Metathesis Reactions of the super-Prussian Blue Systems [(Me3Sn)3M(CN)6] (M=Co, Ir) with, inter alia, Tetrapropylammonium (and -phosphonium) Ions: Crystal Structures of [(nPr4P)(Me3Sn)2Co(CN)6·2H2O] and [(nPr4N)(Me3Sn)2Ir(CN)6·2H2O

Abstract

Tetrapropylammonium and -phosphonium ions, nPr4E+, react readily with the polymeric super-Prussian blue derivatives [(Me3Sn)3M(CN)6] (M=Co, Ir), which are built up of infinite [–M–CN–Sn–NC–] chains, affording the dimorphic supramolecular assembly [(nPr4E)(Me3Sn)2M(CN)6·2H2O]. All representatives of the latter type are devoid of any extended [–M–CN–Sn–NC–] backbones. The single-crystal X-ray structures of 1a-P (E=P; M=Co) and 3a (E=N; M=Ir) document new examples of either modification. While Me4N+ and Et4N+ ions do not form sufficiently insoluble, R4N+-containing assemblies, nBu4N+ and nPen4N+ give rise to similar (i.e., R4N:Me3Sn=1:2) products as nPr4N+. The slightly modified super-Prussian blue system [{Me2Sn(CH2)3SnMe2}1.5Co(CN)6], 4, reacts with nPr4NBr to yield the assembly [(nPr4N){Me2Sn(CH2)3SnMe2}Co(CN)6·2H2O], 4a, the powder XRD and solid-state NMR spectra of which strongly resemble those of 3a (with two cis-oriented CNSn(Me3)OH2 ligands). In the absence of suitable single crystals, in particular in the case M=Ir, powder XRD- and multinuclear solid-state NMR results have been carefully examined in view of specific similarities with already established structural patterns. The unexpected dimorphism of 1a, which has been described most recently for M=Co, could now also be confirmed for M=Ir. The experimental results of the present study in total indicate that the superiority of coordinative N→Sn bonds over O→Sn bonds, in combination with O–H···N≡C hydrogen bridges, decreases, in the presence of R4E+ ions, stepwise with the size of R (i.e., from methyl to n-propyl) and of M (i.e., Co vs Ir).