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5424979 
Journal Article 
THE CRYSTAL AND MOLECULAR-STRUCTURE OF TRIS(TRANS-DICHLORO(MU-(1,2-BIS(3,5-DIMETHYLPYRAZOL-1-YL)ETHANE-N,N'))PALLADIUM(II)) - A MOLECULAR TRICORN 
Baker, AT; Crass, JK; Maniska, M; Craig, DC 
1995 
1 
Inorganica Chimica Acta
ISSN: 0020-1693
EISSN: 1873-3255 
230 
1-2 
225-229 
WOS:A1995QN71900036 
The ligand 1,2-bis(3,5-dimethylpyrazol-1-yl)ethane has been synthesized by the direct reaction of 1,2-dibromoethane and 3,5-dimethylpyrazole. The complex of this ligand with palladium(II) chloride has been prepared and the structure of its toluene solvate has been determined by X-ray crystallography. The compound crystallises in the triclinic space group P1, a = 11.088(5), b = 13.786(5), c = 21.169(9) Å, α = 86.96(3), β = 81.02(3), γ = 73.32(3)° with Z = 2. Final residuals after least-squares refinement: R = 0.030, Rw = 0.039. The compound has a trimeric structure which may be described as a ‘molecular tricorn’: the ligand bridges adjacent palladium centres, giving rise to a 21-membered trimetallic macrocycle. The overall structure closely approximates D3 symmetry with approximate two-fold axes passing through each palladium atom and the centre of the 1,2-ethanediyl moiety opposite. An interesting feature of the structure is the close approach of several hydrogen atoms from the 1,2-ethanediyl groups to each palladium centre; these interactions are thought to be close-packing rather than agostic bonds. 
PALLADIUM COMPLEXES; TRIMETALLIC MACROCYCLE; CRYSTAL STRUCTURES; POLYDENTATE LIGAND COMPLEXES; PYRAZOLYL COMPLEXES; TRIMERIC COMPLEXES