Advances in vanadium, niobium and tantalum carbonyls

Niobium and Tantalum

“…Both oxidized and reduced derivatives of [M(CO) 6 ] have been studied; for example, the "highly reduced" carbonyls [M(CO) 5 ] 3~ have been described by Ellis. 39 Both niobium and tantalum complexes [Na(DIGLYME) 2 ] [M(CO) 6 ] can be smoothly reduced with sodium in liquid NH 3 to provide unstable Na 3 M(CO) 5 , which is metathesized to a f f o r d shock-sensitive, explosive Cs 3 M(CO) 5 in moderate yields.…”

“…39 Both niobium and tantalum complexes [Na(DIGLYME) 2 ] [M(CO) 6 ] can be smoothly reduced with sodium in liquid NH 3 to provide unstable Na 3 M(CO) 5 , which is metathesized to a f f o r d shock-sensitive, explosive Cs 3 M(CO) 5 in moderate yields. 11 These species are subject to electrophilic attack, for example, the in situ treatment of the trisodium salt with Ph 3 SnCl provides [Et 4 26 and tantalum.…”

“…11 These species are subject to electrophilic attack, for example, the in situ treatment of the trisodium salt with Ph 3 SnCl provides [Et 4 26 and tantalum. 25 The niobium analogue has been obtained, albeit irreproducibly and in low yield, by 5 Cs 3 M(CO) 5 …”

“…However, when the [r|-C 5 Me 5 ]~ complex Cp*TaCl 4 is reduced under similar conditions (1 atm CO, THF), monomeric Cp*TaCl 2 (CO) 2 (THF) is isolated. 88 The M" oxidation state is especially rare for organometallic compounds o f niobium and tantalum, but M 1 1 organometallics are accessible by reducing M 1 1 1 carbonyl precursors.…”

“…The reductive coupling of CNR ligands has also been observed. When CNBu 1 reacts with Nb 2 Cl 6 (SMe 2 ) 3 (Nb=Nb), two cluster species can be isolated, trinuclear Nb 3 Cl 8 (CNBu t ) 5 (5) and dinuclear Nb 2 Cl 6 (CNBu ! ) 6 (6), in a ratio that is highly condition dependent.…”