51. Synthesis, detailed geometric analysis and bond-valence method evaluation of the strength of π-arene bonding of two isotypic cationic prehnitene tin(II) complexes: [{1,2,3,4-(CH 3 ) 4 C 6 H 2 } 2 Sn 2 Cl 2 ][ M Cl 4 ] 2 ( M = Al and Ga).
- Author
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Merkelbach J and Frank W
- Abstract
From solutions of prehnitene and the ternary halides (SnCl)[ M Cl
4 ] ( M = Al, Ga) in chloro-benzene, the new cationic SnII -π-arene complexes catena -poly[[chlorido-aluminate(III)]-tri-μ-chlorido-4':1κ2 Cl ,1:2κ4 Cl -[(η6 -1,2,3,4-tetra-meth-yl-benzene)-tin(II)]-di-μ-chlorido-2:3κ4 Cl -[(η6 -1,2,3,4-tetra-methyl-benzene)-tin(II)]-di-μ-chlorido-3:4κ4 Cl -[chlorido-aluminate(III)]-μ-chlorido-4:1'κ2 Cl ], [Al2 Sn2 Cl10 (C10 H14 )2 ]n , ( 1 ) and catena -poly[[chlorido-gallate(III)]-tri-μ-chlor-ido-4':1κ2 Cl ,1:2κ4 Cl -[(η6 -1,2,3,4-tetra-methyl-benzene)-tin(II)]-di-μ-chlorido-2:3κ4 Cl -[(η6 -1,2,3,4-tetra-methyl-benzene)-tin(II)]-di-μ-chlorido-3:4κ4 Cl -[chlor-ido-gallate(III)]-μ-chlorido-4:1'κ2 Cl ], [Ga2 Sn2 Cl10 (C10 H14 )2 ]n , ( 2 ), were isolated. In these first main-group metal-prehnitene complexes, the distorted η6 arene π-bonding to the tin atoms of the Sn2 Cl2 2+ moieties in the centre of [{1,2,3,4-(CH3 )4 C6 H2 }2 Sn2 Cl2 ][ M Cl4 ]2 repeating units (site symmetry ) is characterized by: (i) a significant ring slippage of ca 0.4 Å indicated by the dispersion of Sn-C distances [ 1 : 2.881 (2)-3.216 (2) Å; 2 : 2.891 (3)-3.214 (3) Å]; (ii) the non-methyl-substituted arene C atoms positioned closest to the SnII central atom; (iii) a pronounced tilt of the plane of the arene ligand against the plane of the central (Sn2 Cl2 )2+ four-membered ring species [ 1 : 15.59 (11)°, 2 : 15.69 (9)°]; (iv) metal-arene bonding of medium strength as illustrated by application of the bond-valence method in an indirect manner, defining the π-arene bonding inter-action of the SnII central atoms as s (SnII -arene) = 2 - Σ s (SnII -Cl), that gives s (SnII -arene) = 0.37 and 0.38 valence units for the aluminate and the gallate, respectively, indicating that comparatively strong main-group metal-arene bonding is present and in line with the expectation that [AlCl4 ]- is the slightly weaker coordinating anion as compared to [GaCl4 ]- .- Published
- 2019
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