Eilis A. Harron

Syntheses and magnetic properties of hexanuclear [Cp2Mn3(L1)4]2 and octanuclear [Mn8(L2)12(μ4-O)2] (L1 = 2-HNC5H5N, L2 = 2-NH-3-Br-5-MeC5H3N, Cp = C5H5)

The reactions of manganocene, Cp2Mn, with 2-aminopyridine (L1H) or 2-amino-3-bromo-5-methylpyridine (L2H) give the novel hexanuclear and octanuclear Mn(II) amido cage compounds [Cp2Mn3(L1)4]2 (1) and [Mn8(L2)12(mu 4-O)2] (2); magnetic measurements on which provide a rare insight into the magnetic properties of amido-bridged metal clusters.

Applications of manganocene in the synthesis of Mn(II) amide and imide cages

The reactions of manganocene, Cp2Mn (Cp = C5H5), with 2-aminopyrimidines give similar, octameric amido/imido cage complexes of general formulae [{CpMnNHR}{MnNR}]4 [R = 4,6-Me2pm (1a), 4-MeO-6-Mepm (1b), 4,6-(MeO)2pm (1c); pm = pyrimidinyl]. The structures of these complexes can be visualised as being composed of central Mn4N4 imido cubane units that are coordinated at their peripheries by four [CpMnNHpm] monomers. In contrast, less acidic 2-aminopyridine (2-NH2py) and 8-aminoquinoline (8-NH2quin) are only singly deprotonated under similar conditions, giving the unusual hexanuclear amido complex [Cp2Mn3(NHpy)4]2 (2) and the dimer [CpMn(μ-8-HNquin)]2 (3). N,N′-Dibenzylethylenediamine [(BnNHCH2)2] only forms the simple adduct [(η1-Cp)(η5-Cp)Mn{(BnNHCH2)2}] (4) (Bn = CH2Ph) with Cp2Mn, in which no deprotonation of the organic acid has occurred. The X-ray structures of the new complexes 1b–c, 3 and 4 are reported (1a and 2 having been communicated previously).

Synthesis and structure of [{As2(NCy)4}2Li4], containing an imido As(III) dianion

Reaction of [As(NMe2)3] with CyNH2 (1∶1 equivalents), followed by the addition of [CyNHLi] (1 equivalent) gives the heterobimetallic cage complex [{As2(NCy)4}2Li4], the first example of a complex containing a imido As(III) anion; the missing link in a series of group 15 anions of the type [{E2(NCy)4}]2– (E = Bi, Sb and P).

Association and fragmentation of imidotin(II) complexes containing donor-functionalised peripheries; towards new three-dimensional main group metal ligands

Structural studies of a series of tin(II) imido cubanes, [SnNR]4, containing donor-functionalised organic substituents (R), have allowed the systematic investigation of the factors controlling and affecting association of these architypal tin(II) complexes in the solid state. In addition to steric shielding of the Sn4N4 cores, intra- and inter-molecular O and N donation modifies or curtails association via Sn⋯Sn interactions, and can even facilitate fragmentation of the cubane cores.

Geometric control of cage architecture; observation of ligand-selective behaviour in the structures of [{As2(NCy)4}2M4] (M = Na, Cu; Cy = C6H11)

The structure of [{As2(NCy)4}2Cu4] reveals a dramatic change in the metal coordination mode compared to that found in the Sb analogue [{Sb2(NCy)4}2Cu4], resulting in the distortion of the Cu4 core from a square-planar to a butterfly shape and providing the first illustration of ligand-selective cage modification in such heterobimetallic species; in contrast the square-planar Na4 arrangement found in [{Sb2(NCy)4}2M4] (M = Na, Cu, Ag) is retained in [{As2(NCy)4}2Na4].

Nucleophilic addition to a Sn(II) imido cubane, [SnNR]4; a new route to heteroleptic stannates

Nucleophilic addition to Sn(II) imido cubanes provides a novel route to heteroleptic stannates, as exemplified by the formation of [{Sn(NHmmp)(OtBu)2}K·thf]2 (2) and [{Sn(MeNCH2CH2NMe)(NHmmp)}Li]∞ (3) from the in situ reactions of the imido Sn(II) cubane [Sn(Nmmp)]4 (1) (mmp = 2-MeO-6-MeC6H3) with tBuOK and [MeN(Li)CH2CH2(Li)NMe]. This pathway demonstrates that Sn(II) imido cubanes can act as synthons for their aza-stannylene constituents, RNSn:.

Effects of meta-substitution on aggregation in the cubanes [SnNR]4{R = [2-Me-5-MeOC6H3], [2,5-(MeO)2C6H3] and [3,5-(MeO)2C6H3]}

An investigation of the solid-state X-ray structures of the cubanes [SnN{2-Me-5-MeOC6H3}]4, (1), [SnN{2,5-(MeO)2C6H3}]4, (2), and [SnN{3,5-(MeO)2C6H3}]4, (3), containing meta-MeO substituents on their aromatic groups, shows that unprecedented modes of intra- and intermolecular association occur. In 1, novel co-ordination of two of the cubane Sn2N2 faces by thf ligands is found, the first observation of Lewis base solvation by a separate donor ligand in this class of complexes. In 2, dimerisation of cubane units occurs via a combination of Sn⋯Sn, Sn⋯O and arene⋯Sn interactions, whereas in 3, an unusual ‘sinusoidal’ pattern of aggregation is seen.

Synthesis and structure of [Sn9(Ndmp)7(HNdmp)2O2], containing a bidentate double-cubane oxo fragment (H2Ndmp= 2-amino- 4,6-dimethoxypyrimidine

The reaction of Sn(NMe2)2 with H2Ndmp (H2Ndmp = 2-amino-4,6-dimethoxypyrimidine) and H2O (ca. 4∶4∶1 equivalents, respectively) gives the cage complex [Sn9(Ndmp)7(HNdmp)2O2] 1, containing an oxo double-cubane fragment [Sn7(Ndmp)6O2] coordinated to a neutral (HNdmpSn)2(μ-Ndmp) unit; 1 is the largest imido Sn(II) complex so far characterised.