Manipulation of molecular and supramolecular structure in nickel(II) complexes through the orientation of dicarboxylate hydrogen bonding faces

The reactions of the bis(thiosemicarbazide)nickel(II) nitrates [NiL2](NO3)(2) [1a, L = tsc, NH2C(S)-NHNH2; 1b, L = Metsc, MeNHC(S)NHNH2; 1c, L = Ettsc, EtNHC(S)NHNH2; 1d, L = Me(2)tsc, NH2C(S)NHNMe2; and le, L = Me(3)tSC, MeNHC(S)NHNMe2] with a range of sodium dicarboxylates led to crystalline products in 19 cases. The reaction with dicarboxylates containing an angle theta of 180degrees between the carboxylate groups generally led to compounds in which the cations and anions are linked into tapes through hydrogen bonding, and the crystal structures of [Ni(tsc)2(OH2)(2)][fumarate] (2), [Ni(Me(2)tSC)(2)(OH2)(2)][fumaratel-H2O (3), [Ni(Me(2)tsc)(2)(OH2)(2)][fumarate] (4), and [Ni(tsc)(2)][4,4'-biphenyldicarboxylate].5H(2)O (5) are reported. A similar tape structure is observed in the crystal structure of [Ni(Me(3)tsc)(2)(OH2)(2)] [isophthalatel . 3.2H(2)O (6) in which the isophthalate anion has an angle theta of 120degrees between the carboxylate groups. However, such tape structures are not seen with dicarboxylates in which theta is less than 90degrees, and instead, one of three structural types is observed. These are tris(thiosemicarbazide)nickel(II) dicarboxylates, witnessed by the crystal structures of [Ni(tsc)(3)] [maleate].H2O (7) and [Ni(Ettsc)(3)] [phthalate].4H(2)O (8), neutral compounds containing coordinated dicarboxylates, epitomized by the crystal structures of [Ni(Me(3)tSC)(2)(phthalate)] .2H(2)O (9), [Ni(Me(2)tSC)(2)(itaconate)].6H(2)O (10), and [Ni(Me(3)tSC)(2)(homophthalate)].4H(2)O (11) and neutral bis(thiosemicarbazidato)nickel(II) complexes in which the dicarboxylate has acted as a base. Thermogravimetric analyses for the hydrogen-bonded tape structures 2-6 and the coordinated dicarboxylate compounds 9-11 are reported.