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 [N i-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) prov ided insight into the interactions of the substrates with the dinickel cent er. In 1, the methylurea molecule coordinates to the dinickel complex throu gh its carbonyl oxygen atom. Complex 2 has a similar geometry, with the thi ourea molecule bound to a nickel ion through its sulfur atom. When the urea substrates are heated in the presence of the hydroxide-bridged,dinickel co mplex, N-methylurea and N,N-dimethylurea react to form methylammonium cyana te and dimethylammonium cyanate, respectively. After long reaction times, t hiourea reacts similarly, producing ammonium thiocyanate. The other substra tes are unreactive. These results indicate that the dinickel complex promot es the elimination of alkylamines from urea substrates to form cyanate but cannot effect the direct hydrolysis of such substrates.