The title compound was prepared upon irradiation of acetonitrile solutions of the readily available hexacarbonyl [MoReCp(μ-H)(μ-PCy)(CO)]. The acetonitrile ligand in this compound could be replaced easily by donor molecules or displaced upon two-electron reduction. In most cases, the substitution step was followed by additional processes such as insertion into the M-H bonds, E-H bond cleavage, H elimination, and other transformations.

An efficient synthetic route for the preparation of the title anions was implemented, and it involved two-electron reduction of iodide-bridged [MMoCp(μ-I)(μ-PR 2 )(CO) 5 ] (Cp = cyclopentadienyl) complexes by using Na(Hg). Reaction of these anions with (NH 4 )PF 6 (in THF) and ClSnPh 3 (in MeCN) gave [MMoCp(μ-H)(μ-PR 2 )(CO) 5 (NH 3 )] and [MoReCp(μ-PCy 2 )(SnPh 3 )-(CO) 5 (NCMe)] (Cy = cyclohexyl), respectively, with incorporation [a]

N,N′-Phosphinoguanidinate Al compounds rearrange under mild conditions to phosphinimine-amidinato derivatives via an unprecedented carbodiimide de-insertion followed by [3+2] cycloaddition.

The ability of the title anion to act as an acceptor of simple donors and to participate in EH bond activation processes (E = p-block element) was analyzed by examining its reactions with PPh2H, HSPh and HCC(p-tol). The sodium salt of this anion (1-Na) reacted with PPh2H to give the electron-precise derivative Na[MoReCp(-PCy2)(CO)5(PPh2H)], with the added ligand trans to the PCy2 group. The latter reacted with (NH4)PF6 to give the hydride-bridged derivative mer-[MoReCp(-H)(-PCy2)(CO)5(PPh2H)], which was dehydrogenated photochemically to give first the known compound [MoReCp(-PCy2)(-PPh2)(CO)5], and then the new complex [MoReCp(-O)(-PCy2)(-PPh2)(CO)3], with a strongly asymmetric bridging oxide ligand (MoRe = 2.8640(6) Å). The reaction of 1-Na with HSPh involved protonation and ligand addition to give the thiol complex [MoReCp(-H)(-PCy2)(CO)5(HSPh)], which underwent spontaneous dehydrogenation to give the thiolate derivative [MoReCp(-PCy2)(-SPh)(CO)5] (MoRe = 2.9702(8) Å), having a quite puckered central MoPReS ring. The latter rearranged photochemically to yield [MoReCp(-PCy2)(-SPh)(1-CO)(CO)4], which displays a Re(CO)4 fragment and reverts thermally to the starting isomer; density functional theory calculations on these and related [MoReCp(-PCy2)(-X)(CO)5] complexes (X = PPh2, Cl) revealed that the structure with the puckered central ring is strongly disfavored for bulky X groups. Compound 1-Na reacted with (ptolyl)acetylene to give complex Na[MoReCp(-PCy2)(CO)5{ 2 -HC2(p-tol)}], with an alkyne ligand  2 -bound to Re and positioned cis to the PCy2 group. Protonation of the latter gave the alkenyl complex [MoReCp{- 1 : 2 -C(p-tol)CH2}(-PCy2)(CO)5], which rearranged spontaneously via alkenyl-carbonyl coupling and different 1,2-H shifts to give [MoReCp{- 2 : 2 C,O-C(ptol)CHC(O)H}(-PCy2)(CO)4], with a formyl-alkenyl ligand O-bound to Re through its formyl fragment (MoRe = 2.970(1) Å).