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Manganese(III) heterochelates involving quadridented Schiff bases
J. inorg,nucl.Chem.,1975,VoL37. pp. 695~98. PergamonPress. Printedin GreatBritain
MANGANESE(Ill) HETEROCHELATES INVOLVING QUADRIDENTED SCHIFF BASES K. DEY* and K. C. RAY Department of Chemistry, University of Kalyani, Kalyani, Nadia, West Bengal, India
(First received 11 March 1974; in revised form 19 June 1974) Ahstract--Manganese(III) heterochelates of the types: 6) [Mn(Lig)(L-L)]nHaO(where, Lig=N,N'-ethylene bis(salicylideneiminato) dianion, or N,N'-trimethylene bis(salicylideneiminato) dianion; L - L = acetylacetone or salicylaldehyde anion; n = 0 or 2) and (ii) [Mn(Lig)(L-L)] C104 (where, L - L = ethylenediamine or dipyridyl) have been isolated either by the reactions of bis(acetylacetonato) manganese(II) or bis(salicylaldehydato) manganese(II) with preformed Schiff bases (type-i) or by the reaction of Mn(Lig) with "L-L" (type-ii) in absolute alcohol in the presence of oxygen under reflux. I.R. and electronic absorption spectra are reported. The first type of complex are non-conducting in DMSO, while the second are 1 : 1 electrolytes in ethanol. The magnetic moments of the solid complexes at room temperature range from 4.70-5.00 B.M., which show that the complexes are spin-free with no exchange or superexchange interactions. A non-planar conformation of the quadridented ligands in the manganese(III) heterochelates has been tentatively proposed.
INTRODUCTION DURING recent years there has been an increased interest in Schiff base complexes of manganese(III)[1]. We have been studying the preparation and properties of trivalent metal chelates of Schiff bases[l-9], and have isolated some manganese(III) heterochelates involving dibasic quadridentate Schiff bases (=Lig-Ha) and neutral or monobasic bidentate ligands ( = L - L ) of the types: (a) [Mn(Lig)(L-L)] nH~O (where, n = 2 or 0), and (b) [Mn(Lig)(L-L)]CIO4. This paper describes our preliminary results. There are very few reports on the heterochelates of manganese(III)[10-12]. EXPERIMENTAL Manganese(IIl) acetate dihydrate was prepared by a previously published method[13]. The molar couductances, electronic spectra and magnetic susceptibilities were measured and elemental analyses were performed as described previously [3].
Preparation of manganese(Ill) heterochelates N,N'-Ethylene bis(salicylideneiminato) acetylacetonato manganese(III) dihydrate, [Mn(BSEN)(acac)] 2H20, (I). Bis(acetylacetonato) manganese(II) dihydrate, Mn(acac)2. 2H:O (0.001 mole) and the Schiff base BSEN-Ha (0"001 mole) were taken in 100ml of absolute ethanol. Air was then drawn through the mixture for about 6 hr, followed by heating on a water-bath for about 1/2 hr. The mixture was then filtered. The volume of the brown filtrate was reduced to one third and on adding ether, it gave a brown gummy compound. This gummy material was washed several times with ether and then triturated with the same solvent to yield a brown crystalline compound. The compound is soluble in coordinating solvents (e.g. dimethylsulfoxide, dimethylformamide, pyridine etc.), insoluble in carbon-tetrachloride, benzene, and ether. It is also sparingly soluble in ethanol and methanol. It is non-conducting in DMSO. *All correspondence to this author. 695
N,N'- Trimethylenebis (salicylideneiminato ) acetylacetonato manganese(III), [Mn(BSTN)(acac)], (H). The same method was used to prepare brown [Mn(BSTN)(acac)], except that BSTN-H2 was used in place of BSEN-Ha. The compound is soluble in coordinating solvents (e.g. DMF, DMSO, py etc.), sparingly soluble in water, but insoluble in chloroform, carbon-tetrachloride, ether and benzene. It is non-conducting in DMSO.
N,N'-Ethylene bis (salicylideneiminato ) salicylaldehydato manganese(Ill), [Mn(BSEN)(sal)], (III). Bis(salicylaldehydato) manganese(II) dihydrate, Mn(sal)2, 2H20 (0.005 mole) was taken in 50 ml of ethanol. To this was added BSEN-H~ (0.005 mole) in 50 ml of ethanol. Air was bubbled through the mixture for about 6 hr, followed by refluxing on water-bath for [ hr. The reddish brown compound, thus obtained, was filtered and washed with an ether-alcohol mixture (50:50) and finally with ether. The compound was dried in a desiccator over fused calcium chloride. The compound is soluble in coordinating solvents, sparingly soluble in water, ethanol and methanol and insoluble in carbon-tetrachloride, ether and benzene. It is non-conducting in DMSO.
N,N'- Trimethylenebis( salicylideneiminato ) salicylaldehydato manganese(III), [Mn(BSTN)(sal)], (IV). The method used to isolate the compound fill) gave this brown compound [Mn(BSTN)(sal)]. It is soluble in coordinating solvents, sparingly soluble in water, ethanol and methanol, but insoluble in carbon-tetrachloride, ether, and benzene. It is non-conducting in DMSO.
N,N'-Ethylenebis(salicylideneiminato ) ethylenediamine manganese(Ill) perchlorite, [Mn(BSEN)(en)] C10,, (V). To a hot solution of N,N'-ethylenebis(salicylideneiminato) manganese(II) (0.005 mole) in 50 ml of ethanol was added an ethanolic (50 ml) solution of ethylenediamine (0-005 mole). The mixture was refluxed for half an hour and filtered while hot. The brown filtrate was treated with a stoichiometric amount of a methanotic solution of sodium perchlorate and the volume was reduced to half. On standing a brown crystalline compound separated, it was filtered, washed with ethanol and dried in a desiccator over fused calcium chloride.
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It is soluble in water, ethanol and coordinating solvents, but insoluble in ether, benzene, carbon tetrachloride. The molar conductance value (Au) of an 1'5 × 10-3 M ethanol solution was found to be 72 fF 1cm2 mole-~ at 28°C, showingthe presence of a 1 : 1 electrolyte in this solvent.
N,N'-Ethylenebis(salicylideneiminato) bipyridino manganese(llI) perchlorate, [Mn(BSEN)(bipy)]CIO,,(VI). This brown compound was isolated by the method described for (V), using dipyridyl instead of ethylenediamine. It is soluble in water, ethanol, and coordinating solvents but insoluble in carbon tetrachloride, ether and benzene. The ~.,~ value of an 1.8× 10-3M ethanol solution was found to be 98 ohm-~ cm2 mole-' at 28°C, showing the presence of an 1:1 electrolyte in this solvent. RESULTS AND DISCUSSION When bis(acetylacetonato) manganese(II) or bis(salicylaldehydato) manganese(II) was reacted with preformed quadridentated Schiff bases in absolute alcohol in the presence of oxygen, heterochelates of the type [Mn(Lig)(L-L)]nH20 (where, Lig=dianions of the Schiff bases BSEN-H2 and BSTN-H2; L - L ---anion of acetylacetone and salicyaldehyde) were isolated. The reaction of N,N'-ethylene bis(salicylidineiminato) manganesed(II) with ethylenedianine or dipyridyl in air produced the heterochelates [Mn(BSEN)(en)] ÷ or [Mn(BSEN)(dipy)]+, which were isolated as perchlorates. The heterochelates are all paramagnetic and show magnetic moment values in the range 5.00-4.70 B.M. at room temperature (Table 1) indicating the presence of tervalent manganese. These values show the absence of exchange or superexchange interactions. The complexes(I)-(IV) are found to be virtually nonconducting in DMSO, while compounds (V) and (VI) show molar conductances 72.00 and 98.00 ohm-' cm -2
mole-' respectively in dry methanol, which demonstrates some dissociation in the medium. The electronic absorption bands along with their log E values are given in Table 2. Usually high-spin manganese(Ill) complexes with octahedral geometry are expected to give[14] one charge-transfer band around 25,000 cm -1 (log E = 3.5) and a spin-allowed d-d transition band, ~Eg--,~T:g around 20,000cm -1 (log e =2.5). The electronic absorption spectra of the present manganese(III) heterochelates, measured in the region 14,000-15,000 cm-', consist of several intense bands and shoulders. The positions of the bands can be roughly divided into two areas which lie between 14,000-15,000 cm -1 and 16,000-25,000 cm -1. The bands at high wave numbers are seen as shoulders on intense charge-transfer absorptions. The absorption in the visible region 16,000-25,000 cm -~ can be assigned to the 5E~ 5T2~ transition, though there is the possibility that the bands at -25,000 cm -1 may be of charge-transfer origin. The splitting of the bands is most likely due to the John-Teller distortion as observed in many complexes of manganese(III)[1, 15]. Despite much work on manganese(III) chelates[l, 15], difficulties have arisen in the assignment of the bands in the near-infrared region. High-spin manganese(III) complexes always show at least one absorption in the region 8000-13,000cm -~. The relationship of this band to the structure of the complexes has not been clarified. We also observe a band in the region 14,000-15,000cm-~. However, such a band has recently been assigned as a low-energy charge-transfer transition in such chelates[15]. The numerical data on the i.r. spectra of the manganese(III) heterochelates are recorded in Table 3. For the complexes [MN(BSEN](acac)]2H:O, (I) and
Table 1. Elemental analyses and magnetic moments of manganese(Ill)heterochelates Found %
Cald. % /zo.(B.M.)
Complex* [Mn(BSEN)(acac)].2H20, (I) [Mn(BSTN)(acac)],(II) [Mn(BSEN)(sal)],(III) [Mn(BSTN)(sal)],(IV) [Mn(BSEN)(en)]C104,(V) [Mn(BSEN)(dipy)]CIO,, (VI)
C
H
N
Mn
C
I4
N
Mn
(roomtemp.)
55.82 61.02 62.58 62.88 45.22 53.48
5.20 5.45 4.50 3.98 5.02 4.96
5.81 7.00 6.03 5.88 12.00 10.00
12.01 13-02 12.00 11.92 10.96 10.08
55.26 60.82 62.44 63' 16 44.96 54.08
5.48 5.30 4.30 4.16 4.58 3.82
6.14 6.45 6.33 6.14 11.66 9.71
12.06 12.68 12.46 12.06 11.45 9.53
5.00 4.82 4.70 4.82 4.90 5.00
*BSEN = N,N'-ethylenebis(salicylideneiminato) dianion. BSTN= N,N'-trimethylenebis(salicylidineiminato) dianion, acac= acetylacetonate anion, en = ethylenediamine, dipy = dipyridyl. Table 2. Electronic spectral data of manganese(III)-heterochelates Complex [Mn(BSEN)(acac)]2H20, (I) [Mn(BSTN)(acac)],(II) [Mn(BSEN)(sal)],(III) [Mn(BSTN)(sal)],(IV) [Mn(BSEN)(en)]C10,, (V)
Solvent MeOH MeOH DMSO DMSO EtOH
Vmaxin cm-' (log Emo~) 40,000(4.3); 35,700(4.2); 24,800(sh); 20,600(sh); 16,500(2.4), 41,600(sh); 35,700(4.1); 32,700(sh); 20,400(2.7); 19,600(sh); 18,000(sh). 25,000(3.8); 15,600(sh); 14,200(sh). 30,O00(sh); 17,850(2.6); 16,000(sh); 14,500(sh). 40,450(4.6); 41.666(4.6); 36,000(4.2); 32,500(sh); 29,400(sh); 27,000(sh); 17,000(sh); 15,400(sh).
697
Manganese(Ill)heterochelates Table 3. Infrared spectra (KBr phase) of some manganese(III)heterochelates [Mn(BSEN)(acac)]2H20, (I) lMn(BSTN)(acac)],(II) [Mn(BSEN)(sal)],(III)
[Mn(BSTN)(sal)],(lV)
[Mn(BSEN)(en)]CIO., (V) [Mn(BSEN)(dipy)]CIO4,(VI)
3500(m); 1675(sh); 1650(vs); 1610-1550(s,doublets); 1500-1450(s,doublets); 1395(sh); 1345(s); 1300(vs); 1200(m); 1165(m); 1145(m); 1095(vs); 1050-1040 (w, dpibfiets); 910(m); 860-840(w,doublets); 810(m); 765(s). 3550(s); 3000(sh); 1620-1530(s,doublet); 1498(sh); 1450(vs); 1300(vs); 1210 (Br,); l150(m); 1135(m);910(m); 855(br,w); 810(m); 765(s). 3070-3000(w,triplets); 1650(sh); 1640(vs); 1610(s); 1550(m); 1475(m,doublet); 1410(vw); 1400(m); 1340(m); 1290(m); 1250(m); 1205(w); l190(m); l150(s); l130(m); 1095(w); 1050(w);995(w); 980--950(w,triplet); 910(m); 865(m,doublet): 825(m); 810(m); 798(sh); 775(m); 765(vs). 3060-2900(w,triplet); 1650(vs); 1620(s); 1575(s); 1500(s); 1498(vs); 1460(vs); 1400(m); 1350(sh); 1315(vs); 1210(m); ll701s); l140(m); l ll5(sh); 1075 (w, doublet); 1040(w);980(w); 940(sh): 910(s); 860(w,doublet); 820(sh); 810(m); 795(sh); 762(s); 745(m). 3040(m,br); 1645(vs); 1615(sh); 1550(s); 1495(m); 1400(m); 1340(w); 1300(s); 1210(w); 1180-1080(vs,br); 980(w,br); 910(m); 860(w,br); 810(m); 760(m,doublets). 3050-2900(w,triplets); 1655(sh); 1650(vs); 1620(vs); 1560(vs); 1480(s); 1450(vs); 1425(sh); 1400(sh); 1350(sh); 1340(s); 1305(vs); 1280(s); 1255(w,doublet); 1245(sh); 1225(sh); 1210(s); 1175(m); l150-1060(br,vs); 1050(s); 1040(sh); 1025(sh); 980(m,doublet): 975(m); 945(w); 910(m): 810(s); 800(sh); 780(s); 775(m); 765(sh); 755(vs).
[Mn(BSTN)(acac)], (II), the chelate oxygen-bonded acetylacetonate anion is shown in the vibrational spectral data[16,17] where we found v c ~ at 1550cm -~ and 1530 cm ~' respectively for complexes (I) and (II), while vc'-"cis observed at about 1500 cm ' for both chelates. The wc=o for the carbon-bonded acetylacetone occurs above 1650 cm ~[18]. Despite the added complexities due to the presence of C=N and C=C stretching modes of the present Schiff bases, the vibrational spectral data of (I) and (II) clearly show the presence of the oxygen-bonded chelating acetylacetonate anion. Infrared spectra of quandridentate Schiff bases and their metallic complexes have been discussed thoroughly[19, 21]. The present quadridentate Schiff bases have weak to medium (but broad) bands around 2700 cm -~ assignable to intremolecular hydrogen bonded OH groups, while vc-N appeared around 1630 c m ~ in the free ligands. The broad and weak band due to vo. disappears in the complexes indicating the metal-oxygen (phenolic) bond formation in the present mixed ligand complexes of manganese(III). The vc=N in the complexes was observed around 1610-1620cm-' indicating the coordination of imine nitrogen[22]. The phenolic C-O in the Schiff bases is observed around 1280 cm -t, which is shifted to the region 1300-1350 cm-' in the mixed chelates [22]. Characteristic bands for water molecule for complex (I) are observed at 3500 cm 1 assignable to VOHand at -1650 cm-' assignable to 8oH [23]. The i.r. spectral data of complexes(V) and (VI) show a strong and broad band in the range 1060-1150 cm L assignable to the v3 mode of C104 ion vibration (in Td symmetry) [24-26]. This band demonstrates the presence ionic perchlorate in these two chelates. The N-H stretching frequency in complex (V) occurs at 3040 c m t, demonstrating the coordinated NH2 group[27, 28]. From the above observations it may be concluded that the quadridentate Schiff bases in the present manganese(III) heterochelates, [Mn(Lig)(L-L)] have been rearranged from a planar to a twisted conformation by the
displacement of only one oxygen atom from the equatorial plane of the planar isomer and that the bidentate ligands are in cis-position in the above mentioned mixed chelates. Analogous non-planar geometry of the dibasic quadridentate Schiff base BSEN in heteroch~lates of the type [Co(BSEN)(L-L)] nH20 has been confirmed by X-ray crystallographic and p.m.r. studies [1,29]. Acknowledgement--The authors are thankful to Dr. S. N. Poddar of Indian Association for the Cultivation of Science, Calcutta-32 for mull spectra, Prof. N. N. Ghosh, Calcutta University for allowingthem to use the Gouy balance, and to U.G.C. (India) for financial assistance to one of them (K.C.R.). REFERENCES
1. K. Dey, J. scient, ind. Res. In Press and references cited therein; W. Levason and C, A. McAuliffe Coord. chem. Rev. 7, 353 (1972) and references cited therein. 2. K. Dey, Z anorg, allg. chem. 376, 209 (1970). 3. K. Dey, R. L. De and K. C. Ray, Indian Y. Chem. 10, 864 (1972). 4. K. Dey and K. C. Ray, J. Indian chem. Soc. 50, 66 (1973). 5. K. Dey and R. L. De, Z. anorg, aUg. Chem. 402, 120(1973). 6. K. Dey and R. L. De, J. inorg, nucl. Chem. In Press. 7. K. Dey and K. C. Ray, J. Indian chem. Soc. In Press. 8. K. Dey and R. L. De, 3". Indian chem. Soc. In Press. 9. K. Dey and K. C. Ray, Inorg. Chim. Acta. Communicated. 10. M. M. Ray, J. N. Adhya, D. Biswas and S. N. Poddar, Aust. J. Chem. 19, 881 (1%6). 11. M. M. Ray, S. N. Adhya, N. G. Poddar and S. N. Poddar, Aust. 3. Chem. 21,801 (1%8). 12. M. Bartlett and G. J. Palenik, Chem. Comm. 416 (1970). 13. O. T. Christensen, Z. anorg, allg. Chem. 27, 325 (1901). 14. C. Furlani and A. Ciano, Analyt. Chim. 48, 286 (1958). 15. A. Vanden Bergen, K. S. Murray, M. J. O'Conner and B. O. West, Aust. J. Chem. 22, 39 (1969). 16. R. J. York, W. D. Bonds. Jr., B. P. Cotsoradis and R. D. Archer. Inorg. Chem. 8, 789 (1969). 17. L. J. Boucher and D. P. Herrington, J. inorg, nucl. Chem. 33, 4349 (1971).
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18. J. Lewis, R. F. Long and C. Oldham, J. Chem. Soc. (A) 6740 (1%5). 19. S.J. Gruber, C. M. Haris and E. Sinn, J. inorg, nucL Chem. 30, 1805 (1%8). 20. K. Ueno and A. E. Martell, J. phys. Chem. 60, 1270 (1956). 21. K. Ueno and A. E. Martell, J. phys. Chem. 59, 998 (1955). 22. J. E. Kovacic, Spectrochim. Acta 23A, 183 (1967). 23. P. C. Hewlett and L. F. Larkworthy, Y. Chem. Soc. 882 (1965). 24. K. Nakamoto, Infrared Spectra o[ Inorganic and Coordination Compounds. Wiley, New York (1%3).
25. B. J. Hathaway and A. E. Underhill, J. chem. Soc., 3091 (1%1). 26. S. Buffagni, L. M. Valarino and J. V. Quagliano, Inorg. Chem. 3, 671 (1964), 27. R. D. Archer and B. P. Costoradis, Inorg. Chem. 4, 1584 (1965). 28. E. Cara, A. Critini, A. Diaz and G. Panticelli, J. chem. Soc. Dalton. 527 (1972). 29. D. Cummins, B. M. Higson and E. D. McKenzie, J. chem. Soc. Dalton, 1359 (1973).
MANGANESE(Ill) HETEROCHELATES INVOLVING QUADRIDENTED SCHIFF BASES K. DEY* and K. C. RAY Department of Chemistry, University of Kalyani, Kalyani, Nadia, West Bengal, India
(First received 11 March 1974; in revised form 19 June 1974) Ahstract--Manganese(III) heterochelates of the types: 6) [Mn(Lig)(L-L)]nHaO(where, Lig=N,N'-ethylene bis(salicylideneiminato) dianion, or N,N'-trimethylene bis(salicylideneiminato) dianion; L - L = acetylacetone or salicylaldehyde anion; n = 0 or 2) and (ii) [Mn(Lig)(L-L)] C104 (where, L - L = ethylenediamine or dipyridyl) have been isolated either by the reactions of bis(acetylacetonato) manganese(II) or bis(salicylaldehydato) manganese(II) with preformed Schiff bases (type-i) or by the reaction of Mn(Lig) with "L-L" (type-ii) in absolute alcohol in the presence of oxygen under reflux. I.R. and electronic absorption spectra are reported. The first type of complex are non-conducting in DMSO, while the second are 1 : 1 electrolytes in ethanol. The magnetic moments of the solid complexes at room temperature range from 4.70-5.00 B.M., which show that the complexes are spin-free with no exchange or superexchange interactions. A non-planar conformation of the quadridented ligands in the manganese(III) heterochelates has been tentatively proposed.
INTRODUCTION DURING recent years there has been an increased interest in Schiff base complexes of manganese(III)[1]. We have been studying the preparation and properties of trivalent metal chelates of Schiff bases[l-9], and have isolated some manganese(III) heterochelates involving dibasic quadridentate Schiff bases (=Lig-Ha) and neutral or monobasic bidentate ligands ( = L - L ) of the types: (a) [Mn(Lig)(L-L)] nH~O (where, n = 2 or 0), and (b) [Mn(Lig)(L-L)]CIO4. This paper describes our preliminary results. There are very few reports on the heterochelates of manganese(III)[10-12]. EXPERIMENTAL Manganese(IIl) acetate dihydrate was prepared by a previously published method[13]. The molar couductances, electronic spectra and magnetic susceptibilities were measured and elemental analyses were performed as described previously [3].
Preparation of manganese(Ill) heterochelates N,N'-Ethylene bis(salicylideneiminato) acetylacetonato manganese(III) dihydrate, [Mn(BSEN)(acac)] 2H20, (I). Bis(acetylacetonato) manganese(II) dihydrate, Mn(acac)2. 2H:O (0.001 mole) and the Schiff base BSEN-Ha (0"001 mole) were taken in 100ml of absolute ethanol. Air was then drawn through the mixture for about 6 hr, followed by heating on a water-bath for about 1/2 hr. The mixture was then filtered. The volume of the brown filtrate was reduced to one third and on adding ether, it gave a brown gummy compound. This gummy material was washed several times with ether and then triturated with the same solvent to yield a brown crystalline compound. The compound is soluble in coordinating solvents (e.g. dimethylsulfoxide, dimethylformamide, pyridine etc.), insoluble in carbon-tetrachloride, benzene, and ether. It is also sparingly soluble in ethanol and methanol. It is non-conducting in DMSO. *All correspondence to this author. 695
N,N'- Trimethylenebis (salicylideneiminato ) acetylacetonato manganese(III), [Mn(BSTN)(acac)], (H). The same method was used to prepare brown [Mn(BSTN)(acac)], except that BSTN-H2 was used in place of BSEN-Ha. The compound is soluble in coordinating solvents (e.g. DMF, DMSO, py etc.), sparingly soluble in water, but insoluble in chloroform, carbon-tetrachloride, ether and benzene. It is non-conducting in DMSO.
N,N'-Ethylene bis (salicylideneiminato ) salicylaldehydato manganese(Ill), [Mn(BSEN)(sal)], (III). Bis(salicylaldehydato) manganese(II) dihydrate, Mn(sal)2, 2H20 (0.005 mole) was taken in 50 ml of ethanol. To this was added BSEN-H~ (0.005 mole) in 50 ml of ethanol. Air was bubbled through the mixture for about 6 hr, followed by refluxing on water-bath for [ hr. The reddish brown compound, thus obtained, was filtered and washed with an ether-alcohol mixture (50:50) and finally with ether. The compound was dried in a desiccator over fused calcium chloride. The compound is soluble in coordinating solvents, sparingly soluble in water, ethanol and methanol and insoluble in carbon-tetrachloride, ether and benzene. It is non-conducting in DMSO.
N,N'- Trimethylenebis( salicylideneiminato ) salicylaldehydato manganese(III), [Mn(BSTN)(sal)], (IV). The method used to isolate the compound fill) gave this brown compound [Mn(BSTN)(sal)]. It is soluble in coordinating solvents, sparingly soluble in water, ethanol and methanol, but insoluble in carbon-tetrachloride, ether, and benzene. It is non-conducting in DMSO.
N,N'-Ethylenebis(salicylideneiminato ) ethylenediamine manganese(Ill) perchlorite, [Mn(BSEN)(en)] C10,, (V). To a hot solution of N,N'-ethylenebis(salicylideneiminato) manganese(II) (0.005 mole) in 50 ml of ethanol was added an ethanolic (50 ml) solution of ethylenediamine (0-005 mole). The mixture was refluxed for half an hour and filtered while hot. The brown filtrate was treated with a stoichiometric amount of a methanotic solution of sodium perchlorate and the volume was reduced to half. On standing a brown crystalline compound separated, it was filtered, washed with ethanol and dried in a desiccator over fused calcium chloride.
696
K. DEY and K. C. RAY
It is soluble in water, ethanol and coordinating solvents, but insoluble in ether, benzene, carbon tetrachloride. The molar conductance value (Au) of an 1'5 × 10-3 M ethanol solution was found to be 72 fF 1cm2 mole-~ at 28°C, showingthe presence of a 1 : 1 electrolyte in this solvent.
N,N'-Ethylenebis(salicylideneiminato) bipyridino manganese(llI) perchlorate, [Mn(BSEN)(bipy)]CIO,,(VI). This brown compound was isolated by the method described for (V), using dipyridyl instead of ethylenediamine. It is soluble in water, ethanol, and coordinating solvents but insoluble in carbon tetrachloride, ether and benzene. The ~.,~ value of an 1.8× 10-3M ethanol solution was found to be 98 ohm-~ cm2 mole-' at 28°C, showing the presence of an 1:1 electrolyte in this solvent. RESULTS AND DISCUSSION When bis(acetylacetonato) manganese(II) or bis(salicylaldehydato) manganese(II) was reacted with preformed quadridentated Schiff bases in absolute alcohol in the presence of oxygen, heterochelates of the type [Mn(Lig)(L-L)]nH20 (where, Lig=dianions of the Schiff bases BSEN-H2 and BSTN-H2; L - L ---anion of acetylacetone and salicyaldehyde) were isolated. The reaction of N,N'-ethylene bis(salicylidineiminato) manganesed(II) with ethylenedianine or dipyridyl in air produced the heterochelates [Mn(BSEN)(en)] ÷ or [Mn(BSEN)(dipy)]+, which were isolated as perchlorates. The heterochelates are all paramagnetic and show magnetic moment values in the range 5.00-4.70 B.M. at room temperature (Table 1) indicating the presence of tervalent manganese. These values show the absence of exchange or superexchange interactions. The complexes(I)-(IV) are found to be virtually nonconducting in DMSO, while compounds (V) and (VI) show molar conductances 72.00 and 98.00 ohm-' cm -2
mole-' respectively in dry methanol, which demonstrates some dissociation in the medium. The electronic absorption bands along with their log E values are given in Table 2. Usually high-spin manganese(Ill) complexes with octahedral geometry are expected to give[14] one charge-transfer band around 25,000 cm -1 (log E = 3.5) and a spin-allowed d-d transition band, ~Eg--,~T:g around 20,000cm -1 (log e =2.5). The electronic absorption spectra of the present manganese(III) heterochelates, measured in the region 14,000-15,000 cm-', consist of several intense bands and shoulders. The positions of the bands can be roughly divided into two areas which lie between 14,000-15,000 cm -1 and 16,000-25,000 cm -1. The bands at high wave numbers are seen as shoulders on intense charge-transfer absorptions. The absorption in the visible region 16,000-25,000 cm -~ can be assigned to the 5E~ 5T2~ transition, though there is the possibility that the bands at -25,000 cm -1 may be of charge-transfer origin. The splitting of the bands is most likely due to the John-Teller distortion as observed in many complexes of manganese(III)[1, 15]. Despite much work on manganese(III) chelates[l, 15], difficulties have arisen in the assignment of the bands in the near-infrared region. High-spin manganese(III) complexes always show at least one absorption in the region 8000-13,000cm -~. The relationship of this band to the structure of the complexes has not been clarified. We also observe a band in the region 14,000-15,000cm-~. However, such a band has recently been assigned as a low-energy charge-transfer transition in such chelates[15]. The numerical data on the i.r. spectra of the manganese(III) heterochelates are recorded in Table 3. For the complexes [MN(BSEN](acac)]2H:O, (I) and
Table 1. Elemental analyses and magnetic moments of manganese(Ill)heterochelates Found %
Cald. % /zo.(B.M.)
Complex* [Mn(BSEN)(acac)].2H20, (I) [Mn(BSTN)(acac)],(II) [Mn(BSEN)(sal)],(III) [Mn(BSTN)(sal)],(IV) [Mn(BSEN)(en)]C104,(V) [Mn(BSEN)(dipy)]CIO,, (VI)
C
H
N
Mn
C
I4
N
Mn
(roomtemp.)
55.82 61.02 62.58 62.88 45.22 53.48
5.20 5.45 4.50 3.98 5.02 4.96
5.81 7.00 6.03 5.88 12.00 10.00
12.01 13-02 12.00 11.92 10.96 10.08
55.26 60.82 62.44 63' 16 44.96 54.08
5.48 5.30 4.30 4.16 4.58 3.82
6.14 6.45 6.33 6.14 11.66 9.71
12.06 12.68 12.46 12.06 11.45 9.53
5.00 4.82 4.70 4.82 4.90 5.00
*BSEN = N,N'-ethylenebis(salicylideneiminato) dianion. BSTN= N,N'-trimethylenebis(salicylidineiminato) dianion, acac= acetylacetonate anion, en = ethylenediamine, dipy = dipyridyl. Table 2. Electronic spectral data of manganese(III)-heterochelates Complex [Mn(BSEN)(acac)]2H20, (I) [Mn(BSTN)(acac)],(II) [Mn(BSEN)(sal)],(III) [Mn(BSTN)(sal)],(IV) [Mn(BSEN)(en)]C10,, (V)
Solvent MeOH MeOH DMSO DMSO EtOH
Vmaxin cm-' (log Emo~) 40,000(4.3); 35,700(4.2); 24,800(sh); 20,600(sh); 16,500(2.4), 41,600(sh); 35,700(4.1); 32,700(sh); 20,400(2.7); 19,600(sh); 18,000(sh). 25,000(3.8); 15,600(sh); 14,200(sh). 30,O00(sh); 17,850(2.6); 16,000(sh); 14,500(sh). 40,450(4.6); 41.666(4.6); 36,000(4.2); 32,500(sh); 29,400(sh); 27,000(sh); 17,000(sh); 15,400(sh).
697
Manganese(Ill)heterochelates Table 3. Infrared spectra (KBr phase) of some manganese(III)heterochelates [Mn(BSEN)(acac)]2H20, (I) lMn(BSTN)(acac)],(II) [Mn(BSEN)(sal)],(III)
[Mn(BSTN)(sal)],(lV)
[Mn(BSEN)(en)]CIO., (V) [Mn(BSEN)(dipy)]CIO4,(VI)
3500(m); 1675(sh); 1650(vs); 1610-1550(s,doublets); 1500-1450(s,doublets); 1395(sh); 1345(s); 1300(vs); 1200(m); 1165(m); 1145(m); 1095(vs); 1050-1040 (w, dpibfiets); 910(m); 860-840(w,doublets); 810(m); 765(s). 3550(s); 3000(sh); 1620-1530(s,doublet); 1498(sh); 1450(vs); 1300(vs); 1210 (Br,); l150(m); 1135(m);910(m); 855(br,w); 810(m); 765(s). 3070-3000(w,triplets); 1650(sh); 1640(vs); 1610(s); 1550(m); 1475(m,doublet); 1410(vw); 1400(m); 1340(m); 1290(m); 1250(m); 1205(w); l190(m); l150(s); l130(m); 1095(w); 1050(w);995(w); 980--950(w,triplet); 910(m); 865(m,doublet): 825(m); 810(m); 798(sh); 775(m); 765(vs). 3060-2900(w,triplet); 1650(vs); 1620(s); 1575(s); 1500(s); 1498(vs); 1460(vs); 1400(m); 1350(sh); 1315(vs); 1210(m); ll701s); l140(m); l ll5(sh); 1075 (w, doublet); 1040(w);980(w); 940(sh): 910(s); 860(w,doublet); 820(sh); 810(m); 795(sh); 762(s); 745(m). 3040(m,br); 1645(vs); 1615(sh); 1550(s); 1495(m); 1400(m); 1340(w); 1300(s); 1210(w); 1180-1080(vs,br); 980(w,br); 910(m); 860(w,br); 810(m); 760(m,doublets). 3050-2900(w,triplets); 1655(sh); 1650(vs); 1620(vs); 1560(vs); 1480(s); 1450(vs); 1425(sh); 1400(sh); 1350(sh); 1340(s); 1305(vs); 1280(s); 1255(w,doublet); 1245(sh); 1225(sh); 1210(s); 1175(m); l150-1060(br,vs); 1050(s); 1040(sh); 1025(sh); 980(m,doublet): 975(m); 945(w); 910(m): 810(s); 800(sh); 780(s); 775(m); 765(sh); 755(vs).
[Mn(BSTN)(acac)], (II), the chelate oxygen-bonded acetylacetonate anion is shown in the vibrational spectral data[16,17] where we found v c ~ at 1550cm -~ and 1530 cm ~' respectively for complexes (I) and (II), while vc'-"cis observed at about 1500 cm ' for both chelates. The wc=o for the carbon-bonded acetylacetone occurs above 1650 cm ~[18]. Despite the added complexities due to the presence of C=N and C=C stretching modes of the present Schiff bases, the vibrational spectral data of (I) and (II) clearly show the presence of the oxygen-bonded chelating acetylacetonate anion. Infrared spectra of quandridentate Schiff bases and their metallic complexes have been discussed thoroughly[19, 21]. The present quadridentate Schiff bases have weak to medium (but broad) bands around 2700 cm -~ assignable to intremolecular hydrogen bonded OH groups, while vc-N appeared around 1630 c m ~ in the free ligands. The broad and weak band due to vo. disappears in the complexes indicating the metal-oxygen (phenolic) bond formation in the present mixed ligand complexes of manganese(III). The vc=N in the complexes was observed around 1610-1620cm-' indicating the coordination of imine nitrogen[22]. The phenolic C-O in the Schiff bases is observed around 1280 cm -t, which is shifted to the region 1300-1350 cm-' in the mixed chelates [22]. Characteristic bands for water molecule for complex (I) are observed at 3500 cm 1 assignable to VOHand at -1650 cm-' assignable to 8oH [23]. The i.r. spectral data of complexes(V) and (VI) show a strong and broad band in the range 1060-1150 cm L assignable to the v3 mode of C104 ion vibration (in Td symmetry) [24-26]. This band demonstrates the presence ionic perchlorate in these two chelates. The N-H stretching frequency in complex (V) occurs at 3040 c m t, demonstrating the coordinated NH2 group[27, 28]. From the above observations it may be concluded that the quadridentate Schiff bases in the present manganese(III) heterochelates, [Mn(Lig)(L-L)] have been rearranged from a planar to a twisted conformation by the
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