Halide abstraction from the chlorotris(dialkyldithiocarbamato)molybdenum(IV) Complexes MOCl(S2CNR2)(3) (R = Et. Me) with silver triflate produces the diamagnetic dimeric complexes [Mo-2(S2CNR2)(6)](OTf)(2) in good yield. The crystallographically determined structure of the diethyldithiocarbamato complex indicates that the dimer consists of two pentagonal bipyramids sharing an axial edge, with a Mo-Mo separation (2.8462(8) Angstrom) indicative of a metal-metal bond. A qualitative analysis of the bonding indicates that this bond is of order 2 and consists of one normal sigma bond and one relatively weak "skewed pi" interaction. The dimers [Mo-2(S2CNR2)(6)](OTf)(2) react with a variety of reagents to give monomeric seven-coordinate complexes, including the new cationic molybdenum(IV) complex [Mo(PMe2Ph)(S2CNEt2)(3)](OTf). which has been structurally characterized, Kinetic studies of the reaction of [Mo-2(S2CNEt2)(6)](OTf)(2) with halides indicate the presence of competing dissociative and associative substitution pathways. although neutral donors may react by different mechanisms.