P-P bond activation of P4 tetrahedron by group 13 carbenoid and its bis molybdenum pentacarbonyl adduct

Article abstract of DOI:10.1021/ic1010743

Activation of white phosphorus with Ga(DDP) (DDP = 2-diiso- propylphenylamino-4-diiso-propylphenylimino-2-pentene) afforded [(DDP)Ga(P ₄)] (1) by insertion of the Ga(I) center at one of the six P-P bonded edges of the P₄ tetrahedron. Further reaction of 1 with three equivalents of Mo(CO)₆ results in the formation of [(DDP)Ga(η^2:1:1-P₄){Mo(CO)₅}₂] 2toluene (2). Compounds 1 and 2 are characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, elemental analysis, and single crystal X-ray structural analysis. The solid-state structure of molecule 1 reveals the first example of a structurally characterized GaP₄ core stabilized by a β-diketiminate ligand. Compound 2 represents a rare type of coordination mode of a gallium supported P₄ butterfly structure.

Full text of DOI:10.1021/ic1010743

7976 Inorg. Chem. 2010, 49, 7976–7980
DOI: 10.1021/ic1010743
P-P Bond Activation of P4 Tetrahedron by Group 13 Carbenoid and its Bis
Molybdenum Pentacarbonyl Adduct
Ganesan Prabusankar, Adinarayana Doddi, Christian Gemel, Manuela Winter, and Roland A. Fischer*
Chair of Inorganic Chemistry-II, Organometallics and Materials Chemistry Laboratory, Ruhr-University
Bochum, D-44780 Bochum, Germany
Received May 27, 2010
Activation of white phosphorus with Ga(DDP) (DDP = 2-diiso-propylphenylamino-4-diiso-propylphenylimino-2-pentene)
afforded [(DDP)Ga(P4)] (1) by insertion of the Ga(I) center at one of the six P-P bonded edges of the P4 tetrahedron.
Further reaction of 1 with three equivalents of Mo(CO)6 results in the formation of [(DDP)Ga(η2:1:1-P4){Mo-
(CO)5}2] 2toluene (2). Compounds 1 and 2 are characterized by 1H, 13C, and 31P NMR spectroscopy, elemental
3
analysis, and single crystal X-ray structural analysis. The solid-state structure of molecule 1 reveals the first example of
a structurally characterized GaP4 core stabilized by a β-diketiminate ligand. Compound 2 represents a rare type of
coordination mode of a gallium supported P4 butterfly structure.
Introduction
group metals.2-10 The main group metal mediated P-P bond
activation of the P4 tetrahedron can be classified as either
activation or insertion of the P4 core by main group
elements.3-10
The interest in selective activation of a P-P bond in highly
reactive white phosphorus is deeply rooted in phosphorus
chemistry.1 Especially transition metal-mediated P-P bond
activation has a promising future to produce phosphorus
transfer reagents for organic reactions, while this type of
reaction is still at an early stage of development with main
Fragmentation reactions are the most common pathways
of P4 with main group precursors. Recently G. Bertrand et al.
have documented the fragmentation of P4 by a N-hetero-
cyclic carbene (NHC) and related carbene ligands.3b-d
A
similar type of reaction is observed with σ-donor low-valent
main group elements. For example, the reaction between P4
and (DDP)Al (DDP = 2-diiso-propylphenylamino-4-diiso-
propylphenylimino-2-pentene) resulted in the formation
of [{(DDP)Al}2P4] (A) by the attack of two P-P bonds
leading to double insertion.4 Interestingly, the series of re-
lated carbenoid ER reactants, i.e., [Cp*Al]4 (Cp* = C5Me5),
[{(Me3Si)3C}Ga]4 and [ArTl]2 (Ar = C6H3(2,6-iPr2-C6H3)2)
afford [(Cp*Al)6P4] (B),5 [{(Me3Si)3CGa}3P4] (C),6 and
[(ArP)2P2Tl2] (D),7 respectively, by dissipation of the P4
tetrahedron (Chart 1). It is most often difficult to predict the
fate of P4 inthese reactions, and random distribution of metal
centers in the phosphorus core is observed.
*Corresponding author. E-mail: roland.fischer@rub.de. Telephone:
þ4923432-24174.
(1) (a) Corbridge, D. E. C. Phosphorus - An Outline of its Chemistry,
Biochemistry and Technology, 5th ed., Elsevier, Amsterdam, 1995. (b) Emsley, J.
The 13th Element: The Sordid Tale of Murder, Fire, and Phosphorus, Wiley,
New York, 2002.
(2) (a) Peruzzini, M.; Gonsalvi, L.; Romerosa, A. Chem. Soc. Rev. 2005,
34, 1038–1047. (b) Ehses, M.; Romerosa, A.; Peruzzini, M. Top. Curr. Chem.
2002, 220, 107–140. (c) Fox, A. R.; Clough, C. R.; Piro, N. A.; Cummins, C. C.
Angew. Chem., Int. Ed. 2007, 46, 973–976. (d) Figueroa, J. S.; Cummins, C. C.
Dalton Trans. 2006, 2161–2168. (e) Piro, N. A.; Figueroa, J. S.; McKellar, J. T.;
Cummins, C. C. Science 2006, 313, 1276–1279. (f) Cummins, C. C. Angew.
Chem., Int. Ed. 2006, 45, 862–870. (g) Cossairt, B. M.; Piro, N. A.; Cummins,
C. C. Chem. Rev. 2010, 110, 4164–4177. (h) Figueroa, J. S.; Cummins, C. C.
Dalton Trans. 2006, 2161–2168. (i) Cummins, C. C. Angew. Chem., Int. Ed.
€
2006, 45, 862–870. (j) Scherer, O. J.; Swarowsky, M.; Wolmershauser, G.
Organometallics 1989, 8, 841–842. (k) Caporali, M.; Gonsalvi, L.; Rossin, A.;
Peruzzini, M. Chem. Rev. 2010, 110, 4178–4235.
(8) Power, M. B.; Barron, A. R. Angew. Chem., Int. Ed. 1991, 30, 1353–
1354.
(9) For examples: (a) Chan, W. T. K.; Garcıa, F.; Hopkins, A. D.; Martin,
L. C.; McPartlin, M.; Wright, D. S. Angew. Chem., Int. Ed. 2007, 46, 3084–
3086. (b) Lerner, H.-W.; Bolte, M.; Karaghiosoff, K.; Wagner, M. Organome-
(3) Holthausen, M. H.; Weigand, J. J. J. Am. Chem. Soc. 2009, 131,
14210–14211. (b) Masuda, J. D.; Schoeller, W. W.; Donnadieu, B.; Bertrand, G.
J. Am. Chem. Soc. 2007, 129, 14180–14181. (c) Lynam, J. M. Angew. Chem.,
Int. Ed. 2008, 47, 831–833. (d) Back, O.; Kuchenbeiser, G.; Donnadieu, B.;
Bertrand, G. Angew. Chem., Int. Ed. 2009, 48, 5530–5533.
€
tallics 2004, 23, 6073–6076. (c) Wiberg, N.; Worner, A.; Karaghiosoff, K.;
Fenske, D. Chem. Ber. 1997, 130, 135–140. (d) Lerner, H.-W.; Wagner, M.;
Bolte, M. Chem. Commun. 2003, 990–991. (e) Lerner, H.-W.; Margraf, G.;
Kaufmann, L.; Bats, J. W.; Wagner, M.; Bolte, M. Eur. J. Inorg. Chem. 2005,
(4) Peng, Y.; Fan, H.; Zhu, H.; Roesky, H. W.; Magull, J.; Hughes, C. E.
Angew. Chem., Int. Ed. 2004, 43, 3443–3445.
€
(5) Dohmeier, C; Schnockel, H.; Robl, C; Schneider, U; Ahlrichs, R.
€
€
1932–1939. (f) Wiberg, N.; Worner, A.; Lerner, H.-W.; Karaghiosoff, K.; Noth, H.
Z. Naturforsch., B: J. Chem. Sci. 1998, 53, 1004–1014.
(10) Xiong, Y.; Yao, S.; Brym, M.; Driess, M. Angew. Chem., Int. Ed.
2007, 46, 4511–4513.
Angew. Chem., Int. Ed. 1994, 33, 199–200.
(6) Uhl, W.; Benter, M. Chem. Commun. 2000, 771–772.
(7) Fox, A. R.; Wright, R. J.; Rivard, E.; Power, P. P. Angew. Chem., Int.
Ed. 2005, 44, 7729–7733.
r
pubs.acs.org/IC
Published on Web 08/12/2010
2010 American Chemical Society

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7977
Chart 1. Molecular Species Obtained from the Reaction of Monova-
in the cooled nitrogen stream of the diffractometer. The crystal-
lographic data and details of the final R values are provided in
Supporting Information (Table S1). The structural solution and
refinement were performed using the programs SHELXS-97
and SHELXL-97.12a,b Molecules 1 and 2 were refined with
distance restraints and restraints for the anisotropic displace-
ment parameters. The disordered solvent molecule toluene in 2
was “squeezed” out with the program Platon 1.13.12c
lent Group 13 Ligandsa
Synthesis of 1. Toluene (1.5 mL) was added to a Schlenk tube
charged with Ga(DDP) (0.1 g, 0.209 mmol) and P4 (0.026 g,
0.209 mmol) at room temperature under vigorous stirring.
Slowly the P4 was consumed within 30 min, and the reaction
mixture color changed from yellow to orange. The clear orange
solution was stirred for 24 h, volatiles were removed under
vacuum, and the yellow-orange solid was dissolved in n-hexane/
toluene mixture (2:1) under warm condition, filtered, and stored
at -30 °C to afford bright yellow crystals of 1. Yield: 83% (0.106
g, based on P4). Mp: 232-234 °C. 1H NMR (C6D6, 250 MHz), δ:
7.17-7.04 (m, 6H, Ar CH), 4.58 (s, 1H, γ-CH), 3.19 (sept, 4H,
CH(Me)2), 1.42 (s, 12H, CH3), 1.49 (d), 0.94 (d) (24H, CH(Me)2)
ppm. 13C NMR (C6D6, 62.8952 MHz), δ: 168.6 (C(Dipp)-N),
144.0 (CMe), 140.3 [o-C(Dipp)], 129.3 [p-C(Dipp)], 125.0
[m-C(Dipp)], 96.1 (γ-C), 29.4 (CHMe2), 25.3 (CHMe2), 25.2
(CMe), 23.7 (CHMe2) ppm. 31P NMR (C6D6, 101.2545 MHz),
δ: -328.7 (1JPP = 152 Hz, 2P, P-P), 212.7 (1JPP = 152 Hz, 2P,
Ga-P) ppm. Anal. calcd (%) for C43H57GaN2P4 (795.56): C,
64.92; H, 7.22; N, 3.52. Found: C, 64.89; H, 7.17; N, 3.50.
Synthesis of 2. To a mixture of Mo(CO)6 (0.129 g, 0.490
mmol) and 1 (0.1 g, 0.163 mmol), dry toluene (4 mL) was added,
stirred for 5 min, and heated at 80 °C for 1day. The resultant
brown solution was evaporated in order to remove all volatiles.
The brown residue was then redissolved in toluene (5 mL),
layered with n-hexane and placed at -30 °C for 1day to give pale
yellow crystals of compound 2. The crystals were washed with
n-hexane (2 ꢀ 4 mL) and dried under vacuum. Yield (0.070 g,
41%, based on [(DDP)Ga(P4)]. Decomp. range >160 °C. IR (ν,
cm-1): 2966(w), 2929(w), 2871(w), 2064(s), 1995(w), 1934(vs),
1912(vs), 1888(vs), 1588(m), 1437(w), 1312(w), 1254(w), 1019(w),
871(w), 799(m), 789(m), 758(w), 600(vs), 581(vs), 559(w), 532(w),
442(w). 1H NMR (toluene-d8, 250 MHz), δ: 7.19-6.99 (m,
6H, Ar CH), 4.50 (s, 1H, γ-CH), 3.09 (sept, 4H, CH(Me)2),
1.64 (d, 12H, CH(Me)2), 1.37 (s, 6H, CH3), 1.07 (d, 12H,
CH(Me)2) ppm. 13C NMR (toluene-d8, 62.8952 MHz), δ:
204.8 (Mo-CO), 170.55 (C(Dipp)-N), 143.7 (CMe), 138.7
[o-C(Dipp)], 137.9 [p-C(Dipp)], 128.2 [m-C(Dipp), overlapped
with solvent resonances], 98.3 (γ-CH), 29.5 (CHMe2), 26.5
(CHMe2), 24.8 (CMe), 23.8 (CHMe2) ppm. 31P NMR (C6D6,
101.2545 MHz), δ: -315.2 (1JPP = 174 Hz, 2P, P-P), 51.6
(1JPP = 175 Hz, 2P, Ga-P) ppm. Anal. calcd (%) for C53H57-
N2O10GaP4Mo2 (1267.53): C, 50.22; H, 4.53; N, 2.21. Found C,
51.09; H, 4.99; N, 2.43.
a RE(I) [R; bulky organic group, E: Al, Ga, Tl] with white phosphorus.
Interestingly, the P4 molecule also shows addition reac-
tions with Lewis acids, such as tBu3Ga,8 or dissipation
reactions with strong bases, such as tBu3SiNa and [(Me3Si)3-
SiK][18-crown-6].9 However, stable molecules with single
insertion of low-valent main group elements at P4 core are
limited, and such types of molecules can provide four naked
phosphorus centers for further reactions. The only reported
example with a low-valent main group metal is a P4 unit
supported by the NHC analog DDP00Si [DDP00 = HC-
(CMeNC6H3-2,6-iPr2)(H2CdCNC6H3-2,6-iPr2)].10 Hereby
we report the synthesis, spectroscopic, and structural char-
acterization of the first example of a tetraphosphabicyclobu-
tane molecule [(DDP)Ga(P4)] (1) which is supported by a
group 13 metal center and its bis-molybdenum pentacarbo-
nyl adduct [(DDP)Ga(η2:1:1-P4){Mo(CO)5}2] 2toluene (2).
3
Experimental Section
General Procedures. All manipulations were carried out in an
atmosphere of purified argon using standard Schlenk and
glovebox techniques. Hexane and toluene were dried using an
MBraun solvent purification system. The final H2O content in
all solvents was checked by Karl Fischer titration and did not
exceed 5 ppm. Ga(DDP) was prepared as previously described
procedure.11 Unless otherwise stated, chemicals used in this
work were purchased from commercial sources. Elemental
analyses were performed by the Microanalytical Laboratory
€
of the Ruhr-Universitat Bochum. NMR spectra were recorded
on a Bruker Avance DPX-250 spectrometer in C6D6 or toluene-
d8 at 25 °C. Chemical shifts are given relative to tetramethylsi-
lane (TMS) and were referenced to the solvent resonances as
internal standards. Chemical shifts are described in parts per
million, downfield shifted from TMS, and are consecutively
reported as position (δH or δC), relative integral, multiplicity
(s = singlet, d = doublet, sept = septet, m = multiplet), coupling
constant (J in Hz), and assignment. IR measurement (neat) was
carried out on a Bruker Alpha-P Fourier transform spectrometer.
X-ray Crystallography. Crystals of 1 and 2 were obtained
from mixtures of toluene/n-hexane at -30 °C. X-ray data for
compounds 1 and 2 were collected on an Oxford Excalibur 2
diffractometer. The crystals were coated with a perfluoropo-
lyether, picked up with a glass fiber, and immediately mounted
Results and Discussion
The activation of P4 using gallium reagents was first
investigated by A. R. Barron et al. in 1991. The tBu and
gallium addition of tBu3Ga into P4 led to the isolation of
[tBu2Ga{(P)(PtBu)(PGatBu)(P)}].8 In contrast, the three-
fold insertion of gallium into the P-P bond of P4 was
observed when 3/4 [{(Me3Si)3C}Ga]4 was treated with P4.6
However, a single or double insertion of a gallium center into
P4 has not been reported yet. Since the sterically encumbered
Ga(DDP) is knownto stabilizetheunusualZintl-type cluster,
(12) (a) Sheldrick, G. M. SHELXS-97, Program for the Solution of Crystal
€
€
€
StructuresUniversitat Gottingen: Gottingen, Germany, 1997. (b) Sheldrick, G. M.
€
€
SHELXL-97, Program for Crystal Structure RefinementUniversitat Gottingen:
€
(11) Hardman, N. J.; Eichler, B. E.; Power, P. P. Chem. Commun. 2000,
1991–1992.
Gottingen, Germany, 1997. (c) Spek, A. L. Acta Crystallogr., Sect. A: Found.
Crystallogr. 1990, 46, C34.

7978 Inorganic Chemistry, Vol. 49, No. 17, 2010
Scheme 1. Synthesis of 1 and 2
Prabusankar et al.
Figure 1. Molecular structure of 1 (50% ellipsoids). The H atoms
˚
attached to carbon are omitted for clarity. Important bond lengths (A)
and angles (°): Ga(1)-N(2) 1.907(6), Ga(1)-N(1) 1.968(6), Ga(1)-P(3)
2.340(2), Ga(1)-P(1) 2.346(2), P(2)-P(4) 2.154(3), P(2)-P(3) 2.239(3),
P(2)-P(1) 2.242(3), P(3)-P(4) 2.245(3), P(4)-P(1) 2.229(3), P(3)-P(2)-
P(1) 90.14(11), P(4)-P(2)-P(1) 60.88(10), P(2)-P(3)-P(4) 57.41(10),
P(2)-P(4)-P(1) 61.53(10), P(2)-P(4)-P(3) 61.15(10), P(1)-P(4)-P(3)
90.34(11), P(4)-P(1)-P(2) 57.60(10), P(4)-P(2)-P(3) 61.44(10), P(2)-
P(3)-Ga(1) 83.38(9), N(2)-Ga(1)-N(1) 97.1(3), N(2)-Ga(1)-P(3)
119.03(19), N(1)-Ga(1)-P(3) 119.71(17), N(2)-Ga(1)-P(1) 115.82(18),
N(1)-Ga(1)-P(1) 122.03(18), P(3)-Ga(1)-P(1) 85.21(8), P(4)-P(3)-
Ga(1) 85.11(9), P(2)-P(1)-Ga(1) 83.17(9), P(4)-P(1)-Ga(1) 85.34(9).
[{(DDP)Ga(Cl)}4(Sn17)]13 and dibismuthenes, [{(DDP)Ga-
(ORf)}(Bi)]2 (Rf = SO2CF3, C6F5),14 we anticipated a mild
reaction between Ga(DDP) and P4.
Synthesis and Structural Characterization of 1. Reac-
tion of P4 with one equivalent of Ga(DDP)11 in toluene at
room temperature resulted in the formation of 1 (Scheme 1).
Bright yellow crystals of 1 were obtained in a good yield
(83%) when a solution of the crude product in a mixture
of toluene and n-hexane was cooled from room tempera-
ture to -30 °C and stored at this temperature for 12 h. It is
highly soluble in common organic solvents, such as
benzene, toluene, and THF. Moreover, it is stable both
in solution as well as in the solid state at room tem-
perature in an inert atmosphere (Ar). Molecule 1 has been
Molecule 1 crystallizes in the tetragonal space group,
P43212 (Figure 1). Compound 1 can be regarded as a
single insertion product of (DDP)Ga into one of the P-P
bonds of a P4 tetrahedron. Therefore, the molecular struc-
ture of 1 is comparable with that of [(DDP00)Si(P4)].10 The
tetraphosphabicyclobutane fragment in 1 shows a typical
butterfly shape structure. Atoms Ga(1), P(1), and P(3) are
in the same plane, while the atoms P(2), P(4), and the six-
membered GaN2C3 ring are perpendicular to the former
plane. The Ga-P bond distances in 1 are almost equal
within the range of the accuracy to the measured data:
1
characterized by H, 13C, and 31P NMR spectroscopy,
elemental analysis, and single crystal X-ray structural
˚
˚
2.346(2) A for Ga(1)-P(1) and 2.340(2) A for Ga(1)-P(3).
Consequently, the remaining five P-P bond distances are
1
analysis. The H and 13C NMR spectra of 1 exhibit the
expected resonances for a DDP ligand, well comparable
with known metal complexes of Ga(DDP). The 31P NMR
spectrum shows two triplets at δ þ212.7 and -328.7 ppm.
The signal at δ þ212.7 ppm with a large coupling constant
(1JPP = 152 Hz) can be assigned to the phosphorus atoms
linked to the gallium center. The same coupling constant
is also observed for the remaining two phosphorus atoms
with a upfield chemical shift value at δ -328.7 ppm. The
chemical shift value for P-Ga is nearly δ 47-95 ppm
downfield shifted, while that for P-P-Ga is δ 110-122
ppm upfield shifted compared to [(Cp00)2M(P4)] (Cp00 =
η5-1,3-tBu2-C5H3) [M = Zr (δ þ166.1 and -206.5 ppm),
Hf (δ þ117.5 and -219.3 ppm)].15 Moreover, a consider-
able downfield shift of P-Ga (δ 80 ppm) and P-P-Ga (δ
16 ppm) in 1 is observed compared to [(DDP00)Si(P4)],
which is well acceptable since the electron delocaliza-
tion in C3N2Si and C3N2Ga backbones are distinctly
different.10
˚
different and fall within the range of 2.154(3)-2.245(3) A.
Although such types of bonding features were reported for
˚
[Cp*(CO)Co(P4)] (Co-P = 2.261(1) and 2.255(1) A;
2j
00
˚
P-P range = 2.158(2)-2.217(2) A) and [(DDP )Si(P4)]
˚
(Si-P = 2.250(1) and 2.246(1) A; P-P range = 2.159(2)-
2.235(2) A),10 compound 1 draws near to the higher end of
˚
the P-P bond distances. The P(2)-P(4) bond distance in 1
˚
is approximately 0.056(3)A shorter than that of the P-P
˚
bond distance found in P4 (2.21(2) A), while P(2)-P(3)
˚
˚
˚
(0.029 A), P(2)-P(1) (0.032 A), P(3)-P(4) (0.035 A), and
P(4)-P(1) (0.019 A), are slightly elongated.16 The P(1) and
˚
˚
P(3) separation in 1 is 3.173(3) A, which is somewhat larger
than that of [Cp*(CO)Co(P4)]2j (P P=2.606(1) A) and
˚
3 3 3
11
[(DDP00)Si(P4)] (P P = 3.103 A). Furthermore, the
˚
3 3 3
value of the angle P(1)-Ga(1)-P(3) is 85.21(8)o, which
compares with P-Si-P angle (87.32(5)o) of [(DDP00)-
Si(P4)].11 The widening of the P-P-P angles reveals the
distorted tetrahedral geometry for the phosphorus cen-
ters. The sum of P-P-P angle around P(2) (Σ P(2)=
212.46(10)o) and P(4) (Σ P(4) = 213.02(10)o) and the sum
of Ga-P-P and P-P-P angle around P(1) (Σ P(1) =
226.11(9)o) and P(3) (Σ P(3) = 225.9(9)o) are comparable.
€
(13) Prabusankar, G.; Kempter, A.; Gemel, C.; Schroter, M.-K.; Fischer,
R. A. Angew. Chem., Int. Ed. 2008, 47, 7234–7237.
(14) Prabusankar, G.; Gemel, C.; Parameswaran, P.; Flener, C.; Frenking,
G.; Fischer, R. A. Angew. Chem., Int. Ed. 2009, 48, 5526–5529.
€
(15) Scherer, O. J.; Swarowsky, M.; Swarowsky, H.; Wolmershauser, G.
Angew. Chem., Int. Ed. 1988, 27, 694–695.
(16) Corbridge, D. E. C.; Lowe, E. J. Nature 1952, 170, 629.

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7979
The P(2)-P(3)-P(4) bond in the P4 core exhibits the lowest
P-P-P angle (57.41(10)o), while the P(1)-P(4)-P(3)
depicts the highest angle (90.34(11)o).
The shortening of the Ga-N bond (Ga(1)-N(2)
˚
1.907(6) and Ga(1)-N(1) 1.968(6) A) and elongation of
N(1)-Ga-N(2) angle (97.1(3)o) in 1, as compared to free
˚
Ga(DDP) (av. Ga-N = 2.0544 A; N-Ga-N = 87.53°),
demonstrates the increased electrophilic nature of Ga-
(DDP) upon coordination to the P4 moiety.11 As shown in
the space-filling representation of 1 (Supporting Infor-
mation, Figure S4), the sterically crowded DDP group
effectively protects the extremely reactive P4 moiety of 1
and thereby prevents its oligomerization.
Synthesis and Structural Characterization of 2. Further-
more, the coordinating ability of 1 was investigated with
hexacarbonylmolybdenum. Compound 2 was prepared
from a mixture of [Mo(CO)6] and 1 in a ratio of approxi-
mately 3:1 in toluene at 80 °C. Elimination of one
carbonyl group in [Mo(CO)6] led to the formation of 2.
Pale yellow crystals of 2 are soluble in polar organic
solvents and stable at room temperature. Compound 2
is an air- and moisture-sensitive compound and stable
only under inert atmosphere. It has been characterized by
elemental analysis, IR, multinuclear NMR (1H, 13C, and
31P), and single crystal X-ray diffraction techniques. As
indicated by elemental analysis, 2 has the composition of
Figure 2. Molecular structure of 2 (50% ellipsoids). The H atoms
attached to carbon and toluene molecules are omitted for clarity. Im-
portant bond lengths (A) and angles (°): Mo(2)-P(1) 2.5458(8), P(4)-
˚
Mo(1) 2.5856(8), Ga(1)-P(1) 2.3746(8), Ga(1)-P(4) 2.4051(8), Ga(1)-
N(2) 1.927(2), Ga(1)-N(1) 1.931(2), P(4)-P(3) 2.2163(11), P(4)-P(2)
2.2195(11), P(3)-P(2) 2.1818(11), P(3)-P(1) 2.2174(11), P(2)-P(1)
2.2244(11), N(2)-Ga(1)-N(1) 98.71(10), P(1)-Ga(1)-P(4) 79.03(3),
P(3)-P(4)-P(2) 58.93(4), P(3)-P(4)-Ga(1) 88.73(3), P(2)-P(4)-Ga-
(1) 88.12(3), P(3)-P(4)-Mo(1) 107.06(4), P(2)-P(4)-Mo(1) 107.85(4),
Ga(1)-P(4)-Mo(1) 161.66(3), P(2)-P(3)-P(4) 60.61(4), P(2)-P(3)-
P(1) 60.74(3), P(4)-P(3)-P(1) 86.62(4), P(3)-P(2)-P(4) 60.47(4), P(3)-
P(2)-P(1) 60.42(3), P(4)-P(2)-P(1) 86.38(4), P(3)-P(1)-P(2) 58.84(4),
P(3)-P(1)-Ga(1) 89.48(3), P(2)-P(1)-Ga(1) 88.77(3), P(3)-P(1)-Mo(2)
115.73(4), P(2)-P(1)-Mo(2) 116.61(4), Ga(1)-P(1)-Mo(2) 150.59(3).
[(DDP)Ga(P4){Mo(CO)5}2] 2toluene (2) and is suffi-
3
ciently pure to be used directly for further characteriza-
tion. IR spectroscopy confirms the presence of five
attached to the phosphorus atoms of 1 in monodendate
(η1) fashion. Interestingly, each Mo(CO)5 fragment is
tethered to the phosphorus atoms that are linked to the
gallium center, which is a rather rare type of coordina-
tion mode observed for metal complexes bearing a tetra-
phosphorus ligand.2,17b,18 However, the reaction of
DDP00Si with [(NiDDP)2 toluene] or [(NiDDP0)2 toluene]
carbonyl bands (νCO 2064(s), 1995(w), 1934(vs), 1912(vs),
h
1888(vs) cm-1), all attributable to the Mo(CO)5 frag-
ment.17 The 13C NMR spectrum of 2 in toluene-d8 shows
only one peak in the carbonyl region (δ 204.8 ppm) (see
Supporting Information, Figure S6 and references there).
The 31P NMR spectrum of 2 in C6D6 displays two triplets
at δ -315.2 and 51.6 ppm. The triplet at δ -315.2 ppm
corresponds to the uncoordinated phosphorus atoms,
which is slightly shifted downfield with respect to 1 (Δδ
13.5 ppm). The lower field triplet at δ 51.6 ppm can be
attributed to the phosphorus atoms of [P-Mo(CO)5]
moiety, and upon coordination, a very strong upfield
shift (Δδ 161.1 ppm) is observed. Although compound 2
is isolated exclusively from this reaction, the 31P NMR
spectrum of the mother liquor clearly indicates the pre-
sence of more than one complex with different coordina-
tion modes (Supporting Information).
3
3
(DDP0 = 2-di-ethylphenylamino-4-diethylphenylimino-
2-pentene) results in molecules consisting of a [Si(μ,η2:2
-
P4)Ni] core similar to 2.19 The molybdenum center in 2
is in distorted octahedral geometry, surrounded by five
CO ligands and one P atom. Interestingly, the Mo(CO)5
fragment prefers coordination at the more nucleophilic P
centers (as suggested by VB formulas of the P42- anion),
despite the sterically less favorable situation at this
positions.
˚
The Mo-P bond lengths (Mo(2)-P(1), 2.5458(8) A and
˚
Mo(1)-P(4), 2.5856(8) A) in 2 are not equal, and it is com-
parable with [Cp0Mo(CO)2(η3-P4){Cr(CO)5}4(H)] (Cp0 =
The molecular structure of 2 is shown in Figure 2.
Compound 2 crystallized from toluene/n-hexane mixture
in the monoclinic space group P21/n (Figure 2) with two
solvent molecules of toluene per asymmetric unit. Com-
pound 2 consists of a Ga, Mo, and P based heteronuclear
[Ga(η2:1:1-P4)Mo2] core. Two Mo(CO)5 fragments are
C5H4tBu).17b The Ga(1)-P(1) distance (2.3746(8) A) is
˚
˚
distinctly shorter than that of Ga(1)-P(4) (2.4051(8) A).
˚
The average Ga-P bond distances (2.3899(8) A) in 2
are slightly longer than the same bond distances of 1
˚
(2.343(2) A). As shown in Figure S9 (Supporting Infor-
mation), a negligible elongation of P-P bond lengths with
respect to 1 (except P(2)-P(3)) is observed. The P-P bond
::
€
(17) (a) Senturka, O. S.; Serta, S.; Ozdemir, U. Z. Naturforsch. 2003, 58b,
˚
distance of 2 falls in the range of 2.1818(11)-2.2244(11) A.
1124–1127. (b) Scheer, M.; Becker, U.; Magull, J. Polyhedron 1998, 17, 1983–
1989.
The P(1)-Ga(1)-P(4) bond angle is 79.03(3)o, which is
nearly 6° lower than 1 (P(1)-Ga(1)-P(3), 85.21(8)o). As
expected, a slight change in the bond angle of GaP4 core is
observed in 2 as compared to 1. The central GaN2C3 ring
atoms of Ga(DDP) are essentially coplanar.
(18) For examples:(a) Scheer, M.; Troitzsch, C.; Jones, P. G. Angew.
Chem., Int. Ed. 1992, 31, 1377–1379. (b) Akbayeva, D. N. Russ. J. Coord.
Chem. 2006, 32, 329–334. (c) Akbayeva, D. N.; Scherer, O. J. Z. Anorg. Allg.
Chem. 2001, 627, 1429–1430. (d) Scheer, M.; Becker, U.; Matern, E. Chem. Ber.
1996, 129, 721–124. (e) Scheer, M.; Dargatz, M. J. Organomet. Chem. 1992,
440, 327–333. (f) Akbayeva, D. N. Russ. J. Coord. Chem. 2007, 33, 661–668.
(g) Scheer, M.; Becker, U. J. Organomet. Chem. 1997, 545-546, 451–460.
(h) Scheer, M.; Troitzsch, C.; Hilfert, L.; Dargatz, M.; Kleinpeter, E.; Jones, P. G.;
Sieler, J. Chem. Ber. 1995, 128, 251–257.
(19) Xiong, Y.; Yao, S.; Bill, E.; Driess, M. Inorg. Chem. 2009, 48, 7522–
7524.

7980 Inorganic Chemistry, Vol. 49, No. 17, 2010
Prabusankar et al.
Conclusions
heteronuclear [Ga(η2:1:1-P4)Mo2] core, which is an example
of a rare coordination mode observed in metal supported P4
molecules.
In summary, the activation of a single P-P bond in white
phosphorus (P4) by Ga(DDP) (DDP=2-diiso-propylpheny-
lamino-4-diiso-propylphenylimino-2-pentene) led to the iso-
lation of molecular gallium-tetraphosphabicyclopentane (1)
with open access to the phosphorus core. The butterfly shape
P4 unit coordinated to the Ga(DDP) framework is the first
example of a single insertion of a monovalent group 13
element at the P4 tetrahedron. Further reaction of [(DDP)-
Ga(P4)] with excess of Mo(CO)6 afforded 2 consisting of a
Acknowledgment. G.P. is grateful for a stipend by the
Alexander von Humboldt Foundation.
Supporting Information Available: Figures S1-S9, Table S1,
and CIF files. This material is available free of charge via the
Internet at http://pubs.acs.org.