Rhenium(V) and technetium(V) complexes with phosphoraneimine and phosphoraneiminato ligands

Article abstract of DOI:10.1021/ic048210q

Air-stable rhenium(V) nitrido complexes are formed when [ReOCl ₃(PPh₃)₂], [NBu₄][ReOCl ₄], or [NBu₄][ReNCl₄] are treated with an excess of silylated phosphoraneiminates of the composition Me ₃SiNPPh₃ or Ph₂P(NSiMe₃)CH ₂PPh₂ in CH₂Cl₂. Complexes of the compositions [ReNCl(Ph₂PCH₂PPh₂NH) ₂]Cl (1), [ReN(OSiMe₃)(Ph₂PCH ₂PPh₂NH)₂]Cl (2) or [ReNCl₂(PPh ₃)₂] (3) were isolated and structurally characterized. The latter compound was also produced during a reaction of the rhenium(III) precursor [ReCl₃(PPh₃)₂(CH₃CN) and Me₃SiNPPh₃. Nitrogen transfer from the phosphorus to the rhenium atoms and the formation of nitrido ligands were observed in all examples. All products of reactions with an excess of the potentially chelating phosphoraneiminate Me₃SiNP(Ph₂)CH₂PPh ₂ contain neutral Ph₂PCH₂PPh₂NH ligands. The required protons are supplied by a metal-induced decomposition of the solvent dichloromethane. The Re-N(imine) bond lengths (2.055-2.110 A) indicate single bonds, whereas the N-P bond with lengths between 1.596 A and 1.611 A reflect considerable double bond character. An oxorhenium(V) phosphoraneiminato complex, the dimeric compound [ReOCl₂(μ-N- Ph₂PCH₂PPh₂N)]₂ (4), is formed during the reaction of [NBu₄][ReOCl₄] with an equivalent amount of Ph₂P(NSiMe₃)CH₂PPh₂ in dry acetonitrile. The blue neutral complex with two bridging phosphoraneiminato units is stable as a solid and in dry solvents. It decomposes in solution, when traces of water are present. The rhenium-nitrogen distances of 2.028(3) and 2.082(3) A are in the typical range of bridging phosphoraneiminates and an almost symmetric bonding mode. Technetium complexes with phosphoraneimine ligands were isolated from reactions of [NBu₄][TcOCl₄] with Me₃SiNPPh₃, and [NBu₄][TcNCl₄] with Me₃SiNP(Ph₂)CH₂PPh₂. Nitrogen transfer and the formation of a five-coordinate nitrido species, [TcNCl ₂(HNPPh₃)₂] (5), was observed in the case of the oxo precursor, whereas reduction of the technetium(VI) starting material and the formation of the neutral technetium(V) complex [TcNCl₂(Ph ₂PCH₂PPh₂NH)] (6) or [TcNCl(Ph ₂PCH₂PPh₂NH)₂]Cl (7) was observed in the latter case. Both technetium complexes are air stable and X-ray structure determinations show bonding modes of the phosphoraneimines similar to those in the rhenium complexes.

Full text of DOI:10.1021/ic048210q

Inorg. Chem. 2005, 44, 3172−3180
Rhenium(V) and Technetium(V) Complexes with Phosphoraneimine and
Phosphoraneiminato Ligands
Maren Hecht, Sonia Saucedo Anaya, Adelheid Hagenbach, and Ulrich Abram*
Freie UniVersit a¨ t Berlin, Institute of Chemistry, Fabeckstrasse 34-36, D-14195 Berlin, Germany
Received December 17, 2004
Air-stable rhenium(V) nitrido complexes are formed when [ReOCl
treated with an excess of silylated phosphoraneiminates of the composition Me
in CH Cl . Complexes of the compositions [ReNCl(Ph PCH PPh NH) ]Cl (1), [ReN(OSiMe
2) or [ReNCl (PPh
during a reaction of the rhenium(III) precursor [ReCl
phosphorus to the rhenium atoms and the formation of nitrido ligands were observed in all examples. All products
of reactions with an excess of the potentially chelating phosphoraneiminate Me SiNP(Ph )CH PPh contain neutral
Ph PCH PPh NH ligands. The required protons are supplied by a metal-induced decomposition of the solvent
dichloromethane. The Re N(imine) bond lengths (2.055 2.110 Å) indicate single bonds, whereas the N P bond
with lengths between 1.596 Å and 1.611 Å reflect considerable double bond character. An oxorhenium(V)
phosphoraneiminato complex, the dimeric compound [ReOCl -N-Ph PCH PPh N)] (4), is formed during the reaction
of [NBu ][ReOCl ] with an equivalent amount of Ph P(NSiMe )CH PPh in dry acetonitrile. The blue neutral complex
with two bridging phosphoraneiminato units is stable as a solid and in dry solvents. It decomposes in solution,
when traces of water are present. The rhenium nitrogen distances of 2.028(3) and 2.082(3) Å are in the typical
range of bridging phosphoraneiminates and an almost symmetric bonding mode. Technetium complexes with
phosphoraneimine ligands were isolated from reactions of [NBu ][TcOCl ] with Me SiNPPh , and [NBu ][TcNCl
with Me SiNP(Ph )CH PPh . Nitrogen transfer and the formation of a five-coordinate nitrido species, [TcNCl (HNPPh
5), was observed in the case of the oxo precursor, whereas reduction of the technetium(VI) starting material and
the formation of the neutral technetium(V) complex [TcNCl (Ph PCH PPh NH)] (6) or [TcNCl(Ph PCH PPh NH) ]Cl
7) was observed in the latter case. Both technetium complexes are air stable and X-ray structure determinations
show bonding modes of the phosphoraneimines similar to those in the rhenium complexes.
3
(PPh
3
)
2
], [NBu
4
][ReOCl
or Ph
)(Ph
4
], or [NBu
P(NSiMe
PCH PPh
4
][ReNCl
)CH
NH)
4
] are
3
SiNPPh
3
2
3
2
PPh
2
2
2
2
2
2
2
3
2
2
2
2
]Cl
(
2
3
)
2
] (3) were isolated and structurally characterized. The latter compound was also produced
(PPh (CH CN)] and Me SiNPPh . Nitrogen transfer from the
3
3
)
2
3
3
3
3
2
2
2
2
2
2
−
−
−
2
(µ
2
2
2
2
4
4
2
3
2
2
−
4
4
3
3
4
4
]
3
2
2
2
2
3 2
) ]
(
2
2
2
2
2
2
2
2
(
Introduction
high stability of the formed trimethylchlorosilane or hexa-
methyldisiloxane. Depending on the oxidation state of the
transition metal, the phosphoraneiminato ligands coordinate
Phosphoraneimine and phosphoraneiminato complexes are
known for a large number of main group and transition
2
linear, bent, or as bridging ligands. Electron-rich metal ions
metals.1 Since discrete R
-3
PN anions are hitherto unknown
-
3
prefer the formation of µ-N-bridged dimers or multinuclear
aggregates of heterocubane (four metal atoms) or partially
face-centered octahedral (six metal atoms) structures both
and even alkali metal derivatives are built of multinuclear
molecular aggregates, frequently trimethylsilylated phos-
phoraneimines are used for the synthesis of the transition
metal complexes. The driving force of the reactions is the
4
3
containing µ -bonded phosphoraneiminato ligands. Com-
(
4) (a) Batsanov, A. S.; Davidson, M. G.; Howard, J. A. K.; Lamb, S.;
*
To whom correspondence should be addressed. Tel. (#49) 30 83854002,
Lustig, C.; Price, R. D. J. Chem. Soc., Chem. Commun. 1997, 1211.
(b) Anfang, S.; Seybert, G.; Harms, K.; Geiseler, G.; Massa, W.;
Dehnicke, K. Z. Anorg. Allg. Chem. 1998, 624, 1187. (c) Chitsaz, S.;
Neum u¨ ller, B.; Dehnicke, K. Z. Anorg. Allg. Chem. 1999, 625, 9.
(d) Chitsaz, S.; Neum u¨ ller, B.; Dehnicke, K. Z. Anorg. Allg. Chem.
2003, 629, 592.
FAX (#49) 30 83852676, e-mail: abram@chemie.fu-berlin.de.
1) Dehnicke, K.; Weller, F. Coord. Chem. ReV. 1997, 158, 103.
2) Dehnicke, K.; Krieger, M.; Massa, W. Coord. Chem. ReV. 1999, 182,
(
(
19 and references therein.
(
3) Dehnicke, K. Z. Anorg. Allg. Chem. 2003, 629, 729.
3172 Inorganic Chemistry, Vol. 44, No. 9, 2005
10.1021/ic048210q CCC: $30.25
© 2005 American Chemical Society
Published on Web 03/31/2005

Re(V) and Tc(V) Complexes with Phosphoraneimines
plexes with linear or slightly bent nitrogen-bridges between
the metal and the phosphorus atoms are formed by metals
in high formal oxidation states, as has been demonstrated
for Os(VIII) or Re(VII) compounds.
Stable donor-acceptor complexes with trimethylsilylated
Chart 1. Phosphoraneiminates Used
5
6
phosphoraneimines or ligands of the type R
established for a series of metal(II) halides and group IV
and group V metals.2,8 Only a few structurally characterized
3
2
PdNH are well
,7
proceed on this concentration level. The same holds true for
6
e,9
the claimed synthesis of the neutral O
NH )TcO and Me SiNPPh in dry toluene. A series of
oxo complexes with phosphoraneiminates have been de-
scribed as products of the reaction between Re and
3 3
TcdNPPh from
examples are known for metals of the groups VI-VIII.
1
1c
(
4
4
3
3
Surprisingly less is known about phosphoraneimine and
phosphoraneiminato complexes of rhenium and technetium.
Some pioneering work in this field has been done by Katti
2 7
O
bifunctional ligands on the basis of spectroscopical data, but
no X-ray structural data of any of these complexes could be
et al. They isolated [H
reaction between Me SiNPPh
and reported the formation of the rhenium(VII) phosphor-
2
NPPh
3
4
][ReO ] as the product of a
3
3
and ammonium perrhenate
1
2
provided. Thus, only a few structurally fully characterized
rhenium(V) and rhenium(VI) phosphoraneiminato complexes
are documented. Two of them, tetrakis(thiophenolato)-
1
0
3 3
aneiminate O ReNdPPh by dehydration of the ion pair.
The extension of this approach to technetium gave similar
1
3
99m
11
triphenylphosphoraneiminatorhenium(VI) (I) and bis-
results, when the ‘carrier-free’ Tc was used. Our recent
attempts, to perform reactions between 99Tc-pertechnetate
and Me
gave [H
has been elucidated before. Thermal dehydration did not
3
SiNPPh
3
on a milligram scale, however, exclusively
2
NPPh ][TcO
3
4
], a compound the structure of which
11c
(
5) Katti, K. V.; Roesky, H. W.; Rietzel, M. Z. Anorg. Allg. Chem. 1987,
53, 123.
5
(
6) (a) Roesky, H. W.; Hesse, D.; Rietzel, M.; Noltemeyer, M. Z.
Naturforsch. 1990, 45b, 72. (b) Roesky, H. W.; Hesse, D.; Noltemeyer,
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Naturforsch. 1995, 50b, 1050. (d) Leichtweis, I.; Hasselbring, R.;
Roesky, H. W.; Noltemeyer, M.; Herzog, A. Z. Naturforsch. 1993,
(
2-aminothiophenolato-N,S)triphenylphosphoraneiminator-
1
4
henium(V) (II), are formed during reactions of nitrido
complexes with triphenylphosphine, whereas a dimeric
rhenium(VI) complex with a metal-metal bond (III) is the
4
8b, 1234. (e) Schlecht, S.; Deubel, D. V.; Frenking, G.; Geiseler,
G.; Harms, K.; Magull, J.; Dehnicke, K. Z. Anorg. Allg. Chem. 1999,
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7) Cambridge Crystal Structure Database, Vers. 5.25, update 2, April
004, Cambridge.
8) (a) Grob, T.; Geiseler, G.; Harms, K.; Greiner, A.; Dehnicke, K. Z.
Anorg. Allg. Chem. 2002, 628, 217. (b) Grob, T.; Harms, K.; Dehnicke,
K. Z. Anorg. Allg. Chem. 2001, 627, 1801. (c) Schrumpf, F.; Roesky,
H. W.; Noltemeyer, M. Z. Naturforsch. 1990, 45b, 1600. (d) Stahl,
M.; Faza, N.; Massa, W.; Dehnicke, K. Z. Anorg. Allg. Chem. 1997,
15
6
4 3 3
product of the reaction of ReNCl with Me SiNPPh .
(
(
Here, we present further studies of the reactions of
trimethylsilylated phosphoraneiminates (see Chart 1) with
common rhenium and technetium precursors such as
2
[
NBu
4
][MOCl
4
], [NBu
4 4 3 3 2
][MNCl ], [ReOCl (PPh ) ], and
[MCl
3
(PPh (CH
3
)
2
3
CN)] (M ) Re, Tc) including the X-ray
6
23, 1855. (e) Grun, M.; Harms, K.; Meyer zu K o¨ cker, R.; Dehnicke,
K.; Goesmann, H. Z. Anorg. Allg. Chem. 1996, 622, 1091.
f) R u¨ benstahl, T.; Weller, F.; Dehnicke, K. Z. Kristallogr. 1995, 210,
37. (g) Sarsfield, M. J.; Thornton-Pett, M.; Bochmann, M. J. Chem.
crystal structures of prototype products.
(
5
Experimental Section
Soc., Dalton Trans. 1999, 3329. (h) Cavell, R. C.; Babu, R. P. K.;
Kasani, A.; McDonald, R. J. Am. Chem. Soc. 1999, 121, 5805.
General Considerations. Solvents were dried and used freshly
(
2
i) Gamer, M. T.; Rast a¨ tter, M.; Roesky, P. W. Z. Anorg. Allg. Chem.
002, 628, 2269. (j) Babu, R. P. K.; McDonald, R.; Cavell, R. G.
1
6
distilled unless otherwise stated. [NBu
4
][ReOCl
(CH CN)], [NBu
(CH
4
], [NBu
4
]-
]-
17
18
19
Chem. Commun. 2000, 481. (k) Aparna, K.; Babu, R. P. K.; McDonald,
R.; Cavell, R. G. Angew. Chem. 2001, 113, 4535; Angew. Chem., Int.
Ed. 2001, 40, 4400. (l) Babu, R. P. K.; McDonalds, R.; Cavell, R. G.
Organometallics 2000, 19, 3462. (m) Grun, M.; Weller, F.; Dehnicke,
K. Z. Anorg. Allg. Chem. 1997, 623, 224. (n) Sarsfield, M. J.; Said,
M.; Thornton-Pett, M.; Gerrard, L. A.; Bochmann, M. J. Chem. Soc.,
Dalton Trans. 2001, 822. (o) Aharonian, G.; Feghali, K.; Gambarotta,
S.; Yap, G. P. A. Organometallics 2001, 20, 2616. (p) Aharonian,
G.; Feghali, K.; Gambarotta, G.; Yap, G. P. A. Organometallics 2001,
[ReNCl
TcOCl
4
], [ReOCl
3
(PPh
][TcNCl
3
)
2
], [ReCl
],21 [TcCl
3
(PPh
3
)
2
3
4
20
CN)],22 and
[
4
], [NBu
4
4
3
(PPh
3
)
2
3
(12) Katti, K. V.; Cavell, R. G. Inorg. Chem. 1989, 28, 3033.
(13) Dilworth, J. R.; Neaves, B. D.; Hutchinson, J. P.; Zubieta, J. A. Inorg.
Chim. Acta 1982, 65, L223.
(14) Tsang, B. W.; Reibenspies, J.; Martell, A. E. Inorg. Chim. Acta 1993,
211, 23.
2
0, 5008. (q) Wang, Z.-X.; Li, Y.-X. Inorg. Chem. 2002, 41, 5934.
(15) Nussh a¨ r, D.; Weller, F.; Dehnicke, K. Z. Anorg. Allg. Chem. 1993,
619, 1121.
(16) Alberto, R.; Schibli, R.; Egli, A.; Schubiger, P. A.; Hermann, W. A.;
Artus, G.; Abram, U.; Kaden, T. A. J. Organomet. Chem. 1995, 493,
119.
(17) Abram, U.; Braun, M.; Abram, S.; Kirmse, R.; Voigt, A. J. Chem.
Soc., Dalton Trans. 1998, 231.
(18) Johnson, N. P.; Lock, C. J. L.; Wilkinson, G. Inorg. Synth. 1967, 9,
145.
(
9) (a) Leung, W.-P.; So, C.-W.; Wang, J.-Z.; Mak, T. C. W. Chem.
Commun. 2003, 248. (b) Kasani, A.; McDonald, R.; Cavell, R. G.
Chem. Commun. 1999, 1993. (c) Pingrong, W.; Stephan, D. W.
Organometallics 2002, 21, 1308. (d) Miller, J. S.; Miller, M. O.;
Caulton, K. G. Inorg. Chem. 1974, 13, 1632. (e) Abram, U.;
Hagenbach, A. Z. Anorg. Allg. Chem. 2002, 628, 1719. (f) Bennett,
B. K.; Saganic, E.; Lovell, S.; Kaminsky, W.; Samuel, A.; Mayer, J.
M. Inorg. Chem. 2003, 42, 4127.
(
10) Katti, K. V.; Singh, P. R.; Barnes, C. L.; Katti, K. K.; Kopocka, K.;
Ketring, A. R.; Volkert, W. A. Z. Naturforsch. 1993, 48b, 1381.
11) (a) Katti, K. V.; Singh, P. R.; Katti, K. K.; Volkert, W. A.; Ketring,
A. R. Radiochim. Acta 1994, 66/67, 129. (b) Katti, K. K.; Singh, P.
R.; Volkert, W. A.; Anderson, C. J.; Welch, M. J.; Hoffman, T.; Katti,
K. V.; Ketring, A. R.; Wang, M. Appl. Radiat. Isot. 1995, 46, 53.
(19) Rouschias, G.; Wilkinson, G. J. Chem. Soc. A 1967, 993.
(20) Preetz, W.; Peters, G. Z. Naturforsch. 1980, 35b, 1355.
(21) Baldas, J.; Boas, J. F.; Bonnyman, J.; Williams, G. A. J. Chem. Soc.,
Dalton Trans. 1998, 231.
(22) Pearlstein, R. M.; Davis, W. M.; Jones, A. G.; Davison, A. Inorg.
Chem. 1989, 28, 3332.
(
Inorganic Chemistry, Vol. 44, No. 9, 2005 3173

Hecht et al.
Me
Ph
3
SiNPPh 23
)CH PPh
3
were prepared by standard procedures. Me
3
SiNP-
to give a pale orange-red solution from which slowly deposited
(
2
2
2
was synthesized by a modification of the general
hexagonal plates of [ReNCl
obtained as a brick-red powder by concentrating the mother liquor.
Yield: 90%. Elemental analysis. Calcd for C36 Cl Re C:
2 3 2
(PPh ) ]. More product could be
24
route previously published by Appelt and Ruppert.
Radiation Precautions. 99Tc is a weak â -emitter. All manipu-
lations with this isotope were performed in a laboratory approved
for the handling of low-level radioactive materials. Normal
glassware provides adequate protection against the low-energy beta
emission of the technetium compounds. Secondary X-rays (brems-
strahlung) play an important role only when larger amounts of
-
H30NP
2
2
54.3, H: 3.8, N: 1.8. Found C: 54.5, H: 3.6, N: 1.8%. The infrared
spectrum of the compound and the unit cell dimensions of the
2
6
single-crystals were identical with those published previously.
[ReOCl (Ph PCH PPh N)] (4). Ph P(NSiMe )CH PPh
2
2
2
2
2
2
3
2
2
(47 mg, 0.1 mmol) and [NBu ][ReOCl ] (59 mg, 0.1 mmol) were
4
4
99
Tc are used.
dissolved each in 1 mL of absolutely dry acetonitrile, and the ligand
was added dropwise to the rhenium precursor. The color of the
Infrared spectra were measured as KBr pellets on a Shimadzu
FTIR-spectrometer. FAB mass spectra were recorded with a TSQ
+
solution changed to blue and light blue crystals of [ReOCl
(Ph PCH PPh N)] ‚2 CH CN slowly separated upon storing at
-20 °C. Yield: 56 mg (83%). Elemental analysis. Calcd for
Cl Re C: 45.5, H: 3.5, N: 3.9. Found C: 45.3, H:
3.5, N: 3.8%. IR: M-N-P 1117 (m), NdP 986 (m), RedO 943
2
-
(Finnigan) instrument using a nitrobenzyl alcohol matrix (results
2
2
2
2
3
are given in the form: m/z, % of base peak (B), assignment).
Elemental analysis of carbon, hydrogen, nitrogen, and sulfur were
determined using a Heraeus vario EL elemental analyzer. The
technetium analyses were done by liquid scintillation counting.
NMR-spectra were taken with a JEOL 400 MHz multinuclear
spectrometer.
C
54
H
50
N
4
O P
4 2 4
2
-
1
1
cm (m). H NMR (CD
(tr, JP-H 12 Hz, 2H, CH
(NPPh CH ), 21.3 d (CH
3
CN): δ ) 8.5-6.9 (m, 20H, phenyl), 3.3
) ppm. 31P NMR (CD
CN): δ ) 81.7 d
PPh ) ppm. The dimeric complex did
2
3
2
2
2
2
[
ReNCl(Ph
104 mg, 0.22 mmol) was dissolved in 5 mL of acetonitrile and
added to [NBu ][ReNCl ] (58 mg, 0.1 mmol) in a small amount of
2
PCH
2
PPh
2
NH)
2
]Cl (1). Ph
2
P(NSiMe
3
)CH
2
PPh
2
not give satisfactory mass spectra.
(
[TcNCl (HNPPh ) ] (5). [NBu ][TcOCl ] (50 mg, 0.1 mmol)
2
3 2
4
4
4
4
2 2 3 3
was dissolved in 2 mL of CH Cl and mixed with Me SiNPPh
acetonitrile. The color of the solution turned brown upon stir-
ring at room temperature for 30 min. Yellow columns of
2 2
(140 mg, 0.4 mmol) in 1 mL of CH Cl . The solution was stirred
at room temperature for 30 min. During this time, the color changed
to yellow-brown. Large yellow crystals of [TcNCl (HNPPh ) ]
[
ReNCl(Ph
lution after standing overnight in a refrigerator. Yield: 83 mg
78%). Elemental analysis. Calcd for C56 Cl Re C: 56.3,
H: 4.6, N: 7.0. Found C: 56.2, H: 4.5, N: 6.8%. IR: NH 3050
2
PCH
2
PPh
2
NH)
2
3
]Cl‚3CH CN precipitated from this so-
2
3 2
deposited together with a small amount of colorless HNPPh and
3
(
H
55
N
6
2
P
4
a blue, technetium-containing oil after overlayering with 5 mL of
n-hexane. The side products could be removed by rinsing with a
-
1
(
m), M-N-P 1114 (m), RetN 1065 (m), NdP 991 cm
.
small amount of cold CH Cl . Yield: 37 mg (50%). Elemental
2
2
1
H NMR (CD
NH), 3.13 (tr, JP-H 12 Hz, 2H, CH
δ ) 59.39 d (NPPh CH
034, 12% B, ([ReNCl(Ph
3
CN): δ ) 8.3-6.9 (m, 20H, phenyl), 6.35 (s, 1H,
36 34 3 2 2
analysis. Calcd for C H N Cl OP Tc: Tc 13.1. Found Tc: 13.2%.
) ppm. 31P NMR (CD
CN):
2
3
IR: NH 3025 (m), M-N-P 1135 (m), TctN 1070 (m), NdP
+
-1
2
2
), 18.14 d (CH
CH PPh
2
PPh
NH)
2
). FAB MS: m/z )
940 cm . The solubility of the complex prevented the detection
+
1
2
2
2
2
] ); 998, 25% B,
of NMR spectra of sufficient quality.
+
+
(
[ReN(Ph
ReN(OSiMe
PPh (236 mg, 0.25 mmol) and [NBu
2
CH
2
PPh
2
NH)
2
] ); 400, 15% B, ([Ph
PPh NH) ]Cl (2). Ph
][ReOCl ] (59 mg, 0.1 mmol)
2
CH
2
PPh
2
NH] ).
[
TcNCl
70 mg, 0.15 mmol) in 1 mL of THF was added to a solution of
NBu ][TcNCl ] (50 mg, 0.1 mmol) in 2 mL of THF. The color of
2 2 2 2 2 3 2 2
(Ph PCH PPh NH)] (6). Ph P(NSiMe )CH PPh
[
3
)(Ph
2
PCH
2
2
2
2 3 2
P(NSiMe )CH -
(
[
2
4
4
4
4
were dissolved each in 1 mL of acetonitrile, and the ligand was
slowly added to the rhenium precursor. The color of the solution
changed from yellow to blue and slowly turned to brown when the
addition was finished. The solution was stored in a refrigerator
overnight. This resulted in deposition of yellow needles of [ReN-
the solution changed to dark brown upon stirring at room temper-
ature for 30 min. Standing overnight in a refrigerator resulted in
an orange-red solution, from which an orange-red solid deposited.
Recrystallization from acetonitrile gave orange plates. Yield:
3
0 mg (52%). Elemental analysis. Calcd for C25
23 2 2 2
H N Cl P Tc:
(
OSiMe
emental analysis. Calcd for C53
N: 3.7. Found C: 56.0, H: 4.9, N: 3.8%. IR: NH 2858 (m),
3
)(Ph
2
PCH
2
PPh
2
NH)
2
]Cl‚H
2
O. Yield: 64 mg (57%). El-
Tc 17.0. Found Tc: 17.1%. IR: NH 3485 (m), M-N-P 1115 (m),
H
55
N
3
ClO ReSi C: 55.8, H: 4.8,
2
P
4
-1 1
TctN 1085 (m), NdP 970 cm . H NMR (CD
3
CN): δ ) 8.0-
6
.6 (m, 20H, phenyl), 6.4 (s, 1H, NH), 3.98 (tr, JP-H 12 Hz, 2H,
-
1 1
M-N-P 1119 (m), RetN 1060 (m), NdP 964 cm . H NMR
31
CH
2
) ppm. P NMR (CD
PPh ).
TcNCl(Ph PCH
104 mg, 0.22 mmol) in 1 mL of acetonitrile was added to a solution
of [NBu ][TcNCl ] (50 mg, 0.1 mmol) in 5 mL of the same solvent.
3
CN): δ ) 60.3 d (NPPh
2 2
CH ), 31.7
(
(
(
CD
tr, JP-H 12 Hz, 4H, CH
CD CN): δ ) 37.51 d (NPPh
3
CN): δ ) 8.5-6.7 (m, 40H, phenyl), 6.25 (s, 2H, NH), 3.14
broad (CH
2
2
) ppm. 31P NMR
2
), 0.02 (s, 9H, CH
3
[
2
2
PPh
2
NH)
2
]Cl (7). Ph
2
P(NSiMe
3
)CH
2 2
PPh
+
3
2 2
CH ), 25.54 d (CH
2
PPh
PPh
2
). FAB
(
+
MS: m/z ) 1089, 10% B, ([ReN(OSiMe
9
PPh
3
)(Ph
2
CH
2
2
NH)
2
] );
4
4
+
99, 70% B, ([ReN(Ph
2 2
CH PPh
2
NH)
2
] ); 400, 40% B, ([Ph
2
CH
2
-
The solution was stirred at room temperature for 30 min, and the
volume was reduced in a vacuum to about 1 mL. Yellow crystals
+
2
NH] ).
[
ReNCl
was suspended in CH
70 mg, 0.2 mmol) was added. The solid slowly dissolved upon
heating under reflux to give a clear, dark-brown solution. Cooling
overnight resulted in the precipitation of red crystals of [ReNCl
PPh ]. More product was obtained by concentration and cooling
of the mother liquor. Yield: 65%. (b) [ReCl (PPh (CH CN)]
87 mg, 0.1 mmol) was suspended in acetonitrile, Me SiNPPh
70 mg, 0.2 mmol) was added, and the mixture was heated to reflux
2
(PPh
3
)
2
] (3). (a) [ReOCl
3
(PPh
3
)
2
] (83 mg, 0.1 mmol)
of [TcNCl(Ph
overnight. Yield: 85 mg (80%). Elemental analysis. Calcd for
Cl Tc: Tc 9.3. Found Tc: 8.5%. IR: NH 3051 (s),
M-N-P 1115 (m), TctN 1050 (m), NdP 995 cm . H NMR
2 2 2 2 3
PCH PPh NH) ]Cl‚2CH CN deposited upon standing
2
Cl or acetonitrile (20 mL), and Me
2
3
SiNPPh
3
(
C
54
H
52
N
5
2 4
P
-1
1
2
-
(
(
(
CD
tr, JP-H 12 Hz, 2H, CH
NPPh CH ), 37.8 very broad (CH
3
CN): δ ) 8.0-6.8 (m, 20H, phenyl), 6.3 (s, 1H, NH), 3.12
(
3
)
2
31
2
) ppm. P NMR (CD
3
CN): δ ) 52.1 d
3
3
)
2
3
2
2
2
PPh ).
2
(
(
3
3
(
25) G. M. Sheldrick, SHELXS-97 and SHELXL97 - programs for the
solution and refinement of crystal structures. G o¨ ttingen, Germany,
1997.
(
(
23) Birkhofer, L.; Ritter, A.; Kim, S. M. Chem. Ber. 1963, 96, 3099.
24) Appel, R.; Ruppert, I. Z. Anorg. Allg. Chem. 1974, 406, 131.
(26) Doedens, R. J.; Albers, J. Inorg. Chem. 1967, 6, 204.
3174 Inorganic Chemistry, Vol. 44, No. 9, 2005

Re(V) and Tc(V) Complexes with Phosphoraneimines
Table 1. X-ray Structure Data Collection and Refinement Parameters
(1)‚3CH3CN
(2)‚H2O
(4)‚2CH3CN
(5)
(6)‚H2O
(7)‚2CH3CN
formula
C56H55Cl2N6P4Re
1193.04
monoclinic
18.104(5)
15.186(5)
19.813(5)
90
C53H55Cl N3O2P4ReSi
1139.62
orthorhombic
15.041(1)
16.791(1)
21.456(4)
90
C54H50Cl4N4O2P4Re2
1425.1
C25H23Cl2N2P2Tc
582.29
monoclinic
19.476(5)
16.582(5)
16.227(5)
90
C36H34Cl2N3OP2Tc
755.50
monoclinic
25.666(5)
9.236(1)
31.073(4)
90
C54H52Cl2N5P4Tc
1063.79
monoclinic
12.487(3)
17.115(4)
25.060(7)
90
Mw
crystal system
triclinic
10.783(1)
11.320(2)
11.939(2)
76.52(1)
73.63(1)
77.43(1)
1341.6(3)
P1h
a/Å
b/Å
c/Å
R/°
â/°
96.72(1)
90
90
100.48(1)
90
102.28(1)
90
98.36(1)
90
γ/°
V/Å
90
3
5410(3)
P21/n
5419(1)
P212121
4
5153(3)
P21/c
7197(2)
C2/c
5299(2)
P21/n
space group
Z
4
1
8
8
4
-
3
Dcalc/g cm
1.465
1.397
2.473
1.764
1.501
1.394
1.333
-
1
µ/mm
2.506
4.871
0.906
0.669
0.533
no. of reflections 66109
13256
6777
36192
8926
31775
no. independent
no. parameters
R1/wR2
GOF
device/temp/K
16465
633
11743
5831
8040
595
7790
12184
586
317
420
855
a
0.0265/0.0632
1.029
Bruker Smart/193 CAD4/293
0.0434/0.1091
1.128
0.0289/0.0692
1.080
0.0671/0.1432
1.104
Bruker Smart/293 CAD4/293
0.0549/0.1359
0.987
0.0410/0.0823
0.901
CAD4/293
Bruker Smart/193
a
R1 ) |Fo - Fc|/|Fo|; wR2 ) [w(Fo - Fc ) /(wFo )]-1/2.
2
2 2
2
-
[
TcNCl
2
(PPh
3
)
2
] (8). [TcCl
3
(PPh
3
)
2
(CH
3
CN)] (77 mg, 0.1 mmol)
3
(70 mg, 0.2 mmol) was
technetium precursors such as [ReOCl (PPh ) ], [MOCl ] ,
3
3 2
4
was suspended in acetonitrile, Me
added, and the mixture was heated to reflux for 30 min to give a
pale orange-red solution from which hexagonal plates of
TcNCl (PPh ) ] slowly deposited. More of the sparingly soluble
2 3 2
product could be obtained as a brick-red powder by concentrating
the mother liquor. Yield: 90%. Elemental analysis. Calcd for
3
SiNPPh
3 3 2 3
or [MCl (PPh ) (CH CN)] (M ) Re, Tc) with an excess of
trimethylsilylphosphoraneiminates result in cleavage of the
PdN bond and the formation of nitrido complexes.
[
[
ReOCl
dichloromethane or acetonitrile, and red crystals of the nitrido
species [ReNCl (PPh ] deposit after cooling and concentra-
3 3 2 3 3
(PPh ) ] dissolves in solutions of Me SiNPPh in
2
3 2
)
C
36
H
30NP
2
Cl
2
Tc Tc: 14.0. Found C: Tc: 14.2%. The infrared
27
tion of the reaction mixture. The reaction follows the general
route given in eq 1.
spectrum was identical with that published previously.
X-ray Crystallography. The intensities for the X-ray determina-
tions were collected on an automated single-crystal diffractometer
of the type CAD4 (Enraf Nonius) or on a SMART CCD (Bruker)
with Mo KR radiation (λ ) 0.71073 Å). Standard procedures were
applied for data reduction and absorption correction. Structure
[ReOCl (PPh ) ] + Me SiNPPh f
3
3 2
3
3
[
ReNCl (PPh ) ] + OPPh + Me SiCl (1)
2 3 2 3 3
solutions and refinements were performed with SHELXS97 and
SHELXL97.25 Hydrogen atom positions were calculated for ideal-
The formation of OPPh and CH SiCl was detected by
P and H NMR, and the resulting [ReNCl (PPh ) ] was
2 3 2
characterized by elemental analysis, IR-spectra, and X-ray
crystallography. Surprisingly, the same product was isolated
3
3
3
1
1
ized positions and treated with the ‘riding model’ option of
SHELXL, except of those H-atoms, which are bonded to nitrogen
atoms and/or involved in hydrogen bonds. Their positions were
derived from the final Fourier maps and refined. More details on
data collections and structure calculations are contained in
Table 1.
from reactions of the rhenium(III) complex [ReCl
CH CN)] with Me SiNPPh . Obviously, oxidation of the
metal atom is performed by the (reductive) release of PPh
from the phosphoraneiminate. This is strongly suggested by
the detection of uncoordinated PPh in the reaction mixture
after precipitation of the sparingly soluble [ReNCl (PPh
3 3 2
(PPh ) -
(
3
3
3
3
Additional information on the structure determinations have been
deposited with the Cambridge Crystallographic Data Centre.
3
2
3 2
) ]
Results and Discussion
when the reaction is carried out in dry solvents and under
exclusion of air. The same type of reaction proceeds when
Trimethylsilylphosphoraneiminates are excellent starting
materials for the preparation of metal complexes containing
phosphoraneiminato ligands. This has been demonstrated for
3 3 2 3
the analogous technetium precursor, [TcCl (PPh ) (CH CN)],
is used, and [TcNCl (PPh ] can be isolated in good yields.
2
3 2
)
1
,2
a large number of main group and transition metals. The
ready formation of trimethylchlorosilane or hexamethyl-
disiloxane is regarded as the driving force of these reactions
when they start from appropriate chloro or oxo complexes.
Surprisingly, this general route does not fully apply for
rhenium and technetium compounds. Despite the fact, that
there exist some rare examples of rhenium phosphoraneimi-
nato complexes containing the metal in the oxidation states
The identity of the product was confirmed by its infrared
spectrum and an X-ray structure analysis, which was identical
2
8
with that previously determined. The high stability of the
triple bonds between nitrogen and technetium or rhenium is
most probably the driving force for the decomposition of
the phosphoraneiminate and the formation of nitrido ligands.
Similar formations of MtN bonds (M ) Re, Tc) have been
observed during the decomposition of other nitrogen-
“
+7”, “+6”, and “+5”, reactions of common rhenium and
29
30
containing species such as dithiocarbazates, benzamidines,
(
27) Kaden, L.; Lorenz, B.; Schmidt, K.; Sprinz, H.; Wahren, M. Isotopen-
praxis 1981, 17, 174. (b) Baldas, J.; Bonnyman, J.; Williams, G. A.
J. Chem. Soc., Dalton Trans. 1984, 833.
(28) Gernert, M. B.; Hiller, W.; Dilworth, J. R.; Parrott, S. J. Z. Kristallogr.
1995, 210, 961.
Inorganic Chemistry, Vol. 44, No. 9, 2005 3175

Hecht et al.
Figure 1. Ellipsoid representation36 of [TcNCl2(HNPPh3)2] (5). Thermal
ellipsoids represent 50% probability. Hydrogen atoms at carbon atoms are
omitted for clarity.
Table 2. Selected Bond Lengths (Å) and Angles (deg) in
Figure 2. Ellipsoid representation36 of the complex cation of 1. Thermal
ellipsoids represent 50% probability. Hydrogen atoms at carbon atoms are
omitted for clarity.
[TcNCl2(HNPPh3)2] (5)
Tc-N10
1.589(4)
2.388(1)
2.102(4)
1.593(4)
105.0(2)
104.4(2)
148.81(5)
82.5(1)
Tc-Cl1
Tc-N1
N1-P1
2.389(1)
2.078(4)
1.601(4)
Tc-Cl2
Tc-N2
N2-P2
the yield of 5 can be increased by the addition a small
amounts of water. Compound 6 is formed as the major
product of the reaction of [NBu ][TcOCl ] with Me SiNPPh
4 4 3 3
when dichloromethane is used as solvent. Decomposition of
the solvent is the source of the protons in such reactions as
N10-Tc-Cl1
N10-Tc-N1
Cl1-Tc-Cl2
Cl1-Tc-N2
Cl2-Tc-N2
Tc-N1-P1
N10-Tc-Cl2
N10-Tc-N2
Cl1-Tc-N1
Cl2-Tc-N1
N1-Tc-N2
Tc-N2-P2
106.2(2)
105.4(2)
89.2(1)
82.5(1)
150.2(2)
134.8(3)
89.9(1)
133.7(3)
has been checked by a corresponding reaction in CD
2 2
Cl .
phenylhydrazine, azides,17,32 and isothiocyanato or thioni-
3
1
[TcNCl (HNPPh ] is an air-stable yellow solid, which
2
3 2
)
trosyl ligands.33,34
is only sparingly soluble in organic solvents. Therefore, no
NMR spectra of reasonable quality could be obtained. The
TctN vibration in the IR spectrum of the compound is
We were not able to isolate products that are formed by
ligand exchange of triphenylphosphine by triphenylphos-
phoraneiminate or triphenylphosphoraneimine during the
-1
clearly resolved at 1070 cm . Figure 1 shows the molecular
structure of 5, selected bond lengths are contained in Table
. The technetium atom is five-coordinate, and its coordina-
tion sphere can best be described as a square pyramid with
the nitrido nitrogen atom as apex. The basal plane of the
pyramid is formed by the chloro ligands and the nitrogen
atoms of the phosphoraneimines. They are coplanar within
above-mentioned attempts. The reaction of [NBu
with Me SiNPPh in CH Cl , however, forms the technetium-
V) nitrido complex [TcNCl (HNPPh ] (5) in reasonable
4 4
][TcOCl ]
2
3
3
2
2
(
2
3 2
)
yields as has been reported previously in a short communica-
tion.35 More detailed studies of the course of the reaction
-
and a comparison with reactions of [ReOCl
Me SiNP(Ph )CH PPh
is the coordination of a phosphoraneiminato ligand that
rapidly loses PPh and converts to a nitrido species. This is
clearly indicated by the formation of the paramagnetic
NBu ][TcNCl ]. This compound is isolated as orange red
4
]
with
0
.053(2) Å (rms 0.0536). The Tc atom is displaced from
this plane by 0.589(2) Å toward N10. This contrasts the
bonding situation of [TcNCl (PPh ], where the coordination
sphere of the metal is strongly distorted toward a trigonal
3
2
2
2
(vide infra) suggest that the first step
2
3 2
)
3
2
8
bipyramid with the phosphines as axial ligands. The Tc-
[
4
4
N10 bond length of 1.589(4) Å belongs to the shortest
crystals as the sole product when the reaction is performed
in carefully dried acetonitrile. It can doubtlessly be identified
by its EPR and IR spectra. No other product could be isolated
from such reaction mixtures as long as moisture was carefully
excluded. Standing of such reaction mixtures, that contain
an excess of Me SiNPPh for a prolonged time, however,
3 3
results in the formation of the triphenylphosphoraneimine
technetium(V) complex (5). The rate of this reaction and
7
technetium-nitrogen triple bonds that have been observed.
-
4
Shorter TctN bonds were only observed for two [TcNCl ]
3
7
salts, a dithiocarbamato/dithiooxalato mixed-ligand com-
plex and a complex cation with 1,4,8,11-tetrathiacyclo-
decadecane (1.581 Å). The phosphoraneimine ligands in
are in trans-arrangement, and the corresponding Tc-N
3
8
3
9
5
bond lengths indicate single bonds as is observed for other
9
donor-acceptor complexes of the same type. The spectro-
(
29) Duatti, A.; Marchi, A.; Pasqualini, R. J. Chem. Soc., Dalton Trans.
scopically detected protonation of N1 and N2 is supported
by Tc-N-P angles of 133.7(3) and 134.8(3)° and the
localization of the corresponding hydrogen atom positions
in the final Fourier maps.
1990, 3729.
(
30) Abram, U.; Wollert, R. Radiochim. Acta 1993, 63, 149.
(31) (a) Chatt, J.; Falk, C. D.; Leigh, G. J.; Paske, R. J. J. Chem. Soc. A
1969, 2288. (b) Baldas, J.; Bonnyman, J.; Pojer, P. M.; Williams, G.
A.; Mackay, M. F. J. Chem. Soc., Dalton Trans. 1981, 1798.
32) (a) Baldas, J.; Bonnyman, J.; Williams, G. A. J. Chem. Soc., Dalton
Trans. 1984, 2395. (b) Abram, U.; K o¨ hler, K.; Kirmse, R.; Kali-
nochenko, N. B.; Marov, I. N. Inorg. Chim. Acta, 1990, 176, 139.
33) Bonfada, E.; Abram, U.; Str a¨ hle, J. Z. Anorg. Allg. Chem. 1998, 624,
An excess of the chelating phosphoraneimine Me
(Ph )CH PPh readily reacts with [NBu ][ReOCl
NBu ][ReNCl
ligands and formation of air-stable, cationic rhenium(V)
3
SiNP-
(
2
2
2
4
4
] and
[
4
4
] under exchange of the equatorial chloro
(
757.
3176 Inorganic Chemistry, Vol. 44, No. 9, 2005

Re(V) and Tc(V) Complexes with Phosphoraneimines
complexes. The products contain Ph PCH PPh NH ligands
Table 3. Selected Bond Lengths (Å) and Angles (deg) in the Rhenium
Nitrido Complexes (1), (2) and Their Technetium Analogue (7)
2
2
2
when moisture is not carefully excluded during the entire
-
reaction, and the replacement of the oxo ligand of [ReOCl
4
]
(1)
(2)
(7)
3-
by an “N ” ligand is obtained as has been observed for the
M-N10
1.666(2)
2.715(1)
2.110(2)
2.084(2)
2.432(1)
2.432(1)
1.596(2)
1.605(2)
1.793(2)
1.840(2)
1.805(3)
1.848(2)
168.69(7)
102.35(9)
106.34(9)
92.92(7)
94.29(7)
120.1(1)
125.4(1)
105.3(1)
108.3(1)
103.38(8)
84.69(6)
105.8(1)
108.0(1)
102.84(8)
83.56(6)
81.73(8)
1.690(4)
1.952(4)
2.071(5)
2.055(5)
2.496(2)
2.485(2)
1.598(5)
1.611(6)
1.796(6)
1.828(6)
1.795(7)
1.823(7)
165.6(2)
98.3(2)
1.620(3)
2.715(1)
2.103(3)
2.106(3)
2.417(1)
2.462(1)
1.586(3)
1.587(3)
1.808(3)
1.846(3)
1.794(3)
1.838(3)
164.1(1)
105.8(1)
104.3(1)
91.9(1)
-
M-Cl1/O
reaction of [ReOCl
4
] with Me
3
SiNPPh
3
. The isolation of
M-N1
an oxo complex, however, is successful when equimolar
amounts of [NBu ][ReOCl ] and Me SiNP(Ph )CH PPh and
absolutely dry solvents are used.
The rhenium(VI) center is reduced during reactions with
NBu ][ReNCl ], and the formation of the rhenium(V)
M-N2
4
4
3
2
2
2
M-P2
M-P21
N1-P1
N2-P11
[
4
4
P1-C10
P2-C10
2 2 2 2
complex [ReNCl(Ph PCH PPh NH) ]Cl (1) can be described
P11-C20
by eq 2.
P21-C20
N10-M-Cl/O
N10-M-N1
N10-M-N2
N10-M-P2
N10-M-P21
M-N1-P1
M-N2-P11
N1-P1-C10
P1-C10-P2
C10-P2-M
N1-M-P2
N2-P11-C20
P11-C20-P21
C20-P21-M
N2-M-P21
N1-M-N2
99.3(2)
86.9(2)
89.7(2)
91.7(1)
125.2(3)
126.2(3)
105.6(3)
110.0(3)
102.0(2)
83.6(1)
105.3(3)
108.7(3)
99.7(2)
127.6(2)
125.9(2)
106.2(2)
107.0(2)
103.9(1)
79.30(8)
106.2(2)
110.8(2)
101.5(1)
83.30(8)
83.6(1)
]- in dry acetonitrile do
4
Attempted reactions of [ReNCl
82.3(2)
84.9(2)
not give the same product. No reaction was observed at
ambient conditions or with slight heating, and prolonged
heating under reflux results in decomposition of the phos-
phoraneimine and the formation of a variety of rhenium-
Information. The Re-N1 and Re-N2 bond lengths of
2.110(2) and 2.084(2) Å clearly indicate a rhenium-nitrogen
single bond and the presence of a donor-acceptor type
complex. This is also supported by the Re-N-P angles,
which are close to 120°. Whereas the P2-C10 and
P21-C20 bond lengths are in the typical range, the P1-
C10 and P11-C20 bonds (1.793(2) and 1.805(3) Å) are
slightly shortened. This indicates some delocalization of
electron density over the phosphoraneimine phosphorus
atoms.
(VI) species, as determined by EPR spectroscopy of the
reaction mixtures. We were not able to isolate and character-
ize defined products from the resulting dark brown solutions.
Single crystals of an acetonitrile solvate of 1 are obtained
3
by slow evaporation of a CH CN solution of the complex.
They decompose slowly by the loss of solvent to give a
yellow powder. NMR and IR spectroscopic results confirm
the diamagnetism of the product and the protonation of the
nitrogen atoms. The coordination environment of rhenium
A similar bonding situation is found in the [ReN-
+
+
in the [ReNCl(Ph
octahedron with the Ph
2
PCH
2
PPh
2
NH)
PPh
2
]
cation is a distorted
(OSiMe
when [NBu
CH PPh according to eq 3.
3
)(Ph
2
PCH
2
PPh
2
NH)
2
]
cation, which is formed
P(NSiMe )-
2
PCH
2
2
NH igands in cis-arrange-
4
][ReOCl
4
] reacts with an excess of Ph
2
3
ment (Figure 2). Selected bond lengths and angles are
summarized in Table 3. The Re-Cl bond of 2.715(1) Å is
markedly elongated by the considerable trans influence of
2
2
3-
the strong σ-donor “N ” ligand. Two different angles
between the nitrido nitrogen atom and the equatorial donor
atoms are observed (92.92(7) and 94.29(7)° to the phosphine
donors, 102.35(9) and 106.34(9)° to the imine nitrogen
atoms). This may not primarily be attributed to different
sterical requirements of these moieties, but to the fact that
the imine hydrogen atoms H1 and H2 are involved in
-
hydrogen bonds to the counterion Cl . More details are
contained in Figure S1 and Table S1 of the Supporting
The trimethylsiloxo ligand is product of the attack of a
released {Me Si} residue to the oxo ligand of the starting
complex. Figure 3 depicts an ellipsoid representation of the
(
34) Abram, U.; H u¨ bner, R.; Wollert, R.; Kirmse, R.; Hiller, W. Inorg.
3
Chim. Acta 1993, 206, 9.
(35) Abram, U.; Hagenbach, A. Z. Anorg. Allg. Chem. 2002, 628, 1719.
(36) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.
(37) Baldas, J.; Colmanet, S. F.; Williams, G. A. Chem. Commun. 1991,
cation. Selected bond lengths and angles are compared with
+
the corresponding values in [ReNCl(Ph
2
PCH
2
PPh
2
NH)
2
] in
954.
(38) Baldas, J.; Boas, J. F.; Colmanet, S. F.; Williams, G. A. J. Chem.
Soc. Dalton Trans. 1992, 2845.
Table 3. Similar to the situation in the chloro derivative, the
N10-Re-N(imine) bond angles are larger than the
N10-Re-P angles and some delocalization of electron
(39) Pietzsch, H.-J.; Spies, H.; Leibnitz, P.; Reck, G. Polyhedron 1993,
12, 2995.
Inorganic Chemistry, Vol. 44, No. 9, 2005 3177

Hecht et al.
Table 4. Selected Bond Lengths (Å) and Angles (deg) in
ReOCl2(µN-Ph2PCH2PPh2N)]2 (4)a
[
Re-O
1.679(3)
2.546(1)
2.028(3)
1.612(3)
1.835(4)
94.7(1)
Re-Cl1
Re-P2
2.422(1)
2.446(1)
2.081(3)
1.817(4)
Re-Cl2
Re-N1
Re-N1′
P1-C10
N1-P1
P2-C10
O-Re-Cl1
O-Re-P2
O-Re-N1′
Re-N1-P1
P1-C10-P2
N1-Re-P2
O-Re-Cl2
O-Re-N1
Re-N1-Re′
N1-P1-C10
Re-P2-C10
Re......Re′
167.5(1)
102.4(2)
103.9(2)
108.0(2)
100.8(1)
3.235(1)
92.5(1)
103.9(2)
122.6(2)
109.1(2)
87.0(1)
a
Symmetry operation: (′) 1 - x, 2 - y, 2 - z.
2
-
rather than an “O ” one, and the molecular ion of the
+
complex cation could be detected at m/z ) 1089 in the FAB
Figure 3. Ellipsoid representation36 of the complex cation of 2. Thermal
ellipsoids represent 30% probability. Hydrogen atoms at carbon atoms are
omitted for clarity.
mass spectrum.
A rhenium(V) complex with an oxo ligand can be isolated
when equimolar amounts of [NBu
4 4 2
][ReOCl ] and Ph P-
(
NSiMe )CH PPh are used and the reaction is performed
3
2
2
in carefully dried acetonitrile (eq 4).
The color of the solution then turns blue and bright blue
Figure 4. Ellipsoid representation36 of 4. Thermal ellipsoids represent 50%
probability. Hydrogen atoms are omitted for clarity.
crystals of [ReOCl
2
2 2 2 2
(µ-N-Ph PCH PPh N)] (4) precipitate
upon concentration. The solid product is stable on air after
isolation and can be redissolved in dry solvents without
decomposition. Access of moisture to the reaction mixture,
however, results in an immediate change of color and the
formation of various phosphoraneimine products. This is
density from the PdN double bonds to the P-C10 and
P-C20 bonds is observed. The imine nitrogen atoms and
the chloride counterion are linked by hydrogen bonds as has
been observed for 1. Details are given in Fig. S2 and Table
S2.
3
1
indicated by the appearance of various P NMR signals in
the range between 35 and 45 ppm in such reaction mixtures,
whereas the phosphoraneiminato phosphorus atom in 4 shows
a resonance at 81.7 ppm. The oxo band in the infrared
spectrum of the dimeric complex can be assigned at
A remarkable feature is the Re-N10 bond length of
1
(
.690(4) Å, which is somewhat longer than in [ReNCl-
+
Ph
2
2
PCH PPh
2
NH)
2
] , and the fact that the Re-O bond of
1.952(4) Å is shorter than expected for a rhenium-oxygen
-1
9
43 cm , which is in the typical range of monooxo rhenium-
single bond despite the expected lengthening by the well-
documented trans-influence of nitrido ligands (see also the
discussion vide supra concerning the unexceptionally long
Re-Cl bond in 1). This indicates partial double bond
character and transfer of π-electron density from the RetN
bond to the trans-situated Re-O bond. This has previously
been observed for a number of oxorhenium complexes with
(V) complexes.
2 2 2
An X-ray structure analysis of [ReOCl (µ-N-Ph PCH -
PPh
2 2
N)] confirms the dimeric character of the complex
(Figure 4). The rhenium atoms are linked by two phospho-
raneiminato functionalities in an almost symmetric fashion
with Re-N1 bond lengths of 2.028(3) and 2.081(6) Å. The
molecular structure has inversion symmetry with the center
of inversion in the center of the resulting four-membered
40
trans-bonded alkoxo ligands and a few examples of imido
complexes.41 For nitrido species, however, it is without
{
Re
2 2
N } ring. Selected bond lengths and angles are sum-
precedent.
marized in Table 4. There are no significant differences in
The presence of a nitrido ligand, which cannot doubtlessly
be derived from the X-ray structural data, is concluded from
the spectroscopic results and the elemental analysis of the
product. The RetN frequency in the IR spectrum of the
(
40) Abram, S.; Abram, U.; Schulz Lang, E.; Str a¨ hle, J. Acta Crystallogr.
995, C51, 1078 and references therein.
(41) (a) Witter, U.; Str a¨ hle, J.; Abram, U. Z. Anorg. Allg. Chem. 1995,
1
6
21, 1338. (b) Witter, U.; Str a¨ hle, J.; Abram, U. Z. Anorg. Allg. Chem.
-
1
compound can be assigned at 1060 cm , the diamagnetism
1997, 623, 218. (c) Yam, W.-W. V.; Tam, K.-K.; Cheung, K.-K. J.
3-
of the complex indicates the presence of an “N ” ligand
Chem. Soc., Dalton Trans. 1995, 2779.
3178 Inorganic Chemistry, Vol. 44, No. 9, 2005

Re(V) and Tc(V) Complexes with Phosphoraneimines
Figure 6. Ellipsoid representation36 of the complex cation of 7 with the
hydrogen bonds between the nitrogen atoms and the chloride counterion
(N1-H1 0.86, H1-Cl2 2.51, N1-Cl2 3.322(3) Å, N1-H1-Cl2 157.7°;
Figure 5. Ellipsoid representation36 of 6. Thermal ellipsoids represent 50%
probability. Hydrogen atoms of carbon atoms are omitted for clarity.
N2-H2 0.86, H2-Cl2 2.38, N2-Cl2 3.225(3) Å, N2-H2-Cl2 167.4°).
Thermal ellipsoids represent 50% probability. Hydrogen atoms of carbon
atoms are omitted for clarity.
Table 5. Selected Bond Lengths (Å) and Angles (deg) in
[
TcNCl2(Ph2PCH2PPh2NH)] (6) (values for two crystallographically
independent species)
nitrogen atom as its apex. The metal is located approximately
0
.56 Å above the basal plane. The bonding situation inside
Tc-N10
Tc-Cl2
Tc-P2
1.612(7)/1.620(8) Tc-Cl1
2.411(2)/2.405(2)
2.077(7)/2.095(7)
1.606(7)/1.608(7)
1.838(7)/1.826(8)
2.409(2)/2.413(2) Tc-N1
2.372(2)/2.364(2) N1-P1
1.804(7)/1.811(8) P2-C10
the chelate ring is similar to those described previously for
the rhenium complexes. The imine nitrogen atoms in both
independent molecules are protonated and form hydrogen
bonds to each one chloro ligand of a neighboring molecule.
This results in the formation of H-bonded dimeric units in
the solid-state structure of the compound. Details are
contained in Table S3 and Figure S3.
P1-C10
N10-Tc-Cl1 109.9(3)/102.3(3) N10-Tc-Cl2 106.1(3)/114.8(3)
N10-Tc-N1 107.0(4)/104.8(4) N10-Tc-P2
Tc-N1-P1 126.5(4)/124.6(4) N1-P1-C10
93.8(3)/96.2(3)
104.9(4)/105.6(4)
the Re-N(imine) bond lengths in 1 and 2 and the Re-N1
bond length in 4, although the latter one belongs to a
phosphoraneiminato unit. However, the values are in the
range of the M-N bond lengths in the other structurally
characterized osmium and rhenium complexes with bridging
phosphoraneiminates.5
Our attempts to isolate crystalline products from reactions
4 4 2 3 2 2
of [NBu ][TcOCl ] with Ph P(NSiMe )CH PPh failed up
to now. Independent of the solvents and the ratios of the
reactants only mixtures of different complexes are formed.
Further ligand exchange and the formation of [TcNCl-
(Ph
2
PCH
2
PPh
2
NH)
2
]Cl (7) is observed when [NBu
4
][TcNCl
4
]
reacts with a large excess of Ph
is indicated by a change of the color of the reaction mixture
from orange-red to yellow-brown. Yellow needles of
2
P(NSiMe )CH PPh
3
2
2
. This
,6
[TcNCl(Ph
2 2
PCH PPh
2
NH)
2 3
]Cl‚2 CH CN precipitate from
such solutions upon standing and cooling overnight. The
ν(TctN) band in this product is observed at 1050 cm ,
-
1
3
1
and the P NMR shows the phosphoraneimine signal as a
doublet at 52.1 ppm and a very broad signal at 37.8 ppm.
The latter one has been assigned to the phosphine site of
the chelating ligand. The broadening of P NMR signals of
phosphorus atoms directly coordinated to technetium in
diamagnetic nitridotechnetium(V) complexes seems to be
typical. It is temperature-dependent and has been attributed
-
The EPR spectroscopic detection of [TcNCl
of 1 equiv of phosphoraneimine confirms the formation of
nitrido species. This technetium(VI) species, however, disap-
4
] after addition
3
1
2 3 2 2
pears after addition of an excess of Ph P(NSiMe )CH PPh ,
and a mixture of various diamagnetic Tc(V) complexes is
formed as can be concluded from the 31P NMR spectra of
the resulting solutions. This led us to study the ligand
exchange reaction starting from [NBu
When [NBu ][TcNCl ] is mixed with equimolar amounts
or a slight excess of Ph P(NSiMe )CH PPh , only an
intermediate color change is observed. But no more EPR
signal can be detected in the finally obtained orange-red
solution. This indicates reduction or dimerization of the
3
1
to a scalar coupling of the P nucleus with the quadrupole
moment of 99Tc in a previous paper.42
4 4
][TcNCl ].
4
4
2 2 2 2
The structure of the [TcNCl(Ph PCH PPh NH)
]+ cation
2
3
2
2
is very similar to that of the corresponding rhenium complex.
The technetium-nitrogen triple bond causes a strong trans-
influence, which results in a very long Tc-Cl bond of
2
.715(1) Å. Delocalization of electron density from the
technetium complex. Orange-red crystals of [TcNCl
PCH PPh NH] (6) deposit upon cooling. The compound is
soluble in organic solvents such as CHCl or acetonitrile and
2 2
(Ph -
PdN bonds to the neighboring P-C bonds is indicated by
two sets of bond lengths of the P-C10 and P-C20 bonds
2
2
3
(1.794(3) and 1.808(3) Å from the P(V) atoms and 1.838(3)
stable in air. Figure 5 is an ellipsoid representation of the
structure of one of two crystallographically independent
molecules of 6 in its unit cell. Selected bond lengths and
angles are summarized in Table 5. The technetium atom is
five-coordinate with the atoms Cl1, Cl2, P2, and N1 as the
basal plane of an irregular square pyramid and the nitrido
and 1.846(3) Å from the P(III) atoms). More bond lengths
and angles are contained in Table 3 and can easily compared
there with the corresponding values in the [ReNCl(Ph PCH -
2 2
(42) Abram, U.; Lorenz, B.; Kaden, L.; Scheller, D. Polyhedron 1988, 7,
285.
Inorganic Chemistry, Vol. 44, No. 9, 2005 3179

Hecht et al.
PPh
2
NH)
2
]+ and [ReN(OSiMe
3
)(Ph
2
PCH
2
PPh
2
NH)
2
]+ cat-
complexes. The stability of the products is increased when
the phosphoraneimine units are constituents of chelating
systems.
Phosphoraneiminato complexes are formed under exclu-
sion of moisture and strict control of the reaction.
ions. The nitrogen atoms of the ligands are linked with the
chloride counterion by hydrogen bonds as is shown in
Figure 6.
Conclusions
Acknowledgment. We thank the Hermann-Starck AG,
Goslar, for providing us with rhenium metal, and Prof. R.
Kirmse, Leipzig, for EPR measurements. S.S.A thanks
CONACYT (Mexico) for financial support.
The examples in the present paper show that common
rhenium and technetium complexes readily react with tri-
methylsilylated phosphoraneimines and that non-nitrido
starting materials are easily converted into nitrido complexes
by cleavage of PdN bonds. Access of moisture or protons
Supporting Information Available: Tables and illustrations
of hydrogen bonds in compounds 1, 2, and 6. This material is
available free of charge via the Internet at http://pubs.acs.org.
from other sources (e.g. decomposition of solvents) results
-
in protonation of {R
3
PdN} units and coordination of the
resulting neutral phosphoraneimines in donor-acceptor
IC048210Q
3180 Inorganic Chemistry, Vol. 44, No. 9, 2005