jones et al.
Table 1. Solution 31P{ H} NMR Data for Complexes 7-12a
1
P
M
or P
B
2JAM or 2JAB
complex
spin system
AMX
P
A
(ppm)
P
X
2JAX
(Hz)
2JMX or 2JBX
mer-RuCl
2
(d(py)pcp)(PPh
(d(py)pcp)(PPh
(d(py)pcp)(PPh
3
), 7a
38.7 dd
47.8 d
48.8 dd
49.3 dd
48.7 dd
22.8 s
8.0 dd
-
47.5 dd
49.3 dd
44.7 dd
23.3 s
36.5
-7.8 dd
8.8 t
300
27.7
26.5
∼27
24.1
-
24.8
-
21.0
-
fac-RuCl
fac-RuCl
2
3
), 7b
), 7b
A
2
X
b
2
3
ABX
ABX
AMX
A ,B
2 2
AMX
8.9 dd
8.3 dd
1.1 dd
-
31.1
∼31
27.6
-
27.6
∼27
26.5
-
fac-RuBr
fac-RuI (d(py)pcp)(PPh
trans-RuCl (dppcp) , 10
fac-RuCl (dppb) (PPh
(py)), 12d
2
(d(py)pcp)(PPh
3
), 8
c), 9
2
3
2
2
2
2
47.8
-20.9
26.3
34.6
27.4
P
A(A′)
P
B(B′)
J values
(dppb)(dppcp), 11e
AA′BB′
16.5
7.1
2
2
2
2
J
J
J
J
AB 313.8, JA′B′ 312.1
2
trans-RuCl
2
2
AA′ 32.0, JBB′ 34.8
AB′ (or JA′B) -39.6
A′B (or JAB′) -39.1
2
2
a
) for 7a. b In C
Complexes dissolved in CDCl
3
at r.t. unless otherwise indicated; all dd signals are overlapping except for δ(P
(dppb)(PPh (py)) for the cis disposition of the
chloro ligands. A, A′ refer to dppb, and B, B′ to dppcp; data obtained using the program “NMR” Version 1.0 by Calleo Scientific Software; JAB
A
) and δ(P
B 6 6
D .
c
d
Mixture of two diastereomers. Taken from ref 11, in which the complex is described as cis-RuCl
2
2
e
2
2
2
and JA′B′ are due to the trans disposed P atoms, and other J values arise from mutually cis P atoms.
1
(
PPh2(py))‚2.5 CDCl3 (12) (dppb ) Ph2P(CH2)4PPh2) have been
{ H} NMR spectra of the ligand d(py)pcp and its dioxide have been
assigned where possible on the basis of 13C- H HETCOR and APT
experiments. These peaks generally appear as multiplets due to coupling
1
determined by single-crystal X-ray diffraction.
31
to P, and, although the coupling constants have not been determined,
the number of lines observed in each case is given in parentheses
following the peak frequency.
Experimental Section
General Methods and Materials. Unless otherwise stated, manipu-
lations were carried out under Ar using standard Schlenk techniques.
The UV-vis spectra were recorded on a Hewlett-Packard 8452A
Reagent grade solvents (Fisher Scientific) were distilled from CaH
CH Cl ), Na (Et O, C , and hexanes), Mg/I (MeOH and EtOH), or
anhydrous K CO (acetone) under N
The complexes RuCl
2
-1
diode array spectrophotometer and are given as λmax (nm), [ꢀ (M
(
2
2
2
6
H
6
2
-1
cm )], sh ) shoulder. IR spectra (Nujol mulls, KBr plates) were
recorded (cm ) on an ATI Mattson Genesis FTIR spectrometer (s )
2
3
2
.
-1
2
0
),21 cis-RuCl
2
(PPh
)
3 3
,
RuCl
2
(dppb)(PPh
3
2
-
-
strong). Elemental analyses were performed by Mr. P. Borda of the
UBC Chemistry department.
The procedure used to screen the activity of the Ru complexes for
1
1
22
(
dppb)(PPh
published procedures. PtI
cod) using a 5-fold excess of NaI (per chloride) in acetone. PPh
dppb were used as received from Aldrich. Ph P(py) was synthesized
and characterized as described previously, the synthesis being adapted
2
(py)) (12), and PtCl
2
(cod) were prepared according to
2
(cod) was prepared by metathesis of PtCl
2
(
3
and
H
2
hydrogenation of imines to amines, at 1000 psi H
sources of imines and amines, has been described elsewhere.
Racemic d(py)pcp. To Et O (100 mL) cooled to -77 °C in a dry
2
, including the
2
24
9
c
2
from a literature procedure. The ligand d(py)pe,3b trans-1,2-bis-
dichlorophosphino)cyclopentane ((Cl P) ) and racemic trans-1,2-
bis(diphenylphosphino)cyclopentane (dppcp) were prepared as described
23
n
ice/acetone bath, BuLi (100 mL, 160 mmol) was added by cannula,
and the mixture allowed to cool for 5 min. To this solution was added
(
2
2 5 8
C H
2
-bromopyridine (16 mL, 160 mmol) which caused an immediate color
change from pale yellow to brown-red. The cooled mixture on being
stirred for 4 h became deep red. trans-1,2-(Cl P) (7 mL, 40 mmol)
in Et O (30 mL) was then added dropwise over 15 min, and stirring
1
8f
in the literature.
The following reagents were used as supplied: nBuLi (1.6 M in
hexanes, Aldrich), NaBr (Anachemia Chemicals Ltd.), NaI (MCB), and
2
2 5 8
C H
2
NH
SO
CDCl
Cambridge Isotope Laboratories (CIL); CDCl
4
PF
(Fisher), and 2-bromopyridine (Aldrich). The deuterated solvents
, C , CD OD, CD Cl , and D O) were obtained from
and C were dried
6
(Ozark-Mahoning), NaOH (Fisher), concentrated HCl (Fisher),
was continued for 2 h at -77 °C. This resulted in the formation of a
brown suspension. The mixture was then allowed to warm to room
temperature (r.t.), whereupon the slurry was extracted with H SO
2 4
H
(
2
4
3
D
6 6
3
2
2
2
3
6 6
D
(
2 × 100 mL, 2 M) and the red aqueous layer was removed by cannula
over activated molecular sieves (Fisher: type 4 Å, 4-8 mesh),
deoxygenated, and stored under Ar.
from the yellow organic layer. The extract was neutralized by the
dropwise addition of saturated NaOH (∼35 mL) which resulted in the
formation of an “oily mass”. This mixture was filtered to yield a dark
orange grease which was re-suspended in acetone (60 mL) to give a
fine, white powder and red-brown filtrate. The solid was collected,
Solution NMR spectra were recorded on Varian XL300 (121.42 MHz
for 3 P{ H}, 75.429 MHz for C{ H}), Bruker AC200 (81.015 MHz
1
1
13
1
3
1
1
13
1
for P{ H}, 50.323 MHz for C{ H}), or Bruker AM400 spectrom-
1
31
1
eters; residual solvent proton ( H) or external P(OMe)
41.00 vs external 85% aq. H
3
1
( P{ H}: δ
washed with acetone (3 × 2 mL) and then thoroughly with H O (∼150
2
3
1
3
PO
4
) or solvent carbon ( C) was used
mL). Reprecipitation from acetone/hexanes yielded a cream-colored
as the reference (s ) singlet; d ) doublet; t ) triplet; qn ) quintet;
spt ) septet; m ) multiplet; br ) broad; p ) pseudo). The solution
solid which was collected and then dried under vacuum at 100 °C for
7
5
4
2 h. Yield: 6.28 g (35%). Anal. Calcd for C25
24 4 2
H N P : C, 67.87; H,
31
1
P{ H} NMR data for the Ru complexes are given in the Results and
1
.47; N, 12.66. Found: C, 67.86; H, 5.45; N 12.58. H NMR (C
6
6
D ,
1
Discussion section (Table 1). The H NMR data are presented in this
section for purposes of characterization; peak assignments for d(py)-
pcp and its dioxide, according to the numbering scheme shown in Chart
3
3
2
00 MHz, 20 °C): δ 1.74 (qn, 2H , JHH ) 5.3), 1.97 (m, 2H ), 2.38
2
1
2
3
3
(
3
m, 2H ), 3.90 (ddd, 2H , JHP ) 11.47, JHH(anti) ) 7.78, JHH(gauche)
)
)
7
3
3
7 3
.21), 6.47 (dd, 2H,
J
HH ) 4.8, JHH ) 7.6), 6.51 (dd, 2H,
J
HH
2
, were made on the basis of COSY experiments, chemical shift values,
3
6
5
5
4
.8, JHH ) 7.6), 6.87 (m, 4H ), 7.32 (m, 2H ), 7.46 (m, 2H ; this
13
and coupling constants. All J values are given in Hz. Peaks in the C-
pattern could be simulated with unassigned coupling constants of 7.7,
8
3
8 3
1
.9, and 1.8 Hz), 8.38 (pd, 2H, JHH ) 10.1), 8.49 (pd, 2H , JHH )
3
13
1
(
20) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth. 1970,
2, 237.
3
10.1). C{ H} NMR (50.323 MHz, CDCl , 20 °C): δ 25.1 (3, C ),
1
2
1
6
3
0.2 (3, C ), 39.1 (4, C ), 122.5 (2), 129.3 (8), 135.2 (4, C ), 149.8 (6,
(
21) (a) Joshi, A. M.; Thorburn, I. S.; Rettig, S. J.; James, B. R. Inorg.
Chim. Acta 1992, 198, 283. (b) Jung, C. W.; Garrou, P. E.; Hoffman,
P. R.; Caulton, K. G. Inorg. Chem. 1984, 23, 726.
8
4
31
1
C ) 162.9 (1, C ). P{ H} NMR (121.4 MHz, CDCl
3
, 20 °C): δ -2.2
(s). The diphosphine was made as a mixture of R,R- and S,S-
(
22) McDermott, J. X.; White, J. F.; Whitesides, G. M.; J. Am. Chem. Soc.
1976, 98, 6521.
(24) (a) Fogg, D. E.; James, B. R.; Kilner, M. Inorg. Chim. Acta 1994,
222, 85. (b) Fogg, D. E.; James, B. R. Chem. Ind. (Dekker) 1995, 62,
435.
(23) Kurtev, K.; Ribola, D.; Jones, R. A.; Cole-Hamilton, D. J.; Wilkinson,
G. J. Chem. Soc., Dalton Trans. 1980, 55.

Coordination Chemistry of 2-Pyridyldiphosphine Ligands
Inorganic Chemistry, Vol. 38, No. 18, 1999 3959
1
enantiomers, the chirality designators referring to the C atoms of the
cyclopentane backbone.
mL). The resulting cloudy mixture was stirred at r.t. for 75 min and
then filtered through Celite 545. The volume of the colorless filtrate
was reduced to ∼2 mL under vacuum, and the product, afforded as a
Racemic d(py)pcp(O)
d(py)pcp (160 mg, 0.36 mmol) in a flask open to the atmosphere was
added dropwise a 30% H solution (2 mL). The colorless solution
was stirred for 1 h, cooled on ice, and then made basic using a saturated
KOH solution. The aqueous phase was extracted with CH Cl
(3 × 25
mL) and the combined organic fractions dried over MgSO . This
mixture was filtered and the filtrate reduced to ∼2 mL under reduced
pressure. Et O (30 mL) was then added to afford the product as a white
precipitate, which was collected, washed with Et
O (3 × 3 mL), and
dried in vacuo. Yield: 91 mg (53%). Anal. Calcd for C25
C, 63.29; H, 5.10; N, 11.81. Found: C, 63.11; H, 5.13; N 11.82. H
NMR (300 MHz, D O, 20 °C): δ 1.55 (m, 2H, CH ), 1.70 (br m, 2H,
CH ), 1.92 (br m, 2H, CH ), 3.64 (br m, 2H, CH), 7.15 (m, 2H, py),
.32 (m, 2H, py), 7.62 (br m, 4H, py), 7.71 (br m, 4H, py), 7.90 (pd,
2
. To a 0.2 M HCl solution (15 mL) containing
2
white precipitate by the addition of Et O (20 mL), was isolated by
O
2 2
filtration and dried overnight in vacuo. Yield: 39 mg (73%). Anal.
Calcd for C50 Pt: C, 43.27; H, 3.78; N, 8.07. Found: C,
43.07; H, 3.60; N, 8.00. H NMR (400 MHz, CDCl
(br m, 4H, CH ), 1.72 (m, 4H, CH ), 2.13 (m, 4H, CH
CH), 7.15-8.75 (m, 32H, py). P{ H} NMR (81.015 MHz, CDCl
50 8 6
H N F12OP
1
2
2
3
, 20 °C): δ 1.27
), 3.45 (m, 4H,
4
2
2
2
31
1
3
,
1
1
2
20 °C): δ 18.35 (s, JPPt ≈ 2400), 18.44 (s, JPPt ) 2404), -144 (spt,
PF ) 712, PF ).
[Pt(d(py)pe) ][PF
1
-
6
2
J
H
24
N
4
O
2
P
2
:
2
6
]
2
, 6. An impure sample of [Pt(d(py)pe)
2 2
]Cl (50
1
mg, ∼47 µmol, see above) and NH
4
PF (16 mg, 98 µmol) were
6
2
2
dissolved in acetone (20 mL), and the resulting cloudy solution was
stirred for 30 min; the mixture was filtered through Celite 545 which
was subsequently washed with acetone (3 × 5 mL) and the combined
filtrate reduced to ∼2 mL. The product was afforded as a white
2
2
7
2
°
1
2
1
3
1
3
H, py), 8.45 (pd, 2H, py). C{ H} NMR (CDCl , 75.429 MHz, 20
C): δ 26.2 (1, C ), 28.8 (1, C ), 35.0 (2, C ), 124.7 (2), 128.2 (5),
35.5 (2, C ), 150.0 (5, C ), 168.2 (1, C ). P{ H} NMR (121.4 MHz,
3
2
2
2
precipitate by the addition of Et O (30 mL), isolated by filtration,
6
8
4
31
1
washed with Et
Anal. Calcd for C50
C, 40.82; H, 2.98; N, 8.51. H NMR (300 MHz, CD
2
O (3 × 5 mL), and dried in vacuo. Yield: 42 mg (77%).
-
1
0 °C): δ 35.8 (s) [CDCl
cis-PtCl (d(py)pcp), 1. A CH
mg, 0.24 mmol) was added dropwise via cannula over 5 min to a CH
Cl (5 mL) solution of PtCl (cod) (93 mg, 0.25 mmol). The resulting
3
]; 38.7 (s) [D
2
O]. IR: νPO ) 1194 cm
.
48 8 12 6
H N F P
Pt: C, 40.98; H, 3.13; N, 8.69. Found:
1
2
2
Cl (10 mL) solution of d(py)pcp (104
2
3
OD, 20 °C): δ
), 5.7-7.1 (m, 32H, py). P{ H} NMR (81.015 MHz,
31
1
2
-
1.30 (m, 8H, CH
CD OD, 20 °C): δ 54.42 (s, JPPt ) 2477), -144 (spt, JPF ) 712,
2
1
1
2
2
3
-
colorless solution was stirred for 1 h, and the volume was then reduced
PF
6
).
RuCl
7b‚H O (“fac-Isomer”). A 1 equiv amount of d(py)pcp (230 mg, 0.52
mmol) was added to a CH Cl (20 mL) solution of RuCl (PPh (500
to ∼2 mL. The product was afforded as a fine white precipitate by the
2 3 2 2
(P,P,N-d(py)pcp)(PPh )‚H O, 7a‚H O (“mer-Isomer”) and
addition of Et
2
O (30 mL), isolated by filtration, and washed with Et
2
O
2
(
°
3 × 5 mL). Reprecipitation from CH
2
Cl
C yielded pure product. Yield: 144 mg (86%). Anal. Calcd for
Cl Pt: C, 42.38; H, 3.47; N, 7.91. Found: C, 42.62; H,
.40; N, 7.64. H NMR (200 MHz, CDCl
CH ), 2.1 (m, 4H, CH ), 3.6 (pt, 2H, CH), 7.3-8.8 (m, 16H, py). P-
H} NMR (81.015 MHz, CDCl
cis-PtI (d(py)pcp), 2. Preparation of 2 in the same manner as that
outlined for 1 yielded, in addition, a small quantity of [Pt(d(py)pcp) ]-
, as determined by 3 P{ H} NMR spectroscopy (see 5 below). This
contaminant was removed by washing the product with dilute HCl (∼50
mL). Thus, reaction of PtI (cod) (100 mg, 0.18 mmol) and d(py)pcp
79 mg, 0.18 mmol) yielded 129 mg (80%) of a yellow powder. Anal.
Calcd for 2, C25 Pt: C, 33.69; H, 2.71; N, 6.29. Found: C,
4.08; H, 2.72; N, 6.00. H NMR (300 MHz, CDCl
m, 2H, CH ), 1.75 (m, 2H, CH ), 2.10 (m, 2H, CH
CH), 7.3-8.8 (m, 16H, py). P{ H} NMR (121.4 MHz, CDCl
2
and drying in vacuo at 100
2
2
2
3 3
)
mg, 0.52 mmol) and the resulting dark brown mixture stirred at r.t.
After 20 min, the dark orange solution was reduced to dryness and the
residue taken up in a 1:1 mixture of CH Cl and C H (10 mL). Hexanes
2 2 6 6
C
3
25
H N
24 4
2 2
P
1
3
, 20 °C): δ 1.6 (m, 2H,
31
2
2
(10 mL) were added to precipitate the yellow-orange product, which
was collected, washed with hexanes (3 × 5 mL), and dried under
vacuum at 100 °C. The solid was shown by 31P{ H} NMR spectroscopy
1
1
{
3
, 20 °C): δ 17.86 (s, JPPt ) 3493).
1
2
2
(see Table 1) to be complex 7b‚H
for C43 Cl OP Ru: C, 57.72; H, 4.62; N, 6.26. Found: C, 57.97;
H, 4.54; N, 6.13. H NMR of 7b (300 MHz, CDCl
(br m, 1H, CH), 1.36 (m, 2H, CH ), 1.56 (s, H O), 1.95 (m, 2H, CH
2.42 (br m, 1H, CH ), 2.68 (br m, 1H, CH ), 3.62 (br m, 1H, CH),
6.8-8.6 (m, 31H, py and Ph). UV-vis (CH Cl ): 344 [3090], 420
[1670]. P{ H} NMR spectroscopy showed that 7a constituted a small
fraction of the dissolved Ru in the CH Cl /C /hexanes filtrate; by
slow evaporation of this mixture a bright orange crystal of 7a‚2CH
Cl was isolated. Subsequently, an X-ray diffraction quality orange
crystal of the major isomer (7b) was isolated as 7b‚1.5EtOH from a
CH Cl solution of the complex which had been layered with EtOH.
2
O. Yield: 0.31 g (67%). Anal. Calcd
1
1
I
2
H N
41 4
2
3
1
3
, 20 °C): δ 0.24
),
2
2
2
2
(
2
2
H N
24 4
I
2
P
2
1
2
2
31
1
3
3
, 20 °C): δ 1.55
), 3.65 (2H, m,
, 20
were isolated
solution of 2 onto which Et O had been
(
2
2
2
2
2
6 6
H
3
1
1
3
2
-
1
°
C): δ 12.57 (s, JPPt ) 3294). Crystals of 2‚0.18 CH
2
Cl
2
2
after 72 h from a CH
layered.
2
Cl
2
2
2
2
1
cis-PtCl
as 1, except that the product was washed with MeOH instead of Et
Reaction of PtCl (cod) (225 mg, 0.60 mmol) and d(py)pe (243 mg,
.60 mmol) yielded 300 mg (70%) of a white powder. Anal. Calcd for
Cl Pt: C, 39.54; H, 3.02; N, 8.38. Found: C, 39.74; H,
.00; N, 8.10. H NMR (300 MHz, CDCl
2
(d(py)pe), 3. Compound 3 was prepared in the same manner
Assignment of the H NMR spectrum of 7a was impossible due to
overlapping resonances of 7b.
2
O.
2
A mixture of 7a and 7b hydrates can also be prepared by stirring
0
the two reactants in C
RuBr (P,P,N-d(py)pcp)(PPh
mmol) was added to an acetone solution (10 mL) of 7b‚H
6
D
6
at r.t. for 3 h.
)‚H O, 8. Excess NaBr (140 mg, 1.4
O (52 mg,
C
3
22
H N
20 4
P
2 2
2
3
2
1
3
, 20 °C): δ 2.9 (m, 4H,
2
3
1
1
CH
2
2
), 7.4-8.7 (m, 16H, pyridyl). P{ H} NMR (121.4 MHz, CDCl
0 °C): δ 47.08 (s, JPPt ) 3481). Colorless crystals of 3‚CH Cl
2
3
,
0.058 mmol) and the resulting cloudy yellow-orange suspension stirred
for 24 h at r.t. The mixture was pumped to dryness and the orange-
1
2
,
suitable for study by X-ray diffraction, were isolated after 24 h from a
CH Cl solution of 3, which had been layered with Et O.
cis-PtI (d(py)pe), 4. Compound 4 was prepared in the same manner
as 1. Reaction of PtI (cod) (71 mg, 0.13 mmol) and d(py)pe (51 mg,
.13 mmol) yielded 50 mg (46%) of a yellow powder. Anal. Calcd for
Pt: C, 31.04; H, 2.37; N, 6.58. Found: C, 31.17; H, 2.44;
N, 6.35. H NMR (300 MHz, CD Cl , 20 °C) δ 2.73 (m, 4H, CH ),
, 20 °C) δ
brown residue dissolved in CH
2
Cl
2
; this was then filtered through Celite
O (20 mL) and
2
2
2
545, and the solution reduced in volume to ∼3 mL. Et
2
2
hexanes (10 mL) were added to precipitate the orange product which
2
was collected, washed with hexanes (2 × 3 mL), and dried under
0
C
41 4 2 3
vacuum. Yield: 39 mg (67%). Anal. Calcd for C43H N Br OP Ru:
1
22
H
20
N
4
I
2
P
2
C, 52.51; H, 4.20; N, 5.70. Found: C, 52.64; H, 4.14; N, 5.54. H
NMR (300 MHz, CDCl , 20 °C): δ 0.10 (m, 1H, CH), 1.40 (m, 2H,
CH ), 1.56 (s, H O), 1.90 (m, 2H, CH ), 2.30 (br m, 1H, CH ), 2.64
(br m, 1H, CH ), 3.65 (br m, 1H, CH), 6.7-8.7 (m, 31H, py and Ph).
UV-vis (CH Cl ): 350 [2320], 430 [1370].
RuI (P,P,N-d(py)pcp)(PPh )‚H O, 9. Excess NaI (140 mg, 0.93
mmol) was added to an acetone solution (10 mL) of 7b‚H O (41 mg,
1
2
2
2
3
3
1
1
7
4
.25-8.85 (m, 16H, py). P{ H} NMR (121.4 MHz, CDCl
3
2
2
2
2
1
9.84 (s, JPPt ) 3397).
2
Preparations of the compounds [Pt(L)
X ) Cl, I) either by reaction of 2 equiv of the ligand with PtX
in CH Cl or, in the case of the iodide salts, by metathesis of [Pt(L)
Cl with NaI in acetone, were successful as determined by H and P-
2
]X
2
(L ) d(py)pe, d(py)pcp;
(cod)
]-
2
2
2
2
3
2
2
2
2
31
2
1
2
0.046 mmol) and the resulting cloudy orange suspension stirred for 18
h at r.t. The mixture was pumped to dryness and the orange-brown
1
{
H} NMR spectroscopies. However, satisfactory elemental analyses
were not obtained for these complexes.
Pt(d(py)pcp) ][PF ‚H O, 5‚H O. To a Schlenk tube charged with
PtCl (cod) (14.1 mg, 38 µmol), d(py)pcp (34.0 mg, 77 µmol) and NH
PF (12.7 mg, 78 µmol) were added CH Cl (3 mL) and acetone (4
residue dissolved in CH
545, and the solution reduced in volume to ∼3 mL. Et
added to precipitate the orange product which was collected, washed
with Et O (5 mL), and dried under vacuum. Yield: 29 mg (67%). Anal.
2
Cl
2
(10 mL); this was filtered through Celite
[
2
]
6 2
2
2
2
O (20 mL) was
2
4
-
6
2
2
2

3960 Inorganic Chemistry, Vol. 38, No. 18, 1999
Jones et al.
Table 2. Crystallographic Data
d(py)pe
2‚0.18CH
2
Cl
2
3‚CH
2
Cl
2
7a‚2CH
2
Cl
2
7b‚1.5EtOH
Cl
12
formula
fw
crystal system monoclinic
space group
a, Å
b, Å
C
22
H N
20 4
P
2
C
25.18 24.36 4
H N Cl0.36
I
2 2
P Pt
C
23
H
22
N
4
Cl
4
P
2
Pt
C
45
H N
43 4
Cl
P
6 3
Ru
C
46
H
48
N
4
2
O
1.5
P
3
Ru
47.5 2.5 3
C H42NCl9.5D P Ru
402.37
906.63
monoclinic
/n (No. 14) P2 /c (No. 14)
753.30
monoclinic
P2 /n (No. 14)
8.452(2)
16.351(4)
19.794(2)
90
97.49(1)
90
2712.1(8)
4
1046.51
triclinic
945.76
triclinic
1162.68
triclinic
P 1h (No. 2)
11.905(2)
19.210(2)
11.569(1)
98.795(2)
104.042(1)
78.148(4)
2496.9(5)
2
P2
1
1
1
P 1h (No. 2)
10.413(1)
12.457(1)
19.298(1)
78.896(1)
88.024(1)
65.951(1)
2256.53(6)
2
P 1h (No. 2)
12.187(1)
17.432(1)
21.024(1)
97.882(1)
91.845(1)
95.422(1)
4399.7(4)
4
11.615(1)
5.800(3)
15.538(2)
90
106.465(7)
90
1003.8(5)
2
1.331
17.359(1)
19.207(1)
19.287(1)
90
110.464(1)
90
6024.6(6)
8
1.999
c, Å
R, deg
â, deg
γ, deg
3
V, Å
Z
D
calc, g/cm3
1.845
1.549
1.428
1.546
T, °C
λ, Å
µ, cm
R
21
0.710 69
2.25
0.049
0.048
-93
21
-100
-100
-93
0.710 69
68.48
0.710 69
56.85a
0.031
0.710 69
8.52
0.710 69
6.28
0.710 69
9.53 b
-
1
a
a
b
b
0.048
0.050
0.0456
0.0541
0.058
a
a
0.029a
0.0913b
0.1115b
0.098b
R
w
a
2
2
1/2
b
R ) ∑(|F
o
| - |F
c
|)/∑|F
o
|, R
w
) [∑w(|F
o
| - |F
c
|) /∑w|F
o
| ] (based on reflections with I > 3σ(I)). R ) ∑(|F
o
| - |F
c
|)/∑|F | (based on
c
2
2
2
2 1/2
reflections with I > nσ(I), n ) 2 for 7a and 7b, n ) 3 for 12), R
w
) [∑w(|F
o
| - |F
c
|) /∑w|F
o
| ] (based on all data).
Calcd for C43
7.97; H, 3.82; N, 5.04. H NMR (200 MHz, CDCl
m, 1H, CH), 1.30 (m, 2H, CH ), 1.56 (s, H O), 1.85 (m, 2H, CH
), 2.62 (br m, 1H, CH ), 3.64 (br m, 1H, CH),
.7-8.9 (m, 31H, py and Ph). UV-vis (CH Cl ): 360 [4000], 452
H
41
N
4
I
2
OP
3
1
Ru: C, 47.93; H, 3.83; N, 5.20. Found: C,
2θ ) 15.1-27.4° for d(py)pe, 37963 reflections with 2θ ) 4.0-60.4°
for 2, 25 reflections with 2θ ) 20.9-30.6° for 3, 6925 reflections with
2θ ) 2.16-50.06° for 7a, 5711 reflections with 2θ ) 1.96-50.12°
for 7b, and 17 370 reflections with 2θ ) 4.0-60.1° for 12. The
intensities of three standard reflections, measured every 200 reflections
throughout the data collections for d(py)pe and 3, decreased linearly
4
(
2
6
[
3
, 20 °C): δ 0.10
),
2
2
2
.15 (br m, 1H, CH
2
2
2
2
2160].
trans-RuCl
mmol) and dppcp (120 mg, 0.27 mmol) were dissolved in CH
25,26
2
(dppcp)
2
, 10. Method 1. RuCl
2
(PPh
)
3 3
(260 mg, 0.27
Cl (10
by 3.2% and 16.3%, respectively. The data were processed,
corrected
2
2
for Lorentz and polarization effects, decay (for d(py)pe, 2 and 3), and
absorption (empirical, based on azimuthal scans for d(py)pe and 3,
semiempirical for 7a, SADABS for 7b, and fourth-order spherical
harmonics for 12).
The structure analysis of 12 was initiated in the centrosymmetric
space group P on the basis of the E statistics, this choice being
confirmed by subsequent calculations. The structures of 2, 3, and 12
were determined by the Patterson method and those of d(py)pe, 7a,
and 7b were determined by direct methods. The d(py)pe molecule lies
on a crystallographic center of symmetry. There are two independent
mL) and the solution stirred at r.t. After 2 h, the brown suspension
was concentrated ∼5 mL and EtOH (10 mL) was added to precipitate
a beige solid which was collected, washed with EtOH (2 × 5 mL),
and dried under vacuum. Yield: 50 mg (36% based on phosphine).
The initial aim of this procedure was to prepare the complex RuCl
dppcp)(PPh ), and thus only 1 equiv of the phosphine was used. The
excess RuCl (PPh remained in solution (and was separated from the
2
-
(
3
2
3 3
)
product by filtration); the yield would certainly have been improved
by using two equivs of phosphine.
Method 2. 10 could be prepared more conveniently by refluxing an
molecules, and a partial CH
The asymmetric unit of 3 contains one metal complex and one CH
molecule, while that of 7a contains one metal complex and two CH
Cl
molecules of CDCl
disordered about an inversion center, one is ordered in a general
position, and the third is (1:1) 2-fold disordered with respect to rotation
about the C-D bond. The asymmetric unit of 7b consists of two Ru
complexes and three EtOH molecules.
Some half-occupancy non-hydrogen atoms in 12 (Cl(9), Cl(12), and
C(47)) were refined with isotropic thermal parameters because the
anisotropic thermal parameters were nonpositive-definite. All remaining
non-hydrogen atoms were refined with anisotropic thermal parameters.
The hydrogen atom positions of d(py)pe, 2, 3, and 12 were fixed in
2 2
Cl molecule, in the asymmetric unit of 2.
EtOH (25 mL) solution of RuCl
3
‚xH
2
O (250 mg, 1.0 mmol, 41.50%
2
Cl
2
Ru) and dppcp (930 mg, 2.1 mmol) for 5 h. The resulting light-colored
preciptate was collected, washed with EtOH (10 mL), and dried under
2
-
2
molecules, and that of 12 consists of one metal complex and 2.5
. One of the CDCl molecules in 12 is (1:1)
vacuum. Yield: 710 mg (67%). Anal. Calcd for C58
6.41; H, 5.38; Cl, 6.76. Found: C, 66.16; H, 5.36; Cl, 7.03. H NMR
300 MHz, CDCl , 20 °C): δ 0.55 (br m, 2H, CH ), 1.30 (br m, 4H,
), 1.62 (br m, 4H, CH ), 1.83 (br m, 2H, CH ), 3.55 (br m, 4H,
H56Cl
2
P
4
1
Ru: C,
3
3
6
(
3
2
CH
2
2
2
CH), 6.80-7.90 (m, 40H, Ph).
trans-RuCl (dppb)(dppcp), 11. To a C
RuCl (dppb)(PPh ) (220 mg, 0.25 mmol) was added dppcp (120 mg,
.27 mmol), and the resulting solution was stirred at 20 °C for 1 h.
2
H
6 6
(30 mL) solution of
2
3
0
The orange-brown solution was reduced in volume to ∼5 mL, and
hexanes (35 mL) were then added to precipitate a beige solid, which
was collected, washed with hexanes (3 × 5 mL), and dried under
calculated positions (C-H ) 0.98 Å, B
H
) 1.2Bbonded atom). The
vacuum. Yield: 190 mg (73%). Anal. Calcd for C57
H56Cl
2
P
4
1
Ru: C,
hydrogen atoms for 7a and 7b were placed in ideal positions and refined
as riding atoms with individual (or group if appropriate) isotropic dis-
placement parameters. Corrections for secondary extinction (Zachariasen
type, isotropic) were applied where necessary, the final values of the
6
(
6.02; H, 5.44; Cl, 6.84. Found: C, 66.23; H, 5.60; Cl, 7.00. H NMR
300 MHz, CHCl , 20 °C): δ 0.65 (br m, 2H, CH of dppcp), 1.32 (br
of dppb), 2.12 (br m, 2H, CH of dppcp), 2.19 (br m, 2H,
of dppb), 2.69 (br m, 2H, CH of
dppb), 3.45 (br m, 2H, CH of dppcp), 6.42-8.02 (m, 40H, Ph).
RuCl (dppb)(P,N-PPh (py))‚2.5CDCl , 12. Orange crystals of 12
were isolated, after several months at r.t., from an NMR tube containing
a CDCl solution of the complex which had been prepared according
3
2
m, 4H, CH
2
2
-
6
CH
2
of dppcp), 2.25 (br m, 2H, CH
2
2
extinction coefficients being 6.6(3) × 10 for d(py)pe and 6.2(15) ×
-7
10 for 3. Neutral atom scattering factors for all atoms and anomalous
dispersion corrections for the non-hydrogen atoms were taken from
the International Tables for Crystallography.27
2
2
3
3
to ref 11. The structure is included here because of its similarity to
those of 7b, 8, and 9, with a fac-arrangement of P atoms.
X-ray Crystallographic Analyses. The solvate molecules associated
with each structure are omitted in this section for ease of reading; e.g.
(25) teXsan: Crystal Structure Analysis Package; Molecular Structure
Corporation: The Woodlands, TX, 1997.
26) d*trek: Area Detector Software; Molecular Structure Corporation: The
Woodlands, TX, 1997.
(
(
27) (a) International Tables for X-ray Crystallography; Kynoch Press:
Birmingham, England, 1974; Vol. IV, pp 99-102. (b) International
Tables for Crystallography; Kluwer Academic Publishers: Boston,
1992; Vol. C, pp 200-206.
2
‚0.18 CH
Crystallographic data appear in Table 2. The final unit-cell param-
eters were obtained by least-squares based on 25 reflections with
2 2
Cl is written simply as 2.

Coordination Chemistry of 2-Pyridyldiphosphine Ligands
Selected bond lengths and bond angles for d(py)pe and the complexes
Inorganic Chemistry, Vol. 38, No. 18, 1999 3961
Chart 3
2
, 3, 7a, 7b, and 12 appear in Tables 3-8, respectively. A complete
table of crystallographic data, atomic coordinates and equivalent
isotropic thermal parameters, complete tables of bond lengths and bond
angles, anisotropic thermal parameters, torsion angles, and intermo-
lecular contacts for the six structures are included as Supporting
Information.
Results and Discussion
Syntheses. rac-d(py)pcp and its Dioxide. The racemic d(py)-
pcp compound was made via treatment of trans-1,2-Cl2P-
(
CH(CH2)3CH)PCl218f with 2-lithiopyridine which itself was
3b
formed in situ from 2-bromopyridine. The dioxide (py)2P(O)-
(
CH(CH2)3CH)P(O)(py)2 (d(py)pcp(O)2) was synthesized (as a
31
racemate) to establish, by P NMR spectroscopy, the absence
of this compound as a possible impurity in the complexes here
under study (particularly those of Ru).
resulting from bonding via an N atom; this presumably prevents
coordination of a second d(py)pcp ligand. The initially isolated
complexes 7a, 7b, 8, and 9, of the type RuX2(P,P,N-d(py)pcp)
Platinum Complexes. A scheme for the numbering of
platinum complexes with the general empirical formula Pt-
(
P-P)nX2 (n ) 1, 2; P-P ) d(py)pe, d(py)pcp; X ) Cl, I,
(
X ) halogen), all contain one solvated H2O molecule as
PF6) is given below.
1
evidenced by H NMR spectroscopy and analytical data. This
solvate could not be removed by drying the compounds in vacuo
at 100 °C, although crystals of 7a and 7b were grown containing
solvate CH2Cl2 or EtOH, respectively. Complex 12 (cis-RuCl2-
P-P ) d(py)pcp
P-P ) d(py)pe
n ) 1, X ) Cl
n ) 1, X ) I
n ) 2, X ) PF
1
2
5
3
4
6
(dppb)(P,N-PPh2(py)) had been synthesized previously from the
6
trans-isomer, itself made from the reaction of RuCl2(dppb)-
1
1
(PPh3) and PPh2(py).
Addition of 1 equiv of d(py)pe or d(py)pcp to PtX2(cod)
The reaction of 1 equiv of d(py)pe with RuCl2(PPh3)3 in C6H6
(X ) Cl, I) results in the rapid formation of the P,P-bonded
yields a number of products whose structures are not yet known,
and investigation into this reaction is currently underway.
complexes PtX2(P-P), although in the case of X ) I, a small
amount of [Pt(P-P)2]I2 is also produced; such ionic species [Pt-
31
1
Solution P{ H} NMR Spectra. Platinum Complexes. The
(P-P)2]X2 are also readily synthesized. Studies on the solubili-
3
1
singlet P chemical shifts for complexes 1-4 fall in the
ties of the pyridylphosphine ligands and the Pt and Ru
complexes, and their aqueous solution chemistry (including
associated pKa values) are in progress.
downfield regime, consistent with the reported relative deshield-
30
1
ing of P nuclei in five-membered chelate rings. The JPPt values
are in the range expected for P nuclei in a cis disposition31 and
2
1a,28
Ruthenium Complexes. Earlier work from this group
and elsewhere21b has shown that the five-coordinate RuCl2-
singlets imply a C symmetry. The two singlets of roughly equal
2
intensity seen for 5 are attributed to the presence of diastere-
(P-P)(PPh3) species (P-P ) dppb, binap, diop) can be made
omers containing combinations of the R,R or S,S ligand.
by reaction of 1 equiv of the diphosphine with RuCl2(PPh3)3.
The corresponding reaction with racemic dppcp in this study
gives rise to trans-RuCl2(dppcp)2 (10) rather than RuCl2(dppcp)-
3
1
1
Ruthenium Complexes. The P{ H} NMR data at r.t. for
complexes 7-12 are given in Table 1. The mer and fac labels,
used for convenience, refer to the arrangement of the three
coordinated P atoms. Representations of the structures are shown
in Chart 3.
PPh3), which is preferred for catalytic studies.21a,24,29 This is
(
in accord with the usual finding that the reaction of RuCl2(PPh3)3
with 1 equiv of the shorter carbon backbone diphosphines Ph2P-
In CDCl3, with the exception of 7b, the complexes containing
P atoms in a fac arrangement give rise to ABX or AMX patterns,
(
CH2)nPPh2 (n ) 1-3) gives rise only to species of the type
RuCl2(P-P)2, while reaction with diphosphines that form a
seven-membered chelate (dppb, binap, diop) yields RuCl2-
2
with diagnostically small JPP values (∼30 Hz) indicative of
2
1,28
mutually cis P atoms. On the basis of integration, the downfield
resonances for 7-9 are attributed to the d(py)pcp ligand and
the more upfield one to PPh3. Complex 7a displays two smaller
(P-P)(PPh3).
This has been attributed to the smaller bite
angle of the former set of ligands which leaves the Ru center
less sterically crowded and more susceptible to attack by a
second diphosphine molecule. The presence of only a single
C2 backbone diphosphine ligand in a Ru(II) complex can be
enforced by appropriate choice of the Ru(II) precursor. Thus,
in the 1:1 reaction of RuCl2(dppb)(PPh3) with dppcp, the
complex trans-RuCl2(dppb)(dppcp) (11) is formed.
In the reaction of RuCl2(PPh3)3 with 1 equiv of d(py)pcp, a
two-carbon backbone phosphine which differs from dppcp only
in the presence of 2-pyridyl rather than phenyl rings bound to
the P atoms, the availability of pyridyl N atoms allows for
bonding of just a single d(py)pcp unit, with six-coordination
2
JPP values and one larger, consistent with two cis and one trans
coupling constant, i.e., with a mer arrangement of the P atoms,
as found in the solid-state structure (vide infra).
3
1
1
The P{ H} NMR spectrum of 7b in CDCl3 at r.t. shows an
A2X triplet and doublet pattern with a coupling constant
indicative of three mutually cis P atoms (Table 1). The data are
consistent with the following solution structures (i) 5-coordinate
(square pyramid) geometry in which d(py)pcp acts as a
4-electron P,P donor, (ii) 6-coordinate geometry in which d(py)-
pcp again acts as a P,P donor and H2O is bound in the axial
site trans to PPh3 (and note that 7b is isolated as a monohydrate),
(
28) MacFarlane, K. S.; Joshi, A. M.; Rettig, S. J.; James, B. R. Inorg.
Chem. 1996, 35, 7304.
(30) Dixon, K. R. In Multinuclear NMR; Mason, J., Ed.; Plenum: New
York, 1987; Chapter 13.
(31) Grim, S. O.; Keiter, R. L.; McFarlane, W. Inorg. Chem. 1967, 6, 1133.
(29) MacFarlane, K. S.; Thorburn, I. S.; Cyr, P. W.; Chau, D. E. K.-Y.;
Rettig, S. J.; James, B. R. Inorg. Chim. Acta 1998, 270, 130.

3962 Inorganic Chemistry, Vol. 38, No. 18, 1999
Jones et al.
Figure 2. ORTEP representation of d(py)pe. Thermal ellipsoids for
non-hydrogen atoms are drawn at 30% probability.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for d(py)pe
with Estimated Standard Deviations in Parentheses
P(1)-C(1)
P(1)-C(7)
N(1)-C(6)
N(2)-C(11)
1.842(3)
1.850(3)
1.342(4)
1.338(4)
P(1)-C(2)
N(1)-C(2)
N(2)-C(7)
a
1.846(3)
1.346(4)
1.334(4)
1.527(6)
Figure 1. 31P{ H} NMR spectrum (121.4 MHz, 20 °C) of trans-RuCl
1
2
-
(
dppb)(dppcp) (11) in CDCl
spectrum (AA′BB′) obtained using the parameters listed in Table 1.
3
; (a) recorded spectrum and (b) simulated
C(1)-C(1)
C-C in py rings 1.360(5)-1.384(4)
C(1)-P(1)-C(2)
C(2)-P(1)-C(7)
C(7)-N(2)-C(11)
P(1)-C(2)-N(1)
N(1)-C(2)-C(3)
P(1)-C(7)-N(2)
N(2)-C(7)-C(8)
101.7(1)
98.1(1)
116.6(3)
112.7(2)
121.8(3)
119.9(2)
122.5(3)
C(1)-P(1)-C(7)
C(2)-N(1)-C(6)
P(1)-C(1)-C(1)
P(1)-C(2)-C(3)
N(1)-C(6)-C(5)
P(1)-C(7)-C(8)
N(2)-C(11)-C(10)
101.8(1)
116.9(3)
110.4(3)
125.4(3)
124.6(3)
117.6(3)
124.6(4)
or (iii) 6-coordinate geometry in which d(py)pcp acts as a
a
6
-electron P,P,N donor whose P atoms are rendered equivalent
on the NMR time scale by an exchangeable, labile N atom. At
40 °C the spectrum shows the same triplet at 8.8 ppm as
-
observed at r.t., and a 6-line pattern centered at the position of
the doublet in the r.t. spectrum (47.8 ppm), which appears to
be a superimposition of two triplets (as observed for 7b at r.t.
C-C-C in py rings 117.6(3)-119.9(4)
a
2
Symmetry operation: 1 - x, 1 - y, -z.
in C6D6 and with the same JPP) and the “r.t. doublet”. The
corresponding -20 °C spectrum is intermediate between those
at r.t. and -40 °C; it shows an enhanced “r.t. doublet”
overlapped with a diminished pair of triplets centered at 47.8
ppm, as well as the triplet at 8.8 ppm. This rules out possibility
molecules associated with the structures are excluded from the
number designators of the complexes. The molecular structure
of d(py)pe shows C2 symmetry (Figure 2, Table 3). The
P-C(CH2) bond length of 1.842 Å is essentially identical to
the average P-C(CH2) bond length reported for dppe coordi-
nated to various metals (1.845 Å); however, the average
P-C(py) bond length (1.848 Å) is significantly longer than the
(iii) for the r.t. structure which necessitates that at an intermedi-
ate temperature, an averaged, broadened signal be observed.
Thus, the -20 °C spectrum most probably results from a slow
exchange between RuCl2(P,P,N-d(py)pcp)(PPh3) and RuCl2-
32
average P-C(Ph) reported for dppe complexes (1.827 Å). The
(P,P-d(py)pcp)(PPh3) (r.t. solution structure (i)) or between
average P-C(alkyl and aryl) bond length in free d(py)pe is
somewhat longer than the corresponding average found for the
ligand bound to Pt in 3 (1.846 vs 1.820 Å, respectively). In
contrast, the C-C “backbone” distances in the free and
coordinated ligands are essentially identical (1.527 and 1.531
Å, respectively). The P(1)-C(1)-C(1*) angles (110°), and the
various C-P-C angles (av. 101°) of free d(py)pe, become 109.5
and 108.5, and 106°, respectively, within 3 (Figure 3). The
structure of 3 shows only minor deviations from square-planar
geometry at the metal center; the relevant bond angles are shown
in Table 4. The d(py)pe forms a five-membered chelate ring
with Pt(II), through the two P atoms, with the ring atoms (Pt,
P(1), C(1), C(2), and P(2)) arranged in a twisted envelope
conformation. The average Pt-P bond length (2.210 Å) and
RuCl2(P,P,N-d(py)pcp)(PPh3) and RuCl2(P,P-d(py)pcp)(PPh3)-
(
H2O) (r.t. structure (ii)).
Of note, the r.t. 31P{ H} NMR spectrum of 7b in the less
1
polar solvent C6D6 shows an ABX pattern, consistent with the
formulation fac-RuCl2(P,P,N-d(py)pcp)(PPh3) as determined in
the solid-state (vide infra).
As with 5, complex 10 gives rise to two diastereomers as
evidenced by the two 31P{ H} NMR singlets which, in this case,
integrate to a ratio of ∼2:1. The greater abundance of one
diastereomer over the other is attributed to differences in
solubility between the two and not to any kinetic or thermo-
dynamic mechanism of diastereoselectivity.
1
Complex 11 gives rise to a second-order AA′BB′ pattern
which is simulated well by the parameters given in Table 1
(Figure 1).
(32) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
Molecular Structures. Again, for convenience, the solvate
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.

Coordination Chemistry of 2-Pyridyldiphosphine Ligands
Inorganic Chemistry, Vol. 38, No. 18, 1999 3963
Figure 3. ORTEP representation of cis-PtCl
Cl ). Thermal ellipsoids for non-hydrogen atoms are drawn at 33%
probability.
2
(d(py)pe)‚CH
2
Cl
2
2
(3‚CH -
2
Figure 4. ORTEP representation of one of the two crystallographically
2
independent molecules of cis-PtI (d(py)pcp) (2) in the asymmetric unit
(
50% probability ellipsoids).
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
‚CH Cl with Estimated Standard Deviations in Parentheses
3
2
2
Table 5. Selected Bond Lengths (Å) and Angles (deg) for 2‚0.18
CH Cl with Estimated Standard Deviations in Parentheses
Pt(1)-Cl(1)
Pt(1)-P(1)
2.359(2)
2.209(2)
P-C 1.810(6)-1.832(6)
Pt(1)-Cl(2)
Pt(1)-P(2)
2.348(2)
2.211(2)
2
2
Pt(1)-I(1)
Pt(1)-P(1)
Pt(2)-I(3)
Pt(2)-P(3)
C(1)-C(2)
2.639(1)
2.244(2)
2.651(1)
2.243(2)
1.480(1)
Pt(1)-I(2)
Pt(1)-P(2)
Pt(2)-I(4)
Pt(2)-P(4)
C(26)-C(27)
2.653(1)
2.247(2)
2.653(1)
2.248(2)
1.547(1)
Cl(1)-Pt(1)-Cl(2) 90.80(6)
Cl(1)-Pt(1)-P(1)
Cl(2)-Pt(1)-P(1)
177.19(6)
91.18(6)
86.17(6)
113.7(2)
106.9(3)
106.4(3)
109.5(4)
105.7(3)
115.5(2)
105.1(3)
Cl(1)-Pt(1)-P(2)
Cl(2)-Pt(1)-P(2)
Pt(1)-P(1)-C(1)
Pt(1)-P(1)-C(8)
C(1)-P(1)-C(8)
C(2)-C(1)-P(1)
C(2)-P(2)-C(13)
Pt(1)-P(2)-C(2)
Pt(1)-P(2)-C(18)
C(2)-P(2)-C(18)
P(1)-C(8)-N(2)
P(2)-C(18)-N(4)
91.87(6)
177.25(6) P(1)-Pt(1)-P(2)
108.6(2)
115.4(2)
105.3(3)
108.5(4)
105.1(3)
109.5(2)
115.6(2)
105.7(3)
114.1(5)
114.0(5)
Pt(1)-P(1)-C(3)
C(1)-P(1)-C(3)
C(3)-P(1)-C(8)
C(1)-C(2)-P(2)
C(2)-P(2)-C(18)
Pt(1)-P(2)-C(13)
C(2)-P(2)-C(13)
C(13)-P(2)-C(18) 104.5(3)
P(1)-C(3)-N(1)
P(2)-C(13)-N(3)
P-C 1.808(8)-1.839(8)
I(1)-Pt(1)-I(2)
I(1)-Pt(1)-P(2)
I(2)-Pt(1)-P(2)
I(3)-Pt(2)-I(4)
I(3)-Pt(2)-P(4)
I(4)-Pt(2)-P(4)
P(1)-C(6)-N(1)
P(2)-C(16)-N(3)
P(3)-C(31)-N(5)
P(4)-C(41)-N(7)
91.43(2)
92.08(5)
175.07(5)
92.38(2)
91.17(5)
176.15(5)
113.4(6)
115.0(6)
117.1(6)
112.2(5)
I(1)-Pt(1)-P(1)
176.18(5)
88.98(5)
87.75(7)
178.01(5)
89.38(5)
87.05(7)
117.6(5)
113.9(6)
111.0(6)
116.2(5)
I(2)-Pt(1)-P(1)
P(1)-Pt(1)-P(2)
I(3)-Pt(2)-P(3)
I(4)-Pt(2)-P(3)
P(3)-Pt(2)-P(4)
P(1)-C(11)-N(2)
P(2)-C(21)-N(4)
P(3)-C(36)-N(6)
P(4)-C(46)-N(8)
112.3(5)
114.3(5)
P-Pt-P angle (86.17°) are essentially identical with those
3
3
determined for cis-PtCl2(dppe) (2.208 Å and 86.3°).
The structure of 2 shows only slight deviations from square-
planar geometry at the metal center (Figure 4); the bond angles
and lengths for both crystallographically independent molecules
are shown in Table 5. The d(py)pcp forms a five-membered
chelate ring again with bonding via the two P atoms. The
chirality at the methine carbon atoms in the d(py)pcp ligand
backbone shown in Figure 4 is S,S, and the chelate ring is in
the δ configuration; the same is true for the second crystallo-
graphically independent molecule. The R,R enantiomers must
also be present in the unit cell, as racemic d(py)pcp was used
in the preparation of 2 which crystallized in the nonchiral space
group P21/c. The average Pt-P bond length (2.246 Å) is
somewhat longer than that observed in 3 (2.210 Å), perhaps
due to the stronger trans influence of iodide versus chloride,
although the comparison is drawn between two nonidentical
P-P ligand systems.
The structure of 7a (Figure 5, Table 6) is distorted from
octahedral coordination because of the four-membered P-N
chelate ring; for example, the N(1)-Ru(1)-P(2) bond angle is
a constrained 69.43°, while the P(2)-Ru(1)-Cl(1) bond angle
Figure 5. ORTEP representation of mer-RuCl
2 3
(P,P,N-d(py)pcp)(PPh )
(7a) (50% probability ellipsoids).
is relaxed to 104.70°, i.e., the P(2) atom is bent toward the N(1)
atom. The P-C-N(coordinated) angles for the four-membered
rings in 7a, 7b, and 12 are similar (100.5, 100.8, and 103.0°,
(
33) Farrar, D. H.; Ferguson, G. J. Crystallogr. Spectrosc. Res. 1982, 12,
465.

3964 Inorganic Chemistry, Vol. 38, No. 18, 1999
Jones et al.
Table 6. Selected Bond Lengths (Å) and Angles (deg) for
7
a‚2CH Cl with Estimated Standard Deviations in Parentheses
2
2
Ru(1)-N(1)
Ru(1)-P(1)
Ru(1)-C1(2)
2.078(3)
2.364(1)
2.443(1)
N-C 1.336(5)-1.364(5)
P-C 1.830(4)-1.858(4)
Ru(1)-P(2)
Ru(1)-P(3)
Ru(1)-Cl(1)
2.269(1)
2.394(1)
2.452(1)
N(1)-Ru(1)-P(2)
P(2)-Ru(1)-P(1)
P(2)-Ru(1)-P(3)
69.43(9)
82.26(4)
99.29(4)
N(1)-Ru(1)-P(1)
93.77(9)
89.85(9)
176.37(4)
N(1)-Ru(1)-P(3)
P(1)-Ru(1)-P(3)
N(1)-Ru(1)-Cl(2) 90.55(9)
P(2)-Ru(1)-Cl(2) 158.44(4)
P(3)-Ru(1)-Cl(2) 88.21(4)
P(1)-Ru(1)-Cl(1) 91.49(4)
N(1)-Ru(1)-Cl(1) 173.62(9) P(2)-Ru(1)-Cl(1) 104.70(4)
P(1)-Ru(1)-Cl(1)
P(1)-C(6B)-N(3)
P(2)-C(6A)-N(2)
82.76(4)
116.3(3)
112.7(3)
P(3)-Ru(1)-Cl(1) 93.66(4)
P(1)-C(1B)-N(4) 115.8(3)
P(2)-C(1A)-N(1) 100.5(3)
respectively) and are severely compressed when compared to
the values for the average P-C-N(free) angles of 114.6, 113.7,
1
16.3, 115.0, and 114.4° found in 2, 3, d(py)pe, 7a, and 7b,
respectively. Complex 7a displays a mer arrangement of the
three P atoms, and a cis disposition of the two Cl atoms, with
the coordinated pyridyl N atom trans to a Cl atom. The
coordinated P(1) atom of the d(py)pcp ligand bearing the two
noncoordinated pyridyl groups is trans to PPh3 and shows a
significantly longer Ru-P bond than the P(2) atom which is
trans to the lower trans influence Cl atom (2.3636 vs 2.2687
Å). The five-membered P-P chelate of d(py)pcp is in the λ
configuration.
On coordination of the N atom of the pyridyl group, the
associated P atom of d(py)pcp becomes chiral, and the ORTEP
(Figure 5) shows the S configuration. Furthermore, in the
preparation of 7a, a racemic (R,R and S,S) mixture of d(py)pcp
was used, while the ORTEP shows the R,R configuration. The
mirror image of the structure given in Figure 5, i.e., the R,S,S
enantiomer, is not shown, but the isolated crystal, belonging
again to the symmetric space group P, must contain one
molecule of each enantiomeric form in the unit cell. The R,R,R
and the S,S,S isomers were not crystallographically observed,
nor does the solution 31P{ H} NMR spectrum indicate the
presence of diastereomers.
1
The ORTEP of complex 7b (Figures 6a and b, Table 7)
evidences a distorted octahedral arrangement around the Ru
atom, again imposed by constraints of the four-membered P-N
chelate of the d(py)pcp ligand; the N(4)-Ru(1)-P(1) bond
angle is only 67.85° while the P(1)-Ru(1)-P(3) bond angle is
Figure 6. ORTEP representations of the two crystallographically
independent molecules of fac-RuCl (P,P,N-d(py)pcp)(PPh ) (7b) in the
2 3
asymmetric unit (50% probability ellipsoids); (a) and (b) show the S,S,S
and R,R,R diastereomers, respectively.
1
06.94°. Complexes 7a and 7b are structural isomers: both
display cis-chloro ligands, but in 7b the three P atoms are
arranged in a fac as opposed to the mer fashion seen in 7a, and
the ligand trans to the coordinated pyridyl N atom is PPh3 (vs
the Cl atom for 7a). The Ru-P bond lengths for the coordinated
d(py)pcp in 7b, with both P atoms being trans to Cl, are
essentially identical (2.2873 and 2.2863 Å). In addition, the Ru-
PPh3 bond length in 7b (2.3056 Å) is shorter than in 7a (2.3941
Å) because of the weaker trans influence of N with respect to
and S,R,R isomers were not crystallographically observed. In
2, 7a, and both crystallographically independent forms of 7b,
an R,R configuration of the ligand backbone enforces a λ
conformation in the five-membered P-P chelate ring, while the
S,S configuration enforces a δ conformation. However, the
absolute configuration at the P atom bearing the coordinated
pyridyl group has no effect upon the envelope conformation.
The distortion from octahedral geometry enforced by a four-
membered chelate is evidenced once more in the structure of
12 (Figure 7, Table 8). The P-N chelate ring of PPh2(py)
displays a N(1)-Ru(1)-P(3) angle of 68.0° and a P(1)-Ru-
(1)-P(3) angle of 101.1°, similar to the values found for the
corresponding angles in 7a and 7b. Although the ligand set in
12 is different, the three P atoms (two from dppb and one from
PPh2(py)) are also in a fac arrangement. The structure reported
here for 12 is consistent with the previously reported solution
3
1
P. The solid-state structure of 7b is consistent with the P-
1
{
H} NMR spectrum measured in C6D6 (see above). The unit
cell of 7b‚1.5EtOH contains two crystallographically indepen-
dent molecules of 7b which have marginally different geo-
metrical parameters (Table 7), and belongs to the centrosym-
metric space group P with a Z value of 4. This necessitates the
presence of both enantiomeric forms of each of the crystallo-
graphically independent molecules within the unit cell. The
ORTEP representations in Figure 6a and b correspond to the
S,S,S enantiomer of one independent molecule and the R,R,R
enantiomer of the other, respectively. In this instance, the R,S,S
3
1
1
structure, based on a P{ H} AMX pattern; the designators A
and M refer to the dppb P atoms, and X designates the PPh2-

Coordination Chemistry of 2-Pyridyldiphosphine Ligands
Inorganic Chemistry, Vol. 38, No. 18, 1999 3965
Table 7. Selected Bond Lengths (Å) and Angles (deg) for 7b‚1.5EtOH with Estimated Standard Deviations in Parentheses
Ru(1)-N(4)
Ru(1)-P(2)
Ru(1)-Cl(1)
2.141(4)
2.287(1)
2.455(1)
Ru(1)-P(1)
Ru(1)-P(3)
Ru(1)-Cl(2)
2.286(1)
2.306(1)
2.481(1)
P-C 1.825(5)-1.857(6)
N(4)-Ru(1)-P(1)
P(1)-Ru(1)-P(2)
P(1)-Ru(1)-P(3)
N(4)-Ru(1)-Cl(1)
P(2)-Ru(1)-Cl(1)
N(4)-Ru(1)-Cl(2)
P(2)-Ru(1)-Cl(2)
Cl(1)-Ru(1)-Cl(2)
P(1)-C(16)-N(3)
P(2)-C(6)-N(1)
67.85(11)
83.94(5)
106.94(5)
89.64(11)
92.33(5)
80.76(11)
170.63(5)
92.31(5)
115.5(4)
114.8(4)
N(4)-Ru(1)-P(2)
N(4)-Ru(1)-P(3)
P(2)-Ru(1)-P(3)
P(1)-Ru(1)-Cl(1)
P(3)-Ru(1)-Cl(1)
P(1)-Ru(1)-Cl(2)
P(3)-Ru(1)-Cl(2)
P(1)-C(21)-N(4)
P(2)-C(11)-N(2)
91.13(11)
166.85(11)
100.45(5)
157.04(5)
96.02(5)
88.62(5)
87.15(5)
100.8(3)
113.9(4)
Ru(11)-N(101)
Ru(11)-P(101)
Ru(11)-Cl(11)
2.138(4)
2.291(1)
2.459(1)
Ru(11)-P(102)
Ru(11)-P(103)
Ru(11)-Cl(12)
2.271(1)
2.313(1)
2.470(1)
P-C 1.825(5)-1.846(5)
N(101)-Ru(11)-P(101)
N(101)-Ru(11)-P(103)
P(101)-Ru(11)-P(103)
N(101)-Ru(11)-Cl(11)
P(101)-Ru(11)-Cl(11)
N(101)-Ru(11)-Cl(12)
P(101)-Ru(11)-Cl(12)
Cl(11)-Ru(11)-Cl(12)
P(102)-C(111)-N(102)
P(101)-C(121)-N(104)
87.80(12)
168.30(11)
99.49(5)
89.36(11)
94.66(5)
82.92(11)
170.04(5)
88.88(5)
113.6(4)
116.8(4)
P(102)-Ru(11)-P(101)
P(102)-Ru(11)-P(103)
N(101)-Ru(11)-P(102)
P(102)-Ru(11)-Cl(11)
P(103)-Ru(11)-Cl(11)
P(102)-Ru(11)-Cl(12)
P(103)-Ru(11)-Cl(12)
P(102)-C(106)-N(101)
P(101)-C(116)-N(103)
84.40(5)
102.71(5)
68.71(11)
158.06(5)
99.07(5)
88.84(5)
89.11(5)
100.9(3)
111.5(3)
Table 8. Selected Bond Lengths (Å) and Angles (deg) for 12 with
Estimated Standard Deviations in Parentheses
Ru(1)-Cl(1)
Ru(1)-P(1)
Ru(1)-P(3)
2.460(1)
2.314(1)
2.348(1)
Ru(1)-Cl(2)
Ru(1)-P(2)
Ru(1)-N(1)
2.430(1)
2.316(1)
2.146(3)
P-C 1.826(4)-1.854(5)
Cl(1)-Ru(1)-Cl(2) 85.65(4)
Cl(1)-Ru(1)-P(2) 91.36(4)
Cl(1)-Ru(1)-N(1) 81.2(1)
Cl(2)-Ru(1)-P(2) 93.41(4)
Cl(2)-Ru(1)-N(1) 90.9(1)
Cl(1)-Ru(1)-P(1) 168.18(4)
Cl(1)-Ru(1)-P(3) 85.84(5)
Cl(2)-Ru(1)-P(1) 84.48(5)
Cl(2)-Ru(1)-P(3) 158.30(4)
P(1)-Ru(1)-P(2)
95.71(5)
92.4(1)
P(1)-Ru(1)-P(3)
P(2)-Ru(1)-P(3)
P(3)-Ru(1)-N(1)
Ru(1)-P(1)-C(5)
C(1)-P(1)-C(5)
C(5)-P(1)-C(11)
101.11(5) P(1)-Ru(1)-N(1)
106.71(4) P(2)-Ru(1)-N(1)
171.1(1)
117.5(2)
68.0(1)
Ru(1)-P(1)-C(1)
107.9(2)
101.1(2)
101.7(2)
Ru(1)-P(1)-C(11) 125.9(2)
C(1)-P(1)-C(11)
Ru(1)-P(2)-C(4)
99.2(2)
118.4(1)
Ru(1)-P(2)-C(17) 113.5(2)
Ru(1)-P(2)-C(23) 119.4(1)
C(4)-P(2)-C(17) 101.2(2)
C(4)-P(2)-C(23)
102.0(2)
C(17)-P(2)-C(23) 99.2(2)
Ru(1)-P(3)-C(34) 129.4(2)
C(29)-P(3)-C(34) 105.1(2)
C(34)-P(3)-C(40) 97.9(2)
Ru(1)-P(3)-C(29) 83.6(2)
Ru(1)-P(3)-C(40) 128.2(2)
C(29)-P(3)-C(40) 105.6(2)
Figure 7. ORTEP representation of cis-RuCl
2
2
(dppb)(P,N-PPh (py))
(12). Thermal ellipsoids for non-hydrogen atoms are drawn at 50%
P(3)-C(29)-N(1)
103.0(3)
probability. Some of the phenyl carbon atoms have been omitted for
clarity.
MeOH (10 mL) with 0.77 mM Ru complex and 0.153 M imine
2
4,29
substrate).
The conversions of PhC(H)dNPh to PhCH2N-
(
(
py) P atom. The structure is comparable to those of cis-RuCl2-
dppb)(N-N) (N-N ) 2,2′-bipyridine or o-phenanthroline) that
(H)Ph under these conditions after 3 h were 80, 99, and 63%
for the chloro, bromo, and iodo complexes, respectively. For
comparison, under the same conditions, the dinuclear species
contain the “less compressed” five-membered chelate rings with
N-Ru-N angles of 76.7 and 78.2°, respectively.34
[RuX(dppb)]2(µ-X)2 catalyzed the hydrogenation of PhC(H)d
Preliminary Catalysis Results. Preliminary results show that
the complexes fac-RuX2(P,P,N-d(py)pcp)(PPh3) (X ) Cl, Br,
I; 7b, 8, and 9, respectively) can effect the homogeneous
catalytic hydrogenation of imines to amines. The experiments
were performed under conditions employed previously in this
NPh with conversions of 24 (X ) Cl), 74 (X ) Br), and 100%
2
9
(X ) I). The hydrogenation of a second imine substrate PhC-
(H)dNCH2Ph was also investigated using 7b, 8, and 9 as
precursor catalysts. Under the same conditions outlined above,
but for 1 h reaction time, the conversions to dibenzylamine were
5 (X ) Cl), 10 (X ) Br), and 28% (X ) I) while [RuCl(dppb)]2-
II
laboratory to allow for comparison with data obtained with “Ru -
(
P-P)” catalytic precursors (using 1000 psi of H2, at r.t. in
(
µ-Cl)2 was much more active, giving 87% conversion.29
(
34) Quieroz, S. J.; Batista, A. A.; Oliva, G.; do P. Gambardella, M. T.;
Santos, R. H. A.; MacFarlane, K. S.; Rettig, S. J.; James, B. R. Inorg.
Chim. Acta 1998, 267, 209.
Although the catalytic results are preliminary, they illustrate
again the important role that the halogen plays in imine

3966 Inorganic Chemistry, Vol. 38, No. 18, 1999
Jones et al.
hydrogenations,29,35 and that the comparison of reactivity
between complexes may be substrate dependent. The RuCl2-
incorporating a P,N-chelate ring, where there is also some
evidence for lability of the N atom. The Ru-d(py)pcp complexes
are effective precursors for catalytic H2 hydrogenation of
aldimines in MeOH solution. The related ligand d(py)pe, the
2-pyridyl analogue of the well-known diphos, has been shown
to exhibit P,P bonding at Pt(II). Of special interest, but not
described here, d(py)pe and several of the complexes have some
solubility in water, and are freely soluble in dilute aqueous acid
solution. The aqueous solution chemistry of these pyridyl-
diphosphine systems, and their potential for homogeneous
catalysis in aqueous media, are currently being studied.
(d(py)pcp)(PPh3) complex in the solid state and in benzene
contains a P3N donor ligand set, while in CDCl3 there is NMR
evidence for some lability of the N atom; whether such behavior
is involved in the catalysis in MeOH is as yet unknown, but
the catalytic activity is good, and further studies, particularly
at making hydrido derivatives, are at hand. The facile syntheses
and air-stability of the RuX2(d(py)pcp)(PPh3) complexes make
them attractive as catalyst precursors. Resolution of the chiral
d(py)pcp would allow investigation into catalytic asymmetric
hydrogenation. Of note, Noyori’s group group has used a
tetradentate, diphosphine/diamine P2N2 donor set (which con-
tains chirality at methine C atoms of a cyclohexane ring that
bridges the N atoms) within a trans-RuCl2(P2N2) complex that
catalyzes effective transfer hydrogenations of imines (from
Acknowledgment. We thank the Natural Sciences and
Engineering Research Council of Canada for financial support,
Johnson Matthey Ltd. and Colonial Metals Inc. for the loans of
RuCl3‚xH2O and K2[PtCl4], the Royal Society for the award of
a fellowship to M.B.S., and Dr. V. G. Young, Jr. (X-ray
Crystallographic Laboratory, University of Minneapolis) for
determination of the structures of 7a and 7b.
-propanol).36
2
Conclusions
Supporting Information Available: Tables of atomic coordinates
and equivalent isotropic thermal parameters, hydrogen atom parameters,
anisotropic thermal parameters, complete lists of bond lengths and
angles, and torsion angles for the structures of d(py)pe, 2, 3, 7a, 7b,
and 12. This material is available free of charge via the Internet at
http://pubs.acs.org.
A new 2-pyridyldiphosphine ligand, d(py)pcp, has been
synthesized as a racemate and its coordination at Pt(II) and Ru-
(II) centers investigated. The P,P- and P,P,N-bonding modes
are found at the Pt(II) and Ru(II) centers, respectively, the latter
(35) James, B. R. Catal. Today 1997, 37, 209.
(36) Noyori, R.; Hashiguchi, S. Acc. Chem. Res. 1997, 30, 97.
IC990002O