| Abstract |
The cyanamides NCNR2 (R-2 = Me-2, Ph-2, C5H10) react with ZnX2 (X = CL Br, I) in a (2): 1 molar ratio at RT, giving a family of zinc(n) complexes VnX(2)(NCNR2)(2)1 (R-2 = Me-2, X = Cl 1, X = Br (2), X = I 3; R-2 = C5H10, X = Cl 4, X = Br 5; X = I 6; R-2 = Ph-2, X = Cl 7, X = Br 8, X = I 9; 75-9(2)\% yields). Complexes 7 and 8 undergo tigand redistribution in wet CH(2)C1(2) solutions giving the EZn(NCNPh2)4(H2O)(2)11Zn(2)(p-X)(2)X41 (X = Cl 10, Br 11) species that were characterized by 1H NMR, HRESI-MS, and X-ray diffraction. Halide abstraction from 1-3 by the action of AgCF3SO3 or treatment of Zn(CF3SO3)(2) with NCNR2 (R-2 = Me-2, C5H10) leads to labile complexes [Zn(CF3SO3)(2)(NCNR2)(3)1 (R-2 = Me-2, 12; C5H10, 1(3)). Crystallization of 12 from wet CH2C12 or from the reaction mixture gave (Zn(NCNMe2)(3)(H20)21(SO3CF3)2 (12a) or EZn(CF(3)S0(3))2(NCNMe2)21. (12b), whose structures were determined by X-ray diffraction. The Znil-mediated hydration was observed for the systems comprising ZnX2 (X = CE, Br, I), 2 equiv. NCNR2 (R2 = Me2, C5I-110, P(h)2) and ca. 40-fold excess of water and conducted in acetone at 60 C (R-2 = Me-2, C5H10) or 80 C (R-2 = Ph-2) in closed vials, and it gives the urea complexes EZnX2\0C(NR2)NH2\1 (R2 = Me2, X = Cl 1(3), X = Br 14, X = I 15; R = C5I-110, X = Cl 16, X = Br 17; X = I 18; R2 = Ph2, X = Cl 19, X = Br 20, X = I 21; 57-81\%). In contrast to the Znii-mediated hydration of conventional nitrites, which proceeds only in the presence of co-catalyzing oximes or carboxamides, the reaction with cyanamides does not require any co-catalyst. Complexes 1-9, 12-19 were characterized by H-1, C-13\1H\ NMR, IR, HRESI-MS, and X-ray crystallography (for 1-3, 8, 9, 1(3)-15, and 17), whereas 20 and 21 were characterized by HRESI+-MS and 1H and 1(3)C\1H\ NMR (for 20). The structural features of the cyanamide complexes 1, 2, 7, and 8 were interpreted by theoretical calculations at the DFT level. |
