Intermediates in the condensation process of [MS4](2-) (M = Mo, W) to polythiometalates, in the presence of alkyl halides, had not been reported prior to our communication of [PPh4][WS3(SEt)] (Boorman, P. M.; Wang, M.; Parvez, M. J. Chem. Sec., Chem. Common. 1995, 999-1000). We now report the isolation of a range of related compounds, with 1 degrees, 2 degrees, and 3 degrees alkyl thiolate ligands, including one Mo example. [PPh4][WS3(SR)] (R = Bu-i (1), Pr-i (2), Bu-t (3), benzyl (5), allyl (6)) and [PPh4][MoS3((SBu)-Bu-t)] (4) have been isolated in fair to good Yields from the reaction of [PPh4](2)[MS4] With the appropriate alkyl halide in acetonitrile and subjected to analysis by X-ray crystallography. Crystal data are as follows: for 1, triclinic space group P (1) over bar (No. 2), a = 11.0377(6) Angstrom, b = 11.1307(5) Angstrom, c = 13.6286(7) Angstrom, alpha = 82.941(1)degrees, beta = 84.877(1)degrees, gamma = 60.826(1)degrees, Z = 2; for 2, monoclinic space group P2(1)/c (No. 14), a = 9.499(6) Angstrom, b = 15.913(5) Angstrom, c = 18.582(6) Angstrom, beta = 99.29(4)degrees, Z = 4; for 3, monoclinic space group P2(1)/n (No. 14), a = 10.667(2) Angstrom, b = 17.578(2) Angstrom, c = 16.117(3) Angstrom, beta = 101.67(1)degrees, Z = 4; for 4, monoclinic space group P2(1)/n (No. 14), a = 10.558(3) Angstrom, b = 17.477(3) Angstrom, c = 15.954(3) Angstrom, beta = 101.18(2)degrees, Z = 4; for 5, monoclinic space group P2(1)/n (No. 14), a = 16.2111(9) Angstrom, b = 11.0080(6) Angstrom, c = 18.1339(10) Angstrom, beta = 111.722(1)degrees, Z = 4; for 6, triclinic space group P (1) over bar (No. 2), a = 9.4716(9) Angstrom, b = 10.4336(10) Angstrom, c = 14.4186(14) Angstrom, alpha = 100.183(2)degrees, beta = 90.457(2)degrees, gamma = 91.747(2)degrees, Z = 2. Structures 3 and 4 are isomorphous, and 1 exhibits disorder about the tertiary carbon. 6 has been shown to exhibit fluxionality in solution by variable-temperature H-1 NMR studies, and an allyl migration mechanism is implicated in this process. The kinetics for the reaction of [WS4](2-) and EtBr were measured and suggest an associative nucleophilic substitution (S(N)2) mechanism. The decomposition of the [WS3(SEt)](-) ion is shown to be second order with respect to this ion, suggesting the formation of a transient binuclear intermediate. M-S bond cleavage is the predominant step in decomposition of 1-6 to yield alkyl sulfides, alkyl thiols, and polythiometalates such as [PPh4](2)[M3S9]. In contrast, reactions of [PPh4](2)[WOxS4-x] (x = 1, 2) with (BuBr)-Bu-t result in the additional decomposition product of isobutene, presumably by C-S bond cleavage and beta -hydrogen transfer. Interestingly, the reaction of [PPh4](2)-[WOS3] with BzCl yields 5 as the only isolable W thiolate species.