Synthesis of blue imino(pentafluorophenyl)phosphane

Article abstract of DOI:10.1021/ic200623x

The reaction of AgC₆F₅ with monomeric iminophosphanes of Mes*-N=P-X (X = Cl, I) in CH₂Cl₂ at ambient temperature gives imino(pentafluorophenyl)phosphane, Mes*N=P(C ₆F₅) (1), in almost quantitative yield (96%), which could be isolated as a highly viscous blue oil. The same reaction with LiC ₆F₅ results in the formation of imino(amino)phosphane (C₆F₅)₂P-N(Mes*)-P=NMes* (2) (yield 93%). In the second series of experiments the analogous reaction of MC ₆F₅ (M = Ag, Li) with dimeric [Cl-P(μ-N-Dipp)] ₂ was studied, leading to the formation of [R-P(μ-N-Dipp)] ₂ (R = C₆F₅) (3) for M = Ag, while only decomposition products such as P(C₆F₅)₃ were observed in the reaction with the Li salt. Highly labile Mes*-N=P-C ₆F₅ (1) decomposes at ambient temperatures, forming among other products the diphosphane (C₆F₅)₂P- P(C₆F₅)₂ (4). Reaction of 1 with Fe ₂(CO)₉ yields the iron carbonyl complexes Mes*-N=P(C₆F₅)?Fe(CO)₄ (5) and [Mes*-N=P(C₆F₅)]₂?Fe(CO) ₃ (6). The structure, bonding, and potential energy surface are discussed on the basis of B3LYP/6-31G(d,p) computations. According to time-dependent B3LYP calculations, the blue color of 1 arises from an n → π* electronic transition.

Full text of DOI:10.1021/ic200623x

ARTICLE
pubs.acs.org/IC
Synthesis of Blue Imino(pentafluorophenyl)phosphane
Marcus Kuprat,† Mathias Lehmann,† Axel Schulz,*,†,‡ and Alexander Villinger†
†Universit€at Rostock Institut f€ur Chemie, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
‡Leibniz-Institut f€ur Katalyse e.V. an der Universit€at Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
S Supporting Information
b
ABSTRACT: The reaction of AgC6F5 with monomeric iminophosphanes of Mes*ꢀNdPꢀX (X = Cl,
I) in CH2Cl2 at ambient temperature gives imino(pentafluorophenyl)phosphane, Mes*NdP(C6F5)
(1), in almost quantitative yield (96%), which could be isolated as a highly viscous blue oil. The same
reaction with LiC6F5 results in the formation of imino(amino)phosphane (C6F5)2PꢀN(Mes*)ꢀPdNMes*
(2) (yield 93%). In the second series of experiments the analogous reaction of MC6F5 (M = Ag, Li) with
dimeric [ClꢀP(μ-NꢀDipp)]2 was studied, leading to the formation of [RꢀP(μ-NꢀDipp)]2 (R =
C6F5) (3) for M = Ag, while only decomposition products such as P(C6F5)3 were observed in the
reaction with the Li salt. Highly labile Mes*ꢀNdPꢀC6F5 (1) decomposes at ambient temperatures,
forming among other products the diphosphane (C6F5)2PꢀP(C6F5)2 (4). Reaction of 1 with Fe2(CO)9
yields the iron carbonyl complexes Mes*ꢀNdP(C6F5) Fe(CO)4 (5) and[Mes*ꢀNdP(C6F5)]2 Fe(CO)3
3
3
(6). The structure, bonding, and potential energy surface are discussed on the basis of B3LYP/6-31G(d,
p) computations. According to time-dependent B3LYP calculations, the blue color of 1 arises from an
n f π* electronic transition.
’ INTRODUCTION
iminophosphane compounds containing the pentafluorophenyl
group.8e Herein, we report on the synthesis of pentafluorophenyl-
substituted iminophosphanes and their iron carbonyl complexes.
The low coordination number chemistry of phosphorusꢀnitro-
gen compounds was extensively developed over the last four
decades thanks to the use of bulky groups.1,2 It has been possible
to characterize these reactive PN species due to their kinetic and
thermodynamic stabilization by appropriate substitution.
’ RESULTS AND DISCUSSION
It was not until 1973 that Flick and Niecke were able to isolate
a phosphorus(III)ꢀnitrogen compound with the structural
feature of a phosphazene, ꢀPdNꢀ.3 This first iminophosphane,
a phosphazene with phosphorus in coordination number two,
was yielded from the reaction of bis(trimethylsilyl)aminodi-
fluorophosphane with lithiumꢀbis(trimethylsilyl)amide (eq 1)
Synthesis. Monomeric iminophosphanes of the type RꢀNd
PꢀX (X = halogen) are only known for R = Mes*. Thus, it was of
interest to study if it is possible to substitute the halogen X by the
formal pseudohalogen pentafluorophenyl. The halogen/C6F5
substitution was attempted by means of the silver and the lithium
C6F5 salts, MC6F5 (M = Ag, Li), as illustrated in Scheme 2.
Surprisingly, only the reaction of AgC6F5 in CH2Cl2 at RT gives
the desired product Mes*ꢀNdPꢀC6F5 (1) in almost quantita-
tive yield (96%), while 1,1-bis(pentafluorophenyl)-2,4-bis(2,4,6-
tri-tert-butylphenyl)-1,3-diphospha-2,4-diazene,
ðMe3SiÞ2NꢀPF2 þ LiNðSiMe3Þ2 f
ðMe3SiÞ2NꢀPdNꢀSiMe3 þ LiF þ Me3SiꢀF ð1Þ
Monomeric halogeno(imino)phosphanes, RꢀNdPꢀX (X =
halogen), have been isolated only for derivatives involving the
bulky Mes* (Mes* = 2,4,6-tri-tert-butylphenyl) substituent at
nitrogen,4 which imposes a relative destabilization of the corre-
sponding dimer due to substituent steric strain.5 Slightly smaller
substituents attached at the nitrogen atom such as the Dipp
group (Dipp = 2,6 diisopropylphenyl) lead to 1,3-dihalogeno-
cyclo-1,3-diphospha-2,4-diazanes.6 The electronic and kinetic
reasons for this RꢀNdPꢀX/[ClP(μ-NR)]2 dimerization pro-
cess have been addressed recently.7 Furthermore, it is known that
electron-rich iminophosphanes of the type RꢀNdPꢀR (R =
aryl, alkyl) can dimerize in a [2 þ 1] cycloaddition (Scheme 1).
Today, compounds bearing NP bonds are extensively studied
inorganic species,2ꢀ5,8 and a vast body of structural and spectro-
scopic data is available. However, much less is known about
(C6F5)2PꢀN(Mes*)ꢀPdNꢀMes* (2), was obtained in the re-
action of LiC6F5 with Mes*ꢀNdPꢀCl in diethyl ether (yield
93%). While the synthesis of 1 can be carried out at ambient
temperatures, in the case of 2, the reaction was carried out at
ꢀ80 °C and then slowly warmed to ambient temperatures over a
period of 1 h. Obviously, the Lewis-acidic metal center plays an
important role. Since the silver iodide and chloride, respectively,
are sparingly soluble in contrast to lithium chloride, it can be
assumed that formation of 2 is mediated by solvated Liþ species.
In a second series of experiments we studied the anal-
ogous reaction of MC6F5 (M = Ag, Li) with dimeric [ClꢀP(μ-
NꢀDipp)]2 (3Cl) in order to investigate if there are also
Received: March 26, 2011
Published: May 25, 2011
r
2011 American Chemical Society
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Inorganic Chemistry
ARTICLE
Scheme 1. Different Channels for the Dimerization of R1ꢀNdPꢀR2
Scheme 2. Reaction of Mes*ꢀNdPꢀX with MC6F5 (M = Ag,
Li)
Figure 1. HOMO and LUMO in 1.
Table 1. 31P NMR Data (chemical shift in ppm) and Selected
Structural Data (distances in Angstroms, angles in degrees) of
Amino(imino)phosphanes of the Type R1R2NꢀPdNꢀMes*,a
Scheme 3. Reaction of [ClꢀP(μ-NꢀDipp)]2 with AgC6F5
1, 2, Mes*ꢀNdPꢀCl, and Mes*NPþAlCl4
ꢀ
R1, R2
PdN
PNC
31P shift
H, Mes*d
Me3Si, Me3Sid
iPr, iPrd
1.573(8)
1.566(2)
1.555(2)
1.538(3)
1.552(5)
1.556(5)
126.1(7)
117.6(2)
129.6(2)
140.7(4)
125.9(4)
122.7(5)
272
327
268
203
194
Me, Med
different reaction channels for the Cl/C6F5 substitution depend-
ing on the used metal. Indeed, two different reaction pathways
weredetected too. Whilethereaction withthesilversalt inCH2Cl2
at ꢀ80 °C yielded the expected 1,3-bis(pentafluorophenyl)-2,4-
bis(2,6-di-isopropylphenyl)-cyclo-1,3-diphospha-2,4-diazene
[DippNP(C6F5)]2 (3) (yield 65%, Scheme 3), only decomposi-
tion products such as P(C6F5)3, characterized by X-ray structure
elucidation, were obtained from the reaction with LiC6F5 in
diethyl ether at ꢀ80 °C, which is followed by a slow warming up.
Even better yields for 3 and less side products are obtained
when the iodine species, [IꢀP(μ-NꢀDipp)]2 (3I), is used.
Moreover, the halogen/C6F5 substitution is much faster when
the iodine species is utilized. To the best of our knowledge
[DippNP(C6F5)]2 (3) has not been described yet.
Mes*ꢀNdPꢀCp* (trans)d
tBuꢀNdPꢀMes*d
Mes*ꢀNdPꢀ Bud
490
363
11.5, 290
218
153
139
87
t
1b
1.565
153.2
2
1.541(2)
1.480(3)
1.499(6)
1.506(2)
133.6(2)
172.5(3)
161.0(6)
146.7(2)
Mes*ꢀNdPꢀId
Mes*ꢀNdPꢀBrd
Mes*ꢀNdPꢀClc
Mes*ꢀNdPꢀFd
Mes*NPþAlCl4
1.475(8)
177.0(7)
79
ꢀc
a Taken from ref 11. b Calculated values at the B3LYP/6-31G(d,p) level
of theory. c Taken from ref 4 or 12. d Taken from ref 2.
Properties and Characterization. Mes*ꢀNdPꢀC6F5 (1)
can be isolated as a highly viscous, deep blue liquid in contrast to
2, which is an orange crystalline solid. The blue color is rather
unusual taking into account that the vast majority of PN species
are either yellow or red colored but has already been observed by
Burford et al. for a solution of in-situ-prepared Mes*ꢀNdPꢀC6H5
in CH2Cl2.9 The UVꢀvis spectrum of the deep blue CH2Cl2
solution of 1 exhibits one very weak characteristic n f π*
electronic transition at 592 nm (besides strong π f π*
electronic transitions in the range <380 nm), which could be
assigned on the basis of TD-B3LYP calculation (Tables S11,
see Supporting Information). The blue color arises from
the weak n f π* HOMOꢀLUMO electronic transition
(Figure 1). The HOMO describes a delocalized mainly
nonbonding molecular orbital with large coefficients along
the CꢀNꢀPꢀC unit, while the LUMO displays an antibond-
ing PN π* bond.
Furthermore, 1 was characterized by elemental analysis, Raman/
IR, and NMR spectroscopy as well as mass spectrometry
(ESI-TOF/MS: 457 [Mes*ꢀNdPꢀC6F5]þ). The 31P NMR
spectrum of 1 displayed one singlet resonance at δ = 361.6, which
is shifted to low field compared to the two resonances found for
2, which are observed at δ = 11.49 (m, PNP) and 290.15 (d,
31
2J(31Pꢀ P) = 6.7 Hz, NPN), respectively. For comparison, the
31P NMR shift of Mes*ꢀPdNꢀCl is found at δ = 139 and for
[Mes*ꢀNtP]þ at δ = 79.4 31P NMR data of several PN species
are summarized in Table 1. From these data it can be concluded
that the 31P NMR resonance is observed at low field the more
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Inorganic Chemistry
ARTICLE
Scheme 4. Synthesis of 4
Table 2. Calculated Selected Structural Data of trans-1, cis-1,
2, and Dimers of 1
CN
NP
PC
CNP
NPC
CNPC
trans-1
cis-1
2
1.370
1.397
1.410
1.472
1.565
1.552
1.568
1.756
1.780
1.772
1.763
1.764
1.774
1.757
1.763
1.764
1.768
1.903
1.905
1.862
1.893
153.2
148.2
111.5
124.9
131.9
119.6
119.6
134.9
135.3
122.3
122.9
138.2
138.8
103.8
113.9
104.4
110.2
180.0
0.3
ꢀ22.3
85.9
trans-dimer
cis-dimer
1.437
1.437
1.899
1.900
102.3
102.8
106.4
107.2
104.8
106.8
108.2
110.1
ꢀ46.1
ꢀ113.4
48.6
112.4
ꢀ74.8
ꢀ77.0
61.3
1.444
1.451
1.918
1.920
88.4
crystallography. Diphosphane (C6F5)2PꢀP(C6F5)2, which is easily
prepared from the reaction of (C6F5)2PBr with mercury or
magnesium, has already been reported,10 but so far, its structural
data have not been published yet.
Since it was impossible to obtain crystals of 1 suitable for
single-crystal structure elucidation (even at low temperature), 1
was reacted with Fe2(CO)9 to obtain ironꢀcarbonyl adducts.
The iron carbonyl adduct formation reaction is straightforward
and can easily be followed by 31P NMR experiments. Upon
addition of a solution of 1 in n-hexane to a stirred suspension of
Fe2(CO)9 in n-hexane at ꢀ50 °C, an immediate reaction
occurred leading to a brown suspension (Scheme 4). The
suspension was slowly warmed to ambient temperatures. Filtra-
tion gave a dark red solution from which after concentration
black crystals of Fe3(CO)12 were obtained. Decantation of the
supernatant, further concentration, and storage at ambient tem-
perature gave red crystals of N-(2,4,6-tri-tert-butylphenyl)imino-
(pentafluorophenyl)phosphane iron tetracarbonyl adduct,
Mes*NP(C6F5) Fe(CO)4 (5), which could be isolated in good
3
yields (82%). It should be mentioned that [Mes*NP(C6F5)]2
3
Fe(CO)3 (6) was observed whennoexcess of Fe2(CO)9 was used.
Power et al. frequently used iron carbonyl complexes to
stabilize elementꢀelement double bonds, e.g., diphosphenes,
RPdPR.13 For example, the reaction of Na2Fe(CO)4 with
different bulky monosubstituted phosphorus(III) halides RPCl2,
where R = 2,4,6-Me3C6H2, CH2SiMe3, CH(SiMe3)2, N-
(SiMe3)2, ꢀOC6H2-2,6-tBu2-4-Me, or ꢀOC6H2-2,4,6-tBu3
yielded products in which the phosphorus center behaves as
either a diphosphene or a bridging phosphinidene group. Com-
plexes 5 and 6 are rare examples of iron carbonyl complexes
featuring an iminophosphane as ligand.
Figure 2. Relative Gibbs energies for the isomers of [Mes*NP(C6F5)]y
(y = 1, 2). The exact values are given in parentheses.
electron rich the PN unit is and vice versa (cf. RꢀNdPꢀX; X = I,
210; Br, 153; Cl, 139; F, 87; [RNP]þ = 79 ppm; R = Mes*).
In contrast to 2, which is thermally stable at ambient temperatures
(Mp 123 °C), compound 1 is thermally labile, moisture sensitive,
but stable under argon atmosphere over a long period at low
temperatures (ꢀ80 °C) as a solid but slowly decomposes in benzene
solution. Both compounds (1 and 2) can be prepared in bulk. This
together with the very good solubility in common organic solvents
makes both compounds good precursors for further synthesis.
Slow decomposition of 1 is already observed at ambient
temperatures. Thermal treatment of 1 up to 102 °C in vacuum
(10ꢀ3mbar) led to a fast decomposition yielding a yellow oil. Among
the decomposition products diphosphane (C6F5)2PꢀP(C6F5)2
(4) could be isolated and characterized by X-ray single
Computations. Inspection of the conformational space at the
B3LYP/6-31G(d,p) level of theory displayed two different
monomeric structures for 1 (Figure 2): (i) a cis isomer (cis-1)
and (ii) a trans arrangement (trans-1) with respect to the
CMes*ꢀNdPꢀCC6F5 moiety. Our calculation revealed that the
transꢀcis energy gap is rather small, with the trans form being the
most stable isomer (ΔEtot(cisꢀtrans) = þ0.1 kcal/mol, ΔG298
-
(cisꢀtrans) = 0.8 kcal/mol). Different dimerization processes
must be considered. As shown in Figure 2, four different dimers
were found: (i) a cyclic imino(amino)phosphane (2) with
NPNP connectivity and a diphosphene1a,14 with a NPPN
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Table 3. Crystallographic Details of 2, 3Cl, 3I, and 3
2
3Cl
3I
3
chemical formula
C
48.98H59.96Cl1.96F10N2P2
C30H40Cl2N2P2
561.48
C24H34I2N2P2
C60H58F10N2P2
1059.02
yellow
fw [g molꢀ1
]
998.13
orange
monoclinic
P21/n
color
colorless
orthorhombic
P212121
9.8933(3)
18.1268(6)
35.2455(11)
90.00
yellow
triclinic
Pꢀ1
9.0746(3)
9.2454(3)
9.5949(4)
67.447(2)
83.782(2)
70.667(2)
701.35(4)
1
cryst syst
space group
a [Å]
triclinic
Pꢀ1
18.2786(7)
10.6517(4)
26.1221(10)
90.00
10.1554(4)
11.7132(4)
12.2055(5)
108.513(2)
100.009(2)
93.573(2)
1345.01(9)
1
b [Å]
c [Å]
R [deg]
β [deg]
γ [deg]
V [Å3]
Z
99.774(2)
90.00
90.00
90.00
5012.1(3)
4
6320.7(3)
8
F
calcd [g cmꢀ3
μ [mmꢀ1
MoKR [Å]
T [K]
]
1.323
1.180
1.577
1.307
]
0.264
0.327
2.369
0.156
λ
0.71073
173(2)
44 100
11 440
8501
0.71073
173(2)
76 995
0.71073
173(2)
22 552
4931
0.71073
173(2)
39 880
measured reflns
independent reflns
reflns with I > 2σ(I)
Rint.
15 223
8513
11 583
4108
6517
0.0463
2085
0.0692
0.0227
328
0.0315
F(000)
2384
552
R1 (R [F2 > 2σ(F2)])
wR2 (F2)
0.0562
0.1445
1.057
0.0445
0.0262
0.0672
1.055
0.0434
0.0888
0.1193
GooF
1.003
1.050
parameters
655
665
159
338
connectivity and (ii) two isomers for cyclo-diphosphadiazane
besides a high-lying three-membered NPP heterocycle bearing
orbital population (NAO) net charges are q = þ0.14 (CMes*),
ꢀ0.85 (N), þ0.96 (P), and ꢀ0.49 e (CC6F5) and alternate along
the CMes*ꢀNꢀPꢀCC6F5 unit. Charge comparison of the PN
unit in 1 with neutral PN (q(P) = þ0.77, q(N) = ꢀ0.77e) shows
a charge transfer of only 0.10e, although the entire Mes* group
donates 0.41 electrons of which, however, 0.30 electrons are
accepted by the C6F5 group, describing a formal classic
pushꢀpull situation.2
P
III and PV atoms. In agreement with experiment, all computed
dimerization processes are endergonic (e.g., ΔG298(2 ꢀ 2 ꢁ
trans-1) = þ16.1 kcal/mol). It should be noted that at least
dimerization to 2 represents an exothermic process (ΔG298(2 ꢀ
2 ꢁ trans-1) = ꢀ3.3 kcal/mol, see Table S10 in the Supporting
Information).
Since it was impossible to obtain experimental structural data for
1, its structure was calculated for the gas phase at the B3LYP level of
theory. Selected structural data of trans-1 and cis-1 along with data
of different dimers are summarized in Table 2. The most interesting
structural features of aryl-substituted iminophosphanes are the
short PN double bond and rather large CNP angles. While for
trans-1 and cis-1 the PN distances of 1.555 and 1.552 Å, respec-
tively, arefairly similarandinthe expected range(cf.Σrcov(PdN) =
1.52 Å),15 the CMes*ꢀN distance in trans-1 (1.370 Å) is signifi-
cantly shorter compared to that in cis-1 (1.397 Å). Since for both
species the CNPC unit is planar and allows delocalization of the 6π
aryl electrons, the computed difference in the CN bond can be
attributed to a larger steric strain in cis-1. In both species the C6F5
ring adopts a perpendicular position to the Mes* ring.
X-ray Crystallography. The structures of compounds 2ꢀ6
have been determined. Tables 3 and 4 present the X-ray crystallo-
graphic data. Selected molecular parameters are listed in
Figures 3ꢀ8. X-ray quality crystals of all considered species were
selected in Kel-F-oil (Riedel deHaen) or Fomblin YR-1800 (Alfa
Aesar) at ambient temperatures. All samples were cooled to
ꢀ100(2) °C during the measurement.
Mes*NdPꢀN(Mes*)ꢀP(C6F5)2 (2) crystallizes in the tricli-
nic space group P-1 with two formula units per cell. The structure
consists of separated Mes*NdPꢀN(Mes*)ꢀP(C6F5)2 and tri-
ply disordered CH2Cl2 molecules with no significant intermole-
cular contacts. In contrast to the trigonal pyramidal P2 atom,
both nitrogen atoms and the dicoordinated P1 atom sit in a
trigonal planar environment with a PN double bond of 1.541(2) Å
(P1ꢀN1) and two PN single bonds of 1.726(2) (P1ꢀN2)
and 1.740(2) Å (P2ꢀN2), respectively, which lies in the ex-
pected range for amino(imino)phosphanes, for example, PdN
1.545(6) Å and PꢀN 1.632(6) Å in MeN(H)ꢀPdNꢀMes*
(Σrcov(PꢀN) = 1.76 Å and Σrcov(PdN) = 1.52 Å).2,10,13
Since the phenyl ring of the Mes* group attached to N1 lies
orthogonal to the plane composed of N1, P1, N2, and P2 there is
MO and NBO16 calculations for 1 displayed highly polarized
PꢀN and PꢀC bonds. While for the PꢀC bond only 31% of the
NBO electron density is localized at the P atom, for the PꢀN
σ bond this value is further decreased to 24% but increased for
the π bond to 39%. The hybrid orbital at the P atom used for the
PꢀC bond possesses 12% s atomic orbital character, which
increases to 17% in the PꢀN bond. The calculated natural atomic
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Inorganic Chemistry
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Table 4. Crystallographic Details of 4, 5, and 6
4
5
6
chemical formula
C24F20P2
730.18
colorless
tetragonal
P-421c
12.9649(16) 8.6162(3)
12.9649(16) 10.4409(3)
42.228(12) 17.9784(6)
90.00
90.00
90.00
7098(2)
12
2.050
0.359
0.71073
173(2)
19 726
5223
C28H29F5FeNO4P C51H58F10FeN2O3P2
fw [g molꢀ1
color
]
625.34
red
1054.78
red
cryst syst
space group
a [Å]
b [Å]
c [Å]
R [deg]
β [deg]
γ [deg]
V [Å3]
Z
triclinic
P-1
monoclinic
P21/n
20.3424(6)
22.6247(7)
24.7584(8)
90.00
112.2600(10)
90.00
93.508(2)
98.424(2)
113.3970(10)
1455.60(8)
2
10545.6(6)
8
F
calcd [g cmꢀ3
μ [mmꢀ1
MoKR [Å]
T [K]
]
1.427
1.329
]
0.639
0.424
λ
0.71073
173(2)
48 927
10 458
8133
0.71073
173(2)
77 741
18 565
9788
Figure 3. ORTEP drawing of the molecular structure of 2 in the crystal.
Thermal ellipsoids with 50% probability at 173 K (hydrogen atoms
omitted for clarity). Selected bond lengths (Å) and angles (deg):
P1ꢀN1 1.541(2), P1ꢀN2 1.726(2), P2ꢀN2 1.740(2), P2ꢀC43
1.846(2), P2ꢀC37 1.872(2), N1ꢀC1 1.419(3), N2ꢀC19 1.473(3);
N1ꢀP1ꢀN2 108.47(9), N2ꢀP2ꢀC43 104.09(9), N2ꢀP2ꢀC37
109.61(9), C43ꢀP2ꢀC37101.1(1), C1ꢀN1ꢀP1 133.6(2), C19ꢀN2ꢀP1
111.5(1), C19ꢀN2ꢀP2 125.8(1), P1ꢀN2ꢀP2 120.7(1), N1ꢀC1ꢀC6
117.0(2), N1ꢀC1ꢀC2 124.2(2), C38ꢀC37ꢀP2 128.6(2),
C42ꢀC37ꢀP2 115.6(2), C48ꢀC43ꢀP2 128.5(2), C44ꢀC43ꢀP2
115.9(2), N2ꢀP1ꢀN1ꢀC1 ꢀ174.1(2), N1ꢀP1ꢀN2ꢀC19 178.5(1),
N1ꢀP1ꢀN2ꢀP2 13.6(2).
measured reflns
independent reflns
reflns with I > 2σ(I) 3834
Rint.
F(000)
0.0542
4248
0.0331
644
0.0339
0.0958
1.049
0.1054
4384
0.0520
0.1101
0.919
R1 (R [F2 > 2σ(F2)]) 0.0486
wR2 (F2)
GooF
0.1045
1.073
622
parameters
401
1320
no interaction between the PN π bond and the π system of the
phenyl ring (Figure 3). A look along the N1, P1, N2, and P2 unit
displays a cis conformation and an almost planar arrangement of
all four atoms (N1ꢀP1ꢀN2ꢀP2 13.6(2)°). While a rather small
angle is found around the dicoordinated P1 atom (N1ꢀP1ꢀN2
108.47(9)°), due to steric repulsion the angle around
the dicoordinated N1 atom is fairly large with 133.6(2)°
(C1ꢀN1ꢀP1).
Mes*NP(C6F5) Fe(CO)4 (5) crystallizes in the space group
3
P1 with two molecules per unit cell. The perspective view of the
complex is illustrated in Figure 4. The primary coordination
sphere consists of an iron-centered trigonal bipyramidal arrange-
ment of the four CO ligands and the trans-Mes*ꢀNdPꢀC6F5
ligands (CaxisꢀFeꢀC/Pplane angles between 89.8° and 91.4°,
axis: C28ꢀFeꢀC25 178.19(5), trigonal plane: C27ꢀFeꢀC26
115.08(7)°, C27ꢀFeꢀP 122.33(5)°, C26ꢀFeꢀP 122.58(5)°).
Seven CO FꢀC intermolecular interactions with three dif-
3 3 3
ferent Mes*ꢀNdPꢀ(C6F5) ligands are observed besides nu-
merous CꢀF HꢀC contacts. The O F distances between
3 3 3
3 3 3
3 3 3
3 3 3
2.802(1) (O1 F20) and 3.000(2) Å (O1 F30), respectively,
Figure 4. ORTEP drawing of the molecular structure of 5 in the crystal.
Thermal ellipsoids with 50% probability at 173 K (hydrogen atoms
omitted for clarity). Selected bond lengths (Å) and angles (deg): PꢀN
1.558(1), PꢀC19 1.825(1), PꢀFe 2.1225(3), NꢀC1 1.417(1),
FeꢀC28 1.803(1), FeꢀC27 1.804(1), FeꢀC26 1.812(1), FeꢀC25
1.819(1), O1ꢀC25 1.130(2), O2ꢀC26 1.135(2), O3ꢀC27 1.141(2),
O4ꢀC28 1.134(2); NꢀPꢀC19 101.66(5), NꢀPꢀFe 138.80(4),
C19ꢀPꢀFe 119.52(4), C1ꢀNꢀP 125.47(8), C28ꢀFeꢀC27 90.09(6),
C28ꢀFeꢀC26 90.32(6), C27ꢀFeꢀC26 115.08(7), C28ꢀFeꢀC25
178.19(5), C27ꢀFeꢀC25 89.78(6), C26ꢀFeꢀC25 91.38(5), C28ꢀ
FeꢀP 88.84(4), C27ꢀFeꢀP 122.33(5), C26ꢀFeꢀP 122.58(5),
C25ꢀFeꢀP 89.71(4), C19ꢀPꢀNꢀC1 177.23(9).
lie within the range of weak F O van der Waals interactions
3 3 3
(cf. ΣrvdW(FꢀO) = 3.0 Å).13 Due to these van der Waals
interactions, in the crystal the iron complexes are arranged in
such a manner that stacked chains of alternating polar “Fe-
(CO)4-units” and nonpolar “Mes*-units” are formed.
The Mes*ꢀNdPꢀC6F5 ligand is part of the trigonal plane
and attached to the iron atom via the phosphorus with a FeꢀP
bond length of 2.1225(3) Å (cf. 2.232 (l) Å in the diphosphene
iron carbonyl complex (CO)4FeꢀP(R)dP(R)ꢀFe(CO)4,
R = N(SiMe3)2).17 The PꢀN distance in 2 (1.558(1) Å) is
found in the range expected for the free ligand (calculated value
for the gas-phase species 1.565 Å, in Mes*NdPꢀN(Mes*)ꢀP-
(C6F5)2 (2) 1.541(2) Å). This is probably due to the fact that the
HOMO (Figure 1) represents a nonbonding molecular orbital
with a large coefficient at the P atom. Thus, this MO describes
mainly the lone pair localized at the P atom in the Lewis picture.
The steric effects of binding Fe(CO)4 to the Mes*ꢀNdPꢀC6F5
species in 4 is reflected in the position (trigonal plane) and
orientation of the Mes* and C6F5 aryl rings. Both rings and the
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Figure 5. ORTEP drawing of the molecular structure of 6 in the crystal.
Thermal ellipsoids with 50% probability at 173 K (hydrogen atoms
omitted for clarity). Selected bond lengths (Å) and angles (deg):
Fe1ꢀC49 1.803(4), Fe1ꢀC51 1.816(4), Fe1ꢀC50 1.819(4), Fe1ꢀP1
2.133(1), Fe1ꢀP2 2.134(1), P1ꢀN2 1.562(3), P1ꢀC19 1.833(3),
P2ꢀN1 1.566(3), P2ꢀC43 1.830(3), N1ꢀC25 1.419(4), N2ꢀC1
1.425(4); C49ꢀFe1ꢀC51 92.9(2), C49ꢀFe1ꢀC50 93.8(2), C51ꢀFe1ꢀ
C50 173.3(2), C49ꢀFe1ꢀP1 111.9(1), C51ꢀFe1ꢀP1 87.1(1),
C50ꢀFe1ꢀP1 89.6(1), C49ꢀFe1ꢀP2 110.1(1), C51ꢀFe1ꢀP2
91.9(1), C50ꢀFe1ꢀP2 86.6(1), P1ꢀFe1ꢀP2 137.98(4), N2ꢀP1ꢀC19
101.5(2), N2ꢀP1ꢀFe1 137.5(1), C19ꢀP1ꢀFe1 120.9(1), N1ꢀP2ꢀ43
101.9(2), N1ꢀP2ꢀFe1 138.1(1), C43ꢀP2ꢀFe1 119.8(1), C25ꢀN1ꢀP2
121.3(2).
Figure 7. ORTEP drawing of the molecular structure of 3 in the crystal.
Thermal ellipsoids with 50% probability at 173 K (hydrogen atoms
omitted for clarity). Selected bond lengths (Å) and angles (deg ): P1—
N1 1.7204(9), P1—N1i 1.7225(9), P1—C13 1.874(1), P1—P1i
2.6173(5), N1—C1 1.427(1), N1—P1i 1.7225(9), N1—P1—N1i
81.04(4), N1—P1—C13 105.09(5), P1—N1—P1i 98.96(4). Symme-
try codes: (0) 1 ꢀ x, 1 ꢀ y, 1 ꢀ z.
Figure 8. ORTEP drawing of the molecular structure of 3I in the
crystal. Thermal ellipsoids with 50% probability at 173 K (hydrogen
atoms omitted for clarity). Selected bond lengths (Å) and angles (deg):
P1—N1 1.697(1), P1—N1i 1.714(1), P1—P1i 2.5894(8), N1—C1
1.430(2), N1—P1—N1i 81.19(6), N1—P1—I1 104.38(5), N1i—P1—
I1 103.83(5), P1—N1—P1i 98.81(6). Symmetry codes: (0) 1 ꢀ x, 1 ꢀ y,
1 ꢀ z.
Figure 6. ORTEP drawing of the molecular structure of 4 in the crystal.
Thermal ellipsoids with 50% probability at 173 K (hydrogen atoms
omitted for clarity). Selected bond lengths (Å) and angles (deg):
P1ꢀC7 1.848(6), P1ꢀC1 1.868(6), P1ꢀP1i 2.248(3); C7ꢀP1ꢀC1
99.9(3), C7ꢀP1ꢀP1i 102.8(2), C1ꢀP1ꢀP1i 95.0(2). Symmetry codes:
(0) ꢀx, ꢀy þ 1, z.
178.8(3)° and C25ꢀN1ꢀP2ꢀC43 177.0(2)°). (iv) Both
PN bond lengths (P2ꢀN1 1.566(3) Å, P1ꢀN2 1.562(3) Å)
are found in the expected range for a typical double bond
(cf. Σrcov(PdN) = 1.52 Å).
almost planar C1ꢀNꢀPꢀC19 unit (C19ꢀPꢀNꢀC1 177.23(9)°)
are oriented parallel to the Fe(CO)4 fragment.
[Mes*NP(C6F5)]2 Fe(CO)3 (6) crystallizes in the monocli-
3
nic space group P21/n with eight formula units (two independent
Diphosphane (C6F5)2PꢀP(C6F5)2 (4) crystallizes in the
tetragonal space group P-421c with 12 formula units per cell
(three independent molecules). The structure consists of
separated (C6F5)2PꢀP(C6F5)2 molecules with no significant
intermolecular contacts. The main feature of interest is the
PꢀP distance of 2.248(3) Å, which is slightly longer than the
sum of the covalent radii 2.2 Å. This slight increase is expected
in view of the electronegative C6F5 moiety reducing the
electron density in the bonding orbitals of the PꢀP unit. Both
PR2 fragments adopt a C2-symmetric staggered configuration
to each other.
molecules) per cell. In contrast to 2, only one CO FꢀC
3 3 3
intermolecular interaction is observed (2.713(3) Å). With re-
spect to bond lengths and angles similar structural features are
found for the tricarbonyl iron complex 6 in comparison to the
tetracarbonyl iron complex 5: (i) The molecular structure also
displays a slightly distorted trigonal bipyramidal iron center with
the two Mes*ꢀNdPꢀC6F5 ligands occupying a position in the
trigonal plane. (ii) Both Mesꢀ*NdPꢀC6F5 ligands are attached
via the P atom (Fe1ꢀP1 2.133(1) Å, Fe1ꢀP2 2.134(1) Å).
(iii) The Mes*ꢀNdPꢀC6F5 ligands adopt a trans configuration
with an almost planar CꢀPꢀNꢀC unit (C19ꢀP1ꢀN2ꢀC1
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Four-membered rings of the type [XꢀP(μ-NR)]2 containing
alternating phosphorus(III) and nitrogen centers are known as
cyclo-1,3-diphospha(III)-2,4-diazanes (X = halogen, R = organic
group).6,18,19 Cyclo-diphospha(III)-diazane [ClꢀP(μ-NDipp)]2
was first generated by Burford et al. in the reaction of PCl3 with
DippNH2.20Structural data of [XꢀP(μ-NR)]2 (X = I and C6F5,
R = organic substitutent) have not been published to date. While
compounds 3 and 3I crystallize in the triclinic space group P-1
with one molecule per unit cell, for 3Cl the orthorhombic space
group P21212119 was found. Noteworthy, both 3 and 3Cl crystal-
lize with four and eight benzene molecules per unit cell, while no
solvent is found for 3I.
The solvent is removed in vacuo, and the residue is extracted with n-
hexane (10 mL) and filtered. Removal of solvent and drying in vacuo yields
for X = Cl 0.256 g (0.559 mmol, 82%) and for X = I 0.299 g (0.653 mmol,
96%) of N-(2,4,6-tri-tert-butylphenyl)imino(pentafluorophenyl)phos-
phane Mes*NP(C6F5) (1) as a blue oil.
Decomposition at 102 °C. Anal. Calcd (found) for C24H29F5NP
1
(457.46): C, 63.01 (61.23); H, 6.39 (5.98); N, 3.06 (2.98). H NMR
(25 °C, CD2Cl2, 300.13 MHz): δ = 1.35 (s, 9 H, p-C(CH3)3), 1.37 (s, 18
1
H, o-C(CH3)3), 7.41 (d, 2 H, 5J(31Pꢀ H) = 7.41 Hz, m-CH). 13C{1H}
5
13
NMR (25 °C, CD2Cl2, 75.48 MHz): δ = 32.53 (d, J(31Pꢀ C) =
13
2.8 Hz, o-C(CH3)3), 33.63 (d, 7J(31Pꢀ C) = 4.7 Hz p-C(CH3)3), 35.21
(s, p-C(CH3)3), 36.60 (s, o-C(CH3)3), 122.52 (s, m-CH), 133.83 (aryl-C),
19
19
138.2 (dm, 1J(13Cꢀ F) = 257 Hz, aryl-CF), 144.6 (dm, 1J(13Cꢀ F) =
The molecular structures of 3 and 3I (Figures 7 and 8)
display trans-substituted centrosymmetric dimers with a pla-
nar P2N2 core protected by two bulky Dipp groups. The
metrical parameters of the P2N2 core such as the NꢀPꢀN0
and PꢀNꢀP0 angles (NPN0 = 81.0ꢀ81.5°; PNP0 = 97.5ꢀ
99.0°) do not change in 3, 3Cl, and 3I and are in the same
range found for [XꢀP(μ-NR)]2 (X = halogen, R = organic
substituent).19 Two slightly different PꢀN bond lengths
between 1.697(1) and 1.7225(9) Å are found in the expected
range for a typical single bond (cf. Σrcov(PꢀN) = 1.76 Å). The
260 Hz, aryl-CF), 145.65 (aryl-C), 147.4 (dm, 1J(13Cꢀ F) = 250 Hz,
19
aryl-CF), 149.16 (aryl-C). 31P{1H} NMR (25 °C, CD2Cl2, 121.51 MHz):
δ = 361.6. 19F{1H} NMR (25 °C, CD2Cl2, 282.38 MHz): δ = ꢀ160.4
(m, m-CF), ꢀ147.3 (m, p-CF), ꢀ136.5 (m, o-CF). MS (EI, m/z,
(>10%)): 41 (11), 57 (33), 69 (18), 77 (10), 110 (12), 198 (27)
[(C6F5)P]þ, 246 (80) [Mes*H]þ, 261 (36) [Mes*NH]þ, 290 (100)
[Mes*NP]þ, 366 (18) [(C6F5)2PH]þ, 493 (14), 550 (10). MS (ESI-
TOF/MS): 262 [Mes*NH2]þ, 457 [Mes*NP(C6F5)]þ. UVꢀvis:
592 nm.
Synthesis of 1,1-Bis(pentafluorophenyl)-2,4-bis(2,4,6-
tri-tert-butylphenyl)-1,3-diphospha-2,4-diazene (C6F5)2PN-
(Mes*)PNMes* (2). To a stirred solution of C6F5Br (0.247 g,
1.0 mmol) in Et2O (10 mL) n-BuLi (2.5 M, 0.4 mL, 1.0 mmol) is
added dropwise at ꢀ80 °C over a period of 15 min. The solution of
LiC6F5 is added quickly to a solution of Mes*NPCl (0.326 g, 1.0 mmol)
in Et2O (5 mL) at ꢀ80 °C by means of a PTFE tubing, resulting in a
yellow suspension. After warming to ambient temperatures, the solvent
is removed in vacuo and the residue is extracted with n-hexane (10 mL).
Removal of solvent and drying in vacuo yields 0.427 g (0.467 mmol,
93.4%) of 1,1-bis(pentafluorophenyl)-2,4-bis(2,4,6-tri-tert-butylphenyl)-
1,3-diphospha-2,4-diazene (C6F5)2PN(Mes*)PNMes* (2) asanorangesolid.
Mp 123 °C. Anal. Calcd (found) for C48H58F10N2P2 (914.92): C,
63.01 (62.99); H, 6.39 (6.81); N, 3.06 (2.82). 1H NMR (25 °C, CD2Cl2,
300.13 MHz): δ = 1.25 (s, 18 H, C(CH3)3), 1.33 (s, 18 H, C(CH3)3),
1.37 (s, 18 H, C(CH3)3), 7.33 (s, 2 H, m-CH), 7.42 (s, 2 H, m-CH).
13C{1H} NMR (25 °C, CD2Cl2, 125.77 MHz): δ = 31.35 (s, p-
C(CH3)3), 31.88 (s, p-C(CH3)3), 32.72 (s, o-C(CH3)3), 35.03 (s, p-
C(CH3)3), 35.21 (s, p-C(CH3)3), 36.14 (s, o-C(CH3)3), 36.99 (s, o-
P
P distances between 2.56 and 2.62 Å are slightly longer
3 3 3
than the sum of the covalent radii (2.20 Å) but significantly
shorter than the sum of the van der Waals radii (3.8 Å).13
Thus, strong van der Waals interactions across the ring can be
assumed.
’ CONCLUSION
Imino(pentafluorophenyl)phosphane, Mes*NdP(C6F5), was
obtained in the reaction of AgC6F5 with monomeric iminopho-
sphanes of Mes*ꢀNdPꢀX (X = Cl, I). In contrast to the
halogen-substituted Mes*ꢀNdPꢀX, which are orange solids,
Mes*NdP(C6F5) is a highly viscous blue oil (decomposition at
102 °C). The blue color arises from the weak n f π* HOMO
ꢀLUMO electronic transition, with both MOs mainly localized
along the PN unit.
A totally different reaction channel is observed when
LiC6F5 was used instead of the silver salt, leading to formation
of (C6F5)2PꢀN(Mes*)ꢀPdNꢀMes*. When the Dipp sub-
stitutent was used instead of Mes*, again two different final
products were isolated depending on the used metal in MC6F5
(M = Li, Ag). Dimeric [C6F5ꢀP(μ-NꢀDipp)]2 (R = C6F5)
was isolated with AgC6F5. As expected, the Dipp substituent
provides less steric strain which is not compensated by a
strong pushꢀpull system caused by the C6F5/Mes* substitu-
ents. Hence, only the dimer [C6F5ꢀP(μ-NꢀDipp)]2 is ob-
served, in contrast to monomeric Mes*NdP(C6F5), in accord
with theory.
1
13
C(CH3)3), 39.30 (s, o-C(CH3)3), 111.3 (dm, J(31Pꢀ C) = 71 Hz,
CP), 123.05 (s, m-CH), 127.27 (s, m-CH), 136.86 (aryl-C), 138.2 (dm,
19
13
1J(13Cꢀ F) = 255 Hz, aryl-CF), 141.90 (m, 2J(31Pꢀ C) = 12 Hz, aryl-
CN(P)P), 143.58 (aryl-C), 143.9 (dm, 1J(13Cꢀ F) = 257 Hz, aryl-CF),
19
149.0 (dm, J(13Cꢀ F) = 249 Hz, aryl-CF), 150.05 (aryl-C), 150.48
1
19
(aryl-C). 31P{1H} NMR (25 °C, CD2Cl2, 121.51 MHz): δ = 11.5 (m,
PNPN), 290.2 (d, 2J(31Pꢀ P) = 6.7 Hz, PNPN). 19F{1H} NMR
31
(25 °C, CD2Cl2, 282.38 MHz): δ = ꢀ161.4 (m, m-CF), ꢀ148.6
(m, p-CF), ꢀ120.8 (m, o-CF). MS (EI, m/z, (>10%)): 57 (69), 246
(60), 247 (11), 259 (12), 261 (18), 290 (31) [Mes*NP]þ, 402 (97), 403
(30), 418 (100), 442 (17), 457 (56) [Mes*NP(C6F5)]þ, 475 (12), 652
(14), 912 (10) [M ꢀ 2H]þ. UVꢀvis: 432.02 nm.
Reaction of Mes*NdP(C6F5) with Fe2(CO)9 yields the
hitherto unknown iron carbonyl complexes Mes*ꢀNdP-
(C6F5) Fe(CO)4 and [Mes*ꢀNdP(C6F5)]2 Fe(CO)3.
Crystals suitable for X-ray crystallographic analysis were obtained by
cooling a saturated dichloromethane solution of 2 to ꢀ25 °C over a
period of 10 h.
3
3
’ EXPERIMENTAL DETAILS
Synthesis of 1,3-Diiodo-2,4-bis(2,6-di-isopropylphenyl)-
cyclo-1,3-diphospha-2,4-diazane (3I). To a stirred solution of
1,3-dichloro-2,4-bis(2,6-di-isopropylphenyl)-cyclo-1,3-diphospha-2,4-
diazane (1.45 g, 3.0 mmol) in CH2Cl2 (15 mL) a solution of trimethyl-
silyl iodide (1.20 g, 6.0 mmol) in CH2Cl2 (10 mL) is added dropwise at
ambient temperatures over a period of 30 min and stirred for 3 days.
NMR studies show that just two-thirds of the dichloro-cyclo-diphospha-
diazane is converted to the corresponding cyclo-diiodo compound. For
Synthesis of N-(2,4,6-Tri-tert-butylphenyl)imino(penta-
fluorophenyl)phosphane Mes*NP(C6F5) (1). To a stirred solu-
tion of Mes*NPX (X = Cl 0.160 g, 0.68 mmol, X = I 0.284 g,
0.68 mmol) in CH2Cl2 (5 mL) a suspension of AgC6F5 (0.192 g,
0.70 mmol) in CH2Cl2 (7 mL) is added dropwise at ꢀ80 °C over a
period of 20 min. The resulting dark blue suspension is stirred for 10 min
and then slowly warmed to ambient temperatures over a period of 1 h.
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quick further conversion sodium iodide (0.45 g, 3.0 mmol) is added.
Extraction with n-hexane and separation of P2I4 by fractional crystal-
lization yields 1.74 g (2.61 mmol, 87%) of 1,3-diiodo-2,4-bis(2,6-di-
isopropylphenyl)-1,3-diphospha-2,4-diazane as a yellowish crystalline
solid.
Mp 103 °C (dec.). Anal. Calcd (found) for C28H29F5FeNO4P
1
(625.34): C, 53.78 (53.74); H, 4.67 (4.55); N, 2.24 (2.14). H NMR
(25 °C, CD2Cl2, 300.13 MHz): δ = 1.28 (s, 9 H, p-C(CH3)3), 1.43 (s, 18
1
H, o-C(CH3)3), 7.32 (d, 2 H, 5J(31Pꢀ H) = 2.5 Hz, m-CH). 13C{1H}
NMR (25 °C, CD2Cl2, 75.48 MHz): δ = 31.74 (s, p-C(CH3)3), 32.05 (s,
6
13
Mp 186 °C (dec.). Anal. Calcd (found) for C24H34I2N2P2 (666.30):
o-C(CH3)3), 35.12 (d, J(31Pꢀ C) = 1.1 Hz, p-C(CH3)3), 36.64 (d,
13
13
4J(31Pꢀ C) = 1.9 Hz, o-C(CH3)3), 122.99 (d, 4J(31Pꢀ C) = 4.7 Hz,
1
C, 43.26 (44.12); H, 5.14 (5.21); N, 4.20 (4.21). H NMR (25 °C,
m-CH), 138.00 (aryl-C), 146.23 (aryl-C), 208.93 (d, J(31Pꢀ C) =
9.9 Hz, CO). 31P{1H} NMR (25 °C, CD2Cl2, 121.51 MHz): δ = 300.6.
19F{1H} NMR (25 °C, CD2Cl2, 282.38 MHz): δ = ꢀ159.1 (m, m-CF),
ꢀ148.6 (m, p-CF), ꢀ132.8 (m, o-CF). MS (EI, m/z, (>10%)): 41 (13),
57 (37), 246 (18) [Mes*]þ, 260 (11), 290 (25) [Mes*NP]þ, 297 (11),
313 (18), 315 (43), 440 (13), 513 (100) [Mes*NP(Fe)C6F5]þ, 541
(17) [Mes*NP(FeCO)C6F5]þ, 625 (10) [M]þ.
2
13
1
CDCl3, 300.13 MHz): δ = 1.34 (d, 24 H, 3J(1Hꢀ H) = 6.75 Hz,
CH(CH3)2), 3.83 (sept, 4 H, J(1Hꢀ P) = 2.27 Hz, CH(CH3)2),
5
31
1
1
3J(1Hꢀ H) = 6.80 Hz, CH(CH3)2), 7.19 (d, 4 H, 3J(1Hꢀ H) = 7.50 Hz,
(m-CH)), 7.30 (t, 2H, 3J(1Hꢀ H) = 7.61 Hz, (p-CH)). 13C{1H} NMR
1
(25 °C, CDCl3, 75.47 MHz): δ = 26.54 (s, CH(CH3)2), 29.27 (s,
CH(CH3)2), 124.92 (m-CH), 129.05 (s, p-CH), 130.33 (t, 3J(13Cꢀ P) =
31
6.57 Hz, o-C), 149.5 (m, broad, ipso-C). 31P{1H} NMR (25 °C, CDCl3,
121.49 MHz): δ = 265.0 (s). MS (CIþ, isobutane): 667 [M þ H]þ, 539
[M ꢀ I]þ, 206 [DippNP]þ.
Crystals suitable for X-ray crystallographic analysis were obtained by
storage of a saturated n-hexane solution of 5 at ambient temperature
for 10 h.
Crystals suitable for X-ray crystallographic analysis were obtained by
storage of a saturated n-hexane solution of 3I at ambient temperatures
for 10 h.
’ ASSOCIATED CONTENT
Synthesis of 1,3-Bis(pentafluorophenyl)-2,4-bis(2,6-di-
isopropylphenyl)-cyclo-1,3-diphospha-2,4-diazane [DippNP-
(C6F5)]2 (3). To a stirred solution of [DippNPX]2 (X = Cl 0.242 g,
0.5 mmol; X = I 0.333 g, 0.5 mmol) in CH2Cl2 (5 mL) a suspension of
AgC6F5 (0.275 g, 1.0 mmol) in CH2Cl2 (15 mL) is added dropwise at
ꢀ80 °C over a period of 20 min. The resulting brownish solution is
slowly warmed to ambient temperatures and stirred for three hours
resulting in a yellow suspension. The solvent is removed in vacuo and the
residue is extracted with n-hexane (10 mL) and filtered. Removal of
solvent and drying in vacuo yields for X = Cl 0.244 g (0.327 mmol, 65%)
and for X = I 0.284 g (0.381 mmol, 76%) of 1,3-bis(pentafluorophenyl)-
2,4-bis(2,6-di-isopropylphenyl)-cyclo-1,3-diphospha-2,4-diazane [DippNP-
(C6F5)]2 (3) as yellow crystals.
S
Supporting Information. This material is available free of
b
charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: axel.schulz@uni-rostock.de.
’ ACKNOWLEDGMENT
We are indepted to Dr. D. Michalik and J. Thomas (University
of Rostock). Generous support by the University of Rostock is
gratefully acknowledged. We would like to thank the Deutsche
Forschungsgemeinschaft (SCHU 1170/4-1) for financial support.
Mp 133 °C. Anal. Calcd (found) for C36H34F10N2P2 (746.60):
C, 57.91 (57.81); H, 4.59 (4.72); N, 3.75 (3.50).1H NMR (25 °C, CD2Cl2,
1
300.13 MHz): δ = 1.08 (d, 12 H, 3J(1Hꢀ H) = 6.66 Hz, CH(CH3)2),
1
1.18 (d, 12 H, 3J(1Hꢀ H) = 6.80 Hz, CH(CH3)2), 3.91 (septm, 4 H,
1
1
5J(31Pꢀ H) = 2.27 Hz, CH(CH3)2), 3J(1Hꢀ H) = 6.80 Hz, CH-
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5791
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