Main group compounds as amphoteric ligands to transition metals. Synthesis and molecular structure of Cr(CO)5[PPh2CH2Ga(CH2CMe 3)2·NMe3]

Article abstract of DOI:10.1021/om960547f

The reactivities of the group 13 compounds, R₂MCH₂PPh₂ and R₂MPPh₂, as amphoteric ligands to transition metals have been investigated. The ligands R₂MCH₂PPh₂ (R = CH₂-CMe₃, CH₂SiMe₃; M = Ga, In) reacted readily with Cr(CO)₅NMe₃ in benzene solution to form Cr(CO)₅[PPh₂CH₂MR₂·NMe ₃], whereas for ligands of the type R₂MPPh₂ (R = CH₂CMe₃, CH₂SiMe₃; M = Al, Ga, In), only the two aluminum compounds and (Me₃CCH₂)₂GaPPh2 formed isolable products of the type Cr(CO)₅[PPh₂MR₂·NMe₃]. However, the gallium and indium ligands with (trimethylsilyl)methyl substituents (Me₃SiCH₂)₂MPPh₂ reacted with NEt₄Mr(CO)₅Cl (M_T = Cr, Mo, W) to form products of the type NEt₄M_T(CO)₅[PPh₂MR₂Cl]. All new compounds were characterized by their physical properties, C and H analyses, and ¹H and ³¹P NMR and IR spectral properties. The identity of NEt₄Cr(CO)₅[PPh₂In(CH₂SiMe ₃)₂-Cl] was further confirmed by the subsequent identification of products from reactions with anhydrous HCl and with MeI. In addition, Cr(CO)₅[PPh₂CH₂Ga(CH₂CMe ₃)₂·NMe₃] was characterized by an X-ray structural study.

Full text of DOI:10.1021/om960547f

5170
Organometallics 1996, 15, 5170-5174
Ma in Gr ou p Com p ou n d s a s Am p h oter ic Liga n d s to
Tr a n sition Meta ls. Syn th esis a n d Molecu la r Str u ctu r e of
Cr (CO)5[P P h 2CH2Ga (CH2CMe3)2‚NMe3]
O. T. Beachley, J r.,*,† Michael A. Banks,† J ohn P. Kopasz,† and
Robin D. Rogers*,‡,§
Departments of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260,
and Northern Illinois University, DeKalb, Illinois 60115
Received J uly 8, 1996X
The reactivities of the group 13 compounds, R2MCH2PPh2 and R2MPPh2, as amphoteric
ligands to transition metals have been investigated. The ligands R2MCH2PPh2 (R ) CH2-
CMe3, CH2SiMe3; M ) Ga, In) reacted readily with Cr(CO)5NMe3 in benzene solution to
form Cr(CO)5[PPh2CH2MR2‚NMe3], whereas for ligands of the type R2MPPh2 (R ) CH2CMe3,
CH2SiMe3; M ) Al, Ga, In), only the two aluminum compounds and (Me3CCH2)2GaPPh2
formed isolable products of the type Cr(CO)5[PPh2MR2‚NMe3]. However, the gallium and
indium ligands with (trimethylsilyl)methyl substituents (Me3SiCH2)2MPPh2 reacted with
NEt4MT(CO)5Cl (MT ) Cr, Mo, W) to form products of the type NEt4MT(CO)5[PPh2MR2Cl].
All new compounds were characterized by their physical properties, C and H analyses, and
1H and 31P NMR and IR spectral properties. The identity of NEt4Cr(CO)5[PPh2In(CH2SiMe3)2-
Cl] was further confirmed by the subsequent identification of products from reactions with
anhydrous HCl and with MeI. In addition, Cr(CO)5[PPh2CH2Ga(CH2CMe3)2‚NMe3] was
characterized by an X-ray structural study.
Compounds of the type R2MER′2 (M ) group 13
were combined with Cr(CO)5NMe3 in benzene. How-
ever, only two of these compounds reacted to form the
isolable products, Cr(CO)5[PPh2Al(CH2CMe3)2‚NMe3]
and Cr(CO)5[PPh2Ga(CH2CMe3)2‚NMe3]. These two
element, E ) group 15 element) are amphoteric and
have the potential to be ligands to transition metals.
The goal of such a compound1 was realized when
Cr(CO)5[PPh2Al(CH2SiMe3)2‚NMe3] was prepared from
Cr(CO)5NMe3 and(Me3SiCH2)2AlPPh2 in benzene and
was fully characterized. The preparative reaction was
surprisingly slow at room temperature, as significant
quantities of product were not observed by NMR spec-
troscopy until after approximately 9 h of reaction time
had elapsed after 2 M solutions of reactants had been
combined. When the potential amphoteric ligand was
Et2AlPPh2, no transition metal derivative was formed.1
The difference in reactivity between the two amphoteric
ligands was attributed to their different degrees of
association in solution. The compound (Me3SiCH2)2-
AlPPh2 exists as a monomer-dimer equilibrium mix-
ture2 in benzene solution, whereas Et2AlPPh2 is a
dimer.2,3 As more examples of aluminum-, gallium-,
and indium-phosphorus derivatives with different de-
grees of association and with different types of bonding
are now available, additional reactions with Cr(CO)5-
NMe3 have been investigated. These main group am-
photeric compounds have also been reacted with NEt4MT-
(CO)5X (MT ) Cr, Mo,W; X ) Cl, Br) in benzene in order
to learn more about their reactivity patterns.
1/2[(Me3CCH2)2MPPh2]2 + Cr(CO)5NMe3 f
Cr(CO)5[PPh2M(CH2CMe3)2‚NMe3] (1)
(M ) Al, Ga)
new transition metal derivatives were characterized by
their physical properties, C and H analyses, and their
1H and 31P NMR and IR spectra. A comparison of the
spectral data for these new compounds with those
previously observed for Cr(CO)5[PPh2Al(CH2SiMe3)2‚-
NMe3], a compound which had been characterized by
X-ray crystallography,1 confirmed the identity of the
new products. It is noteworthy that, even though (Me3-
CCH2)2AlPPh2 exists as a dimer in benzene solution4
according to cryoscopic molecular weight studies, it is
significantly more reactive with Cr(CO)5NMe3 than is
(Me3SiCH2)2AlPPh2, a monomer-dimer equilibrium
mixture.2 Furthermore, (Me3CCH2)2GaPPh2 is also a
dimer5 and is reactive with Cr(CO)5NMe3, while (Me3-
SiCH2)2GaPPh2,5 (Me3CCH2)2InPPh2,5,6 and (Me3SiCH2)2-
6
InPPh2 are monomer-dimer equilibrium mixtures in
benzene solutions and are unreactive. These observa-
tions suggest that the Lewis acidity of the main group
moiety is more important than the degree of association.
The group 13 moiety apparently ties up the trimethy-
lamine so that the phosphorus can react with the
transition metal.
The potential ligands with the empirical formulas
(Me3CCH2)2AlPPh2,4 (Me3SiCH2)2GaPPh2,5 (Me3CCH2)2-
5,6
GaPPh2,5 (Me3SiCH2)2InPPh2,6 and (Me3CCH2)2InPPh2
† SUNY at Buffalo.
‡ Northern Illinois University.
§ Current address: Department of Chemistry, University of Ala-
bama, Tuscaloosa, AL 35487.
Another class of group 13-15 compounds which we
have previously prepared and fully characterized and
X Abstract published in Advance ACS Abstracts, November 1, 1996.
(1) Tessier-Youngs, C.; Bueno, C.; Beachley, O. T., J r.; Churchill,
M. R. Inorg. Chem. 1983, 22, 1054.
(4) Beachley, O. T., J r.; Victoriano, L. Organometallics 1988, 7, 63.
(5) Banks, M. A.; Beachley, O. T., J r.; Buttrey, L. A.; Churchill, M.
R.; Fettinger, J . C. Organometallics 1991, 10, 1901.
(2) Beachley, O. T., J r.; Tessier-Youngs, C. Organometallics 1983,
2, 796.
(3) J ohnson, A. W.; Larson, W. D.; Dahl, G. H. Can. J . Chem. 1963,
43, 1338.
(6) Beachley, O. T., J r.; Kopasz, J . P.; Zhang, H.; Hunter, W. E.;
Atwood, J . L. J . Organomet. Chem. 1987, 325, 69.
S0276-7333(96)00547-X CCC: $12.00 © 1996 American Chemical Society

Group 13 Amphoteric Ligands to Transition Metals
Organometallics, Vol. 15, No. 24, 1996 5171
Ta ble 1. Im p or ta n t In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) for
Cr (CO)5[P P h 2CH2Ga (CH2CMe3)2)‚NMe3]
(A) Bond Distances (Å)
atoms
Ga-N
distance
atoms
distance
2.235(3)
2.005(3)
2.409(1)
1.854(4)
1.903(4)
1.812(3)
1.835(3)
1.150(4)
1.137(4)
1.476(5)
1.462(5)
Ga-C(6)
Ga-C(24)
Cr-C(1)
Cr-C(3)
Cr-C(5)
P-C(7)
O(1)-C(1)
O(3)-C(3)
O(5)-C(5)
N-C(30)
2.027(3)
1.993(3)
1.889(4)
1.888(5)
1.843(4)
1.815(3)
1.134(4)
1.136(5)
1.147(4)
1.462(5)
Ga-C(19)
Cr-P
Cr-C(2)
Cr-C(4)
P-C(6)
P-C(13)
O(2)-C(2)
O(4)-C(4)
N-C(29)
N-C(31)
(B) Bond Angles (deg)
atoms
angle
atoms
angle
F igu r e 1. Molecular geometry of Cr(CO)5[PPh2CH2Ga-
(CH2CMe3)2‚NMe3]. ORTEP diagram for non-hydrogen
atoms and with hydrogen atoms omitted for clarity.
N-Ga-C(6)
95.1(1)
118.8(1)
115.2(1)
90.7(1)
88.3(2)
178.0(2)
93.5(1)
177.5(2)
175.9(1)
88.4(2)
Ga-C(6)-P
129.8(2)
120.3(3)
99.3(1)
100.4(1)
119.8(1)
87.5(1)
88.9(1)
89.7(2)
89.4(2)
92.7(2)
89.0(2)
91.4(2)
113.7(1)
106.8(2)
104.2(2)
112.2(2)
108.3(3)
108.3(3)
C(6)-Ga-C(19)
C(6)-Ga-C(24)
P-Cr-C(1)
P-C(7)-C(12)
N-Ga-C(19)
N-Ga-C(24)
C(19)-Ga-C(24)
P-Cr-C(2)
which can function as an amphoteric ligand to a
transition metal is R2MCH2PPh2. All four of the
compounds which were investigated (M ) Ga, In; R )
CH2CMe3, CH2SiMe3)7 reacted readily with Cr(CO)5-
NMe3 to form compounds of the type Cr(CO)5[PPh2CH2-
MR2‚NMe3]. Even though these potential ligands are
dimers in benzene solution, all were more reactive than
(Me3CCH2)2GaPPh2. For example, when [(Me3CCH2)2-
GaCH2PPh2]2 was combined with excess Cr(CO)5NMe3
in benzene at 20 °C, reaction was complete in 30 h,
whereas when the reactant was (Me3CCH2)2GaPPh2, the
C(1)-Cr-C(2)
C(1)-Cr-C(3)
P-Cr-C(4)
C(2)-Cr-C(4)
P-Cr-C(5)
C(2)-Cr-C(5)
C(4)-Cr-C(5)
Cr-P-C(7)
Cr-P-C(13)
C(7)-P-C(13)
Ga-N-C(30)
Ga-N-C(31)
C(30)-N-C(31)
Cr-C(2)-O(2)
Cr-C(4)-O(4)
P-Cr-C(3)
C(2)-Cr-C(3)
C(1)-Cr-C(4)
C(3)-Cr-C(4)
C(1)-Cr-C(5)
C(3)-Cr-C(5)
Cr-P-C(6)
90.6(2)
109.1(1)
118.6(1)
103.3(2)
110.5(2)
108.7(2)
108.7(3)
178.6(4)
176.8(4)
C(6)-P-C(7)
C(6)-P-C(13)
Ga-N-C(29)
C(29)-N-C(30)
C(29)-N-C(31)
1
ratio of product to reactant was estimated by H NMR
spectroscopy to be only 4.5:1 after 47 h. The general
trend for the reactivity of the R2MCH2PPh2 species
follows the relative Lewis acidity of the group 13 moiety,
with (Me3CCH2)2GaCH2PPh2 being the most reactive of
the four compounds studied, whereas (Me3SiCH2)2-
InCH2PPh2 was least reactive. There are two possible
reasons for the increased Lewis acidity and, in turn, the
increased reactivity of R2MCH2PPh2 in comparison with
that for R2MPPh2. The insertion of the methylene group
between the group 13 metal and phosphorus reduces
the steric bulk around both the Lewis acid and base sites
in the ligand and also eliminates any possibility for
π-bonding between the group 13 metal and phosphorus.
Ga(CH2CMe3)3‚NMe2C2H4NMe2‚Ga(CH2CMe3)3 (2.241-
(9) Å), but longer than the distances observed for other
trimethylgallium-amine adducts, 2.139(17) and 2.138-
(9) Å for the trimethylgallium-utropine adducts11 Me3-
Ga‚C6H12N4 and (Me3Ga)2‚C6H12N4, respectively, and
2.012(4) Å for Me3Ga‚NH2(t-Bu).12 Another noteworthy
feature of the structure of Cr(CO)5[PPh2CH2Ga(CH2-
CMe3)2‚NMe3] relates to the angular relationship be-
tween the three carbon atoms and the nitrogen atom
bonded to gallium. The two R-carbon atoms of the two
neopentyl groups and the methylene carbon atom
bonded to phosphorus have angles which are represen-
tative of distorted trigonal planar geometry rather than
tetrahedral, as C(6)-Ga-C(24) ) 115.2(1)°, C(6)-Ga-
C(19) ) 118.8(1)°, and C(19)-Ga-C(24) ) 119.8(1)°. The
carbon-gallium-nitrogen angles are, in turn, smaller
than the normal tetrahedral angle, with N-Ga-C(6)
) 95.1(1)°, N-Ga-C(19) ) 99.3(1)°, and N-Ga-C(24)
) 100.4(1)°. The angles between the six ligands around
chromium are typical of a slightly distorted octahedral
complex.
Recrystallization of Cr(CO)5[PPh2CH2Ga(CH2CMe3)2‚-
NMe3] from a saturated pentane solution at -25 °C
afforded crystallographic quality crystals. The crystal
consisted of discrete molecular units. There were no
abnormally close contacts in the unit cell. The labeling
of the atoms is given in Figure 1, and the significant
interatomic bond distances and angles are listed in
Table 1. The Cr-P bond distance is 2.409(1) Å, which
is shorter than the corresponding distances in Cr(CO)5-
[PPh2Al(CH2SiMe3)2‚NMe3]1 of 2.482(1) Å and in Cr(CO)5-
The reactions of (Me3SiCH2)2GaPPh2 and (Me3SiCH2)2-
InPPh2 with a different transition metal derivative,
NEt4MT(CO)5Cl (MT ) Cr, Mo, W), in benzene were also
investigated, and compounds of the type NEt4MT-
(CO)5[PPh2M(CH2SiMe3)2Cl] were readily formed. Each
8
PPh3 of 2.422(1) Å but longer than the distance in
Cr(CO)5[PPh2(CH2)4OAl(CH2SiMe3)2‚NMe3]9 of 2.383(6)
Å. The Ga-N distance of 2.235(3) Å is similar to that
observed for the trineopentylgallium-amine adduct,10
(7) Beachley, O. T., J r.; Banks, M. A.; Churchill, M. R.; Feighery,
W. G.; Fettinger, J . C. Organometallics 1991, 10, 3036.
(8) Plastas, H. J .; Stewart, J . M.; Grim, S. O. Inorg. Chem. 1973,
12, 265.
(9) Tessier-Youngs, C.; Youngs, W.; Beachley, O. T., J r.; Churchill,
M. R. Organometallics 1983, 2, 1128.
(10) Hallock, R. B.; Hunter, W. E.; Atwood, J . L.; Beachley, O. T.,
J r. Organometallics 1985, 3, 547.
(11) Krause, H.; Sille, K.; Hausen, H.-D.; Weidlein, J . J . Organomet.
Chem. 1982, 135, 253.
(12) Atwood, D. A.; J ones, R. A.; Cowley, A. H.; Bott, S. G.; Atwood,
J . L. J . Organomet. Chem. 1992, 434, 143.

5172 Organometallics, Vol. 15, No. 24, 1996
Beachley et al.
transition metal reactants were prepared according to litera-
ture methods. Solvents were dried according to conventional
procedures. Elemental analyses were performed by Schwarz-
of the reactions appeared to be complete within minutes
of mixing the reagents, as indicated by the disappear-
ance of the initially insoluble transition metal reagent.
Products were typically isolated as waxy solids or
viscous oils, with the exception of NEt4Cr(CO)5[PPh2-
In(CH2SiMe3)2Cl], which was obtained as a light yellow
crystalline powder in ∼80% yield. The formation of
NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl] is fully supported
1
kopf Microanalytical Laboratory, Woodside, NY. The H NMR
spectra were recorded at 400 MHz by using a Varian VXR-
400 spectrometer or at 90 MHz by using a Varian Model 390
spectrometer. Proton chemical shifts are reported in δ units
(ppm) and are referenced to SiMe4 at δ 0.00 and C6H6 at δ
7.15. The 31P NMR spectra were recorded at 161.9 MHz by
using either a Varian VXR-400 spectrometer or at 109.16 MHz
by using a J EOL Model FX 270 spectrometer. Chemical shifts
are referenced to 85% H3PO4 at δ 0.00. Standard abbrevia-
tions are used to report the multiplicities of the lines. All
samples for NMR spectra were contained in flame-sealed NMR
tubes. Infrared spectra were recorded as solutions by using
0.5 mm matched cells with NaCl windows or as Nujol mulls
between KBr plates with a Perkin-Elmer 683 spectrometer.
Absorption intensities are reported with standard abbrevia-
tions. Melting points were observed in sealed capillaries and
are uncorrected.
1
by C and H elemental analyses as well as by H, 31P,
and 13C NMR and IR spectral data. Further confirma-
tion of NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl] with a bond
between chromium and phosphorus was obtained by
investigating its reaction chemistry with HCl and MeI.
When NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl] was reacted
with anhydrous HCl in a 1:2 mole ratio, respectively,
the isolated products were Cr(CO)5PPh2H and SiMe4 (eq
2).
NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl] + 2HCl f
2SiMe4 + Cr(CO)5PPh2H + “NEt4InCl4” (2)
Syn th esis of Cr (CO)5[P P h 2Al(CH2CMe3)2‚NMe3]. A flask
equipped with Solv-Seal joints and a Teflon valve was charged
with 0.260 g (1.04 mmol) of Cr(CO)5NMe3,15 0.332 g (0.937
mmol) of (Me3CCH2)2AlPPh2, and 15 mL of benzene. The
resulting solution was initially yellow-orange and then light-
ened to pale yellow after being stirred for 48 h. The benzene
was then removed by vacuum distillation to leave a fluffy light
yellow solid. This solid was recrystallized from a 5:1 pentane/
benzene mixture to give 0.100 g (0.165 mmol, 17.6% yield
based on Cr(CO)5NMe3) of Cr(CO)5[PPh2Al(CH2CMe3)2‚NMe3]
The product Cr(CO)5PPh2H was formed in near
quantitative yield as based on 31P NMR spectral data
but was isolated in only 69% yield. The isolated sample
of Cr(CO)5PPh2H was identified by comparing its melt-
ing point and IR spectrum with the literature values.13
The SiMe4 was isolated in 82% yield and was identified
by its 1H NMR spectrum. No attempt was made to
isolate an indium-containing product. When NEt4Cr-
(CO)5[PPh2In(CH2SiMe3)2Cl] was reacted with MeI (eq
3), the only phosphorus-containing product was Cr-
1
as a yellow, crystalline solid: mp 116-117 °C dec; H NMR
(C6H6) δ 1.59 (s, 9H, NMe), 1.19 (s, 9H, CMe), 0.86 (s, 4H, CH2);
31P{1H} NMR (C6H6) δ -27.9 (s); IR (νCO, cm-1, Nujol mull)
2052 (m), 1980 (m), 1945 (m, sh), 1935 (vs), 1920 (s). Anal.
Calcd: C, 59.50; H, 6.82. Found: C, 59.43; H, 6.99. The
compound contained in a sealed vial under vacuum decom-
posed at room temperature over time (4 months).
NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl] + MeI f
Cr(CO)5PPh2Me + “NEt4In(CH2SiMe3)2(Cl)(I)” (3)
Syn th esis of Cr (CO)5[P P h 2Ga (CH2CMe3)2‚NMe3]. A 5
mm NMR tube was charged with 0.137 g (0.344 mmol) of (Me3-
CCH2)2GaPPh2 , 0.310 g (0.520 mmol) of Cr(CO)5NMe3, and
∼0.7 mL of benzene. After the mixture was warmed to
ambient temperature, an orange solution was present. The
1H and 31P{1H} NMR spectra were recorded prior to and after
heating the reaction mixture at 55 °C for 5 h. After 5 h at 55
°C, a yellow solution was present. Cooling of this solution to
(CO)5PPh2Me14 according to the 31P NMR spectrum of
the product mixture. However, the isolated product
which was thought to be Cr(CO)5PPh2Me was not pure.
The IR spectrum of the isolated product exhibited all
absorption bands expected for Cr(CO)5PPh2Me14 but
also had an extra band at 2035 cm-1, a band observed
in the IR spectrum of the starting compound, NEt4Cr-
(CO)5[PPh2In(CH2SiMe3)2Cl]. No attempt was made to
isolate and characterize an indium-containing product
from the reaction. It is noteworthy that a cryoscopic
molecular weight study of NEt4Cr(CO)5[PPh2In(CH2-
SiMe3)2Cl] in benzene suggested the existence of an
equilibrium between very highly associated species.
When the calculated concentration of the solution as
based on the empirical formula was 0.0990 m, the
observed degree of association was 5.99, whereas when
the solution was 0.0342 m, the association was 2.69.
These unusual degrees of association might serve to
provide an explanation for the very large, unsolvable
unit cell which was determined by the preliminary X-ray
structural study of the molecule.
ambient
temperature
afforded
yellow
crystals
of
Cr(CO)5[PPh2Ga(CH2CMe3)2‚NMe3]: mp 132-138 °C (glass
transition), 146-148 °C dec; IR (νCO, cm-1, pentane) 2063 (w),
1997 (vw), 1953 (vs), 1945 (s), 1917 (vw); initial NMR spectrum
1
prior to heating, H NMR (C6H6) δ 1.04 (s, 18H, CMe3), 1.22
3
(s, 0.7H), 1.33 (t, J PGaCH ) 3.6 Hz, 3.2H, CH2), 1.80 (s, 10H,
CrNMe3), 1.94 (s, 0.70H, GaNMe3), and 31P{1H} NMR (C6H6)
δ 30.7 (s, 1.0), -26.0 (s, 42.7, (Me3CCH2)2GaPPh2); 1 h, 40 min
1
at 55 °C, H NMR (C6H6) δ 1.06 (s, 2.4H, CH2), 1.13 (s, 18H),
1.22 (s), 1.72 (s, 7.9H, CrNMe3), 1.80 (s, 2.0H, GaNMe3), and
31P{1H} NMR (C6H6) δ 30.7 (s, 0.59), -18.3 (s, 15.8,
Cr(CO)5[PPh2Ga(CH2CMe3)2‚NMe3], -26.0 (s, 1.0, (Me3CCH2)2-
GaPPh2 ) [Additional 31P NMR resonances of very low intensity
at 0.5, 27.9, 30.7, 33.2 and 43.3 ppm were observed but could
not be identified. The ratio of the intensity of the most intense
line at 30.7 ppm relative to the lines at -18.3 and -26.0 ppm
was 1.00:1.7:26.9, respectively.]; 5 h at 55 °C, 1H NMR (C6H6)
δ 1.05 (s, 2.1H, CH2), 1.13 (s, 18H), 1.23 (s), 1.70 (s, 7.8H,
CrNMe3), 1.80 (s, 2.5H, GaNMe3), and 31P{1H} NMR (C6H6) δ
30.7 (s, 0.04), -18.3 (s, 22.8, Cr(CO)5[PPh2Ga(CH2CMe3)2‚-
NMe3]) [The low-intensity resonances at 0.5, 27.9, 30.7, 33.2,
and 43.3 ppm were still present but with little change in
intensity from the previous spectrum.].
Exp er im en ta l Section
All of the compounds which contain group 13 elements were
extremely sensitive to oxygen and moisture and were manipu-
lated in a standard vacuum line or in a purified argon
atmosphere. All starting group 13-15 compounds and all
Syn th esis of Cr (CO)5[P P h 2CH2Ga (CH2CMe3)2‚NMe3].
A flask equipped with a Teflon valve was charged with 0.576
(13) Smith, J . G.; Thompson, D. T. J . Chem. Soc. A 1967, 1694.
(14) Grim, S. D.; Wheatland, D. A.; McFarlane, W. J . J . Am. Chem.
Soc. 1967, 89, 5573.
(15) Wasserman, H. J .; Wovkulich, M. J .; Atwood, J . D.; Churchill,
M. R. Inorg. Chem. 1980, 19, 2831.

Group 13 Amphoteric Ligands to Transition Metals
Organometallics, Vol. 15, No. 24, 1996 5173
Ta ble 2. Cr ysta l Da ta a n d Su m m a r y of In ten sity
Da ta Collection a n d Str u ctu r e Refin em en t for
Cr (CO)5[P P h 2CH2Ga (CH2CMe3)2‚NMe3]
g (1.26 mmol) of (Me3CCH2)2GaCH2PPh2, 0.456 g (1.82 mmol)
of Cr(CO)5NMe3, and 15 mL of benzene. The initial mixture,
an orange solution with a colorless precipitate, was heated at
60 °C with stirring for 3.5 h to form a clear yellow solution.
The benzene was removed by vacuum distillation to leave a
light-yellow oil. This oil was heated at 60 °C for 15 h with
continuous evacuation and then 30 mL pentane was added by
vacuum distillation. The resulting light yellow solution was
stirred for ∼30 min, and the pentane was removed by vacuum
distillation and discarded. This procedure of adding and
removing pentane was repeated 3 times until a pale yellow
solid with only a trace of oil remained. Evacuation for another
18 h was followed by the addition of 45 mL of pentane and
heating with a warm water bath. The resulting mixture was
filtered with a coarse frit to remove a colorless precipitate and
leave a yellow solution. Cooling of the solution to -25 °C
afforded pale yellow crystals of Cr(CO)5[PPh2CH2Ga(CH2-
CMe3)2‚NMe3] (0.330 g, 0.498 mmol, 39.4% yield based on (Me3-
CCH2)2GaCH2PPh2). These crystals were suitable for the
molecular formula
color/shape
MW
CrGaPNC31H43O5
yellow/irregular
662.4
crystal system
space group
temp, °C
a, Å
triclinic
P1h
20
10.768(8)
b, Å
10.875(8)
c, Å
15.155(8)
R, deg
90.65(5)
104.66(6)
90.38(6)
1716.8
â, deg
γ, deg
V, Å3
Z
D
µ
2
1.28
11.2
calc, cm-1
calc, cm-1
diffractometer/scan
Enraf-Nonius Cad4/θ - 2θ
range of relative transm factors, % 88/100
1
X-ray structural study: mp 95.0-96.5 °C; H NMR (C6H6) δ
radiation, graphite monochromator Mo KR (λ ) 0.710 73)
0.55 (s, 4H, -CH2-), 0.96 (s, 18H, CMe3), 1.58 (s, 6H, NMe3),
1.71 (s, 2H, -CH2P-); 31P{1H} NMR (C6H6) δ 48.2 (s); IR
(pentane, νCO, cm-1) 2060 (s), 1989 (sh), 1980 (s), 1969 (vs),
1956 (sh). Anal. Calcd: C, 56.21; H, 6.54; P, 4.68. Found:
C, 55.87; H, 6.72; P, 4.99.
max. crystal dimensions, mm
reflections measured
2θ range, deg
0.30 × 0.40 × 0.55
6002
2 e 2θ e 50
+12,(12,(18
4638
range of h,k,l
reflections observed [Fo g 5σ(Fo)]
computer programs
structure solution
SHELX17
MULTAN18
0.038
Syn th esis of Cr (CO)5[P P h 2CH2In (CH2CMe3)2‚NMe3].
The synthesis of the compound was achieved by using 0.536 g
(1.10 mmol) of (Me3CCH2)2InCH2PPh2, 0.439g (1.75 mmol) of
Cr(CO)5NMe3, and 20 mL of benzene and the procedure
described for the previous compound. Pale yellow crystals of
Cr(CO)5[PPh2CH2In(CH2CMe3)2‚NMe3] (0.156g, 0.211 mmol,
19.2% based on (Me3CCH2)2InCH2PPh2) were obtained upon
cooling a saturated pentane solution to -30 °C: mp 120-122
°C; 1H NMR (C6H6) δ 0.64 (s, 4H, -CH2-), 1.03 (s, 18H,
-CMe3), 1.43 (d, J ) 4.5 Hz, 2H, -CH2P-), 1.68 (s, 9H, NMe3)
[In addition, there were low-intensity lines at 0.86 and 1.26
ppm which are consistent with a pentane impurity, but these
R ) ∑||Fo| - |Fc||/∑|Fo|
Rw
0.039
largest feature final diff map
0.5 e- Å-3
Least-squares refinement with isothermal parameters led
to R ) 0.095. The phenyl and methylene hydrogen atoms were
placed in calculated positions 0.95 Å from the bonded carbon
atoms and allowed to ride on that atom, with B fixed at 5.5
Å2. The methyl hydrogen atoms were located from a difference
Fourier map and included with fixed contributions (B ) 5.5
Å2). Refinement of the non-hydrogen atoms with anisotropic
temperature factors led to final values of R ) 0.038 and Rw
0.039.
Syn th esis of NEt4Cr (CO)5[P P h 2In (CH2SiMe3)2Cl].
lines were not conclusively identified.]; IR (pentane, νCO, cm-1
)
)
2058 (m), 1990 (w), 1980 (w), 1955 (sh), 1943 (vs), 1935 (vs),
1870 (w, br). Anal. Calcd: C, 52.63; H, 6.13. Found: C, 52.24;
H, 5.43.
A
flask was charged with 0.530 g (1.12 mmol) of (Me3SiCH2)2-
InPPh2 and 0.400 g (1.12 mmol) of NEt4Cr(CO)5Cl.16-18 After
30 mL of benzene was transferred to the flask by vacuum
distillation, the contents were warmed to room temperature,
and a light yellow solution formed within approximately 10
min. The mixture was stirred for 12 h, and then the benzene
was removed by vacuum distillation to leave a material which
was a mixture of a light yellow oil and light yellow solid. This
material was washed 4 times with 20 mL of pentane. After
the pentane was removed by vacuum distillation, the product
was evacuated for 1 h to give a light yellow solid, 0.755 g (0.907
mmol, 80.9% yield) of NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl]: mp
102-105 °C (glass), 110-120 °C (becomes translucent), 140-
160 °C dec (yellow to red glass); cryoscopic molecular weight,
fw 832 (obsd molality, obsd mol wt, association): 0.0165, 4983,
5.99; 0.0142, 3652, 4.39; 0.0130, 2904, 3.49; 0.0177, 3536, 4.25;
Rea ction of R2MCH2P P h 2 w ith Cr (CO)5NMe3 (M ) Ga ,
R ) CH2CMe3, CH2SiMe3; M ) In , R ) CH2SiMe3) As
Mon itor ed by 31P NMR Sp ectr oscop y. All reactions were
carried out in 10 mm NMR tubes using the following proce-
dure. Weighed quantities of reactants were added to the tube,
and then ∼1.9 mL of benzene was added by vacuum distilla-
tion. The tube was sealed by fusion, and the 31P NMR
spectrum recorded after the sample was held at room tem-
perature for the time indicated.
(Me3CCH2)2GaCH2PPh2 (0.0402 g, 0.0907 mmol), Cr(CO)5-
NMe3 (0.0260 g, 0.104 mmol): 20 min, -10.2 (s, (Me3CCH2)2-
GaCH2PPh2); 38 h, -10.1 (s, 4.6, (Me3CCH2)2GaCH2PPh2), 48.1
(s, 1.0, Cr(CO)5[PPh2CH2Ga(CH2CMe3)2‚NMe3].
(Me3SiCH2)2GaCH2PPh2 (0.0509 g, 0.118 mmol), Cr(CO)5-
NMe3 (0.0297 g, 0.118 mmol): 37 h, -10.2 (s, 4.7, (Me3SiCH2)2-
GaCH2PPh2), 46.3 (s, 1.0, Cr(CO)5[PPh2CH2Ga(CH2SiMe3)2‚
NMe3]).
1
0.0140, 2796, 3.36; 0.0127, 2238, 2.69; H NMR (C6H6) δ 2.15
(q, 8H, NCH2), 0.44 (t, 12H, NCH2CH3), 0.36 (s, 18H, SiCH3),
0.13 (t, 4H, InCH2); 13C NMR (C6H6) δ 226.14 (d, J ) 7 Hz,
trans-CO), 220.21 (d, J ) 8.8 Hz, cis-CO), 54.01 (t, NCH2CH3),
8.66 (s, NCH2CH3), 4.61 (s, SiCH3), InCH2 not observed; 31P
NMR (C6H6) δ -18.3 (s); IR (νCO, THF solution) 2065 (w), 2050
(m), 2035 (w, sh, impurity), 1937 (s, sh), 1927 (vs), 1890 (m,
sh). Anal. Calcd: C, 47.63; H, 6.30. Found: C, 47.53; H, 6.33.
Rea ction of NEt4Cr (CO)5[P P h 2In (CH2SiMe3)2Cl] w ith
MeI. A 100 mL flask was charged with 0.555 g (0.667 mmol)
(Me3SiCH2)2InCH2PPh2 (0.0596 g, 0.122 mmol), Cr(CO)5-
NMe3 (0.0319 g, 0.127 mmol): 38 h, -9.8 (s, 8.1, (Me3SiCH2)2-
InCH2PPh2), 47.5 (s, 1.0, Cr(CO)5[PPh2CH2In(CH2SiMe3)2‚-
NMe3]).
X-r a y Da ta Collection , Str u ctu r e Deter m in a tion , a n d
Refin em en t for Cr (CO)5[P P h 2CH2Ga (CH2CMe3)2‚NMe3].
A yellow fragment of a single crystal of the title compound
was mounted under argon in a thin-walled glass capillary and
transferred to the goniometer. The space group was deter-
mined to be either the centric P1h or acentric P1. The
subsequent solution and successful refinement of the structure
were carried out in the centric space group P1h. A summary
of data collection parameters is given in Table 2.
(16) Abel, W. E.; Butler, I. S.; Reid, J . G. J . Chem. Soc. 1963, 2068.
(17) Sheldrick, G. M., SHELX76, a system of computer programs
for X-ray structure determination as locally modified. Cambridge
University, 1976.
(18) Germain, G.; Main, P.; Woolfson, M. M. Acta Crystallogr. 1971,
A27, 368.

5174 Organometallics, Vol. 15, No. 24, 1996
Beachley et al.
of NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl], and then excess MeI
(15 mL) was added by vacuum distillation. The resulting
solution was stirred for 2.5 h at room temperature, and then
all volatile components were removed by vacuum distillation
to leave a sticky, yellow solid. The sticky nature of this solid
made it impossible to weigh the product. Thus, the solid was
dissolved in benzene for spectroscopic characterization; 31P
NMR δ 36.0 (lit.14 Cr(CO)5PPh2Me, 31P NMR δ 35.0 ppm); IR
(ν, cm-1, THF) 2064 (m), 2035 (w), 1980 (w), 1947 (s, sh), 1940
(vs) 1885 (w) (lit.14 Cr(CO)5PPh2Me IR (ν, cm-1, THF) 2064
(s), 1981 (vw), 1947 (sh), 1939 (vs)).
Rea ction of NEt4Cr (CO)5[P P h 2In (CH2SiMe3)2Cl] w ith
HCl. A flask was charged with 0.833 g (1.00 mmol) of NEt4-
Cr(CO)5[PPh2In(CH2SiMe3)2Cl] and 25 mL of benzene. An-
hydrous HCl (2.04 mmol) was then condensed into the flask
by using a liquid N2 bath. The flask was warmed to room
temperature, and the resulting solution was stirred for 0.5 h.
The SiMe4 was separated by fractionation through two -78
°C traps and collected in a -196 °C trap. The amount of SiMe4
was calculated from PVT measurements (1.64 mmol, 82%
based on NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl]). The remaining
solid was extracted 8 times with 20 mL of pentane to give 0.260
g of Cr(CO)5PPh2H (0.687 mmol, 68.7% based on NEt4-
Cr(CO)5[PPh2In(CH2SiMe3)2Cl]): mp 56-59 °C (lit.13 55-65
°C); IR (ν, cm-1, Nujol mull) 2330 (w), 2060 (s), 1982 (m), 1907
(s) (lit.13 IR (ν, cm-1, Nujol mull) 2325 (w), 2068 (m), 1979 (m),
1937 (vs), 1900 (sh)).
Syn th esis of NEt4MT(CO)5[P P h 2M(CH2SiMe3)2Cl] (MT
) Cr , Mo, W; M ) Ga ; MT ) Mo, W; M ) In ). All compounds
were prepared according to the following procedure. A flask
was charged with 1.0 mmol of the transition metal carbonyl
chloride, 1.0 mmol of the main group metal phosphide and 15
mL of benzene. A clear solution formed approximately 10 min
after the benzene was added to the reactants. After the
solution was stirred for 24 h, the benzene was removed by
vacuum distillation to leave a thick viscous oil or waxy solid
which was resistant to crystallization. Some purification was
achieved by dissolving the product in 20 mL of benzene and
then adding 10 mL of pentane. This mixture was stirred for
1 h and then allowed to settle into two layers, a dark brown
lower layer and a light yellow upper layer. The light yellow
upper layer was removed in the drybox by using a syringe,
whereas the brown lower layer was discarded without further
study. The solvent was removed by vacuum distillation to
leave a viscous oil, which turned into a sticky, waxy yellow
material after continuous evacuation for 12 h. This product
was characterized by IR and 31P NMR spectroscopy. The
sticky nature of the products precluded a reliable estimate of
mass and percent yield. Attempts to purify these compounds
by thin-layer or column chromatography resulted in apparent
hydrolysis with formation of MT(CO)5PPh2H13 (MT ) Cr, Mo,
W).
NEt4MT(CO)5[PPh2M(CH2SiMe3)2Cl] (MT, M). Cr, Ga: 31P
NMR δ -14.9; IR (ν, cm-1, C6H6) 2060 (w), 2042 (w), 1940 (m),
1920 (vs), 1890 (s); IR (ν, cm-1, THF) 2060 (w), 2040 (w), 1940
(m), 1925 (vs), 1905 (s), 1895 (s, sh). Mo, Ga: 31P NMR δ
-25.8; IR (ν, cm-1, THF) 2075 (w), 2057 (m), 1950 (m, sh), 1930
(vs), 1893 (s). W, Ga: 31P NMR δ -42.4 (J W-P ) 156 Hz); IR
(ν, cm-1, THF) 2070 (w), 2058 (m), 1940 (vs), 1925 (s, sh), 1908
(s), 1870 (m, sh). Mo, In: 31P NMR δ -31.3; IR (ν, cm-1, THF)
2075 (w), 2060 (m), 1950 (m, sh), 1932 (vs), 1895 (m). In, W:
31P NMR δ -49.0 (J W-P ) 166 Hz); IR (ν, cm-1, THF) 2070
(w), 2058 (m), 1940 (m, sh), 1920 (vs), 1890 (m).
Ack n ow led gm en t. This work was supported in part
by the Office of Naval Research (O.T.B.). The extensive
efforts by Professor Melvyn R. Churchill to determine
the structure of NEt4Cr(CO)5[PPh2In(CH2SiMe3)2Cl] by
X-ray crystallography were greatly appreciated.
Su p p or tin g In for m a tion Ava ila ble: Complete tables of
positional parameters, interatomic distances and angles,
anisotropic thermal parameters, and calculated positions for
hydrogen atoms (5 pages). Ordering information is given on
any current masthead page.
OM960547F