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HEXAAZA MACROCYCLIC LIGAND compound [Mn 4(µ-OH) 4(CO) 12] 1 in 32 % yield.
1,3,6,8,11,14-HEXAAZA TRICYCLOOCATADECANE, The solid state structure of complex 1 has been
METAL = Ni(II), Cu(II). J. Bang. Acad. Sci,. determined by single crystal X-ray diffraction
2006, 30 (1), 39-45. study at low temperature 150(2) K. Complex 1
crystallizes in the monoclinic space group C2/c
The crystal and molecular structures of the with a = 11.4533(3), b = 14.6799(4), c=21.0289(5)
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3
complexes Ni(A)C1 2.2H 2O and Cu(A)CIPF 6 where Å, β= 102.313(2) , V = 3454.33(15) Å and Z= 4.
A= C 12H 26N 6 have been determined by single Molecular structure determination reveals that the
crystal X-ray diffraction method. Ni(A)C1 2.H 2O, complex 1 is a distorted cube of four Mn atoms
Mol. wt = 1811.5 is orthorhombic, space group and four µ 3-OH groups. An interesting feature is
pbca,a=14. 146(3), b=8.759(1), c = 14.620(3)ÅV that out of the four µ 3-OH groups, two are seen to
-
-
3
3
= 18.11.5(6) Å , Z = 4, d calc =1.540 mg/m , µ = attach to CH 3(CH 3)C(O)CH 2CH(CH 3)(O) ion/molecule
-1
1.383 mm , F(000) = 888, R = 0.025 for 2178 presumably derived from acetone via H-bonding.
unique observed reflections. Cu(A) C1.PE 6 Mol.
wt. =947.9 is orthorhombic, space group P2 12 1.2 a 073 CHOWDHURY, M.Z.A. & SHYAM,
= 10.305(3), b = 14.175(1), c = 6.489(1) Å, V = L.K. (Dept. of Chemistry, University of
3
947.9(3), Z = 2, d calc = 1.746 mg/m , µ = 1.445 Chittagong, Chittagong). EFFECT OF SAME-
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mm , F(000) = 510, R = 0.0624 for 1103 unique SYMMETRY ATTRACTION ON THE BOND
observed reflections. Hexaaza tricvclomacrocyclic LENGTH OF AB 2 MOLECULES. J. Bang. Acad.
24
complex 5 is formed with Ni(C 12 H 26 N 6 cation. Sci., 2007, 31 (1), 79-85.
The coordination geometry of Ni(II) is nearly
square planar with Ni-N distances of 1.9229, The two A-B bonds in all AB 2 molecules, either
1.9229, 1.9410 and 1.9410 Å. Of the four N-Ni-N bent or linear, are found to be equal in length. A
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angles two are 87.02(6) and another two are theoretical investigation indicates that the same-
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92.98(6) . Two water molecules are present and Cl symmetry attraction among the valence orbitals
atom is hydrogen bonded to two hydrogen atoms is of their central atoms may play an important role
one of a water molecule and the other is from NH in their molecular orbital formation in such a
group. Tricyclomacrocyclic complex of Cu(II) way that the two A-B distances become equal. In
+
namely, the cation C u(C 12H 26N 6)Cl] is formed the bent AB 2 molecules, the central atom uses
-
which is held electrostatically by PF 6 ion in the two energetically different orbitals (s and p y) for
crystal packing. The coordination geometry of bonding. In the valence shell of this atom, a non-
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Cu(II) is distorted square pyramidal with Cl at the bonding orbital p Z' which has the same-
apex. Of the four Cu-N bonds two are 2.029 Å symmetry property as the bonding s orbital, can
each and another two are 2.040 Å each. The N-Cu- destabilize the s orbital so that its energy comes
N bond angles are 88.2(3) 90.0(3), 90.0(3) and closer to that of p y to form two equal A-B bonds.
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88.2(3) respectively and N-Cu-Cl angles are Similarly, in the linear AB 2 molecules the
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102.2(2) each. central atom employs s and p Z orbitals for
bonding. But a non-bonding d z orbital which
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072 BEGUM,N; KABIR, S.E.; MIAH, has the same-symmetry property as the bonding
M.A. (Dept. of Chemistry, Jahangirnagar s orbital, increases the energy of s by the
University, Savar, Dhaka). HOSSAIN, G. M. G. symmetry-attraction so that s and p Z become
(School of Chemistry, Cardiff University, Cardiff, comparable in energy to form two equal A-B
CF103AT, U.K). SOLID-STATE MOLECULAR bonds.
STRACTURE OF [Mn 4(µ-OH) 4(CO) 12]IN A NEW
UNIT CELL DIMENSION. J. Bang. Acad. Sci., 074 CHOWDHURY, M.Z.A. SHYAM, L.K.;
2007, 31 (1), 25-32. & MANNAN, M.A; (Dept of Chemistry,
University of Chittagong, Chittagong). STUDIES
Decarbonylation of [Mn 2 (CO) 10 ] with Me 3NO.2H 2O ON THE A-B BOND DISTANCES IN AB 6
followed by addition of morpholine, (NC 4H 9O) in MOLECULES BY THE SYMMETRY-
refluxing acetone afforded the tetranuclear cluster
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