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Synthetic reversible oxygen- or nitrogen-carrying chelates of nickel(II)
Thermochimica Acta, 197 (1992) 443-451 Elsevier Science Publishers B.V., Amsterdam
443
Synthetic reversible oxygen- or nitrogen-carrying of nickel( II)
chelates
A. Busnot, J.F. IX Querler and J. Yazbeck Laboratoire de Chimie Minirale et Bioinorganique, U.F.R. de Sciences, Universite’ de Caen, Esplanade de la Pair, 14032 Caen Cedex (France)
(Received 7 July 1991)
Abstract
New oxygenated complexes of nickel(I1) with the composition Ni,O,(Imid),A;zNH, or Ni,N,(Imid),,A,, .z’NH,, where Imid represents the imidazole molecule and A the anion of succinic acid, maleic acid or glutaric acid, have been synthesized. The behavior of these salts when heated in air has been studied by thermogravimetric methods and it has been established that in all cases the product of the decomposition is the oxide or the carbonate. Diffuse reflectance spectra are presented. Calculated electronic transitions are in good agreement with those observed. It seems that the nickel ions are in an octahedral environment. INTRODUCTION
Coordination compounds of transition metals with molecular oxygen are currently being studied [l-S]. In a number of cases, these coordination compounds can activate molecular oxygen and catalyse oxidations. Synthetic reversible oxygen-carrying chelates, i.e., chelates that can take up and release molecular oxygen reversibly, have been of interest as model compounds in the study of the reversible mechanisms involved in the very complex natural oxygen carriers, e.g. the hemoglobins and hemocyanins, and as a means of separating molecular oxygen from the air. Much of the recent activity in this area has been motivated by a desire to elucidate the factors which lead to reversible 0, binding, and to understand the transport of 0, and oxidations by it in biological systems. Systematic approaches to these problems will require an understanding of the electronic nature of the coordinated 0, fragment. Reversible oxygen sorption has been observed in a number of aminoacid and dipeptide complexes of Co(H) [9]. Recently, several oxygen-carrying Correspondence to: A. Busnot, Laboratoire
de Sciences, UniversitC de Caen, Esplanade
de Chimie MinCrale et Bioinorganique, U.F.R. de la Paix, 14032 Caen Cedex, France.
444 TABLE 1 Microanalysis results ComDound
Element
Theoretical,
A
c H N Ni C H N Ni C H N Ni C H N Ni c H N Ni
32.7 6.2 25.1 8.4 33.36 5.9 24.96 8.37 32.91 5.6 25.26 8.47 33.66 4.8 25.1 8.44 32.99 6.7 24.7 8.3
B
C
D
E
%
ExReriment~,
%
33.5 5.3 25.0 8.8 33.7 4.9 25.3 8.7 33.3 5.3 25.4 9.3 33.7 5.5 25.6 9.1 33.0 5.4 25.6 8.8
chelates containing coordinating ions other than cobalt have been reported [lo], but only a limited number of publications are related to the nickel complexes. Accordingly, we have directed our initial efforts toward a study of these complexes or analogous complexes containing nitrogen labile molecules. EXPERIMENTAL
AND RESULTS
Five complexes have been prepared, involving Ni(I1) succinate, Ni(I1) maleate or Ni(I1) glutarate and imidazole (Imid). The following compounds were obtained (Table 1): (A) Ni,O,(Imid),(succinate), 4 13NH,, (B) Ni~N~(Imid~~~su~inate)~ * llNH,, (C) Ni,O,(Imid),(maleate), - 13NH,, (D) Ni*N~(Imid~~(maleate)~ - llNH,, and (E) Ni2N,(Imid),(glutarate), * 15NH,. A mixture of imidazole (2.5 X 10V2 mol) and nickel(I1) sulfate (10e2 mol) in ammoniacal medium (6M) was subjected to magnetic stirring and then filtered. The solution was kept under an 0, or a N, flow for 5 minutes and then filtered. The solution so obtained was treated with a dicarboxylic acid (2.5 x 10d2 mol) and then left for crystallization at 278 K.
445
I
300
400
500
600
700
800
900
Fig. 1. TG curves in air
E
D
C
E
A
300
400
Fig. 2. Differential
K 500
dCl0
700
thermal curves in air.
800
1000
K
K ~ NiC03
w
2NiCOs
83.6%.
WL %exp. 4.4
+ Ni(CH,-COO),
WL %th. 3.99
NiCO,
WL %exp .4.1
TG DTAfexo) 173 K
WL %th. 3.99
COO)21
WL %exp. 13.3
-
WL %th. 13.12
2[Ni(CH,
WL %exp. 19.7
WL %exp. 29.3
WL %exp. 12.4
Ni~(Imid)(suc~inate)~ WL %th. 19.4
TG 555-600 K > DTACendo) 628 K
WL %th. 29.23
a
WL %th. 13.3
Ni~N4(Imid)s(succinate)~
Ni~(Imid)s(succinate)~
WL %exp. 13.2
87.5%
WL %th. 11.2
NiO
WL %exp. 13.1
+
WL %th. 12.04
Total weight loss: theoretical 82.9%; experimental
DTAkndof 703 K
-
TG 600-774 K
DTAkndo) 400 K
m
Compound B
TG 725-831 DTAbxo) 763 K
%th. 18.13
I
WL %exp. 17.7
WL
Total weight loss: theoretical 86.02%; experimental
DTAkndo) 545 K
ZNi(CH a - COO),
WL exp. 28.5
WL %exp. 12.6
~~~~“~~~r~;
WL %th. 28.8
TG435-522K * Ni~O~tImid)~(su~inate)~
DTA&mdo) 463 K
WL %exp. 2.4
Ni*O~(Imid)~~succinate)~ WL %th. 2.45
m
WL %th. 13.4
Ni~O~{Imid)~(su~cinat~)~.2NH~
of the complexes
To 522-581K * 2[ NiO , Imid, succinate]
DTAkndo) 358 K
m
Compound A
EXHIBIT 1 Decomposition
618 K
ooc
-
l&H.2
OOC-CH
%th. 13.28
+ Ni<
WL %exp. 14.3
WL
K > NiO Imid
K )
%th. 4.03
-
+ NiCO,
WL %th. 5.25 WL %exp. 4.8
Ni,(Imid),(maleate),
WL %exp. 13.8
WL %th. 13.71
NiO
‘yOOC-fH*Imid + NIXooC-CH
82.4%.
WL %exp. 4.8
WL %th. 4.89
.,OOC-CH Nl, OOC-EH
B
82.93%; experimental
WL %exp. 3.1
WL
K > 2NiC0,
Total weight loss: theoretical
DTAho)
TG 761-831
WL %exp. 17.1
WL %th. 18.05
B
WL %exp. 12.3
WL %th. 12.27
NiP4(Imid),(maleate)6NH,
2[Ni(Imid)(maleate)]
DTAkndo) 400 K
TG 307-394
Compound D
87.2%.
TG DTAkxo) 758 K
WL %exp. 10.4
WL %th. 8.63
~~A~~~~~oKK) 2 NiC,O,
WL %th. 29.70 WL %exp. 29.9
TG 460-s57K+ Ni,(Imid),(maleate),
DTA(endo) 553 K
WL %exp. 16.6
WL %exp. 14.8
TG 557-604
K
l
DTACendo) 618 K
Ni,O,(Imid),(maleate) WL %th. 16.60
a
WL %th. 27.65
Ni204( Imid),( maleate),
WL %exp. 27.7
~~~~U~~~~~~~o ;
WL %th. 14.72
Ni,O,(Imid),(maleate)sNH,
Total weight loss: theoretical 85.96%; experimental
DTAho)
TG591-728
DTA(endo) 343 K
TG 307-386 K ,
Compound (C)
+ Ni<
OOC-
85.8%.
Ni< OOC-COOH
OOC-(CH,),-COOH
%th. 14.38
WL %exp. 14.5
WL
Total weight loss: theoretical 86.65%; experimental
DTAkxo) 743K
TG 670-756 K ,
WL %exp. 10.1
+ NiCO,
DwK
>
DTAkndo) 643K
TG 596-655 K
WL %th. 10.30
NiO
+ Ni[HOOC-(CH,)-COO],
c001-1
WI_.%exp. 4.0
OOC-COOH
OOC-(CH,),-COOH
WI_.%exp. 14.5
WL %th. 14.52
OOC-COOH
(CH 213-
WL %exp. 2.2
WL %exp. 11.4
Ni(HOOC-_(CH,)3-COO),
WL %th. 2.40
WL %th. 12
WL %th. 3.95
Ni<
DTAkndo) 598K
TG 555-596K
DTAkndo) 393K
TG 311-390K
Compound E
Exhibit 1 (continued)
+ NiCO,
WL %exp. 29.1
WL %th. 28.84
449
Thermal studies
Additional studies were carried out by thermogravimetry to confirm the molecular formulae. The measurements were performed in air over the temperature range 293-1293 K at a heating rate of 10 K min-’ using a SETARAM T.G.85 microbalance. The differential thermal analyses were performed on a micro A.T.D. M4 using a heating rate of 4 K min-‘. Thermoanalytical diagrams for the complexes are shown in Figs. 1 and 2. The general scheme of decomposition of the different complexes is summarized in the mechanisms shown in Exhibit 1 (WL = weight loss). Often the final stage of the decomposition forms the nickel carbonate or a mixture of nickel oxide with nickel carbonate. Diffuse reflectance spectra
Diffuse reflectance spectra were recorded at room temperature for all compounds on a Beckman UV 5240 spectrophotometer over the range 40000-4000 cm-r. Kodak white reflectance standard was used as a reference and for the dilution of nickel samples (10% by weight of nickel samples). In the near IR region, sharp peaks of weak intensity correspond to harmonics and combination bands of fundamental vibrations in the ligands. These bands are very difficult to assign. Two types of spectra have been recorded and are shown in Fig. 3. The electronic transitions observed and calculated for the different compounds are in Table 2.
4
14
Fig. 3. Reflectance spectra.
24
34
450 TABLE 2 Electronic transitions (cm-‘) Transition
observed and calculated for the different complexes Compound A
B
C
D
E
exp.
3A,,(F) -, 3T2,(F)
talc.
10691 10614
10767 10511
10806 10702
10682 10508
10737 10603
Shoulder 3A,,(F) --) E,
exp. talc.
13443 13554
13473 13340
13398 13929
13234 13628
13368 13135
3T,,(F) -, ‘T,,(P)
exp. talc.
16571 17187
16631 17156
16519 17017
16357 17273
16556 16752
‘&,(F) + 3T,,(F)
exp. talc.
17684 17413
17586 17161
17283 17356
17523 17240
17646 17249
3A,,(F> -, ‘T,,(P)
exp. talc.
23849 22535
23624 22470
23774 23273
24090 22736
23789 22074
v: 3A,(F) -3T,,(P)
exp. talc.
27914 * 27801
27458 27240
27582 * 27719
27393 27438
27232 26942
v: 3A,@) --) ‘T,,(G)
exp. talc.
27834 * 27667
28510 28488
27724 * 27781
27741 * 27305
3A,(F) + ‘TZg
exp.
35954
34751 35954
36030
35607
34600
3A2g(F) -, ’ E,
talc.
34747
34407 34821
36000
35077
33944
Vl
r
v3-v1
Shoulder
4
1136.2
1134.0
1096.3
1122.4
1141.0
B
767.5
760
798.4
771.7
743.8
The electronic spectra of all the complexes show a vj band in the region near 27000 cm-’ due to the 3A,(F) +3T1, (P or G) transition, a V~ band around 17000 cm-’ due to the 3A,,(F) +3T,,(F) transition and a vr band around 10500 cm-’ due to the 3Azg(F) +3T2,(F) transition. Though this assignment seems to be the most reasonable one, it does not account for the weak shoulder at around 13000 cm-‘, which appears to be due to a spin forbidden transition. It is possible that the ligand field in this complex is distorted from true octahedral symmetry and that the low symmetry component splits the 3A2g(F) d3T2,(F> transition giving the spin allowed band 3A2g(F) + ‘E,(lD). For octahedral nickel(H) complexes where the v2 and v3 bands were observed the Racah parameters B can be deduced. D9 and B were found by using the following equations [ll] 340 D4’- 18(V, + V3)Dq + V2Y3= 0 and v3 +
B=
v.2 -
15
30 o9
451
A,, is, of course, always the energy of the first transition for a d* ion; the value of A,/B [12] leads to the position of the different transitions. The values of the predicted transitions appear to be in good agreement with the observed values (Table 2). It seems that the octahedral environment is not affected by the carboxylic acid or by oxygen or nitrogen molecules. REFERENCES 1 R.G. Wilkins, Uptake of oxygen by cobalt(B) complexes in solutions, Adv. Chem. Ser., 100 (1971) 111. 2 J.S. Valentine, The dioxygen ligand in mononuclear group VIII transition metal complexes, Chem. Rev., 73 (1973) 235. 3 Yu.1. Bratushko and K.B. Yatsimirskii, Coordination compounds of 3d transition metals with molecular oxygen (collected papers), Usp. Khim. Koord. Soedin., (1975) 7. 4 A.V. Savitskii and V.I. Nelyubin, The activation of molecular oxygen with transition metal complexes, Usp. Khim., 44 (1975) 214; Russ. Chem. Rev. (Engl. Transl.), 44 (1975) 5 ;:P. Collman, Synthetic models for the oxygen-binding hemoproteins, Chem. Rev., 10 (1977) 265. 6 G. McLendon and A.E. Martell, Inorganic oxygen carriers as models for biological systems, Coord. Chem. Rev., 19 (1976) 1. 7 L. Vaska, Dioxygen metal complexes, Act. Chem. Res., 9 (1976) 175. 8 Yu.1. Bratushko and N.G. Mel’nikova, Preparation and properties of aminoacid-imidazole complexes of cobalt with molecular oxygen, Russ. J. Inorg. Chem. (Engl. Transl.), 26(11) (1981) 1607. 9 D. Burk, J.Z. Hearon, L. Caroline and A.L. Schade, J. Biol. Chem., 165 (1946) 723; E.C. Niederhoffer, J.T. Timmons and A.E. Martell, Chem. Rev., 84 (1984) 137. 10 S. Sakaki, K. Morokuma and K. Ohkubo, Ab initio MO study of the coordination modes and bonding nature of Rh*-N, complexes, J. Am. Chem. Sot., 107 (1985) 2686. 11 A.E. Underhill and D.E. Billing, Calculations of the Racah parameter B for nickel(B) and cobalt(B) compounds, Nature (London), 5038 (1966) 835. 12 Y. Tanabe and S. Sugano, J. Phys. Sot. Jpn., 9 (1954) 753; 9 (1954) 766.
443
Synthetic reversible oxygen- or nitrogen-carrying of nickel( II)
chelates
A. Busnot, J.F. IX Querler and J. Yazbeck Laboratoire de Chimie Minirale et Bioinorganique, U.F.R. de Sciences, Universite’ de Caen, Esplanade de la Pair, 14032 Caen Cedex (France)
(Received 7 July 1991)
Abstract
New oxygenated complexes of nickel(I1) with the composition Ni,O,(Imid),A;zNH, or Ni,N,(Imid),,A,, .z’NH,, where Imid represents the imidazole molecule and A the anion of succinic acid, maleic acid or glutaric acid, have been synthesized. The behavior of these salts when heated in air has been studied by thermogravimetric methods and it has been established that in all cases the product of the decomposition is the oxide or the carbonate. Diffuse reflectance spectra are presented. Calculated electronic transitions are in good agreement with those observed. It seems that the nickel ions are in an octahedral environment. INTRODUCTION
Coordination compounds of transition metals with molecular oxygen are currently being studied [l-S]. In a number of cases, these coordination compounds can activate molecular oxygen and catalyse oxidations. Synthetic reversible oxygen-carrying chelates, i.e., chelates that can take up and release molecular oxygen reversibly, have been of interest as model compounds in the study of the reversible mechanisms involved in the very complex natural oxygen carriers, e.g. the hemoglobins and hemocyanins, and as a means of separating molecular oxygen from the air. Much of the recent activity in this area has been motivated by a desire to elucidate the factors which lead to reversible 0, binding, and to understand the transport of 0, and oxidations by it in biological systems. Systematic approaches to these problems will require an understanding of the electronic nature of the coordinated 0, fragment. Reversible oxygen sorption has been observed in a number of aminoacid and dipeptide complexes of Co(H) [9]. Recently, several oxygen-carrying Correspondence to: A. Busnot, Laboratoire
de Sciences, UniversitC de Caen, Esplanade
de Chimie MinCrale et Bioinorganique, U.F.R. de la Paix, 14032 Caen Cedex, France.
444 TABLE 1 Microanalysis results ComDound
Element
Theoretical,
A
c H N Ni C H N Ni C H N Ni C H N Ni c H N Ni
32.7 6.2 25.1 8.4 33.36 5.9 24.96 8.37 32.91 5.6 25.26 8.47 33.66 4.8 25.1 8.44 32.99 6.7 24.7 8.3
B
C
D
E
%
ExReriment~,
%
33.5 5.3 25.0 8.8 33.7 4.9 25.3 8.7 33.3 5.3 25.4 9.3 33.7 5.5 25.6 9.1 33.0 5.4 25.6 8.8
chelates containing coordinating ions other than cobalt have been reported [lo], but only a limited number of publications are related to the nickel complexes. Accordingly, we have directed our initial efforts toward a study of these complexes or analogous complexes containing nitrogen labile molecules. EXPERIMENTAL
AND RESULTS
Five complexes have been prepared, involving Ni(I1) succinate, Ni(I1) maleate or Ni(I1) glutarate and imidazole (Imid). The following compounds were obtained (Table 1): (A) Ni,O,(Imid),(succinate), 4 13NH,, (B) Ni~N~(Imid~~~su~inate)~ * llNH,, (C) Ni,O,(Imid),(maleate), - 13NH,, (D) Ni*N~(Imid~~(maleate)~ - llNH,, and (E) Ni2N,(Imid),(glutarate), * 15NH,. A mixture of imidazole (2.5 X 10V2 mol) and nickel(I1) sulfate (10e2 mol) in ammoniacal medium (6M) was subjected to magnetic stirring and then filtered. The solution was kept under an 0, or a N, flow for 5 minutes and then filtered. The solution so obtained was treated with a dicarboxylic acid (2.5 x 10d2 mol) and then left for crystallization at 278 K.
445
I
300
400
500
600
700
800
900
Fig. 1. TG curves in air
E
D
C
E
A
300
400
Fig. 2. Differential
K 500
dCl0
700
thermal curves in air.
800
1000
K
K ~ NiC03
w
2NiCOs
83.6%.
WL %exp. 4.4
+ Ni(CH,-COO),
WL %th. 3.99
NiCO,
WL %exp .4.1
TG DTAfexo) 173 K
WL %th. 3.99
COO)21
WL %exp. 13.3
-
WL %th. 13.12
2[Ni(CH,
WL %exp. 19.7
WL %exp. 29.3
WL %exp. 12.4
Ni~(Imid)(suc~inate)~ WL %th. 19.4
TG 555-600 K > DTACendo) 628 K
WL %th. 29.23
a
WL %th. 13.3
Ni~N4(Imid)s(succinate)~
Ni~(Imid)s(succinate)~
WL %exp. 13.2
87.5%
WL %th. 11.2
NiO
WL %exp. 13.1
+
WL %th. 12.04
Total weight loss: theoretical 82.9%; experimental
DTAkndof 703 K
-
TG 600-774 K
DTAkndo) 400 K
m
Compound B
TG 725-831 DTAbxo) 763 K
%th. 18.13
I
WL %exp. 17.7
WL
Total weight loss: theoretical 86.02%; experimental
DTAkndo) 545 K
ZNi(CH a - COO),
WL exp. 28.5
WL %exp. 12.6
~~~~“~~~r~;
WL %th. 28.8
TG435-522K * Ni~O~tImid)~(su~inate)~
DTA&mdo) 463 K
WL %exp. 2.4
Ni*O~(Imid)~~succinate)~ WL %th. 2.45
m
WL %th. 13.4
Ni~O~{Imid)~(su~cinat~)~.2NH~
of the complexes
To 522-581K * 2[ NiO , Imid, succinate]
DTAkndo) 358 K
m
Compound A
EXHIBIT 1 Decomposition
618 K
ooc
-
l&H.2
OOC-CH
%th. 13.28
+ Ni<
WL %exp. 14.3
WL
K > NiO Imid
K )
%th. 4.03
-
+ NiCO,
WL %th. 5.25 WL %exp. 4.8
Ni,(Imid),(maleate),
WL %exp. 13.8
WL %th. 13.71
NiO
‘yOOC-fH*Imid + NIXooC-CH
82.4%.
WL %exp. 4.8
WL %th. 4.89
.,OOC-CH Nl, OOC-EH
B
82.93%; experimental
WL %exp. 3.1
WL
K > 2NiC0,
Total weight loss: theoretical
DTAho)
TG 761-831
WL %exp. 17.1
WL %th. 18.05
B
WL %exp. 12.3
WL %th. 12.27
NiP4(Imid),(maleate)6NH,
2[Ni(Imid)(maleate)]
DTAkndo) 400 K
TG 307-394
Compound D
87.2%.
TG DTAkxo) 758 K
WL %exp. 10.4
WL %th. 8.63
~~A~~~~~oKK) 2 NiC,O,
WL %th. 29.70 WL %exp. 29.9
TG 460-s57K+ Ni,(Imid),(maleate),
DTA(endo) 553 K
WL %exp. 16.6
WL %exp. 14.8
TG 557-604
K
l
DTACendo) 618 K
Ni,O,(Imid),(maleate) WL %th. 16.60
a
WL %th. 27.65
Ni204( Imid),( maleate),
WL %exp. 27.7
~~~~U~~~~~~~o ;
WL %th. 14.72
Ni,O,(Imid),(maleate)sNH,
Total weight loss: theoretical 85.96%; experimental
DTAho)
TG591-728
DTA(endo) 343 K
TG 307-386 K ,
Compound (C)
+ Ni<
OOC-
85.8%.
Ni< OOC-COOH
OOC-(CH,),-COOH
%th. 14.38
WL %exp. 14.5
WL
Total weight loss: theoretical 86.65%; experimental
DTAkxo) 743K
TG 670-756 K ,
WL %exp. 10.1
+ NiCO,
DwK
>
DTAkndo) 643K
TG 596-655 K
WL %th. 10.30
NiO
+ Ni[HOOC-(CH,)-COO],
c001-1
WI_.%exp. 4.0
OOC-COOH
OOC-(CH,),-COOH
WI_.%exp. 14.5
WL %th. 14.52
OOC-COOH
(CH 213-
WL %exp. 2.2
WL %exp. 11.4
Ni(HOOC-_(CH,)3-COO),
WL %th. 2.40
WL %th. 12
WL %th. 3.95
Ni<
DTAkndo) 598K
TG 555-596K
DTAkndo) 393K
TG 311-390K
Compound E
Exhibit 1 (continued)
+ NiCO,
WL %exp. 29.1
WL %th. 28.84
449
Thermal studies
Additional studies were carried out by thermogravimetry to confirm the molecular formulae. The measurements were performed in air over the temperature range 293-1293 K at a heating rate of 10 K min-’ using a SETARAM T.G.85 microbalance. The differential thermal analyses were performed on a micro A.T.D. M4 using a heating rate of 4 K min-‘. Thermoanalytical diagrams for the complexes are shown in Figs. 1 and 2. The general scheme of decomposition of the different complexes is summarized in the mechanisms shown in Exhibit 1 (WL = weight loss). Often the final stage of the decomposition forms the nickel carbonate or a mixture of nickel oxide with nickel carbonate. Diffuse reflectance spectra
Diffuse reflectance spectra were recorded at room temperature for all compounds on a Beckman UV 5240 spectrophotometer over the range 40000-4000 cm-r. Kodak white reflectance standard was used as a reference and for the dilution of nickel samples (10% by weight of nickel samples). In the near IR region, sharp peaks of weak intensity correspond to harmonics and combination bands of fundamental vibrations in the ligands. These bands are very difficult to assign. Two types of spectra have been recorded and are shown in Fig. 3. The electronic transitions observed and calculated for the different compounds are in Table 2.
4
14
Fig. 3. Reflectance spectra.
24
34
450 TABLE 2 Electronic transitions (cm-‘) Transition
observed and calculated for the different complexes Compound A
B
C
D
E
exp.
3A,,(F) -, 3T2,(F)
talc.
10691 10614
10767 10511
10806 10702
10682 10508
10737 10603
Shoulder 3A,,(F) --) E,
exp. talc.
13443 13554
13473 13340
13398 13929
13234 13628
13368 13135
3T,,(F) -, ‘T,,(P)
exp. talc.
16571 17187
16631 17156
16519 17017
16357 17273
16556 16752
‘&,(F) + 3T,,(F)
exp. talc.
17684 17413
17586 17161
17283 17356
17523 17240
17646 17249
3A,,(F> -, ‘T,,(P)
exp. talc.
23849 22535
23624 22470
23774 23273
24090 22736
23789 22074
v: 3A,(F) -3T,,(P)
exp. talc.
27914 * 27801
27458 27240
27582 * 27719
27393 27438
27232 26942
v: 3A,@) --) ‘T,,(G)
exp. talc.
27834 * 27667
28510 28488
27724 * 27781
27741 * 27305
3A,(F) + ‘TZg
exp.
35954
34751 35954
36030
35607
34600
3A2g(F) -, ’ E,
talc.
34747
34407 34821
36000
35077
33944
Vl
r
v3-v1
Shoulder
4
1136.2
1134.0
1096.3
1122.4
1141.0
B
767.5
760
798.4
771.7
743.8
The electronic spectra of all the complexes show a vj band in the region near 27000 cm-’ due to the 3A,(F) +3T1, (P or G) transition, a V~ band around 17000 cm-’ due to the 3A,,(F) +3T,,(F) transition and a vr band around 10500 cm-’ due to the 3Azg(F) +3T2,(F) transition. Though this assignment seems to be the most reasonable one, it does not account for the weak shoulder at around 13000 cm-‘, which appears to be due to a spin forbidden transition. It is possible that the ligand field in this complex is distorted from true octahedral symmetry and that the low symmetry component splits the 3A2g(F) d3T2,(F> transition giving the spin allowed band 3A2g(F) + ‘E,(lD). For octahedral nickel(H) complexes where the v2 and v3 bands were observed the Racah parameters B can be deduced. D9 and B were found by using the following equations [ll] 340 D4’- 18(V, + V3)Dq + V2Y3= 0 and v3 +
B=
v.2 -
15
30 o9
451
A,, is, of course, always the energy of the first transition for a d* ion; the value of A,/B [12] leads to the position of the different transitions. The values of the predicted transitions appear to be in good agreement with the observed values (Table 2). It seems that the octahedral environment is not affected by the carboxylic acid or by oxygen or nitrogen molecules. REFERENCES 1 R.G. Wilkins, Uptake of oxygen by cobalt(B) complexes in solutions, Adv. Chem. Ser., 100 (1971) 111. 2 J.S. Valentine, The dioxygen ligand in mononuclear group VIII transition metal complexes, Chem. Rev., 73 (1973) 235. 3 Yu.1. Bratushko and K.B. Yatsimirskii, Coordination compounds of 3d transition metals with molecular oxygen (collected papers), Usp. Khim. Koord. Soedin., (1975) 7. 4 A.V. Savitskii and V.I. Nelyubin, The activation of molecular oxygen with transition metal complexes, Usp. Khim., 44 (1975) 214; Russ. Chem. Rev. (Engl. Transl.), 44 (1975) 5 ;:P. Collman, Synthetic models for the oxygen-binding hemoproteins, Chem. Rev., 10 (1977) 265. 6 G. McLendon and A.E. Martell, Inorganic oxygen carriers as models for biological systems, Coord. Chem. Rev., 19 (1976) 1. 7 L. Vaska, Dioxygen metal complexes, Act. Chem. Res., 9 (1976) 175. 8 Yu.1. Bratushko and N.G. Mel’nikova, Preparation and properties of aminoacid-imidazole complexes of cobalt with molecular oxygen, Russ. J. Inorg. Chem. (Engl. Transl.), 26(11) (1981) 1607. 9 D. Burk, J.Z. Hearon, L. Caroline and A.L. Schade, J. Biol. Chem., 165 (1946) 723; E.C. Niederhoffer, J.T. Timmons and A.E. Martell, Chem. Rev., 84 (1984) 137. 10 S. Sakaki, K. Morokuma and K. Ohkubo, Ab initio MO study of the coordination modes and bonding nature of Rh*-N, complexes, J. Am. Chem. Sot., 107 (1985) 2686. 11 A.E. Underhill and D.E. Billing, Calculations of the Racah parameter B for nickel(B) and cobalt(B) compounds, Nature (London), 5038 (1966) 835. 12 Y. Tanabe and S. Sugano, J. Phys. Sot. Jpn., 9 (1954) 753; 9 (1954) 766.