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A stable nickel(III) complex derived from a new hexadentate ligand
INORC. NUCL. CHEM. LETTERS Vol.14, pp. 441-444, 1978. Pergamon Press. Printed in Great Britain
A STABLE NICKEL(Ill) COMPLEX DERIVED FROM A NEW HEXADENTATE LIGAND A. N. Singh, J.G. Mohanty and A. Chakravorty Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta 700032, India and Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India. (Received 30 June 1978; received for publication 31 August 1978)
Due to efforts made during the past few years nlokel(Ill) is now known (I-3) in combination with a number of nitrogenous ligands.
However, if
the macrocyclic systems (3) are excluded, very few well-oharacterlzed species have been isolated in the crystalline state and where isolated (I) these are either insoluble or unstable or both.
In this communication we report a
stable nickel(lll) complex of the hexadentate ligand 1 obtained by 1:1 condensation of biacetyl monoxime and tetraeth~lenepentamine.
The ligand is
abbreviated as HL where H refers to the dissooiable oxime proton.
H3C~NOH H~C N(CHzCH2 NI-I)3 CHzCH2NH2 I The brown nickel(ll) complex, Ni(HL)(CI04)2, is regdily obtained by reacting the ligand with nickel(ll) perchlorate in aqueous ethanol.
Its
properties (some are shown in TABLE I) are closely akin to those of related systems having pseudooctahedral NiN 6 coordination sphere (4). Thus this sphere also occurs in Ni(HL) 2+ as shown in 2_~a. Ni(HI)(CI04) 2 is readily oxidised by aqueous alkaline (NH4)2S208 to yield a dark-red solution from which red crystals of composition Ni(L)(CIO4) 2 deposit on cooling. 441
Anal. Calcd. for
442
A New Hexadentate Ligand
TABLE Ia Magnetic Moment ( ~ , Conductivity Frequencies ( ~ '
Compound
(A
BM) in Solid State, Molar Electrical
, ohm-lcm2mol-1) in Nitromethane Solution,
( ~ , cm -I ) and Extinction Coefficients
M"lom-1) of Electronic Bands in Aqueous Solution.
0(0
F
A
Ni(H~)(Ol04) 2
3.00
171b
12,270(29)c; 19,600(75) d
Ni(L)(CI04) 2
2.12
170b
20,000(2400)e; 25,300(1700) e
a All measurements were done at about 300°K. b 1 : 2 electrolytic behaviour
o Octahedral
~I
d Octahedral
~2 transition.
(W.J. Greary, Coord. Chem. Rev., ~, 81 (1971)).
transition.
• Charge transfer band.
012H27N609CI2Ni
: C, 27.23; H, 5.10; N, 15.88; Ni, 11.10. Found: C, 27.30;
H, 5.08! N, 15.89; Ni, 11.08.
The compound is stable both in the solid state
and in solution. Selected properties of Ni(L)(CI04) 2 are set in TABLE I.
It is a 1:2
electrolyte in nitromethane solution which also exhibits an isotropic epr signal with
g = 2.10.
Bulk paramagnetis= of powdered samples correspond to
a spin-doublet ground state having unquenched orbital contribution.
Such
samples also exhibit strong epr signals even at room temperature. The spectrum fits with an S = ~ state in an axial field characterised by gl = 2.13.
g|| = 2.03 and
An effective tetragonal structure with an unpaired electron in a
dz 2 orbital (5) is indicated. Evidently Ni(L) 2+ contains low-spln nickel(lll) (d7 configuration), the most probable coordination sphere being 2b. The Ni(L) 2+ - Ni(HL) 2+ interconversion is readily achieved in aqueous solution using the cyclic voltammetric technique (Pt-electrode).
For example
in phosphate buffered (pH 5.95) 0.1M aqueous NaCI the average of anodic and cathodic peak potentials is + O.281V versus saturated calomel electrode (scan
A New Hexadentate
Ligand
443
/
/R
2+
!// 2a : R=OH~ R'-H2 2b: R=O~ R~H 2
rate 10 mVs-1). The peak-to-peak separation is 90 mV. is thus quasi-reversible.
The electrode process
The peak potentials are pH-dependent implicating
the participation (6) of protons in the electrode process as in: Ni(L) 2+ + e + H +
~ Ni(HL) 2+
References I. D. Sen and C. Saha, J. Chem. Soc. Dalton, 776 (1976); R.S. Drago and E.I. Bauoom, Inorg. Chem., 1!I, 2064 (1972); J. J. Bour, P.J.M.W.L. Birker and J.J. Steggerda, Inorg. Chem., 10, 1202 (1971); A. V. Babaeva, I.B. Baranovskii and G. G. Afanaseva, Russ. J. Inorg. Chem., 10, 686 (1965). 2. F.P. Bossu and D.W. Margerum, Inorg. Chem., 16, 1210 (1977); I.N. Marcy, E.K. Ivanova, A.T. Panfilov and N.P. Luneva, Russ. J. Inorg. Chem., 20, 67 (1975); J. Lati, J. Koresh and D. Meyersteln, Chem. Phys. Lett., 33, 286
( 1975 ) •
3. A. Deslderl, J.B. Raynor and C.K. Peon, J. Chem. Sec. Dalton, 205 (1977); E.K. Barefield and M.T. Mocella, J. Am. Chem. 8oc., 97, 4238 (1975); F.V. Lovecchio, ~.S. Gore and D.H. Busch, J. Am. Chem. See., 96, 3109 (1974); D.C. Olson and J. Vasilevskis, Inorg. Chem., 8, 1611 (1969); N.F. Curtis and D.F. Cook, Chem. Comm., 962 (1967).
44&
A New Hexadentate Ligand
4. J.G. Mohanty, R.P. Singh and A. Chakravorty, Inorg. Chem., 14, 2178 (1975); J.G. Mohanty and A. Chakravorty, Indian J. Chem., 12, 883 (1974)! J. G. Mohanty and A. Chakravorty, Inorg. Chem., 15, 2912 (1976); A.N. Singh R.P. Singh, J.G. Mohanty and A. Chakravorty, Inorg. Chem., 16, 2597 (1977). 5. A.H. Makl, N. Edeleteln, A. Davlson and R.H. Holm, J. Am. Chem. See., 86, 4580 (1964). 6. J. G. Mohanty and A. Chakravorty, Inorg. Chem., 16, 1561 (1977).
A STABLE NICKEL(Ill) COMPLEX DERIVED FROM A NEW HEXADENTATE LIGAND A. N. Singh, J.G. Mohanty and A. Chakravorty Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta 700032, India and Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India. (Received 30 June 1978; received for publication 31 August 1978)
Due to efforts made during the past few years nlokel(Ill) is now known (I-3) in combination with a number of nitrogenous ligands.
However, if
the macrocyclic systems (3) are excluded, very few well-oharacterlzed species have been isolated in the crystalline state and where isolated (I) these are either insoluble or unstable or both.
In this communication we report a
stable nickel(lll) complex of the hexadentate ligand 1 obtained by 1:1 condensation of biacetyl monoxime and tetraeth~lenepentamine.
The ligand is
abbreviated as HL where H refers to the dissooiable oxime proton.
H3C~NOH H~C N(CHzCH2 NI-I)3 CHzCH2NH2 I The brown nickel(ll) complex, Ni(HL)(CI04)2, is regdily obtained by reacting the ligand with nickel(ll) perchlorate in aqueous ethanol.
Its
properties (some are shown in TABLE I) are closely akin to those of related systems having pseudooctahedral NiN 6 coordination sphere (4). Thus this sphere also occurs in Ni(HL) 2+ as shown in 2_~a. Ni(HI)(CI04) 2 is readily oxidised by aqueous alkaline (NH4)2S208 to yield a dark-red solution from which red crystals of composition Ni(L)(CIO4) 2 deposit on cooling. 441
Anal. Calcd. for
442
A New Hexadentate Ligand
TABLE Ia Magnetic Moment ( ~ , Conductivity Frequencies ( ~ '
Compound
(A
BM) in Solid State, Molar Electrical
, ohm-lcm2mol-1) in Nitromethane Solution,
( ~ , cm -I ) and Extinction Coefficients
M"lom-1) of Electronic Bands in Aqueous Solution.
0(0
F
A
Ni(H~)(Ol04) 2
3.00
171b
12,270(29)c; 19,600(75) d
Ni(L)(CI04) 2
2.12
170b
20,000(2400)e; 25,300(1700) e
a All measurements were done at about 300°K. b 1 : 2 electrolytic behaviour
o Octahedral
~I
d Octahedral
~2 transition.
(W.J. Greary, Coord. Chem. Rev., ~, 81 (1971)).
transition.
• Charge transfer band.
012H27N609CI2Ni
: C, 27.23; H, 5.10; N, 15.88; Ni, 11.10. Found: C, 27.30;
H, 5.08! N, 15.89; Ni, 11.08.
The compound is stable both in the solid state
and in solution. Selected properties of Ni(L)(CI04) 2 are set in TABLE I.
It is a 1:2
electrolyte in nitromethane solution which also exhibits an isotropic epr signal with
g = 2.10.
Bulk paramagnetis= of powdered samples correspond to
a spin-doublet ground state having unquenched orbital contribution.
Such
samples also exhibit strong epr signals even at room temperature. The spectrum fits with an S = ~ state in an axial field characterised by gl = 2.13.
g|| = 2.03 and
An effective tetragonal structure with an unpaired electron in a
dz 2 orbital (5) is indicated. Evidently Ni(L) 2+ contains low-spln nickel(lll) (d7 configuration), the most probable coordination sphere being 2b. The Ni(L) 2+ - Ni(HL) 2+ interconversion is readily achieved in aqueous solution using the cyclic voltammetric technique (Pt-electrode).
For example
in phosphate buffered (pH 5.95) 0.1M aqueous NaCI the average of anodic and cathodic peak potentials is + O.281V versus saturated calomel electrode (scan
A New Hexadentate
Ligand
443
/
/R
2+
!// 2a : R=OH~ R'-H2 2b: R=O~ R~H 2
rate 10 mVs-1). The peak-to-peak separation is 90 mV. is thus quasi-reversible.
The electrode process
The peak potentials are pH-dependent implicating
the participation (6) of protons in the electrode process as in: Ni(L) 2+ + e + H +
~ Ni(HL) 2+
References I. D. Sen and C. Saha, J. Chem. Soc. Dalton, 776 (1976); R.S. Drago and E.I. Bauoom, Inorg. Chem., 1!I, 2064 (1972); J. J. Bour, P.J.M.W.L. Birker and J.J. Steggerda, Inorg. Chem., 10, 1202 (1971); A. V. Babaeva, I.B. Baranovskii and G. G. Afanaseva, Russ. J. Inorg. Chem., 10, 686 (1965). 2. F.P. Bossu and D.W. Margerum, Inorg. Chem., 16, 1210 (1977); I.N. Marcy, E.K. Ivanova, A.T. Panfilov and N.P. Luneva, Russ. J. Inorg. Chem., 20, 67 (1975); J. Lati, J. Koresh and D. Meyersteln, Chem. Phys. Lett., 33, 286
( 1975 ) •
3. A. Deslderl, J.B. Raynor and C.K. Peon, J. Chem. Sec. Dalton, 205 (1977); E.K. Barefield and M.T. Mocella, J. Am. Chem. 8oc., 97, 4238 (1975); F.V. Lovecchio, ~.S. Gore and D.H. Busch, J. Am. Chem. See., 96, 3109 (1974); D.C. Olson and J. Vasilevskis, Inorg. Chem., 8, 1611 (1969); N.F. Curtis and D.F. Cook, Chem. Comm., 962 (1967).
44&
A New Hexadentate Ligand
4. J.G. Mohanty, R.P. Singh and A. Chakravorty, Inorg. Chem., 14, 2178 (1975); J.G. Mohanty and A. Chakravorty, Indian J. Chem., 12, 883 (1974)! J. G. Mohanty and A. Chakravorty, Inorg. Chem., 15, 2912 (1976); A.N. Singh R.P. Singh, J.G. Mohanty and A. Chakravorty, Inorg. Chem., 16, 2597 (1977). 5. A.H. Makl, N. Edeleteln, A. Davlson and R.H. Holm, J. Am. Chem. See., 86, 4580 (1964). 6. J. G. Mohanty and A. Chakravorty, Inorg. Chem., 16, 1561 (1977).