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Reactions of [Mo(N2)2(dppe)2] with organic isocyanates
C6 Journal of Organometallic Chemistry, 231(1982) C6-C8 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands
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REACTIONS
OF [Mo(N, )* (dppe), ] WITH ORGANIC ISOCYANATES
FERRUCCIOMINZONI,
CORRADO
PELIZZI
and GIOVANNI
PREDIERI+
Istituto di Chimica Generale ed Inorganica dell’Universi& e Centro di Studio per la Strutfuristica Diffmttometrica de2 C.N.R., Via M. D’Azeglio, 85, 43100 Parma (Ita!y) (Received February lZth, 1982)
The reactions of [Mo(N, ),(dppe), ], (dppe = Ph,PCH, CH2PPh2) with RC,H,NCO (R = H, p-CH,, p-Cl) in benzene under irradiation produces IMo(RGH~NCO)~ (dppe), 1 in good yields. Comparison of the infrared data for these complexes, with those previously reported for metal complexes of COzlike molecules suggest a s2-C,O coordination to the metal. The dinitrogen complex trans-[Mo(N,),(dppe),] (I) undergoes a variety of substitution reactions in which dinitrogen is partly or totally lost [l]. Ligands such as CO [Z] , RNC [S], RCN [4], P(OR)s [ 51 are able to give o-coordination at the electron-rich Mo(dppe), site, whereas ethylene and tetracyanoethylene (tcne) give q2-coordination, in [Mo(C,H,)(dppe),] and [Mo(tcne),(dppe)2 1, respectively [6]. Carbon dioxide reacts with cis-[Mo(N, )z (PMe,Ph), 1, but not with I, to form a complex formulated as [Mo(CO,),(PMe,Ph),], (IR: 1760 cm-‘) [7], in which COz is probably T2-bonded to the metal center_ We now report that aromatic isocyanates, which are C02-like molecules, react with I, under irradiation, to give well defined substitution products of formula [Mo(RC,H,NCO),(dppe),], (R = H, p-CH3, p-Cl), according to the equation: CMo(N, )2 (dppe),
1 + 2RWbNCO z
EJWRC6H4NC0)2 @web 1 + ZN,
Aliphatic isocyanates, such as the methyl and t-butyl compounds give, after prolonged irradiation, only unchanacterized decomposition powders, whereas preliminary investigation have shown that PhNCS reacts readily with I without irradiation to give an S-containing molybdenum complex and free PhNC*. *[W
does not react with PhNCS under the same conditions
In ContESt. it
to produce a brown complex formulated as [W(N,)(C,H,NCO)(dppe),lr but the low yield and’the incomplete reproducibility
investigationis needed.
ICaCtS
With
(IR: 2000% of the results mean that Mher
c7 TABLE
1
CHARACTERIZATION R=
DATA
FOR
IR bands
(cm-‘)
mm)
WW
other
P-CH,
162Ovs 1620~s
P-Cl
1620~s
157ovs 1588~s 1568~s
1485s. 1495vs. 1480s.
H
a All these complexes
gave satisfactory
THE
COMPLEXES
1431s. 1431s. 1431ms.
1226ms. 1223m. 1235m.
elemental
(C.H.N)
[Mo(RC,H,NCO
1092m 1091m 1091m
j,(dppe),]
Color
M.P.
yellow YdlOW yellow
llO(dec.) llO(dec.) 130(dec.)
<=C>
analyses.
Characterization data for the isocyanate complexes are summarized in Table 1. The major feature in the IR spectra of these compounds is the absence of any bands near 2200 cm-’ attributable to the antisymmetric vibration of the heterocumulenes, and the presence of two very strong bands near 1600 cm-‘. The first band, assignable to v(CO), (1620 cm-l), is completely independent of the nature of the para-substituent, whereas the second band (near 1570 cm-‘) shows a slight dependence. The values are consistent with s*-coordination of the isocyanates at the metal, but there remains the question of whether the v*linkage involves the CO or the CN bond:
Ph
z2-GO
q2-
C,N-
There are only a few reports in the literature dealing with q2-bonded arobut their reactions with transition metal complexes have recently been reviewed [ 81. Examples of products are [Ni(PPh, )* (PhNCO)] , (v(CO), 2763 cm-l; rl*-C,N suggested), [9] and [RhCI(PCy,),(PhNCO)], (v(CO), 1842 cm-’ ; 4 2-C,N suggested) [lo]; however, no crystal structure determination have appeared to confirm the proposed mode of bonding. On the other hand, the binding modes of diphenylketene, Ph,CCO, in its metal complexes have been clarified by X-ray structure determinations. For example it exhibits a n2-C,O coordination in [Cp,V(Ph,CCO)], (v(CO), 1620 cm-l) [ll], and a q2-C,C linkage in [CpMn(CO),(Ph,CCO)], Y(CO), 1787 cm-‘) [12]. The same low value for v(C0) found in [Cp2V(Ph2CCO)] and in [Mo(RC,H,NCO),(dppe),] strongly suggests a Q*-C,O coordination for the latter also, unlike the reported Ni and Rh complexes, in which PhNCO could be q2-C,N bonded. An X-ray structural analysis, undertaken on the phenyl derivative $Mo(PhNC0)2(dppe),] with the best crystals we were able to obtain, allowed us to locate only the MO atom and four electron density peaks attributable to P atoms. They were arranged in a nearly square planar fashion around the metal, at dis-
matic kocytiates,
._ _
.
.-
_- . _ _._._- __ _ ___ - - -- -
-- .
s.
_.
i..
.--
--_-_
______
__
_
_
C8 tances ranging from 2.52 to 2.55 A. Any attempt to locate the remaining nonhydrogen atoms, including those occupying the apical positions in the MO environment, failed, owing to the paucity of data (only 20% of observed reflections with I > o(l))_ Fxperimental All reactions were carried out under dinitrogen, using standard inert atmosphere techniques. Irradiation of solutions, in Pyrex vessels, were carried out with an Helios-Ital quartz high pressure 125W mercury lamp. Preparation of [Mo(PhNCO), ( dppe)z 1. Procedure A : phenyl isocyanate (2 mmol) was added to an orange benzene solution (20 ml) of I (0.1 mmol) (prepared as in ref. 13). The mixture was irradiated for 6 h at room temperature during which the color changed to yellowish brown. Addition of hexane and cooling gave a yellow microcrysklhne product, which was filtered off, washed, and dried in vacua (70%); (see Table 1). Procedure B: phenyl isocyanate (0.45 mmol) was added to a toluene solution (20 ml) of I (0.15 mmol) and the mixture was stirred at 0°C for 36 h. Hexane was added (15 ml) and the solution was kept at*4°C for two days. The resulting yellow prismatic crystals were filtered off,washed,and driedin vacuo.Analyticaland ‘H NMR data support the formula [Mo(P~NCO)~ (dppe)r ] - PhMe. Crystal data: C,3H66MoNZ02P4, monoclinic, space group P21 /c, a 18.53, b 27.23, c 12.92 & /3 90.2q 2 = 4. The other complexes were prepared, in similar yields, by procedure A_ Acknowledgments. The authors are grateful to Professors G.P. Chiusoli, M. Nardelli and G. Pelizzi for helpful advice. References 1
J. Chatt. J.R. Dilworth and R.L. Richards, Chem. Rev.. 78 (1978) 589. M_ Xidai. I(_ Tominaxi and Y. Uchida. J_ Amer. Chem. Sec.. 94 (1972) 110. 5 J. Chatt. C-M. Elson. A.J.L. Pombeiro. R.L. Richards and G.H.D. Royston, J. Chem. Sot. Dalton, (1978) 165. 4 T. Tatsumi. M. Hidai sod Y. Uchida, Inorg. Chem.. 14 (1975) 2530. 5 F. Minzoni. C_ Pelizzi and G. Frediezi. Tams-Met. Chem.. in press. T. Yamamoto. A. Yamamoto end S. Ekeda. J. Chem. Sot. Dalton. (1974) 1783. 6 T. Ito. T. Kokubo. 7 L Chatt. M. Kubota. G.J_ Leigh. F.C. March. R. Mason and D.J. Yarrow, Chem. Commun., (1974) 1033. 279_ 8 S. Cenini and G. La Monica, Inorg. Cbim_ Acta, 18 (1976) 9 H. Hoberg and J. Korff. J. Organometal. Chem., 150 (1978) C20. 10 H-t&I_ van Gaal and J.P.J_ Verlaan. J_ 0rganometa.L Chem.. 133 (1977) 93. 11 S. Gambarotta. M. PasquaB. C. Floriani, A. Chiesi-Villa and C. Guastini. Inorg. Chem.. 20 (1981) 117x 12 W.A. Hen-mann. Angew. Chem. Internat. Edit., 13 (1974) 335: A.D. Redhouse and W.A. Herrmann, Angew. Chem. Internat. Edit_, 15 (1976) 615. 13 T.A. George and M-E. Noble, Inorg. Chem.. 17 (1978) 1678.
_.-_.
Pr&xkxwy
communication
REACTIONS
OF [Mo(N, )* (dppe), ] WITH ORGANIC ISOCYANATES
FERRUCCIOMINZONI,
CORRADO
PELIZZI
and GIOVANNI
PREDIERI+
Istituto di Chimica Generale ed Inorganica dell’Universi& e Centro di Studio per la Strutfuristica Diffmttometrica de2 C.N.R., Via M. D’Azeglio, 85, 43100 Parma (Ita!y) (Received February lZth, 1982)
The reactions of [Mo(N, ),(dppe), ], (dppe = Ph,PCH, CH2PPh2) with RC,H,NCO (R = H, p-CH,, p-Cl) in benzene under irradiation produces IMo(RGH~NCO)~ (dppe), 1 in good yields. Comparison of the infrared data for these complexes, with those previously reported for metal complexes of COzlike molecules suggest a s2-C,O coordination to the metal. The dinitrogen complex trans-[Mo(N,),(dppe),] (I) undergoes a variety of substitution reactions in which dinitrogen is partly or totally lost [l]. Ligands such as CO [Z] , RNC [S], RCN [4], P(OR)s [ 51 are able to give o-coordination at the electron-rich Mo(dppe), site, whereas ethylene and tetracyanoethylene (tcne) give q2-coordination, in [Mo(C,H,)(dppe),] and [Mo(tcne),(dppe)2 1, respectively [6]. Carbon dioxide reacts with cis-[Mo(N, )z (PMe,Ph), 1, but not with I, to form a complex formulated as [Mo(CO,),(PMe,Ph),], (IR: 1760 cm-‘) [7], in which COz is probably T2-bonded to the metal center_ We now report that aromatic isocyanates, which are C02-like molecules, react with I, under irradiation, to give well defined substitution products of formula [Mo(RC,H,NCO),(dppe),], (R = H, p-CH3, p-Cl), according to the equation: CMo(N, )2 (dppe),
1 + 2RWbNCO z
EJWRC6H4NC0)2 @web 1 + ZN,
Aliphatic isocyanates, such as the methyl and t-butyl compounds give, after prolonged irradiation, only unchanacterized decomposition powders, whereas preliminary investigation have shown that PhNCS reacts readily with I without irradiation to give an S-containing molybdenum complex and free PhNC*. *[W
does not react with PhNCS under the same conditions
In ContESt. it
to produce a brown complex formulated as [W(N,)(C,H,NCO)(dppe),lr but the low yield and’the incomplete reproducibility
investigationis needed.
ICaCtS
With
(IR: 2000% of the results mean that Mher
c7 TABLE
1
CHARACTERIZATION R=
DATA
FOR
IR bands
(cm-‘)
mm)
WW
other
P-CH,
162Ovs 1620~s
P-Cl
1620~s
157ovs 1588~s 1568~s
1485s. 1495vs. 1480s.
H
a All these complexes
gave satisfactory
THE
COMPLEXES
1431s. 1431s. 1431ms.
1226ms. 1223m. 1235m.
elemental
(C.H.N)
[Mo(RC,H,NCO
1092m 1091m 1091m
j,(dppe),]
Color
M.P.
yellow YdlOW yellow
llO(dec.) llO(dec.) 130(dec.)
<=C>
analyses.
Characterization data for the isocyanate complexes are summarized in Table 1. The major feature in the IR spectra of these compounds is the absence of any bands near 2200 cm-’ attributable to the antisymmetric vibration of the heterocumulenes, and the presence of two very strong bands near 1600 cm-‘. The first band, assignable to v(CO), (1620 cm-l), is completely independent of the nature of the para-substituent, whereas the second band (near 1570 cm-‘) shows a slight dependence. The values are consistent with s*-coordination of the isocyanates at the metal, but there remains the question of whether the v*linkage involves the CO or the CN bond:
Ph
z2-GO
q2-
C,N-
There are only a few reports in the literature dealing with q2-bonded arobut their reactions with transition metal complexes have recently been reviewed [ 81. Examples of products are [Ni(PPh, )* (PhNCO)] , (v(CO), 2763 cm-l; rl*-C,N suggested), [9] and [RhCI(PCy,),(PhNCO)], (v(CO), 1842 cm-’ ; 4 2-C,N suggested) [lo]; however, no crystal structure determination have appeared to confirm the proposed mode of bonding. On the other hand, the binding modes of diphenylketene, Ph,CCO, in its metal complexes have been clarified by X-ray structure determinations. For example it exhibits a n2-C,O coordination in [Cp,V(Ph,CCO)], (v(CO), 1620 cm-l) [ll], and a q2-C,C linkage in [CpMn(CO),(Ph,CCO)], Y(CO), 1787 cm-‘) [12]. The same low value for v(C0) found in [Cp2V(Ph2CCO)] and in [Mo(RC,H,NCO),(dppe),] strongly suggests a Q*-C,O coordination for the latter also, unlike the reported Ni and Rh complexes, in which PhNCO could be q2-C,N bonded. An X-ray structural analysis, undertaken on the phenyl derivative $Mo(PhNC0)2(dppe),] with the best crystals we were able to obtain, allowed us to locate only the MO atom and four electron density peaks attributable to P atoms. They were arranged in a nearly square planar fashion around the metal, at dis-
matic kocytiates,
._ _
.
.-
_- . _ _._._- __ _ ___ - - -- -
-- .
s.
_.
i..
.--
--_-_
______
__
_
_
C8 tances ranging from 2.52 to 2.55 A. Any attempt to locate the remaining nonhydrogen atoms, including those occupying the apical positions in the MO environment, failed, owing to the paucity of data (only 20% of observed reflections with I > o(l))_ Fxperimental All reactions were carried out under dinitrogen, using standard inert atmosphere techniques. Irradiation of solutions, in Pyrex vessels, were carried out with an Helios-Ital quartz high pressure 125W mercury lamp. Preparation of [Mo(PhNCO), ( dppe)z 1. Procedure A : phenyl isocyanate (2 mmol) was added to an orange benzene solution (20 ml) of I (0.1 mmol) (prepared as in ref. 13). The mixture was irradiated for 6 h at room temperature during which the color changed to yellowish brown. Addition of hexane and cooling gave a yellow microcrysklhne product, which was filtered off, washed, and dried in vacua (70%); (see Table 1). Procedure B: phenyl isocyanate (0.45 mmol) was added to a toluene solution (20 ml) of I (0.15 mmol) and the mixture was stirred at 0°C for 36 h. Hexane was added (15 ml) and the solution was kept at*4°C for two days. The resulting yellow prismatic crystals were filtered off,washed,and driedin vacuo.Analyticaland ‘H NMR data support the formula [Mo(P~NCO)~ (dppe)r ] - PhMe. Crystal data: C,3H66MoNZ02P4, monoclinic, space group P21 /c, a 18.53, b 27.23, c 12.92 & /3 90.2q 2 = 4. The other complexes were prepared, in similar yields, by procedure A_ Acknowledgments. The authors are grateful to Professors G.P. Chiusoli, M. Nardelli and G. Pelizzi for helpful advice. References 1
J. Chatt. J.R. Dilworth and R.L. Richards, Chem. Rev.. 78 (1978) 589. M_ Xidai. I(_ Tominaxi and Y. Uchida. J_ Amer. Chem. Sec.. 94 (1972) 110. 5 J. Chatt. C-M. Elson. A.J.L. Pombeiro. R.L. Richards and G.H.D. Royston, J. Chem. Sot. Dalton, (1978) 165. 4 T. Tatsumi. M. Hidai sod Y. Uchida, Inorg. Chem.. 14 (1975) 2530. 5 F. Minzoni. C_ Pelizzi and G. Frediezi. Tams-Met. Chem.. in press. T. Yamamoto. A. Yamamoto end S. Ekeda. J. Chem. Sot. Dalton. (1974) 1783. 6 T. Ito. T. Kokubo. 7 L Chatt. M. Kubota. G.J_ Leigh. F.C. March. R. Mason and D.J. Yarrow, Chem. Commun., (1974) 1033. 279_ 8 S. Cenini and G. La Monica, Inorg. Cbim_ Acta, 18 (1976) 9 H. Hoberg and J. Korff. J. Organometal. Chem., 150 (1978) C20. 10 H-t&I_ van Gaal and J.P.J_ Verlaan. J_ 0rganometa.L Chem.. 133 (1977) 93. 11 S. Gambarotta. M. PasquaB. C. Floriani, A. Chiesi-Villa and C. Guastini. Inorg. Chem.. 20 (1981) 117x 12 W.A. Hen-mann. Angew. Chem. Internat. Edit., 13 (1974) 335: A.D. Redhouse and W.A. Herrmann, Angew. Chem. Internat. Edit_, 15 (1976) 615. 13 T.A. George and M-E. Noble, Inorg. Chem.. 17 (1978) 1678.
_.-_.