Facile access to a stable divalent Germanium compound with a terminal PH2 group and related PR2 derivatives

Article abstract of DOI:10.1021/om800269f

The first stable β-diketiminate germanium(II) complexes LGeY [L = CH{(CMe)(2,6-ⁱPr₂C₆H₃N)} ₂] with terminal phosphanyl groups Y (Y = PH₂, PHR, and PR₂) are described. Thus, LGePH₂ (2) is synthesized by salt metathesis reaction of LGeCl (1) with lithium phosphanide and can be isolated in the form of orange crystals in 83% yield. Its silylation with 1 molar equiv of Me₃SiOTf (OTf = OSO₂CF₃) in the presence of triethylamine as auxiliary base leads solely to LGeP(H)SiMe3 (3). In contrast, reaction of 2 with 2 molar equiv of Me₃SiOTf does not lead to the desired product LGeP(SiMe₃)₂ (4), but LGeOTf (6) and HP(SiMe₃)₂ are formed. However, compound 4 is conveniently accessible from 1 and the corresponding lithium phosphanide LiP(SiMe₃)₂. While attempts to metalate the PH₂ group in 2 applying BuLi and M₂Zn, respectively, lead merely to Ge-P fission and undesired side products, its conversion with ^tBu ₂Hg occurs without Ge-P fission but P-P bond formation to give the novel P,P′-bis(phosphanylgermylene) LGeP(H)-P(H)GeL (5), elemental mercury, and isobutane. Compounds 2-6 have been fully characterized, including elemental analyses, NMR spectroscopy, and single-crystal X-ray diffraction analysis.

Full text of DOI:10.1021/om800269f

Organometallics 2008, 27, 3601–3607
3601
Facile Access to a Stable Divalent Germanium Compound with a
Terminal PH2 Group and Related PR2 Derivatives
Shenglai Yao,† Markus Brym,† Klaus Merz,‡ and Matthias Driess*,†
Technische UniVersita¨t Berlin, Institute of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2,
Strasse des 17. Juni 135, D-10623 Berlin, Germany, and Faculty of Chemistry, Ruhr-UniVersita¨t Bochum,
UniVersita¨tsstrasse 150, D-44801 Bochum, Germany
ReceiVed March 27, 2008
The first stable ꢀ-diketiminate germanium(II) complexes LGeY [L ) CH{(CMe)(2,6-iPr2C6H3N)}2]
with terminal phosphanyl groups Y (Y ) PH2, PHR, and PR2) are described. Thus, LGePH2 (2) is
synthesized by salt metathesis reaction of LGeCl (1) with lithium phosphanide and can be isolated in the
form of orange crystals in 83% yield. Its silylation with 1 molar equiv of Me3SiOTf (OTf ) OSO2CF3)
in the presence of triethylamine as auxiliary base leads solely to LGeP(H)SiMe3 (3). In contrast, reaction
of 2 with 2 molar equiv of Me3SiOTf does not lead to the desired product LGeP(SiMe3)2 (4), but LGeOTf
(6) and HP(SiMe3)2 are formed. However, compound 4 is conveniently accessible from 1 and the
corresponding lithium phosphanide LiP(SiMe3)2. While attempts to metalate the PH2 group in 2 applying
BuLi and Me2Zn, respectively, lead merely to Ge-P fission and undesired side products, its conversion
with tBu2Hg occurs without Ge-P fission but P-P bond formation to give the novel P,P′-
bis(phosphanylgermylene) LGeP(H)-P(H)GeL (5), elemental mercury, and isobutane. Compounds 2-6
have been fully characterized, including elemental analyses, NMR spectroscopy, and single-crystal X-ray
diffraction analysis.
Scheme 1
Introduction
Due to their carbene-like properties, molecular divalent
germanium species (germylenes) have attracted much attention
in the past decades. Since the seminal work by Lappert et al.
on the synthesis of isolable germylenes in 1976,1 remarkable
progress has been made in the preparation and application of
stable Ge(II) compounds in coordination chemistry.2 This has
been achieved by judicious choice of sterically demanding
substituents on the Ge(II) atom, which provide a kinetic and
thermodynamic stabilization with π-donor groups bonded to the
divalent germanium atom. Taking advantage of the intramo-
lecular stabilization of coordination of nitrogen to low-valent
germanium, a number of stable ꢀ-diketiminate germanium(II)
complexes LGeX A (Scheme 1; L ) ꢀ-diketiminate; X ) halide,
alkyl, hydride, hydroxide, alkoxide, and amide) have been
synthesized,3,4 among which LGeH,3g LGeCH3,3e and LGeOH3f
deserve particular attention because of the small terminal groups
and their remarkable electronic features. Recently, Power et al.
described the first germanium(II) amide with the parent NH2
group, which was obtained by reacting a corresponding terphe-
nyl germanium(II) halide with liquid ammonia.5 To our
knowledge, a stable divalent germanium species featuring the
parent phosphanide group PH2 is unknown as yet, although a
few bulky phosphanyl-substituted germylenes have been re-
ported.6
Currently, we are particularly interested in structure-reactivity
relationships of N-heterocyclic divalent group 14 element
* Corresponding author. E-mail: matthias.driess@tu-berlin.de.
† Technische Universita¨t Berlin.
(3) (a) Ayers, A. E.; Klapo¨tke, T.; Dias, H. V. R. Inorg. Chem. 2001,
40, 1000. (b) Akkari, A.; Byrne, J. J.; Saur, I.; Rima, G.; Gornitzka, H.;
Barrau, J. J. Organomet. Chem. 2001, 622, 190. (c) Ding, Y.; Roesky, H. W.;
Noltemeyer, M.; Schmidt, H. G.; Power, P. P. Organometallics 2001, 20,
1190. (d) Ding, Y.; Hao, H.; Roesky, H. W.; Noltemeyer, M.; Schmidt,
H.-G. Organometallics 2001, 20, 4806. (e) Ding, Y.; Ma, Q.; Roesky, H. W.;
Herbst-Irmer, R.; Uso´n, I.; Noltemeyer, M.; Schmidt, H.-G. Organometallics
2002, 21, 5216. (f) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Neculai, D.;
Neculai, A. M. Angew. Chem., Int. Ed. 2004, 43, 1419. (g) Pineda, L. W.;
Jancik, V.; Starke, K.; Oswald, R. B.; Roesky, H. W. Angew. Chem., Int.
Ed. 2006, 45, 2602. (h) Saur, I.; Alonso, S. G.; Barrau, J. Appl. Organomet.
Chem. 2005, 19, 414.
‡ Ruhr-Universiat Bochum.
(1) (a) Harris, D. H.; Lappert, M. F.; Pedley, J. B.; Sharp, G. J. J. Chem.
Soc., Dalton Trans. 1976, 945. (b) Davidson, P. J.; Harris, D. H.; Lappert,
M. F. J. Chem. Soc., Dalton Trans. 1976, 2268.
(2) Reviews: (a) Barrau, J.; Escudie´, J.; Satge´, J. Chem. ReV 1990, 90,
283. (b) Weidenbruch, M. Eur. J. Inorg. Chem. 1999, 373. (c) Klinkhammer,
K. W. Recent advances in structural chemistry of organic germanium, tin
and lead compounds. In The Chemistry of Organic Germanium, Tin and
Lead Compounds, Vol. 2; Rappoport,Z. , Ed.;Wiley: NewYork, 2002;
Chapter 4, pp 284-332. (d) Ku¨hl, O. Coord. Chem. ReV. 2004, 248, 411.
(e) Jutzi, P.; Keitemeyer, S.; Neumann, B.; Stammler, H.-G. Organometallics
1999, 18, 4778. (f) Driess, M.; Dona, N.; Merz, K. Dalton Trans. 2004,
3176. (g) Tokitoh, N.; Okazaki, R. Coord. Chem. ReV. 2000, 210, 251. (h)
Weidenbruch, M. J. Organomet. Chem. 2002, 646, 39. (i) Barrau, J.; Rima,
G. Coord. Chem. ReV. 1998, 178, 593.
(4) Stender, M.; Phillips, A. D.; Power, P. P. Inorg. Chem. 2001, 40,
5314.
(5) Stanciu, C.; Hino, S. S.; Stender, M.; Richards, A. F.; Olmstead,
M. M.; Power, P. P. Inorg. Chem. 2005, 44, 2774.
10.1021/om800269f CCC: $40.75
2008 American Chemical Society
Publication on Web 06/25/2008

3602 Organometallics, Vol. 27, No. 14, 2008
Yao et al.
Scheme 2
complexes LEX (E ) Si, Ge, Sn, and Pb; L ) N-heterocyclic,
monoanionic chelate ligands; X ) alkoxide, amide, halide,
phosphanide), which could serve as single-site initiators for the
polymerization of lactides or/and Lewis acid catalysts for ring-
opening polymerization.7Using the sterically encumbering
ꢀ-diketiminate ligand, we have successfully synthesized a series
of heteroleptic ꢀ-diketiminato complexes of lead(II) bearing
terminal phenolato, bis(trimethylsilyl)amido, bis(trimethylsi-
lyl)phosphanido, and silylidenephosphanido ligands.8 Further-
more, we prepared the first silicon(II) analogues L(Si:)R′ (R′
) siloxyl,9 OTf,10 B(C6F5)4),11 applying the zwitterionic silylene
L′Si: (L′
) CH[(CdCH2)CMe][N(aryl)]2; aryl ) 2,6-
iPr2C6H3).10 Interestingly, dark brown crystals of the Ge(II)
homologue of the latter silylene, compound B (Scheme 1),12
are also conveniently accessible through dehydrochlorination
of LGeCl (1)3c with LiN(SiMe3)2. Furthermore, the betain-like
germylene B reacts with 1,2-dibromoethane, affording the
bis(bromogermylene) C(Scheme 1) as yellow crystals.12 Here
we report the synthesis and characterization of the first series
of stable ꢀ-diketiminate germanium(II)-phosphanido complexes
LGePH2 (2), LGeP(H)SiMe3 (3), LGeP(SiMe3)2 (4), and
LGeP(H)P(H)GeL (5) (L ) ꢀ-diketiminate).
Results and Discussion
Synthesis. The ꢀ-diketiminato-substituted chlorogermylene
LGeCl (1)3c readily reacts with 1 molar equiv of [LiPH2 (dme)]
(dme ) 1,2-dimethoxyethane) in diethyl ether at -50 °C to
give a clear orange solution. The NMR spectroscopic data of
the reaction mixture indicate that the desired phosphanyl-
substituted germanium complex LGePH2 (2) is formed nearly
quantitatively after warming to room temperature and stirring
overnight (Scheme 2). After extraction with n-hexane, com-
pound 2 can be obtained in the form of orange crystals in 83%
yield. Its composition and constitution are proven by elemental
has been isolated in the form of orange-brown cubes in 77%
yield through extraction with n-hexane and recrystallization at
-20 °C. Unexpectedly, attempts to prepare LGeP(SiMe3)2 (4)
by further silylation of the phosphorus in 3 with trimethylsilyl
triflate failed. Instead, the reaction of 3 with 1 molar equiv of
trimethylsilyl triflate leads merely to LGeOTf (6) and
HP(SiMe3)2. Although the mechanism is still unknown, we
believe that the latter products result from degradation of the
corresponding phosphonium triflate ion pair [LGeP(H-
)(SiMe3)2]+ OTf- as reactive intermediate. In line with that,
the ease of Ge-P fission and replacement of HP(SiMe3)2 by
the relatively weak OTf- nucleophile reduces steric congestion
and leads to the partially resonance stabilized LGe+ cation4 in
the contact ion pair 6.
1
analysis and H, 13C, and 31P NMR spectroscopy. In addition,
the structure of 2 has been confirmed by single-crystal X-ray
diffraction analysis (see below). While compound 2 is sensitive
to oxygen and moisture, it is indefinitely stable under nitrogen
atmosphere and survives prolonged heating of solutions even
at 110 °C for several hours.
Fortunately, compound 4 is accessible from salt metathesis
reaction of 1 with the corresponding lithium phosphanide
[LiP(SiMe3)2(dme)] (Scheme 2) and obtained in the form of
pale yellow crystals in 89% yield. It is noteworthy that the
reaction of 1 with the nitrogen analogue LiN(SiMe3)2 leads
solely to the zwitterionic germylene B by dehydrochlorination
instead of a nucleophilic Cl/N(SiMe3)2 substitution at germa-
nium.12 Apparently, the P(SiMe3)2 anion is not strong enough
to act as a corresponding base, and the voluntary Ge-P bond
formation reflects the higher polarizability and nucleophilicity
of phosphorus in contrast to nitrogen.
Compound 2 represents the first stable ꢀ-diketiminate ger-
manium(II) complex with the parent phosphanide PH2 group.
Accordingly, it could serve as a convenient building block for
other phosphane derivatives. This has been shown by simple
silylation of the phosphorus atom. In fact, reaction of 2 with 1
molar equiv of trimethylsilyl triflate, Me3SiOTf, in the presence
of triethylamine as auxiliary base in diethyl ether at -60 °C
leads merely to LGeP(H)SiMe3 (3) (Scheme 2). Compound 3
(6) (a) du Mont, W.-W.; Schumann, H. Angew. Chem., Int. Ed. Engl.
1975, 14, 368. (b) Druckerbrodt, C.; du Mont, W.-W.; Ruthe, F.; Jones,
P. G. Z. Anorg. Allg. Chem. 1998, 624, 590. (c) Driess, M.; Janoschek, R.;
Pritzkow, H.; Rell, S.; Winkler, U. Angew. Chem., Int. Ed. Engl. 1995, 34,
1614. (d) Izod, K.; McFarlane, W.; Allen, B.; Clegg, W.; Harrington, R. W.
Organometallics 2005, 24, 2157.
(7) Dove, A. P.; Gibson, V. C.; Marshall, E. L.; Rzepa, H. S.; White,
A. J. P.; Williams, D. J. J. Am. Chem. Soc. 2006, 128, 9834.
(8) Yao, S.; Block, S.; Brym, M.; Driess, M. Chem. Commun. 2007,
3844.
(9) Yao, S.; Brym, M.; van Wu¨llen, C.; Driess, M. Angew. Chem., Int.
Ed. 2007, 46, 4659.
(10) Driess, M.; Yao, S.; Brym, M.; van Wu¨llen, C.; Lentz, D. J. Am.
Chem. Soc. 2006, 128, 9628.
In order to prepare isolable heterobimetallic phosphanido
complexes of Ge(II), we investigated the reactivity of 2 toward
potential metalation reagents. However, attempts to metalate
the terminal PH2 group in 2 applying BuLi and Me2Zn,
respectively, failed and led only to nucleophilic replacement of
the PH2 group and irrepressible side reactions. Interestingly, the
preferential Ge-P fission in 2 through attack of organometallic
t
reagents is hampered by using Bu2Hg. However, the reaction
of 2 with tBu2Hg in hexane occurs only above 60 °C, affording
the novel P,P′-bis(phosphanylgermylene) LGeP(H)P(H)GeL (5)
and elemental Hg (Scheme 2). Compound 5 is obtained as
brown-red crystals in 56% yield, which are sparingly soluble
in hexane, but readily dissolve in toluene and ethereal solvents.
(11) Driess, M.; Yao, S.; Brym, M.; van Wu¨llen, C. Angew. Chem., Int.
Ed. 2006, 45, 6730.
(12) Driess, M.; Yao, S.; Brym, M.; van Wu¨llen, C. Angew. Chem., Int.
Ed. 2006, 45, 4349.

Stable DiValent Germanium Compound
Organometallics, Vol. 27, No. 14, 2008 3603
Table 1. Comparison of Selected 1H and 31P NMR Data for 1-6
13c
2
3
4
5
6
Y
Cl
5.14
PH2
4.90
1.32
-206.0
172.7
PH(SiMe3)
4.72
-0.05
-206.4
172.0
P(SiMe3)2
5.04
PH-PH-GeL
4.60
-1.48
-182.5
170.2
OTf
5.52
1H NMR (δ, ppm) γ-H
1H NMR (δ, ppm) P-H
31P NMR (δ, ppm)
1JP, H (Hz)
-192.7
Although the mechanism is still unknown, it seems reasonable
to assume that the formation of 5 proceeds via the elusive initial
product LGeP(H)HgtBu and/or LGeP(H)HgP(H)GeL and isobu-
tane. The latter reactive P-Hg intermediates readily decompose
under reductive elimination of mercury and subsequent P-P
bond formation to give 5. Similar P-P bond formation under
liberation of Hg has been observed by the reaction of primary
SifP σ-donation.15,16 In line with that, the phosphorus nucleus
in the disilylphosphane 4 resonates at lower field (-192.7 ppm)
in the 31P NMR spectrum in comparison with that of 3, and the
1
relatively small JP,Si value of 17.1 Hz (vs 30.2 Hz for 3)
indicates a lower 3s contribution of phosphorus in the P-Si
bond.15 Remarkably, the P-H proton of the PH(SiMe3) group
1
in 3 displays a doublet in the H NMR spectrum at relatively
t
and secondary phosphanes with Bu2Hg13 and decomposition
high field (-0.05 ppm), with a drastic change of ∆δ ) -1.37
ppm in comparison with 2. The 31P NMR spectrum of the P,P′-
bis(phosphanylgermylene) 5 in toluene-d8 shows a multiplet at
-182.5 ppm, representing the X,X′-part of an AA′XX′ system
of P-mercurio 1,3-diphospha-2,4-disiletanes to give 1,3-diphos-
pha-2,4-disilabicyclo[1.1.0]butanes.14
NMR Spectroscopy. In addition to EI-MS data and elemental
analyses, the composition and constitution of 2-6 are supported
by 1H, 13C, and 31P NMR spectra. The 1H and 13C NMR
resonance signals for the ꢀ-diketiminate ligand are similar to
those observed for related Ge(II) complexes.3 Notably, the ring-
methine proton (γ-H) in 6 resonates at significantly lower field
when compared with the corresponding resonances of the
phosphanyl-substituted Ge(II) complexes 2-5 and that observed
for 13 (Table 1), indicating somewhat aromatic character of the
C3N2Ge π-ring system in 6 due to partial LGe+ · · · OTf-
character.3h,12
1
(A,A′ ) H; X,X′ ) 31P; Figure 1), whereas the 31P NMR
spectrum gives a singlet at the same chemical shift. The
corresponding proton resonance is centered at unusually high
field at δ -1.48 in the 1H NMR spectrum, representing the A,A′-
part of the AA′XX′ splitting pattern and similar coupling
constants. Unlike related alkyl- or aryl-substituted P,P′-diphos-
phanes obtained and compiled by Albrand and Taieb17showing
resonances for both rac and meso diastereomers, only the meso
isomer of 5is observed in solution, which remains unchanged
even in the temperature range from -60 to 60 °C. In order to
determine the magnitudes of the coupling constants of the
AA′XX′ spin system (1JAX, 2JAX′, 3JAA′, 1JXX′), a simulation of
the spectrum was performed.18 The experimental and calculated
spectra are depicted in Figure 1a and b. While the 31P resonance
shows a significantly downfield shift compared with those in
The 1H and 31P NMR spectra of 2 confirm the presence of a
1
PH2 group. Thus, the H NMR spectrum shows a doublet at
1
1.32 ppm with a JP,H coupling constant of 172.7 Hz. In line
with that, the 31P{1H} NMR spectrum of 2 displays a singlet at
-206.0 ppm, which degenerates into a triplet in the 31P spectrum
1
1
with a similar JP,H coupling constant of 172.7 Hz. The 31P
2, 3, and 4, the JP,H coupling constants differ only a little.
Remarkably, the unusually small magnitude of the 1JP,P coupling
constant (64.7 Hz) is reminiscent of the situation in a strained
Si2P4 cage compound,19 probably due to steric reasons.
X-ray Structures. Molecular structures of 2-6 were eluci-
dated by single-crystal X-ray diffraction analysis. The ORTEP
drawings of 2-6 are shown in Figures 2–6 together with their
structural parameters. Corresponding data collection parameters
nuclei in 2-5 are strongly shielded compared with the values
observed for the monomeric diphosphanylgermylene
[{Is2FSi}(iPr3Si)P]2Ge (Is ) 2,4,6-iPr3C6H2) (-62.1 ppm),6c the
head-to-tail dimer {(iPr2P)2Ge}2 (13.8, -36.8 ppm),6b and the
intramolecularly base-stabilized diphosphanylgermylene [{(Me3-
Si)2CH}(C6H4-2-CH2NMe2)P]2Ge (-45.8 ppm),6d indicating
considerably polar character of the Ge-P σ-bond.
The monosilylated phosphane 3 displays a singlet at -206.4
ppm in the 31P{1H} NMR spectrum and a doublet with a 1JP,H
coupling constant of 172.0 Hz in the 31P spectrum. The marginal
change of the isotropic 31P chemical shift in comparison to 2 is
somewhat unexpected, since silylation of phosphorus atoms
leads usually to a higher shielding of the 31P nucleus due to
(13) (a) Baudler, M.; Zarkadas, A. Chem. Ber. 1972, 105, 3844. (b)
Yeh, J. T.; Avens, L. R.; Mills, J. L. Phosphorus Sulfur Silicon Relat. Elem.
1990, 47, 319.
(14) Driess, M.; Pritzkow, H.; Reisgys, M. Chem. Ber. 1991, 124, 1923.
(15) Driess, M.; Merz, K.; Monse´, C. Z. Anorg. Allg. Chem. 2000, 626,
2264.
(16) Driess, M.; Monse´, C.; Merz, K. Z. Anorg. Allg. Chem. 2001, 627,
1225.
(17) Albrand, J. P.; Taieb, C. In Phosphorus Chemistry Proceedings of
the 1981 International Conference; Quin, L. D., Verkade, J. G., Eds.; ACS
Symp. Ser. 171; American Chemical Society: Washington, DC, 1981.
(18) Budzelaar, P. H. M. gNMR V4.1.2.
Figure 1. (a) Experimental 31P NMR spectrum of 5 in toluene-d8
(298 K) at 161.97 MHz, δ -182.5. (b) Simulated 31P NMR
3
spectrum of 5 (X part of the AA′XX′ spin pattern: JH,H ) 18.5
1
2
1
Hz, JP,H ) 170.2 Hz, JP,H ) 10.4 Hz, JP,P ) 64.7 Hz).

3604 Organometallics, Vol. 27, No. 14, 2008
Yao et al.
structural feature similar to that of 2, whereas compound 5
(folding angle 40.6°) again adopts a strongly puckered C3N2Ge
cycle, as observed for 3. The different structural features of 3
and 5 are presumably due to the pyramidal nature of secondary
phosphanes and steric congestion around phosphorus. Going to
an almost planar configuration at phosphorus may change the
orientation of the phosphanyl group again. In fact, the phos-
phorus atom in the P(SiMe3)2 group has a very low inversion
barrier,15,16,22 leading to an almost planar trigonal coordination
mode of phosphorus with the respective sum of angles of 355.2°
in 4. Thus, the almost planar P(SiMe3)2 moiety in 4 favors a
similar orientation of the phosphanyl group toward the puckered
C3N2Ge ring to that in 2. The Ge-P distances in 3 [(2.4261(7)
Å], 4 [2.3912(8) Å], and 5 [2.408(2) Å] lie in the range of
previously reported Ge(II)-P distances of {(iPr2P)2Ge}2 and
[{(Me3Si)2CH}(C6H4-2-CH2NMe2)P]2Ge, ranging from 2.398(1)
to 2.426(1) Å.6b,d However, the latter are longer than the
corresponding value observed in 2 [2.333(1) Å] owing to steric
congestion. In line with that, the Ge-N bond lengths in 3
[2.017(2) Å], 4 [2.006(2), 2.046(2) Å], and 5 [2.028(5), 2.033(5)
Å] are also slightly longer than that in 2 [1.979(2) Å].
In spite of the sterically encumbered LGe moieties in the P,P′-
bis(phosphanylgermylene) 5, the P-P distance of 2.221(4) Å
is very close to that in P4 (2.20 Å). The latter is also similar to
the corresponding values in (mes)PH-PH(mes) (2.229 Å),23
{(2-C5H3N-6-Me)(Me3Si)2C}P(H)-P(H){C(SiMe3)2(2-C5H3N-
6-Me)} (2.222 Å),24 and (Me3Si)2C(H)PH-PHC(H)(SiMe3)2
(2.209 Å),25 respectively, which represent rare examples of PH-
terminated diphosphanes not yet structurally characterized.
The structure of the triflate complex 6 is practically identical
with that of a related diketiminate Ge(II) triflate,12 which results
from 1,4-addition reaction of Me3SiOTf to the germylene B
(Scheme 1). The rather long Ge-O(triflate) distance indicates
a pronounced tendency to a (LGe)+ · · · OTf- ion pair separation:
the Ge1-O1 distance of 2.151(3) Å is slightly longer than the
value in the similar 1,4-addition product of Me3SiOTf to B
[2.082(1) Å].12 The latter distances are much longer than typical
covalent Ge-O bonds in germoxanes (175-185 Å),26 but
shorter than the sum of the van der Waals radii of Ge(II) and
oxygen (3.67 Å).27 In line with the cationic character of LGe+,
the Ge-N bond lengths in 6 [1.931(4) and 1.932(4) Å] are
significantly shorter than the corresponding values in 1 [1.988(2)
Å]3c and only slightly longer than those observed in the
noncoordinated LGe+ cation [1.894(2) Å] in a related borate
salt.4
Figure 2. Molecular structure of 2. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for clarity.
Selected bond lengths [Å] and angles [deg]: Ge1-N1 1.979(2),
Ge1-N2 1.979(2), Ge1-P1 2.333(1), N1-C2 1.347(4), N2-C4
1.335(4), C2-C3 1.391(4), C3-C4 1.398(4), N1-Ge1-N2 91.4(1),
N1-Ge1-P1 93.45(7), N2-Ge1-P1 92.86(7), C2-N1-Ge1
122.9(2), C4-N2-Ge1 123.3(2), N1-C2-C3 122.5(3), C2-C3-C4
127.5(3), N2-C4-C3 122.9(3).
and refinement statistics are listed in Table 3, and selected
interatomic distances and angles are given in Table 2. While
compound 2 crystallizes in the monoclinic space group P21/c,
the compounds 3, 4, and 6 crystallize in the monoclinic space
group P21/n. Compound 5 crystallizes in the triclinic space group
j
P1 with a crystallographic center of inversion midway between
the two phosphorus atoms, representing the meso configuration,
similar to the configuration of 5 obtained in solution.
The compounds 2-6 consist of differently puckered six-
membered C3N2Ge rings with folding angles ranging from 22.1°
to 40.8° (Table 2). The Ge centers are three-coordinated and
adopt a pyramidal geometry. The sums of bond angles around
the Ge center range from 274.5° to 288.6°, and the degree of
pyramidalization (DP) ranges from 79% to 95% (Table 2),20
illustrating the high 4p-character of the germanium σ-orbitals
in the Ge-X (X ) O, P) bonds. In other words, the vertex of
the germanium atom is occupied by a lone pair of electrons
with pronounced 4s-character.
The structure feature of compound 2 is reminiscent of the
starting material LGeCl, 1.3c The Ge-N bond length of 1.979(2)
Å in 2 is very close to those observed in 1 [1.988(2), 1.997(3)
Å]. The Ge-P bond length of 2.333(1) Å in 2 lies between the
corresponding values seen in (C6F5)3GePH2 (2.307 Å)16 and in
the four-membered Ge2P2 ring [tBu(mes)GePH]2 (2.348 Å),
having four-coordinate germanium atoms. As expected, the
Ge(IV)-P distances are significantly shorter than those values
reported for Ge(II)-P compounds. For example, the Ge(II)-P
distances in the dimeric {(iPr2P)2Ge}2 are 2.426(1), 2.422(1),
and 2.398(1) Å,6b respectively, and the corresponding values
in the intramolecularly base-stabilized diphosphanylgermylene
[{(Me3Si)2CH}(C6H4-2-CH2NMe2)P]2Ge amount to 2.4023(4)
and 2.4114(4) Å, respectively.6d
Conclusion
The first heteroleptic ꢀ-diketiminato complex of germa-
nium(II) with a terminal PH2 group, compound 2, was success-
fully synthesized and characterized structurally. The latter
(21) Driess, M.; Pritzkow, H.; Winkler, U. Chem. Ber. 1992, 125, 1541.
(22) Examplesfortrigonal-planarsilyl-substitutedphosphoruscompounds:(a)
Westerhausen, M.; Lang, G.; Schwarz, W. Chem. Ber. 1996, 129, 1035.
(b) Franske, D.; Grissinger, A.; Hey-Hawkins, E. M.; Magull, J. Z. Anorg.
Allg. Chem. 1991, 595, 57. (c) Baker, R. T.; Whitney, J. F.; Wreford, S. S.
Organometallics 1983, 2, 1049. (d) Weber, L.; Meine, G.; Boese, R.; Augart,
N. Organometallics 1987, 6, 2484. (e) Hey, E.; Lappert, M. F.; Atwood,
J. L.; Bott, S. G. Polyhedron 1988, 7, 2083.
(23) Kurz, S.; Oesen, H.; Sieler, J.; Hey-Hawkins, E. Phosphorus Sulfur
Silicon Relat. Elem. 1996, 117, 189.
(24) Andrews, P. C.; King, S. J.; Raston, C. L.; Roberts, B. A. Chem.
Commun. 1998, 547.
The monosilylated derivative 3 has a structural feature
significantly different from that of the parent phosphanyl
compound 2. The folding angle between the planes defined by
the N1, C2, C3, C4, N2 atoms (plane 1) and the N1, Ge1, N2
atoms (plane 2) of 40.8° is much greater than that observed for
2 (26.0°). Furthermore, the P(H)SiMe3 moiety is bent away from
plane 1 in 3, in contrast to the orientation of the PH2 group in
2. Interestingly, compound 4 (folding angle 22.1°) shows a
(19) Xiong, Y.; Yao, S.; Brym, M.; Driess, M. Angew. Chem., Int. Ed.
(25) Blair, S.; Izod, K.; Taylor, R.; Clegg, W. J. Organomet. Chem.
2002, 656, 43.
(26) Baines, K. M.; Stibbs, W. G. Coord. Chem. ReV. 1995, 145, 157.
(27) Chauvin, R. J. Phys. Chem. 1992, 96, 9194.
2007, 46, 4511.
(20) Maksic´, Z. B.; Kovacˇevic´, B. J. Chem. Soc., Perkin, Trans. 2 1999,
2623.

Stable DiValent Germanium Compound
Organometallics, Vol. 27, No. 14, 2008 3605
Table 2. Selected Metrical Parameters for 2-6 (distances in Å and angles in deg)
2
3
4
5
6
Ge1-P1
2.333(1)
1.979(2)
1.979(2)
1.347(4)
1.335(4)
1.391(4)
1.398(4)
91.4(1)
2.4261(7)
2.017(2)
2.017(2)
1.325(3)
1.330(2)
1.405(3)
1.401(3)
88.58(7)
283.8
2.3912(8)
2.046(2)
2.006(2)
1.344(4)
1.313(4)
1.393(4)
1.405(4)
90.20(9)
288.6
2.408(2)
2.033(5)
2.028(5)
1.313(7)
1.301(7)
1.407(9)
1.412(9)
87.9(2)
285.0
Ge1-N1
1.931(4)
1.932(4)
1.348(5)
1.343(6)
1.385(6)
1.383(7)
93.0(2)
Ge1-N2
N1-C2
N2-C4
C3-C2
C3-C4
N1-Ge1-N2
sum of angles at Ge
sum of angles at P
degree of pyramidalization at Ge (%)a
folding angleb
277.7
274.5
280.0
85
40.8
355.2
79
22.1
277.1
83
40.6
91
26.0
95
24.4
a Reference 20. b Between the planes defined by the N1, C2, C3, C4, N2 atoms (plane 1) and the N1, Ge1, N2 atoms (plane 2).
Table 3. Crystal Data Collection and Refinement Details for the Crystal Structures
2
3
4 · 2C5H10
5
6
formula
C29H41GeN2P
521.20
0.6 × 0.5 × 0.4
monoclinic
P21/c
14.1380(5)
16.3244(6)
13.8086(5)
90.00
116.3790(10)
90.00
2855.10(18)
4
1.213
1.147
173(2)
C32H51GeN2PSi
595.40
0.6 × 0.6 × 0.6
monoclinic
P21/n
8.9098(4)
19.6084(9)
19.6505(10)
90.00
90.3640(10)
90.00
3433.0(3)
4
1.152
0.995
173(2)
C45H79GeN2PSi2
807.84
0.6 × 0.4 × 0.4
monoclinic
P21/n
11.5933(4)
22.8578(9)
18.3221(7)
90.00
93.2330(10)
90.00
4847.6(3)
4
1.107
0.744
173(2)
C58H84Ge2N4P2
1044.41
C30H41F3GeN2O3S
639.30
0.4 × 0.4 × 0.4
monoclinic
P21/n
12.087(2)
13.013(3)
24.046(5)
90.00
92.11(3)
90.00
3779.6(13)
4
1.123
0.907
173(2)
molecular weight
cryst size, mm3
cryst syst
space group
a, Å
b, Å
c, Å
0.4 × 0.3 × 0.3
triclinic
j
P1
10.8175(6)
12.0783(7)
12.6434(7)
91.550(2)
108.361(2)
111.339(2)
1441.49(14)
1
1.203
1.136
173(2)
1.72-24.99
9145
R, deg
ꢀ, deg
γ, deg
V, Å3
Z
F, Mg/m3
µ, mm-1
temperature, K
θ limit, deg
no. of measd reflns
no. of indep reflns
goodness of fit
1.61-25.00
17 566
1.47-30.63
32 207
1.43-25.00
29 934
1.69-25.00
22 709
5029 [R(int) ) 0.0895] 10 538 [R(int) ) 0.0768] 8532 [R(int) ) 0.0647] 5063 [R(int) ) 0.1193] 6653 [R(int) ) 0.0889]
1.050
1.042
1.133
0.963
0.930
no. of data, restraints, params 5029, 0, 308
10 538, 0, 351
0.0519, 0.1321
0.845, -0.676
8532, 10, 476
0.0463, 0.1259
0.640, -0.562
5063, 0, 312
0.0721, 0.1739
1.190, -1.023
6653, 76, 393
0.0591, 0.1561
0.549, -0.498
final R1, wR2a
Fmax, ∆Fmin, e Å-3
0.0449, 0.1300
∆
1.201, -0.820
a The value of R1 is based on selected data with F > 4σ(F); the value of wR2 is based on all data.
Figure 3. Molecular structure of 3. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms, except that at P1,
are omitted for the sake of clarity. Selected bond lengths [Å] and
angles [deg]: Ge1-N1 2.017(2), Ge1-N2 2.017(2), Ge1-P1
2.426(7), P1-Si1 2.2366(9), N1-C2 1.325(3), N2-C4 1.330(2),
C2-C3 1.405(3), C3-C4 1.401(3), N1-Ge1-N2 88.58(7),
N1-Ge1-P1 94.57(5), N2-Ge1-P1 100.55(5), Si1-P1-Ge1
100.98(3),C2-N1-Ge1118.7(1),C4-N2-Ge1118.5(1),N1-C2-C3
122.5(2), C4-C3-C2 126.5(2), N2-C4-C3 122.8(2).
Figure 4. Molecular structure of 4. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for clarity.
Selected bond lengths [Å] and angles [deg]: Ge1-N1 2.006(2),
Ge1-N2 2.046(2), Ge1-P1 2.3912(8), P1-Si1 2.219(1), P1-Si2
2.227(1), N1-C2 1.344(4), N2-C4 1.313(4), C2-C3 1.393(4),
C3-C4 1.405(4), N1-Ge1-N2 90.20(9), N1-Ge1-P1 103.46(7),
N2-Ge1-P1 94.93(6), Si1-P1-Si2 110.13(5), Si1-P1-Ge1
111.14(4), Si2-P1-Ge1 133.93(4), C2-N1-Ge1 124.2(2),
C4-N2-Ge1 124.0(2), N1-C2-C3 122.3(2), N1-C2-C1 119.7(2),
C2-C3-C4 127.7(3), N2-C4-C3 123.8(2).
complex is unexpectedly stable and suitable for silylation at
phosphorus to give the monosilylated derivative 3. Further
silylation of 3 leads to the cleavage of the Ge-P bond and
formation of the Ge(II) triflate 6. However, the doubly P-
silylated compound 4 is simply accessible by salt metathesis
reaction of LGeCl (1) with LiP(SiMe3)2. Reductive P-P
coupling and dehydrogenation of 2 have been achieved by the
t
reaction of Bu2Hg with 2, leading to the novel P,P′-bis(phos-
phanylgermylene) 5. The sterically encumbered novel ger-

3606 Organometallics, Vol. 27, No. 14, 2008
Yao et al.
material LGeCl, 1,3c [LiPH2(dme)],28 [LiP(SiMe3)2(dme)],29 and
tBu2Hg30 were prepared according to literature procedures.
Me3SiOTf was purchased from Aldrich and used as received. The
NMR spectra were recorded on Bruker spectrometers AS 200 and
AV 400 with residual solvent signals as internal reference (1H and
13C{1H}) or with an external reference (SiMe4 for 29Si, BF3 · Et2O
for 19F, and 85% H3PO4 for 31P, respectively). Abbreviations: s )
singlet; d ) doublet; t ) triplet; sept ) septet; mult ) multiplet;
br ) broad.
LGePH2 (2). A solution of LGeCl (1) (1.89 g, 3.60 mmol) in
diethyl ether (30 mL) was added to a suspension of [LiPH2(dme)]
(0.47 g, 3.60 mmol) in diethyl ether (40 mL) with stirring at -50
°C. The color of the solution turned immediately from yellow to
orange. After 4 h stirring, the reaction mixture was allowed to
slowly warm to room temperature and stirred overnight. Volatiles
were removed in Vacuo, and the residue was extracted with
n-hexane (100 mL). Filtration and subsequent concentration (to
about 30 mL) led, after 2 days of slow cooling to -20 °C, to the
isolation of orange crystals of 2 (1.14 g). After concentration of
the supernatant to about 10 mL and cooling to -20 °C for a further
2 days, an additional crop of 2 was isolated, affording a total yield
of 1.57 g (83%). Mp: 130-134 °C (dec). 1H NMR (200.13 MHz,
C6D6, 298 K): δ 1.13 (d, 3JHH ) 6.8 Hz, 6 H, CH MeMe), 1.19 (d,
3JHH ) 6.8 Hz, 6 H, CH MeMe), 1.30 (d, 3JHH ) 6.8 Hz, 6 H, CH
Figure 5. Molecular structure of 5. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms, except those at P1
and P1′, are omitted for clarity. Symmetry transformation used to
generate the equivalent atoms labeled with (′): 1-x, -y+1, -z.
Selected distances [Å] and angles [deg]: Ge1-N2 2.028(5),
Ge1-N1 2.033(5), Ge1-P1 2.408(2), P1-P1′ 2.221(4), N1-C2
1.313(7), N2-C4 1.301(7), C2-C3 1.407(9), C3-C4 1.412(9),
N2-Ge1-N1 87.9(2), N2-Ge1-P1 98.4(2), N1-Ge1-P1 98.7(2),
P1′-P1-Ge1 93.1(1), C2-N1-Ge1 118.8(4), C4-N2-Ge1 119.4(4),
N1-C2-C3 122.1(6), C2-C3-C4 127.1(6), N2-C4-C3
122.3(6).
1
3
MeMe), 1.32 (d, JPH ) 173 Hz, 2 H, P H2),1.47 (d, JHH ) 6.8
Hz, 6 H, CH MeMe), 1.54 (s, 6 H, NC Me), 3.47 (sept. 3JHH ) 6.8
Hz, 2 H, C HMe2), 3.66 (sept. of d, 3JHH ) 6.8 Hz, JPH ) 2 Hz, 2
H, C HMe2), 4.90 (s, 1 H, γ-C H), 7.04-7.18 (m, br, 6 H, 2,6-
iPr2C6H3). 13C{1H} NMR (50.32 MHz, C6D6, 298 K): δ 23.3, 24.7,
24.8, 26.0, 26.1, 26.2, 28.7, 28.9, 29.1 (NC Me, CH Me); 98.8 (γ-
C); 124.7, 124.8, 127.4, 140.5, 145.0, 145.2 (N C, 2,6-iPr2C6H3).
31P{1H} NMR (161.97 MHz, C6D6, 298 K): δ -206.0 (s). 31P NMR
1
(161.97 MHz, C6D6, 298 K): δ - 206.0 (t, JPH ) 172.7 Hz). IR
(KBr, cm-1): 755 (m), 764 (m), 850 (m), 934 (m), 1021 (m), 1038
(m), 1058 (w), 1099 (m), 1110 (m), 1168 (m), 1258 (s), 1314 (s),
1359 (s), 1365 (s), 1385 (s), 1435 (s), 1459 (s), 1466 (s), 1520 (s),
1556 (s), 2299 (m, P-H str.), 2866 (s), 2924 (s), 2965 (s), 3058
(m). Anal. Calcd for C29H43N2GeP: C, 66.6; H, 8.3; N, 5.3. Found:
C, 66.4; H, 8.7; N, 5.1. EI-MS: m/z (%): 490.3(25, [M - PH2]+),
475.2(8, [M - PH2 - Me]+).
LGeP(H)PSiMe3 (3). To a precooled (-60 °C) Schlenk flask
containing a solution of 2 (1.28 g, 2.45 mmol) in diethyl ether (12
mL) and triethylamine (0.70 mL, 4.90 mmol) was dropwise added
trimethylsilyl triflate (0.55 g, 2.45 mmol) with stirring. The color
of the solution turned gradually from orange to brown-red. After
2 h stirring, the reaction mixture was allowed to slowly warm to
room temperature and stirred overnight. Volatiles were removed
in Vacuo, and the residue was extracted with n-hexane (15 mL).
Concentration and storage of the brown-red extract in a -20 °C
freezer for 2 days afforded brown-red crystals of 3. Yield: 1.12 g
Figure 6. Molecular structure of 6. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for clarity.
Selected bond lengths [Å] and angles [deg]: Ge1-N1 1.931(4),
Ge1-N2 1.932(4), Ge1-O1 2.151(3), N1-C2 1.348(5), N2-C4
1.343(6), C2-C3 1.385(6), C3-C4 1.383(7), N1-Ge1-N2 93.0(2),
N1-Ge1-O1 91.8(1), N2-Ge1-O1 89.7(1), C2-N1-Ge1 122.8(3),
C4-N2-Ge1 123.3(3), N1-C2-C3 122.5(5), C4-C3-C2 127.3(4),
N2-C4-C3 122.9(4).
1
(77%). Mp: 136-140 °C. H NMR (400.13 MHz, C6D6, 298 K):
δ -0.05 (d, 1JPH ) 171 Hz, 1 H, PHSiMe3), -0.02 (d, 3JPH ) 3.2
Hz, 9 H, SiMe3), 1.12 (d, 3JHH ) 6.8 Hz, 6 H, CHMeMe), 1.19 (d,
mylene-phosphane complexes 2-5 represent a fascinating new
type of strong σ-donor phosphane ligands capable of synthesiz-
ing low-coordinate transition-metal complexes with potential
application in homogeneous catalysis. Respective investigations
are currently underway.
3
3JHH ) 6.8 Hz, 6 H, CHMeMe), 1.36 (d, JHH ) 6.8 Hz, 6 H,
3
CHMeMe), 1.51 (s, 6 H, NCMe), 1.65 (d, JHH ) 6.8 Hz, 6 H,
3
CHMeMe), 3.37 (sept. JHH ) 6.8 Hz, 2 H, CHMe2), 3.94 (sept.
3JHH ) 6.8 Hz, 2 H, CHMe2), 4.72 (s, 1 H, γ-CH), 7.03-7.17 (m,
br, 6 H, 2,6-iPr2C6H3). 13C{1H} NMR (100.61 MHz, C6D6, 298
K): δ 2.9 (d, 2JPC ) 8.8 Hz, PHSiMe3); 23.0, 24.6, 24.8, 24.8, 24.9,
25.2, 26.8, 28.9, 29.0, 29.1 (NCMe, CHMe); 96.6 (γ-C); 124.6,
124.8, 127.2, 140.2, 144.3, 145.7 (2,6-iPr2C6H3); 167.2 (NC).
31P{1H} NMR (161.97 MHz, C6D6, 298 K): δ -206.4 (s). 31P NMR
Experimental Section
1
(161.97 MHz, C6D6, 298 K): δ -206.4 (d, JPH ) 172 Hz).
General Considerations. All experiments and manipulations
were carried out under dry oxygen-free nitrogen using standard
Schlenk techniques or in an MBraun inert atmosphere drybox
containing an atmosphere of purified nitrogen. Solvents were dried
by standard methods and freshly distilled prior to use. The starting
(28) Baudler, M.; Glinka, K. Inorg. Synth. 1990, 27, 227.
(29) Fritz, G.; Hoelderich, W. Z. Anorg. Allg. Chem. 1976, 422, 104.
(30) Nugant, W. A.; Kochi, J. K. J. Organomet. Chem. 1977, 124, 271.
(31) Sheldrick, G. M. SHELX-97, Program for Crystal Structure
Determination; Universita¨t Go¨ttingen: Germany, 1997.

Stable DiValent Germanium Compound
Organometallics, Vol. 27, No. 14, 2008 3607
29Si{1H} NMR (79.49 MHz, C6D6, 298 K): δ 3.7 (d, 1JPSi ) 30.2
Hz). IR (KBr, cm-1): 444 (m), 626 (m), 748 (m), 758 (m), 794
(s), 804 (m), 834 (s), 843 (s), 928 (m), 933 (m), 1015 (m), 1059
(m), 1098 (m), 1108 (m), 1176 (m), 1228 (w), 1243 (m), 1254
(m), 1320 (s), 1355 (s), 1374 (s), 1383 (s), 1437 (s), 1462 (s), 1488
(m), 1518 (s), 1560 (s), 2244 (m, P-H str.), 2867 (s), 2889 (m),
2925 (s), 2960 (s), 3060 (w). Anal. Calcd for C32H51N2GePSi: C,
64.5; H, 8.6; N, 4.7. Found: C, 64.0; H, 8.7; N, 4.4. EI-MS: m/z
(%) 595.4 (0.9, M+), 580.3 (2.5, [M - Me]+), 490.2 (100, [M -
PHSiMe3]+).
298K): δ -182.5 (see Figure 1). IR (KBr, cm-1): 442 (w), 758
(m), 796 (m), 858 (w), 902 (w), 1020 (m), 1058 (w), 1101 (w),
1144 (w), 1172 (w), 1228 (w), 1258 (m), 1318 (s), 1376 (s), 1384
(s), 1438 (s), 1464 (m), 1529 (s), 2867 (m), 2926 (m), 2962 (s),
3059 (w). Anal. Calcd for C58H84N4Ge2P2: C, 66.7; H, 8.1; N, 5.4.
Found: C, 66.9; H, 7.9; N, 5.2. EI-MS: m/z (%) 1044.5 (0.04, M+),
490.25 (38, [1/2M - PH]+), 475.3 (24, [1/2M - PH - Me]+).
LGeOTf (6). To a precooled (-60 °C) Schlenk flask containing
a solution of LGePH2 (0.44 g, 0.84 mmol) in diethyl ether (10 mL)
and triethylamine (0.46 mL, 3.36 mmol) was dropwise added
trimethylsilyl triflate (0.37 g, 1.68 mmol) with stirring. The color
of the solution turned gradually from orange to pale yellow. After
2 h stirring, the reaction mixture was allowed to slowly warm to
room temperature and stirred overnight. Volatiles were removed
in Vacuo, and the residue was extracted with n-hexane (15 mL).
Concentration and storage of the extract in a -20 °C freezer for 2
days afforded pale yellow crystals of 6. Yield: 0.49 g (91%). Mp:
206 °C (dec). 1H NMR (200.13 MHz, C6D6, 298 K): δ 1.09 (br, 6
H, CHMeMe), 1.12 (br, 6 H, CHMeMe), 1.13 (br, 6 H, CHMeMe),
1.16 (br, 6 H, CHMeMe), 1.62 (s, 6 H, NCMe), 3.22 (br, 4 H,
CHMe2), 5.52 (s, 1 H, γ-CH), 6.94-7.16 (br, 6 H, 2,6-iPr2C6H3).
13C{1H} NMR (50.32 MHz, C6D6, 298 K): δ 22.6, 23.9, 25.4, 27.9
(NC Me, CHMe); 106.0 (γ-C); 124.7, 127.9, 128.5, 137.5, 140.3
(2,6-iPr2C6H3); 167.1 (N C). 19F{1H} NMR (188.31 MHz, C6D6,
298 K): δ -77.5 (CF3). IR (KBr, cm-1): 627 (s), 637 (w), 761
(w), 804 (m), 936 (w), 988 (s), 1003 (w), 1030 (m), 1057 (w),
1167 (m), 1182 (s), 1190 (s), 1200 (s), 1232 (s), 1253 (m), 1260
(m), 1308 (m), 1326 (s), 1357 (s), 1385 (s), 1441 (m), 1465 (m),
1543 (s), 1586 (w), 2870 (m), 2928 (m), 2964 (s), 3062 (w), 3224
(w). Anal. Calcd for C30H41N2GeF3SO3: C, 56.4; H, 6.5; N, 4.4.
Found: C, 56.2; H, 6.9; N, 4.3. EI-MS: m/z (%) 639.3 (96, M+),
490.3 (93, [M - OTf]+), 475.2 (100, [M - OTf - Me]+).
Single-Crystal X-ray Structure Determinations. Crystals were
each mounted on a glass capillary and measured in a cold N2 flow.
The data were collected on a Bruker-AXS SMART CCD diffrac-
tometer at 173(2) K (Mo KR radiation, λ ) 0.71073 Å). The
structures were solved by direct methods and were refined on F2
with the SHELX-97 software package. The positions of the H atoms
were calculated and considered isotropically according to a riding
model. All disordered groups were refined with distance restraints
and restraints for the anisotropic displacement parameters.
LGeP(SiMe3)2 (4). A solution of 1 (1.60 g, 3.04 mmol) in diethyl
ether (30 mL) was added to a solution of [LiP(SiMe3)2(dme)] (0.84
g, 3.04 mmol) in diethyl ether (30 mL) with stirring at -20 °C.
After 4 h stirring, the reaction mixture was allowed to slowly warm
to room temperature and stirred overnight. Volatiles were removed
in Vacuo, and the residue was extracted with n-hexane (60 mL).
Filtration and subsequent concentration (to about 8 mL) led, after
2 days of slow cooling to 5 °C, to the isolation of pale yellow
1
crystals of 4 (1.79 g, 89%). Mp: 125 °C (dec). H NMR (200.13
MHz, C6D6, 298 K): δ 0.43 (d, 3JPH ) 4.6 Hz, 18 H, Si Me3), 1.07
3
3
(d, JHH ) 6.8 Hz, 6 H, CHMeMe), 1.27 (d, JHH ) 6.8 Hz, 6 H,
CHMeMe), 1.29 (d, 3JHH ) 6.8 Hz, 6 H, CHMeMe), 1.52 (d, 3JHH
3
) 6.8 Hz, 6 H, CHMeMe), 1.58 (s, 6 H, NCMe), 3.39 (sept. JHH
) 6.8 Hz, 2 H, CHMe2), 3.89 (sept. of d, 3JHH ) 6.8 Hz, JPH ) 1.7
Hz, 2 H, CHMe2), 5.04 (s, 1 H, γ-CH), 7.05-7.24 (m, br, 6 H,
2,6-iPr2C6H3). 13C{1H} NMR (50.32 MHz, C6D6, 298 K): δ 5.5
(d, 2JPC ) 10.4 Hz, P[SiMe3]2); 24.1(NCMe); 24.7, 24.9, 25.2, 29.3
(CHMe); 28.2 (d, JPC ) 5.0 Hz,), 29.4 (CHMe); 101.4 (γ-C); 124.4,
125.5, 141.2, 144.3, 147.2 (2,6-iPr2C6H3); 166.3 (NC). 31P{1H}
NMR (161.97 MHz, C6D6, 298 K): δ -192.7 (s). 29Si{1H} NMR
1
(79.49 MHz, C6D6, 298 K): δ 2.0 (d, JPSi ) 17.1 Hz). IR (KBr,
cm-1): 439 (m), 483 (m), 628 (s), 680 (w), 744 (m), 757 (m), 794
(s), 833 (s), 846 (s), 937 (w), 1021 (w), 1108 (w), 1168 (m), 1239
(s), 1259 (m), 1286 (w), 1316 (s), 1360 (s), 1384 (s), 1461 (s),
1525 (s), 2869 (m), 2891 (m), 2928 (s), 2963 (s), 3061 (w). Anal.
Calcd for C35H59N2GePSi2: C, 63.0; H, 8.9; N, 4.2. Found: C, 62.9;
H, 8.4; N, 4.0. EI-MS: m/z (%) 667.6 (8, M+), 579.4 (5, [M -
SiMe3 - Me]+, 490.3 (22, [M - P(SiMe3)2]+).
LGeP(H)P(H)GeL (5). An alumimum foil-wrapped Schlenk
flask was charged with LGePH2 (0.43 g, 0.82 mmol) and Bu2Hg
t
(0.26 g, 0.82 mmol) in hexane (20 mL). This mixture was allowed
to warm to 60 °C with stirring for 48 h, and a gray precipitate of
elementary Hg was formed. After decantation, the brown-red
solution was slowly cooled to room temperature to afford brown-
red crystals of 5. Yield: 0.24 g (56%). Mp: 210 °C (dec). 1H NMR
(400.13 MHz, toluene-d8, 298 K): δ -1.48 (A part of the AA′XX′
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der Che-
mischen Industrie.
3
1
2
spin pattern: JH,H ) 18.5 Hz, JP,H ) 170.2 Hz, JP,H ) 10.4 Hz,
1JP,P ) 64.7 Hz), 1.10-1.65 (br NCCH3,CHMeMe), 3.27 (br 2H,
CHMe2), 3.65 (br 2H, CHMe2), 4.60 (s, 1 H, γ-CH), 6.65-7.66
(m, br, 6 H, 2,6-iPr2C6H3). 31P{1H} NMR (161.97 MHz, toluene-
d8, 298 K): δ -182.5 (s). 31P NMR (161.97 MHz, toluene-d8,
Supporting Information Available: CIF files giving crystal-
lographic data for 2-6. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM800269F