Oxidative addition of the sulfur-sulfur bond of 2,2'-pyridine disulfide (C5H4NS-SC5H4N) with L3W(CO)(3) [L = pyridine, 1/3CHPT; CHPT = cycloheptatriene] in methylene chloride solution yields the seven-coordinate W(II) thiolate complex W(eta (2)-mp)(2)(CO)(3) (mp = monoanion of 2-mercaptopyridine), This complex undergoes slow further oxidative addition with additional pyridine disulfide, yielding W(eta (2)- mp)(4). Reaction of W(eta (2)-mp)(2)(CO)(3) with NO results in quantitative formation of the six-coordinate W(0) complex W(eta (2)-mp)(2)(NO)(2). Reaction of W(eta (2)-mp) (2)(CO)(3) with NO in the presence of added pyridine disulfide yields the seven-coordinate W(II) nitrosyl complex W(eta (2)-mp)(3)(NO) as well as W(eta (2)-mp)(2)(NO)(2) and trace amounts of W(eta (2)-mp)(4). The complex W(eta (2)-mp)(3)(NO) is formed during the course of the reaction and not by reaction of W(eta (2)-mp)(4) or W(eta (2)-mp)(2)(NO)(2) with NO under these conditions. The crystal structures of W(eta (2)- mp)(2)(CO)(3). W(eta (2)-mp)(2)(NO)(2), and W(eta (2)-mp)(3)(NO) are reported.