Pyrazolylborate Nickel(II) Complexes as Catalysts for the Formation of Polyketones from Ethene and Carbon Monoxide − Partial Hydrolysis of the Bis(pyrazolyl)borate Yields a Pyrazolyl(hydroxo)borate Ligand

• Published in: European journal of inorganic chemistry Vol. 2002; no. 1; pp. 205 - 209
• Main Authors: Kläui, Wolfgang, Turkowski, Barbara, Rheinwald, Gerd, Lang, Heinrich
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01-01-2002; WILEY‐VCH Verlag GmbH
• Subjects: Copolymerization; Homogeneous catalysis; N ligands; Nickel; Polyketones; Solvolysis
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/1099-0682(20021)2002:1<205::AID-EJIC205>3.0.CO;2-S

The new nickel(II) complex [Ni{BBN(pz)2}(o‐tol)(PPh3)] (1) of the bis(pyrazolyl)borate ligand [BBN(pz)2]− (BBN = 1,5 borabicyclo[3.3.1]nonane) has been prepared by reaction of [NiBr(o‐tol)(PPh3)2] with K[BBN(pz)2]. In the presence of moisture this reaction yields the nickel(II) complex [Ni{BBN(pz)(OH)}(o‐tol)(PPh3)] (2). The hydroxoborate ligand [BBN(pz)(OH)]− acts as an N,O‐chelate ligand in 2. Compound 1 and the analogous nickel complex [Ni{HB(3‐Phpz)3}(o‐tol)(PPh3] show very similar activity in the catalytic copolymerization of carbon monoxide and ethene. This suggests that the borane hydrogen and the noncoordinated pyrazolyl ring in the latter are not essential for the catalysis. Compound 2 is inactive. Both 1 and 2 were characterised by X‐ray crystallography.