Packing interactions in the crystal structures of a series of cis-M(CNAr)(2)Cl(2) complexes (M = Pt, Pd; Ar = substituted phenyl) were examined and correlated with the luminescence properties of the Pt complexes. The structures of the PhNC and p-tolyl isocyanide complexes exhibit extended chains of metallophilic interactions with M···M distances of 3.24-3.25 and 3.34 Å, respectively, with nearly isostructural Pt and Pd compounds. Both structure types contain void channels running parallel to the M···M chains. The channels are 3-4 Å wide and vacant for the phenyl structures, while those in the p-tolyl structures are up to 7.6 Å wide and contain water. These channeled structures are stabilized by a combination of metallophilic bonding and aryl π-π stacking interactions. The Pt structure with 4-F substituents also features extended Pt···Pt chains, but with longer 3.79 Å distances alternating with shorter 3.37 Å contacts. Structures with 4-CF(3) and 4-OMe substituents exhibit mostly isolated dimers of M···M contacts. In complexes with 2,6-dimethylphenyl isocyanide, steric hindrance precludes any short M···M contacts. The primary effect of aryl substitution is to provide alternative packing motifs, such as CF(3)···π and CH(3)···π interactions, that either augment or disrupt the combination of metallophilic contacts and π-π stacking needed to stabilize extended M···M chains. Differences in the Pt and Pd structures containing 4-F and 4-OMe substituents are consistent with a higher driving force for metallophilic interactions for Pt versus Pd. The M-C and M-Cl bond distances indicate a slightly higher trans influence for aryl isocyanides bound to Pt versus Pd. The three extended Pt···Pt chain structures display luminescence assignable to (dσ*→pσ) excited states, demonstrating the existence of substantial orbital communication along the metal-metal chains. Face-indexing shows that the preferred crystal growth axis is along the metal-metal chains for the luminescent structures. Variable temperature structural studies showed that both M···M and π-π interactions contract upon cooling. Overall, this study suggests that synergy with π-π and other interactions is necessary to stabilize extended M···M chain structures. Thus, efforts to design functional materials based on metallophilic bonding must consider the full array of available packing motifs.
Two distinct polymorphs of cis-M(CNPh)2Cl2 (M = Pt,Pd) were obtained under different crystallization conditions. One polymorph of each compound contains 3−4 Å-wide, vacant channels stabilized by a synergistic combination of extended metallophilic interactions and ligand π−π stacking, whereas the other polymorph contains no discernible void space and only isolated, longer metal−metal contacts. The channeled polymorphs are favored under faster crystal growth conditions, and face-indexing revealed that the growth axes are along the M···M chains. Although the channels extend the length of a crystal, they do not absorb solvent because of their narrow widths.
The title complex, [MnCl2(C3H7NO)2(H2O)2], was obtained upon dissolution of a dimethoxyethane adduct of MnCl2 in N,N‐dimethylformamide. In the crystal structure, each MnII ion is located on a crystallographic inversion center, coordinated by two Cl [Mn—Cl = 2.53423 (17) Å] and four O [Mn—O = 2.1847 (5) and 2.2199 (6) Å] atoms in a distorted octahedral geometry. The complexes are linked into chains by complementary pairs of O—H...Cl hydrogen bonds. Adjacent chains pack via weaker O—H...Cl interactions or by interdigitation of —NMe2 groups. The H atoms of two symmetry‐related methyl groups are disordered between two orientations in a 0.51:0.49 ratio.
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