Electron‐Precise 1, 3‐Bishomocubanes – A Combined Experimental and Theoretical Study. Issue 33 (4th November 2015) - Barik, Subrat Kumar
Abstract: A combined experimental and quantum‐chemical study of a series of homometallic metallaheteroboranes [(Cp*M)2 E6 B2 H2 ] (M = Rh or RuH; E = S or Se; Cp* = η 5 ‐C5 Me5 ), which are analogues of 1, 3‐bishomocubane, is reported. The thermolysis of nido ‐[(Cp*Rh)2 B3 H7 ] (1 ) in the presence of S or Se powder in toluene yielded bishomocubane clusters [(Cp*Rh)2 (μ‐E)2 (μ3 ‐E)4 B2 H2 ], (3 : E = S; 4 : E = Se). In a similar fashion, the treatment of nido ‐[(Cp*RuH)2 B3 H7 ] (2 ) with S or Se powder in p ‐xylene yielded [(Cp*Ru)2 (μ‐E)2 (μ3 ‐E)4 B2 H2 ] (5 : E = S; 6 : E = Se) and [(Cp*Ru)2 (μ3 ‐Se)(μ4 ‐Se)B3 H5 ] (7 ). One of the noteworthy features of 3 –6 is the presence of an electron‐precise trichalcogenoborato ligand. All of the compounds have been characterized by mass spectrometry; IR spectroscopy; and 1 H, 11 B, and 13 C NMR spectroscopy. The structures of 3, 4, 6, and 7 were established unequivocally by X‐ray crystallographic analysis. Quantum‐chemical calculations by DFT methods for 3, 4, and 6 showed reasonable agreement with the experimentally observed structural parameters. The large HOMO–LUMO gaps are consistent with the high stabilities of these complexes. Abstract : Electron‐precise metallaheteroborane clusters [(Cp*M)2 E6 B2 H2 ] (M = Rh or Ru; E = S or Se; Cp* = η 5 ‐C5 Me5 ), which are analogous to 1, 3‐bishomocubane molecules, are isolated and characterized structurally.