(Isocyano Group π‐Hole)⋅⋅⋅[d‐M^II] Interactions of (Isocyanide)[M^II] Complexes, in which Positively Charged Metal Centers (d⁸‐M=Pt, Pd) Act as Nucleophiles

Abstract

Inspection of the X‐ray structures of the newly prepared trans‐[MII(CNXyl)2(DAPT)2]Cl(BF4) (M=Pd, Pt; Xyl=2,6‐Me2C6H3; DAPT=4,6‐diaminopyrimidine‐2(1H)‐thione) complexes and the appropriate Hirshfeld molecular surface analysis allowed the recognition of the previously unknown π‐hole⋅⋅⋅metal interactions between a ligated isocyano group (acting as a π‐hole donor) and the positively charged d8‐PtII and d8‐PdII metal centers (acting as nucleophiles); this is the first identification of π‐hole⋅⋅⋅metal interactions with triple‐bond species. Results of DFT calculations followed by the topological analysis of the electron density distribution within the framework of Bader's theory (quantum theory of atoms in molecules, QTAIM) confirmed the presence of these contacts. The electrostatic surface potential calculations indicated that π‐hole⋅⋅⋅metal contacts are formed upon interaction between the electrophilic isocyano C atom (π‐hole donor) and the nucleophilic dz2 orbital of the metal centers, which act as π‐hole acceptors. Available CCDC data were processed from the perspective of the π‐hole⋅⋅⋅metal interactions with isocyanide ligands, and their analysis disclosed the role of metal nucleophilicity in the corresponding π‐hole acceptor ability.

The halogen bond with isocyano carbon reduces isocyanide odor

“…In the second contact, ∠(C-I•••C) 79.50 (14)°and ∠(I•••C ≡ N) 94.9 (3)°are close to 90°and, accordingly 8 , this interaction cannot be recognized as XB. Previously, we reported a similar interaction pattern for (isocyano group)•••lp 23,24 and (isocyano group)•••πsystem 29 contacts observed for metal-bound CNR; in these systems the isocyano fragment acted as a π-hole donor. We assume that in the case of (CNMes)•IPFB, the longer I•••C contact could also have a contribution of π-hole•••lp interaction involving the π-system of the isocyanide group and lp of the iodine atom.…”

“…Taking into account our general interest in the isocyanide chemistry (for our relevant review see ref. 21 ) and, in particular, isocyanide involving crystal engineering [22][23][24][25][26] , we focused our efforts on isocyanide species (CNR) featuring potential lp at the C atom. As a model XB acceptor for this study we addressed the isocyanide CNMes because of its broad usage, commercial availability, and excellent solubility in nonpolar solvents.…”

Dihalomethanes as Bent Bifunctional XB/XB‐Donating Building Blocks for Construction of Metal‐involving Halogen Bonded Hexagons

“…These interactions cooperatively connect molecules of metal complex and CH 2 X 2 providing their association to give 1D chains (Figure ). The detailed discussion of the parameters and nature of H 2 XC–X⋅⋅⋅X M –M interactions is given below, for discussion of X C ⋅⋅⋅M interactions and (π‐hole)⋅⋅⋅π contacts see the Supporting Information (section S4) …”

Novel tris(5‐aryl‐1H‐tetrazol‐1‐yl)methanes and 2‐dichloromethyl‐5‐aryl‐2H‐tetrazoles and noncovalent interactions in their crystal structure

“…According to the known data one may conclude that for the tetrazoles the π *‐orbital should be concentrated more on C atom rather than N atoms what makes the C atom to be more electrophilic and to act as π ‐hole . The relevant habit for carbon atom previously was showed for other heteroatomic π ‐systems like acyl compound, azines, isocyanides, nitriles, and carbon monoxide . However, to the best our knowledge the π ‐hole donor ability for tetrazoles was not reported earlier.…”