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A New Family of Organometallic Rhodium Complexes with [Rh(P i Pr 2 Ph) 2 ] and [Rh(P i PrPh 2 ) 2 ] as Molecular Units
Author(s) -
Werner Helmut,
Kukla Frank,
Steinert Paul
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200206)2002:6<1377::aid-ejic1377>3.0.co;2-d
Subject(s) - chemistry , rhodium , alkyne , denticity , substituent , medicinal chemistry , octahedron , stereochemistry , chelation , crystal structure , catalysis , crystallography , organic chemistry
The π‐allyl complexes [Rh(η 3 ‐C 3 H 5 )(PR 3 ) 2 ] [PR 3 = P i Pr 2 Ph ( 4 ), P i PrPh 2 ( 5 )], prepared from [RhCl(C 8 H 14 ) 2 ] 2 , PR 3 and the Grignard reagent C 3 H 5 MgBr, react with carboxylic acids and p ‐toluenesulfonic acid to give the chelate compounds [Rh(κ 2 ‐O 2 CR′)(PR 3 ) 2 ] ( 8 − 10 ) and [Rh{κ 2 ‐O 2 S(O)‐ p ‐Tol}(PR 3 ) 2 ] ( 11 , 12 ), respectively. While the reactions of 8 , 10 and 12 with CO afford the square‐planar rhodium(I) complexes 13 − 15 with monodentate carboxylato and tosylato ligands, treatment of 8 − 10 and 11 , 12 with H 2 leads to the formation of the octahedral dihydridorhodium(III) derivatives [RhH 2 (κ 2 ‐O 2 CR′)(PR 3 ) 2 ] ( 16 − 18 ) and [RhH 2 {κ 2 ‐O 2 S(O)‐ p ‐Tol}(PR 3 ) 2 ] ( 19 , 20 ). Similarly to CO, internal alkynes RC≡CCO 2 Me (R = CO 2 Me, Me) react with 8 and 9 by partial opening of the chelate bond to yield the π‐alkyne complexes 21 − 23 , of which 23 with R = Me is quite labile and smoothly regenerates the starting material. In contrast, the reactions of 8 and 9 with terminal alkynes HC≡CR (R = Ph, CO 2 Me) afford six‐coordinate alkynyl(vinyl)rhodium(III) compounds 24 − 26 with a different stereochemistry at the C=C double bond depending on the substituent R. From 8 and HC≡CCH(Cl)Me the octahedral allenyl complex [RhCl(CH=C=CHMe)(κ 2 ‐O 2 CR′)(P i PrPh 2 ) 2 ] ( 27 ) is obtained, the molecular structure of which has been determined by X‐ray crystallography. The reaction of [Rh(κ 1 ‐O 2 CR){η 2 ‐C 2 (CO 2 Me) 2 }(P i PrPh 2 ) 2 ] ( 21 , 22 ) with HC≡CPh also leads to the six‐coordinate alkynyl(vinyl)rhodium(III) compounds 28 , 29 , which upon treatment with Me 3 SiCl and thermolysis are stepwise converted into the four‐coordinate π‐enyne complex trans ‐[RhCl{η 2 ‐Ph C ≡ C C(CO 2 Me)=CHCO 2 Me}(P i PrPh 2 ) 2 ] ( 31 ). The reaction of 31 with CO generates the uncoordinated substituted enyne. The rhodium(I) vinylidene complexes trans ‐[Rh(C≡CR′)(=C=CHR)(P i PrPh 2 ) 2 ] ( 36 − 38 ) were prepared in two steps from the tosylato complex 12 and terminal alkynes; they react with CO via migratory insertion to give the square‐planar enynyl compounds trans ‐[Rh{η 1 ‐C(C≡CR)=CHR′}(CO)(P i PrPh 2 ) 2 ] ( 39 − 41 ). (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)