Phosphinohydrazines and phosphinohydrazides M(-N(R)-N(R) -PPh2)n of some transition and main group metals: Synthesis and characterization. Rearrangement of Ph2 P-NR-NR- ligands into aminoiminophosphorane, RN=PPh2-NR-, and related chemistry

Article abstract of DOI:10.1016/j.jorganchem.2004.06.056

The reactions of phosphinohydrazines ArNH-N(Ar)-PPh₂ {Ar = Ph (2a), p-Bu^t-C₆H_4- (2b)} with metal silylamides M[N(SiMe₃)₂]_n, {M = Fe(II), Fe(III), Co(II), Ni(I), Cu(I)} or the reactions of lithium salts ArN(Li)-N(Ar)-PPh₂ with metal halides (GeCl₂, ZnCl₂, FeBr₂, CoCl₂, NiBr₂, CrCl₃, MnCl₂) are strongly dependent on nature of a metal and its ligand environment. Early transition metals or non-transition metals form stable phosphinohydrazides M[N(Ar)N(Ar)PPh₂]_n {M = Li, Zn, Ge(II), Mn(II), Cr(III), Fe(II)}. Starting ligand 2a and germylene Ge(NPhNPhPPh₂)₂ (7) were characterized by X-ray analysis. Germanium is coordinated additionally with a phosphorus atom of one of the diphenylphosphine groups.The distance Ge?P was found to be 2.563(1) ?. This coordination leads to an appreciable increase in a pyramidal geometry of nitrogen atoms relatively to a non-coordinated fragment.Late transition metals (Co, Ni, Cu) and metals with enhanced oxidation state (Fe³⁺) cause transformation of a phosphinohydrazide ligand.For Co(II), Ni(II), Fe(III) this leads quantitatively to aminoiminophosphoranates M(NAr-PPh₂NAr) _n. Complex Co[N(C₆H₄Bu^t) -PPh₂ = N-C₆H₄Bu^t] ₂ (11) was characterized by X-ray analysis. Nickel(I) silylamide, (Ph₃P)₂NiN(SiMe₃) ₂, being reacted with 2a yields azobenzene complex, (Ph₃P)₂Ni(PhN = NPh), while copper(I) silylamide originally forms (PhNH-NPh-PPh₂)₂ CuN(SiMe₃)₂ (18). Heating of the latter in toluene solution yields insoluble copper(I) diphenylphosphide, azobenzene, 2a and hexamethyldisilazane. The reaction of hydrazobenzene with Ph₂PCl (1:1) in methylene chloride for three days gives aminoiminophosphorane dihydrochloride[PhNH-PPh₂NPh]· 2HCl (3) in quantitative yield.

Full text of DOI:10.1016/j.jorganchem.2004.06.056

Journal of Organometallic Chemistry 689 (2004) 3060–3074
www.elsevier.com/locate/jorganchem
Phosphinohydrazines and phosphinohydrazides
M(–N(R)–N(R)–PPh2)n of some transition and main group
metals: synthesis and characterization
Rearrangement of Ph2P–NR–NR– ligands into
aminoiminophosphorane, RN‚PPh2–NR–, and related chemistry
a
a,
a
a
Yana V. Fedotova , Alexander N. Kornev *, Vyacheslav V. Sushev , Yurii A. Kursky ,
a
Tatiana G. Mushtina , Natalia P. Makarenko , Georgy K. Fukin ,
a
a
a
Gleb A. Abakumov , Lev N. Zakharov , Arnold L. Rheingold
b
b
a
Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 Tropinin Street, 603950 Nizhny Novgorod, Russia
b
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
Received 19 March 2004; accepted 29 June 2004
Available online 6 August 2004
Abstract
The reactions of phosphinohydrazines ArNH–N(Ar)–PPh2 {Ar = Ph (2a), p-But–C6H4– (2b)} with metal silylamides M[N(Si-
Me3)2]n, {M = Fe(II), Fe(III), Co(II), Ni(I), Cu(I)} or the reactions of lithium salts ArN(Li)–N(Ar)–PPh2 with metal halides (GeCl2,
ZnCl2, FeBr2, CoCl2, NiBr2, CrCl3, MnCl2) are strongly dependent on nature of a metal and its ligand environment. Early transition
metals or non-transition metals form stable phosphinohydrazides M[N(Ar)N(Ar)PPh2]n {M = Li, Zn, Ge(II), Mn(II), Cr(III),
Fe(II)}. Starting ligand 2a and germylene Ge(NPhNPhPPh2)2 (7) were characterized by X-ray analysis. Germanium is coordinated
˚
additionally with a phosphorus atom of one of the diphenylphosphine groups. The distance Geꢀ ꢀ ꢀP was found to be 2.563(1) A. This
coordination leads to an appreciable increase in a pyramidal geometry of nitrogen atoms relatively to a non-coordinated fragment.
Late transition metals (Co, Ni, Cu) and metals with enhanced oxidation state (Fe3+) cause transformation of a phosphinohydrazide
ligand. For Co(II), Ni(II), Fe(III) this leads quantitatively to aminoiminophosphoranates M(NAr–PPh2‚NAr)n. Complex Co[N
(C6H4But)–PPh2‚N–C6H4But]2 (11) was characterized by X-ray analysis. Nickel(I) silylamide, (Ph3P)2NiN(SiMe3)2, being reacted
with 2a yields azobenzene complex, (Ph3P)2Ni(PhN‚NPh), while copper(I) silylamide originally forms (PhNH–NPh–PPh2)2CuN
(SiMe3)2 (18). Heating of the latter in toluene solution yields insoluble copper(I) diphenylphosphide, azobenzene, 2a and hexameth-
yldisilazane. The reaction of hydrazobenzene with Ph2PCl (1:1) in methylene chloride for three days gives aminoiminophosphorane
dihydrochloride [PhNH–PPh2‚NPh] Æ 2HCl (3) inquantitative yield.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Transition metal complexes; Phosphazanes; Phosphinoamides; Phosphinohydrazines; Amidoimidophosphoranes; Germylenes; X-ray
diffraction
1. Introduction
In spite of great variety of known neutral ambiden-
tate (P, N)-ligands, our knowledge on the ligands of
*
Corresponding author. Tel.: +78312-12-66-52; fax: +78312-12-74-
97.
E-mail address: akornev@imoc.sinn.ru (A.N. Kornev).
type I, containing r-bonded nitrogen and terminal
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.06.056

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3061
phosphorus(III) atoms are rather poor. In part this is
2. Results and discussion
due to low availability of starting compounds. Mean-
while, the coordination chemistry of such ligands is an
area of increasing interest owing to their versatile
behavior depending on metal nature. Here phospho-
rus, which has a predisposition for combination with
soft metals (i.e. late transition metals or metals in
low oxidation states), is juxtaposed with a hard nitro-
gen center (which is predisposed to combination with
early transition metals or metals in high oxidation
states).
2.1. Phosphinohydrazines ArNH–NAr–PPh2 {Ar = Ph
(2a), p-But–C6H4– (2b)}
Diphenylphosphino-1,2-diarylhydrazines (aryl = Ph
(2a), p-But–C6H4– (2b)) were synthesized from corre-
sponding nitrobenzenes in three steps (Eqs. (1) and
(2)). Hydrazobenzene 1a is a well-known compound
[5], while 1,2-di(p-tert-butylphenyl)hydrazine 1b has
been synthesized for the first time. The reduction of p-
tert-butylnitrobenzene with the zinc powder gave white
crystalline 1b in a good yield. The substance, however,
is significantly more sensitive to oxygen than
hydrazobenzene.
R'
R'
P
M-transition or non-transitionmetal;
E- nonmetal
R
E
M(L)
n
Zn=NaOH
!
N
R
L- concomitant ligand
Ar–NO2
Ar–NH–NH–Ar
1
H2O=C3H7OH
ð1Þ
I
Ar ¼ Ph ð1aÞ; p-But–C6H4– ð1bÞ
Monolithium derivatives of hydrazoarenes were pre-
pared in situ by the reaction of butyllithium with an
equivalent of the corresponding diaryhydrazine. Subse-
quent treatment with chlorodiphenylphosphine affords
desirable hydrazophosphines 2a, 2b:
Phosphinohydrazines of types II–IV, being consid-
ered as ligands in organometallic and
R
R' P
R
R
R
2
N
N
N
N
Ph PCl
2
BuLi
Ar-N(Li)-NH-Ar
Ar-NH-NH-Ar
PR'2
R
' P
R' P
2
2
-LiCl
III
II
ð2Þ
Ar-N-NH-Ar
2a Ar = Ph,
R"
N
R
N
t
2b Ar= p-Bu -C6H4-
Ph P
2
2
R
N
R
PR'2
PR'2
N
Large colorless crystals of 2a and 2b were obtained by
crystallization from abs. ethanol. The compounds do
not prone to alcoholysis at room temperature. 31P
NMR chemical shifts of compounds 2a and 2b at room
temperature were found to be +63.62 and +62.9 ppm,
respectively. Crystals of 2a are fairly stable to oxygen;
solution of 2a in CCl4 remains unchangeable for three
days judging by 31P NMR spectrum.
R
IV
V
coordination chemistry, possess unusual properties
dependent on (1) partial double bonding between phos-
phorus and nitrogen; (2) relative weakness of P–N and
N–N bonds. The stability and reactivity of the com-
plexes containing phosphinohydrazine ligands are often
determined by nature of a metal atom and its environ-
ment. The known transition metal complexes with lig-
ands of the types II (R = Me, Et; R0 = Cl, Ph, OPh,
CH2Ph) [1–3]; III and IV (R = Me, R0 = Ph, R00 = Me,
H) [4] include mono-P or bidentate P,P0-coordination
to a metal. There are no sufficient evidences for a
P,N-chelation in the complexes with ligands of type
II–IV [4]. Apparently this is due to a strong interaction
between phosphorus and nitrogen making the phos-
phorus centers more basic. The metal complexes con-
taining single-charged ligands of type V are still
unknown.
2.2. Structural investigations of 2a
Crystal data and some details of the data collection
and refinement for 2a are given in Table 1. Selected
bond distances and angles for 2a are given in Table 2.
The molecular structure of 2a with the atom numbering
scheme is shown in Fig. 1. Each nitrogen atom in diph-
enylphosphino-1,2-diphenylhydrazine (2a) has a slightly
distorted planar-trigonal environment. The sums of the
angles are 356.16ꢁ and 358.13ꢁ at the N(1) and N(2)
atoms, respectively. The P–N and N–N distances are
˚
1.7280(13) and 1.4008(18) A, respectively, as expected.
The goals of our investigation include the preparation
and study of g2[P, r-N]-bonded phosphinohydrazides of
various metals as well as the investigation of phos-
phinohydrazines 2a, 2b as ligand precursors.
It was found that crystals of 2a (as well as 2b) ob-
tained from different solvents have various positions of
the NH band in IR-spectra. Product 2a, prepared by
slow crystallization from abs. ethanol, shows a single

Table 1
Summary of crystal and refinement data for complexes
Ph2P–NPh–N(Ph)H (2a)
{Ge(NPh–NPh–PPh2)2}(C4H8O2) (7)
[ButC6H4N‚Ph2P–NC6H4But]2Co Æ (C7H8) (11)
(Ph3P)2Ni(PhN‚NPh) (13)
Empirical formula
Formula weight
Temperature (K)
C
368.40
24H21N2P
C52H48N4P2GeO2
895.45
243(2)
C71H80CoN4P2
1110.26
293
C48H40N2NiP2
765.47
223(2)
0.71073
Triclinic
100(2) K
0.71073
˚
Wavelength (A)
0.71073
Monoclinic
P21/c
0.71073
Monoclinic
C2/c
Crystal system
Space group
Unit cell dimensions
Monoclinic
C2/c
ꢀ
P1
˚
a (A)
9.9509(14)
10.1626(16)
11.3099(17)
95.902(3)
95.893(3)
118.851(2)
981.1(3)
9.5505(10)
25.345(3)
18.926(2)
90
30.906(5)
21.514(3)
21.509(3)
90
14.6589(9)
13.6712(8)
18.8730(11)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
96.959(2)
90
111.094(3)
90
94.401(1)
90
c (ꢁ)ꢁ3
˚
V A
4547.4(8)
4
1.308
13343(3)
8
1.105
3771.1(4)
4
1.348
Z
2
1.247
Dcalc (Mg/m3)
Absorption coefficient (mmꢁ1
Crystal size (mm3)
Reflections collected
)
0.151
0.30 · 0.20 · 0.10
5162
0.789
0.346
0.25 · 0.25 · 0.10
31167
0.637
0.15 · 0.15 · 0.15
11835
0.30 · 0.30 · 0.10
26815
8921 [0.0374]
Independent reflections [Rint
Reflection with I > 2r(I)
Absorption correction
]
2807 [0.0200]
2501
8733 [0.0600]
6071
4423 [=0.0253]
3918
Semi-empirical from
equivalents,
SADABS
1.000/0.945
Semi-empirical from
equivalents,
SADABS
Semi-empirical from
equivalents,
SADABS
1.000/0.707
Semi-empirical from
equivalents,
SADABS
1.000/0.872
Maximum/minimum
transmission
0.925/0.798
Refinement method
Data/restraints/parameters
R indices [I > 2r(I)]
R indices (all data)
Largest difference peak
Full-matrix least-squares on F2
2807/0/328
Full-matrix least-squares on F2
8921/12/604
Full-matrix least-squares on F2
8733/0/640
Full-matrix least-squares on F2
4423/0/320
R1 = 0.0310, wR2 = 0.0879
R1 = 0.0352, wR2 = 0.0925
0.203 and ꢁ0.180
R1 = 0.0522, wR2 = 0.1320
R1 = 0.0781, wR2 = 0.1414
0.794 and ꢁ0.267
R1 = 0.0939, wR2 = 0.2474
R1 = 0.1203, wR2 = 0.2660
1.746 and ꢁ0.509
R1 = 0.0367, wR2 = 0.0901
R1 = 0.0422, wR2 = 0.0932
0.533 and ꢁ0.231
ꢁ3
˚
and hole (e A
)

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3063
Table 2
Ph
Ph
N
˚
Selected bond lengths (A) and angles (ꢁ) for 2a
N
P(1)–N(2)
P(1)–C(13)
P(1)–C(19)
N(1)–C(1)
N(1)–N(2)
N(1)–H(1)
N(2)–C(7)
1.7280(13)
1.8266(16)
1.8318(17)
1.395(2)
Ph
Ph
N
H
P
N
H
P
1.4008(18)
0.83(2)
1.419(2)
A
B
Ph
N
Ph
N
N(2)–P(1)–C(13)
N(2)–P(1)–C(19)
C(13)–P(1)–C(19)
C(1)–N(1)–N(2)
C(1)–N(1)–H(1)
N(2)–N(1)–H(1)
N(1)–N(2)–C(7)
N(1)–N(2)–P(1)
C(7)–N(2)–P(1)
100.50(7)
102.05(7)
102.00(7)
120.46(13)
119(1)
H
H
N
P
N
P
Ph
Ph
117(1)
114.81(12)
120.58(10)
122.74(10)
D
C
Our attempts to prepare 2a in another way, using
Et3N as dehydrochlorinating agent, were unsuccessful.
Unexpectedly, hydrazobenzene in ether, toluene or
methylene chloride solutions does not react with Ph2PCl
in the presence of Et3N.
+ [Et NH]Cl
Ph P-NPh-NPhH
PhNH-NHPh + Ph PCl + Et N //
3
2
2
3
ð3Þ
Starting reagents were separated from the reaction mix-
ture after 3 h of contact. We found, however, another
interaction between hydrazobenzene and Ph2PCl in
methylene chloride without Et3N. When an equimolar
mixture of the reactants was allowed to stand for three
days at 20 ꢁC, the color of solution steadily turned or-
ange then the solution becames colorless. Finally, an
abundant white crystalline precipitate was formed.
According to the element analysis, IR and NMR spectra
we characterized this substance as amidoimidophospho-
rane dihydrochloride [PhNH–PPh2‚NPh] Æ 2HCl (3).
The yield of 3 was found to be ꢂ100%. No other prod-
ucts were observed. We had no purposes in mechanistic
investigation of such an interesting interaction; note,
however, that methylene chloride acts not only as a sol-
vent, but as a reactant, since product 3 contains two
chlorine atoms per mole while the yield of 3 is quantita-
tive. So, we have found conditions for the PNN!NPN
rearrangement. Eq. (4) does not explain however the ex-
act mechanism of this reaction.
Fig. 1. Molecular structure of Ph2P–N(Ph)–N(Ph)H (2a).
NH band at 3300 cmꢁ1. The same product prepared by
fast crystallization from i-propanol shows two bands: at
3300 and 3320 cmꢁ1. The solutions of these products in
dichloromethane show a sharp absorption peak at 3380
cmꢁ1. Such behavior of 2a is in a good agreement with
the properties of previously studied diphosphinohydra-
zine F2P–NMe–NMe–PF2 [6], showing a temperature
dependent 19F NMR spectrum, suggesting large tor-
sional barriers about the P–N and N–N bonds. On this
basis, diphenylphosphino-1,2-diarylhydrazines with
essentially planar nitrogen environments may adopt sev-
eral conformations (A–D); the found structure of 2a
corresponds to conformation A.
+
PhNH-NHPh + Ph PCl
2
Ph-NH
NHPh
-
Ph P
2
Cl
ð4Þ
CH Cl
2
2
.
[Ph-NH-PPh =NPh] 2HCl
2
3
Dihydrochloride 3 forms pure free base PhNH–
PPh2‚NPh (4) after washing with aqueous NH3 or
NaOH. Compound 4 shows very strong absorption at

3064
Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
1300 cmꢁ1 assigned to stretching vibrations of P‚N
double bond [7]. Interestingly, 4 shows a single reso-
nance at ꢁ4.12 ppm in the 31P NMR spectrum at 20
ꢁC while the HPLC analysis shows two peaks of equal
intensity, probably attributed to two isomers 4a and 4b.
We explored another method synthesizing of 5a, by the
reaction of dilithium-1,2-diphenylhydrazide with one
equivalent of chlorodiphenylphosphine, however this
way lead to essential quantities of byproducts. By this
reason the direct synthesis of bis(diphenylphospino)-
1,2-diphenylhydrazine also was unsuccessful.
Ph
Ph
Ph
Ph
Ph
2.4. Germanium (II) phosphinohydrazide, {Ge(NPh–
NPh–PPh2)2}(dioxane) (7)
P=N
P=N
Ph-N
Ph
Ph-N
4a
H
H
4b
Lappert type germylenes Ge(NR2)2 (R = Me3Si, al-
kyl, aryl) are quite stable compounds [10–12] widely
used as monodentate ligands in coordination and
organometallic chemistry [13]. At the same time, the
carbenoids GeR2, whose substituent R contains addi-
tional chelating functions, are few in number but at-
tract considerable interest [14]. In particular, such
compounds can be used as convenient ligands in coor-
dination and organometallic chemistry due to their
versatile co-ordination properties depending on the
r-donor and p-acceptor activity of the Ge(II), M
and D centers.
Therefore, reaction (4) can be considered as a novel ap-
proach to aromatic aminoiminophosphoranes [8,9].
Compounds2a, 2barethermallystableuptillto140ꢁC.
Above this temperature the crystals of 2a decompose to
form azobenzene and the mixture of phosphorus-contain-
ing products. The main product, aminoiminophospho-
rane, H–N(Ph)–PPh2‚NPh (4), which is the structural
isomer of 2a, was identified by 31P NMR and HPLC.
Ph-N-NH-Ph
Ph P
o
140 C
Ph-N=N-Ph (50%) +
2a
2
ð5Þ
D
+ H-NPh-Ph P=NPh (37%) + ....
2
4
Ge
ML
+
n
The crystals of 2b decompose similarly giving presuma-
bly substituted azobenzene and H–N(Ar)–PPh2‚NAr
(Ar = t-BuC6H3–) (tentative suggestion).
D
-L
-nL
-nL
D
M
D
2.3. Lithium phosphinohydrazides
D
D
D
Ge
Ge
(L)M
Ge
M
The treatment of 2a and 2b with butyllithium yields
pale yellow solutions which after concentrating gave vis-
cous oil. The study of NMR spectra of 5a in C6D6 shows
D
7
a Li resonance at d = ꢁ2.88 (s) ppm, and a 31P reso-
D - donor atom (P, N, O)
nance at 55.00 (s) ppm. Absence of the 7Li–31P coupling
suggests that there is no strong Li–P interaction in ben-
zene solution. The NMR spectrum of 5a in C6D6 does
not change for two months. An addition of small
amounts of ether to toluene solutions of 2a and 2b af-
fords colorless fine crystalline solids of their lithium salts
6a and 6b, respectively.
The interaction of lithium phosphinohydrazide 6a
with GeCl2(dioxane) in THF immediately gives an or-
ange-red solution. The change of THF by toluene causes
precipitation of LiCl. The latter was filtered off while the
solution was concentrated and the final product was
formed as a yellow powder (7) from diethyl ether.
Ar-N-N-Ar
Ar-N-NH-Ar
n-BuLi
PhMe
GeCl2ðdioxÞ þ 2Ph2P–NPh–NPh–Li
! GeðNPh–NPh–PPh2Þ þ2LiCl þ diox
Li
Ph P
Ph P
2
2
2
ð7Þ
5
2
7
The compound shows solvatochromic effect. While the
color of 7 in THF is orange-red, the toluene or diethyl
ether solutions have pale yellow coloring. Germylene 7
can be easily purified by re-crystallization from warm
ether solution. However, the crystals suitable for X-ray
analysis were obtained from the dioxane/toluene (1:1)
mixture.
5a, 6a, Ar = Ph;
5b, 6b, Ar= p-But-C H -
ð6Þ
6 4
Ar-N-N-Ar
Et O
2
Li(Et O)
2
Ph P
2
6

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3065
Table 3
Bond lengths (A) and angles (ꢁ) for Ge(NPhNPh–PPh2)2 (7)
˚
Ge(1)–N(3)
Ge(1)–N(1)
Ge(1)–P(1)
P(1)–N(2)
P(2)–N(4)
N(1)–N(2)
N(3)–N(4)
N(3)–C(25)
N(2)–C(7)
N(4)–C(31)
1.895(2)
1.997(2)
2.5630(7)
1.699(2)
1.753(2)
1.454(3)
1.380(3)
1.428(3)
1.436(3)
1.421(3)
N(3)–Ge(1)–N(1)
N(3)–Ge(1)–P(1)
N(1)–Ge(1)–P(1)
N(2)–P(1)–C(19)
N(2)–P(1)–C(13)
C(19)–P(1)–C(13)
N(2)–P(1)–Ge(1)
N(4)–P(2)–C(43)
N(4)–P(2)–C(37)
C(43)–P(2)–C(37)
C(1)–N(1)–N(2)
C(1)–N(1)–Ge(1)
N(2)–N(1)–Ge(1)
C(7)–N(2)–N(1)
C(7)–N(2)–P(1)
N(1)–N(2)–P(1)
N(4)–N(3)–C(25)
N(4)–N(3)–Ge(1)
C(25)–N(3)–Ge(1)
N(3)–N(4)–C(31)
N(3)–N(4)–P(2)
C(31)–N(4)–P(2)
C(6)–C(1)–C(2)
C(6)–C(1)–N(1)
C(2)–C(1)–N(1)
103.40(9)
107.80(6)
65.67(6)
108.08(11)
108.63(11)
108.08(12)
79.43(7)
Fig. 2. Molecular structure of [Ge(NPhNPh–PPh2)2] Æ (C4H8O2) (7).
The H atoms and solvent molecule are omitted for clarity.
102.79(10)
103.73(11)
100.22(11)
114.08(19)
113.56(15)
107.62(13)
117.79(19)
123.30(16)
105.69(14)
115.14(19)
109.96(15)
133.46(16)
118.00(18)
121.63(15)
119.06(17)
117.5(2)
cant changes in its geometry as compared with the
non-coordinated fragment. The Ge(1)–N(1) and N(1)–
˚
N(2) distances (1.997(2) and 1.454(3) A, respectively)
are noticeably longer than the analogous Ge(1)–N(3)
˚
˚
(1.895(2) A) and N(3)–N(4) (1.380(3) A) distances in
the non-coordinated ligand. The N(1)–N(2) bond
length in 1 is also longer than the nitrogen–nitrogen
bond in phosphinohydrazine Ph2P–N(Ph)–N(Ph)H
˚
(1.401(2) A), while the N(2)–P(1) distance (1.699(2)
˚
A) and the N(1)N(2)P(1) angle (105.69(14)ꢁ) are much
less than the N(4)–P(2) bond length (1.753(2) A) and
˚
the N(3)N(4)P(2) angle (121.63(15)ꢁ) in the non-coordi-
nated fragment.
Four-membered cycle Ge-N(1)–N(2)–P(1) is flat, the
125.8(2)
116.6(2)
˚
atoms being on average 0.067 A out of this plane. It is
of interest that the N(1) and N(2) atoms of this cycle
possess a pyramidal geometry in contrast to the N(3),
N(4) atoms. The deviations of the N(1), N(2) atoms
from the planes of the Ge(1)N(2)C(1) and
2.5. Structural description of 7
The crystal data and some details of the data collec-
tion and refinement for 7 are given in Table 1. Selected
bond distances and angles for 7 are in Table 3. Draw-
ing of the molecular structure of 7 with the atom num-
bering scheme is shown in Fig. 2. The crystal structure
consists of discrete molecules of 7 and a disordered
dioxane molecule which has no shortened contacts with
7 and may be considered as a solvation molecule. The
Ge(1) atom is coordinated to two N atoms and the
P(1) atom of one of the diphenylphosphine groups.
˚
N(1)P(1)C(7) fragments are 0.46 and 0.32 A, respec-
tively, while the analogous deviations of the N(3) and
N(4)
atoms
from
the
Ge(1)N(4)C(25)
and
˚
N(3)P(2)C(31) planes are 0.11 and 0.10 A. The sums
of angles at the N(1) and N(2) are 335ꢁ and 347ꢁ, respec-
tively, while these sums for the N(3) and N(4) atoms
were found to be 359ꢁ. The literature data indicate that
the pyramidal geometry of N(1) and N(2) found in 7 is
unusual, because the nitrogen atoms in phosphazanes
[17] and phosphoranates [18] as well as germanium (II)
amidinate Ge[CyNC(Me)NCy]2 (Cy = cyclohexyl) [19]
have a planar environment due to pp–dp and pp–pp con-
jugation. The consideration of the structure of 7 indi-
cates that steric factors could not affect the geometry
of the N(1) and N(2) atoms. The geometry change can
be caused by specific charge localization in the co-ordi-
nated fragment which makes impossible the conjugation
according to the canonical formula ‘‘B’’:
˚
The distance Ge(1)ꢀ ꢀ ꢀP(1) (2.563(1) A) is significantly
shorter than the sum of the van der Waals radii of these
˚
atoms (3.9 A [15]). Owing to such coordination the ger-
manium atom adopts pyramidal pseudo-sp3 configura-
tion. It is worth noting that the Ge(1)ꢀ ꢀ ꢀP(1) distance
˚
(2.563(1) A) in compound 7 is within the range of sim-
ilar distances in germanium (II) phosphinometanid,
˚
Ge[(Me2P)3C]2, (2.36–2.93 A [16]). The coordination
of one of the N(Ph)N(Ph)PPh2 groups leads to signifi-

3066
Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
of soft phosphine as supporting ligand or the utilization
of sterically hindering ligands [20]. In our investigation
we used the first approach. The behavior of phos-
phinohydrazide ligands bonded to late transition metal
seems to be intriguing from this point of view.
P
P
~
Ge
N
N
~
Ge
N
N
Lithium diphenylphosphino-1,2-diphenylhydrazide
(3a) easily reacts at room temperature with cobalt (II)
and nickel (II) halides in THF forming dark colored
solutions. The attempts to separate pure samples of Co
(II) and Ni (II) phosphinohydrazides, M[NAr–NAr–
PPh2]2 (Eq. (9)), were unsuccessful and lead to a mixture
of small-sized crystals of different nature. The prolonged
heating of the solutions yields, however, the individual
product. Poor soluble Ni and Co complexes 9, 10 (Eq.
(8)) are formed quantitatively in both reactions. These
compounds show high thermal stability, and have identi-
B
A
It is interesting that the 31P NMR spectrum of 7 at
ambient temperature shows only one resonance at 63.2
ppm, which can indicate the absence of coordination un-
der these conditions or the existence of
equilibrium.
a fast
2.6. Zn[N(Ar)–N(Ar)–PPh2]2 (8a, b)
cal IR spectra with strong peaks at 1300 and 1270 cmꢁ1
.
ArN
o
PPh
20 C
2
Anhydrous zinc chloride reacts with lithium phos-
phinohydrazides 2a and 2b in tetrahydrofurane to form
yellow solutions. After work up we succeeded to sepa-
rate a fine crystalline yellow precipitate of 8a from ether
solution.
M
NAr
+MCl
2Ar-N
2
THF
-2LiCl
N(Ar)Li
PPh
2
2
Ar
N
Ar
N
o
60 C
ð9Þ
ZnCl2 þ 2Ph2P–NðArÞ–NðArÞLi
M
Ph P
PPh
2
2
! Zn½NðArÞ–NðArÞ–PPh2ꢃ þ 2LiCl
ð8Þ
N
N
2
Ar ¼ Ph ð8aÞ; p-But–C6H4– ð8bÞ
Ar
Ar
9 M= Co, Ar= Ph
10 M= Ni, Ar= Ph
The appearance of two single resonances in the 31P NMR
spectrum of 8a at d = 63.10 and 63.16 ppm is indicative of
the existence of the P!Zn coordination in solution. In
the case of a bidentate coordination of two NNP moie-
ties, zinc should adopt a tetrahedral geometry and the
phosphorus atoms will be equivalent. It may be proposed
therefore that the coordination of only one NNP group
to the zinc atom takes place in solution. Compound 8b
was prepared as viscous oil. 31P NMR spectrum shows
resonances at d = 63.00 and 62.91 ppm. Our attempts
to crystallize the product from various solvents were
unsuccessful. Compounds 8a, 8b are moisture sensitive
and yield free ligands 2a and 2b after alkaline hydrolysis.
t
11 M= Co, Ar= -C H -Bu
6 4
Lithium diphenylphosphino-1,2-di(p-tert-butylphe-
nyl)hydrazide (6b) reacts with CoCl2 in the same way.
The final complex (11) is better soluble and can be
recrystallized from various solvents.
The crystals suitable for an X-ray study were pre-
pared from a toluene solution. The structure of cobalt
complex 11 is depicted in the Fig. 3. Selected bond dis-
tances and angles for 11 are given in Table 4. Each ami-
noiminophosphorane ligand is bonded to the cobalt(II)
center by a N,N0-chelating fashion, forming a {CoN4P2}
moiety. Both CoN2P-fragments are planar within 0.06
˚
A. The coordination of the Co atom is a significantly
2.7. The behavior of phosphinohydrazide ligands depend-
ing on transition metal nature and the environment
distorted tetrahedron with dihedral angles between two
average CoN2P planes of 82.7(2)ꢁ. The Co–N bond dis-
tances are similar with an average distance of 2.015(11)
2.7.1. Co, Ni
˚
A. The planar conformation of the PN2Co fragments
The metal–nitrogen bond in amido complexes (LnM–
NR2) of late transition metals is relatively weak in com-
parison with the other late-metal M–X bonds (halide,
alkyl, hydrido, etc.). This is in part due to the contrast
between the hard nitrogen-donor ligands and the soft
electron rich metals, that is considered to be energeti-
cally destabilizing. This effect is exacerbated by the gen-
eral lack of stabilizing p-donor interactions. Strategies
for the synthesis of amido complexes of the low-valent
late transition metals usually involve the incorporation
with the close values of the Co–N distances testify to
the delocalized structure of Ph2P(NAr)2 ligands without
a p-interaction with the metal atom:
Ph
Ph
Ph
Ph
Ph
Ph
P
P
P
_
Ar-N
__
N-Ar
Ar-N
N-Ar
_
_
N-Ar
_
Ar-N
_
_
_

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3067
Note, cobalt and nickel cyclophosphazane complexes
(9, 10) were isolated and characterized earlier as prod-
ucts of the reaction of lithium diphenylphosphinophe-
nylamide (Ph2P–NPh–Li) with metal halides (Eq. (10))
[21].
Ph
N
Ph
N
Ph P-N(Ph)Li
2
M
PPh
+
Ph P
(Ph P) MCl
2
2
3
2
2
LiCl
N
Ph
N
Ph
9 M= Co
10 M= Ni
ð10Þ
Ph
N
Ph
N
Ph
P
2
+ other
products
PPh
Ph P
2
M
M
+
2
N
N
P
Ph
Ph
Ph
2
In the course of these non-stoichiometric reactions a
cleavage and a formation of new P–N bonds occurred.
We explored also another approaches to 9. The heat-
ing of free ligand Ph2P–NPh–NPhH with cobalt(II)
silylamide cleanly affords fine crystalline 9:
Fig. 3. Molecular structure of [(ButC6H4N‚Ph2P–NC6H4But)2Co] Æ
(C7H8) (11). The H atoms and solvent molecule are omitted for
clarity.
Co½NðSiMe3Þ ꢃ þ 2Ph2P–NPh–NPhH
2 2
! Co½NPh–PPh2@NPhꢃ þ2ðMe3SiÞ NH
ð11Þ
Table 4
2
2
t
˚
9
Selected bond lengths (A) and angles (ꢁ) for [Bu C6H4N‚Ph2P–
NC6H4But]2Co (C7H8) (11)
The reaction of CoCl2 with lithium salts of aminoimino-
phosphorane 4 in THF gave the same final product 9.
Co(1)–N(1)
Co(1)–N(2)
Co(1)–N(3)
Co(1)–N(4)
Co(1)–P(1)
Co(1)–P(2)
P(1)–N(1)
P(1)–N(2)
P(2)–N(3)
P(2)–N(4)
2.025(4)
2.017(5)
1.999(4)
2.020(4)
2.6730(16)
2.6704(16)
1.602(5)
1.624(5)
1.603(5)
1.623(5)
CoCl2 þ 2Li½NPh–PPh2@NPhꢃ
! Co½NPh–PPh2@NPhꢃ þ2LiCl
ð12Þ
2
9
It is necessary to notice that the last reaction proceeds
slower than reaction (9), perhaps due to less nucleophil-
ity of the [PhN–PPh2‚NPh]ꢁ anion caused by the
charge delocalization in this fragment.
The reason of the rearrangement (Eq. (9)) is not com-
pletely clear since nickel and cobalt as a late transition
metals usually form strong coordination bonds to terti-
ary phosphines. Perhaps, the formation of the NPN-
moiety with tetracoordinate phosphorus combined with
the N,N0-amidinate-like bonding to nickel (cobalt) are
thermodynamically more favorable than the phosphorus
pp–dp back donation to nickel atom together with week
a single amido-bond N–Ni (N–Co).
The course of PNN-ligand transformation essentially
depends on metal oxidation state and metal environ-
ment. When nickel(I) bis(triphenilphosphine)–bis
(trimethylsilyl)amide (12) reacts with free phos-
phinohydrazine 2a we find a single isolated crystalline
product – bis(triphenylphosphino)azobenzene nickel(0)
complex (13). The structure of 13 was confirmed by
the X-ray analysis (Fig. 4)
N(1)–Co(1)–N(2)
N(1)–Co(1)–N(3)
N(1)–Co(1)–N(4)
N(2)–Co(1)–N(3)
N(2)–Co(1)–N(4)
N(3)–Co(1)–N(4)
N(1)–Co(1)–P(2)
N(2)–Co(1)–P(2)
N(3)–Co(1)–P(1)
N(4)–Co(1)–P(1)
P(1)–Co(1)–P(2)
N(1)–P(1)–N(2)
N(3)–P(2)–N(4)
C(13)–N(1)–P(1)
C(13)–N(1)–Co(1)
P(1)–N(1)–Co(1)
C(23)–N(2)–P(1)
C(23)–N(2)–Co(1)
P(1)–N(2)–Co(1)
C(45)–N(3)–P(2)
C(45)–N(3)–Co(1)
P(2)–N(3)–Co(1)
73.62(18)
126.96(19)
125.85(18)
124.75(18)
141.33(19)
73.59(18)
133.38(13)
151.56(13)
132.95(14)
152.31(13)
164.87(6)
97.3(2)
96.5(2)
130.0(4)
135.1(4)
94.2(2)
128.6(4)
137.9(3)
93.8(2)
128.7(4)
135.6(4)
95.1(2)

3068
Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
Table 5
Ph P
3
SiMe
SiMe
3
PhMe
˚
Selected bond lengths (A) and angles (ꢁ) for 13
Ni
N
+ Ph P-NPh-NPh-H
2
Ni(1)–N(1)
Ni(1)–P(1)
P(1)–C(13)
P(1)–C(7)
1.9450(15)
2.1985(5)
1.8269(17)
1.8312(17)
1.8424(17)
1.371(3)
Ph P
3
3
2a
12
ð13Þ
Ph
Ph P
3
P(1)–C(19)
N(1)–N(1a)
N(1)–C(1)
N
unidentified
products
Ni
13
+( Me Si) NH +
3
2
1.437(2)
N
Ph P
3
Ph
N(1)–Ni(1)–N(1a)
N(1a)–Ni(1)–P(1)
N(1)–Ni(1)–P(1)
P(1)–Ni(1)–P(1a)
N(1a)–N(1)–C(1)
N(1a)–N(1)–Ni(1)
C(1)–N(1)–Ni(1)
41.26(8)
144.65(4)
105.74(4)
109.00(3)
110.66(16)
69.37(4)
(50%)
The molecule 13 is an analogue of known bis(trit-
olylphosphino)azobenzene nickel(0) [22], so the struc-
tural parameters of the both molecules are very similar.
Selected bond distances and angles for 13 are shown in
Table 5. We could not isolate any other products of this
reaction. According to the 31P NMR spectrum of the
residue, a complex mixture of phosphorus-containing
products was formed.
101.21(10)
The same product was prepared by the reaction of iro-
n(II) bromide with the lithium salt of phosphinohydra-
zine (2a). Compound 14 is moderately moisture and
oxygen sensitive. An alkaline hydrolysis of 14 under
anaerobic conditions in a water–ether mixture gives pure
phosphinohydrazine 2a and ferrous hydroxide. All at-
tempts to obtain the crystals of 14 using various solvents
(including coordinated ones) were in vain. We suppose it
might be due to a simultaneous formation of several la-
bile conformers (or coordination oligomers) of this com-
pound. The IR spectrum of 14 differs significantly from
the spectra of aminoiminophosphoranides 9, 10 and
contains a set of the bands of low to moderate intensity
in the 1300–800 cmꢁ1 region and strong peaks at 740
2.7.2. Fe
The phosphinohydrazine ligands show quite different
behavior dependent on the oxidation state of iron. Fer-
rous bis(trimethylsilyl)amide slowly reacts with phos-
phinohydrazine 2a in toluene to form a thermally
stable dark green solution of 14. The solvent and hexa-
methyldisilazane were removed in vacuum yielding a
black-green powder of 14
Fe½NðSiMe3Þ ꢃ þ 2Ph2P–NPh–NPhH
! Fe½NPh–NPh–PPh2ꢃ þ2ðMe3SiÞ NH
2 2
and 690 cmꢁ1
.
In contrast to the iron(II) compound, iron(III) silyla-
ð14Þ
2
2
14
mide reacts with 2a to form aminnoiminophosphoranate
15
Fe½NðSiMe3Þ ꢃ þ 3Ph2P–NPh–NPhH
2 3
! Fe½NPh–PPh2@NPhꢃ þ3ðMe3SiÞ NH
ð15Þ
3
2
15
Iron(III) complex 15 was separated as air stable, poor
soluble, fine yellow crystals. The IR spectrum of 15 is
identical to the spectra, obtained for nickel and cobalt
aminoiminophosphoronates 9 and 10. The main feature
of these spectra is very strong absorptions at 1300 and
1270 cmꢁ1, assigned to the stretching vibrations of the
N–PV‚N moiety.
2.7.3. Cr, Mn
Chromium and manganese phosphinohydrazides
16a, 16b can be prepared by the reaction of anhydrous
CrCl3 or MnCl2 with lithium salt 6a in THF solution.
MCln þ nPh2P–NPh–NPhLiðEt2OÞ
6a
! M½NPh–NPh–PPh2ꢃn þnLiCl
ð16Þ
16;17
16 M ¼ Cr; n ¼ 3
17 M ¼ Mn; n ¼ 2
Fig. 4. Molecular structure of (Ph3P)2Ni(PhN‚NPh) (13). The H
atoms are omitted for clarity.

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3069
Chromium phosphinohydrazide (16) is a dark brown
3. Experimental
powder, stable in air. The toluene solutions of 16 are
not decomposed by aqueous acids (!) (AcOH, HCl),
but 16 reacts easily with a 25% aqueous ammonia solu-
tion to form chromium hydroxide and free ligand 2a.
Manganese (II) phosphinohydrazide, in contrast to 16,
is easily oxidized in air. An anaerobic treatment of 17
with a 25% aqueous ammonia solution yields manga-
nese hydroxide (II) and free ligand as well. Unfortu-
nately, manganese(II) phosphinohydrazide (17) cannot
be considered as an individual compound, since chlorine
content was found to be 3%.
3.1. General considerations
Solvents were purified following standard methods
[26]. Toluene and methylene chloride were thoroughly
dried and distilled over P2O5 prior to use. Ether and
THF were dried and distilled over Na/benzophenone.
Metal silylamides Fe[N(SiMe3)2]2 [27], Co[N-
(SiMe3)2]2 [27,28], (Ph3P)2NiN(SiMe3)2 [29], [CuN(Si-
Me3)2]n [30,31] were prepared according to known
methods. All manipulations were performed with rigor-
ous exclusion of oxygen and moisture, in vacuum or
under an argon atmosphere using standard Schlenk
techniques.
Hexamethyldisilazane liberated in the course of the
metal silylamides reactions was detected by gas chroma-
tography analyses with Tsvet-500 device, equipped with
stainless steel columns 0.4 cm · 200 cm, packed with 5%
SE-30 on Chromatone N-Super, with a thermoconduc-
tivity detector and with helium as carrier gas.
Spectrophotometric determination of transition met-
als (Mn, Cr, Fe, Co, Ni, Cu) in the prepared compounds
was provided by the methods described in [32].
Infrared spectra were recorded on a Perkin–Elmer
577 spectrometer from 4000 to 400 cmꢁ1 in nujol.
NMR spectra were recorded in CDCl3 or C6D6 solu-
tions using ‘‘Bruker DPX-200’’ device, with Me4Si as
internal standard.
2.7.4. Cu
Copper is known of its tendency to form more relia-
ble coordination bonds with phosphines as compared to
amines in the complexes containing ambidentate amino-
phosphine ligands.
The reaction of copper(I) silylamide with hydrazo-
phosphine Ph2P–NPh–NPhH leads to the formation
of orange crystalline adduct (Me3Si)2NCu(Ph2P–NPh–
NPhH)2 (18) which gives red insoluble copper diphenyl-
phosphide (19), azobenzene and initial ligand on heating
in toluene solution.
½CuNðSiMe3Þ ꢃ þ 2Ph2P–NPh–NPhH
2 n
20 ꢄC
! ðMe3SiÞ NCuðPh2P–NPh–NPhHÞ
ð17Þ
2
2
18
ꢄ
18 PhMe; 80 C
!
½Ph2PCuꢃn þPhN@NPh
3.2. X-ray structure determinations
19
þ Ph2P–NPh–NPhH þ ðMe3SiÞ NH
Compound 19 was prepared earlier by another way in
ð18Þ
2
A summary of crystal data collection and refinement
parameters for 2a, 7, 11 and 13 are given in Table 1. X-
ray diffraction data were collected on a Bruker SMART
APEX CCD (7, 11, 13) and a Bruker P4 diffractometer
the reaction of Ph2PSiMe3 with CuCl [23].
As a rule the reactions involving transition metal silyl-
amides require more acidic reagents than (Me3Si)2NH to
substitute silylamide function with another group. Phos-
phinohydrazines seem to be not much more acidic than
hexamethyldisilazane. However, the reactions of 2a with
copper, nickel and cobalt silylamides proceed quite rap-
idly. Apparently this is due to formation of a coordina-
tion metal–phosphorus bond on the first stage of the
reaction. This is confirmed by formation of compound
18.
Possessing two different coordination sites and rela-
tively week P–N and N–N bonds, phosphinohydraz-
ide-ligand shows a variable behavior depending on a
transition metal, its oxidation state and a ligand sur-
rounding. For example, it is known that the reaction
of bisphosphinohydrazine (MeO)2PN(Me)N(Me)P
(MeO)2 with tricobalt cluster PhCCo3(CO)9 produced
an unexpected compound with the phosphorus–phos-
phorus bond, [PhCCo3(CO)8]2[(MeO)2PP(OMe)2], sug-
gesting the formal loss of the ‘‘N(Me)N(Me)’’
fragment [24,25].
equipped with
a
CCD detector (2a) (Mo Ka
˚
(k = 0.71073 A)) at 223(2) (2a), 243(2) (7) and 100 (13)
K. X-ray diffraction experiment for 11 was carried out
at room temperature (293 K) because crystals shattered
at low temperature. Space groups of symmetry for 7, 11
and 13 were determined based on systematic absences.
All data sets were treated with SADABS absorption cor-
rections (Sheldrick, G., Bruker-AXS, 2001). The struc-
tures were solved using direct methods and difference
map techniques, and were refined by full-matrix least-
squares procedures on F2. All non-hydrogen atoms were
refined with anisotropic displacement parameters. The
H atoms in 2a were found on the F-map and refined
with isotropic thermal parameters. In the other struc-
tures the H atoms were treated as idealized contribu-
tions. Disordered toluene molecules in 11 was treated
by SQUEEZE [34]; corrections of the X-ray data by
SQUEEZE (495 electron/cell) was slightly larger than
the required value (400 electron/cell). All software
and sources of scattering factors are contained in the

3070
Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
SHELXTL (5.10) program package (G. Sheldrick, Bruker
XRD, Madison, WI).
(the same those found for compound 4). Triphenylphos-
phine, however, was not found by HPLC analysis.
3.3.3. Ph2P–NC6H4But–NHC6H4But (2b)
3.3. Synthesis
A solution of 0.96 M n-buthyllithium in hexane (5.1
ml, 4.9 mmol) was added to a stirred solution of 1b
(1.46 g, 4.9 mmol) in 15 ml of toluene at room temper-
ature. After the mixture was kept for 0.5 h, a solution of
Ph2PCl (1.08 g, 4.9 mmol) in 5 ml of toluene was added.
The mixture was stirred for ca. 1 h when washed with
water to remove LiCl. The resulting solution was dried
over Na2SO4. Toluene was removed in vacuum and 15
ml of abs. ethanol was added. A crystallization over-
night at 0 ꢁC yields large colorless crystals of 2b (1.23
g, 52%). Anal. Calc. for C32H37PN2: C, 79.97; H, 7.76;
P, 6.44. Found: C, 79.63; H, 7.80; P, 6.38%. 31P {1H}
NMR (CDCl3): d 62.9 (s). 1H NMR, d 1.17 (9H, t-
BuC6H4NPPh2), 1.29 (9H, t-BuC6H4NH); 6.01 (1H,
NH); 6.28 and 6.87 (DD, J3 = 8.5 Hz, 4H, t-
BuC6H4NH); 7.1–7.7 (m, 14H, (C6H5)2P and t-
BuC6H4NP). IR (Nujol) m(cmꢁ1): 3350 (m), 3320 (w),
1610 (s), 1510 (s); 1380 (m), 1370 (m) (t-Bu), 1180 (m),
1120 (m), 1100 (w), 1000 (w), 920 (m), 830 (s), 750
(m), 730 (m), 700 (s), 560 (m), 530 (w), 500 (m).
3.3.1. [p-tBu–C6H4–NH]2 (1b)
Zinc powder (14 g) was added stepwise to a boiling
mixture of p-tert-butylnitrobenzene (6.3 g) in 35 ml of
isopropyl alcohol and 10 g of NaOH in 30 ml of water.
Hot colorless organic lawyer was decanted under argon
atmosphere. Colorless crystals of 1b were precipitated
by cooling the solution to room temperature. The crys-
tals were washed with cold hexane and dried in vacuum.
Yield: 2.76 g (53%). Anal. Calc. for C20H28N2: C, 81.03;
1
H, 9.52. Found: C, 80.63; H, 9.44%. H NMR, d 1.29
(18H, t-Bu); 5.53 (2H, NH); 7.25 and 6.82 (DD, 8H,
JH3 ;H ¼ 8:0 Hz, –C6H4–). IR (Nujol), m (cmꢁ1): 3320
(m), 1600 (s), 1520 (m),1510 (m); 1380, 1370 (m) (D, t-
Bu); 1280 (w), 1260 (vw), 1250 (m) (t-Bu), 1170 (m),
1100 (m), 820 (s), 720 (m), 620 (w), 550 (m), 530 (m).
3.3.2. Ph2P–NPh–NHPh (2a)
A hexane solution of n-BuLi (1.0 M, 8.2 ml) was
added to a stirred solution of 1,2-diphenylhydrazine
(1a) (1.51g, 8.2 mmol) in 15 ml of toluene at 0 ꢁC. After
stirring for 10 min Ph2PCl (1.81 g, 8.2 mmol) in 10 ml of
toluene was added dropwise. A colorless solution turned
orange. The reaction mixture was kept at room temper-
ature for 30 min and washed with water to remove LiCl.
The resulting solution was dried over Na2SO4, the major
part of the solvent was removed in vacuum and 15 ml of
abs. ethanol was added. A slow crystallization at 20 ꢁC
was completed in about 5 h to leave colorless crystals of
2a. Yield: 1.60 g (53%). Anal. Calc. for C24H21PN2: C,
78.24; H, 5.75; P, 8.41. Found: C, 78.12; H, 5.43; P,
Thermal destruction of 2b was carried out by analogy
with 2a. Only tentative suggestions may be done for
some products, registrated by 31P NMR sectroscopy:
(d, ppm) 29.3 (23%, ꢂt-BuC6H4–NH–PPh2), 27.9 (9%),
t
12.4 (5%), 11.05 (19%), ꢁ4.43 (38%, ꢂ BuC6H4–NH–
PPh2‚NC6H4But).
3.3.4. [PhNH–PPh2‚NPh] Æ 2HCl (3)
A mixture of hydrazobenzene (1.85 g, 10.0 mmol)
and Ph2PCl (2.22 g, 10.0 mmol) in 20 ml of methylene
chloride has been left for two days at 20 ꢁC. The plenti-
ful white crystalline residue has been filtered and dried
up in vacuum. Yield of (3): 4.32 g (ꢂ 98%). Anal. Calc.
for C24H23PN2Cl2: C, 65.32; H, 5.25; Cl, 16.07; P, 7.02.
Found: C, 65.41; H, 5.30; Cl, 16.21; P, 6.93%. 31P {1H}
NMR (CDCl3): d 30.37 ppm. IR (Nujol) m(cmꢁ1): 1600
(s), 1500 (s), 1440 (m), 1420 (w), 1280 (m), 1210 (m),
1120 (s), 1030 (w), 1010 (w), 990 (m), 940 (m), 760 (s),
730 (s), 690 (s), 590 (w), 520 (w), 500 (w), 450 (w).
8.73%. 31P NMR (CDCl3), d (ppm): 63.62, H NMR d
1
(ppm): 5.97 (s, 1H, NH), 6.3–7.4 (m, 20H). IR (Nujol),
m, cmꢁ1: 3330 (m), (NH), 1580 (s), 1430 (w), 1300 (w),
1270 (m), 1225 (m), 1190 (m), 1120 (m), 1100 (m),
1020 (m), 1000 (w), 950 (m), 910 (m), 880 (w), 740 (s),
730 (sh), 690 (s), 530 (w), 500 (vw).
Thermal destruction of 2a. A sample of 2a (0.15 g, 0.4
mmol) was placed into a long glass tube. The thermoly-
sis was carried out in vacuum (0.1 mm Hg) at slow heat-
ing (2 ꢁC/min) up to 150 ꢁC and maintaining for 30 min
at this temperature. Destruction of 2a begins at 140 ꢁC.
Azobenzene sublimes at the top of the ampoule. It was
isolated (0.036 g, ꢂ0.2 mmol) and identified by HPLC
(Silasorb C16T, 64 · 2; CH3OH:H2O = 75:25; F = 100
mkl/min, k = 210 nm, retention time 800500). Brown solid
residue was analysed by 31P NMR spectroscopy. The
main signals were (d, ppm): 29.4 (18%, tentatively
PhNH–PPh2 [7,33]), 19.9 (8%), 11.1 (8%), ꢁ4.08 (37%,
PhNH–PPh2‚NPh (4)), ꢁ13.7 (8%, tentatively Ph2P–
PPh2). Note, that Ph3P shows resonance at d = ꢁ4, 08
3.3.5. PhNH–PPh2‚NPh (4)
A solution of 10% ammonia (10 ml) is added to a sus-
pension of 3 (4.32 g) in diethyl ether (30 ml). Dissolution
of 3 and partial precipitation of a new crystalline prod-
uct was observed. The suspension was washed with dis-
tilled water. Ether was removed in vacuum. The
crystalline residue was pumped in vacuum. Crystalliza-
tion from warm toluene gave 3.42 g (95%) of 4. Anal.
Calc. for C24H21PN2: C, 78.26; H 6.79; P 8.42. Found:
C 78.34; H 6.72; P 8.38%. 31P {1H} NMR (CDCl3): d-
4.08 ppm. IR (Nujol) m(cmꢁ1): 3060 (w), 1600 (s), 1490
(s), 1410 (w), 1300 (vs), 1230 (m), 1170 (w), 1120 (m),

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3071
1060 (m), 1020 (w), 1000 (w), 930 (s), 760 (s), 720 (m),
700 (s), 580 (m), 525 (s). HPLC: CH3OH/H2O = 90/10;
Diasorb C16T, 7l; colomn 64 · 2 mm, F = 100 ll/min;
k = 210 nm. Retention time 305000 and 402000.
(m), 1020 (w), 910 (m), 850 (m), 730 (vs), 700 (vs), 500
(w), 480 (w), 450 (w). T dec 135 ꢁC. 31P{1H} NMR
(C6D6): d = 63.10 and 63.16 ppm.
The alkaline hydrolysis of 8a was carried out in
water/ether mixture to form free base 2a which were
characterized by IR-spectroscopy and elemental
analysis.
3.3.6. Ph2P–NPh-NPh–Li (5a) and Ph2P–NPh–NPh–
Li(Et2O) (6a)
A hexane solution of n-BuLi (1.0 M, 4.2 ml) was
added to a stirred solution of 2a (1.55 g; 4.2 mmol) in
15 ml of toluene. The solvent was removed in vacuo.
The oily residue (5a) shows 31P NMR resonance
3.3.10. Zn(NAr–NAr–PPh2)2, Ar = p-But–C6H4– (8b)
Compound 8b was prepared by analogy with 8a. Yel-
low viscous oil. Yield: 94%. Anal. Calc. for
C64H72P2N4Zn: C, 75.02; H, 7.08; Zn, 6.38. Found: C,
75.10; H, 6.95; Zn, 6.23; Cl (remaining), 0.4%. IR (Nu-
jol) m(cmꢁ1): 1320 (w), 1280 (w), 1240 (m), 1110 (m),
1000 (m), 945 (m), 830 (m), 730 (s), 690 (s), 550 (m),
500 (m). T dec 135 ꢁC. 31P{1H} NMR (C6D6):
d = 63.0 and 62.91 ppm.
7
(C6D6) d 55.0 ppm and Li NMR d 2.90 ppm.
To a prepared toluene solution of 5a (15 ml), 1 ml of
Et2O was added. The mixture was maintained overnight
at 0 ꢁC. The solvent was decanted; colorless crystals of
6a were washed with toluene and dried in vacuo. Yield:
1.8 g (96%). Anal. Calc. for C28H30PN2LiO: C, 74.99; H,
6.74; Li, 1.55. Found: C, 74.78; H, 6.79; Li, 1.50%.
3.3.11. Co(NPh–PPh2‚NPh)2 (9)
3.3.7. Ph2P–N(C6H4But)–N(C6H4But)Li(Et2O) (6b)
The procedure is similar to 5a. Colorless crystals.
Yield: 0.72 g (68%). Anal. Calc. for C36H46PN2LiO: C,
77.12; H, 8.27; Li, 1.24. Found: C, 77.06; H, 8.32; Li,
1.21%.
(A) A solution of CoCl2 (0.13 g, 1.0 mmol) in 20 ml of
THF was added to a stirred solution of 5a (0.75 g; 2.0
mmol) in 10 ml of the same solvent. The mixture imme-
diately turned dark-brown. The color of the solution
slowly turned violet-green at heating. Maintaining of
the mixture at 80 ꢁC during 12 h led to a fine crystalline
pink precipitate of 9 (the precipitation of LiCl was not
observed). The solvent was decanted; the crystals were
washed with THF and dried in vacuum. Yield: 0.75 g
(95%). Anal. Calc. for C48H40P2N4Co: C, 72.63; H,
5.08; Co, 7.42. Found: C, 72.80; H, 5.11; Co, 7.38; Cl
(remaining), 0.2%. IR (Nujol) m(cmꢁ1): 1590 (s), 1300
(vs), 1270 (s), 1170 (m), 1100 (s), 1030 (m), 1000 (m),
980 (m), 800 (s), 760 (m), 720 (m), 700 (m), 640 (m),
500 (s).
(B) A toluene solution containing 0.38 g of Co[N(-
SiMe3)2]2 (1.0 mmol), 0.74 g (2.0 mmol) of phos-
phinohydrazine 2a was heating at 80 ꢁC for 6 h. The
formed pink crystalline residue was washed with THF
and dried in vacuum. Yield: 0.77 g (97%).
(C) A hexane solution of n-BuLi (1.0 M, 2.0 ml) was
added to a stirred solution of PhNH–PPh2‚NPh (4)
(0.75 g, 2.0 mmol) in 15 ml of toluene. The solvent
was removed in vacuum and changed for THF. A solu-
tion of CoCl2 (0.13 g; 1.0 mmol) in 20 ml of THF was
added. The mixture turned dark-brown. Maintaining
of the mixture at 80 ꢁC during 12 h led to a fine crystal-
line pink precipitate of 9 (The precipitation of LiCl was
not observed). The solvent was decanted; the crystals
were washed with THF and dried in vacuum. Yield:
0.71 g (90%).
3.3.8. Ge(NPh–NPh–PPh2)2 (7)
A solutions of GeCl2(C4H8O2) (0.46 g, 2.0 mmol) in
15 ml of THF, and 5a (1.79 g, 4.0 mmol) in 15 ml
THF were mixed at ꢁ50 ꢁC. Colorless solution immedi-
ately turned orange-red. After stirring for 1 h at 0 ꢁC the
solvent was removed in vacuum and changed for tolu-
ene. The precipitate (LiCl) was filtered off, toluene was
removed in vacuum and changed for Et2O. Bright-yel-
low fine-crystalline precipitate was formed for 2 h at
20 ꢁC. Mother liquor was decanted; the precipitate
was recrystallized from warm Et2O and dried in vac-
uum. Yield: 1.22
g
(76%). Anal. Calc. for
C48H40P2N4Ge: C, 71.40; H, 4.99; P, 7.67; Ge, 8.99.
Found: C, 71.70; H, 5.00; P, 7.81; Ge, 9.15%. IR (Nujol)
m(cmꢁ1): 1580 (m), 1250 (w), 1230 (m), 1080 (m), 1020
(m), 870 (m), 840 (w), 730 (s), 700 (s), 500 (m).
31P{1H} NMR (CDCl3): d 63.2 (s). T dec 135 ꢁC.
3.3.9. Zn(NPh–NPh–PPh2)2 (8a)
A solutions of 5a (3.74 g in 20 ml of THF (10.0
mmol)) and anhydrous ZnCl2 (0.68 g in 10 ml of THF
(5.0 mmol)) were mixed at 0 ꢁC. Colorless solution rap-
idly turned bright yellow. After stirring for 30 min at 20
ꢁC the solvent was removed in vacuum and changed for
toluene. The precipitate (LiCl) was filtered off. The clean
solution was concentrated to 15 ml and maintained
overnight at 20 ꢁC to give deep yellow crystals. Yield:
3.80 g (95%). Anal. Calc. for C48H40P2N4Zn: C, 72.05;
H, 5.04; P, 7.74; Zn, 8.17. Found: C, 71.94, H, 5.12, P,
7.70, Zn, 8.20; Cl (remaining), 0.5%. IR (Nujol)
m(cmꢁ1): 1590 (s), 1300 (w), 1230 (m), 1150 (w), 1080
3.3.12. Ni(NPh–PPh2‚NPh)2 (10)
The procedure is similar to the synthesis of 9a by the
method A. Ruby-brown fine crystals. Yield: 95%. Anal.
Calc. for C48H40P2N4Ni: C, 72.65; H, 5.08; Ni, 7.40.
Found: C, 72.73; H, 5.13; Ni, 7.31; Cl (remaining),

3072
Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
0.1%. IR (Nujol) m(cmꢁ1): 1580 (s), 1290 (vs), 1260 (s),
1130 (w), 1100 (m), 1020 (w), 990 (w), 970 (w), 780
(m), 730 (m), 700 (w), 680 (m), 500 (m).
3.3.16. Fe(NPh–PPh2‚NPh)3 (15)
A mixture of Fe[N(SiMe3)2]3 (0.54 g, 1 mmol) and 2a
(1.10 g, 3 mmol) in toluene (20 ml) was maintained at 80
ꢁC for 12 h. Yellow fine crystalline precipitate of 15 was
filtered off, washed with toluene and dried in vacuum.
Yield 0.94 g (81%). Anal. Calc. for C72H60P3N6Fe: C,
74,67; H, 5.22; Fe, 4.82. Found: C, 74.61; H, 5.18; Fe,
4,78%. IR (Nujol) m(cmꢁ1): 1590 (s), 1300 (vs), 1270
(vs), 1170 (w), 1110 (m), 1130 (m), 1000 (m), 970 (m),
930 (w), 830 (w), 780 (m), 750 (m), 720 (w), 690 (m),
640 (m), 510 (s).
3.3.13. Co[N(C6H4But)–PPh2‚N–C6H4But]2 (11)
CoBr2 (0.22 g; 1.0 mmol) in 10 ml of THF was added
to a stirred solution of Ph2P–NC6H4But–NLiC6H4But
(1.12 g; 2.0 mmol) in 20 ml of the same solvent. The
starting green solution rapidly turned brown. The mix-
ture was heated at 70 ꢁC for 6 h. THF was removed
and changed for toluene. LiBr was filtered off. The clean
solution was concentrated to 10 ml and maintained
overnight at 0 ꢁC to give large pink-violet crystals.
Yield: 0.88 g (86%). Anal. Calc. for C64H72P2N4Co: C,
75.50; H, 7.13; Co, 5.79. Found: C, 75.56; H, 7.08; Co,
7.73%; IR (Nujol) m(cmꢁ1): 1600 (s), 1510 (s) (t-Bu),
1300 (vs), 1270 (s), 1180 (m), 1110 (s), 1370 (w), 1380
(w), 1000 (s), 1010 (w), 1000 (s), 830 (m), 800 (s), 750
(w), 730 (m), 710 (w), 700 (m), 640 (w), 590 (m), 550
(w), 520 (s).
3.3.17. [Ph2P–NPh–NPh]3Cr (16)
A solution of Ph2P–NPh–NLiPh (5a) (1.12 g, 3
mmol) in 20 ml of THF was added to a suspension of
CrCl3 (0.16 g, 1 mmol). Dissolution of CrCl3 was ob-
served and color of the mixture got dark brown rapidly.
The mixture was heated for 2 h at 50 ꢁC. The solvent
was removed in vacuum and changed for toluene. LiCl
was filtered off. Toluene was removed in vacuum to
leave black-brown powder of 16. Yield: 1.08 g (94%).
Anal. Calc. for C72H60P3N6Cr: C, 74.99; H, 5.24; Cr,
4.42. Found: C, 74.86; H, 5.30; Cr, 4.37%. IR (Nujol)
m(cmꢁ1): 1590 (s), 1260 (m), 1110 (m), 1120 (w), 980
(w), 810 (w), 740 (vs), 690 (vs), 510 (m), 460 (w).
Hydrolisis of 16. An toluene solution of 16 was trea-
ted with 25% NH4OH for 30 min. Chromium hydroxide
was filtered off, organic layer was separated, the solvent
was removed in vacuum and changed for ethanol. Col-
orless crystals of 2a were characterized by 31P, 1H
NMR and IR spectroscopy.
3.3.14. Reaction of (Me3Si)2NNi(PPh3)2 (12) with
Ph2P–NPh–NHPh (2a).
A mixture of 12 (0.74 g, 1 mmol) and 2a (0.37 g, 1
mmol) in toluene (20 ml) was maintained at room tem-
perature for 24 h. Brown-red crystals were separated
from mother liquor, washed with cold toluene and dried
in vacuum. Yield: 0.38 g (50%). Anal. Calc. for
C48H40P2N2Ni[(Ph3P)2Ni(PhN‚NPh)] (13): C, 75.31;
H, 5.27; Ni, 7.67. Found: C, 75.26; H-5.35; Ni 7.60%.
Crystals were investigated by X-ray analysis.
3.3.18. [Ph2P–NPh–NPh]2Mn (17) (attempt of the
synthesis)
3.3.15. [Ph2P–NPh-NPh]2Fe (14)
The synthesis of 17 from anhydrous MnCl2 and 5a is
analogous to 16. Dark-yellow powder from toluene.
Yield 0.73 g (93%). Anal. Calc. for C48H40P2N4Mn: C,
73.00; H, 5.11; Mn, 6.96. Found: C, 71.07; H, 5.23;
Mn, 7.84; Cl (remaining) 3.1%. IR (Nujol) m(cmꢁ1):
1600 (m), 1270 (w), 1230 (m) 1130 (m), 1100 (w), 1030
(m), 1000 (w), 920 (m), 740 (vs), 700 (vs), 570 (w).
Hydrolysis of 17. A toluene solution of 17 was treated
with an excess of 25% NH4OH under argon atmosphere
for 30 min. Manganese hydroxide was filtered off, or-
ganic layer was separated, the solvent was removed in
vacuum and change for ethanol. Colorless crystals of
2a were characterized by 31P, 1H NMR and IR
spectroscopy.
(A) A solution of lithium phosphinohydrazaide (5a)
(0.75 g, 2.0 mmol) in 10 ml of THF was added to a sus-
pension of FeBr2 (0.43 g, 1.0 mmol) in 10 ml of the same
solvent. The mixture was heated at 50 ꢁC for 12 h. The
solvent was change for hexane, LiBr was filtered off.
Hexane was removed in vacuum to leave black-green
powder of 14. Yield: 0.76 g (96%). Anal. Calc. for
C48H40P2N4Fe: C, 72.92; H, 5.10; Fe, 7.06. Found: C,
72.80; H, 5.20; Fe, 7.14%. IR (Nujol) m(cmꢁ1): 1570
(m), 1240 (m), 1160 (m), 1060 (w), 1020 (w), 920 (m),
830 (m) 765 (w), 720 (s), 680 (s).
Hydrolisis of 14. An ether solution of 14 was treated
with 10% NaOH. Ferrous hydroxide was filtered off,
ether layer was separated, ether was removed in vacuum
and change for ethanol. Colorless crystals of 2a were
3.3.19. (Me3Si)2NCu(Ph2P–NPh–NPhH)2 (18)
1
characterized by 31P, H NMR and IR spectroscopy.
A solution of (Me3Si)2NCu (0,22 g, 1 mmol) in 10 ml
of toluene was added to a solution of phosphinohydra-
zine 2a (0.74 g, 2 mmol) in the same solvent (10 ml). The
colorless solution turned yellow-orange. The mixture
was allowed to stay for 4 h before precipitation of the
product 18. Orange needle crystals were filtered, washed
(B) A mixture of Fe[N(SiMe3)2]2 (0.38 g, 1 mmol) and
2a (0.73 g, 2 mmol) in toluene (15 ml) was maintained at
50 ꢁC for 12 h. The solvent and hexamethyldisilazane
were removed in vacuum, to form black-green powder
of 14. Yield: 0.79 g (ꢂ100%).

Y.V. Fedotova et al. / Journal of Organometallic Chemistry 689 (2004) 3060–3074
3073
with toluene and dried in vacuum. Yield: 0.75 g (81%).
5. Supplymentary material
Anal. Calc. for C54H60P2N5Si2Cu: C, 67.51; H, 6.30;
Cu, 6.61. Found: C, 67.55; H, 6.34; Cu, 6.68%. IR (Nu-
jol) m(cmꢁ1): 3320 (w), 1590 (s), 1310 (w), 1270 (m), 1235
(m), 1170 (w), 1090 (m), 1030 (w), 980 (w), 950 (w), 870
(w), 740 (vs), 700 (vs), 500 (m). 31P{1H} NMR (C6D6), d
(ppm) 59.61; 1H NMR 7.8–7.0 (m, 40 H, Ph), 0.11 (s, 18
H, SiMe), 5.30 (s, 2H, NH).
The CIF are available from the Cambridge Crystallo-
graphic Data Center under the depositary number
CCDC 233897 (2a), 233900 (7), 233898 (11), 233899
(13).
Thermolysis of 18. A solution of 18 (0.96 g, 1 mmol)
in toluene (20 ml) was heated at 80 ꢁC for 2 h. Red
precipitate of {Ph2PCu}n was filtered off, washed with
toluene and dried in vacuum. Yield: 0.23 g (93%).
Anal. Calc. for C12H10PCu: C, 57.95; H, 4.05; Cu,
25.55. Found: C, 57.89; H, 4.10; Cu, 25.48%. IR (Nu-
jol) m(cmꢁ1): 1580 (w), 730 (m), 690 (m), 550 (m), 500
(m).
Acknowledgment
We are grateful to the Russian Foundation for Basic
Research (Grant 03-03-32051; Scientific Schools-
1649.2003.3, -1652.2003.3, -123.2003.01) for financial
support of this work.
The filtrate was analysed further. Toluene was re-
moved in vacuum; the residue was extracted with hex-
ane. The extract contained azobenzene according to
the HPLC analysis: Separon SGX, 5 l, 64 · 2; F = 200
ll/min, k = 220 nm; hexane/THF = 200/1; retention time
103500. Other conditions: Silasorb C16T, 64 · 2; CH3OH:
H2O = 75:25; F = 100 mkl/min, k = 210 nm, retention
time 800500).
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4. Conclusions
The present research has shown that the stability of
the metal complexes containing r-bonded phos-
phinohydrazide ligand {–NPh–NPh–PPh2} is strongly
dependent on the nature of the metal, its oxidation
state and ligand environment. Early and middle tran-
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centres. Compound of Ni(I), (Ph3P)2NiN(SiMe3)2, re-
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affords diphenylphosphide {Ph2PCu}n and azobenzene.
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