Reactions of Nitridorhenium(V) and -Osmium(VI) complexes with acylating agents

Article abstract of DOI:10.1021/ic981244b

Interaction of Re(N)L₂ [L ) N(PSPh₂)₂] 1 with (CF₃CO)₂O or RCOCl afforded air-sensitive acylimido-Re(V) complexes trans-Re[NC(O)CF3](OCOCF₃)L₂2 or trans-Re[NC(O)R]ClL₂(R ) CCl₂H 3, CClH₂ 4, CH₃ 5), respectively. Treatment of 1 with (CX3CO)2O followed by recrystallization from CH₂Cl2/hexane in air led to the formation of the corresponding parent imido complexes trans-Re(NH)(OCOCX₃)L₂(X ) F 6, Cl 7). The structure of 7 has been characterized by X-ray crystallography. The Re-N, average Re-S, and Re-O distances are 1.664(3), 2.441, and 2.116(3) ?, respectively. Deprotonation of 6 or 7 with Et3N gave 1. Recrystallization of 3 from CH₂Cl2/ hexane in air resulted in oxo-imido exchange and the isolation of the oxo-Re(V) species trans-Re(O)ClL₂. Treatment of 1 with tosyl anhydride gave trans-Re(NH)(OTs)L₂ (OTs ) tosyl) 8. Reaction of [n-Bu4N][OsNCl4] with KL afforded trans-Os(N)ClL₂ 9, which has been characterized by X-ray crystallography. The Os-N, Os-Cl, and average Os-S bond distances in 9 are 1.64(1), 2.577(4), and 2.429 ?, respectively. Treatment of 10 with (CF₃CO)2O, Ag(CF₃CO₂), or CF₃CO₂H resulted in chloride substitution and the formation of trans-Os(N)- (OCOCF₃)L2 10. The Os-N, Os-O, and average Os-S distances in 10 are 1.643(5), 2.271(4), and 2.419 ?, respectively. Treatment of 1 with [Ph3C]BF4 resulted in the isolation of trans-Re(NCPh₃)(F)L₂ 11, presumably via the cationic tritylimido intermediate [Re(NCPh₃)L₂]+. Reaction of 9 with [Ph3C]BF4 led to chloride abstraction and the formation of five-coordinate [Os(N)L₂]BF4 12. The Os-N and average Os-S distances in 12 are 1.646(5) and 2.364 ?, respectively.

Full text of DOI:10.1021/ic981244b

3000
Inorg. Chem. 1999, 38, 3000-3005
Reactions of Nitridorhenium(V) and -Osmium(VI) Complexes with Acylating Agents
Wa-Hung Leung,*,† Joyce L. C. Chim,† Ian D. Williams,† and Wing-Tak Wong‡
Departments of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,
Kowloon, Hong Kong, and The University of Hong Kong, Pokfulam Road, Hong Kong
ReceiVed October 23, 1998
Interaction of Re(N)L2 [L ) N(PSPh2)2] 1 with (CF3CO)2O or RCOCl afforded air-sensitive acylimido-Re(V)
complexes trans-Re[NC(O)CF3](OCOCF3)L2 2 or trans-Re[NC(O)R]ClL2 (R ) CCl2H 3, CClH2 4, CH3 5),
respectively. Treatment of 1 with (CX3CO)2O followed by recrystallization from CH2Cl2/hexane in air led to the
formation of the corresponding parent imido complexes trans-Re(NH)(OCOCX3)L2 (X ) F 6, Cl 7). The structure
of 7 has been characterized by X-ray crystallography. The Re-N, average Re-S, and Re-O distances are 1.664(3),
2.441, and 2.116(3) Å, respectively. Deprotonation of 6 or 7 with Et3N gave 1. Recrystallization of 3 from CH2Cl2/
hexane in air resulted in oxo-imido exchange and the isolation of the oxo-Re(V) species trans-Re(O)ClL2. Treatment
of 1 with tosyl anhydride gave trans-Re(NH)(OTs)L2 (OTs ) tosyl) 8. Reaction of [n-Bu4N][OsNCl4] with KL
afforded trans-Os(N)ClL2 9, which has been characterized by X-ray crystallography. The Os-N, Os-Cl, and
average Os-S bond distances in 9 are 1.64(1), 2.577(4), and 2.429 Å, respectively. Treatment of 10 with
(CF3CO)2O, Ag(CF3CO2), or CF3CO2H resulted in chloride substitution and the formation of trans-Os(N)-
(OCOCF3)L2 10. The Os-N, Os-O, and average Os-S distances in 10 are 1.643(5), 2.271(4), and 2.419 Å,
respectively. Treatment of 1 with [Ph3C]BF4 resulted in the isolation of trans-Re(NCPh3)(F)L2 11, presumably
via the cationic tritylimido intermediate [Re(NCPh3)L2]+. Reaction of 9 with [Ph3C]BF4 led to chloride abstraction
and the formation of five-coordinate [Os(N)L2]BF4 12. The Os-N and average Os-S distances in 12 are 1.646(5)
and 2.364 Å, respectively.
Introduction
Scheme 1
Acylimido-metal complexes [M ) NC(O)R] have attracted
much attention due to their applications in metal-mediated
nitrogen atom transfer reactions. Groves and co-workers first
reported that trifluoroacetylimido-Mn(V) species, which were
prepared in situ from nitrido-Mn(V) porphyrins and trifluoro-
acetic anhydride, react with olefins to give trifluoroacylaziridines
and Mn(III) porphyrins.1 More recently, this reaction was
applied to organic synthesis by Carreira and co-workers, who
used nitrido-Mn(salen) complexes in conjunction with trifluo-
roacetic anhydride as reagents for amination of electron-rich
olefins including silyl enol ethers and glycals.2 Acetylimido-
Os(VIII) species have also been implicated as the active species
for the Os-mediated aminohydroxylation of olefins.3 Neverthe-
less in contrast to organoimido-metal (MdNR, R ) alkyl or
aryl) complexes, there are very few acylimido-metal complexes
reported in the literature. Isolated acylimido complexes include
Mo[NC(O)Ph](Et2dtc)3 (Et2dtc ) N,N′-diethyldithiocarbamate),4
Tp′WIV(CO)Cl[NC(O)CH3],5 Tp′WIV(CO)(SPh)[NC(O)CH3] (Tp′
) hydridotris(3,5-dimethylpyrazol-1-yl)borate),6 and WVICl2-
[NC6H3(i-Pr)2-2,6][NC(O)C6H4Me-4](OPMe3)(PMe3).7 To un-
derstand the factors governing metal-mediated acylimido trans-
fer, we set out to synthesize acylimido-Re(V) complexes, which
are expected to be more stable than the Mn(V) congeners.
Although nitrido-Re(V) complexes are known to be nucleophilic
and react with electrophiles to give µ-nitrido or imido
complexes,8-10 as far as we are aware, there are no reports on
the reaction of nitrido-Re(V) with acetylating agents. We are
particularly interested in nitrido-Re(V) complex containing bis-
(diphenylthiophosphoryl)amide (L, Scheme 1),10 which has been
reported to form adduct with BCl3. Herein we describe the
* To whom correspondence should be addressed. E-mail: chleung@ust.hk.
† The Hong Kong University of Science and Technology.
‡ The University of Hong Kong.
(1) (a) Groves J. T.; Takahashi, T. J. Am. Chem. Soc. 1983, 105, 2073.
(b) Groves, J. T.; Takahashi, T.; Butler, M. Inorg. Chem. 1983, 22,
884.
(2) Du Bois, J.; Tomooka, C. S.; Hong J.; Carreira, E. M. Acc. Chem.
Res. 1997, 30, 364 and references cited therein.
(3) (a) Li, G.; Angert, H. H.; Sharpless, K. B. Angew. Chem., Int. Ed.
Engl. 1997, 35, 2813. (b) Rudolph, J.; Sennhenn, P. C.; Vlaar C. P.;
Sharpless, K. B. Angew. Chem., Int. Ed. Engl. 1997, 35, 2810.
(4) Bishop, M. W.; Chatt, J.; Dilworth, J. R.; Neaves, B. D. J. Organomet.
Chem. 1981, 213, 109.
(6) Thomas, S.; Lim, P. J.; Gable, R. W.; Young, C. G. Inorg. Chem.
1998, 37, 590.
(7) Nielson, A. J.; Hunt, P. A.; Rickard, C. E. F.; Schwerdtfeger, P. J.
Chem. Soc., Dalton Trans. 1997, 3311.
(8) (a) Kafitz, W.; Weller, F.; Dehnicke, K. Z. Anorg. Allg. Chem. 1982,
490, 175. (b) Beuter, G.; Englert, U.; Strahle, Z. Naturforsch. 1988,
43B, 145. (c) Ritter, S.; Abram, U. Inorg. Chim. Acta 1995, 231, 245.
(d) Ritter, S.; Hu¨bener, R.; Abram, U. J. Chem. Soc., Chem. Commun.
1995, 2047. (e) Doerer, L. H.; Graham, A. J.; Green, M. L. H. J.
Chem. Soc., Dalton Trans. 1998, 3941.
(9) Dehnicke, K.; Strahle, J. Angew. Chem., Int. Ed. Engl. 1992, 31, 955.
(10) Abram, U.; Schulz Lang, E.; Abram, S.; Wegmann, J.; Dilworth, J.
R.; Kirmse R.; Woollins, J. D. J. Chem. Soc., Dalton Trans. 1997,
623.
(5) Pe´rez, P. J.; Luan, L.; White, P. S.; Brookhart, M.; Templeton, J. L.
J. Am. Chem. Soc. 1992, 114, 7928.
10.1021/ic981244b CCC: $18.00 © 1999 American Chemical Society
Published on Web 05/18/1999

Nitridorhenium(V) and -Osmium(VI) Complexes
Inorganic Chemistry, Vol. 38, No. 12, 1999 3001
Et2O in air afforded green crystals, which were collected and washed
with Et2O (yield: 0.1 g, 88%). H NMR (CDCl3): δ 7.30-7.82 (m,
reactions of Re(N)L2 and isoelectronic trans-Os(N)ClL2 with
acylating agents and the characterization of the resulting imido
or nitrido species.
1
phenyl protons). 31P{1H} NMR (CDCl3): δ 44.68 (s). IR (cm-1, KBr):
3045 w [ν(N-H)], 1700 [ν(CdO)]. Anal. Calcd for ReC50H41N3-
Cl3O2P4S4: C, 44.4; H, 2.9; N, 3.0. Found: C, 44.7; H, 3.5; N, 2.0.
Preparation of trans-Re(NH)(OTs)L2 (Ts ) tosyl) 8. To a solution
of 1 (80 mg, 0.07 mmol) in CH2Cl2 (20 mL) was added tosyl anhydride
(24 mg, 0.07 mmol), and the reaction mixture was stirred under nitrogen
at room temperature overnight. The solvent was pumped off and the
residue was washed with Et2O. Recrystallization from CH2Cl2/hexane
in air afforded yellowish green crystals (yield 14 mg, 15%) along with
Experimental Section
General Considerations. NMR spectra were recorded on a Bruker
ALX 300 spectrometer operating at 300, 282.4, and 121.5 MHz for
1H, 19F, and 31P, respectively. Chemical shifts (δ, ppm) were reported
with reference to Si(CH3)4 (1H), CF3C6H5 (δ - 64) (19F), and H3PO4
(31P). Infrared spectra (Nujol) were recorded on a Perkin-Elmer 16 PC
FT-IR spectrophotometer and mass spectra on a Finnigan TSQ 7000
spectrometer. Elemental analyses were performed by Medac Ltd.,
Surrey, UK.
1
unreacted 1. H NMR (CD2Cl2): δ 2.27 (s, 3H, p-Me), 6.82 (d, 2H,
Hm), 7.91 (d, 2H, Ho), 7.23-7.79 (m, 40H, phenyl protons). 31P{1H}
NMR (CD2Cl2): δ 45.04 (s).
Solvents were purified by standard procedures and distilled prior to
use. All manipulations, unless otherwise stated, were carried out under
nitrogen using standard Schlenk techniques. Re(N)L2 110 and [n-Bu4N]-
[OsNCl4]11 were prepared according to the literature methods. KL was
synthesized by deprotonation of HL12 with potassium tert-butoxide in
methanol. (CF3CO)2O, (CCl3CO)2O, (CHCl2CO)Cl, CH2ClCOCl,
CH3COCl, and tosyl anhydride were purchased from Aldrich and used
as received.
Preparation of trans-Os(N)ClL2 9. To a solution of [n-Bu4N]-
[OsNCl4] (0.05 g, 0.09 mmol) in methanol (20 mL) was added KL
(0.11 g, 0.23 mmol), and the mixture was stirred at room temperature
for 2 h. The orange solid was collected, washed with methanol, and
1
recrystallized from CH2Cl2/Et2O (yield 60%). H NMR (CDCl3): δ
7.23-7.83 (m, phenyl protons). 31P{1H} NMR (CDCl3): δ 40.4 (s).
IR (Nujol, cm-1): 1064 [ν(OstN)]. Anal. Calcd for C48H40NClP4S4-
Os: C, 50.7; H, 3.5; N, 3.7. Found: C, 50.6; H; 3.6; N, 3.7.
Preparation of trans-Os(N)(OCOCF3)L2 10. To a solution of 9
(100 mg, 0.09 mmol) in CH2Cl2 (20 mL) was added (CF3CO)2O (0.1
mmol, 1 mL of 1 M solution in CH2Cl2), and the mixture was stirred
at room temperature for 1 h. The solvent was pumped off and the
residue washed with hexane. Recrystallization of the residue from
CH2Cl2/Et2O afforded air-stable orange crystals (yield 78 mg, 70%).
Alternatively 10 could be prepared in similar yield by treatment of 9
with 1 equiv of Ag(CF3CO2) or CH3CO2H. 1H NMR (CD2Cl2): δ 7.24-
7.83 (m, phenyl protons); 19F NMR (CD2Cl2): δ -76.3 (s). 31P{1H}
NMR (CD2Cl2): δ 41.18 (s). IR (cm-1, Nujol): 1696 [ν(CdO)], 1082
[ν(OstN)]. Anal. Calcd for C50H41N3ClF3O2P4S4Os: C, 48.0; H, 3.3;
N, 3.4. Found: C, 48.4; H, 3.4; N, 3.3.
Preparation of trans-Re(NCOCF3)(OCOCF3)L2 2. To a solution
of 1 (80 mg, 0.07 mmol) in CH2Cl2 (15 mL) at -10 °C was added
(CF3CO)2O (0.1 mmol, 0.1 mL of a 1 M solution in CH2Cl2) under
nitrogen. The reaction mixture was warmed to room temperature and
stirred for 30 min. Concentration (to ca. 5 mL) and addition of hexane
1
resulted in the formation of an orange solid (yield 70 mg, 79%). H
NMR (CDCl3): δ 7.30-7.77 (m, phenyl protons). 19F NMR (CDCl3):
δ -72.3 (s, NCOCF3), -76.8 (OCOCF3). 31P{1H} NMR (CDCl3): δ
51.2 (s). IR (cm-1, Nujol): 1698, 1710 [ν(CdO)], 1050 sh ([ν(RedN)].
Anal. Calcd for C52H40N3F6O3P4S4Re: C, 47.8; H, 3.1; N, 3.2. Found:
C, 47.7; H, 3.2; N, 3.4.
Preparation of trans-Re(NCOCHCl2)(Cl)L2 3. To a solution of 1
(100 mg, 0.1 mmol) in CH2Cl2 (10 mL) at 0 °C was added 1 equiv of
CHCl2COCl, and the mixture was slowly warmed to room temperature
and stirred for 30 min. Addition of hexane (40 mL) afforded an orange
solid, which was collected and washed with hexane (yield 90 mg, 80%).
1H NMR (CDCl3): δ 7.30-7.77 (m, phenyl protons). 31P{1H} NMR
(CDCl3): δ 51.23 (s). IR (cm-1, Nujol): 1716 [ν(CdO)]. MS (FAB):
m/z 1208 (M+ - Cl). Anal. Calcd for C50H41Cl3N3OP4S4Re‚CH2Cl2:
C, 46.1; H, 3.2; N, 3.2. Found: C, 46.3; H, 3.2, H, 3.1.
Reaction of 1 with CClH2COCl. To a solution of 1 (20 mg) in
CDCl3 (0.5 mL) at 0 °C was added CClH2COCl (0.05 mL), and the
resulting red mixture was warmed to room temperature and analyzed
by NMR spectroscopy. 1H NMR (CDCl3): δ 3.04 (s, 2H, CClH2CO),
7.19-7.85 (m, 40H, phenyl protons). 31P{1H} NMR (CDCl3): δ 48.52
(s).
Preparation of trans-Re(NCPh3)(F)L2 11. To a solution of 1 (80
mg, 0.07 mmol) in CH2Cl2 (20 mL) at 0 °C was added 1 equiv of
[Ph3C](BF4) (24 mg, 0.07 mmol), and the reaction mixture was stirred
at room temperature overnight. The solvent was pumped off and the
residue was extracted with Et2O. Recrystallization from Et2O/hexane
1
afforded pale purple crystals (yield 50 mg, 53%). H NMR (CDCl3):
δ 6.69-7.90 (m, phenyl protons). 31P{1H} NMR (CDCl3): δ 40.61
(s). 19F NMR (CDCl3): δ -86 (s). IR (cm-1, Nujol): 1192 sh
[ν(RedN)]. FAB MS: 1359 (M + 1)+. Anal. Calcd for ReC67H55-
FN3P4S4: C, 59.2; H, 4.1; N, 3.1. Found: C, 58.4; H, 4.3; N, 2.9.
Preparation of [Os(N)L2](BF4) 12. To a solution of 9 (100 mg,
0.09 mmol) in CH2Cl2 (20 mL) was added 1 drop of HBF4 (1M in
Et2O). After stirring at room temperature for 1 h, the solvent was
pumped off and the residue washed with Et2O. Recrystallization from
CH2Cl2/hexane afforded yellow crystals, which are suitable for X-ray
diffraction study (yield 73 mg, 70%). Alternatively 11 could be isolated
in similar yield by treatment of 9 with [Ph3C](BF4). 1H NMR
(CDCl3): δ 7.34-7.84 (m, phenyl protons); 31P{1H} NMR (CDCl3):
δ 36.41 (s). MS (FAB): m/z 1102 (M+ - BF4). Anal. Calcd. for C48H40-
BF4N3OsP4S4: C, 45.0; H, 3.3; N, 3.2. Found: C, 44.5; H, 3.1; N,
3.0%.
Reaction of 1 with CH3COCl. This was done as for CClH2COCl
using CH3COCl (0.05 mL) in place of CH2ClCOCl. The resulting red
solution mixture was analyzed by NMR spectroscopy. 1H NMR
(CDCl3): δ 2.08 (CH3CO), 7.19-7.85 (m, 40H, phenyl). 31P{1H} NMR
(CDCl3): δ 56.25 (s).
Preparation of trans-Re(NH)(OCOCF3)L2 6. A solution of 2 (100
mg, 0.08 mmol) in CH2Cl2/Et2O was left to stand in air overnight. The
green crystals formed were collected and washed with Et2O (yield 100
mg, 88%). Alternatively, 6 was obtained in good yield by treatment of
1 in CH2Cl2 with (CF3CO)2O, followed by recrystallization from
X-ray Crystallography. A summary of pertinent crystallographic
data and experimental details for complexes 7‚CH2Cl2, 9‚CH2Cl2,
10‚2CH2Cl2‚C6H14, and 12‚1.5CH2Cl2 are listed in Table 1. Data were
collected on a MAR-Research image-plate diffractometer (for 7‚
CH2Cl2), Rigaku AFC7R diffractometer (for 9‚CH2Cl2), and Siemens
P4 dffractometer (for 10‚2CH2Cl2‚C6H14 and 12‚1.5CH2Cl2) using
graphite-monochromated radiation (λ ) 7.0073 Å). All intensities were
corrected for Lorentz and polarization effects. An approximation to
absorption correction was also applied. The structures were solved by
direct methods and refined by full matrix least-squares analysis. Non-
hydrogen atoms for 7•CH2Cl2 and 10‚2CH2Cl2‚C6H14 were refined
anisotropically while those for 12‚1.5CH2Cl2 were refined isotropically.
For 9, the Os, Cl, P, and S atoms were refined anisotropically while
the remaining non-hydrogen atoms were refined isotropically. For
7•CH2Cl2, the hydrogen atom on imido group was located by difference
Fourier synthesis based on low angle data (θ < 15°) while hydrogen
1
CH2Cl2/hexane in air for 1 d. H NMR (CDCl3): δ 7.34-7.85 (m,
phenyl protons). 19F NMR (CDCl3): δ -76.8 (s, CO2CF3). 31P{1H}
NMR (CDCl3): δ 44.8 (s). IR (cm-1, Nujol): 3045 w br [ν(N-H)],
1708 [ν(CdO)], 1073 sh [ν(RedN)]. Anal. Calcd for C50H41N3F3O2P4S4-
Re‚CH2Cl2: C, 47.2; H, 3.3; N, 3.2. Found: C, 47.9; H, 3.3; N, 3.5.
Preparation of trans-Re(NH)(OCOCCl3)L2 7. To a solution of 1
(80 mg, 0.07 mmol) was added (CCl3CO)2O (0.1 mol), and the mixture
was stirred at room temperature for 1 h. The solvent was pumped off
and the residue washed with hexane. Recrystallization from CH2Cl2/
(11) Griffith, W. P.; Paulson, D. J. Chem. Soc., Dalton Trans. 1973, 1315.
(12) Wang, F. T.; Najdzionek, J.; Leneker, K. L.; Wasserman, H.; Braitsch,
D. M. Metal-Org. Chem. 1978, 8, 120.

3002 Inorganic Chemistry, Vol. 38, No. 12, 1999
Leung et al.
Table 1. Crystal Data and Experimental Details for trans-Re(NH)L2(CCl3CO2)‚CH2Cl2 (7‚CH2Cl2), trans-Os(N)ClL2‚CH2Cl2 (9‚CH2Cl2),
trans-Os(N)(OCOCF3)L2‚C6H14‚2CH2Cl2 (10‚C6H14‚2CH2Cl2), and trans-[Os(N)L2]BF4‚1.5CH2Cl2 (12‚1.5CH2Cl2)
7‚CH2Cl2‘
9‚CH2Cl2
10‚C6H14‚2CH2Cl2
12‚1.5CH2Cl2
empirical formula
formula weight
crystal system
a, Å
b, Å
c, Å
C51H43N3Cl5O2P4S4Re
1345.53
monoclinic
14.009(1)
16.850(1)
25.528(2)
C49H42NCl3P4S4Os
1221.59
triclinic
11.475(1)
17.493(2)
25.697(4)
86.12(2)
84.83(2)
86.85(2)
5119(1)
P1h (no. 2)
4
C58H58Cl4F3N3O2P4S4Os
1470.2
triclinic
C49.5H40BCl3F4N3P4S4Os
1312.3
monoclinic
13.464(2)
24.618(2)
17.083(2)
12.967(4)
15.943(5)
16.468(5)
80.70(2)
72.67(3)
70./27(2)
3052.2(16)
P1h (no. 2)
2
R, deg
â, deg
99.43(2)
95.72(2)
g, deg
V, Å3
5478.8(7)
P21/c (no. 14)
4
1.631
25
2680
27.75
5714.9(12)
Cc
4
1.525
25
2600
26.78
space group
Z
F
calcd, g cm-3
temperature, °C
F(000)
1.585
25
2432
29.71
1.600
-70
1476
µ(Mo KR), cm-1
no. of observation
no. of variables
weighing factor
R, %
25.6
7758 (I > 3.0σ(I))
8074 (I > 3.0σ(I))
7832 (F > 4.0σ(F))
7375 (F > 4.0σ(F))
631
633
680
629
1/[σ2(Fo) + 0.023Fo /4]
1/σ2(Fo)
4.6
1/[σ2(Fo) + 0.0003Fo ]
1/[σ2(Fo) + 0.0003Fo ]
2
2
2
3.2
4.44
4.74
1.30
3.87
4.28
1.32
Rw, %
goodness of fit
3.7
1.58
4.6
2.11
2
1/2
a R ) (∑|Fo| - |Fc|)/∑|Fo|. b Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2
.
c Goodness of fit ) [(∑w|Fo| - |Fc|)2/∑Nobs - Nparam
] .
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
trans-Re(NH)(OCOCCl3)L2‚CH2Cl2 (7‚CH2Cl2)
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
trans-Os(N)(OCOCF3)L2‚CH2Cl2‚C6H14 (10‚CH2Cl2‚C6H14)
Bond Lengths
Re(1)-S(1)
Re(1)-S(3)
Re(1)-O(1)
S(1)-P(1)
S(3)-P(3)
P(1)-N(1)
P(3)-N(2)
2.472(1)
2.480(1)
2.116(3)
2.043(2)
2.071(2)
1.600(3)
1.588(4)
Re-S(2)
2.398(1)
2.412(1)
1.664(3)
2.058(2)
2.053(2)
1.591(4)
1.577(3)
Os-S(1)
Os-S(3)
Os-O(1)
2.443(2)
2.403(2)
1.643(5)
Re(1)-S(4)
Re(1)-N(1)
S(2)-P(2)
S(4)-P(4)
P(2)-N(1)
P(4)-N(2)
S(1)-Os-S(2)
S(1)-Os-S(4)
S(1)-Os-N(2)
S(2)-Os-S(4)
S(2)-Os-N(2)
S(3)-Os-O(1)
S(4)-Os-O(1)
O(1)-Os-N(2)
163.9(1)
80.9(1)
85.0(1)
81.2(2)
97.3(1)
97.0(2)
100.0(2)
Bond Angles
S(1)-Re(1)-S(2)
S(1)-Re(1)-S(4)
S(1)-Re(1)-N(3)
S(2)-Re(1)-S(4)
S(2)-Re(1)-N(3)
S(3)-Re(1)-O(1
S(4)-Re(1)-O(1)
O(1)-Re(1)-N(3)
97.67(3)
171.60(4)
92.1(1)
77.16(4)
102.63(9)
77.60(7)
87.17(8)
173.1(1)
S(1)-Re(1)-S(3)
S(1)-Re(1)-O(1)
S(2)-Re(1)-S(3)
S(2)-Re(1)-O(1)
S(3)-Re(1)-S(4)
S(3)-Re(1)-N(3)
S(4)-Re(1)-N(3)
84.17(4)
85.71(8)
161.49(4)
84.15(7)
98.64(4)
95.69(9)
95.5(1)
Os-S(4)
Os-S(3)
Os-N(3)
2.357(5)
2.401(4)
1.646(5)
Os-S(2)
2.373(4)
2.325(4)
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
trans-Os(N)ClL2‚CH2Cl2 (9‚CH2Cl2)
Os-S(1)
Bond Lengths
Bond Angles
Os(1)-Cl(2)
Os(1)-S(2)
Os(1)-S(4)
2.577(4)
2.454(4)
2.399(3)
Os(1)-S(1)
Os(1)-S(3)
Os(1)-N(3)
2.417(4)
2.444(4)
1.64(1)
S(4)-Os-S(3)
S(4)-Os-S(1)
S(3)-Os-S(2)
S(3)-Os-N(3)
S(2)-Os-N(3)
94.9(1)
141.2(2)
154.9(2)
102.6(6)
102.5(6)
S(4)-Os-S(2)
S(4)-Os-N(3)
S(3)-Os-S(1)
S(2)-Os-S(1)
S(1)-Os-N(3)
75.5(2)
110.0(6)
76.8(1)
96.0(1)
108.8(6)
Bond Angles
Cl(2)-Os(1)-S(1)
Cl(2)-Os(1)-S(3)
Cl(2)-Os(1)-N(3)
S(1)-Os(1)-S(3)
S(1)-Os(1)-N(3)
S(2)-Os(1)-S(4)
S(3)-Os(1)-S(4)
S(4)-Os(1)-N(3)
87.3(1)
79.3(1)
172.6(4)
165.6(1)
97.4(4)
167.0(1)
96.5(1)
97.4(4)
Cl(2)-Os(1)-S(2)
Cl(2)-Os(1)-S(4)
S(1)-Os(1)-S(2)
S(1)-Os(1)-S(4)
S(2)-Os(1)-S(3)
S(2)-Os(1)-N(3)
S(3)-Os(1)-N(3)
Os(1)-S(1)-P(1)
80.3(1)
87.3(1)
98.1(1)
77.5(1)
84.9(1)
93.4(4)
96.5(4)
109.9(2)
solution, from which the trifluoroacetylimido-Re(V) species
trans-Re[NC(O)CX3](OCOCX3)L2 2 was isolated as an analyti-
cally pure solid (eq 1).
atoms on the organic moieties were generated in their idealized positions
(C-H, 0.95 Å). In the crystal structure of 12‚1.5CH2Cl2, the BF4
counteranion is disordered. Two CH2Cl2 molecules were found in partial
occupancy and were refined as 75%. Selected bond lengths and angles
for 7, 9, 10 and 12 are listed in Tables 2, 3, 4, and 5, respectively.
The course of reaction has been monitored by 31P and 19F
NMR spectroscopy. Upon addition of 1 equiv of (CF3CO)2O
to 1 in CDCl3, the signals for (CF3CO)2O (δF -75.5) and 1 (δP
38.0) disappeared and a new species 2 (δF -72.3-76.8; δP 51.2)
Results
Acylimido Complexes of Re(V). Treatment of yellow 1 in
CH2Cl2 with a slight excess of (CF3CO)2O gave an orange

Nitridorhenium(V) and -Osmium(VI) Complexes
Inorganic Chemistry, Vol. 38, No. 12, 1999 3003
was formed. Complex 2 is stable in the solid state but
decomposes readily in solution to give a green species, identified
as a Re(V) parent imido species (see below). However, in the
presence of excess (CF3CO)2O, 2 is stable in solution for hours.
The IR spectrum of 2 shows two CdO bands at 1698 and 1710
cm-1, assignable to acyl and acetate groups. Unlike acylimido-
Mn(V) complexes, no reactions of 2 with olefins (e.g., styrene)
or silyl enol ethers (e.g., 2-methyl-1-(trimethylsilyloxyl)-1-
propene) were observed.
Alternatively, acylimido-Re(V) complexes can be prepared
by reaction of nitrido-Re(V) with acyl chlorides. Thus, treatment
of 1 with CCl2HCOCl in CH2Cl2 afforded trans-Re[NC(O)-
CCl2H]ClL2 3, isolated as an orange solid. Complex 3 is air
stable in the solid state but is somewhat moisture sensitive in
solutions. However, unlike 2, hydrolysis of 3 yielded the known
oxo-Re(V) species trans-Re(O)ClL2,13 which was identified by
IR spectroscopy and elemental analysis, instead of the parent
imido species. The oxo-Re(V) species is apparently formed via
oxo-imido exchange of 3 because the organic product CCl2-
HC(O)NH2 has been identified by NMR and IR spectroscopy
(eq 2).
Figure 1. Perspective view of trans-Re(NH)(CCl3CO2)L2 (7).
than that for 1 (1.647(7) Å)10 but is shorter than that for ReCl2-
(NH)(NHNH2)(PPh3)2 (1.712(8) Å).14 Nevertheless, the Re-N
distance in ReCl2(NH)(NHNH2)(PPh3)2 is long apparently due
to strong trans influence of the hydrazido ligand. It might be
noted that the Re-N distance in 7 is closer to that in the BCl3
adduct Re(NBCl3)L2 (1.672(3) Å)10 than to those typical for
organoimido-Re(V) complexes, e.g., Re(NPh)Cl3(PPh3)2 (1.726(6)
Å),15 which contain nitrogen-carbon covalent bonds. This
Re-N bond distance may suggest the resonance structure
RetNδ--Hδ+ for 7. In other words, the imido nitrogen in 7
has a strong nitride character. The imido hydrogen was located
by difference Fourier synthesis, and the N-H distance and Re-
N-H angle for 7 are estimated to be 1.0 Å and 103.1°,
respectively. The formulation of 7 as a nitrido-Re(V) complex
of protonated L is ruled out because the PdS and P-N distances
in 7 are very similar to those found in Re(NBCl3)L2, which
contains deprotonated L.10 Moreover a single 31P resonant signal
was observed for 7 at temperatures down to -50 °C, suggesting
that all the PdS bonds should be equivalent. Despite numerous
attempts, we were not able to observe the imido hydrogen of 7
The ν(CdO) for 3 of 1716 cm-1 is higher than those for 2.
Similarly, treatment of 1 with RCOCl gave the respective
acylimido species Re[NC(O)R]ClL2 (R ) CH2Cl 4, CH3 5),
which hydrolyze readily to give trans-Re(O)ClL2.
Parent Imido Complex of Re(V). Attempts to recrystallize
2 from CH2Cl2/Et2O led to isolation of the green parent imido-
Re(V) complex trans-Re(NH)(OCOCF3)L2 6, which could also
be synthesized directly by the reaction of 1 with (CF3CO)2O
followed by recrystallization in air. Similarly, treatment of 1
with (CCl3CO)2O followed by recrystallization from CH2Cl2/
hexane in air afforded the trichloroacetate compound trans-
Re(NH)(OCOCCl3)L2 7. Apparently, these parent imido-Re(V)
complexes were formed by hydrolysis of the acylimido-Re(V)
species by the trace amount of water in solvent because addition
of water to 2 in CDCl3 at -40 °C gave 6 immediately (eq 3).
1
by H NMR spectroscopy probably due to protic character of
imido hydrogen. Previously it was reported that the NH proton
signal for Mo(NH)(OTf)(syn-Me8[16]aneS4)}OTf (Me8[16]-
aneS4 ) 3,3,7,7,11,11,15,15-octamethyl-1,5,9,13-tetrathiacyclo-
hexadecane, OTf ) triflate) occurs at δ 7.49.16 Therefore it is
possible that the NH signal for 7 may also lie in this region,
which happens to overlap with the phenyl proton signals of L.
The IR (KBr) spectrum of 7 shows a weak peak at 3045 cm-1
,
which may be tentatively assigned as ν(N-H). This stretching
frequency is lower than those found for Mo(NH)(OTf)(syn-
Me8[16]aneS4)}OTf (3100 cm-1 16
)
and ReCl2(NH)(NHNH2)-
(PPh3)2 (3125 and 3330 cm-1 14
) probably due to protic character
of imido hydrogen. As expected, 6 and 7 are acidic and can be
depronotated by bases such as Et3N to give 1. It may be noted
that acid-base chemistry of parent imido complexes of Mo17
and Re18 is well documented.
In an attempt to synthesize tosylimido-Re(V) complexes,
reaction of tosyl anhydride with 1 was studied. Treatment of 1
The IR spectrum of 6 shows the CO band at 1708 cm-1
assignable to the acetate ligand. The IR CO bands for 2 at 1698
and 1710 cm-1 are therefore assigned to the acyl and acetate
groups, respectively.
The solid-state structure of 7 has been established by X-ray
crystallography. Figure 1 shows a perspective view of 7; selected
bond lengths and angles are listed in Table 2. To our knowledge,
7 is the second structurally characterized parent imido-Re
complex; the first example being ReCl2(NH)(NHNH2)(PPh3)2.14
The Re-N distance in 7 of 1.664(3) Å is only slightly longer
,
(15) Forsellini, E.; Casellato, U.; Grazinani, R.; M. C. Carletti M. C.;
Magon, L. Acta Crystallogr., Sect. C 1984, 40, 1795.
(16) Yoshida, T.; Adachi, T.; Yabunouchi, N.; Ueda, T.; Okamoto, S. J.
Chem. Soc., Chem. Commun. 1994, 151.
(17) (a) Henderson, R. A.; Davies, G.; Dilworth, J. R.; Thornelely, R. N.
F. J. Chem. Soc., Dalton Trans. 1981, 40. (b) Henderson, R. A. J.
Chem. Soc., Dalton Trans. 1983, 51. (c) Pe´rez, P. J.; Luan, L.; White,
P. S.; Brookhart, M.; Templeton, J. L. J. Am. Chem. Soc. 1992, 114,
7928.
(13) Rossi, R.; Marchi, A.; Marvelli, L.; Peruzzini, M.; Castellato, U.;
Graziani, R. J. Chem. Soc., Dalton Trans. 1993, 723.
(14) Dilworth, J. R.; Lewis, J. S.; Miller, J.; Zheng, Y. J. Chem. Soc., Dalton
Trans., 1995, 1357.
(18) Vining, W. J.; Neyhart, G. N.; Nielsen, S.; Sullivan, B. P. Inorg. Chem.
1993, 32, 4214.

3004 Inorganic Chemistry, Vol. 38, No. 12, 1999
Leung et al.
Figure 2. Perspective view of trans-Os(N)ClL2 (9).
with tosyl anhydride for 2 days gave a yellow solution, from
which trans-Re(NH)L2(OTs) 8 was obtained in low yield, along
with the unreacted 1. The parent imido complex 8 was
apparently formed from hydrolysis of the unisolated tosylimido
intermediate trans-Re(NTs)(OTs)L2. The reaction of 1 with tosyl
anhydride is slower than that with (CF3CO)2O possibly because
tosyl is a worse leaving group than CF3CO2.
Figure 3. Perspective view of trans-Os(N)(OCOCF3)L2 (10).
Os-N and average Os-S distances (1.643(5) and 2.421 Å,
respectively) are similar to those for 9. The Os-O distance of
2.271(4) Å is longer than those in K[OsO2(O2CCH3)3] (average
2.026 and 2.148 Å for mono- and bidentate acetates, respec-
tively)21 due to trans influence of nitride.
Acylation of Nitrido-Os(VI).To compare the nucleophilicity
of nitrido-Re(V) with the isoelectronic nitrido-Os(VI) analogue,
the nitrido-Os (VI) complex of L was synthesized. Treatment
of [n-Bu4N][OsNCl4] with 2 equiv of KL afforded trans-[Os(N)-
ClL2] 9, isolated as air-stable orange crystals. The structure of
9 has been confirmed by X-ray crystallography. Figure 2 shows
a diagram of the molecule; selected bond lengths and angles
are given in Table 3. The Os-N and average Os-S distances
in 9 are 1.64(1) and 2.428 Å, respectively. The Os-N distance
for 9 is similar to that in [OsN(mnt)2]- (Os-N ) 1.639(8) Å,
mnt ) maleonitriledithiolate).19 The Os-Cl distance in 9 of
2.577(4) Å is longer than that in trans-[Os(tpy)(N)Cl2]+ [Os-
Cl (trans to Cl) ) 2.346 Å, tpy ) 2,2′:6′,2′′-terpyridine]20 due
to strong trans influence of the nitride. The chloride in 9 is
therefore expected to be substitutionally labile (see below). The
Os is situated at ca. 0.286 Å above mean S4 plane, which is
less than that for 5-coordinate 1 (0.55 Å).10
Treatment of 9 with (CF3CO)2O resulted in color change from
orange to yellow, from which a yellow solid 10 was isolated.
The 19F and 31P NMR spectroscopy shows that 9 (δP 40.4) reacts
cleanly with (CF3CO)2O (δF -75.5) to give 10 (δP 36.5, δF
-76.3). Furthermore, the IR spectrum of 10 shows ν(CdO) at
1696 cm-1, indicative of the presence of trifluoroacetate.
Complex 10 was unambiguously identified as a nitrido-
(trifluoroacetato)-Os(VI) complex, trans-Os(N)(OCOCF3)L2, by
X-ray diffraction study. (CF3CO)2O abstracts chloride instead
of attacking the nitride of 9 (eq 4) apparently because the OstN
is not sufficiently basic and the chloride is labile.
Alkylation of Nitrido-Re(V) and -Os(VI). Treatment of 1
with [Ph3C](BF4) led to isolation of the tritylimido complex
trans-Re(NCPh3)(F)L2 11. The presence of fluoride in 11 is
confirmed by mass spectrometry and 19F NMR spectroscopy
(δF -86). It seems likely that alkylation of 1 initially gave the
cationic 16e tritylimido intermediate trans-[Re(NCPh3)L2]+,
which abstracts fluoride from BF4 to give 11 (eq 5).
On the other hand, treatment of 9 with [Ph3C](BF4) afforded
the cationic nitrido-Os(VI) complex [Os(N)L2]BF4 12, instead
of the Os(VI) tritylimido species. Therefore, like (CF3CO)2O,
the trityl ion abstracts chloride instead of alkylating the nitride
of 9 (eq 6).
Alternatively, complex 12 could be synthesized by reaction
of 9 with HBF4 or AgBF4, with elimination of HCl and AgCl,
respectively. The identity of 12 has been unambiguously
established by X-ray crystallography. To our knowledge com-
plex 12 is the first example of cationic 5-coordinate nitrido-
Os(VI) complex. It may be noted that cationic nitrido-Os(VI)
complexes are usually octahedral. Figure 4 shows a perspective
view of 12; selected bond lengths and angles are listed in Table
5. Complex 12 is isostructural with 110 and has a square
pyramidal geometry. The Os-N and average Os-S distances
are 1.646 and 2.364 Å, respectively. It appears that the Os-N
distance is not very sensitive to the overall charge of the nitrido-
Os complexes as the Os-N distances in cationic 12 and neutral
9 and 10 are all very similar. By contrast, the Os-S distances
in cationic 12 are significantly shorter than those in 9 and 10.
The organic product CF3COCl of the reaction was not
characterized. Consistent with the lability of chloride, 10 was
obtained in good yield from the reaction of 9 with Ag(CF3CO2)
or CF3CO2H. The molecular structure of 10 is shown in Figure
3; selected bond lengths and angles are listed in Table 4. The
(19) Leung, W.-H.; Wu, M.-C.; Che, C.-M.; Wong, W.-T.; Chin, K.-F. J.
Chem. Soc., Dalton Trans. 1994, 2519.
(20) Pipes, D. W.; Bakir, M.; Vitols, S. E.; Hodgson, D. J.; Meyer, T. J. J.
Am. Chem. Soc. 1990, 112, 5507.
(21) Behling, T.; Caparaelli, M. V.; Skapski, A. C.; Wilkinson, G. W.
Polyhedron 1982, 1, 840.

Nitridorhenium(V) and -Osmium(VI) Complexes
Inorganic Chemistry, Vol. 38, No. 12, 1999 3005
complexes may be explained in terms of the relative MdN bond
strength. The RedN multiple bond is strong and therefore imido
N-C(O)R bond cleavage to give stable RedNH species is
preferred to imido group transfer. Furthermore the Mn(V/III)
reduction accompanied by imido group transfer is thermody-
namically more feasible than the Re(V/III) counterpart.
Acylation of Nitrido-Os(VI). Attempts to acylate or alkylate
the nitrido-Os(VI) complex 9 led to chloride abstraction rather
than electrophilic attack on nitride, indicating that nitrido-Os(VI)
is less nucleophilic than the isoelectronic nitrido-Re(V) ana-
logue. As a matter of fact, some nitrido-Os(VI) complexes,
notably trans-[Os(tpy)(N)Cl2]+, exhibit electrophilic character
and react with nucleophiles such as PPh3,26 N3-, and S8.27,28
The low nucleophilicity of nitrido-Os(VI) complexes is at-
tributed to the strong covalent character of OstN bond.
Alkylation of nitrido-Os(VI) to give imido species has only been
observed for [Os(N)R4]- (R ) alkyl)29 and [OsN(bdt)2]- (bdt
) 1,2-benzenedithiolate),30 which contain strongly electron-
releasing alkyl and thiolate ligands, respectively. The micro-
scopic reverse of nitride alkylation, i.e., imido C-N bond
cleavage, is, however, well precedented for imido-Os com-
plexes.23,24
Figure 4. Perspective view of the cation [Os(N)L2]+.
Discussion
Acylation of Nitrido-Re(V). It is well documented that
nitrido-Re(V) complexes are nucleophilic and react with elec-
trophiles to give Re(V) organoimido complexes or adducts of
Re(V) nitride. In this work, we found that acylimido-Re(V)
species can be obtained by acylation of 1 with (RCO2)2O or
RCOCl. In contrast to acetylimido-W complexes,5,6 these
acylimido-Re(V) species are moisture sensitive and undergo
hydrolysis in solution readily. Interestingly, the product of
hydrolysis of RedNC(O)R was found to be dependent on the
substituent R. For highly electron-withdrawing R such as CF3
and CCl3, hydrolysis of RedNC(O)R led to C-N bond cleavage
and the formation of RedNH species. Apparently, the CF3 and
CCl3 groups render the carbonyl very electrophilic and suscep-
tible to nucleophilic attack by water. A similar finding has been
observed for hydrolysis of organic amides: acid hydrolysis of
trihaloacetamide is more facile than that for acetamide.22 By
contrast, for less electron-withdrawing R such as CHCl2, CH2Cl,
and CH3, hydrolysis of RedNC(O)R yielded RedO species via
oxo-imido exchange. It may be noted that while oxo-imido
exchange is well documented for organoimido complexes of
earlier transition metals, which are therefore moisture sensitive,
C-N bond cleavage for imide ligands is less common and has
been observed for organoimido complexes of some later
transition metals, e.g., Os,23,24 Ru,24 and Mo.25
It is also of interest to compare the stability of cationic
5-coordinate [Os(N)L2]+ and [Re(NCPh3)L2]+. While the former
complex is stable for isolation, the latter is believed to be very
-
electrophilic and capable of abstracting fluoride from BF4 . This
indicates that nitride can stabilize the 16e configuration of
Os(VI) by formation of strong OstN triple bond. On the other
hand, the RedNCPh3 bond is comparatively weaker and thus
the imido-Re(V) complex tends to be octahedral in order to fully
utilize the metal d orbitals.
In summary, we have demonstrated that treatment of nitrido-
Re(V) with acylating agents affords acylimido-Re(V) species.
These acylimido-Re(V) complexes undergo hydrolysis to give
parent imido- or oxo-Re(V) species. On the other hand, the
nitrido-Os(VI) analogue is not acylated by trifluoroacetic
anhydride because of its low nucleophilicity.
Acknowledgment. Support from The Hong Kong University
of Science and Technology and The Hong Kong Research
Grants Council is gratefully acknowledged.
Supporting Information Available: X-ray crystallographic files
in CIF format for complexes 7‚CH2Cl2, 9‚CH2Cl2, 10-C6H14‚CH2Cl2,
and 12‚1.5CH2Cl2, are available via the Internet at http://pubs.acs.org.
Unlike acylimido-Mn(V) complexes, complex 2 does not
undergo imido group transfer with olefins and silyl enol ethers.
The difference in reactivity between Mn- and Re-acylimido
IC981244B
(22) Goody, R. S.; Walker, R. T. Tetrahedron Lett. 1967, 289. (b) Greene,
T. W.; Wuts, P. G. M. ProtectiVe Groups in Organic Synthesis, 2nd
ed.; Wiley: New York, 1991; p 349.
(23) (a) Clifford A. F.; Kobayashi, C. S. Inorg. Synth. 1960, 6, 204. (b)
Barner, C. J.; Collins, T. J.; Mapes, B. E.; Santarsiero, B. D. Inorg.
Chem. 1986, 25, 4323.
(24) Leung, W.-H.; Wilkinson, G.; Hussain-Bates, B.; Hursthouse, M. B.
J. Chem. Soc., Dalton Trans. 1991, 2791.
(25) Du, Y.; Rheingold A. L.; Maatta, E. A. J. Chem. Soc., Chem. Commun.
1994, 2163.
(26) (a) Bakir, M.; White, P. S.; Dovletoglou, A.; Meyer, T. J. Inorg. Chem.
1991, 30, 2835.
(27) (a) Demadis, K. D.; El-Samanody, E.-S.; Meyer, T. J.; White, P. S.
Inorg. Chem. 1998, 37, 838. (b) Demadis, K. D.; Meyer, T. J.; White,
P. S. Inorg. Chem. 1998, 37, 3610.
(28) Crevier, T. J.; Lovell, S.; Mayer, J. M.; Rheingold, A. L.; Guzei, I.
A. J. Am. Chem. Soc. 1998, 120, 6607.
(29) Marshman, R. W.; Shapley, P. A. J. Am. Chem. Soc. 1990, 112, 8369.
(30) Sellmann, D.; Wemple, M. W.; Donaubauer, W.; Heinemann, F. W.
Inorg. Chem. 1997, 36, 1397.