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Cationic Triple‐Decker Complexes with a Bridging 4‐Borataborepine Ligand: Synthesis, Structure, and Bonding
Author(s) -
Mutseneck Elena V.,
Wadepohl Hubert,
Kudinov Alexander R.,
Siebert Walter
Publication year - 2008
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/ejic.200800008
Subject(s) - chemistry , cationic polymerization , ruthenium , stereochemistry , ligand (biochemistry) , electrophile , stacking , medicinal chemistry , triple bond , crystallography , catalysis , double bond , receptor , organic chemistry , polymer chemistry , biochemistry
Cationic 30 VE triple‐decker complexes [Cp*Ru(μ‐η 7 :η 7 ‐C 5 B 2 Me 6 H)ML] + [ML = Co(C 4 Me 4 ) ( 3a ), RuCp* ( 4a ), Rh(cod) ( 7a ), and Ir(cod) ( 8a )] with a bridging hexamethyl‐4‐borataborepine ligand were obtained by electrophilic stacking of the sandwich compound Cp*Ru(η 7 ‐C 5 B 2 Me 6 H) ( 2a ) with [ML] + complex fragments. The reaction of the phenyl‐substituted derivative Cp*Ru(η 7 ‐7‐PhC 5 B 2 Me 5 H) ( 2b ) with [(C 4 Me 4 )Co(MeCN) 3 ] + selectively affords the triple‐decker complex [Cp*Ru(μ‐η 7 :η 7 ‐7‐PhC 5 B 2 Me 5 H)Co(C 4 Me 4 )] + ( 3b ), whereas a similar reaction with [Cp*RuCl] 4 /TlBF 4 produces a 1:3 mixture of cations, the triple‐decker [Cp*Ru(μ‐η 7 :η 7 ‐7‐PhC 5 B 2 Me 5 H)RuCp*] + ( 4b ) and the arene‐coordinated [Cp*Ru(μ‐η 6 :η 7 ‐7‐PhC 5 B 2 Me 5 H)RuCp*] + ( 5 ). Stacking of Cp*Ru(η 7 ‐7‐PhCH 2 C 5 B 2 Me 5 H) ( 2c ) with [CpRu(MeCN) 3 ] + selectively gives the triple‐decker complex [Cp*Ru(μ‐η 7 :η 7 ‐7‐PhCH 2 C 5 B 2 Me 5 H)RuCp] + ( 6c ). The dinuclear cations 3 – 8 were isolated as deep‐colored air‐stable salts with [BF 4 ] – or [PF 6 ] – anions in moderate to high yields. Structures of 3b PF 6 , 4a BF 4 , 7a BF 4 , and 8a BF 4 were confirmed by X‐ray diffraction studies. Energy decomposition analysis of complexes CpRu(ring) and [CpRu(ring)RuCp] + (ring = Cp, C 5 BH 6 , C 5 B 2 H 7 ) revealed that the insertion of BH units makes the bonding between [ring] – and [RuCp] + more covalent. According to Mulliken population analysis, weakening of π‐donation and strengthening of δ‐back donation occur in the same order. The electrostatic character of the bond and the contribution of σ‐donation to the covalent bonding are higher in the case of bifacially bonded rings. The boron‐containing triple‐decker complexes are considerably more stable than the cyclopentadienyl analog. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)