Activation of Ligand Reactivity:  Thiolate C−S and Dithiophosphate Ester C−O Heterolyses within a Dimolybdenum(V) System

Abstract

Ligand reactivity was demonstrated for sulfide alkylation, thiolate dealkylation, and dithiophosphate de-esterification within molybdenum(V) dimers. The cationic complex [Mo(2)(NC(6)H(4)Me)(2)(S(2)P(OEt)(2))(2)(&mgr;-O(2)CMe)(&mgr;-SR)(2)](+) was inductively activated toward thiolate C-S and dithiophosphate C-O heterolyses. The dealkylations were studied using anionic nucleophiles, and various reactivity patterns were characterized. The de-esterification of the diethyl dithiophosphate ligands produced complexes containing the rare monoester EtO(O)PS(2)(2)(-) ligand. This ligand's phosphoryl group was poorly nucleophilic but weakly basic. Crystallographic comparisons between the activated cation and the neutral complex [Mo(2)(NC(6)H(4)Me)(2)(S(2)P(OEt)(2))(2)(&mgr;-O(2)CMe)(&mgr;-S)(&mgr;-SMe)] were conducted to delineate structural differences related to the activation. A crystallographic study was also done of the complex [Mo(2)(NC(6)H(4)CH(3))(2)(S(2)P(OEt)(2))(S(2)P(O)OEt)(&mgr;-O(2)CMe)(&mgr;-SEt)(2)], which provided internal comparison of monoester EtO(O)PS(2)(2)(-) and diester (EtO)(2)PS(2)(-) ligand types.

Alkyl Transfer Reactivity in the First Octahedral Isocyanide Complex of Nickel(II)

“…There are only a few precedents for this O−C activation in Ni(II) and Mo(V) complexes, and its relevance in several fields has been recently emphasized, especially in connection with the enzymatic alkyl transfer from and to phosphate esters. , It has been generally proposed that the alkyl group is transferred to the leaving dithiophosphate group to afford neutral O,O ‘ , S -triethyl dithiophosphate: EtSP(S)(OEt) 2 .…”

Alkylation of a Dimolybdenum SO Bridge, Subsequent Reactions, and Characterization of the Thioperoxide Bridge

“…These secondary reactions parallel those from prior studies, which showed that bis (thiolate-bridged) cations of general formula R 0 S{Mo 2 }-SR 0+ were subject to nucleophilic attack via two pathways, as illustrated by a and b below. 36 In path a, the nucleophile attacked either of the bridge thiolates at the R-carbon, cleaving the C-S bond to produce a neutral sulfide product R 0 S{Mo 2 }S, 2; this was a reversible equilibrium process. In path b, the nucleophile attacked either dithiophosphate ligand at either of its ethyl groups, cleaving a C-O bond; this was an irreversible de-esterification which gave neutral [Mo 2 (NTo) 2 (S 2 P(OEt) 2 )(S 2 PO(OEt))(μ-O 2 CMe)(μ-SR 0 ) 2 ].…”

“…The NMR spectra also revealed conformational isomers in solution associated with facile inversion at the pyramidal sulfur bridges; these invertomers are common to BnS{Mo 2 }SO, 1, 17 to previously reported R 0 S-{Mo 2 }SR 0+ cations, 36 and to other prior compounds. The sulfur substituent positions are labeled distal (d) or proximal (p) relative to the tolylimido rings as a reference point.…”

Synthesis and Structure of Heterobimetallic Compounds with a Single Thiolato-Bridged Ligand

“…Thus, reaction between CpW(CO) 2 (μ‐SMe)W(CO) 5 ( W−W ) and phosphanes formed CpW(PR 3 )(CO) 2 (μ‐SMe)W(CO) 5 2 while its phosphido‐bridged analogue CpW(CO) 2 (μ‐PPh 2 )W(CO) 5 ( W−W ) gave CpW(CO) 2 (μ‐PPh 2 )W(PR 3 )(CO) 4 ( W−W ) 1c. In addition, compounds with thiols as a ligand are significantly related to catalysts and biological activity 3−8. Many of them are bimetallic complexes 3,4,5a,6,7.…”

“…In addition, compounds with thiols as a ligand are significantly related to catalysts and biological activity 3−8. Many of them are bimetallic complexes 3,4,5a,6,7. As thiols having strong bridging abilities in coordination, enormous numbers of bimetallic compounds containing (μ‐SR) 2 bridges are reported 9.…”