Chemistry of [{Cr(cp)(CO)₃}₂], (cp =η⁵-C₅H₅). Reaction with elemental P₄. A high yield synthesis and crystal structures of [{Cr(cp)(CO)₂}₂(µ-η²-P₂)] and [Cr(cp)(CO)₂(η³-P₃)]

Cyclo-P3 Complexes of Vanadium: Redox Properties and Origin of the 31P NMR Chemical Shift

“…Irrespective of which mechanism is operative, a terminal phosphide could exist en route to the final metal– cyclo -P 3 complex. Most of the known cyclo -P 3 complexes include late metals, − whereas, in contrast, early transition metal analogues are scarce, − ,− probably due to the rarity of low-valent metal fragments capable of reducing the P 4 unit by multiple electrons and the mismatch in orbital energies between the soft phosphorus and these hard transition metal ions . Only recently have high-valent examples of anionic L 3 Nb­(V) cyclo -P 3 complexes (L – = N­[CH 2 t Bu]­(3,5-Me 2 C 6 H 3 ), O­{2,6- i Pr 2 C 6 H 3 }) − , and a neutral vanadium­(V) complex (nacnac)­V­( cyclo -P 3 )­(Ntolyl 2 ) ( 1 ) (nacnac – = [ArNCCH 3 ] 2 CH, tolyl = 4-MeC 6 H 4 ) been reported.…”

“…Most of the known cyclo -P 3 complexes include late metals, − whereas, in contrast, early transition metal analogues are scarce, − ,− probably due to the rarity of low-valent metal fragments capable of reducing the P 4 unit by multiple electrons and the mismatch in orbital energies between the soft phosphorus and these hard transition metal ions . Only recently have high-valent examples of anionic L 3 Nb­(V) cyclo -P 3 complexes (L – = N­[CH 2 t Bu]­(3,5-Me 2 C 6 H 3 ), O­{2,6- i Pr 2 C 6 H 3 }) − , and a neutral vanadium­(V) complex (nacnac)­V­( cyclo -P 3 )­(Ntolyl 2 ) ( 1 ) (nacnac – = [ArNCCH 3 ] 2 CH, tolyl = 4-MeC 6 H 4 ) been reported. Notably, some of these complexes have been shown to readily deliver the [ cyclo -P 3 ] 3– unit to various main group electrophiles and form new tetrahedron allotropes with different pnictogenic elements, such as P and As. ,, …”

Unusual Reactivity of a Cr2P2 Tetrahedral Complex toward Superhydride; Formation of [{CpCr(CO)2}2(μ-PH2)x(μ-H)2-x] (x = 1 and 2) and [〈{CpCr(CO)2}2(μ-PH)〉{(CpCr)2(μ,η1:η1:η5:η5-P5)}]

“…Although the Cr−Cr distance in 2 can be assigned as a slightly elongated single bond (3.104(1) Å) in comparison to those of 1 (3.011(1) Å) and [(CO) 4 CrP(CH 3 ) 2 ] 2 (2.950 Å), the distance in 3 (3.881 Å) falls beyond the range of a bond. The average Cr−P bond distance in 2 (2.269 Å) is slightly shorter than the average bond distances in 3 (2.381 Å, average distances of three independent molecules), 1 (2.409 Å), [Cp 2 Cr 2 (CO) 4 (μ,η 2 -P 2 ){Cr(CO) 5 }] (2.405 Å), [Cp 2 Cr 2 (CO) 4 (μ,η 2 -P 2 ){Cr(CO) 5 } 2 ] (2.411 Å) and in [(CO) 4 CrP(CH 3 ) 2 ] 2 (2.318 Å) . Each chromium atom in 2 and 3 achieves the 18-electron configuration.…”

“…Solvents were dried and distilled under an argon atmosphere prior to use: toluene and THF over Na/benzophenone, hexane over LiAlH 4 , and dichloromethane over P 2 O 5 . [{CpCr(CO) 2 } 2 (μ,η 2 -P 2 )] was prepared according to a modified literature method . NMR spectra were recorded on a Bruker AC 250 ( 1 H, 250.133 MHz; 13 C, 62.896 MHz; 31 P, 101.256 MHz; standard 1 H and 13 C, Me 4 Si, 31 P, 85% H 3 PO 4 ).…”

“…The latter is a general problem in this synthetic field . The synthesis of the complex [{CpCr(CO) 2 } 2 (μ,η 2 -P 2 )] ( 1 ), obtained in 53% yield, was reported by Goh et al Starting from this complex, we tried first to cleave its P−P bond by using superhydride to generate a dianionic complex according to eq 1. Although this reaction pattern is known for disulfur complexes (e.g., [Fe 2 (CO) 6 (μ-S 2 )]), complex 1 undergoes unexpected transformation pathways.…”