Synthesis and Crystal Structure of a “High-temperature” Phase of Li[H2NC(O)NH], the Missing Alkali-Metal Ureate

Abstract

The new salt-like lithium ureate, LiCN2H3O, 1, was synthesized to round up the series of the recently published alkali-metal ureates. Single crystals of 1 were prepared similarly to the previously made ureates of Na-Cs in liquid ammonia. LiCN2H3O crystallizes in the monoclinic space group P21/n with a = 7:5770(9), b = 9:059(1), c = 13:046(2) Å, b = 98:896(2)°, V = 884:8(2)Å3, and Z = 12. The Li+ ions are coordinated by four ureate anions in a distorted tetrahedral manner. As expected, the deprotonation of the urea molecules is reflected by the shape of the anions with two different C-N bond lengths.