TY - JOUR
T1 - Conformational polymorphism and fluxional behaviour of M(PR3)2 units in closo-twelve-atom metallaheteroboranes with MX2B9 (X = C or As) and MZB10 cages (Z = S, Se or Te)
AU - O'Connell, Donnacha
AU - Patterson, Jennifer C.
AU - Spalding, Trevor R.
AU - Ferguson, George
AU - Gallagher, John F.
AU - Li, Yiwei
AU - Kennedy, John D.
AU - Macías, Ramón
AU - Thornton-Pett, Mark
AU - Holub, Josef
PY - 1996/8/7
Y1 - 1996/8/7
N2 - The compounds [3,3-(PEt3)2-closo-3,1,2-PtAs2B 9H9] 1 and [2,2-(PMe2Ph)2-closo-2,1-PtSB10H10] 2 were synthesised and characterised by NMR spectroscopy and X-ray crystallography. Crystals of 1 exhibit conformational polymorphism with five conformers of the Pt(PEt3)2 unit above the As2B3 face; those of 2 contain single conformers. The free energy of the barrier to rotation of the Pt(PMe2Ph)2 unit above the SB10 cage ligand in 2 has been determined in chloroform solution and is compared with data from other platinum and palladium metallaheteroboranes containing C2B9H11, As2B9H9, SeB10H10 and TeB10H10 ligands. A mechanism for the rotation of M(PR3)2 units above heteroborane ligand faces is suggested. It involves shifting the M(PR3)2 unit via ηn-bonded species (n < 5) with a concomitant twisting of the M(PR3)2 unit about an axis passing approximately through the metal atom and the antipodal B atom.
AB - The compounds [3,3-(PEt3)2-closo-3,1,2-PtAs2B 9H9] 1 and [2,2-(PMe2Ph)2-closo-2,1-PtSB10H10] 2 were synthesised and characterised by NMR spectroscopy and X-ray crystallography. Crystals of 1 exhibit conformational polymorphism with five conformers of the Pt(PEt3)2 unit above the As2B3 face; those of 2 contain single conformers. The free energy of the barrier to rotation of the Pt(PMe2Ph)2 unit above the SB10 cage ligand in 2 has been determined in chloroform solution and is compared with data from other platinum and palladium metallaheteroboranes containing C2B9H11, As2B9H9, SeB10H10 and TeB10H10 ligands. A mechanism for the rotation of M(PR3)2 units above heteroborane ligand faces is suggested. It involves shifting the M(PR3)2 unit via ηn-bonded species (n < 5) with a concomitant twisting of the M(PR3)2 unit about an axis passing approximately through the metal atom and the antipodal B atom.
UR - https://www.scopus.com/pages/publications/33748513443
U2 - 10.1039/DT9960003323
DO - 10.1039/DT9960003323
M3 - Article
AN - SCOPUS:33748513443
SN - 1470-479X
SP - 3323
EP - 3333
JO - Journal of the Chemical Society. Dalton Transactions
JF - Journal of the Chemical Society. Dalton Transactions
IS - 15
ER -