Towards the chemical control of molecular packing: syntheses and crystal structures of three trans-[NiL4(NCS)2] complexes

Three nickel(II) isothiocyanato complexes of the formula trans-[NiL4(NCS)2] (L = ethylisonicotinate, methylisonicotinate and 4-benzoylpyridine) have been prepared: [Ni(ethylisonicotinate) 4(NCS)2] (I), [Ni(methylisonicotinate)4(NCS)2] (II) and [Ni(4-benzoylpyridine)4(NCS)2] (III). All three complexes are monomeric and have a distorted octahedral geometry around NiII. Despite their apparent molecular similarity, the crystal density of (III) (1.454 g cm 3) is significantly higher than that of (I) and (II) (both 1.408 g cm 3), suggesting that the molecular packing is most efficient in (III). A study of the molecular Hirshfeld surfaces, together with density functional theory (DFT) calculations, provide insights into the origin of the molecular packing features, and it is suggested that the greater crystal density of (III) results from smaller intermolecular electrostatic repulsions

Interpretation of the terminal v(co) spectra of some M5 transition metal carbonyl clusters

The n(CO) spectra of 31 M5 transition metal carbonyl clusters are interpreted in terms of the spherical harmonic and tensor harmonic models. It seems that the former is that which is generally applicable but that the splittings of the (spherical) P mode are larger than had previously been considered indicative of this model. An explanation in terms of the cluster asymmetry is suggested