Fig. 3 Structural representations of (a) [SiNP2]FeCl (3) and (b) [SiNP2]CoI (4b) with thermal ellipsoids at 50% probability, and (c) a space-filling
Si
˚
representation of [ NP2]FeCl. (a) Hydrogen atoms and a molecule of benzene have been omitted for clarity. Selected bond distances (A) and angles (u): Fe–
N 1.953(2), Fe–P1 2.4180(8), Fe–P2 2.4903(8), Fe–Cl 2.2418(8), N–Fe–P1 89.76(5), N–Fe–P2 90.91(6), N–Fe–Cl 140.03(6), P1–Fe–P2 94.98(3), P1–Fe–Cl
˚
118.30(3), P2–Fe–Cl 112.48(3). (b) Hydrogen atoms and a molecule of diethyl ether have been omitted for clarity. Selected bond distances (A) and angles
(u): Co–N 1.910(3), Co–P1 2.3849(9), Co–P2 2.3731(8), Co–I 2.5258(5), N–Co–P1 89.78(8), N–Co–P2 90.29(9), N–Co–I 143.57(8), P1–Co–P2 93.44(3), P1–
Co–I 115.61(3), P2–Co–I 112.33(3).
(Rint 5 7.69%) with I . 2s(I); 4b, C43H54CoINOP2Si: monoclinic, space
+ 0.24 V. A smaller reduction wave centered at 20.63 V grows in
˚
˚
˚
group P21/c, a 5 11.6071(8) A, b 5 21.6762(15) A, c 5 16.8895(12) A,
as a result of scanning through the oxidation process at + 0.24 V.
The CV data for 4a show a quasi-reversible wave centered at
b 5 92.988(2)u, V 5 4243.6(5) A , Z 5 4, m(Mo-Ka) 5 1.268 mm21. 77696
3
˚
total reflections, 14707 independent (Rint 5 7.91%) with I . 2s(I). CCDC
289249–289252. For crystallographic data in CIF or other electronic
format see DOI: 10.1039/b516046d
/
20.17 V, corresponding to a CoIII II oxidation event. Additionally,
there is an irreversible reduction wave at 21.4 V and a smaller
/
irreversible oxidative wave at 20.40 V. The putative CoII I
1 T. A. Betley and J. C. Peters, J. Am. Chem. Soc., 2004, 126, 6252;
S. D. Brown, T. A. Betley and J. C. Peters, J. Am. Chem. Soc., 2003,
125, 322; D. M. Jenkins, T. A. Betley and J. C. Peters, J. Am. Chem.
Soc., 2002, 124, 11238.
2 D. M. Jenkins, A. J. Di Bilio, M. J. Allen, T. A. Betley and J. C. Peters,
J. Am. Chem. Soc., 2002, 124, 15336; D. M. Jenkins and J. C. Peters,
J. Am. Chem. Soc., 2005, 127, 7148.
3 D. M. Jenkins and J. C. Peters, J. Am. Chem. Soc., 2003, 125, 11162.
4 M. D. Fryzuk and P. A. Macneil, J. Am. Chem. Soc., 1981, 103, 3592.
5 M. D. Fryzuk, J. B. Love and S. J. Rettig, Chem. Commun., 1996, 2783;
M. D. Fryzuk, S. A. Johnson and S. J. Rettig, J. Am. Chem. Soc., 1998,
120, 11024.
6 M. D. Fryzuk, Can. J. Chem., 1992, 70, 2839; M. D. Fryzuk, J. B. Love,
S. J. Rettig and V. G. Young, Science, 1997, 275, 1445.
7 M. D. Fryzuk, D. B. Leznoff, E. S. F. Ma, S. J. Rettig and V. G. Young,
Organometallics, 1998, 17, 2313; M. D. Fryzuk, D. B. Leznoff,
R. C. Thompson and S. J. Rettig, J. Am. Chem. Soc., 1998, 120, 10126.
8 M. Ingleson, H. Fan, M. Pink, J. Tomaszewski and K. G. Caulton,
J. Am. Chem. Soc., 2006, 128, 1804.
reduction event occurs at a potential ca. 0.7 V more positive for
compound 4a compared with 2a.
In summary, we have introduced two new amido-polypho-
sphine ligands and thoroughly characterized divalent iron and
cobalt halide complexes of each system. The [SiNP3] and [SiNP2]
ligands are related in that each is monoanionic and strongly
electron-releasing. However, whereas the [SiNP2] ligand is predis-
posed to bind in a tridentate, tripodal fashion, the [SiNP3] ligand
can adopt both tridentate and tetradentate binding modes
depending on the electronic requirements of the metal center.
The [SiNP2] ligand enforces a highly distorted geometry reminis-
cent of other tripodal ligands such as [Tp] and [PhBP3]. We are
currently exploring the affinity of these systems for binding N2 and
other p-acidic substrates under reducing conditions.
We acknowledge the NIH (GM 070757 to JCP) for financial
support of this work. MTW is grateful to the Moore Foundation
for a graduate fellowship. Neal Mankad and Larry Henling
provided crystallographic assistance.
9 O. V. Ozerov, C. Y. Guo, V. A. Papkov and B. M. Foxman, J. Am.
Chem. Soc., 2004, 126, 4792; A. Walstrom, M. Pink, X. F. Yang,
J. Tomaszewski, M. H. Baik and K. G. Caulton, J. Am. Chem. Soc.,
2005, 127, 5330.
10 P. Stoppioni, F. Mani and L. Sacconi, Inorg. Chim. Acta, 1974, 11, 227;
T. A. George, D. J. Rose, Y. D. Chang, Q. Chen and J. Zubieta, Inorg.
Chem., 1995, 34, 1295.
Notes and references
11 D. F. Evans, J. Chem. Soc., 1959, 2003; S. K. Sur, J. Magn. Reson.,
1989, 82, 169.
{ Details of the X-ray diffraction studies: 1, C56.5H61ClFeNP3Si: triclinic,
˚
space group P-1, a 5 10.8604(17) A, b 5 20.831(3) A, c 5 23.586(4) A,
˚
˚
12 Although [SiNP3]CoI (2b) was more readily crystallized than its chloride
congener 2a, analytically pure bulk samples of 2a were more readily
obtained.
3
˚
a 5 72.318(3)u, b 5 83.313(3)u, c 5 89.880(3)u, V 5 5046.3(14) A , Z 5 4,
m(Mo-Ka) 5 0.509 mm21. 19505 total reflections, 14316 independent
(Rint 5 8.01%) with I . 2s(I); 2a, C51H52ClCoNP3Si: triclinic, space group
˚
˚
˚
13 For a similar approach to enforcing a fac-only geometry, cf. the
diamido-pyridyl ligands developed by Gade; L. H. Gade, Chem.
Commun., 2000, 173; P. Mehrkhodavandi, P. J. Bonitatebus and
R. R. Schrock, J. Am. Chem. Soc., 2000, 122, 7841.
14 S. Trofimenko, Scorpionates: the coordination chemistry of polypyrazolyl
borates, Imperial College Press: London, 1999.
P-1, a 5 12.8058(15) A, b 5 17.612(2) A, c 5 20.505(3) A, a 5 93.701(4)u,
3
˚
b 5 91.736(4)u, c 5 103.463(4)u, V 5 4483.4(10) A , Z 5 4, m(Mo-
Ka)
5
0.613 mm21
(Rint 5 13.19%) with I . 2s(I); 2b, C63H64CoINP3Si: monoclinic, space
.
17435 total reflections, 9939 independent
˚
˚
˚
group P21/c, a 5 13.0701(10) A, b 5 19.1387(15) A, c 5 22.1493(16) A,
21
b 5 102.943(3)u, V 5 5399.8(7) A , Z 5 4, m(Mo-Ka) 5 1.042 mm
3
˚
.
15 P. J. Schebler, B. S. Mandimutsira, C. G. Riordan, L. M. Liable-Sands,
C. D. Incarvito and A. L. Rheingold, J. Am. Chem. Soc., 2001, 123, 331;
P. H. Ge, B. S. Haggerty, A. L. Rheingold and C. G. Riordan, J. Am.
Chem. Soc., 1994, 116, 8406.
44992 total reflections, 10823 independent (Rint 5 16.66%) with I . 2s(I);
˚
3, C45H50ClFeNP2Si: monoclinic, space group P21/n, a 5 9.793(3) A,
3
˚
˚
˚
b 5 9.371(3) A, c 5 44.610(12) A, b 5 94.581(4)u, V 5 4080.9(19) A , Z 5 4,
m(Mo-Ka) 5 0.575 mm21. 34419 total reflections, 8553 independent
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