(N-lithioamino)diorganophosphanes and bis(N- lithioamino)organophosphanes: Synthesis and structures

Article abstract of DOI:10.1002/(SICI)1099-0682(199912)1999:12<2355::AID-EJIC2355>3.0.CO;2-H

Butyllithium (nBuLi) deprotonates Ph₂P-NHtBu in ether to give (Ph₂P- NLitBu)₂ · OEt₂. There is no Li ··· P interaction in this molecule. Three compounds of the type R'P(NLiR)₂ have been obtained by li

Full text of DOI:10.1002/(SICI)1099-0682(199912)1999:12<2355::AID-EJIC2355>3.0.CO;2-H

FULL PAPER
(N-lithioamino)diorganophosphanes and Bis(N-Lithioamino)organophosphanes:
Synthesis and Structures
Bettina Eichhorn,[a] Heinrich Nöth,*[a] and Thomas Seifert[a]
Dedicated to Professor Alfred Schmidpeter on the occasion of his 70th birthday
Keywords: Phosphane complexes / Lithium / Aminophosphanes / Hydrazides / (N-lithioamino)diorganophosphanes
Butyllithium (nBuLi) deprotonates Ph2P–NHtBu in ether to
[MeP{N(Li)iPr]2·THF}4 with an asymmetric cluster structure
give (Ph2P–NLitBu)2·OEt2. There is no Li···P interaction in comprising one LiP3, three LiPN2, three LiP2N and one LiN3
this molecule. Three compounds of the type RЈP(NLiR)2 have
been obtained by lithiation of RЈP(NHR)2, isolated as
[BuP(NLitBu)2·OEt2]2, [PhP(NLiPh)2·OEt2]2 and [PhP(NLiPh)2]2.
cluster units. The molecular structures of these compounds
as determined by X-ray structure analysis show that they are
best depicted as N-lithioaminophosphanes and not as the
Reaction of nBuLi with MeP(NHiPr)2 in hexane/THF leads to isomeric P-lithioiminophosphoranes.
Introduction
The chemistry and particularly the structural chemistry
of alkali metal hydrazides has recently been the subject of
great interest. They are versatile reagents and offer surpris-
ing structural features.[1] Amongst the series R2NϪN(R)M,
R2NϪNM2,
R(M)NϪN(M)R,
R(M)NϪNM2
and
M2NϪNM2 (M ϭ alkali metal), so far only the first three
members are known.[1] Furthermore, only very few deriva-
tives with the heavier alkali metals have been described, a
typical example being CsMeNϪN(SiMe3)2.[1d] All these
metal hydrazides are dimers, trimers or oligomers in spite
of the fact that the alkali metal cations coordinate donor
solvent molecules. The most significant feature of the hy-
drazide units is that the two nitrogen atoms are present in
a planar or almost planar coordination sphere in which the
planes around the N atoms are more or less perpendicularly
oriented to one another.
Monoaminophosphanes R2ϪnHnNϪPR2 are the mixed
higher homologues of hydrazines R2ϪnHnNϪNR2. Upon
lithiation, amidophosphanes RLiNϪPR2 form.[2] Associ-
ation of these molecules should preferentially occur by me-
ans of intermolecular Li···N interactions, although Li···P
interactions may also be present;[2] these should, however,
not be preferential due to the softer base character of the
phosphorus(III) atom. Moreover, it is well-known that ami-
nophosphanes may be involved in prototropism (A) which
can lead to imido-phosphoranes;[3] metallotropism, as de-
tonation. Another extension includes bis(phosphanyl)am-
ines (R2P)2NH and their metallation to (R2P)2NM com-
pounds (M ϭ Li, Na, K, Cs) where it has been found that
for M ϭ Li, a dimeric species with LiϪN bonds is formed,
while the sodium salt shows only NaϪP bonds.[4] Therefore
it is interesting, but difficult to predict, what kind of metal-
Ϫligand interaction can be expected for bis-metallated di-
(amino)phosphanes. For this reason we have not only inves-
tigated the metalation of monoaminophosphanes[5] but also
the bis(amino)organophosphanes. Because tris(amino)pho-
[6]
sphanes P(NHR)3 (R ϭ Me, tBu, Ch2Ph, C12H25) con-
dense too readily to give cyclophosphazanes [RHNϪPϭ
NR]2 or P4N6R6, we did not include a study of the depro-
tonation of tris(amino)phosphanes.
Results
Bis(organoamino)organophosphanes, RЈP(NHR)2
Aminophosphanes RЈ3ϪnP(NHR)n bearing primary am-
scribed in Equation (B), might therefore also be observ- ino groups are amenable to condensation. This tendency
able.[2]
increases with the number of amino groups attached to the
As far as aminophosphanes are concerned, the analogy phosphorus atom and decreases with increasing bulk of the
between hydrazines and mono-aminophosphanes can be re- P- and N-substituents. The first compound of type
adily expanded because a PIII atom allows for the formation RЈP(NHR)2 such as C5F5P(NHR)2 (R ϭ tBu, CH2Ph) was
of the series of compounds RHNϪPR2, (RHN)2PR and reported in 1966.[7] Another series of compounds
(RHN)3P and all these should be amenable to depro- PhP(NHR)2 (R ϭ Me, Et, nPr, iPr, tBu) was described in
1967.[8] They can be oxidized to PhP(X)(NHR)2 (X ϭ O,
S)
or
alkylated
to their
phosphonium salts
[a]
Institute of Inorganic Chemistry, University of Munich,
Butenandtstrasse 5Ϫ13 (Haus D), D-81377 München, Germany [PhRЈP(NHR)2]X[8] which are thermally more stable than
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ1948/99/1212Ϫ2355 $ 17.50ϩ.50/0
2355

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
the parent compounds. Furthermore, bis(arylamino)aryl- 1 and additional data (1H, 13C) are reported with the indi-
phosphanes seem to be less prone to condensation[9] and, vidual compounds in the Experimental Section.
therefore, several bis(anilido)arylphosphanes have been
characterized by spectroscopic methods.[9][10] Moreover, the
structure of mes*P[NH(mes*)]2 (mes* ϭ 2,4,6-tris-tert-bu-
tylphenyl ϭ supermesityl) has been determined by X-ray
diffraction techniques.[10] Scherer[11] and Payne[8] were able
to isolate MeP(NHtBu)2 as the most stable species amongst
bis(monoorganoamino)methylphosphanes. Even MeP-
(NHiPr)2 (1), can be isolated like MeP(NHtBu)2 (2) as the
product of aminolysis of MePCl2, as described by Equation
(1).[8] The aminolysis method has been used to prepare
compounds 1 to 5.
Table 1. Chemical shifts 31P and 15N and P-N coupling constants
for bis(organoamino)organophosphanes 1؊8 and related com-
pounds measured in C6D6
δ31P
δ15N
1J(P-N) (Hz)
MeP(NHiPr)2 (1)
MeP(NHtBu)2 (2)
PhP(NHiPr)2 (3)
PhP(NHtBu)2 (4)
PhP(NHPh)2 (5)
mesP(NHiPr)2 6
mesP(NHtBu)2 7
[mesPϪNiPr]2 8
mes*P(NHmes*)2
51.7
39.2
58.9
42.0
46.8
58.7
44.1
242.0
82
Ϫ302.1
Ϫ289.9
Ϫ304.8
Ϫ292.2
Ϫ294.6
Ϫ303.5
Ϫ298.9
Ϫ374.1
Ϫ
65.3
65.7
67.9
68.2
66.4
63.4
59.9
t 37.5
Ϫ
mes* ϭ 2,4,6-tris-tert-butylphenyl.
All compounds exhibit a single 31P NMR signal, and
the 2J(P-C) coupling constants were calculated from the sat-
ellites. Shielding of the P nucleus increases from 12.5 to
16.9 ppm by replacing iPr groups with tBu groups, and this
difference decreases in the series R ϭ Me > mes > Ph. On
the other hand, the nitrogen nuclei are better shielded by
iPr groups than by tBu groups. The shift differences are
∆δ(15N) ϭ 12.2 for the pair 1 and 2, 12.6 for the pair 3 and
4, but only 4.6 for the pair 6 and 7.
Both, 1H and 13C NMR spectra of all bis(isopropylamin-
o)phosphanes 1, 3 and 6 show nonequivalent CH3 groups
3
with different J(H-H) coupling due to the prochirality of
the iPr groups. The corresponding signal for the CH proton
is a multiplet of higher order. On the other hand, four 13C
NMR signals for the phenyl group reveal free rotation
about its PϪC bond.
There are two signals for the NH protons of bis(isoprop-
ylamino)phenylphosphane which are fairly broad. These
signals do not stem from a doublet due to coupling of the
protons with 31P because the two signals did not collapse
into a single line on 31P decoupling, nor were they affected
by proton decoupling. This is in contrast to the observation
by Payne et al.[8] who found for their compounds that the
NH signals collapsed to a singlet on irradiation at the fre-
It is interesting to note that amination of MePCl2 with
LiNHR or Me3SiNHR was unsuccessful in our hands.
Moreover, aminolysis of MePCl2 with aniline or mesidine
to MeP[NH(aryl)]2 was equally unsuccessful; this contrasts
with the aminolysis of PhPCl2 which provided the series of
bis(organoamino)phenylphosphanes 3؊5 as shown in
Equation (1). While ether is a good solvent for these reac-
tions, toluene is required for the preparation of 5 in order
to circumvent solubility problems.
In contrast, the bis(monoorganoamino)mesitylphos-
phanes 6 and 7 were readily obtained by allowing mesPCl2
(mes ϭ mesityl) to react with aminosilanes Me3SiϪNHR
as described in Equation (2). However, the formation of 7
was always accompanied by the formation of the di-phos-
phetidine 8 (Equation 3). The ratio of 7:8 before distillation
was ഠ4:1. Slow hydrolysis of 7 yielded the phosphonic acid
amide 9 as described by Equation (4), a compound that was
not obtained by direct hydrolysis of 7.
3
quency of the methine proton implying J(H-H) coupling.
On the other hand, there are also two NH signals in com-
pound 4 where there is no methine proton available for a
3J(H-H) coupling. On heating, a [D8]toluene solution of 3
led to coalescence of the two NH signals at 80°C, while all
1
other H NMR signal remain unchanged. A 13C{1H31P}
double resonance experiment clearly demonstrates that two
doublets for the CHMe2 groups are due to 3J(P-C) because
this gives rise to two singlets. Thus, the temperature-depen-
dence of the NH proton signals suggests hindered rotation
about the PϪN bond. However, there was no indication of
hindered rotation in the tert-butylaminophosphane 6, al-
though the steric requirement of the tert-butyl group would
certainly be more demanding than that of the prochiral iso-
NMR Spectra
Chemical shifts for 31P and 15N NMR, as well as coup- propyl group. However, the height of the rotational barrier
ling constants, of compounds 1؊8 are summarized in Table has not been determined experimentally
2356
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368

N-Lithioamino)diorganophosphanes and Bis(N-lithioamino)organophosphanes
FULL PAPER
1
Two H and 13C NMR signals for the isopropyl groups at the nitrogen atoms are of p-type, resulting from an al-
were also observed in the cyclophosphazane 8, appearing most planar environment of the substituents at the nitrogen
as doublets in the 1H NMR spectrum due to 3J(H-H) coup- atoms. This result already excludes any discussion that a
ling. In addition, the O-methyl groups of the mesityl sub- hindered rotation about the PϪN bond originates from π-
stituents are also not magnetically equivalent, which also bonding. Taking the molecular parameters into account, as
became apparent for the m-H atoms which appear as two obtained from the X-ray structure determination (see be-
signals and, therefore, also indicated hindered rotation. The low), single point calculations (basis set 31G*) have been
four-membered ring structure of 8 was ascertained by performed by rotating one isopropyl amino group by 360°
NMR spectroscopy, with a triplet for the 15N NMR signal leaving the rest of the molecular structure untouched. The
due to coupling to the P atoms [1J(P-N) ϭ 37.5 Hz], as result of these calculations is depicted in Figure 2.
well as by its molecular weight, and finally, by an X-ray
structure analysis.
Ab initio Calculations
Hindered rotation about the PϪN bond of bis(or-
ganoamino)organophosphanes may result in chirality at the
phosphorus center. As depicted in formulae AϪD, four dif-
ferent rotamers result as limiting cases. The conformers A
and C are chiral, while B and D are achiral due to a plane
of symmetry.
In order to obtain information on compound 3, our best-
studied bis(amino)phenylphosphane, single point calcu-
lations were performed. A simulation of the NMR spec-
trum of 3, taking its solid state structure into account, must
Figure 2. Rotational barrier calculated for PhP(NHiPr)2, using its
consider 19 spins (1H, 15N, 31P). This would be technically structural data as found for the solid state; one isopropyl group was
kept fixed, the second one was rotated about its PϪN bond
quite demanding. Therefore, we turned to NBO analysis as
implemented in the Gaussian 94 program package,[12] and
Figure 1 depicts calculated Mulliken charges and Wiberg
bond orders. The latter renders bond orders usually as too
large.
As can be seen, there are four minima on the hypersur-
face corresponding to the following rotational angles:
Ϫ100°, 130°, 40° and 0°. The corresponding conformations
are shown by structures E؊H. At a torsion angle of Ϫ50°,
the isopropyl groups overlap. In going from a cis- to a trans-
structure, an energy of 200 kcal molϪ1 is required. This bar-
rier cannot be surpassed at ambient temperature. On the
other hand, a cogwheel rotation of both isopropyl groups
Figure 1. Wiberg bond orders and Mulliken charges for PhP(NHiPr)2
will most likely lower this barrier significantly.
In spite of this, PϪN bond order values of ഠ 0.80 corre-
spond to a single bond, and calculated negative charges are
associated with the nitrogen centers as well as the ipso car-
bon atoms. Positive charges are centered at the P atom and
the hydrogen atoms. This implies localized pairs of electrons
Crystal and Molecular Structures
The molecular structures of two primary bis(amino)pho-
at the P and N centers. Surprisingly, the lone pair at the P sphanes were determined by X-ray structure analysis.
atom resides in an orbital close to sp3 while the lone pairs PhP(NHiPr)2 3, crystallizes as needles in the orthorhombic
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368
2357

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
Figure 3. a) The molecular structure of the two independent PhP(NHiPr)2 molecules in ORTEP representation; thermal ellipsoids are drawn on
˚
a 25% probability scale; selected bond lengths (A) and angles (°): P1ϪN11.687(4), P1ϪN2 1.875(4). P1ϪC1 1.844(5), N1ϪC7 1.448(7), N2ϪC10
1.476(6); Ϫ N1ϪP1ϪN2 113.7(2), N1ϪP1ϪC1 100.2(2), N2ϪP1ϪC1 99.2(2), C10ϪN2ϪP1 120.1(4), C7ϪN1ϪP1 127.9(4); P2ϪN3 1.674(5),
P2ϪN4 1.684(5), P2ϪC13 1.836(5), N3ϪC19 1.471(6), N4ϪC22 1.465(7); N3ϪP2ϪN4 113.0(2), N3ϪP2ϪC13 99.6(2), N4ϪP1ϪC22 100.0(2);
˚
˚
b) Stereoplot of the contents of the unit cell of PhP(NHiPr)2 1, along the bϪaxis; N3ϪH3 0.88 A, H3···P 1.99 A; angle N3ϪH3ϪP2 172.6°
system, space group Pca21 with Z ϭ 8. Therefore, there bonding between N and P atoms of neighboring molecules
˚
are two independent molecules in the asymmetric unit, (see with
a
N1(X)···P1(X) distance of 3.789
A
and
a
˚
Figure 3a). Both molecules differ only slightly in bond N2(X)···P2(X) distance of 3.740 A. The respective P···H dis-
lengths and possess almost the same conformation. How- tances are 2.98 and 2.87 A, and the PϪHϪN angles are
˚
ever the pyramidalization at the P atoms is significantly dif- 160.1° and 172.6°, respectively.
ferent as shown by the sum of bond angles at atom P1
In contrast to PhP(NHiPr)2 whose amino groups are pre-
(325.9°) and atom P2 (319.7°). Each of these independent sent in an anti-conformation, a syn-conformation is found
molecules are arranged in the unit cell by forming chains for PhP(NHPh)2 5 in the solid state as shown in Figure 4.
resulting from NϪH···P hydrogen bonding as shown in Fig- This compound crystallizes in the centrosymmetric mono-
ure 3b.
clinic space group Cc; the molecule itself, however only
The N atoms deviate only slightly from a planar environ- shows C1 point group symmetry.
ment because the sum of bond angles for N1 is 355.4°, for
The sum of bond angles at the P1 atom (300.7°), and
N2, 352.5°, for N3, 355.4° and for N4, 352.1°. The plane those at the N atoms (N1: 360°, N2: 358°) are indicative of
of the phenyl group does not stand perpendicular to the sp2 hybridization. An interplanar angle of the phenyl group
respective N2P plane but is twisted against it by ഠ 65°. As- bonded to atom P1 with respect to the PN2 plane is 73.5°;
sociation of the molecules results from weak hydrogen so the latter plane is not bisected. As a consequence, the
2358
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368

N-Lithioamino)diorganophosphanes and Bis(N-lithioamino)organophosphanes
FULL PAPER
N-Lithioaminophosphanes
Synthesis
It is to be expected that N-lithioaminophosphanes are
better nucleophiles than the parent aminophosphanes and
therefore might be useful reagents for the synthesis of new
ring and chain compounds based on NϪPϪN structural
units. Besides this aspect, the question as to whether these
N-metallated bis(amino)phosphanes will be present as N-
metal aminophosphanes or as P-metaliminophosphoranes
requires the determination of their structures. According to
ab initio calculations by Ashby and Trinquier[15]the
Ϫ
Ϫ
RNϪPR2 isomer is favored over the RNϭPR2 isomer.
The stabilization of the latter requires strongly eletroneg-
ative substituents such as F or CF3 bonded to the P atom.
Figure 4. ORTEP representation of a molecule of PhP(NHPh)2 5, in
the crystal; thermal ellipsoids are drawn on the 25% probability level;
˚
bond lengths (A): P1ϪN1 1.695(2), P1ϪN2 1.708(2), P1ϪC1 1.828(2),
Ϫ
Anions of type RNϭPR2 can probably only be detected
N1ϪC7 1.401(3), N2ϪC13 1.399(3), N1ϪH1 0.83, N2ϪH2 0.81;
bond angles (°): N1ϪP1ϪN2 105.4(1), N1ϪP1ϪC1 97.6(1),
N2ϪP1ϪC1 97.7(1), P1ϪN1ϪC7 127.7(1), P1ϪN2ϪC13 126.0(2),
H1ϪN1ϪP1 118, H2ϪN2ϪP1 115
if the Li counter ion is separated from the anion by com-
plexation or if replaced by a non-coordinating cation.
Otherwise one has to expect association of the N-lithioami-
nophosphanes which raises the question as to whether this
will occur through the N or/and P atoms. Indeed, com-
pounds 10؊14 are associated in the solid state as revealed
by X-ray structure determinations.
However, NMR spectroscopic data of these compounds
in solution usually showed more 31P NMR signals than ex-
pected; even when the solutions had been prepared from
well defined crystalline material. This suggests that several
solution species are formed from the dimeric and tetrameric
species. Therefore, the 1H and 13C NMR spectra were com-
plex, and it is quite evident that a detailed study of the
NMR spectra is required to characterize the solution state
of compounds 10؊14. So far, this has not yet been
achieved successfully.
interplanar angles between the C1ϪC6 phenyl plane with
respect to the other two phenyl planes are 62.3° (C7ϪC12)
and 121.2° (C13ϪC18), respectively, and it should be noted
that the phenyl groups of the aniline units are practically in
plane with the respective CNH planes (2.6°, 2.4°) allowing
for good π-overlap with the π-system of the phenyl groups.
This can also be deduced from the short CϪN bonds.
In contrast to compound 3, no NH···P or NH···N hydro-
gen bonds are present in the crystal of 5. This may be due
to the pronounced pyramidal geometry at the P center and
the near planarity of the nitrogen atoms with their phenyl
rings resulting in π-interaction. Thus PhP(NHPh)2 is a true
molecular compound in the solid state.
Metallation of mesP(NHtBu)2 with nBuLi yielded no
mesP[N(Li)tBu]2 but the P-butyl derivative 11. Therefore,
nBuLi not only deprotonated the aminophosphane but also
induced an exchange of the P-bonded organo group.
As indicated, slow hydrolysis of mesP(NHiPr)2 7 led to
the mesitylphosphonic acid amide mesP(O)H(NHiPr), 9. Its
structure was determined by X-ray methods. The molecule
crystallizes in the centrosymmetric monoclinic space group
P21/c. Figure 5a depicts the molecule. Association of the
molecules in the solid state can occur by means of NH···P,
NH···O and NH···N bonding as well as, but less likely, by
PH···O or PH···N bonding. Figure 5b, which shows four
molecules, demonstrates that an intermolecular interaction
occurs by means of NH···O hydrogen bonding with an in-
Reactions
The N-lithio derivatives of bis(amino)organophosphanes
are expected to be versatile reagents particularly for the syn-
thesis of new heterocycles. Here we describe only a single
example as a prototype, namely the synthesis of a 1,3-diaza-
2-phospha-4,5-diboretidine 15.
˚
termolecular N···O atom distance of 2.665 A and an
This new heterocycle can be considered to be a 6π-elec-
tron system provided that the P atom resides in a planar
moiety. However, the X-ray structure (vide infra) clearly dis-
proves this because the P atom is pyramidal. Nevertheless,
this example demonstrates that many other new hetero-
cyclic systems will be accessible via the new reagents, and
we will report on these later.
NϪH···O bond angle of 175.1°.
The molecular structure of the cyclophosphazane 8 (see
Figure 6) is another example of the less preferred trans-
conformation of the substituents in a centrosymmetric
structure.[13] Its bonding parameters fall into the same
range as observed for many other derivatives with a P2N2
ring. Due to steric effects, the mesityl groups are perpen-
dicular to the P2N2 ring. Moreover, the ring nitrogen atoms
are slightly pyramidal (sum of bond angles 351.5°). This is
a stronger deviation from planarity than usually observed
for trans-diazadiphosphetidines (358Ϫ360°)[14] and is prob-
ably a result of the bulky mesityl group.
Crystal and Molecular Structures
Compound 10 crystallized at Ϫ30°C from its ether solu-
tion in the monoclinic space group C2/c. It proved to be
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368
2359

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
Figure 5. a) Molecular structure of mesϪP(O)H(NHiPr) (9) in the crystal; thermal ellipsoids are represented on a 25% probability scale; selected
˚
bond lengths (A): P1ϪN1 1.618(2), P1ϪO 1.484(2), P1ϪC 1.808(2), P1ϪH 1.28(1), N Ϫ H2 0.75(1); bond angles (°): OϪP1ϪN1 118.3(1),
N1ϪP1ϪC7 102.8(1), OϪP1ϪC7 115.9(1), H1ϪP1ϪN1 104.3, H1ϪP1ϪO 108.7, C7ϪP1ϪH1 105.6; b) Association of the molecules 9 via
˚
NϪH···O interactions; the chains are oriented along the c axis; intermolecular distance O···H: 2.13(1) A, O···HϪN bond angle: 175.1°
Figure 6. Molecular structure of the diazadiphosphetidine 8; thermal
ellipsoids are depicted on a 25% probability limit; selected bond
˚
lengths (A): P1ϪN1 1.741(3), P1ϪN1A 1.727(3), P1ϪC1 1.852(4),
N1ϪC10 1.463(4); bond angles (°): N1ϪP1ϪN1a 81.5(1),
N1ϪP1ϪC1 106.51), C1ϪP1ϪN1a 108.6(1), P1ϪC1 C6 114.8(3),
C10 N1 P1a 125.7(2), C10 N1 P1 127.3(2); interplanar angle: C1 to
C6/P2N2 94.0; torsion angle: C10ϪN1ϪP1ϪN1aϪ148.8°
Figure 7. ORTEP representation of the molecular structure of 10 in
the crystal; hydrogen atoms are omitted for clarity; thermal ellipsoids
are drawn on a 25% probability level; selected interatomic distances
˚
(A): Li1ϪN1 2.018(5), Li2ϪN1A 2.075(5), Li2ϪO1 2.034(7), P1ϪN1
1.686(3), P1ϪC5 1.848(3), P1ϪC11 1.849(3), N1ϪC1 1.504(4); bond
angles (°): C5ϪP1ϪC11 99.7(1), C5ϪP1ϪN1 112.6(2), C11ϪP1ϪN1
103.0(1), P1ϪN1ϪLi1 106.9(2), P1ϪN1ϪLi2 139.4(1); other intera-
the hemietherate of [Ph2PϪN(Li)tBu]2 whose molecular
structure is depicted in Figure 7. The molecule shows a
crystallographically imposed C2 point group symmetry.
˚
tomic distances (A): Li1···C11 2.700(3), Li1···C12 2.602(6), Li2···C2
2.602(6); Li1···P1 2.983(2), Li1···Li2 2.42(1); torsion angle
C1ϪN1ϪP1ϪN1a Ϫ148.8°
2360
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368

N-Lithioamino)diorganophosphanes and Bis(N-lithioamino)organophosphanes
FULL PAPER
Because the structure of Ph2PϪNHtBu is still unknown, dination to Li atoms. There are two kinds of Li atoms.
no direct comparison of 10 to changes in bonding param- Atom Li1 is coordinated to one oxygen atom and two N
eters with the parent compound can be made. The PϪN atoms, and the sum of bond angles at the tricoordinated
bonds of 10 are shorter than in Ph2PϪNHmes atom Li1 is 359°. In addition, there is a fairly short Li1···P1
[16]
˚
˚
˚
[1.730(2)A]
but not as short as in Ph2PϪNmesLi·2OEt2 contact [2.543(5) A]. However, this is a consequence of the
[1.661(2) A]. Only the nitrogen atoms are involved in coor- geometry of the four-membered ring because the lone pair
dination with the Li atoms. The LiϪN bond to the ether- of the atom P1 presumably points outwards from the four-
˚
bearing Li atom is 0.057 A longer than the LiϪN bond to membered butterfly-shaped Li1ϪN1ϪP1ϪN2 ring. Taking
the ether-free atom Li1. However, this atom has two close the sum of bond angles at P1 (300.5°) into account, one
contacts with H atoms of two methyl groups. Moreover, can assume that hybridization at this atom is halfway be-
atom Li1 is also shielded sterically by the two phenyl groups tween p3 (270°) and sp3 (330°) so that the lone pair at the
as there are four η-LiϪC interactions. These are sufficient P atom no longer has pure s character. While the
to prevent the addition of an ether molecule to the atom N1ϪLi1ϪN2 bond angle of the four-membered ring is
Li1, and also to inhibit LiϪP coordination. The two phenyl rather sharp [81.5(2)°] the N1ϪLi2ϪN2a bond angle is qu-
groups are mutually oriented at an interplanar angle of ite open (144.9°). Atom Li2 is, however, sterically shielded
˚
110.9° to one another, and the coordination of the phenyl by two Li···H interactions ranging from 2.37 to 2.39 A.
groups C11 to C16 and C11a to C16a to the atom Li1 form While the folding angle of the four-membered ring
an interplanar angle of 45.6°. A torsion angle of 15.8° for Li1ϪN1ϪP1ϪN2 is 32.7°, the N1Li1N2 plane adopts an
the four-atom arrangement Li2ϪN1ϪC1ϪC2 reveals an al- interplanar angle of 85° with the N1Li2N2a plane. Figure
most optimal orientation for the Li2···H2C and Li2···H10A 9 shows the closest intramolecular Li···H contacts (2.4Ϫ2.7
˚
˚
“agostic” interactions with distances of 2.44 A. Thus the A) of molecule 11 which contribute to the steric shielding
structure of the anion shows an anti-conformation of the
substituents
at the PN
unit (torsion
angles
C1ϪN1ϪP1ϪC5: Ϫ121°, C1ϪN1ϪP1ϪC11: 134°).
Figure 9. View almost along the Li2N4 plane on the structural core of
molecule 11 including short HϪLi contacts
Figure 8. The molecular structure of {BuP[N(Li)tBu]2}2и2OEt2 (11) in
the crystal; hydrogen atoms omitted for clarity; thermal ellipsoids are
represented on a 25% probability scale; selected bond lengths and
˚
atom distances (A): Li1ϪN1 2.034(5), Li1ϪN2 1.983(5), Li2ϪN1
of the Li atoms. A structure similar to 11 is observed for
the solvent-free centrosymmetric molecule {PhP[N(Li)-
tBu]2}2 12, as shown in Figure 10. There are two indepen-
dent “monomers” in the asymmetric unit. The dimeric mol-
ecules exhibit eight-membered Li4N4 rings with the P atoms
bridging adjacent pairs of N atoms, or, alternatively, two
N2PLi four-membered rings are connected by two Li atoms,
1.930(5), Li2ϪN2a 1.962(5), Li1ϪO1 1.926(5), P1ϪN1 1.707(2),
P1ϪN2 1.715(2), P1ϪC1 1.876(3); P1···Li1 2.543(5), Li2···C5A
2.785(5), Li2···P1 3.046(5); bond angles (°): C1ϪP1ϪN1 100.9(1),
C1ϪP1ϪN2 100.9(1), N1ϪP1ϪN2 98.7(1), N1ϪLi1ϪN2 80.5(2),
O1ϪLi1ϪN2 142.7(3), O1ϪLi1ϪN1 135.9(2), N1ϪLi2ϪN2A
160.0(3), 85.2(2), Li1ϪN1ϪP1 85.2(2), Li2ϪN1ϪP1 113.6(2),
Li1ϪN2ϪP1 86.6(2)
The dilithio compound 11 crystallizes as a dimer of com- with the formation of a total of four LiϪN bonds.
position BuP[N(Li)tBu]2·OEt2. Its molecular structure is
Two Li centers are η6-coordinated to phenyl groups. As
shown in Figure 8. The molecule is centrosymmetric due a result of this coordination, the Li2ϪN2ϪLi1 bond angle
to a crystallographically-imposed center of inversion at the is only 93.3° (100.1° in 11), and the interplanar angle
center of an eight-membered ring. The two non-equivalent N1ϪLi1ϪN2/N2ϪLi2ϪN1a is now 99.1°. Moreover, the
PϪN bonds are slightly but significantly different and folding angle between the N2Li and the N2P plane of the
somewhat longer than in 10. They can be considered as four-membered ring is 16.5°, and, therefore the ring is
PϪN single bonds. All nitrogen atoms are involved in coor- closer to planarity than the analogous ring in 11. As ex-
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368
2361

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
Figure 10. The structure of the molecule 12 in the crystal; hydrogen
atoms are omitted for clarity and thermal ellipsoids are represented on
Figure 11. ORTEP molecular structure of {PhP[N(Li)Ph]2·2OEt2}2
(13); hydrogen atoms are omitted for clarity; thermal ellipsoid are
drawn on a 25% probability scale; selected bond lengths and atom di-
˚
a 25% probability scale; selected bond lengths and atom distances (A):
Li1ϪN1 2.017(5), Li1ϪN2 2.027(6), Li2ϪN2 1.918(5), Li2ϪN1a
1.928(6), P1ϪN1 1.686(3), P1ϪN2 1.693(2), P1ϪC7 1.867(3), Li1···P1
2.559(5), Li1···C 2.618Ϫ2.750(6); bond angles (°): N1ϪP1ϪC7
100.8(1), N2ϪP1ϪC7 99.8(1), N1ϪP1ϪN2 102.8(1), N2ϪLi2ϪN1a
149.9(2), N1ϪLi1ϪN2 81.5(2), Li1ϪN2ϪLi2 93.3(2), P1ϪN1ϪLi2A
115.8(2), P1ϪN1ϪLi1 87.0(2), P1ϪN2ϪLi1 86.5(2), P1ϪN2ϪLi2
119.6(2); interplanar angles: N2ϪLi2ϪN1A/C7ϪC12 44.3,
N2ϪLi2ϪN1a/N1ϪP1ϪN2 71.4, N2ϪLi2ϪN1A/N1ϪLi1ϪN2 99.1
˚
stances (A): Li1ϪN1 2.09(1), Li1ϪN4 2.09(2), Li1ϪN3 2.26(2),
Li1ϪO1 1.89(1), Li2ϪN2 2.03(1), Li2ϪN4 2.01(1), Li2ϪO2 1.90(1),
Li3···P1 2.55(2), Li3ϪO3 1.88(1), Li3ϪO4 1.91(1), Li4ϪN1 2.08(2),
Li4ϪN2 2.01(1), Li4ϪN3 1.95(1), P1ϪN1 1.688(6), P1ϪN2 1.683(7),
P2ϪN3 1.711(7), P2ϪN4 1.704(7), P1ϪC1 1.84(1), P1ϪC19 1.839(9),
P1···Li4 2.64(1), P1···Li3 2.55(2), L2···Li1 2.746(9), P2···Li4 3.097(8);
bond angles (°): N1ϪP1ϪN2 99.3(3), N1ϪP1ϪC1 104.7(4),
N2ϪP1ϪC1 104.3(4), N3ϪP2ϪN4 97.6(3), N3ϪP2ϪC19 100.2(4),
N4ϪP2ϪC19 101.9(4), O3ϪLi3ϪO4 114.1(8), O3ϪLi3ϪP1 126.9(9),
O4ϪLi3ϪP1 118.9(8), O1ϪLi1ϪN1 117.0(7), N1ϪLi1ϪN4 118.7(7),
O1ϪLi1ϪN4 119.6(7), N2ϪLi2ϪN4 116.1(7), O2ϪLi2ϪN2
pected for a four-membered LiN2P ring, a short Li···P dis-
118.2(7),
O2ϪLi2ϪN4
125.7(8),
N2ϪLi4ϪN3
140.7(7),
˚
N1ϪLi4ϪN2 78.0(5), N1ϪLi4ϪN3 110.7(6), P1ϪN1ϪLi4 88.3(7),
P1ϪN1ϪLi1 125.3(7), Li1ϪN1ϪLi4 71.6(8), P1ϪN2ϪLi4 90.8(8),
P1ϪN2ϪLi2 116.1(6), Li2ϪN2ϪLi4 89.0(8), P2ϪN3ϪLi4 115.2(7),
P2ϪN3ϪLi1 86.7(7), P2ϪN3ϪC25 119.3(7), P2ϪN4ϪLi1 92.3(8),
P2ϪN4ϪLi2 116.6(7), P2ϪN4ϪC31 118.3(8), Li1ϪN4ϪLi2 102.3(9)
tance of 2.559(5)A is observed.
Although compound 13 is formally related to both 11
and 12, as it is a dimeric dimetallated bis(monoorganoami-
no)organophosphane (see Figure 11), its structure turned
out to be vastly different to 12, obviously due to solvation
by diethyl ether. There is (formally) one ether molecule per
˚
Li atom. However the structure determination revealed that average only 0.01 A longer than those at P1. These bonds
there are altogether four different Li centers, one of which correspond to those found for PhP(NHPh)2.
binds two ether molecules, two others only one, while the
fourth Li center carries no ether molecule at all as seen in which turned out to be the tetramer 14, crystallizing with 5
Figure 11. molecules of THF. Four of these THF molecules are
The lithiation of MeP(NHiPr)2 led to MeP[N(Li)iPr]2
There are two molecules of 13 in the asymmetric unit bonded to Li centers, the fifth remains uncoordinated in the
¯
of the triclinic unit cell of space group P1. The differences triclinic lattice. Thus the composition of compound 14 can
between their bonding parameters are insignificant there- be described as {MeP[N(Li·THF)iPr] [N(Li)iPr]}4 THF but
fore only one molecule is depicted in Figure 11. Formally, it is surprisingly asymmetric as depicted in Figure 12.
the structure can be described as [(Et2O)2Li]-
Inspection of Figures 12 and 13 reveals that the Li atoms
[Li3(NPh)4(PPh)2 OEt2], and the anionic cage as being built are coordinated quite differently. While Figure 12 gives an
from two PN2Li four-membered rings joined by two LiN overview of the structure, Figure 13 represents more clearly
bonds to result in a structure of three condensed four-mem- its cage structure. Atoms Li2, Li4 and Li6 are tricoordin-
bered rings whose open faces are bridged by a Li(OEt2) unit ated by two N atoms and one O atom; they form a rhombus
by two nitrogen atoms. On the other hand, the (Et2O)2Li with another Li atom which coordinates to the two N
unit is joined to atom P1 with a comparatively short LiϪP atoms. Atoms Li1 and Li7 have three nitrogen atoms as
˚
distance of 2.54 A while the Li4ϪP1 distance in the four- coordination partners and these are arranged in a plane in-
˚
membered ring is 0.1 A longer. In contrast, the four-mem- cluding the Li atoms (sum of bond angles 359.9 and 360°
bered ring P2N3N4Li1 is characterized by a longer and respectively). Two of the NϪLiϪN angles subtending at Li
therefore weaker Li1ϪN3 interaction, and this causes a are comparatively small, ranging from 100.5 to 113.5°.The
˚
lengthening of the Li1ϪP2 distance to 2.746(5)A.
others are rather wide (144.8 and 149.6°). On the other
PϪN bonds to atom P1 are shorter than in the parent hand, atom Li3 has two nitrogen atoms and a phosphorus
compound PhP(NHPh)2, but are of equal lengths, while atom as coordination partners. The same number of
those at atom P2 seem to be slightly different but are on bonded atoms are observed for atom Li5 which is, however,
2362
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368

N-Lithioamino)diorganophosphanes and Bis(N-lithioamino)organophosphanes
FULL PAPER
Figure 12. a) ORTEP molecular structure of {MeP[N(Li)iPr]2·thf}4 (14); hydrogen atoms are omitted; thermal ellipsoids are represented at a
˚
25% probability level; selected bond lengths and atom distances (A): P1ϪN1 1.671(4), P1ϪN2 1.683(4), P1···Li3 2.514(8), P1···Li5 2.76(2),
P1···Li7 2.854(8), P2ϪN3 1.677(5), P2ϪN4 1.686(4), P2···Li8 2.656(9), P3ϪN5 1.687(4), P3ϪN6 1.674(4), P3···Li8 2.629(9), P4ϪN7 1.656(5),
P4ϪN8 1.682(4), P4···Li8 2.677(9), C1ϪP1 1.871(7), N1ϪLi5 1.96(2), N1ϪLi7 2.082(9), N2ϪLi1 2.17(1), N2ϪLi2 2.043(9), N3ϪLi3 2.006(9),
N3ϪLi4 2.05(1), N4ϪLi1 2.105(9), N4ϪLi2 1.97(1), N5ϪLi6 1.999(9), N5ϪLi7 2.17(1), N6ϪLi1 2.03(1), N6ϪLi5 1.96(1), N7ϪLi3 2.004(9),
N7ϪLi4 1.98(1), N8ϪLi6 2.01(1), N8ϪLi7 2.036(9); bond angles (°): N1ϪP1ϪN2 112.5(2), Li3ϪP1ϪN2 107.5(2), Li3ϪP1ϪN1 121.5(2),
C1ϪP1ϪN1 105.1(2), C1ϪP1ϪN2 108.7(2), N2ϪLi1ϪN4 10.5(4), N2ϪLi1ϪN6 113.6(4), N4ϪLi1ϪN6 144.8(5), P1ϪN1ϪLi5 68.1(2),
P1ϪN1ϪLi7 98.4(2), Li5ϪN1ϪLi7 80.3(6), P1ϪN2ϪLi2 112.2(3), P1ϪN2ϪLi1 102.9(3), Li1ϪN2ϪLi2 72.2(4),N2ϪLi2ϪN4 111.1(5),
N2ϪLi2ϪO40 123.0(4), N4ϪLi2ϪO40 116.1(4), C10ϪP2ϪN4 105.2(2) C10Ϫ P2ϪN3 106.2(3), C10ϪP2ϪLi8 118.6(3), N3ϪP2ϪN4 109.4(2)
Li8ϪP2ϪN3 107.3(3), Li8ϪP2ϪN4 109.8(2), P2ϪN3ϪLi3 103.9(4), P2ϪN3ϪLi4 96.6(4), P2ϪN4ϪLi1 105.8(3), P2ϪN4ϪLi2 104.7(4),
C20ϪP3ϪN5 109.9(2), C20ϪP3ϪN6 105.6(3), N5ϪP3ϪN6 111.3(2), P3ϪN5ϪLi6 110.8(3), P3ϪN5ϪLi7 104.4(3), P3ϪN5ϪLi5 72.6(3),
P3ϪN6ϪLi5 91.3(5), P3ϪN6ϪLi1 96.3(3), C30ϪP4ϪN7 103.0(3), C30Ϫ P4ϪN8 104.8(2), N7ϪP4ϪN8 116.7(2), C30ϪP4ϪLi8 121.6(3),
P4ϪN7ϪLi4 109.9(4), P4ϪN8ϪLi7 107.9(3), P4ϪN8ϪLi6 99.7(3), N3ϪLi3ϪN7 107.1(4), N3ϪLi3ϪP1 118.5(4), N7ϪLi3ϪP1 134.3(4),
O50ϪLi4ϪN7 128.8(5), O50ϪLi4ϪN3 125.1(5), O50ϪLi4ϪP2 107.8(4), N1ϪLi5ϪN6 148.5(7), N1ϪLi5ϪP3 120.7(5), O60ϪLi6ϪN5
124.0(6), O60ϪLi6ϪN8 128.1(5), O60ϪLi6ϪP4 117.0(4), N1ϪLi7ϪN5 109.9(4), N1ϪLi7ϪN8 149.6(6), N5ϪLi7ϪN8 160Ϫ4(5),
O70ϪLi8ϪP3 109.1(5), O70ϪLi8ϪP2 109.8(3), O70ϪLi8ϪP4 109Ϫ2(4), P2ϪLi8ϪP3 111.3(3), P2ϪLi8ϪP4 110.3(4); b) The core structure of
14 was obtained by removing all the substituents from the N and P atoms and the C atoms of the THF molecules
not part of a Li2N2 rhombus. Finally, atom Li8 binds to ecules to form, e.g. 1,3,2,4-diazadiphosphetidines[13][14] oc-
three phosphorus atoms and one oxygen atom. Li8 rep- curs by intermolecular steps. An intramolecular amine elim-
resents the only Li center which is tetracoordinated. ination to form an iminophosphane RPϭNRЈ followed by
Amongst the tricoordinated Li centers, atoms Li2 and par- dimerisation could be an alternative. This process, however,
ticularly Li5 are unusual because the sum of bond angles at might be less influenced by steric effects. An intramolecular
Li2 is 350° but for Li5 only 323° (without including a pos- process should be dependent on the conformation of the
˚
sible weak Li5ϪP3 interaction (2.605(4).A). One may see RЈP(NHR)2 molecules. It is evident that a mechanistic
this atom as being dicoordinated, particularly because the study is required to settle this question.
˚
Li2ϪN5 distance is 2.551(6) A and the N6ϪLi5ϪN1 bond
The synthesis of the bis(organoamino)organophosphanes
is readily achieved by aminolysis of the respective chloride
RЈPCl2 or by silazane cleavage. The latter method is versa-
tile and quite useful, particularly if steric effects are not
too pronounced.
As demonstrated for P(NHPh)3 (δ31P ϭ 73.8)[6f] the 31P
nucleus is better shielded in compound PhP(NHPh)2. Re-
angle is rather open [148.5(7)°]. Similar angles are also ob-
served in the structures of 11 and 12.
The five-membered ring of the 1,3,2,4,5-diazaphosphadi-
boretidine 15 is almost planar (sum of bond angles 539.8°).
It contains a pyramidal P1 atom, and planar N and B
atoms. The BϪN bond lengths are characteristic of π-
bonds. The BϪB bond length is typical for a single bond
and lies in the usual range for diborane(4) derivatives. The
placement of an iPr group by a tBu group at the N atom
also results in a better shielding of the 31P nucleus by
two mesityl groups include an interplanar angle of 64°.
14 ppm. It is also surprising that the 31P nucleus is better
shielded in PhP(NHPh)2 than in PhP(NHiPr)2. This may
be due to the larger NϪPϪN bond angle in PhP(NHiPr)2
Discussion
relative to PhP(NHPh)2, due to a higher s-character of the
The stability of primary bis(amino)organophosphanes P atom in PhP(NHPh)2. However, this may be due to the
depends on the steric shielding at the P center. This is an longer PϪN bond lengths resulting from hydrogen bonding
indication that the elimination of RNH2 from these mol- but we have not determined the degree of association in
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368
2363

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
ever, this kind of interaction is observed in
Ph2PϪN[Li(THF3)]ϪPPh2 where a cis-conformation was
determined, a result also supported by ab initio calcu-
lations.[4a] Besides these two structurally-characterized
compounds, there are three dimeric N-lithioaminophos-
phanes of type Ph2PϪN(LiиOEt2)R (formulae IϪL) where
the cis-conformation prevails. These compounds exhibit dif-
ferent degrees of P···Li interactions.[16] Thus, I and K show
weak Li···P interactions, while there is only a single one
in L. Thus an increasing steric effect due to the nitrogen
substituents decreases the probability of Li···P interactions.
These conclusions are supported by the molecular structure
of 10 where a trans-conformation is observed for the
Ph2PϪNtBu unit which inhibits a Li···P interaction. The
trans-conformation results from the NϪLi coordination,
and the η6-coordination of two phenyl groups of two differ-
ent Ph2PϪNtBu units. The consequence of this is, in ad-
dition, that only a hemietherate is formed. The PϪC bond
lengths in 11 are similar to those in 6 and L, a situation that
does not allow one to draw the conclusion as to whether the
orbitals at nitrogen mix with the PϪC* orbitals or
not.[15][16]
Figure 13. The molecular structure of 15 in the solid state; thermal
ellipsoids are represented at a 25% probability level; hydrogen atoms
˚
are omitted for clarity; selected bond lengths (A): P1ϪN1 1.743(5),
N1ϪB1 1.436(7), B1ϪB2 1.71(1), B2ϪN2 1.428(7), N2ϪP1 1.732(5),
P1ϪC1 1.841(6), B1ϪC15 1.585(8), B2ϪC24 1.605(8); bond angles
(°): C1ϪP1ϪN12 100.9(2), C1ϪP1ϪN2 101.5(2), N1ϪP1ϪN2
95.7(2), P1ϪN1ϪB1 114.8(4), P1ϪN1ϪC7 115.7(3), C7ϪN1 B1
129.4(5), N1ϪB1ϪB2 106Ϫ6(4), N1ϪB1ϪC15 125.3(5), B1ϪB2ϪN2
108.4(5), B1ϪB2ϪC24 128.1(5), B2ϪN2ϪP1 114.3(4); torsion angle:
C1ϪP1 N1ϪC7 Ϫ80.4°; interplanar angle: N1N2P1/C1 to C6 92.8°;
C15 to C20/C24 to C29 71.1°
For dimetallated bis(amino)organophosphanes, struc-
tures different to monometallated monoaminodiorgano-
phosphanes are to be expected. It is, however, somewhat
surprising that out of the four examples investigated, three
are dimeric. Of these, two have rather similar structures in
spite of the fact that 11 is an ether solvate and 12 is non-
solution. On the other hand, there is only a small variation solvated. Moreover, the formation of 11 was also not ex-
both in the shielding of the 15N nuclei as well as in the pected because the nucleophilic exchange of P-bonded or-
coupling constant 1J(P-N), irrespective of the substituent at gano groups is an exception in phosphorus chemistry. This
the P atom (Me, Ph, mes) or the N atoms (iPr, tBu, Ph). kind of reaction has been observed, for instance, in the reac-
This suggests that in solution the structural differences ob- tion of tris(2-pyridinyl)-trimethylsilylamino-phosphoranes
served for the structure of PhP(NHiPr)2 and Ph(NHPh)2 in with methyl lithium.[17] Since this exchange of R groups has
the solid state, particularly with respect to the pyramidal only been observed during the metallation of
geometry at the P atom, but also at the N atoms, becomes mesP(NHtBu)2 and not of phenyl-bis(monoorganoamino)-
less significant or even negligible. This also holds for the phosphanes it appears that the mesityl group acts as a bet-
mesityl bis(amino)phosphanes, although the coupling con- ter leaving group than a phenyl group. Thus the butyl anion
1
stants J(P-N) are noticeably smaller (by 4.5 and 8.3 Hz, not only acts as a base for NH deprotonation, but also as
respectively, for the isopropyl and tert-butyl derivative), a nucleophile, attacking the PIII center.
probably due to steric effects particularly for the sterically-
crowded mesP(NHtBu)2.
The conformation of the CP(NC)2 units in 11 and 12
can be considered as representing a trans conformation with
It would be most interesting to compare the structural dihedral CϪPϪNϪC angles of Ϫ122.2° and 102.2° for 11
parameters and their changes in the aminophosphanes with and Ϫ126.1° and 123.2° for 12. Four-membered LiN2P
those of the respective N-lithio compounds. Unfortunately rings are formed which are connected by two LiϪNϪLi
there are, at the moment, too few pairs of compounds to bonds, making all nitrogen atoms tetracoordinated. Al-
be compared in this respect. Nevertheless, the structural as- though the Li···P distances in 11 and 12 are 2.543 and 2.559
˚
pects of N-lithioaminophosphanes are attracting increasing A, respectively, and are therefore shorter than the “second-
[2,4,15,16]
interest
since the determination of the X-ray struc- ary” LiϪP bonding in I, the short distances are certainly a
ture of [Ph2PϪNPh(LiиOEt2)]2.[2] So far, Ph2PϪN(Li)mes* consequence of the geometry of the four-membered ring,
·2OEt2[16] is the only monomeric N-lithio-monoaminophos- and reflect no LiϪP single bond interaction. The rather
phane known which shows a trans-conformation with re- sharp NϪLiϪN bond angle (80.5° in 11 and 81.5° in 12) is
spect to the PϪN bond. A related compound is the lithium also an indication that LiϪP bonding is avoided. However,
salt of the bis(diphenylphosphanyl)amine Ph2PϪNHϪ the NϪPϪN bond angles are 98.7 and 102.8° in 11 and 12.
PPh2.[4] Therefore, bulky groups are necessary besides sup- In addition, the lone pair of electrons at the P atoms cannot
porting ligands such as THF or Et2O which coordinate to be of an s-type because the sum of bond angles at these
the Li centers. The trans-conformation in monoaminophos- atoms is 291° and 303.4°, respectively. There is only a
phanes inhibits any intramolecular P···Li interaction. How- change of 2.7° for the NϪPϪN bond angles in 12, com-
2364
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368

N-Lithioamino)diorganophosphanes and Bis(N-lithioamino)organophosphanes
FULL PAPER
pared to the non-metalated aminophosphane, and only a [RЈP(NLiR)2]n for n > 2. Due to the association of the lithi-
slight elongation of the PϪN bond lengths (average 0.01 ated aminophosphanes, the question as to whether these
˚
A), which has to be considered as almost negligible. How- might contain the structural unit of a P-metallated imino-
˚
ever, the PϪC bond length in 12 is 0.05 A longer than in phosphorane can be discarded, as there is no indication of
11, and this is an indication of a negative hyperconjugative short PϪN bonds (higher bond order) where Li···P coordi-
effect.[8,15,16] Most interesting is the presence of dicoordi- nation is observed. It is evident that bis-metallated bis(ami-
nated Li atoms both in 11 and 12, a situation that is similar no)phosphanes have structures completely different to bis-
to that found in tetrameric lithium tetramethylpiperidine[10] metallated hydrazines. The reason that they must have dif-
or trimeric LiN(SiMe3)2.[18] Another feature of 12 is that ferent geometries is due to their composition, which is
two of its Li centers are η6-coordinated to phenyl rings. RP(NLiR)2 for the former and R(Li)NϪN(Li)R for the lat-
This mode of coordination saturation does not occur very ter with the P atom offering at least potentially, an ad-
often, but is nevertheless not uncommon,[19] and found, for ditional coordination site
[1d]
instance, in [(Me3Si)2NϪN(Li)Ph]4
SiMe3]4
or [Ph(Li)NϪN(Li)-
[1c]
the latter also containing (η6-C6H5)2Li units.
No η6-PhLi groups are present, however, in
{PhP[N(Li)Ph]2}2и4OEt2, (13). The rather unsymmetrical
structure of this compound having four different kinds of
Li centers is unique. Once again there is a Li···P distance
Experimental Section
All experiments were performed under anhydrous conditions with
standard Schlenk techniques and nitrogen as the protecting gas.
Solvents were dried by standard procedures, distilled under a nitro-
gen atmosphere and stored under N2. The amines and the phos-
phorus halides used were commercial products, whose purity was
checked by NMR methods. Ph2PϪNHtBu was prepared as de-
scribed in the literature.[2] Ϫ M.p.Јs were determined with a Mel-
Temp apparatus. Ϫ Elemental analysis was performed at the insti-
tuteЈs microanalytical laboratory. Ϫ NMR: Jeol 270, Jeol 400 with
SiMe4 or C6D6 internal standard for 1H and 13C, internal 1 aque-
ous 15NH4ϩ solution for 15N, 85% H3PO4 internal for 31P; 1 LiCl
˚
(2.55 A) across a LiN2P ring that might indicate weak
bonding, but we regard this as a consequence of the ring
structure. One may also look upon this molecule as a con-
tact ion pair because one Li atom is not used for completing
the Li3P2N4 cage. The LiϪP atom distance of this unique
Li center, formally a (Et2O)2Liϩ unit, is 2.64 A. This dis-
˚
tance is similar to that found in lithiumphosphides,[20] e.g.
[21]
˚
[(TMEDA·Li)PPh2 (2.61 A)]
or [LiP(SiMe3)2]4·2THF
7
solution external for Li. Ϫ IR: Nicolet FT 320 (samples in Nujol/
(2.48Ϫ2.64 A).[22] While the PϪN bond lengths at the atom
P2 are not influenced by the metallation, obviously because
the P atom remains tricoordinate, the PϪN bonds at P1, the
atom which can be considered as tetracoordinated become
shorter. This is unusual insofar as an increase in coordi-
nation normally causes bond lengthening. Therefore, this
can be taken as an indication of π-bonding in the PϪN
bond, as supported by the observation that the PϪC bond
length is not affected and remains the same as in 12.
˚
Hostaflon mulls); MS: Atlas CH7. Ϫ X-ray: Siemens P4 dif-
fractometer equipped with a CCD area detector and LT2 low tem-
perature device; Mo-Kα radiation, graphite monochromator.
Bis(isopropylamino)methylphosphane
(1):
iPrNH2
(14.7 g,
249 mmol) was dissolved in diethyl ether (250 mL) and a solution
of MePCl2 (5.84 g, 50.3 mmol) in ether (50 mL) was added at 0°C
while stirring. A precipitate formed. Stirring was continued over-
night, the solid was removed by filtration, and washed three times
with 150 mL of ether. The solutions were combined, and the sol-
vent and excess amine were removed in vacuo. The residue was
then subjected to distillation. Yield: 6.3 g of 1 (78%), colorless oil
b.p. 52 °C/2 Torr. Ϫ 1H NMR (C6D6, 400 MHz): δ ϭ 0.9 (d, 3JHH ϭ
Even more unsymmetrical is the structure of 14. The
most interesting feature is the presence of a P3LiO unit be-
sides a planar N3Li unit. By maximizing the number of
LiϪN contacts, it is obvious that one LiN3 unit must finally
lead also to LiϪP contacts. The first principle leads to three
four-membered Li2N2 rhombi, a structural unit typical for
lithium amides.[19] Of the eight Li centers, seven are tricoor-
dinate, and only the Li atom of the LiP3 unit becomes tetra-
coordinated by also binding a THF molecule. Although one
can rationalize that LiϪN contacts in lithiated aminophos-
phanes are preferred as a result of the principle of hard/
soft acid-base character, LiP interactions cannot be totally
3
6.4 Hz, 6 H, CHϪCH3), 1.0 (d, JHH ϭ 6.4 Hz, 6 H, CHϪCH3),
2
1.1 (d, JPH ϭ 5.8 Hz, 3 H, PϪCH3), 1.6 (s, broad, 2 H, NH),
3.1Ϫ3.2 (m, 2 H, CHϪCH3). Ϫ 13C NMR (C6D6, 100 MHz): δ ϭ
1
3
18.7 (d, JPC ϭ 2.8 Hz, PϪCH3), 26.4 (d, JPC ϭ 6.0 Hz,
3
2
CHϪCH3), 26.9 (d, JPC ϭ 3.7 Hz, CHϪCH3), 44.7 (d, JPC
ϭ
12.6 Hz, CHϪCH3). Ϫ 15N NMR (C6D6, 27.4 MHz): δ ϭ Ϫ302.1
(d, JPN ϭ 65.3 Hz). Ϫ 31P NMR (C6D6, 81 MHz): δ ϭ 51.7 (s).
1
Ϫ C7H19N2P (162.22): calcd. C 51.83, H 11.81, N 17.27; found C
49.24, H 11.96, N 16.82.
Bis (tert-butylamino)methylphosphane (2): Prepared in a similar
avoided particularly in the lithiated bis(amino)phosphanes manner to 1 from tBuNH2 (17.3 g, 243 mmol) and MePCl2 (5.0 g,
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368 2365

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
43 mmol) in a total of 200 mL of diethyl ether. Yield: 7.6 g (84%),
21.4 Hz, o-CH3), 32.2 (d, 3JPC ϭ 10.0 Hz, CϪCH3), 51.2 (d, 2JPC ϭ
1
3
colorless oil, b.p. 53°C/5 Torr. Ϫ H NMR (C6D6, 400 MHz): δ ϭ 21.7 Hz, tert-C), 129.6 (d, JPC ϭ 4.2 Hz, m-C6H5), 137.4 (s, p-
2
2
1
1.1 (d, JPH ϭ 6.6 Hz, 3 H, PϪCH3), 1.2 (s, 18 H, CϪCH3), 1.4
C6H5), 139.3 (d, JPC ϭ 18.7 Hz, o-C6H5), 140.4 (d, JPC ϭ
(s, broad, 1 H, NH), 1.5 (s, broad, 1 H, NH). Ϫ 13C NMR (C6D6, 13.4 Hz, ipso-C6H5). Ϫ 15N NMR (C6D6, 27.4 MHz): δ ϭ Ϫ298.9
2
3
1
100 MHz): δ ϭ 23.7 (d, JPC ϭ 3.5 Hz, PϪCH3), 32.4 (d, JPC
ϭ
(d, JPN ϭ 59.9 Hz). Ϫ 31P NMR (C6D6, 81 MHz): δ ϭ 44.1 (s).
9.6 Hz, CϪCH3), 50.8 (d, JPC ϭ 13.7 Hz, tert-C). Ϫ 15N NMR
Ϫ C17H31N2P (294.42): calcd. C 69.35, H 10.61, N 9.51; found C
69.06, H 9.70, N 9.32.
2
(C6D6, 27.4 MHz): δ ϭ Ϫ289.9 (d, JPN ϭ 65.7 Hz). Ϫ 31P NMR
1
(C6D6, 80 MHz): δ ϭ 39.2 (s). Ϫ C9H23N2P (190.27): calcd. C
56.81, H 12.18, N 14.72; found C 55.72, H 12.07, N 14.01.
Di(isopropylamino)mesitylphosphane (7) and 1,3-Diisopropyl-2,4-di-
mesityl-1,3,2,4-diazadiphosphetidine (8): A solution of mesPCl2
(1.7 g, 7.6 mmol) in toluene (20 mL) was added to a stirred solution
of iPrHNϪSiMe3 (3.90 g, 29.3 mmol) in toluene (30 mL). The mix-
ture was heated at reflux for 14 h. Me3SiCl and toluene were then
stripped off from the clear orange-colored solution. The oily resi-
Bis(isopropylamino)phenylphosphane (3): Prepared analogously to 1
from iPrNH2 (20.9 g, 350 mmol) in ether (250 mL) and PhPCl2
(12.7 g, 70 mmol) in ether (50 mL). Isolated by distillation, b.p.
76Ϫ78°C /0.2 Torr as an oily liquid. On standing at 4°C, crystals
formed with m.p. 6°C. Yield: 12.6 g of 3 (79%). Ϫ 1H NMR (C6D6,
1
due yielded 1.7 g of 7 (35 mmol), b.p. 109°C/0.1 Torr. Ϫ H NMR
3
3
3
(C6D6, 400 MHz): δ ϭ 1.0 (d, JHH ϭ 6.3 Hz, 6 H, CHϪCH3 ),
400 MHz): δ ϭ 1.0 (d, JHH ϭ 6.2, CH-CH3), 1.1 (d, JHH
ϭ
3
1.3 (d, JHH ϭ 6.3 Hz, 6 H, CHϪCH3 ), 2.1 (s, broad, 1 H, NH),
6.3 Hz, 6 H, CHϪCH3), 1.7 (s, broad, 1 H, NH), 1.75 (s, broad, 1
H, NH), 3.2 (m, 2 H, CHϪCH3, 7.1Ϫ7.7 (m, 5 H, C6H5). Ϫ 13C
2.2 (s, broad, 1 H, NH), 2.3 (s, 3 H), 2.6 (s, 6 H), 3.3 (m, 2 H,
CHCH3), 6.7 (2, 2 H, C6H2). Ϫ 13C NMR (C6D6, 67.9 MHz): δ ϭ
3
NMR (C6D6, 67.9 MHz): δ ϭ 26.5 (d, JPC ϭ 6.1 Hz, CHϪCH3),
3
3
2
20.8 (s, p-CH3), 22.7 (d, JPC ϭ 19.8 Hz, o-CH3), 26.3 (d, JPC
ϭ
26.8 (d, JPC ϭ 4.1 Hz, CHϪCH3), 46.2 (d, JPC ϭ 7.5 Hz,
3
3
4.6 Hz, CHϪCH3), 26.5 (d, JPC ϭ 7.7 Hz, CHϪCH3), 47.8 (d,
CHϪCH3), 127.7 (s, p-C6H5), 128.1 (d, JPC ϭ 4.1 Hz, m-C6H5),
2JPC ϭ 32.1 Hz, CHϪCH3), 129.5 (d, 3JPC ϭ 3.8 Hz, m-C6H5), 17.8
2
1 J
131.1 (d, JPC ϭ 15.3 Hz, o-C6H5), 148.0 (d,
ϭ 5.1 Hz, ipso-
PC
1
C6H5). Ϫ 15N NMR (C6D6, 27.4 MHz): δ ϭ Ϫ304.8 (d, JPN
ϭ
1
(s, p-C6H5), 139.2 (s, o-C6H5), 139.4 (d, JPC ϭ 17.6.1 Hz, ipso-
C6H5). Ϫ 15N NMR (C6D6, 27.4 MHz): δ ϭ Ϫ303.5 (d, JPN
ϭ
1
67.9 Hz). Ϫ 31P NMR (C6D6, 81 MHz): δ ϭ 58.9 (s). Ϫ C12H21N2P
(224.29), calcd. C 64.26, H 9.44, N 12.49; found C 63.72, H 8.94,
N 12.47.
63.4 Hz). Ϫ 31P NMR (C6D6, 81 MHz): δ ϭ 58.7 (s). Ϫ C15H27N2P
(266.37): calcd. C 67.64, H 10.22, N 10.52; found C 64.75, H 9.90,
N 10.11.
Bis(tert-butylamino)phenylphosphane (4):[7] Prepared analogously
to 1 from tBuNH2 (15.0 g, 210 mmol) and PhPCl2 (5.7 g, 32 mmol)
in 200 mL of ether. Yield: 5.9 g of 4 (73%), slightly yellow oil, b.p.
From a similar reaction, using (4.0 g of iPrHNϪSiMe3, 30 mmol),
1.7 g of MesPCl2, 7.6 mmol) in toluene (20 mL), 1.7 g of 7 was
obtained by distillation. A non-volatile oil remained which was dis-
solved in CHCl3 (5 mL). On cooling large red needles of 8 sepa-
rated, m.p. 155°C. Yield: 0.5 g of 8 (30%). Ϫ 1H NMR (CDCl3,
1
4
98°C/0.8 Torr. Ϫ H NMR (C6D6, 400 MHz): δ ϭ 0.0 (d, JPH
ϭ
0.5 Hz, 18 H, CϪCH3), 1.5 (s, broad, 1 H, NH), 1.7 (s, broad, 1
H, NH), 6.9Ϫ7.3 (m, 5 H, C6H5). Ϫ 13C NMR (C6D6, 100 MHz):
δ ϭ 32.7 (d, 3JPC ϭ 8.2 Hz, CϪCH3), 51.1 (d, 2JPC ϭ 16.1 Hz, tert-
3
400 MHz): δ ϭ 0.8 (d, JHH ϭ 6.4 Hz, 6 H, CHϪCH3), 0.81 (d,
3JHH ϭ 6.4 Hz, 6 H, CHϪCH3), 2.3 (s, mesitylϪCH3), 2.7 (s, mes-
itylϪCH3), 3.1 (s, mesitylϪCH3), 2.9 (m, 2 H, CHϪCH3). Ϫ 13C
3
C), 127.2 (s, p-C6H5), 127.7 (d, JPC ϭ 4.2 Hz, m-C6H5), 130.1 (d,
1
2JPC ϭ 17.2 Hz, o-C6H5, 148.0 (d, JPC ϭ 3.5 Hz, ipso-C6H5). Ϫ
3
NMR (CDCl3, 100 MHz): δ ϭ 3.4 (d, JPC ϭ 7.4 Hz, SiCH3), 25.6
1
15N NMR (C6D6, 27.4 MHz): δ ϭ 292.3 (d, JPN ϭ 68.2 Hz). Ϫ
3
3
(d, JPC ϭ 7.5 Hz, CHϪCH3), 25.8 (d, JPC ϭ 7.6 Hz, CHϪCH3),
31P NMR (C6D6, 81 MHz): δ ϭ 42.0 (s). Ϫ C14H25N2P (252.34),
2
3
48.6 (d, JPC ϭ 10.9 Hz, CH), 127.1 (d, JPC ϭ 2.5 Hz, m-C6H5),
calcd. C 66.64, H 9.99, N 11.27; found C 66.36, H 9.75, N 11.10.
2
128.1 (s, p-C6H5), 130.7 (d, JPC ϭ 18.6 Hz, o-C6H5), 147.2 (d,
1JPC ϭ 20.6 Hz, ipso-C6H5). Ϫ 15N NMR (CDCl3, 27.4 MHz): δ ϭ
Bis(anilido)phenylphosphane (5): PhPCl2 (4.5 g, 25 mmol) was dis-
solved in toluene (50 mL), and a solution of aniline (9.3 g,
100 mmol) in toluene (100 mL) was added with stirring in such a
manner that the temperature of the resulting suspension never ex-
ceeded 25°C. After stirring overnight, the insoluble material was
removed by filtration and washed with a total of 100 mL of diethyl
ether. (The solution may turn turbid.) The solid was then removed
after several hours. The combined solutions were reduced to 30 mL
in volume. The remaining solution was layered with pentane. After
cooling to 0°C a crystalline solid separated, m.p. 70Ϫ72°C. Yield:
3.0 g of 5 (42%). Ϫ 1H NMR (C6D6, 400 MHz): δ ϭ 4.4 (s, broad,
2 H, NH), 6.6Ϫ7.7 (m, 15 H, C6H5). Ϫ 13C NMR (C6D6,
100 MHz): δ ϭ 117.0. (d, 3JPC ϭ 11.7 Hz, m-C6H5), 120.3, s, 128.7
Ϫ374.1 (t, JPN ϭ 37.5 Hz). Ϫ 31P NMR (CDCl3, 81 MHz): δ ϭ
1
242.0 (s). Ϫ MS (70 eV); m/z (%): 414 (75) [Mϩ], 371 (5) [ Mϩ
Ϫ
iPr], 295 (100) [ M•ϩ Ϫ mes], 207 (25) [ Mϩ Ϫ mesNPiPr], 149
(35). Ϫ C12H30N4P2 (290.): calcd. C 69.54, H 8.75, N 6.76; found
C 68.48, H 8.33, N 6.68.
Mesitylphosphinic Acid tert-Butylamide (9): From a solution of 7 in
C6D6 which was kept in a NMR tube fitted with a plastic cap, a
few crystals separated within 5 weeks which were characterized as
9 by X-ray structure analysis only. Attempts to hydrolyze 7 with an
ether solution saturated with water gave no 9 on attempts to crys-
tallize the product from benzene.
N-Lithio(organoamino)phosphanes
3
2
(d, JPC ϭ 4.0 Hz, m-C6H5), 129.0, s, 129.5, s, 130.2 (d, JPC
ϭ
1
These compounds were prepared from the (organoamino)organo-
phosphanes Ph2PϪNHtBu, MeP(NHR)2, PhP(NHR)2 and
MesP(NHR)2 by treating ether or toluene solutions with an equiva-
lent amount of nBuLi in hexane at Ϫ78°C. The solutions were then
kept at reflux for 1 h, reduced in volume and kept at low tempera-
ture for crystallization.
17.0 Hz, o-C6H5), 141.7, s, 145.7 (d, JPC ϭ 13.8 Hz, ipso-C6H5).
1
Ϫ
15N NMR (C6D6, 27.4 MHz): δ ϭ Ϫ294.6 (d, JPN ϭ 66.4 Hz).
Ϫ
31P NMR (C6D6, 81 MHz): δ ϭ 46.8 (s). Ϫ C18H17N2P (297.32):
calcd. C 73.96, H 5.86, N 9.58; found C 72.15, H 5.87, N 9.36.
Bis(tert-butylamino)mesitylphosphane (6): Prepared analogously to
7 from mesPCl2 (1.2 g, 5.5 mmol) and tBuHNϪSiMe3 (3.2 g,
22 mmol) in 30 mL of toluene. Yield: 1.17 g of 6 (4.0 mmol, 72%),
b.p. 100°C/0.1 Torr, yellow oil. Ϫ 1H NMR (C6D6, 400 MHz): δ ϭ
1.2 (s, 18 H, C- CH3 ), 2.3 (s, 3 H, p-CH3), 2.2 (s, broad, 1 H, NH),
2.3 (s, broad, 1 H, NH), 2.6 (s, 6 H, o-CH3), 6.8 (s, 2 H, m-C6H2).
Since the crystals deteriorated quite rapidly when the solvent was
removed, no elemental analysis was performed. Their composition
follows from the crystal structure analysis.
Hemietherate of N-Lithio-N-tert-butylamino-diphenylphosphane
Ϫ
13C NMR (C6D6, 100 MHz): δ ϭ 20.9 (s, p-CH3), 22.5 (d, 3JPC ϭ (10): Ph2PϪNHtBu (540 mg, 2.1 mmol) dissolved in ether (10 mL)
2366
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368

N-Lithioamino)diorganophosphanes and Bis(N-lithioamino)organophosphanes
FULL PAPER
Table 2. Crystal data and data collection parameters
Compound
Chem. formula C12H21N2P
Form. wt. 224.28
3
5
8
9
10
11
12
13
14
15
C18H17N2P
292.31
C12H18NP
207.24
C12H20NOP
225.26
C36H50Li2-
C16H37Li2- C14H23Li2N2P
C52H70Li4N4O4P2
904.32
C48H108Li8- C32H45B2N2P
N2OP2
602.60
N2OP
318.33
N8O5P4
1056.82
264.19
510.29
Cryst. size [mm] 0.2 ϫ 0.28 ϫ 0.470.2 ϫ 0.2 ϫ 0.25 0.15 ϫ 0.2 ϫ 0.3 0.2 ϫ 0.2 ϫ 0.3 0.2 ϫ 0.2 ϫ 0.2 0.3 ϫ 0.3 ϫ 0.3 0.28 ϫ 0.33 ϫ 0.47 0.2 ϫ 0.25 ϫ 0.25 0.2 ϫ 0.2 ϫ 0.3 0.1 ϫ 0.2 ϫ 0.2
Cryst. system
Space group
Orthorhombic Monoclinic
Triclinic
P-1
Monoclinic
P2(1)/c
8.085(4)
18.767(6)
9.541(5)
90
112.17(2)
90
1341(1)
4
Monoclinic
C2/c
12.316(7)
16.406(9)
17.158(9)
90
96.34(2)
90
3446(3)
4
Monoclinic
P2(1)/n
10.093(3)
10.079(3)
21.084(7)
90
94.561(12)
90
2138(1)
4
Triclinic
P1bar
Triclinic
P1bar
Triclinic
P1bar
Monoclinic
P2(1)/c
19.81(2)
9.442(6)
15.97(2
90
95.48(5)
90
2974(7)
4
Pca2(1)
9.142(2)
15.954(2)
18.981(2)
90
Cc
˚
a, [A]
13.102(5)
11.549(4)
10.655(3)
90
7.599(9)
8.380(7)
10.189(13)
79.31(5)
81.16(3)
70.15(3)
597(1)
10.110(7)
11.720(9)
14.727(9)
80.04(2)
74.53(2)
73.75(1)
1605(2)
4
13.4843(3)
16.0554(4)
25.3989(4)
83.475(1)
79.746(1)
82.964(1)
5346.4(2)
4
12.786(5)
14.124(7)
20.037(9)
77.97(2)
78.37(2)
66.88(2)
3226(3)
2
˚
b, [A]
˚
c, [A]
α, [°]
β, [°]
γ, [°]
90
90
106.50(1)
90
3
˚
V, [A ]
2768.4(8)
8
1546(1)
4
Z
2
ρ(calc), [Mg/m3] 1.076
1.256
1.153
0.194
1.116
0.183
1.162
0.156
0.989
0.130
1.093
0.157
1.123
0.126
1.088
0.161
1.140
0.115
µ [mmϪ1
]
0.173
0.173
F(000)
976
616
224
488
1296
704
568
1934
1152
1104
Index range
Ϫ1 Յ h Յ 10
0 Յ k Յ 18
Ϫ 21 Յ l Յ21
48.00
293(2)
4535
Ϫ17 Յ h Յ 16
Ϫ14 Յ k Յ 14
Ϫ12 Յ l Յ 12
57.28
193(2)
4282
Ϫ9 Յ h Յ 9
Ϫ8 Յ k Յ 8
Ϫ9 Յ h Յ 9
Ϫ15 Յ h Յ 15 Ϫ10 Յ h Յ 10 Ϫ12 Յ h Յ 12
Ϫ14 Յ h Յ 14
Ϫ16 Յ k Յ 16
Ϫ26 Յ l Յ 24
43.94
173(2)
19811
Ϫ13 Յ h Յ 12 Ϫ15 Յ h Յ 16
Ϫ18 Յ k Յ 17 Ϫ10 Յ k Յ 10
Ϫ25 Յ l Յ 25 Ϫ17 Յ l Յ 17
Ϫ14 Յ k Յ 24 Ϫ21 Յ k Յ 21 Ϫ10 Յ k Յ 11 Ϫ15 Յ k Յ 14
Ϫ13 Յ l Յ 12 Ϫ12 Յ l Յ 11 Ϫ22 Յ l Յ 22 Ϫ23 Յ l Յ 23 Ϫ18 Յ l Յ 18
54.44
213
3154
1676
1499
2 θ [°]
57.30
193
7483
2355
1416
59.00
183(2)
9970
3469
2761
46.52
183
8744
2907
2589
57.62
213
8926
4850
2738
54.78
193
46.52
213
Temp, [K]
Refl. collected
Refl. unique
Refl. observed
(4σ)
15578
8884
4845
11800
3259
2296
4234
3256
2973
2831
10544
6480
R (int.)
0.0598
291
0.0396/2.9819
0.0201
258
0.0136/0.8099
0.0451
127
0.1124
150
0.0461
296
0.0303
208
0.0501
343
0.0539/1.1681
0.0755
1040
0.0419/29.9749
0.0812
679
0.0922
347
No. variables
Weighting
scheme[a] x/y
GOOF
0.0846/0.6542 0.0386/0.711
0.0001/5.9234 0.0410/2.018
0.2310/1.4891 0.1701/2.0266
1.078
1.121
1.059
1.097
1.314
1.152
1.107
1.096
1.082
1.097
Final R (4σ)
Final wR2
0.0550
0.1266
0.0298
0.0668
0.118
0.0516
0.1534
0.484
0.0436
0.0930
0.213
0.0696
0.1087
0.337
0.0583
0.1297
0.594
0.0445
0.1131
0.228
0.1134
0.2185
0.522
0.1038
0.2684
1.082
0.0892
0.2319
0.360
Larg. res. peak 0.181
3
˚
[e/A ]
2
[a] wϪ1 ϭ σ2Fo2 ϩ (xP)2 ϩ yP; P ϭ (Fo2 ϩ 2Fc )/3.
was treated at Ϫ70°C with 1.4 mL of a BuLi solution in hexane Tetrameric
Bis(N-lithio-isopropylamino)methylphosphane-tetra-
(2.2 mmol). After refluxing and volume reduction to ca. 1/3, crys-
tals were grown at Ϫ30°C, and selected at this temperature for
X-ray crystal structure analysis. NMR (supernatant solution): 31P
NMR (ether, 81 MHz): several signals in the range δ ϭ 43.6Ϫ55.9,
hydrofuran (14): MeP(NHiPr)2 (830 mg, 5.1 mmol) in THF (20 mL)
was treated with nBuLi (6.71 mL, 10.8 mmol). A clear yellow solu-
tion formed on heating at reflux. Crystals separated at Ϫ30°C.
Yield: 910 mg of 14 (72%). NMR (supernatant solution and crys-
tals): 31P NMR (C6D6, 81 MHz): several signals in the range δ ϭ
24.0 to 39, main signal at 26.5 (m, J ϭ 68.5 Hz). Ϫ 7Li NMR
(77.8 MHz): δ ϭ 1.7 (s, broad).
7
Ϫ Li NMR (77.8 MHz): δ ϭ 1.4 (s, broad).
Dimeric
Bis(N-lithio-tert-butylamino)butylphosphane
(11):
mesP(NHtBu)2 (0.34 g, 1.7 mmol) dissolved in 10 mL of ether was
metallated with 2.24 mL of a 1.56  solution of nBuLi in hexane.
The yellow solution was reduced under vacuum, and was kept for
3 weeks at Ϫ30°C for crystallization. Clear yellow crystals of 11
had then separated. NMR (supernatant solution): 31P NMR (ether/
hexane, 81 MHz): δ ϭ 96.9 (s), 93.6 (s), 89.6 (s) Ϫ 7Li NMR
(77.8 MHz): δ ϭ 2.5 (s, broad), 2.2 (s, broad).
X-ray Structure Determinations
Crystals from the solutions were transferred at about Ϫ30°C in
precooled perfluorether oil, and single crystals were selected. The
selected crystal was quickly mounted on the tip of a glass fiber and
then rapidly transferred to the goniometer head flushed with a gas
stream of N2 cooled to Ϫ90°C. The crystal quality was checked by
reflection profiles. The unit cell dimensions were calculated from
the data on 4 different sets of data of 15 frames each recorded at
different φ and χ angles, by rotating φ by 0.3°. Having obtained
satisfactory results, data collection was started (10s exposure per
frame, 1480 frames collected in the hemisphere mode). Data were
reduced by the program SAINT.[23] No absorption correction was
applied. The structures were solved by direct methods (SHELXL
programs[24]) and non-hydrogen atoms were given anisotropic ther-
Dimeric
Bis(N-lithio-tert-butylamino)phenylphosphane
(12):
PhP(NHtBu)2 (990 mg, 3.9 mmol) dissolved in toluene (30 mL) was
metallated with nBuLi in hexane (5.2 mL, 8.27 mmol). The yellow
solution was reduced to ഠ 10 mL. Yellow crystals grew at Ϫ30°C.
Yield: 900 mg of 12 (86%). NMR (supernatant solution): 31P NMR
(C6D6, 81 MHz): δ ϭ 94 (s). Ϫ 7Li NMR (77.8 MHz): δ ϭ Ϫ2.3 s,
1.4 (s, broad), 2.2 (s, broad).
Dimeric Bis(N-lithioanilino)phenylphosphane bis(ether) (13):
PhP(NHPh)2 (690 mg, 2.4 mmol) dissolved in ether (20 mL) was mal parameters. Although most H positions could be detected,
metallated at Ϫ78°C with nBuLi (3.2 mL, 4.96 mmol) in a hexane/ these were calculated and refined with a riding model and isotropic
ether mixture (3.2 mL hexane, 5 mL ether). A solid formed which Ui adopted to Ueq of the respective carbon atom. It should be
dissolved on heating. Yellow crystals of 13 separated from the yel-
noted that the refinement of the structure of compounds N-li-
thioamidophosphanes 12, 13, and 14 converged at comparatively
low solution at Ϫ30°C. NMR (supernatant solution): 31P NMR
(ether, 81 MHz): several signals in the range of δ ϭ 16Ϫ88.2 (m). high R values. This is due to the fact that the crystal quality was
Ϫ
7Li NMR (77.8 MHz): δ ϭ Ϫ0.2 (s, broad), 1.1 (s, broad), 1.7
not an optimum, leading also to rather high Rint values; moreover
(s, broad), 2.8 (s, broad).
the diffracting power was not excellent, e. g. there were only few
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368
2367

B. Eichhorn, H. Nöth, T. Seifert
FULL PAPER
[5]
The lithiation of [tBuHNϪPNtBu]2 has recently been reported:
I. Schranz, L. Stahl, R. J. Staples, Inorg. Chem. 1998, 37,
1493Ϫ1498.
reflection at 2Θ > 40° with I > 3σ(I). Several crystals of these com-
pounds had been measured without improving the result. Table 4
contains relevant information on the crystallographic data and
structure refinement. Additional material (without structure factor
tables) are deposited with the Cambridge Crystallographic Data
Centre as supplementary publication numbers CCDC 102 977 to
102 986. Copies of the data can be obtained on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, U. K. by quoting
the authors, the journal citation [Fax: (internat.)ϩ44-1223/336-033;
E-mail: deposit@ccdc.cam.uk].
[6] [6a]
R. R. Holmes, J. A. Foster, J. Am. Chem. Soc. 1960, 82,
[6b]
5509. Ϫ
R. R. Holmes, J. Am. Chem. Soc. 1961, 83, 1334.
[6c]
Ϫ
R. R. Holmes, J. A. Forstner, Inorg. Chem. 1963, 2,
[6d]
[6e]
380Ϫ384. Ϫ
A. Michaelis, Ann. Chem. 1903, 336,129. Ϫ
R. B. Flint, P. I. Salzberg, U. S. Patent 2151 389 Chem. Abstr.
[6f]
1939, 33, 5097. Ϫ
A. Tarassoli, R. C. Haltiwanger, A. D.
Norman, Inorg. Nucl. Chem. Lett. 1980, 16, 27Ϫ29.
M. G. Barlow, R. N. Haszeldine, H. G. Higson, J. Chem. Soc.
C 1966, 1592Ϫ1598.
[7]
[8]
A. P. Lane, D. A. Morton-Blake, D. Payne, J. Chem. Soc. A
1967, 1492Ϫ1498.
[9]
Y. G. Trishin, V. N. Chistokletov, A. A. Petrov, Zh. Obsh. Khim.
1979, 49, 39Ϫ44.
Acknowledgments
[10]
M. F. Lappert, M. J. Hade, A. Singh, J. L. Atwood, R. D.
Rogus, R. Shakir, J. Am. Chem. Soc. 1983, 105, 302Ϫ304.
O. J. Scherer, G. Schnabl, Chem. Ber. 1976, 109, 2996Ϫ3004.
Gaussian 94, Revision D.4; M. J. Frisch, J. A. Pople et al.,
Gaussian Inc. Pittsburgh PA, 1995.
We thank Chemetall GmbH for generous support, Mrs D. Ewald
for recording the mass spectra, Dipl.-Chem. M. Vosteen and Mr.
P. Mayer for recording numerous NMR spectra and Dipl.-Chem.
W. Lippert for help with the MO calculations.
[11]
[12]
[13]
[14]
S. Pohl, Z. Naturforsch. Teil B, 1979, 34, 256Ϫ261.
R. Keat, in The Chemistry of Inorganic Homo- and Heterocycles
(Eds.: I. Haiduc, D. B. Sowerby), Academic Press, New York,
London, Sidney, 1971, p. 4379 ff.
G. Trinquier, M. T. Ashby, Inorg. Chem. 1994, 33, 1306Ϫ 1313.
N. Poetschke, M. Kiefer, M. A. Khan, E. Niecke, M. T. Ashby,
Inorg. Chem. 1997, 36, 4087Ϫ4093.
A. Steiner, D. Stalke, Angew. Chem. 1995, 107, 1908Ϫ1910; An-
gew. Chem. Int. Ed. Engl. 1995, 34, 1752Ϫ1754.
D. Mootz, A. Zinnius, B. Böttcher, Angew. Chem. 1969, 81,
398Ϫ399; Angew. Chem. Int. Ed. Engl. 1969, 8, 378Ϫ379.
F. Pauer, P. P. Power, Chapter 8 in Lithium Chemistry (Eds.: A.-
M. Sapse, P. von Rague-Schleyer), J. Wiley and Sons, Intersci-
ence Publ. New York, Chichester, Brisbane, Toronto, Singa-
pore, 1995.
[1] [1a]
N. Metzler, H. Nöth, H. Sachdev, Angew. Chem. 1994, 106,
[15]
[16]
1838Ϫ1840; Angew. Chem. Int. Ed. Engl. 1994, 33, 1746Ϫ1748.
[1b]
Ϫ
H. Nöth, H. Sachdev, M. Schmidt, H. Schwenk, Chem.
Ber. 1995, 128, 105Ϫ113. Ϫ [1c] B. Gemünd, H. Nöth, H. Sach-
[1d]
[17]
[18]
[19]
dev, M. Schmidt, Chem. Ber. 1996, 129, 1493Ϫ1496. Ϫ
J.
Knizek, I. Krossing, H. Nöth, H. Schwenk, Th. Seifert, Chem.
[1e]
Ber./Recueil 1997, 130, 1053Ϫ1062. Ϫ
U. Klingebiel, S. Di-
elkus, C. Drost, R. Herbst-Irmer, Angew. Chem. 1993, 105, 1689
[1f]
Ϫ1690; Angew. Chem. Int. Ed. Engl. 1993, 32, 1625. Ϫ
C.
Drost, C. Jäger, S. Freitag, U. Klingebiel, M. Noltemeyer, G.
M. Sheldrick, Chem. Ber. 1994, 127, 8435Ϫ847. Ϫ K. Bode,
U. Klingebiel, M. Noltemeyer, H. WitteϪAbel, Z. Anorg. Allg.
Chem. 1995, 621, 500Ϫ505.
[20]
[21]
see ref.[19] Chapter 9.
[2]
[3]
M. T. Ashby, Z. Li, Inorg. Chem. 1992, 31, 1321Ϫ1322.
H. Rossknecht, A. Schmidpeter, Z. Naturforsch. Teil B, 1971,
26, 81Ϫ82.
R. E. Mulvey, K. Wade, D. R. Armstrong, G. T. Wells, R.
Snaith, W. Clegg, D. Reed, Polyhedron 1987, 6, 987Ϫ993.
E. Hey, P. B. Hitchcock, M. F. Lappert, A. K. Rai, J. Or-
ganomet. Chem. 1987, 325, 1Ϫ12.
[22]
[4] [4a]
T. Kremer, F. Hampel, F. A. Knoch, W. Bauer, A. Schmidt,
P. Gabold, M. Schütz, J. Ellermann, P. von Rague-Schleyer, Or-
[23]
[24]
Siemens Analytical Instruments, SAINT, Version 4.1, 1994.
Siemens Analytical Instruments, SHELXTL, Version 5.1, 1996.
Received July 26, 1999
[4b]
ganometallics 1996, 15, 4776Ϫ4782. Ϫ
E. W. Bauer, M.
Schitz, F. W. Heinemann, M. Moll, Z. Anorg. Allg. Chem. 1998,
629, 547Ϫ566.
[I99270]
2368
Eur. J. Inorg. Chem. 1999, 2355Ϫ2368