Decomposition of alkyl-substituted urea molecules at a hydroxide-bridged dinickel center

The interactions between N-methylurea, N,K-dimethylurea. N,N-dimethylurea, tetramethylurea, and thiourea and the hydroxide-bridged dinickel complex [Ni-2(mu -OH)(mu -H2O)(bdptz)(H2O)(2)](OTs)(3) were investigated. Structural characterization of [Ni-2(mu -OH)(mu -H2O)(bdptz)(Me-urea)(CH3CN)](ClO4)(3) (1) and [Ni-2(mu -OH)(mu -H2O)(bdptz)-(thiourea)(CH3CN)](ClO4)(3) (2) provided insight into the interactions of the substrates with the dinickel center. In 1, the methylurea molecule coordinates to the dinickel complex through its carbonyl oxygen atom. Complex 2 has a similar geometry, with the thiourea molecule bound to a nickel ion through its sulfur atom. When the urea substrates are heated in the presence of the hydroxide-bridged,dinickel complex, N-methylurea and N,N-dimethylurea react to form methylammonium cyanate and dimethylammonium cyanate, respectively. After long reaction times, thiourea reacts similarly, producing ammonium thiocyanate. The other substrates are unreactive. These results indicate that the dinickel complex promotes the elimination of alkylamines from urea substrates to form cyanate but cannot effect the direct hydrolysis of such substrates.