Elorriaga David, Carrillo-Hermosilla Fernando, Antiñolo Antonio, López-Solera Isabel, Fernández-Galán Rafael, Villaseñor Elena
Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Campus Universitario, Ciudad Real, 13071, Spain.
Dalton Trans. 2014 Dec 14;43(46):17434-44. doi: 10.1039/c4dt01975j.
The new monoguanidinato complexes [Nb(NMe2)2{N(2,6-(i)Pr2C6H3)}{(NR)(NR')C(NMe2)}] (R = R' = (i)Pr, 2; R = (t)Bu, R' = Et, 3) were obtained by the insertion reaction of either diisopropylcarbodiimide or 1-tert-butyl-3-ethylcarbodiimide with the triamido precursor [Nb(NMe2)3(N-2,6-(i)Pr2C6H3)] (1) bearing a bulky imido moiety. The μ-oxo derivative [{N(2,6-(i)Pr2C6H3)}{(N(i)Pr)2C(NMe2)}(NMe2)Nb]2(μ-O) (2a) was formed by an unexpected hydrolysis reaction of the amido niobium compound 2. Alternatively, monoguanidinato complexes [Nb(NMe2)2{N(2,6-(i)Pr2C6H3)}{(N(i)Pr)2C(NHR)}] (R = (i)Pr, 4, (n)Bu, 5) can be obtained by protonolysis of 1 with N,N',N''-alkylguanidines [(NH(i)Pr)2C(NR)] (R = (i)Pr, (n)Bu). Compound also reacts with either tert-butylisocyanide or 2,6-xylylisocyanide to give, by a migratory insertion reaction, the corresponding iminocarbamoyl compounds [Nb(NMe2)2{(NMe2)C=NR}{N(2,6-(i)Pr2C6H3)}] (R = (t)Bu, 6, Xy, 7). Addition of the neutral alkylguanidines to complex 6 results in a facile C-N bond cleavage at room temperature in a process directed by the formation of the stable chelate complex 4 or 5. Complex reacts with heterocumulenic CS2 to produce new imido dithiocarbamato complexes [Nb(NMe2){S2C(NMe2)}2{N(2,6-(i)Pr2C6H3)}] (8) and [Nb{S2C(NMe2)}3{N(2,6-(i)Pr2C6H3)}] (9). These complexes do not react with alkylguanines, although new mixed guanidinato dithiocarbamato complexes [Nb(NMe2){S2C(NMe2)}{(N(i)Pr)2C(NHiPr)}{N(2,6-(i)Pr2C6H3)}] (10) and [Nb{(S2C(NMe2)}2{(N(i)Pr)2C(NH(i)Pr)}{N(2,6-(i)Pr2C6H3)}] (11) can be obtained by reaction of complex 4 with one or two equivalents of CS2, respectively. All of the complexes were characterized spectroscopically and the dynamic behaviour of some of them was studied by variable-temperature NMR. The molecular structures of 2a, 3, 6 and 10 were also established by X-ray diffraction studies.
新型单胍基配合物[Nb(NMe2)2{N(2,6-(i)Pr2C6H3)}{(NR)(NR')C(NMe2)}]（R = R' = (i)Pr，2；R = (t)Bu，R' = Et，3）是通过二异丙基碳二亚胺或1-叔丁基-3-乙基碳二亚胺与带有庞大亚氨基部分的三酰胺前体[Nb(NMe2)3(N-2,6-(i)Pr2C6H3)]（1）的插入反应得到的。μ-氧代衍生物[{N(2,6-(i)Pr2C6H3)}{(N(i)Pr)2C(NMe2)}(NMe2)Nb]2(μ-O)（2a）是由酰胺基铌化合物2发生意外的水解反应形成的。另外，单胍基配合物[Nb(NMe2)2{N(2,6-(i)Pr2C6H3)}{(N(i)Pr)2C(NHR)}]（R = (i)Pr，4，(n)Bu，5）可通过用N,N',N''-烷基胍[(NH(i)Pr)2C(NR)]（R = (i)Pr，(n)Bu）对1进行质子解反应得到。化合物还与叔丁基异氰化物或2,6-二甲苯基异氰化物反应，通过迁移插入反应生成相应的亚氨基甲酰基化合物[Nb(NMe2)2{(NMe2)C=NR}{N(2,6-(i)Pr2C6H3)}]（R = (t)Bu，6，Xy，7）。向配合物6中加入中性烷基胍会在室温下导致一个由稳定螯合配合物4或5的形成所引导的过程中C-N键的轻松断裂。配合物与杂累积二烯CS2反应生成新的亚氨基二硫代氨基甲酸盐配合物[Nb(NMe2){S2C(NMe2)}2{N(2,6-(i)Pr2C6H3)}]（8）和[Nb{S2C(NMe2)}3{N(2,6-(i)Pr2C6H3)}]（9）。这些配合物不与烷基胍反应，不过新的混合胍基二硫代氨基甲酸盐配合物[Nb(NMe2){S2C(NMe2)}{(N(i)Pr)2C(NHiPr)}{N(2,6-(i)Pr2C6H3)}]（10）和[Nb{(S2C(NMe2)}2{(N(i)Pr)2C(NH(i)Pr)}{N(2,6-(i)Pr2C6H3)}]（11）可分别通过配合物4与一当量或两当量的CS2反应得到。所有配合物都通过光谱进行了表征，并且通过变温核磁共振研究了其中一些配合物的动态行为。2a、3、6和10的分子结构也通过X射线衍射研究得以确定。
