A complete series of W2(hpp)4Cln (n=0,1,2) compounds

Full structural characterization of the first homologous series of ditungsten paddlewheel compounds having an electronic configuration of the type σ2π4δx, x=2,1,0, and W–W bond orders of 4, 3.5 and 3, respectively, has been accomplished with the guanidinate-type ligand hpp (hpp = the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine); the lengthening in bond distances from W2(hpp)4·2NaHBEt3 to W2(hpp)4Cl to W2(hpp)4Cl2 is 0.05 Å for each step.