Structural and Magnetic Studies of the Tris(cyclopentadienyl)manganese(II) “Paddle-Wheel” Anions [Cp3−n(MeCp)nMn]− (n=0–3, MeCp=C5H4CH3, Cp=C5H5)

Structural characterization of potassium salts of the decamethylmanganocene anion Cp*2Mn. Dalton Trans 2019;48:17078-17082. [PMID: 31701989 DOI: 10.1039/c9dt03551f]

For the first time the crystal structure of a permethylated metallocene anion has been obtained. The 17 valence electron complex decamethylmanganocene Cp*₂Mn is reduced by molten potassium in THF to its extremely air-sensitive anion [Cp*₂Mn]^-. The potassium salt [K(THF)₂]⁺[Cp*₂Mn]^- crystallizes upon cooling from hot THF and forms infinite polymeric chains exhibiting strong KC contacts. In the presence of 18-crown-6 the polymeric structure is broken up. Crystals of [K(18-crown-6)(THF)₂]⁺[Cp*₂Mn]^- were obtained upon slow cooling from THF to -80 °C displaying well separated cations and anions.

Structural diversity in pyridine and polypyridine adducts of ring slipped manganocene: correlating ligand steric bulk with quantified deviation from ideal hapticity

We have synthesized several new manganocene-adduct ([Cp2Mn(L)] = 1-L) complexes using pyridine and polypyridine ligands and report their molecular structures and characterization data. Consistent with other molecules in this class [(ηx-Cp)2MnLn] or [(ηx-Cp)2Mn(L-L)] (n = 1, 2; x = 1, 3, or 5), the manganese-cyclopentadienide interaction deviates from the classical ηx interactions (x = 3 or 5). Such deviations have been ascribed to steric factors and often called non-ideal hapticity. However, there is no quantification of this non-ideal hapticity and thus it is difficult to evaluate the extent of ring slippage or assign hapticity. Furthermore, the hypothesis that non-ideal hapticity in high-spin MnII complexes is induced by steric interactions has not been systematically evaluated. Therefore, we report herein a quantified scale for deviation from ideal hapticity between zero (ideal η5 interaction) and one ("η1" interaction). This quantified deviation from ideal hapticity has an empirical relationship with the ligand's steric properties, which strongly supports the premise that steric interactions cause the deviations in ionic M-Cp interactions.

Addition of pnictogen atoms to chromium(ii): synthesis, structure and magnetic properties of a chromium(iv) phosphide and a chromium(iii) arsenide

Chromium(ii) chloride reacts with LiCp* (Cp* = C₅Me₅) and LiE (SiMe₃)₂ (E = P or As) to give the chromium(iv) phosphide [(η⁵-Cp*Cr)(μ₃-P)]₄ (1) or the chromium(iii) arsenide [(η⁵-Cp*Cr)₃(μ₃-As)₂] (2), respectively.

Reactions of Cp2M (M = Ni, V) with dilithium diamido-aryl reagents; retention and oxidation of the transition metal ions

The reactions of dilithium 1,2-diamidobenzene, [1,2-(HN)2C6H4]Li2 (L(1)H2)Li2, and dilithium 1,8-diamidonaphthalene, [1,8-(NH)2C10H6]Li2 (L(2)H2)Li2, with Cp2Ni and Cp2V have been used to obtain the new complexes (L(2)H2)2Ni{Li(THF)2}2 (3), (L(2)H2)3V{Li(THF)2}3 (4) and (L(1)H2)6Ni6·{[(L(1)H2)3(L(1)H)3Ni6Li(THF)](2-)·2[Li(THF)4](+)} (5), in which retention or oxidation of the initial metal(ii) centre is observed. Whereas 3 and 4 contain one transition metal ion within ion-paired structures, 5 has a complicated co-crystalline composition which contains octahedral Ni6-cages constructed from six square-planar (16e) Ni(II) centres.

The redox effect of the [1,2-(NH)2C6H4]2- ligand in the formation of transition metal compounds

Reactions of the [1,2-(NH)(2)C(6)H(4)](2-) dianion (LH(2)(2-)) with Cp(2)M(II) (M = V, Mn) lead to complete or partial oxidation of the metals (M), giving the V(III) compound [(η(5)-Cp)(LH(2))(2)VV(LH(2))](-)[Li(THF)(4)](+) (1) and Mn(II)(4)Mn(III)(2) oxo cage [Mn(6)(LH(2))(6)(μ(6)-O)(THF)(4)] (2).

Stepwise nucleophilic substitution of manganocene, syntheses and structures of the dimer [CpMn(hpp)]2and the unusual manganate cage [LiMn(hpp)3]2(hppH = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2,a]pyrimidine)

While the nucleophilic substitution reaction of manganocene [Cp(2)Mn] with Li(hpp) (1 : 1 equivalents) gives the neutral dimer [CpMn(hpp)]2 (1), further substitution of the Cp ligands leads to the unusual dimeric manganate cage compound [LiMn(hpp)3]2 (2), generated by the dimerisation of a simple tris-organomanganate monomer.