E₄ Transfer (E=P, As) to Ni Complexes

Abstract

The use of [Cp′′2Zr(η1:1‐E4)] (E=P (1 a), As (1 b), Cp′′=1,3‐di‐tert‐butyl‐cyclopentadienyl) as phosphorus or arsenic source, respectively, gives access to novel stable polypnictogen transition metal complexes at ambient temperatures. The reaction of 1 a/1 b with [CpRNiBr]2 (CpR=CpBn (1,2,3,4,5‐pentabenzyl‐cyclopentadienyl), Cp′′′ (1,2,4‐tri‐tert‐butyl‐cyclopentadienyl)) was studied, to yield novel complexes depending on steric effects and stoichiometric ratios. Besides the transfer of the complete En unit, a degradation as well as aggregation can be observed. Thus, the prismane derivatives [(Cp′′′Ni)2(μ,η3:3‐E4)] (2 a (E=P); 2 b (E=As)) or the arsenic containing cubane [(Cp′′′Ni)3(μ3‐As)(As4)] (5) are formed. Furthermore, the bromine bridged cubanes of the type [(CpRNi)3{Ni(μ‐Br)}(μ3‐E)4]2 (CpR=Cp′′′: 6 a (E=P), 6 b (E=As), CpR=CpBn: 8 a (E=P), 8 b (E=As)) can be isolated. Here, a stepwise transfer of En units is possible, with a cyclo‐E42− ligand being introduced and unprecedented triple‐decker compounds of the type [{(CpRNi)3Ni(μ3‐E)4}2(μ,η4:4‐E′4)] (CpR=CpBn, Cp′′′; E/E′=P, As) are obtained.

Cobalt‐Mediated [3+1] Fragmentation of White Phosphorus: Access to Acylcyanophosphanides

“…The P1−P2 and P2−P3 bond lengths (2.1961(1) and 2.207(1) Å, respectively) fall within the range of P−P single bonds (∑ r PP 2.22 Å), while the shorter P3−P4 bond (2.1355(1) Å) implies the retention of significant double bond character [21] . Similar discrepancies between P−P bond lengths have been observed in previous prismane‐derived complexes [28b,d,e] . This suggests that bonding of the polyphosphorus ligand in 5 a is best described as a localized Co1−P1 σ‐bond, with the P3−P4 unit engaging in π‐coordination to the cobalt center.…”

Homo- and heterobimetallic transition metal cluster derived from [Cp*Fe(η5-E5)] (E = P, As) – unprecedented structural motifs of the resulting polypnictogen ligands

“…29 The homotrimetallic cage complexes can be described as well as distorted cubanes consisting of two staggered tetragons (Fe3-E2-Fe1-E5 and E1-E3-E4-Fe2). Surprisingly, in 1-Ni, a P 2 unit is extruded from the former P 5 ring and a cyclo-P 3 ring is formed representing a rare structural motif of the polyphosphorus ligand, which was structurally characterised as a coordination compound of Ag + in 3-Ag, and supported by 31 P NMR spectroscopy (Fig. 4, vide infra).…”

“…Column chromatography was not possible for 1-Mn, which was attributed to the air and moisture sensitivity of 1-Mn. Complex 1-Mn was, however, synthesised selectively as monitored by 31 P NMR spectroscopy (δ( 31 P) = −38.4 ppm), but a second (minor)not yet identifiedspecies is also visible in the 31 P NMR spectrum (δ( 31 P) = −34.3 ppm). ‡ Due to a very similar solubility of 1-Mn and the by-product, their separation by crystallisation is extremely difficult.…”

“…S22-S24, see ESI †), which shows that the in situ generation method is also selective. According to 31 P NMR spectroscopy in these ‡ The yield in percentage cannot be determined, as the number of P atoms within the by-product is unknown.…”

“…[Cp*Fe(η 4 -P 5 )] 2− with 0.5 eq. [Cp′′′Ni(µ-Br)] 2 , another product is formed exhibiting a broad resonance in the 31 P NMR spectrum (δ/ppm = 35.8) and no signals for 1-Ni are observed. So far, a structural elucidation of this product and further spectroscopic insight were not possible, regardless of numerous attempts.…”