~ Pergamon PII : S0277-5387(97)00499-3 PolyhedronVol. 17, No. 7, pp, 1121 1131, 1998 ,~" 1998 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0277 5387/98 $19.00+0.00 Cycloalkanes as ligand backbones part 5 [1] coordination chemistry of trans-2-pyrazol-1- ylcyclohexan-l-ol and derivatives: synthesis, spectroscopic features and solid state structures of first and second row transition metal complexes? M. Barz, E. Herdtweck and W. R. Thiel* Anorganisch-chemisches Institut der Technischen Universit~it M~nchen, Lichtenbergstr. 4, D-85747 Garching, Germany (Received 25 September 1997; accepted 22 October 1997) Abstract--The synthesis and spectroscopic and structure chemical properties of complexes with the ligands trans-2-pyrazol-l-ylcyclohexan-l-ol (1), cis-(l-amino)(2-pyrazol-l-yl)cyclohexane (2) and 2-pyrazol-l-ylcy- clohexanonoxime (4) coordinated to a variety of first and second row transition metals are described. These new systems bear cycloalkane backbones, which give rise to rigid ligand arrangements at the metal centre. X- ray crystallographic investigations of the copper(II) complexes CUC12(1)2" (H20)2 (Se) and [Cu(1)2](CuC14) (5t") proved the coordination of two different enantiomers of ligand 1 to one copper centre. Owing to their d 9 configuration, both octahedrally coordinated metal centres show typical Jahn-Teller distortions with either loosely bound chloro ligands or bridging CuC1] anions occupying the apical positions. The copper(If) complex [CuCl2(2)]2" (6) forms dimers in the solid state, wherein the trigonal bipyramidally coordinated Cu centres are linked by bridging chloro ligands. © 1998 Elsevier Science Ltd. All rights reserved Keywords: chiral ligands ; amino alcohols ; transition metal complexes ; crystal structure. During the last years, complexes of 1,2-amino alco- hols have been applied for MOCVD [2] and, in the case of chiral systems, as catalysts for enantioselective transformations [3]. While the coordination chemistry of aliphatic 1,2-amino alcohols is well established [4], relatively few transition and main group element com- plexes bearing chelating 1,3-amino alcohols [5] or 1,2- amino alcohols with aromatic N-donor sites [6], have been structurally investigated. We are interested in 1,3-amino alcohols with aromatic pyrazolyl N-donor fragments, where both donor sites are attached to a rigid cyclolkane backbone. These ligands can be obtained easily and in high yields by nucleophilic attack ofa pyrazole derivative to an epoxicycloalkane. * Author to whom correspondence should be addressed. t Dedicated to Prof. Dr. Drs. h. c. W. A. Herrmann on the occassion of his 50th birthday. The reaction leads, under opening of the oxirane ring, to the corresponding 1,2-trans configurated cycloal- kanols, with both substituents in equatorial orien- tation (Scheme 1). Since we are interested in these compounds as chiral ligands for enantioselective catalysis, we worked out a route for kinetic resolution of the resulting race- mates. In the presence of lipase B from candida ant- arctica, the esterification of the (R,R)-enantiomers is performed with enantiomeric excesses of more than 95% [7]. The resulting esters can be separated from the alcohols by crystallization or preparative MPLC. Following this procedure, both enantiomers of the chelate ligands are available in amounts of several grams in high stereochemical purity. These new chiral compounds are also versatile starting materials for the synthesis of enantiomerically pure multidentate ligand systems. In this paper, we report the coordination chemistry of trans-2-pyrazol-l-ylcyclohexan-l-ol (1t 1121