Coupling reactions of the tetranuclear rectangular clusters Mo4Cl8(PR3)4. Phosphine ligand abstraction and formation of the condensation products [Mo4Cl8(PR3)2]x

Reaction of the tetrameric clusters Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 4/ (PR/sub 3/ = PEt/sub 3/, P(n-Pr)/sub 3/, P(n-Bu)/sub 3/, and PMe/sub 2/Ph) with Mo(CO)/sub 4/Cl/sub 2/, or more conveniently with Mo(CO)/sub 6/, in refluxing chlorobenzene leads to phosphine abstraction and formation of the condensation products (Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 2/)/sub x/. Evidence obtained from reactivity and spectroscopic data indicates that these condensation products all have the same basic structure and retain the rectangular cluster units derived from Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 4/ as essential components. Extended Mo-Mo bonding between the coupled tetrameric units is concluded to be unlikely. Because the compounds are crystalline and exhibit significant solubility in noncoordinating solvents, their formulation as dimers of tetramers, (Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 2/)/sub 2/, is preferred over the alternative formulation as polymers, (Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 2/)/sub infinity/. 23 references, 3 figures, 2 tables.