Synthesis and X-ray structures of silver and gold guanidinate-like complexes. A Au(II) complex with a 2.47 ? Au–Au distance

The structures of the tetranuclear silver(I), [Ag4(hpp)4], and the dinuclear gold(II), [Au2(hpp)2Cl2], (hpp = 1,3,4,6,7,8-hexahydro-pyrimido[1,2-a] pyrimidinate) guanidinate-like bases are reported and show a silver–silver distance of 2.8614(6)? and a gold–gold distance of 2.4752(9)?, the shortest Au–Au bond heretofore reported.