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Synthetic Approaches to η1-iminoacylcobalt carbonyl complexes
c5 Journal of Organometallic Chemistry, 169 (1979) C5-C8 o Ekevier Sequoia S.A., Lausanne- Printed in The Netherlands
Preliminary
communication
SYNTHETIC APPROACHES COMPLEXES
TO q l-IMINOACYLCOBALT
CARBONYL
HOWARD ALPER* and MASATO TANAKA Department
oi Chemzktry, University of Ottawa, Ottawa, Ontario, KlN 9B4 (Canada)
(Received January 9th, 1979)
§ummary
Reaction of imidoyl chlorides with triphenylphosphinecobalt tricarbonyl anion or wïth cobalt tetracarbonyl anion in the presence of triphenylphosphine affords Q’-iminoacylcobalt carbonyl complexes in 19-85% yields.
Several recent publications have descrïbed the reactions of imidoyl chlorides wîth metal carbonyl anions. While cyclopentadienyltungsten tricarbonyl anion and the iron dicarbonyl anions form 72’ -iminoacyl complexes on reaction with imidoyl chlorides, the cyclopentadienylmolybdenum tricarbonyl anion bas been reported ta react wïth PhC(Cl)=NPh and PhC(Cl)=NCII, to give, respectively, $-iminoacyl complexes [l] and a complex derived from two imidoyl and one anion units [Z]. Other examples of q*-iminoacylmetal carbonyl complexes have been described very recently [ 3,4] _ Adams and coworkers [l] found that imidoyl chloride-metal carbonyl anion reactions were generally rapid (complete in 30 minutes or less). However, the cobalt tetracarbonyl anion-imidoyl chloride reaction proved to be exceptionally slow, requiring approximately two days for completion, and affording a binuclear cobalt complex (1) containing coupled imidoyl fragments. No l/l mononuclear complex was -formed. This communication describes the first examples of g1 -iminoacylcobalt complexes, prepared by two simple, mild, and convenient methods. Treatment of a series of imidoyl chlorides (II) with triphenylphosphinecobalt tricarbonyl anion (generated by sodium amalgam reduction of bis(triphenylphosphine)dicobalt hexacarbonyl) in rigorously dry tetrahydrofuran (THF) at 0°C (method A), affords the v’-imïnoacyl complexes (III) in 19-8576 yields (Table 1). The latter complexes (III) cari also be synthesized by room temperaturc reaction of the imidoyl halide with the cobalt tetracarbonyl anion in the presence of an equimolar amount of trïphenylphosphine (method B). The beautifully crystalline 9’ -iminoacylcobalt complexes, identifïed on the basis of
_
PI1
Ph
p.CQH,
Ph
pCH,OC,H,
Ph
Ph
C,H5
YB
66.16 (66.66)
66.10 (66.37)
116.0-117.0
76(7f3)g
Y
66
3G
Y
4042 (4,43)
2.26 (2.68)
2.22 (2,61)
4,73 (4069)
3,90
2.31 (2.26)
2,07 (2.39)
2.03 (2.03)
(3863)
4,40 (4,30)
70.01 (69.76)
6661 (67.06)
99.6-102.0
44f
6,46 (6.41)
2,22 (2.34)
4,34 (4,64)
70.26 (70.12)
63,lO (67.92)
N
1.1
C
Anal, (Pound (calc’d) (96))
100.0-102.6
106,6-103.0
19e
Y
YB
63.0-87,O
43(42)
98.6-100.6
M,P. (“C) dec,
Y
(a)
Colo~ e Yield k
1612m
3,73(s,3H,CH,), 7.10-7.60(m,20H, aromatic)
1616m
1633m
6.90-7.60(m)
1603m
1,33(1,3H,CH,,J 7.0 Hz), 3,lO (q,2H, CH,), 6.80-7.6O(m,20H,aromatlc)
1,17(t,6H,J 7.0 Hz methyls of eolvated ether) 3.60(q14H,methylenes of solvated ether), 3,82(s,3H,OCH,) 6.70-7.70(m, 24Hqomatic) 6.90-7.70(m)
1620m
1626m 1642m
2,46(s,3H,CH,), aromatic)
WN)
2040~ 1977s 1960(sh) 1961s 2040~ 1979s 1971(sh) 1960s 2040~ 1977s 1943s 2040~ 1978s 1967s 2038~ 1976s 1942s 2036m 1971s 1956(sh) 1948s
6.90-7,70(m,24H,
‘H NMR. 6 (ppm) d
WO)
IRC (cm-‘)
-
. - -
.- -
.._ -
_ - --
a Y = Yellow, YB = Yellow-brown. h YieIds given are those obtained usina method A. Yields obtained usina method B are givcn in brackets. ‘KBr dise. d CDC], With tetramethylsilane as intemnl standard. ’ Thie complex, after recrystallization from ether/hcxane, was solvated by a molecule of ether, f Molccular weight: found, 081; calcd,, 686.0. g Molecular welght: found, 664, calcd,, 037.4.
CH,
@H,C,H,
Ph
Ph
RZ
n’
HI
YIELD, ANALYTICAL AND SPECTRAL DATA FOR III
TABLE 1
8
Ph
CI
co(co)4-
I
PhC=NPh
+
R'C=NR2
+
CO(COJS PPh,-
Na +
THF 0-25°C
I
CI PPh3
(II)
\
Co(C0)4_Na+ PPh3_
,
THF,
/
tm’
r-t.
analytical and spectral data (Table i), are stable under nitrogen in the solid state, but gradually decompose in solution. Terminal metal carbonyl stretching bands were observed in the infrared spectraat2035-2040w,19'71-1979s,and1942-1957scm-', wïth the carbon nitrogen double bondstretchingabsorption occurring at1608-1633 cm-’ (KBr disc). The latter absorption occurs in the same region as that for other n’-iminoacylmetal carbonyl complexes [ 51; Proton magnetic resonance spectra are also in accord with the assigned structure_ The appearance of on17 one methyl signal for III, R’ = Ph, R2 = CH,, and one ethyl pattem for III, R’ = C,H, , R* = Ph, indicates the existence of III in only one stereoisomeric form, i.e., with the lone pair (rather than R2) qyn to the very bulky Co(C0)3PPh3 group. Molecular ion peaks were not observed in the mass spectra of III. However, vapor phase osmometric molecular weight determinations of III, R’ = R2 = Ph, and III, R' = C,H5, R2 = Ph supportthe mononuclearnature ofthese complexes.
The following procedures are representative of each method: (A) TO 1.20 mmol of PhC(Cl)=NC,H,CH,-p in THF (5 ml) was added 1.23 mmol of NaCo(CO)JPPh, [6] in THF (50 ml) at 0°C. The reaction mixture was allowed to warm to room temperature, and then stirred ovemight. The SO~Ution was concentrated in vacuo to ca. 10 ml, metlnylene chloride (10 ml) was added, ancl then sodium chloride was removed by filtration. Evaporation of the filtrate gave a brown oil which was dissolved in a mixture of methylene chloride (1.0 ml) and ether (5 ml), and then hexane (5 ml) was added. The solution, after filtration to remove small amounts of impurities, was cooled to -45°C to give III, R’ = Ph, R* = p-CH,C,H,. Yellow mica-like plates (307 mg) of the 17’ -iminoacyl complex were obtained on recrystallization from ether (7 ml) and hexane (3 ml). (B) TO a THF solution (7.5 ml) of NaCo(CO), (1.27 mmol) was added 0.381 g (1.5 mmol) of PPh, and 0.344 g (1.5 mmol) of II, R’ = Ph, R* = p-CH,C,H,. The reaction mixture was stirred for two days at room temperature, concentrated, and then treated with methylene chloride (5 ml) and ether (5 ml)_ The solution was filtered, the solid was washed with ether (1 ml) and the washing was added to the filtrate. A brown oil, obtained on filtrate evaporation, was worked-up as described for method A to give 330 mg of analytically pure III, R’ = Ph, R* = p-CH&H,. Aclsnowledgment We are grateful to the Natural Sciences and Engineering Research Council of Canada for support of this work. References 1 2 3 4 5 6
R_D_ Adams. D-F_ Chodosh aod N-M. Golembeskï. J. Organometal. Chem., 139 (1977) C39. K B-er and J_Wachter. J. OrganometaL Chem., 155 (1978)(229. R_D_ Adams and D.F. Chodosh. Inorg. Chem.. 17 (1978) 41. W.R. Roper. G.E. Taylor, J.M. Waters and L.J. Wright. J. Organometal Chem.. 157 (1978) C27. R_D. Adams and D.F. Chodosh. J. Amer. Chem. Soc., SS (1977) 6544. W. Hieber and E. Lïïdner. Chem. Ber.. 94 (196i) 1417.
Preliminary
communication
SYNTHETIC APPROACHES COMPLEXES
TO q l-IMINOACYLCOBALT
CARBONYL
HOWARD ALPER* and MASATO TANAKA Department
oi Chemzktry, University of Ottawa, Ottawa, Ontario, KlN 9B4 (Canada)
(Received January 9th, 1979)
§ummary
Reaction of imidoyl chlorides with triphenylphosphinecobalt tricarbonyl anion or wïth cobalt tetracarbonyl anion in the presence of triphenylphosphine affords Q’-iminoacylcobalt carbonyl complexes in 19-85% yields.
Several recent publications have descrïbed the reactions of imidoyl chlorides wîth metal carbonyl anions. While cyclopentadienyltungsten tricarbonyl anion and the iron dicarbonyl anions form 72’ -iminoacyl complexes on reaction with imidoyl chlorides, the cyclopentadienylmolybdenum tricarbonyl anion bas been reported ta react wïth PhC(Cl)=NPh and PhC(Cl)=NCII, to give, respectively, $-iminoacyl complexes [l] and a complex derived from two imidoyl and one anion units [Z]. Other examples of q*-iminoacylmetal carbonyl complexes have been described very recently [ 3,4] _ Adams and coworkers [l] found that imidoyl chloride-metal carbonyl anion reactions were generally rapid (complete in 30 minutes or less). However, the cobalt tetracarbonyl anion-imidoyl chloride reaction proved to be exceptionally slow, requiring approximately two days for completion, and affording a binuclear cobalt complex (1) containing coupled imidoyl fragments. No l/l mononuclear complex was -formed. This communication describes the first examples of g1 -iminoacylcobalt complexes, prepared by two simple, mild, and convenient methods. Treatment of a series of imidoyl chlorides (II) with triphenylphosphinecobalt tricarbonyl anion (generated by sodium amalgam reduction of bis(triphenylphosphine)dicobalt hexacarbonyl) in rigorously dry tetrahydrofuran (THF) at 0°C (method A), affords the v’-imïnoacyl complexes (III) in 19-8576 yields (Table 1). The latter complexes (III) cari also be synthesized by room temperaturc reaction of the imidoyl halide with the cobalt tetracarbonyl anion in the presence of an equimolar amount of trïphenylphosphine (method B). The beautifully crystalline 9’ -iminoacylcobalt complexes, identifïed on the basis of
_
PI1
Ph
p.CQH,
Ph
pCH,OC,H,
Ph
Ph
C,H5
YB
66.16 (66.66)
66.10 (66.37)
116.0-117.0
76(7f3)g
Y
66
3G
Y
4042 (4,43)
2.26 (2.68)
2.22 (2,61)
4,73 (4069)
3,90
2.31 (2.26)
2,07 (2.39)
2.03 (2.03)
(3863)
4,40 (4,30)
70.01 (69.76)
6661 (67.06)
99.6-102.0
44f
6,46 (6.41)
2,22 (2.34)
4,34 (4,64)
70.26 (70.12)
63,lO (67.92)
N
1.1
C
Anal, (Pound (calc’d) (96))
100.0-102.6
106,6-103.0
19e
Y
YB
63.0-87,O
43(42)
98.6-100.6
M,P. (“C) dec,
Y
(a)
Colo~ e Yield k
1612m
3,73(s,3H,CH,), 7.10-7.60(m,20H, aromatic)
1616m
1633m
6.90-7.60(m)
1603m
1,33(1,3H,CH,,J 7.0 Hz), 3,lO (q,2H, CH,), 6.80-7.6O(m,20H,aromatlc)
1,17(t,6H,J 7.0 Hz methyls of eolvated ether) 3.60(q14H,methylenes of solvated ether), 3,82(s,3H,OCH,) 6.70-7.70(m, 24Hqomatic) 6.90-7.70(m)
1620m
1626m 1642m
2,46(s,3H,CH,), aromatic)
WN)
2040~ 1977s 1960(sh) 1961s 2040~ 1979s 1971(sh) 1960s 2040~ 1977s 1943s 2040~ 1978s 1967s 2038~ 1976s 1942s 2036m 1971s 1956(sh) 1948s
6.90-7,70(m,24H,
‘H NMR. 6 (ppm) d
WO)
IRC (cm-‘)
-
. - -
.- -
.._ -
_ - --
a Y = Yellow, YB = Yellow-brown. h YieIds given are those obtained usina method A. Yields obtained usina method B are givcn in brackets. ‘KBr dise. d CDC], With tetramethylsilane as intemnl standard. ’ Thie complex, after recrystallization from ether/hcxane, was solvated by a molecule of ether, f Molccular weight: found, 081; calcd,, 686.0. g Molecular welght: found, 664, calcd,, 037.4.
CH,
@H,C,H,
Ph
Ph
RZ
n’
HI
YIELD, ANALYTICAL AND SPECTRAL DATA FOR III
TABLE 1
8
Ph
CI
co(co)4-
I
PhC=NPh
+
R'C=NR2
+
CO(COJS PPh,-
Na +
THF 0-25°C
I
CI PPh3
(II)
\
Co(C0)4_Na+ PPh3_
,
THF,
/
tm’
r-t.
analytical and spectral data (Table i), are stable under nitrogen in the solid state, but gradually decompose in solution. Terminal metal carbonyl stretching bands were observed in the infrared spectraat2035-2040w,19'71-1979s,and1942-1957scm-', wïth the carbon nitrogen double bondstretchingabsorption occurring at1608-1633 cm-’ (KBr disc). The latter absorption occurs in the same region as that for other n’-iminoacylmetal carbonyl complexes [ 51; Proton magnetic resonance spectra are also in accord with the assigned structure_ The appearance of on17 one methyl signal for III, R’ = Ph, R2 = CH,, and one ethyl pattem for III, R’ = C,H, , R* = Ph, indicates the existence of III in only one stereoisomeric form, i.e., with the lone pair (rather than R2) qyn to the very bulky Co(C0)3PPh3 group. Molecular ion peaks were not observed in the mass spectra of III. However, vapor phase osmometric molecular weight determinations of III, R’ = R2 = Ph, and III, R' = C,H5, R2 = Ph supportthe mononuclearnature ofthese complexes.
The following procedures are representative of each method: (A) TO 1.20 mmol of PhC(Cl)=NC,H,CH,-p in THF (5 ml) was added 1.23 mmol of NaCo(CO)JPPh, [6] in THF (50 ml) at 0°C. The reaction mixture was allowed to warm to room temperature, and then stirred ovemight. The SO~Ution was concentrated in vacuo to ca. 10 ml, metlnylene chloride (10 ml) was added, ancl then sodium chloride was removed by filtration. Evaporation of the filtrate gave a brown oil which was dissolved in a mixture of methylene chloride (1.0 ml) and ether (5 ml), and then hexane (5 ml) was added. The solution, after filtration to remove small amounts of impurities, was cooled to -45°C to give III, R’ = Ph, R* = p-CH,C,H,. Yellow mica-like plates (307 mg) of the 17’ -iminoacyl complex were obtained on recrystallization from ether (7 ml) and hexane (3 ml). (B) TO a THF solution (7.5 ml) of NaCo(CO), (1.27 mmol) was added 0.381 g (1.5 mmol) of PPh, and 0.344 g (1.5 mmol) of II, R’ = Ph, R* = p-CH,C,H,. The reaction mixture was stirred for two days at room temperature, concentrated, and then treated with methylene chloride (5 ml) and ether (5 ml)_ The solution was filtered, the solid was washed with ether (1 ml) and the washing was added to the filtrate. A brown oil, obtained on filtrate evaporation, was worked-up as described for method A to give 330 mg of analytically pure III, R’ = Ph, R* = p-CH&H,. Aclsnowledgment We are grateful to the Natural Sciences and Engineering Research Council of Canada for support of this work. References 1 2 3 4 5 6
R_D_ Adams. D-F_ Chodosh aod N-M. Golembeskï. J. Organometal. Chem., 139 (1977) C39. K B-er and J_Wachter. J. OrganometaL Chem., 155 (1978)(229. R_D_ Adams and D.F. Chodosh. Inorg. Chem.. 17 (1978) 41. W.R. Roper. G.E. Taylor, J.M. Waters and L.J. Wright. J. Organometal Chem.. 157 (1978) C27. R_D. Adams and D.F. Chodosh. J. Amer. Chem. Soc., SS (1977) 6544. W. Hieber and E. Lïïdner. Chem. Ber.. 94 (196i) 1417.