Tetranuclear phosphinidine, phosphide, arsenide and oxide anionic clusters of molybdenum and tungsten supported by neopentoxide ligands: Na(18-crown-6)2- [Mo4(OCH2tBu)11PSiMe3], K(18-crown-6)- [M4(OCH2tBu)10(E)] where E = P and As and K(18-crown-6).
Budzichowski, T. A.; Chisholm, M. H.; Folting, K.; Streib, W. E.; Scheer, Manfred