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Selenocarbonyl complexes of iridium(I) and iridium(III). Synthesis and reactions of IrCl(CSe)(PPh3)2
c97
Journal of Organometallic Chemistry, 252 (1983) C97-Cl00 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands
Preliminary
communication
SELENOCARBONYL COMPLEXES OF IRIDIUM(I) AND IRIDIUM(II1). SYNTHESIS AND REACTIONS OF IrC1(CSe)(PPh3),
W.R. ROPER* Department
and K.G. TOWN
of Chemistry,
University of Auckland,
Auckland
(New Zealand)
(Received May 20th, 1983)
Summary
A five-step conversion of IrCl(CO)(PPh,), into IrC1(CSe)(PPh,)2 via Ir(p2 -CSe2)C1(CO)(PPh,), is described. IrC1(CSe)(PPh3)2 is oxidized by Cl2 to IrC13(CSe)(PPhs)2 and by O2 to Ir(v2 -02)C1(CSe)(PPh3)2, and reaction with Ag+ in MeCN gives [ Ir( CSe)(MeCN)(PPhJ )2] +. NaBH4 in the presence of PPhB reduces IrC1(CSe)(PPhj)2 completely to IrH2(SeMe)(PPhB)3 and the v2 -CSe2 adduct, Ir(~2-CSe2)Cl(CSe)(PPh,)2, with Me1 forms the metallacycle [Ir(C[SeMe]SeC[SeMe])I,(PPh,),]+.
Interesting discoveries have followed the study of transition metal thiocarbonyl complexes. These include (i) the alkylation of S in low valent CS complexes which constitutes an important route to thiocarbyne complexes [l] , (ii) the involvement of CS in migratory-insertion reactions which has led to thioacyl groups [ 21 and for the special case of hydride migration, to thioformyl and thence to formyl ligands [ 31, (iii) the formation of unsaturated metallacycles, e.g. “metallabenzenes” [ 41 and “metallacyclobutadienes” [ 51. Similar chemistry must await discovery for selenocarbonyl complexes but the growth of this area is restricted by generally unsatisfactory synthetic routes to selenocarbonyl-containing starting materials. Presently available methods rely on modification and fragmentation of q2 -CSe2 [ 61 or v2 -CSeS [ 71 and substitution reactions of Ccl2 complexes [ 8,9] . An obvious synthetic target is IrC1(CSe)(PPh3)2 especially in view of the important role IrCl(CO)(PPh,), has played in organometallic chemistry and the fact that IrC1(CS)(PPhJ), was one of the first thiocarbonyl complexes to be described. As a first step in the examination of the selenocarbonyl chemistry of iridium we describe here a straightforward five-step conversion of IrCl( CO)(PPhB )2 to IrC1(CSe)(PPhj), and some further simple reactions of this new complex. The preparation of IrC1(CSe)(PPhJ)2 follows the steps outlined in Scheme 1. 0022-328X/83/$03.00
0 1983 Elsevier Sequoia S.A.
CSe,
Ir-CO
Cl -
Se
C!
I
\I/ ‘I’L ‘\\,, Ir
co
I
Mel
iI” Cl
\I/
Se
Ir
CO 4’
C-
SeMe
L
~
!ieMe
/
I-ICI gas~CBHb (-CO,
MeSeHf
t
Cl
L
\I/ ‘I’
L H NEt3CHCI)
Ir
Cl
SCHEME
-
c
a-
Ir -----
HCI CSe
1. Conversion of IrCW!O?(PPh,f,
to IrCl(CSe)(PPh,), CL = PPh&
The n 2 -CSe2 adduct has been described previously [lo]. Methyla~on with MeI yields the n2 -diselenomethylester complex which is readily converted to a 1)1 -CSe,Me complex by the introduction of hydride ligand using NaBH,. The synthesis so far parallels that already described for I~l(CS)(PPh~)~ 1111 but Ir(q?’-CSe~Me)HCl(C~)(PPh~)~ does not eliminate MeSeH thermally. However, anhydrous HCI gas in benzene solution does cleave MeSeH and form IrHCl~(CSe~(PPh~)~ . This colourless material is easily dehydroh~ogenated with a base like triethylamine to IrCl(CSe)(PPh3)2 which forms orange, needle-like crystals, m.p. 247-249°C. There is a strong IR absorption at 1198 cm-’ which must be associated largely with C-Se stretching. p(CSe)
c99 TABLE 1 IR DATA Compound
c FOR
IRIDIUM SELENOCARBONYL
b
Other bands
v(CSe)
-._
Ir(qs-CSe, )Cl(CO)(PPh, )s [Ir($ -CSe, Me)Cl(CO)(PPh, )s )ClO4 Ir(q* -CSe, Me)HCl(CO)(PPh, )s IrCl(CSe)(PPh,), IrHCl, (CSe)(PPh, )s IrCl, (CSe)(PPh, )s IIr(CSe)(MeCN)(PPh,), I ClO,
1006. 1000 860 1198 1200 1201 1184 1145
CIr(CSe)(CO), (PPbs )s I ClO, IrH, (SeMe)(PPh, )s Ir(4 )CWSe)(PPb, )s Ir(q -CSe, )Cl(CSe)(PPh, )s C&CCSeMel SeCCSeMel )Ia (PPh, )s 1 ClO, c cm-’
COMPLEXES
995
1165 1175,1010 863
2026,2000,1990, U(C0) 2045, v(C0) 2046, v(C0); 2000, v(IrH) 2240, v(IrH) 2320, 2060. 2130,
u(CN) 2000, v(C0) 2050, u(IrH)
848, ~(0, )
measured as Nujol mulls. b All compounds have satisfactory elemental analyses.
band8 for other selenocarbonyl complexes reported here are collected in Table 1. Like IrC1(CO)(PPh3)2;IrC1(CSe)(PPh3)2 is readily oxidised by Cl2 to IrCl,(CSe)(PPh3)2, with oxygen forms a dioxygen adduct Ir(02)C1(CSe)(PPh3 h, and with AgC104 in acetonitrile forms [Ir(CSe)(MeCN)(PPh,),] C104. From L
*
C’2
I
Cl-Ir-cse I
J
L
AgC104 MeCN
H&L H/Iii,,, L
SCHEME 2. Reactions of IrCl(CSe)(PPh,),
(L = PPh,).
Cl00
this cation other cations, e.g. [Ir(CSe)(CO),(PPh,)J + can be readily derived. Unlike IrCl( CO)(PPh, )2, however, it should be noted that v(CSe) values for these adducts (see Table 1) do not necessarily rise upon oxidation or conversion to a cation. In fact the dioxygen adduct has v(CSe) lowered by 33 cm’-’ from IrCl(CSe)(PPh,),. This must reflect extensive mixing of v(CSe) modes with lower energy modes particularly v[Ir-(CSe)] . v(CSe) is not, therefore, a useful measure of metal electron density in the way in which v(C0) is so useful. Reaction of IrCl(CSe)(PPh,), (Scheme 2) with NaBH4 in the presence of PPh,, which in the case of IrCl(CO)(PPh,), and IrCl(CS)(PPh,), leads to IrH(CO)(PPh,), and IrH(CS)(PPh,), , respectively, leads here instead to complete reduction of the selenocarbonyl ligand and the final product is IrH,(SeMe)(PPh,), . This reduction must proceed via selenoformaldehydecoordinated intermediates. Osmium selenoformaldehyde complexes are now known [ 121. CSez reacts with IrCl(CSe)(PPh,), to form the adduct Ir(n2 -CSe,)Cl(CSe)(PPh,), . Methylation of the v2 -CSe, in this molecule with Me1 giving [ Ir(q 2 -CSe, Me)Cl( CSe)( PPh3 )2] +, is followed by immediate condensation between the diselenomethyl-ester ligand and CSe and further methylation at Se forms the novel metallacycle [ Ir(C[ SeMe] SeC[ SeMe] )I, (PPh, )2] +. Similar condensations occur between thiocarboxamide and thiocarbonyl ligands and the cyclic ligand resulting in this case has been structurally characterised [ 131. The general reaction may be written: X
LnM
XMe
1
t
TX \
-
c=x
I
Y
-.J (X
=
S,
Se,Y
=
NR,,
SMe,
SeMe.etc.1
References
7 8 9 10 11 12 13
B.D. Dombek and R.J. Angelici, Inor& Chem., 15 (1976) 2397. G.R. Clark, T.J. Collins, K. Marsden and W.R. Roper, J. Organomet. Chem.. 157 (1978) C23. T.J. Collins and W.R. Roper, J. Organomet. Chem., 159 (1978) 73. G.P. BIIiott, W.R. Roper and J.M. Waters, J. Chem. Sot. Chem. Commun.. (1982) 811. G.P. Elliott, and W.R. Roper. J. Organomet. Chem., 250 (1983) I.S. Butler, D. Cozak and S.R. Stobsrt. Inorg. Chem.. 16 (1977) 1779; G.R. Clark, K.R. Gmndy, R.O. Hsrris, S.M. James and W.R. Roper, J. Organomet. Chem.. 90 (1975) C37. P.J. Brothers, C.E.L. Headford and W.R. Roper. J. Organomet. Chem., 195 (1980) C29. G.R. Clark, K. Marsden. W.R. Roper and L.J. Wright, J. Amer. Chem. Sot.. 102 (1980) 1206. W.R. Roper and A.H. Wright, J. Organomet. Chem.. 233 (1982) C59. K. Kawakami, Y. Ozaki and T. Tanaka, J. Organomet. Chem.. 69 (1974) 151. T.J. Collins, W.R. Roper and K.G. Town. J. Organomet. Chem., 121 (1976) C41. C.E.L. Headford and W.R. Roper, J. Organomet. Chem.. 244 (1983) C53. G.R. Clark, T.J. Collins. D. HalI, S.M. James and W.R. Roper, J. Organomet. Chem.. 141 (1977) C5.
Journal of Organometallic Chemistry, 252 (1983) C97-Cl00 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands
Preliminary
communication
SELENOCARBONYL COMPLEXES OF IRIDIUM(I) AND IRIDIUM(II1). SYNTHESIS AND REACTIONS OF IrC1(CSe)(PPh3),
W.R. ROPER* Department
and K.G. TOWN
of Chemistry,
University of Auckland,
Auckland
(New Zealand)
(Received May 20th, 1983)
Summary
A five-step conversion of IrCl(CO)(PPh,), into IrC1(CSe)(PPh,)2 via Ir(p2 -CSe2)C1(CO)(PPh,), is described. IrC1(CSe)(PPh3)2 is oxidized by Cl2 to IrC13(CSe)(PPhs)2 and by O2 to Ir(v2 -02)C1(CSe)(PPh3)2, and reaction with Ag+ in MeCN gives [ Ir( CSe)(MeCN)(PPhJ )2] +. NaBH4 in the presence of PPhB reduces IrC1(CSe)(PPhj)2 completely to IrH2(SeMe)(PPhB)3 and the v2 -CSe2 adduct, Ir(~2-CSe2)Cl(CSe)(PPh,)2, with Me1 forms the metallacycle [Ir(C[SeMe]SeC[SeMe])I,(PPh,),]+.
Interesting discoveries have followed the study of transition metal thiocarbonyl complexes. These include (i) the alkylation of S in low valent CS complexes which constitutes an important route to thiocarbyne complexes [l] , (ii) the involvement of CS in migratory-insertion reactions which has led to thioacyl groups [ 21 and for the special case of hydride migration, to thioformyl and thence to formyl ligands [ 31, (iii) the formation of unsaturated metallacycles, e.g. “metallabenzenes” [ 41 and “metallacyclobutadienes” [ 51. Similar chemistry must await discovery for selenocarbonyl complexes but the growth of this area is restricted by generally unsatisfactory synthetic routes to selenocarbonyl-containing starting materials. Presently available methods rely on modification and fragmentation of q2 -CSe2 [ 61 or v2 -CSeS [ 71 and substitution reactions of Ccl2 complexes [ 8,9] . An obvious synthetic target is IrC1(CSe)(PPh3)2 especially in view of the important role IrCl(CO)(PPh,), has played in organometallic chemistry and the fact that IrC1(CS)(PPhJ), was one of the first thiocarbonyl complexes to be described. As a first step in the examination of the selenocarbonyl chemistry of iridium we describe here a straightforward five-step conversion of IrCl( CO)(PPhB )2 to IrC1(CSe)(PPhj), and some further simple reactions of this new complex. The preparation of IrC1(CSe)(PPhJ)2 follows the steps outlined in Scheme 1. 0022-328X/83/$03.00
0 1983 Elsevier Sequoia S.A.
CSe,
Ir-CO
Cl -
Se
C!
I
\I/ ‘I’L ‘\\,, Ir
co
I
Mel
iI” Cl
\I/
Se
Ir
CO 4’
C-
SeMe
L
~
!ieMe
/
I-ICI gas~CBHb (-CO,
MeSeHf
t
Cl
L
\I/ ‘I’
L H NEt3CHCI)
Ir
Cl
SCHEME
-
c
a-
Ir -----
HCI CSe
1. Conversion of IrCW!O?(PPh,f,
to IrCl(CSe)(PPh,), CL = PPh&
The n 2 -CSe2 adduct has been described previously [lo]. Methyla~on with MeI yields the n2 -diselenomethylester complex which is readily converted to a 1)1 -CSe,Me complex by the introduction of hydride ligand using NaBH,. The synthesis so far parallels that already described for I~l(CS)(PPh~)~ 1111 but Ir(q?’-CSe~Me)HCl(C~)(PPh~)~ does not eliminate MeSeH thermally. However, anhydrous HCI gas in benzene solution does cleave MeSeH and form IrHCl~(CSe~(PPh~)~ . This colourless material is easily dehydroh~ogenated with a base like triethylamine to IrCl(CSe)(PPh3)2 which forms orange, needle-like crystals, m.p. 247-249°C. There is a strong IR absorption at 1198 cm-’ which must be associated largely with C-Se stretching. p(CSe)
c99 TABLE 1 IR DATA Compound
c FOR
IRIDIUM SELENOCARBONYL
b
Other bands
v(CSe)
-._
Ir(qs-CSe, )Cl(CO)(PPh, )s [Ir($ -CSe, Me)Cl(CO)(PPh, )s )ClO4 Ir(q* -CSe, Me)HCl(CO)(PPh, )s IrCl(CSe)(PPh,), IrHCl, (CSe)(PPh, )s IrCl, (CSe)(PPh, )s IIr(CSe)(MeCN)(PPh,), I ClO,
1006. 1000 860 1198 1200 1201 1184 1145
CIr(CSe)(CO), (PPbs )s I ClO, IrH, (SeMe)(PPh, )s Ir(4 )CWSe)(PPb, )s Ir(q -CSe, )Cl(CSe)(PPh, )s C&CCSeMel SeCCSeMel )Ia (PPh, )s 1 ClO, c cm-’
COMPLEXES
995
1165 1175,1010 863
2026,2000,1990, U(C0) 2045, v(C0) 2046, v(C0); 2000, v(IrH) 2240, v(IrH) 2320, 2060. 2130,
u(CN) 2000, v(C0) 2050, u(IrH)
848, ~(0, )
measured as Nujol mulls. b All compounds have satisfactory elemental analyses.
band8 for other selenocarbonyl complexes reported here are collected in Table 1. Like IrC1(CO)(PPh3)2;IrC1(CSe)(PPh3)2 is readily oxidised by Cl2 to IrCl,(CSe)(PPh3)2, with oxygen forms a dioxygen adduct Ir(02)C1(CSe)(PPh3 h, and with AgC104 in acetonitrile forms [Ir(CSe)(MeCN)(PPh,),] C104. From L
*
C’2
I
Cl-Ir-cse I
J
L
AgC104 MeCN
H&L H/Iii,,, L
SCHEME 2. Reactions of IrCl(CSe)(PPh,),
(L = PPh,).
Cl00
this cation other cations, e.g. [Ir(CSe)(CO),(PPh,)J + can be readily derived. Unlike IrCl( CO)(PPh, )2, however, it should be noted that v(CSe) values for these adducts (see Table 1) do not necessarily rise upon oxidation or conversion to a cation. In fact the dioxygen adduct has v(CSe) lowered by 33 cm’-’ from IrCl(CSe)(PPh,),. This must reflect extensive mixing of v(CSe) modes with lower energy modes particularly v[Ir-(CSe)] . v(CSe) is not, therefore, a useful measure of metal electron density in the way in which v(C0) is so useful. Reaction of IrCl(CSe)(PPh,), (Scheme 2) with NaBH4 in the presence of PPh,, which in the case of IrCl(CO)(PPh,), and IrCl(CS)(PPh,), leads to IrH(CO)(PPh,), and IrH(CS)(PPh,), , respectively, leads here instead to complete reduction of the selenocarbonyl ligand and the final product is IrH,(SeMe)(PPh,), . This reduction must proceed via selenoformaldehydecoordinated intermediates. Osmium selenoformaldehyde complexes are now known [ 121. CSez reacts with IrCl(CSe)(PPh,), to form the adduct Ir(n2 -CSe,)Cl(CSe)(PPh,), . Methylation of the v2 -CSe, in this molecule with Me1 giving [ Ir(q 2 -CSe, Me)Cl( CSe)( PPh3 )2] +, is followed by immediate condensation between the diselenomethyl-ester ligand and CSe and further methylation at Se forms the novel metallacycle [ Ir(C[ SeMe] SeC[ SeMe] )I, (PPh, )2] +. Similar condensations occur between thiocarboxamide and thiocarbonyl ligands and the cyclic ligand resulting in this case has been structurally characterised [ 131. The general reaction may be written: X
LnM
XMe
1
t
TX \
-
c=x
I
Y
-.J (X
=
S,
Se,Y
=
NR,,
SMe,
SeMe.etc.1
References
7 8 9 10 11 12 13
B.D. Dombek and R.J. Angelici, Inor& Chem., 15 (1976) 2397. G.R. Clark, T.J. Collins, K. Marsden and W.R. Roper, J. Organomet. Chem.. 157 (1978) C23. T.J. Collins and W.R. Roper, J. Organomet. Chem., 159 (1978) 73. G.P. BIIiott, W.R. Roper and J.M. Waters, J. Chem. Sot. Chem. Commun.. (1982) 811. G.P. Elliott, and W.R. Roper. J. Organomet. Chem., 250 (1983) I.S. Butler, D. Cozak and S.R. Stobsrt. Inorg. Chem.. 16 (1977) 1779; G.R. Clark, K.R. Gmndy, R.O. Hsrris, S.M. James and W.R. Roper, J. Organomet. Chem.. 90 (1975) C37. P.J. Brothers, C.E.L. Headford and W.R. Roper. J. Organomet. Chem., 195 (1980) C29. G.R. Clark, K. Marsden. W.R. Roper and L.J. Wright, J. Amer. Chem. Sot.. 102 (1980) 1206. W.R. Roper and A.H. Wright, J. Organomet. Chem.. 233 (1982) C59. K. Kawakami, Y. Ozaki and T. Tanaka, J. Organomet. Chem.. 69 (1974) 151. T.J. Collins, W.R. Roper and K.G. Town. J. Organomet. Chem., 121 (1976) C41. C.E.L. Headford and W.R. Roper, J. Organomet. Chem.. 244 (1983) C53. G.R. Clark, T.J. Collins. D. HalI, S.M. James and W.R. Roper, J. Organomet. Chem.. 141 (1977) C5.