Alkyneselenolate vs Selenoketenyl Coordination:  Synthesis and Reactivity of [Ir(SeC⋮CC₆H₄Me-4)(CO)(PPh₃)₂]

Abstract

The reaction of [IrCl(CO)(PPh3)2] with LiSeC⋮CR (R = C6H4Me-4) provides [Ir(SeC⋮CR)(CO)(PPh3)2] (1), which undergoes oxidative addition reactions with oxygen, methyl iodide, benzeneselenenyl chloride and bis(4-tolylethynyl)mercury to provide the complexes [Ir(SeC⋮CR)(η2-O2)(CO)(PPh3)2] (2), [Ir(CH3)(SeC⋮CR)I(CO)(PPh3)2] (3), [Ir(CH3)I2(CO)(PPh3)2] (4), [IrCl(SePh)(SeC⋮CR)(CO)(PPh3)2] (5), and [Ir(C⋮CR)(HgC⋮CR)(SeC⋮CR)(CO)(PPh3)2] (6). The complexes 1−3, and 5, and 6 each contain the alkyneselenolate ligand bound to iridium in a monodentate manner through selenium.

Isoselenocarbonyls via acetylenic C–Se activation

“…31 P{ 1 H} NMR (CD 2 Cl 2 , 25 • C, 121.4 MHz): d = 26.2, 25.4 (d × 2, 2 J PP = 20 Hz). MS (ESI + ): m/z (%) 1365(<5) [M + Na] + , 1062 (5) [M − 2CO − PPh 3 + K] + , 841(100) [M − 2PPh 3 + Na] + . Synthesis of cis-3: Compound 2 as prepared above was redissolved in THF (20 mL) and the solution stirred for a further 3 days at which time the solvent was removed and the residue chromatographed (silica gel, −33 • C).…”

“…Templeton et al have reported the synthesis of [(g-C 5 H 5 )(CO) 2 Fe-C≡Mo(CO) 2 {HB(pzMe 2 ) 3 }] from [Mo(≡CCl)(CO) 2 {HB(pzMe 2 ) 3 }] and K[Fe(CO) 2 (g-C 5 H 5 )], 3 whilst we have previously described the first examples of alkynylselenolate complexes in which the ligand coordinates in either a dihapto (g 2 -C,C ) 4 or monodentate (r-Se) mode. 5 There are of course a vast number of metal alkynyl complexes, however the second constituent arising from the alternative cleavage (e), an isoselenocarbonyl linkage, is without precedent. Indeed, no bimetallic selenocarbonyl complexes have been reported.…”

The Odd Bit of Carbon

“…[18] In keeping with the reactions of alkynylselenolates with metal halides, [20] the anionic selenocarbonyl complex reacts with a variety of transition metal halides to afford isoselenocarbonyl bridged bimetallics. In the case of Vaska's complex, whilst an isoselenocarbonyl might be a plausible intermediate, this undergoes subsequent insertion of iridium into the C-Se bond to afford a novel bis(carbido) complex based on an Ir 2 Se 2 tetrahedrane core (Scheme 6).…”

Alkynyl Selenolate Complexes of Iron, Nickel, and Molybdenum

“…We have previously reported the first examples of transition metal complexes of the alkynylselenolate ligand ‘”SeCCR” in two different coordination modes via disparate routes (Scheme ). , …”