Ligand design for the assembly of polynuclear complexes: Syntheses and structures of trinuclear and tetranuclear aluminum alkyl complexes bearing tripodal diamidoselenophosphinito ligands and a comparison to related tripodal triamidophosphine complexes

Article abstract of DOI:10.1021/om0607447

Reactions of the triaminophosphines P(CH₂NHAr^R) ₃ (1a-c, where Ar^R = 3,5-(CF₃) ₂C₆H₃ for a; Ar^R = Ph for b, Ar ^R = 3,5-Me₂C₆H₃ for c) with selenium afford the triaminophosphine selenides Se=P(CH₂-NHAr ^R)₃ (2a-c). The phosphine selenides 2a-c react with 4 equiv of AlMe₃ at room temperature to generate the triangular trinuclear aluminum complexes [P(CH₂NAr^R) ₂Se](AlMe₂)₃ (3a-c). The byproduct of the formation of 3a was hydrolyzed and provided CH₃CH₂N(H)-3, 5-(CF₃)₂C₆H₃. When 2a-c are treated with excess AlMe₃, the corresponding tetranuclear Lewis acid-base adducts Me₃Al·[P(CH₂NAr^R) ₂Se]-(AlMe₂)₃ (4b,c) are isolated. The reaction of P(CH₂NHAr^R)₃ (1a-c) with 2 equiv of AlMe₃ produces the dinuclear aluminum complexes P(CH ₂NAr^R)₃Al₂Me₃ (5a-c). When 1b,c are reacted with excess AlMe₃, the Lewis acid-base adducts Me₃Al·P(CH₂NAr^R)₃Al ₂Me₃ (6b,c) are isolated. Solid-state molecular structures were determined for complexes 2a, 2b, 2c, 3a, 3c, 4b, 5a, and 6b by X-ray crystallography.

Full text of DOI:10.1021/om0607447

5594
Organometallics 2006, 25, 5594-5602
Ligand Design for the Assembly of Polynuclear Complexes:
Syntheses and Structures of Trinuclear and Tetranuclear Aluminum
Alkyl Complexes Bearing Tripodal Diamidoselenophosphinito
Ligands and a Comparison to Related Tripodal Triamidophosphine
Complexes
Hua Han and Samuel A. Johnson*
Department of Chemistry and Biochemistry, UniVersity of Windsor, Windsor, Ontario, Canada, N9B 3P4
ReceiVed August 16, 2006
Reactions of the triaminophosphines P(CH2NHArR)3 (1a-c, where ArR ) 3,5-(CF3)2C6H3 for a; ArR
) Ph for b, ArR ) 3,5-Me2C6H3 for c) with selenium afford the triaminophosphine selenides SedP(CH2-
NHArR)3 (2a-c). The phosphine selenides 2a-c react with 4 equiv of AlMe3 at room temperature to
generate the triangular trinuclear aluminum complexes [P(CH2NArR)2Se](AlMe2)3 (3a-c). The byproduct
of the formation of 3a was hydrolyzed and provided CH3CH2N(H)-3,5-(CF3)2C6H3. When 2a-c are treated
with excess AlMe3, the corresponding tetranuclear Lewis acid-base adducts Me3Al‚[P(CH2NArR)2Se]-
(AlMe2)3 (4b,c) are isolated. The reaction of P(CH2NHArR)3 (1a-c) with 2 equiv of AlMe3 produces the
dinuclear aluminum complexes P(CH2NArR)3Al2Me3 (5a-c). When 1b,c are reacted with excess AlMe3,
the Lewis acid-base adducts Me3Al‚P(CH2NArR)3Al2Me3 (6b,c) are isolated. Solid-state molecular
structures were determined for complexes 2a, 2b, 2c, 3a, 3c, 4b, 5a, and 6b by X-ray crystallography.
triangular trimetallic Mn(II) complexes are readily assembled
using these ligands, along with their isostructural diamagnetic
Mg(II) analogues;8 however, when used with trivalent or higher
oxidation state metal centers with three labile ligand sites, these
ligands have a tendency to chelate all three amido donors to a
single metal,7 which does not allow for the assembly of
complexes with multiple adjacent metal centers. This is shown
as complex A in Figure 1.
The factors that led us to investigate selenium donors in
polydentate ligand designs that favor polynuclear complex
formation were both the increased polarizability of the heavier
chalcogenides, which should encourage electronic communica-
tion between metal centres, and their propensity to bridge metal
centers. In this article we report the synthesis of diamidosele-
nophosphinito ancillary ligands, which favor the formation of
triangular complexes with aluminum, shown in Figure 1 as
complex B. Anionic Se donors are much less common than their
oxygen and sulfur analogues,9 and selenophosphinito donors
(R2PSe-) have not previously been incorporated into multiden-
tate donor ligands, to the best of our knowledge, although related
ligands are known.10-12
Introduction
Triangular complexes are of current interest for both their
potential in new stoichiometric and catalytic transformations,
due to the ability of adjacent transition metals to cooperatively1
activate substrates,2 and their physical properities, which include
luminescence3 and magnetic spin-frustration.4 A plethora of
ligands are known to bridge metals and promote cluster
formation;5 however, multidentate ancillary ligands that can
assemble triangular complexes that contain adjacent metal
centers bearing functionalizable sites with an array of different
metals are uncommon. Our studies have utilized the trianionic
triamidophosphine donors P(CH2NArR)3, where ArR represents
an aryl substituent as an ancillary ligand for polynuclear complex
assembly. Unlike other triamido and amidophosphine ligands,
the P(CH2NArR)3 ligands cannot chelate all four of their donor
atoms to a single metal.6,7 We have recently shown how
* To whom correspondence should be addressed. E-mail: sjohnson@
uwindsor.ca. Fax: (519) 973-7098.
(1) Bosnich, B. Inorg. Chem. 1999, 38, 2554-2562.
(2) Suzuki, H. Eur. J. Inorg. Chem. 2002, 1009-1023.
(3) Fung, E. Y.; Olmstead, M. M.; Vickery, J. C.; Balch, A. L. Coord.
Chem. ReV. 1998, 171, 151-159.
The similar ionic radius of Al(III) to the radii of the trivalent
first-row transition metals and its diamagnetic nature make it a
(4) (a) Cannon, R. D.; White, R. P. Prog. Inorg. Chem. 1988, 36, 195-
298. (b) Cage, B.; Cotton, F. A.; Dalal, N. S.; Hillard, E. A.; Rakvin, B.;
Ramsey, C. M. J. Am. Chem. Soc. 2003, 125, 5270-5271. (c) Berry, J. F.;
Cotton, F. A.; Liu, C. Y.; Lu, T.; Murillo, C. A.; Tsukerblat, B. S.; Villagran,
D.; Wang, X. J. Am. Chem. Soc. 2005, 127, 4895-4902. (d) Yoon, J.;
Mirica, L. M.; Stack, T. D. P.; Solomon, E. I. J. Am. Chem. Soc. 2004,
126, 12586-12595. (e) Telfer, S. G.; Kuroda, R.; Lefebvre, J.; Leznoff, D.
B. Inorg. Chem. 2006, 45, 4592-4601.
(8) Hatnean, J. A.; Raturi, R.; Lefebvre, J.; Leznoff, D. B.; Lawes, G.;
Johnson, S. A. J. Am. Chem. Soc, in press.
(9) Arnold, J. Prog. Inorg. Chem. 1995, 43, 353-417.
(10) Walther, B. Coord. Chem. ReV. 1984, 60, 67-105.
(11) (a) Chivers, T.; Parvez, M.; Seay, M. A. Inorg. Chem. 1994, 33,
2147-2150. (b) Chivers, T.; Krahn, M.; Schatte, G.; Parvez, M. Inorg.
Chem. 2003, 42, 3994-4005. (c) Bochmann, M.; Bwembya, G. C.; Whilton,
N.; Song, X.; Hursthouse, M. B.; Coles, S. J.; Karaulov, A. J. Chem. Soc.,
Dalton Trans. 1995, 1887-1892. (d) Haiduc, I. J. Organomet. Chem. 2001,
623, 29-42.
(5) (a) Swavey, S.; Brewer, K. J. Compr. Coord. Chem. II 2004, 1, 135-
157. (b) Dyson, P. J. Coord. Chem. ReV. 2004, 248, 2443-2458. (c)
Winpenny, R. E. P. Compr. Coord. Chem. II 2004, 7, 125-175. (d) Chivers,
T. Can. J. Chem. 2001, 79, 1841-1850.
(6) Keen, A. L.; Doster, M.; Han, H.; Johnson, S. A. Chem. Commun.
2006, 1221-1223.
(7) Han, H.; Elsmaili, M.; Johnson, S. A. Inorg. Chem. 2006, 45, 7435-
7445.
(12) (a) Lief, G. R.; Carrow, C. J.; Stahl, L.; Staples, R. J. Organome-
tallics 2001, 20, 1629-1635. (b) Briand, G. G.; Chivers, T.; Krahn, M.;
Parvez, M. Inorg. Chem. 2002, 41, 6808-6815.
10.1021/om0607447 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 10/18/2006

Assembly of Polynuclear Complexes
Organometallics, Vol. 25, No. 23, 2006 5595
Figure 1. Potential bonding modes of the formally trianionic
ligands P[CH2NArR]3 and Se-P[CH2NArR]2 with metal complexes
labeled M.
convenient starting point for the study of this new ancillary
ligand. Numerous amidophosphine13,14 as well as monoden-
tate,15-17 bidentate,18-20 tridentate,21 and tripodal22 amido
complexes of aluminum are known. These complexes have been
studied largely as potential precursors for materials applica-
tions,23 as well as to emulate the olefin polymerizations observed
with related amidinate ligands.24
Figure 2. ORTEP depiction of the solid-state molecular structure
of 2c as determined by X-ray crystallography. Ellipsoids are drawn
at the 50% probability level, and hydrogen atoms are omitted for
clarity.
Results and Discussion
Oxidation of P(CH2NHArR)3 with Selenium. Treatment of
the previously reported7 triamidophosphines P(CH2NHArR)3,
1a-c (where ArR ) 3,5-(CF3)2C6H3, Ph, and 3,5-Me2C6H3 for
a, b, and c, respectively), with excess elemental selenium in
toluene afforded the phosphine selenides SeP(CH2NHArR)3, as
shown in eq 1. These white solids were isolated in yields ranging
from 80 to 87% and are neither air- nor moisture-sensitive.
parameters are provided in Table 1. The C(1)-P(1)-C(2),
C(1)-P(1)-C(3), and C(2)-P(1)-C(3) angles for the free
ligand precursor 2c are 105.84(13)°, 105.56(11)°, and 108.39-
(11)°, respectively, which are comparable to the tetrahedral angle
of 109.5°. Comparison of the structure of phosphine selenide
2a with that of the parent phosphine ligand 1a7 reveals that the
average P-C bond length of 2a is shorter by 0.017 Å, and the
sum of C-P-C bond angles is wider by about 13.3° (312.85-
(23)° for 2a, 299.51(20)° for 1a7). These differences correlate
with the larger covalent radii of P(III) compared to P(V), as
well as the larger repulsion of the lone pair of P(III) versus the
PdSe bond. In 2a-c, the P-Se bond lengths are 2.0973(12),
2.1026(12), and 2.0960(7) Å, respectively, which are similar
to those observed in the selenides of substituted arylphos-
phines.25 The 31P{1H} NMR spectra display singlets at δ 42.6,
46.3, and 44.5 and selenium satellites (77Se, I ) 1/2, 7.6%) with
1JSeP values of 742.8, 719.7, and 716.1 Hz for 2a-c, respec-
tively. These values are within the range expected for R3PdSe
functional groups.26,27 The magnitude of 1JSeP has been used to
characterize the lone-pair s-orbital character of phosphine donors
Colorless crystals of 2a-c suitable for X-ray diffraction were
grown by slow evaporation of solutions of equal amounts of
ethanol and acetone. The solid-state molecular structure of 2c
is shown in Figure 2, and cell constants and refinement
(13) (a) Lee, W.-Y.; Liang, L.-C. J. Chem. Soc., Dalton Trans. 2005,
1952-1956. (b) Fryzuk, M. D.; Giesbrecht, G. R.; Olovsson, G.; Rettig, S.
J. Organometallics 1996, 15, 4832-4841.
(14) Liang, L.-C.; Huang, M.-H.; Hung, C.-H. Inorg. Chem. 2004, 43,
2166-2174.
(15) (a) Passarelli, V.; Carta, G.; Rossetto, G.; Zanella, P. J. Chem. Soc.,
Dalton Trans. 2003, 1284-1291. (b) Jancik, V.; Pineda, L. W.; Pinkas, J.;
Roesky, H. W.; Neculai, D.; Neculai, A. M.; Herbst-Irmer, R. Angew. Chem.,
Int. Ed. 2004, 43, 2142-2145.
(16) Dillingham, M. D. B.; Hill, J. B.; Lee, B.; Schauer, S. J.; Pennington,
W. T.; Robinson, G. H.; Hrncir, D. C. J. Coord. Chem. 1993, 28, 337-
346.
(17) (a) Waggoner, K. M.; Power, P. P. J. Am. Chem. Soc. 1991, 113,
3385-3393. (b) Eisler, D. J.; Chivers, T. Can. J. Chem. 2006, 84, 443-
452. (c) Brask, J. K.; Chivers, T.; Yap, G. P. A. Chem. Commun. 1998,
2543-2544.
(18) Hlavinka, M. L.; Hagadorn, J. R. Chem. Commun. 2003, 2686-
2687.
(19) Bezombes, J.-P.; Gehrhus, B.; Hitchcock, P. B.; Lappert, M. F.;
Merle, P. G. J. Chem. Soc., Dalton Trans. 2003, 1821-1829.
(20) (a) Gardinier, J. R.; Gabbai, F. P. New J. Chem. 2001, 25, 1567-
1571. (b) Jiang, Z.; Interrante, L. V.; Kwon, D.; Tham, F. S.; Kullnig, R.
Inorg. Chem. 1991, 30, 995-1000. (c) Hitchcock, P. B.; Lappert, M. F.;
Merle, P. G. Phosphorus Sulfur Silicon Relat. Elem. 2001, 168-169, 363-
366.
(21) Gibson, V. C.; Nienhuis, D.; Redshaw, C.; White, A. J. P.; Williams,
D. J. J. Chem. Soc., Dalton Trans. 2004, 1761-1765.
(22) Pinkas, J.; Wang, T.; Jacobson, R. A.; Verkade, J. G. Inorg. Chem.
1994, 33, 5244-5253.
(23) Sauls, F. C.; Interrante, L. V. Coord. Chem. ReV. 1993, 128, 193-
207.
1
and, thus, their σ-donor ability.28 A larger value of JSeP
corresponds to greater s-orbital character of the phosphorus lone
pair and a weaker electron-donor ability of the phosphine
ligand.29 The donor abilities of the phosphines in precursors
1a-c are affected by the nature of the aryl substituents, with
the most electron-withdrawing aryl group providing the phos-
1
phine selenide with the largest JSeP value, 743.7 Hz. In
1
comparison, SedPPh3 has a JSeP value of 733 Hz,28,30 which
predicts that 1a-c should have donor properties similar to
triphenylphosphine. A similar conclusion regarding the donor
ability of 1a-c was reached via a study of the CO stretching
frequencies31 of the complexes trans-Rh(CO)Cl[P(CH2NHArR)3]2,
as previously reported.7
(25) (a) Howell, J. A. S.; Fey, N.; Lovatt, J. D.; Yates, P. C.; McArdle,
P.; Cunningham, D.; Sadeh, E.; Gottlieb, H. E.; Goldschmidt, Z.; Hursthouse,
M. B.; Light, M. E. J. Chem. Soc., Dalton Trans. 1999, 3015-3028. (b)
Steinberger, H. U.; Ziemer, B.; Meisel, M. Acta Crystallogr. Sect. C 2001,
57, 323-324.
(26) Barron, A. R. J. Chem. Soc., Dalton Trans. 1988, 3047-3050.
(27) Slawin, A. M. Z.; Wheatley, J.; Wheatley, M. V.; Woollins, J. D.
Polyhedron 2003, 22, 1397-1405.
(28) Allen, D. W.; Taylor, B. F. J. Chem. Soc., Dalton Trans. 1982,
51-54.
(29) Andersen, N. G.; Keay, B. A. Chem. ReV. 2001, 101, 997-1030.
(30) Allen, D. W.; Nowell, I. W.; Taylor, B. F. J. Chem. Soc., Dalton
Trans. 1985, 2505-2508.
(24) Coles, M. P.; Jordan, R. F. J. Am. Chem. Soc. 1997, 119, 8125-
8126.

5596 Organometallics, Vol. 25, No. 23, 2006
Table 1. Crystallographic Data for Compounds 2a-c, 3a, 3c, 4b, 5a, and 6b
Han and Johnson
2a
2b
2c
3a
empirical formula
fw
C27H18F18N3PSe
836.4
C21H24N3PSe
428.37
C27H36N3PSe
512.53
C24H28Al3F12N2PSe
763.35
cryst syst
a (Å)
b (Å)
triclinic
14.832(2)
15.494(2)
16.371(3)
73.943(2)
65.716(2)
81.208(2).
3292.3(9)
P1h
triclinic
10.025(3)
10.598(3)
10.605(3)
65.584(3)
86.104(3)
75.794(3)
993.9(5)
P1h
monoclinic
8.1088(7)
11.4874(10)
28.225(3)
90.0
94.317(2)
90.0
2621.6(4)
P2(1)/n
4
triclinic
9.0018(16)
13.892(3)
13.947(3)
68.850(2)
85.035(2)
88.038(2)
1620.5(5)
P1h
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z value
4
1
2
D
calc (g/cm3)
1.766
1.320
173
55.0
1.431
1.979
173
50.0
1.299
1.512
173
55.0
1.564
1.377
173
50.0
µ(Mo KR) (mm-1
temperature (K)
2θmax (deg)
)
total no. of reflns
37705
11128
20415
18272
no. of unique reflns; Rint
transmn factors
no. with I g 2σ(I)
no. of variables
14633; 0.072
0.89-0.91
8432
4393; 0.063
0.89-0.96
3497
4607; 0.034
0.89-0.99
3772
7194; 0.022
0.89-0.96
6346
988
247
307
412
no. of reflns/params
R; wR2 (all data)
GOF
15.14
0.121, 0.151
1.000
17.78
0.077; 0.126
1.101
15.04
0.049; 0.112
1.028
17.46
0.042; 0.101
1.063
residual density (e-/Å3)
0.721, -0.503
0.952, -0.492
0.570, -0.327
0.915, -0.507
3c
4b
5a
6b
empirical formula
fw
C24H40Al3N2PSe
547.47
C23H41Al4N2PSe
563.44
C30H24Al2F18N3P
853.44
C27H39Al3N3P
517.54
cryst syst
a (Å)
b (Å)
monoclinic
13.118(2)
8.3825(14)
28.507(5)
90.0
90.187(2)
90.0
3134.7(9)
P2(1)/n
4
orthorhombic
15.679(3)
10.954(2)
8.5522(16)
90.0
90.0
90.0
1468.8(5)
Pmn2(1)
2
triclinic
11.2709(15)
11.6947(15)
15.652(2)
68.4510(10)
86.0640(10)
78.9210(10)
1883.1(4)
P1h
orthorhombic
11.8225(13)
14.7615(16)
33.447(4)
90.0
90.0
90.0
5837.1(11)
Pbca
8
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z value
2
D
calc (g/cm3)
1.256
1.351
173
55.0
1.274
1.466
173
55.0
1.574
0.239
173
50.0
1.178
0.204
173
55.0
µ(Mo KR) (mm-1
temperature (K)
2θmax (deg)
)
total no. of reflns
34 149
10 182
18 227
62 133
no. of unique reflns; Rint
transmn factors
no. with I g2σ(I)
no. of variables
7097; 0.038
0.89-0.99
5973
3390; 0.052
0.89-0.91
2761
6628; 0.024
0.89-0.99
5625
6679; 0.043
0.89-0.96
5618
311
151
527
313
no. of reflns/params
R; wR2 (all data)
GOF
22.82
0.049; 0.115
1.133
22.45
0.064; 0.096
1.063
12.58
0.068; 0.175
1.034
21.34
0.055; 0.119
1.112
residual density (e-/Å3)
0.852, -0.596
1.002, -0.398
0.750, -0.520
0.389, -0.241
Trinuclear Complexes via Reactions of SedP(CH2NHArR)3
with AlMe3. The phosphine selenides SedP(CH2NHArR)3 (2a-
c) react with 4 equiv of AlMe3 in toluene at room temperature
to give [P(CH2NArR)2Se](AlMe2)3 (3a-c), as shown in Scheme
1. The reactions proceed over the course of 24 h, with the
putative and unisolable amine-trimethylaluminum adducts as the
much more soluble in pentane than the scarcely soluble 3a-c
and were easily rinsed from the crude product mixtures without
significant loss of yield. The 1H NMR spectra of these
byproducts are complicated and exhibit a variety of triplet and
quartet resonances, as would be expected for ethyl substituents
bound to nitrogen. The byproducts are believed to be dimers of
the type [CH3CH2N(ArR)AlMe2]2, and their complex 1H NMR
spectra are likely due to the presence of cis and trans isomers
and perhaps also larger oligomers.16,32,35 Additional insight
regarding the nature of the byproduct was obtained by the hydrol-
ysis of the pentane fraction used to rinse the crude product mix-
ture in the synthesis of 3a. The hydrolysis product was identified
as CH3CH2N(H)-3,5-(CF3)2C6H3 by 1H and 13C{1H} NMR
spectroscopy. The exact mechanism by which the ligand arm
1
only intermediates observable by H NMR spectroscopy; the
observation of such adducts is not uncommon.19,32 The use of
4 equiv of AlMe3 was necessary because the overall reaction
involves the loss of one ligand -CH2NHArR arm. This is a new
synthetic route to selenophosphinito ligands, which are poorly
studied and more commonly prepared by the insertion of 1 equiv
of Se into a metal-phosphido bond.33,34 The byproducts are
(31) Tolman, C. A. J. Am. Chem. Soc. 1970, 92, 2953-2956.
(32) Beachley, O. T., Jr.; Tessier-Youngs, C. Inorg. Chem. 1979, 18,
3188-3191.
(33) Davies, R. P.; Martinelli, M. G. Inorg. Chem. 2002, 41, 348-352.
(34) Planas, J. G.; Hampel, F.; Gladysz, J. A. Chem. Eur. J. 2005, 11,
1402-1416.
(35) (a) Beachley, O. T., Jr.; Bueno, C.; Churchill, M. R.; Hallock, R.
B.; Simmons, R. G. Inorg. Chem. 1981, 20, 2423-2428. (b) Beachley, O.
T., Jr.; Royster, T. L., Jr.; Arhar, J. R.; Rheingold, A. L. Organometallics
1993, 12, 1976-1980. (c) Sauls, F. C.; Czekaj, C. L.; Interrante, L. V.
Inorg. Chem. 1990, 29, 4688-4692.

Assembly of Polynuclear Complexes
Organometallics, Vol. 25, No. 23, 2006 5597
Scheme 1
Figure 3. ORTEP depiction of the solid-state molecular structure
of 3c as determined by X-ray crystallography. Ellipsoids are drawn
at the 50% probability level, and hydrogen atoms are omitted for
clarity. Selected distances (Å): Se(1)-P(1), 2.2793(7); Se(1)-Al-
(2), 2.4909(9); Se(1)-Al(3), 2.4979(9); P(1)-C(1), 1.852(3); P(1)-
C(2), 1.846(3); N(2)-Al(2), 1.991(2); N(1)-Al(3), 1.977(2); N(1)-
Al(1), 1.996(2); N(2)-Al(1), 2.005(2). Selected bond angles
(deg): C(1)-P(1)-C(2), 99.06(11); C(1)-P(1)-Se(1), 101.23(8);
C(2)-P(1)-Se(1), 100.65(8); Al(2)-Se(1)-P(1), 91.85(3); Al(3)-
Se(1)-P(1), 90.37(3); Al(3)-Se(1)-Al(2), 104.00(3).
loss occurs is not clear, and a mechanism with an imine
intermediate (CH2dNArR) cannot be distinguished from the
direct reaction of the ligand precursors with AlMe3 to liberate
CH3CH2N(ArR)AlMe2.
The solid-state molecular structures of 3a and 3c were
determined by X-ray crystallography. Complex 3b crystallized
as thin needles that were unsuitable for crystallographic studies.
An ORTEP depiction of the structure of 3c is shown in Figure
3. Although there is no crystallographically imposed symmetry,
1
ized. The η2-binding mode has been observed in complexes of
Mo39 and Ru,40 but for the more electropositive metals the only
crystallographically characterized structure is that of the lithium
salt, [(TMEDA)Li-µ-η1-SePPh2]2;33 however, it is reasonable
to assume that the selenophosphinito complexes of the electro-
positive metals will be comparable to those of the thiophos-
phinito ligands, which prefer to coordinate metals via the
chalcogenide,42 as is observed in complexes 3a-c.
these complexes have approximate Cs symmetry. The H and
13C{1H} spectra of these complexes dissolved in C6D6 are
consistent with an identical solution structure.
The tripodal ligand in 3c binds three aluminum centers via
one selenide and two amide donors, all of which act as bridging
ligands. The three aluminum centers all have approximately
tetrahedral geometries, and each retains two methyl groups. The
lone pair of the phosphine donor is directed away from the
aluminum centers. The donors and aluminum atoms form a six-
membered Al3N2Se ring, which adopts a chair conformation.
The Al-N bond lengths in 3a and 3c vary from 1.977(2) to
2.0137(18) Å, and the Al-Se bond lengths range from 2.4760-
(8) to 2.4979(9) Å. These lengths, as well as the N-Al-N
angles (3a, 102.85(8)°; 3c, 102.65(7)°), are in the expected
range.14,15,18,21,36 Both the P-Se bond lengths (e.g., 3a: 2.2799-
(6) Å; 3c, 2.2793(7) Å) and the1JSeP values (3a, 176.2 Hz; 3b,
179.0 Hz; 3c, 181.3 Hz) are within the range expected for P-Se
single bonds,37 and thus the selenophosphinito donor in this case
is best described by a resonance structure where the selenium
atom bears a formal negative charge, rather than one where the
phosphorus donor is formally anionic.10 As expected, complexes
3a-c exhibit lower 1JSeP values than in related complexes, such
as Me2Al[PhP(Se)(NtBu)(NHtBu)]],12 where the anionic charge
of the ligand can be delocalized between the nitrogen and
selenium donors.
Trimethylaluminum Adducts of [P(CH2NArR)2Se](AlMe2)3.
The reaction of 2b,c with excess AlMe3 provides the adducts
Me3Al‚P(CH2NArR)2Se(AlMe2)3 (4b,c) at room temperature,
which can also be obtained by the addition AlMe3 to 3b,c, as
shown in Scheme 1. The trimethylaluminum adduct of 3a is
too thermally unstable to be isolated in the solid state. Both 4b
and 4c were obtained as white crystalline solids at room
temperature and in this state are stable with respect to
decomposition for several days. Single crystals of 4b suitable
for X-ray diffraction were obtained from toluene at -30 °C.
The solid-state molecular structure is shown in Figure 4, along
with selected bond lengths and bond angles.
The solid-state molecular structure of 4b has crystallographi-
cally imposed Cs symmetry. The connectivity is the same as
that observed for 3b, but with an additional AlMe3 moiety bound
to the phosphine lone pair. The Al-P distance of 2.553(2) Å is
significantly elongated in comparison to the sum of the covalent
radii (2.350 Å) of Al and P, but within the range observed for
aluminum-phosphine adducts.43,44 In the solid-state structure
of 4b the sum of C-Al(3)-C angles is 353.24(39)°, which is
close to that for a trigonal planar system. The C(12,13)-Al(3)
Chalcogenophosphinites (R2PE-, where E ) O, S, Se, or Te)
can be protonated at either the P or E sites to provide the
tautomers R2P(H)dE and R2P-EH.10,38 The ratio of these
products depends on the nature of R. Likewise, transition metals
can bind to R2PE- ligands by a variety of bonding modes
involving either the E or P centers, or both.10 Only a handful
of examples of complexes containing R2PSe- donors have been
reported,10,33,34,39-41 and few have been structurally character-
(39) Lindner, E.; Bosch, E.; Fawzi, R.; Steimann, M.; Mayer, H. A.;
Gierling, K. Chem. Ber. 1996, 129, 945-951.
(40) Zhang, Q.-F.; Cheung, F. K. M.; Wong, W.-Y.; Williams, I. D.;
Leung, W.-H. Organometallics 2001, 20, 3777-3781.
(41) Walther, B.; Messbauer, B.; Meyer, H. Inorg. Chim. Acta 1979,
37, L525-L527.
(42) Gelmini, L.; Stephan, D. W. Organometallics 1987, 6, 1515-1522.
(43) Wells, R. L.; Foos, E. E.; Rheingold, A. L.; Yap, G. P. A.; Liable-
Sands, L. M.; White, P. S. Organometallics 1998, 17, 2869-2875.
(44) Kuczkowski, A.; Schulz, S.; Nieger, M.; Schreiner, P. R. Organo-
metallics 2002, 21, 1408-1419.
(36) (a) Himmel, H.-J.; Vollet, J. Organometallics 2002, 21, 5972-5977.
(b) Zhu, H.; Yang, Z.; Magull, J.; Roesky, H. W.; Schmidt, H.-G.;
Noltemeyer, M. Organometallics 2005, 24, 6420-6425.
(37) Duddeck, H. Prog. Nucl. Magn. Reson. Spectrosc. 1995, 27, 1-323.
(38) Leszczynski, J.; Kwiatkowski, J. S. J. Phys. Chem. 1993, 97, 1364-
1367.

5598 Organometallics, Vol. 25, No. 23, 2006
Han and Johnson
1
and -9.4 and display selenium satellites with JSeP values of
349.4 and 312.0 Hz, respectively. The change in the 31P
chemical shifts upon forming the adducts 4b,c from 3b,c to
slightly higher field is fairly typical for phosphine donors with
moderately large cone angles (∆δ ) -4.3 for b; -6.0 for c).44
1
The JSeP values are within the range expected for the P-Se
single bonds,37 but much greater than the values observed for
3b,c. Moreover, the difference in these 1JSeP values of 37.4 Hz
is much larger than in complexes 3b,c, where the difference in
1
1JSeP is only 2.3 Hz. The vastly different JSeP values in 4b,c
indicate a large influence of the aryl substituents on the bonding
in these complexes and their importance in determining the
relative contributions of the resonance structures shown in
Scheme 2.
Aluminum Complexes with the P(CH2NArR)3 Ligands.
The tripodal diamidoselenophosphinito ligand in 3a-c and 4b,c
promote the formation of triangular complexes, which is not
typical of tripodal ligands,22 and a comparison to the parent
P(CH2NArR)3 ligands was desired to determine what factors
might favor triangular trinuclear complex formation. The room-
temperature reactions of 1a-c with 2 equiv of AlMe3 over 24
h cleanly provide the bimetallic aluminum amido complexes
[P(CH2NArR)3]Al2Me3 (5a-c) as white crystalline solids, as
Figure 4. Solid-state molecular structure of 4b as determined by
X-ray crystallography. Ellipsoids are drawn at the 50% probability
level, and hydrogen atoms are omitted for clarity. Selected distances
(Å): Al(3)-P(1), 2.553(2); Al(3)-C(13), 1.958(5); Al(3)-C(12),
1.951(7); Se(1)-P(1), 2.2388(16); Se(1)-Al(1), 2.5104(13); P(1)-
C(1), 1.822(4); N(1)-Al(1), 1.990(3); N(1)-Al(2), 2.011(3).
Selected bond angles (deg): C(1)-P(1)-C(1), 101.4(3); C(1)-
P(1)-Se(1), 103.61(13); C(1)-P(1)-Al(3), 118.84(13); Al(1)-Se-
(1)-Al(1), 104.07(6); P(1)-Se(1)-Al(1), 89.86(4); N(1)-Al(1)-
Se(1), 93.83(11); Al(1)-N(1)-Al(2), 122.26(17); C(1)-N(1)-
Al(1), 104.1(2); C(1)-N(1)-Al(2), 108.2(2); C(12)-Al(3)-C(13),
119.12(18); C(13)-Al(3)-C(13), 115.0(3); C(13)-Al(3)-P(1),
97.45(16); C(12)-Al(3)-P(1), 101.1(3).
1
shown in Scheme 3. The H and 13C{1H} spectra of these
complexes in C6D6 are consistent with complexes of Cs
symmetry with the connectivity shown. For example, there are
three Al-Me environments of equal intensities observed in the
1H NMR of each of these complexes, and three PCH2 environ-
ments are observed, in a 2:2:2 ratio, a pair of which are due to
diastereotopic environments.
The solid-state structure of 5a was determined by X-ray
crystallography and is depicted in Figure 5. The triamidophos-
phine ligand binds to a central AlMe fragment with three
nitrogen atoms, and two of these amido donors bridge to an
AlMe2 moiety. The phosphine donor is directed away from the
central aluminum atom. Both geometries around the two
aluminum centers are distorted tetrahedral.
bond lengths range from 1.951(7) to 1.958(5) Å, which are
almost identical to that of free AlMe3.45 The change in 13C-
{1H} NMR chemical shifts of the Al-Me3 groups (4b, δ -8.0;
4c, -7.8; free AlMe3, -8.1) are small, which also indicates
only a slight distortion from planarity upon adduct formation.26
All these factors are consistent with the poor σ-donor ability of
the phosphine toward AlMe3 in 4b and 4c.
For example, the N(2)-Al(2)-N(3) angle of 81.40(9)° is
more acute than the C(29)-Al(2)-C(30) angle of 117.77(17)°.
The bond length of 1.964(2) Å for Al(1)-N(2) is about 0.032
Å shorter than that of 1.996(3) Å for Al(2)-N(2), but both
distances are considerably longer than the terminal amido Al-
(1)-N(1) bond length of 1.829(3) Å. The aromatic substituent
on the terminal amido donor is aligned such that its π-system
has considerable overlap with the lone pair on the nitrogen,
whereas the aromatic substitutents associated with the bridging
amido donors are aligned so the that aromatic π-system is nearly
orthogonal to the lone-pair p-orbital.
The reaction of the triaminophosphines (1b,c) with excess
AlMe3 at room temperature provides the Lewis acid-base
adducts of 5b,c, Me3Al‚P(CH2NArR)3Al2Me3 (6b,c). These
complexes could also be generated by the addition of AlMe3 to
5b,c, as shown in Scheme 3. Similar to 3a, adducts of 5a could
The binding of trimethylaluminum to the phosphine donor
in 4b has an effect on the ancillary ligand bond lengths. In
particular, the P-Se bond length of 2.2388(16) Å in 4b is
approximately 0.04 Å shorter than in either 3a or 3c. Addition-
ally, the Se(1)-Al(1) bond length of 2.5104(13) Å in 4b is
slightly longer than the Se-Al bond lengths in 3a, which are
2.4760(8) and 2.4866(8) Å, or in 3c, where the bond lengths
are 2.4909(9) and 2.4979(9) Å. These bond lengths can be
interpreted in terms of a slight contribution from resonance
structures where the phosphorus atom is formally an anionic
P(V) donor,10 as shown in Scheme 2, though the structure is
still best described by the resonance structure containing a P-Se
single bond.
1
The H NMR spectra of 4b,c are consistent with the Cs
symmetry observed in the solid-state structure of 4b. The 31P-
{1H} NMR spectra of 4b and 4c consist of singlets at δ -8.4
Scheme 2

Assembly of Polynuclear Complexes
Organometallics, Vol. 25, No. 23, 2006 5599
Scheme 3
not be isolated. Single crystals of 6b suitable for X-ray
diffraction were obtained from toluene at -30 °C. An ORTEP
depiction is shown in Figure 6, along with selected bond lengths
and bond angles.
Figure 5. Solid-state molecular structure of 5a as determined by
X-ray crystallography. Ellipsoids are drawn at the 50% probability
level, and hydrogen atoms are omitted for clarity. Selected distances
(Å): P(1)-C(1), 1.844(3); P(1)-C(2), 1.844(3); P(1)-C(3), 1.856-
(3); N(1)-Al(1), 1.829(3); N(2)-Al(1), 1.964(2); N(3)-Al(1),
1.958(2); N(2)-Al(2), 1.996(3); N(3)-Al(2), 1.997(2); C(28)-Al-
(1), 1.930(3); C(29)-Al(2), 1.948(4); C(30)-Al(2), 1.947(4).
Selected bond angles (deg): C(1)-P(1)-C(2), 99.06(15); C(1)-
P(1)-C(3), 101.71(14); C(2)-P(1)-C(3), 103.39(14); N(1)-Al-
(1)-C(28), 119.30(14); N(1)-Al(1)-N(2), 111.15(11); N(1)-
Al(1)-N(3), 107.67(11); N(2)-Al(1)-N(3), 83.18(10); C(29)-
Al(2)-C(30), 117.77(17); N(2)-Al(2)-C(29), 110.60(14); N(3)-
Al(2)-C(29), 114.06(13); N(2)-Al(2)-N(3), 81.40(10).
The connectivity in 6b is essentially the same as that observed
for complexes 5a-c, but with an additional AlMe3 moiety bound
to the phosphine lone pair. The sum of C-Al(3)-C angles is
351.25(43)°, and C-Al(3) bond lengths range from 1.946(3)
to 1.966(3) Å. The small change in 13C chemical shift of Al-
Me3 groups also indicates the slight distortion from planarity
of aluminum.44 The 31P{1H} NMR spectra of 6b and 6c contain
resonances at δ -45.5 and -44.5, respectively, which are shifted
to lower field by approximately +6 ppm compared to com-
pounds 5b,c. Adduct 6b has slightly longer Al-C bond distances
and smaller C-Al-C angles for the AlMe3 moeity than in 4b,
which indicates that slightly stronger Lewis acid-base interac-
tions occur in 6b.36 This is consistent with the shorter Al-P
distance of 2.5151(7) Å in 6b than that of 2.553(2) Å in 4b.
Ligand Design and Bonding Modes. Both the amido and
selenophosphinito donors show a propensity to bridge, and so
this cannot be the only factor that leads to the formation of
triangular complexes for 3a-c, but not for 5a-c. To improve
these ligand designs to assemble triangular complexes with a
variety of metal precursors requires a better understanding of
what factors promote polynuclear complex formation. The
geometry of the ligand plays a role in the assembly of the
trinuclear complexes in the case of 3a-c. For the supporting
diamidoselenophosphinito donor to chelate all its anionic donors
to a central aluminum atom would require the formation of a
[2.2.1] bicyclic. The resultant two five-membered rings and one
six-membered ring seem ideal in terms of chelate ring sizes,
but the fused nature of these rings leads to considerable strain
and results in less than tetrahedral bond angles. For example,
the analogous hydrocarbon norbornane possesses 71.8 kJ/mol
of ring strain.46
1
the JSeP values as well the sensitivity of these values to the
nature of ArR indicates that considerable delocalization of
bonding occurs. These ligands may be an improvement to the
P(CH2NHArR)3 ligands for the formation of polynuclear clusters
of paramagnetic metals, where strong magnetic coupling
between metal centers is desired, due to the increased polariz-
ability of the selenophosphinito donor relative to amido donors.
The P(CH2NHArR)3 ligand precursors show no propensity
to form triangular trinuclear structures, instead forming the
dinuclear complexes [P(CH2NArR)3]Al2Me3 and the adducts
Me3Al‚[P(CH2NArR)3]Al2Me3. The preference of the diami-
doselenophosphinito ligands in 3a-c to form trinuclear struc-
tures, as opposed to adopting a κ Se,N,N bonding mode similar
to the κ N,N,N bonding observed in complexes 5a-c, can be
ascribed to the ring strain associated with [2.2.1] bicyclic
systems. We are currently investigating the coordination chem-
istry of these ligands with trivalent first-row transition metals
in an attempt to generate paramagnetic analogues of these
diamagnetic polynuclear aluminum complexes.
Experimental Section
General Procedures. All experiments were performed under an
inert atmosphere of nitrogen using either standard Schlenk tech-
niques or an MBraun glovebox. Dry, oxygen-free solvents were
employed throughout. Anhydrous pentane and toluene were pur-
chased from Aldrich, sparged with dinitrogen, and passed through
activated alumina under a positive pressure of nitrogen gas.
Deuterated benzene was dried by heating at reflux with sodium/
potassium alloy in a sealed vessel under partial pressure, then trap-
to-trap distilled and freeze-pump-thaw degassed three times. NMR
spectra were recorded on a Bruker AMX (300 MHz) or Bruker
AMX (500 MHz) spectrometer. All chemical shifts are reported in
ppm, and all coupling constants are in Hz. For 19F NMR spectra,
trifluoroacetic acid was used as the external reference at 0.00 ppm.
1H NMR spectra were referenced to residual protons (C6D5H, δ
7.15). 31P{1H} NMR spectra were referenced to external 85% H3-
Conclusions
The reaction of the ligand precursors SedP(CH2NHArR)3
(2a-c) with 4 equiv of AlMe3 provides facile synthetic routes
to triangular trinuclear complexes (3a-c) of the unanticipated
diamidoselenophosphinito ligands, with concomitant loss of 1
equiv of [Et(ArR)NAlMe2]n. Tetranuclear complexes can be
obtained by the formation of adducts with AlMe3 at the
phosphine donor. The large influence of adduct formation on
(45) Almenningen, A.; Halvorsen, S.; Haaland, A. Acta Chem. Scand.
1971, 25, 1937-1945.
(46) Verevkin, S. P.; Emel’yanenko, V. N. J. Phys. Chem. A 2004, 108,
6575-6580.

5600 Organometallics, Vol. 25, No. 23, 2006
Han and Johnson
were grown from a mixture of ethanol (50%) and acetone (50%)
at -30 °C. 1H NMR (C6D6, 300 MHz, 298 K): δ 3.30 (dd, 3JHH
)
5.6 Hz, 2JPH ) 5.6 Hz, 6H, PCH2), 3.95 (b, 3H, NH), 6.36 (d, 3JHH
) 8.5 Hz, 6H, Ph o-H), 6.71 (t, 3JHH ) 7.5 Hz, 3H, Ph p-H), 7.03
(m, 6H, Ph m-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ
42.1 (d, JPC ) 47.8 Hz, PCH2), 114.5 and 119.9 (s, Ph o-C and
m-C), 130.1 (s, Ph p-C), 147.6 (d, J ) 7.1 Hz, ipso-C). 31P{1H}
NMR (C6D6, 121.5 MHz, 298 K): δ 46.3 (s with satellites, JSeP
)
719.7 Hz.). 77Se{1H} NMR (C6D6, 57.2 MHz, 298 K): δ -455.2
(d, JSeP ) 720.8 Hz.). Anal. Calcd for C21H24N3PSe: C, 58.88; H,
5.65; N, 9.81. Found: C, 58.95; H, 5.47, N, 9.44.
Preparation of SedP(CH2NH-3,5-Me2C6H3)3 (2c). 2c was
prepared in an analogous manner to 2a using P(CH2NH-3,5-
Me2C6H3)3 (1c) (1.75 g, 5 mmol) in lieu of 1a with a yield of 2.22
g, 87%. Single crystals were grown from a mixture of ethanol (50%)
and acetone (50%) at -30 °C. 1H NMR (C6D6, 300 MHz, 298 K):
3
2
δ 2.18 (s, 18H, PhCH3), 3.51 (dd, JHH ) 5.7 Hz, JPH ) 5.7 Hz,
6H, PCH2), 4.05 (b, 3H, NH), 6.16 (s, 6H, Ph o-H), 6.40 (s, 3H,
Ph p-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ 21.8 (s,
PhCH3), 42.1 (d, JPC ) 47.2 Hz, PCH2), 112.5 and 121.9 (s, Ph
o-C and m-C), 139.4 (s, Ph p-C), 147.6 (d, J ) 7.1 Hz, ipso-C).
31P{1H} NMR (C6D6, 121.5 MHz, 298 K): δ 44.46 (s with
satellites, JSeP ) 716.1 Hz.). 77Se{1H} NMR (C6D6, 57.2 MHz, 298
K): δ -453.2 (d, JSeP ) 716.9 Hz). Anal. Calcd for C27H36N3PSe:
C, 63.27; H, 7.08; N, 8.20. Found: C, 63.51; H, 6.9; N, 7.93.
Figure 6. ORTEP depiction of the solid-state molecular structure
of 6b as determined by X-ray crystallography. Ellipsoids are drawn
at the 50% probability level, and hydrogen atoms are omitted for
clarity. Selected distances (Å): P(1)-Al(3), 2.5151(7); P(1)-C(1),
1.8222(18); P(1)-C(2), 1.8328(19); P(1)-C(3), 1.8426(18); N(1)-
Al(1), 1.8253(16); N(2)-Al(1), 1.9903(16); N(3)-Al(1), 1.9645-
(15); N(2)-Al(2), 1.9970(15); N(3)-Al(2), 1.9833(16); C(22)-
Al(1), 1.9474(19); C(24)-Al(2), 1.945(2); C(23)-Al(2), 1.947(2);
Al(3)-C(25), 1.960(2); Al(3)-C(26), 1.966(3); Al(3)-C(27),
1.946(3). Selected bond angles (deg): C(1)-P(1)-C(2), 101.96-
(9); C(1)-P(1)-C(3), 104.48(8); C(2)-P(1)-C(3), 105.72(8);
C(2)-P(1)-Al(3), 114.35(6); C(3)-P(1)-Al(3), 112.73(6); N(1)-
Al(1)-C(22), 118.28(8); N(1)-Al(1)-N(2), 110.19(7); N(1)-Al-
(1)-N(3), 107.88(7); N(2)-Al(1)-N(3), 82.66(6); C(23)-Al(2)-
C(24), 117.82(9); N(2)-Al(2)-C(24), 113.97(8); N(3)-Al(2)-
C(24), 115.08(8); N(2)-Al(2)-N(3), 82.02(6); C(26)-Al(3)-
C(27), 116.59(16); C(25)-Al(3)-C(26), 117.39(12); C(25)-Al(3)-
C(27), 117.27(15); C(27)-Al(3)-P(1), 101.32(9); C(26)-Al(3)-
P(1), 99.28(8); C(25)-Al(3)-P(1), 99.23(7).
Preparation of P[CH2N-3,5-(CF3)2C6H3]2Se(AlMe2)3 (3a). A
2.0 M solution of AlMe3 in toluene (2.0 mL, 4.0 mmol) was added
to a solution of 2a (836.1 mg, 1 mmol) in 25 mL of toluene. The
solution was stirred at room temperature for 24 h. The solution
was evaporated to dryness, and the remaining solid was rinsed by
pentane. The white solid was collected by filtration and dried (382
mg, 50%). X-ray-quality crystals were obtained from slow evapora-
1
tion of a benzene solution. H NMR (C6D6, 300 MHz, 298 K): δ
-1.71 and -0.28 (s, 3H each, N,N′-AlMe2), -0.98 and 0.05 (s,
6H each, Se, N-AlMe2), 2.93 (s, 2H, PCH2), 2.95 (d, 2H, PCH2),
7.44 (s, 2H, Ph o-H), 7.69 (s, 4H, Ph p-H). 13C{1H} NMR (C6D6,
125.8 MHz, 298 K): δ -9.4, -7.9, -3.9, and -2.8 (s, AlMe2), δ
46.4 (d, JPC ) 41.2 Hz, PCH2), 118.3 and 123.5 (s, Ph o-C and
m-C), 121.5 (s, Ph p-C), 133.6 (q, J ) 33.4 Hz, PhC-F3), 148.0 (s,
ipso-C). 31P{1H} NMR (C6D6, 202.5 MHz, 298 K): δ -4.7 (s with
satellites, JSeP ) 176.2 Hz). 19F NMR (C6D6, 282.1 MHz, 298 K):
δ 14.81 (s). 77Se{1H} NMR (C6D6, 121.5 MHz, 298 K): δ -430.0
(d, JSeP ) 176.6 Hz). Anal. Calcd for C24H28Al3F12N2PSe: C, 37.76;
H, 3.70; N, 3.67. Found: C, 38.20; H, 3.58; N, 3.76.
PO4 at δ 0.0. 13C{1H} NMR spectra were referenced relative to
solvent resonances (C6D6, δ 128.0). 77Se{1H} spectra were refer-
enced relative to external Me2Se in CDCl3. Elemental analyses were
performed by the Centre for Catalysis and Materials Research
(CCMR), Windsor, Ontario, Canada. The ligand precursors P(CH2-
NHArR)3 (1a-c) were prepared as previously reported.7 Selenium
powder and 2.0 M AlMe3 in toluene were purchased from Aldrich
and used as received.
The pentane rinse was hydrolyzed with water, with the evolution
of gas. The sample was extracted into C6D6 and passed through a
short plug of alumina. 1H NMR (C6D6, 300 MHz, 298 K): δ 0.62
Preparation of SedP[CH2NH-3,5-(CF3)2C6H3]3 (2a). Selenium
(789 mg, 10 mmol) was added to a solution of P(CH2NH-3,5-
(CF3)2C6H3)3 (1a) (3.78 g, 5 mmol) in 50 mL of toluene. The
solution was stirred 24 h and then filtered to remove the excess
selenium. The solvent was removed under vacuum, and the
remaining white solid was rinsed with a small portion of pentane
and then dried under vacuum (3.55 g, 85%). Single crystals were
grown from a mixture of ethanol (50%) and acetone (50%) at -30
3
3
(t, 3H, JHH ) 7.3 Hz, CH2CH3), 2.26 (qd, 2H, JHH ) 7.3 Hz,
3JHH ) 5.2 Hz, NHCH2CH3), 5.2 (br, 1H, NH), 6.42 (s, 2H, Ph
o-H), 7.21 (s, 1H, Ph p-H), consistent with EtN(H)-3,5-(CF3)2C6H3.
Preparation of P(CH2NPh)2Se(AlMe2)3 (3b). 3b was prepared
in an analogous manner to 3a using 2b (428.4 mg, 1.0 mmol) in
lieu of 2a with an isolated yield of 245.6 mg, 50%. 1H NMR (C6D6,
300 MHz, 298 K): δ -1.36 and -0.04 (s, 3H each, N,N′-AlMe2),
-0.81, 0.23 (s, 6H each, Se, N-AlMe2), 3.24 and 3.24 (m, 4H total,
PCH2), 6.81 (t, 2H, J ) 7.3 Hz, Ph p-H), 7.0 (dd, 4H, Ph m-H),
7.17 (d, 4H, Ph o-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K):
δ -15.1, -8.6, -5.8, and -2.7 (s, AlMe2), δ 46.7 (d, JPC ) 36.5
Hz, PCH2), 122.05 and 125.5 (s, Ph o-C and m-C), 130.0 (s, Ph
p-C), 145.9 (s, ipso-C). 31P{1H} NMR (C6D6, 202.5 MHz, 298 K):
δ -4.1 (s with satellites, JSeP ) 179.0 Hz). 77Se{1H} NMR (C6D6,
121.5 MHz, 298 K): δ -433.0 (d, JSeP ) 179.9 Hz.). Anal. Calcd
for C20H32Al3N2PSe: C, 48.89; H, 6.56; N, 5.70. Found: C, 48.48;
H, 6.23; N, 5.89.
1
3
°C. H NMR (C6D6, 300 MHz, 298 K): δ 2.77 (dd, JHH ) 5.8
2
Hz, JPH ) 5.2 Hz, 6H, PCH2), 3.94 (q, 3H, NH), 6.56 (s, 6H, Ph
o-H), 7.28 (s, 3H, Ph p-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298
K): δ 40.3 (d, JPC ) 49.4 Hz, PCH2), 113.3 and 122.4 (s, Ph o-C
and m-C), 113.6. (s, Ph p-C), 133.4 (q, J ) 33.5 Hz, PhC-F3), 147.8
(d, J ) 8.8 Hz, ipso-C). 31P{1H} NMR (C6D6, 121.5 MHz, 298
K): δ 42.6 (s with satellites, JSeP ) 742.8 Hz.). 77Se{1H} NMR
(C6D6, 121.5 MHz, 298 K): δ -463.8 (d, JSeP ) 743.3 Hz.). 19F
NMR (C6D6, 282.1 MHz, 298 K): δ 14.68 (s). Anal. Calcd for
C27H18F18N3SeP: C, 38.75; H, 2.17; N, 5.02. Found: C, 39.1; H,
2.46; N, 5.06.
Preparation of SedP(CH2NHPh)3 (2b). 2b was prepared in
an analogous manner to 2a using P(CH2NHPh)3 (1b) (1.75 g, 5
mmol) in lieu of 1a with a yield of 1.92 g, 80%. Single crystals
Preparation of P(CH2N-3,5-Me2C6H3)2Se(AlMe2)3 (3c). 3c was
prepared in an analogous manner to 3a using 2c (512.5 mg, 1.0
mmol) in lieu of 2a with an isolated yield of 328.5 mg, 60%. X-ray-

Assembly of Polynuclear Complexes
Organometallics, Vol. 25, No. 23, 2006 5601
quality crystals were obtained from slow evaporation of a benzene
solution. 1H NMR (C6D6, 300 MHz, 298 K): δ -1.24 and 0.03 (s,
3H each, N,N′-AlMe2), -0.74 and 0.30 (s, 6H each, Se, N-AlMe2),
2.05 (s, 12H, PhCH3), 3.30 (s, 2H, PCH2), 3.32 (d, 2H, PCH2),
6.51 (s, 2H, Ph o-H), 6.96 (s, 4H, Ph p-H). 13C{1H} NMR (C6D6,
125.8 MHz, 298 K): δ -14.8, -8.4, -5.6, and -2.3 (s, AlMe2),
21.8 (s, PhCH3), 46.7 (d, JPC ) 37.3 Hz, PCH2), 120.1 and 127.4
(s, Ph o-C and m-C), 137.8 (s, Ph p-C), 146.1 (s, ipso-C). 31P{1H}
124.6 (s, Ph p-C), 129.9 (m, PhC-F3), 149.4 (s, ipso-C). 31P{1H}
NMR (C6D6, 202.5 MHz, 298 K): δ -54.2 (s). 19F NMR (C6D6,
282.1 MHz, 298 K): δ 14.67 (s). Anal. Calcd for C30H24-
Al2F18N3P: C, 42.22; H, 2.84; N, 4.92. Found: C, 41.77; H, 3.30;
N, 4.89.
Preparation of P(CH2NPh)3Al2Me3 (5b). A solution of AlMe3
in toluene (1 mL, 2.0 M, 2 mmol) was added to a solution of 1b
(349.4 mg, 1 mmol) in 25 mL of toluene. The solution was stirred
at room temperature for 24 h. The solution was evaporated to
dryness, and the remaining solid was rinsed by pentane prior to
crystallization from benzene. The white solid was collected by
NMR (C6D6, 202.5 MHz, 298 K): δ -3.4 (s with satellites, JSeP
)
181.3 Hz). 77Se{1H} NMR (C6D6, 121.5 MHz, 298 K): δ -434.9
(d, JSeP ) 182.7 Hz). Anal. Calcd for C24H40Al3N2PSe: C, 52.65;
H, 7.36; N, 5.12. Found: C, 52.29; H, 6.99; N, 4.75.
1
filtration and dried (328.5 mg, 60%). H NMR (C6D6, 500 MHz,
298 K): δ -0.6, 0.22, and -0.16 (s, 3H each, AlMe), 3.14 (d, 2H,
J ) 14.2 Hz, PCH), 3.53 (d, 2H, J ) 6.8 Hz, PCH2), 4.00 (dd, 2H,
2JHH )14.2 Hz, 2JPH )16.6 Hz PCH), 6.86 and 6.88 (m, 3H total,
p-H), 6.96 (dd, 4H, J ) 7.7 Hz, m-H), 7.09 (d, 4H, J ) 7.7 Hz,
o-H), 7.22 (d, 2H, J ) 8.1 Hz, o-H), 7.33 (dd, 2H, m-H). 13C{1H}
NMR (C6D6, 125.8 MHz, 298 K): δ -11.1, -9.2, and -7.9 (s,
AlMe2), 49.7 (d, JPC ) 12.9 Hz, PCH2), 55.5 (d, JPC ) 27.0 Hz
PCH2), 116.8, 118.3, 125.8, 125.9, 129.5, and 130.1 (s, Ph o-C,
m-C, and p-C), 150.6 and 154.6 (s, ipso-C). 31P{1H} NMR (C6D6,
202.5 MHz, 298 K): δ -51.3 (s). Anal. Calcd for C24H30Al2N3P:
C, 64.71; H, 6.79; N, 9.43. Found: C, 64.51; H, 6.93; N, 9.74.
Preparation of Me3Al‚P(CH2NPh)2Se(AlMe2)3 (4b). A solution
of AlMe3 in toluene (3.0 mL, 2.0 M, 6.0 mmol) was added to a
solution of 2b (428.4 mg, 1.0 mmol) in 25 mL of toluene. The
solution was stirred at room temperature for 24 h. The solution
was evaporated to dryness, and the remaining solid was rinsed by
pentane. The white solid was collected by filtration and dried (310
mg, 55%). X-ray-quality crystals were obtained from toluene
1
solution at -30 °C. H NMR (C6D6, 300 MHz, 298 K): δ -1.04
and -0.69 (s, 3H each, N,N′-AlMe2), -0.80, 0.13, (s, 6H, Se,
N-AlMe2), -0.46 (s, 9H, P-AlMe3), 3.54 (m, 4H, PCH2), 2.83 (m,
2H, PCH2), 6.81 (m, 4H, Ph o-H), 7.07 (m, 6H, Ph p-H and Ph
m-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ -14.7, -8.5,
-5.4, and -2.1 (s, AlMe2), -8.0 (s, P-AlMe3), 46.3 (d, JPC ) 36.7
Hz, PCH2), 121.05 and 126.0 (s, Ph o-C and m-C), 130.0 (s, Ph
p-C), 145.6 (s, ipso-C). 31P{1H} NMR (C6D6, 202.5 MHz, 298 K):
δ -8.4 (s with satellites, JSeP ) 349.4 Hz). 77Se{1H} NMR (C6D6,
121.5 MHz, 298 K): δ -435.0 (d, JSeP ) 349.7 Hz). Anal. Calcd
for C23H41Al4N2PSe: C, 49.03; H, 7.33; N, 4.91. Found: C, 49.43;
H, 6.99; N, 4.87.
Preparation of P(CH2N-3,5-Me2C6H3)3Al2Me3 (5c). A solution
of AlMe3 in toluene (1 mL, 2.0 M, 2 mmol) was added to a solution
of 1c (433.6 mg, 1 mmol) in 25 mL of toluene. The solution was
stirred at room temperature for 24 h. The solution was evaporated
to dryness, and the remaining solid was rinsed by pentane prior to
crystallization from benzene. The white solid was collected by
1
filtration and dried (413.5 mg, 78%). H NMR (C6D6, 500 MHz,
298 K): δ -0.45, -0.1, and -0.02 (s, 3H each, AlMe), 2.0 (s,
2
12H, PhCH3), 2.33 (s, 6H, PhCH3), 3.30 (dd, 2H, JPH ) 1.2 Hz,
Preparation of Me3Al‚P(CH2N-3,5-Me2C6H3)2Se(AlMe2)3 (4c).
A solution of AlMe3 in toluene (3 mL, 2.0 M, 6 mmol) was added
to a solution of 2c (512.5 mg, 1 mmol) in 25 mL of toluene. The
solution was stirred at room temperature for 24 h. The solution
was evaporated to dryness, and the remaining solid was rinsed by
pentane. The white solid was collected by filtration and dried (403
mg, 65%). 1H NMR (C6D6, 300 MHz, 298 K): δ -0.837 and -0.63
(s, 3H each, N,N′-AlMe2), -0.171 and 0.291 (s, 6H each, Se,
N-AlMe2), -0.447 (s, 9H, P-AlMe3), 1.866, 1.994 (s, 6H each,
PhCH3), 2.56 (dd, 1H, PCH2), 3.50 (m, 1H, PCH2), 3.67 (m, 1H,
PCH2), 3.86 (dd, 1H, PCH2), 6.5 (s, 2H, Ph o-H), 6.6 (s, 4H, Ph
p-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ -14.1, -8.1,
-2.25, and -1.63 (s, AlMe2), -7.8 (s, P-AlMe3), 21.8 (s, PhCH3),
δ 47.3 (m, PCH2), 120.0 and 127.5 (s, Ph o-C and m-C), 142.7 (s,
Ph p-C), 146.1 (d, J ) 19.5 Hz, ipso-C). 31P{1H} NMR (C6D6,
202.5 MHz, 298 K): δ -9.4 (s with satellites, JSeP ) 312.0 Hz).
2
2JHH ) 14.3 Hz, PCH2), 3.64 (d, 2H, JPH ) 6.5 Hz, PCH), 4.16
2
(dd, 2H, JHH ) 14.3 Hz, PCH2), 6.56 (s, 1H, Ph o-H), 6.58 (s,
1H, Ph o-H), 6.95 (s, 6H, Ph p-H). 13C{1H} NMR (C6D6, 125.8
MHz, 298 K): δ -19.8, -7.3, and -5.8 (s, AlMe), 21.4 (s, PhCH3),
22.3 (s, PhCH3), 50.5 (d, PCH2), 56.0 (d, PCH2), 115.5, 120.5,
124.0, and 140.1 (s, Ph o-C and p-C), 151.1 and 155.1 (s, ipso-C).
31P{1H} NMR (C6D6, 202.5 MHz, 298 K): δ -50.5 (s). C30H42-
Al2N3P: C, 68.03; H, 7.99; N, 7.93. Found: C, 67.79; H, 7.95; N,
7.63.
Preparation of Me3Al‚P(CH2NPh)3Al2Me3 (6b). A solution of
AlMe3 in toluene (5.0 mL, 2.0 M, 10.0 mmol) was added to a
solution of 1b (699 mg, 2.0 mmol) in 50 mL of toluene. The
solution was left for 48 h. The colorless solution was evaporated
to dryness, and the remaining solid was rinsed by pentane. The
white solid was collected by filtration and dried (558 mg, 54%).
X-ray-quality crystals were obtained from slow evaporation of a
77Se{1H} NMR (C6D6, 121.5 MHz, 298 K): δ -436.1 (d, JSeP
)
1
312.9 Hz.). Anal. Calcd for C27H49Al4N2PSe: C, 52.3; H, 7.97; N,
4.52. Found: C, 52.79; H, 7.68; N, 4.26.
pentane solution at -30 °C. H NMR (C6D6, 500 MHz, 298 K):
δ -0.68, -0.30, and -0.13 (s, 3H each, AlMe), -0.37 (s, 9H,
2
2
P-AlMe3), 3.22 (dd, 2H, JPH ) 4.8 Hz, JHH ) 4.8 Hz, PCH2),
Preparation of P[CH2N-3,5-(CF3)2C6H3]3Al2Me3 (5a). A solu-
tion of AlMe3 in toluene (3.09 mL, 2.0 M, 6.18 mmol) was added
to a solution of 1a (2.34 g, 3.09 mmol) in 15 mL of toluene. The
solution was left for 12 h. The solution was evaporated to dryness,
and the remaining solid was crystallized by cooling a saturated
warm benzene solution to room temperature. The tan solid was
collected by filtration and dried (1.5 g, 57%). A second crop was
obtained by slow evaporation of the mother liquor. X-ray-quality
crystals were obtained by slow evaporation of a benzene solution.
1H NMR (C6D6, 500 MHz, 298 K): δ -0.84 and -0.56 (s, 3H
2
2
3.70 (s, 2H, PCH2), 4.10 (dd, 2H, JPH ) 8.6 Hz, JHH ) 5.6 Hz,
PCH2), 6.9, 7.1, and 7.28 (m, Ph). 13C{1H} NMR (C6D6, 125.8
MHz, 298 K): δ -10.8, -9.0, and -8.5 (s, AlMe2), -8.0 (s,
P-AlMe3), 47.3 (d, JPC ) 10.3 Hz, PCH2), 52.7 (s, PCH2), 117.7,
119.7, 126.0, 126.8, 130.0, and 130.6 (s, Ph o-C, m-C, and p-C),
149.8 (d, J ) 3.7 Hz, ipso-C), 153.8 (d, J ) 6.2 Hz, ipso-C). 31P-
{1H} NMR (C6D6, 202.5 MHz, 298 K): δ -45.5 (s). Anal. Calcd
for C27H39Al3N3P: C, 62.66; H, 7.60; N, 8.12. Found: C, 62.17;
H, 6.95; N, 7.72.
2
each, AlMe2), -0.26 (s, 3H, AlMe), 2.70 (dd, 2H, JPH ) 1.3 Hz,
Preparation of Me3Al‚P(CH2N-3,5-Me2C6H3)3Al2Me3 (6c). A
solution of AlMe3 in toluene (2.0 mL, 2.0 M, 4.0 mmol) was added
to a solution of 1c (433.6 mg, 1 mmol) in 25 mL of toluene. The
solution was stirred at room temperature for 24 h. The solution
was evaporated to dryness, and the remaining solid was rinsed by
pentane. The white solid was collected by filtration and dried (367
2
2JHH ) 14.5 Hz, PCH2), 2.83 (d, 2H, JPH ) 6.8 Hz, PCH2), 3.56
2
2
(dd, 2H, JPH ) 16.9 Hz, JHH ) 14.4 Hz, PCH2), 7.30 (s, 2H,
p-H), 7.38 (s, 1H, p-H), 7.45 (s, 4H, o-H), 7.50 (s, 2H, o-H). 13C-
{1H} NMR (C6D6, 125.8 MHz, 298 K): δ -14.5, -5.6, and -1.4
(s, AlMe), -5.16 (s, AlMe), 44.8 (d, JPC ) 23.1 Hz, PCH2), 50.7
(d, JPC ) 15.1 Hz, PCH2), 121.1 and 123.4 (s, Ph o-C and m-C),
1
mg, 60%). H NMR (C6D6, 500 MHz, 298 K): δ -0.57, -0.25,

5602 Organometallics, Vol. 25, No. 23, 2006
Han and Johnson
and 0.01 (s, 3H each, AlMe), -0.38 (s, 9H, P-AlMe3), 2.00 (s,
Acknowledgment is made to the National Sciences and
Engineering Research Council (NSERC) of Canada and the
Ontario Research and Development Challenge Fund (ORDCF)
for their financial support.
2
12H, PhCH3), 2.27 (s, 6H, PhCH3), 3.45 (dd, 2H, JPH ) 9.5 Hz,
2
2JHH ) 5.1 Hz, PCH2), 3.87 (s, 2H, PCH2), 4.29 (dd, 2H, JPH
)
2
8.6 Hz, JHH ) 6.7 Hz, PCH2), 6.87 (s, 3H, Ph o-H), 7.00 (s, 6H,
Ph p-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ -14.2 and
-10.4 (s, AlMe2), -8.8 (s, P-AlMe3), -7.4 (s, AlMe), 21.5 (s,
PhCH3), 22.2 (s, PhCH3), 47.7 (d, JPC ) 12.7 Hz, PCH2), 52.8 (s,
PCH2), 116.3, 124.0, and 139.0 (s, Ph o-C, m-C, and p-C), 150.2
(d, J ) 6.3 Hz, ipso-C). 31P{1H} NMR (C6D6, 202.5 MHz, 298
K): δ -44.5 (s). Anal. Calcd for C33H51Al3N3P: C, 65.87; H, 8.54;
N, 6.98. Found: C, 65.52; H, 8.21; N, 7.34.
Supporting Information Available: Tables of crystallographic
data; crystallographic information in CIF format for 2a-c, 2b, 3a,
3c, 4b, 5a, and 6b. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM0607447