Self-assembled Transition Metal Coordination Frameworks of ...

Ni(Il) complexes
In the case of compound 2, two major peaks are obtained at m/z l827.1019
and l765.l557 (Fig. 3.3). Here the peak at l765.l557 is assigned as the
[Ni4(HL3)L33]+ ion (calc. 1765). The base peak at l827.l0l9 is assigned as the
molecular ion peak with two methanol molecules (calc. 1827). The other peak at
1323.1211 is assigned as [Ni,(HL3)L32]* (calc. 1323).
Considering the carbohydrazone compounds, the MALDI MS spectrum of
compound 3 (Fig. 3.4) displays only two main peaks centered at m/z 479.0873, as
base peak, and l917.4364, the molecular ion peak. The former peak is assigned as
[Ni(HL")]* (calc. 479) and the latter as [Ni4(I-IL")L“3]+ ion (calc. 1917) (Fig. 3.5),
agreeing well with simulations and being characteristic results. The spectrum also
implies the stability as evidenced by only two major peaks for assigned formula of
[Ni(HL4)]4(PF6)4- 12H2O. The small peaks centered at m/z 536 and 958 are assigned
as [Ni2(L“)-H+]* (calc. 535) and [Ni2(HL“)L"]+ (calc. 957) respectively, also agreeing
well with calculated isotropic pattems.
The complex 4, however, exhibits many peaks (Fig. 3.6). Of these, the peaks
at 477.0968 and base peak centered at l909.4594 are assigned as [Ni(HL5)]+ (calc.
477) and [Ni4(HL5)L53]+ ion (calc. 1909), agreeing well with calculated isotropic
distribution pattems. The latter peak is characteristic of a molecular square structure
and the former is its monomer, usually obtained under MALDI ionization. The two
other major peaks at 101 1.1215 and 1487.2386 assigned as [Ni3(L5)2-H+]+ (calc. l0l 1)
and [Ni4(L5)3-HT (calc. 1487) respectively also support the assigned molecular
square structure [Ni(HL5)]4(PF(,)4- 9H2O. Another peak centered at 24435110 is
assigned as [Ni4(HL5)3L5(PF6)2- 2CH2Cl2- 4112o]* (calc. 2443). However some
weaker peaks at l100.0369 and l264.l392 are assigned as [Ni3(L5)2Cl- 3H2O]+ (calc.
1101) and [Ni3(L5)2C1- H2O+benzoylpyridine hydrazone]+ (calc. 1262) respectively,
may be due to the presence of impurity of chloride complex. All these isotropic
patterns and their simulations are given in Figs. 3.7 to 3.9. These results, however, are
indicative of the stability of Ni(1I) molecular squares in the solution phase.
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