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Closing the Gap between MC 3 and MC 5 Metallacumulenes: The Chemistry of the First Structurally Characterized Transition‐Metal Complex with MCCCCR 2 as the Molecular Unit
Author(s) -
Ilg Kerstin,
Werner Helmut
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020617)8:12<2812::aid-chem2812>3.0.co;2-c
Subject(s) - iridium , chemistry , electrophile , stereochemistry , medicinal chemistry , yield (engineering) , octahedron , metathesis , crystallography , crystal structure , organic chemistry , catalysis , physics , polymer , polymerization , thermodynamics
The reactions of the dihydrido compound [IrH 2 Cl(P i Pr 3 ) 2 ] ( 3 ) with HCCC(O)CHPh 2 and HCCC(OAc)CPh 2 lead to the formation of alkynyl(hydrido)iridium( III ) and vinylideneiridium( I ) complexes 4 – 7 which, however, are not suitable precursors for the target molecule trans ‐[IrCl(CCCCPh 2 )(P i Pr 3 ) 2 ] ( 8 ). Compound 8 has been prepared in 77 % yield from 3 and the vinyl triflate HCCC(OTf)CPh 2 in the presence of NEt 3 . Treatment of 8 with CF 3 CO 2 H affords the vinylvinylidene complex trans ‐[IrCl{CCHC(O 2 CCF 3 )CPh 2 }(P i Pr 3 ) 2 ] ( 10 ) by addition of the electrophile to the C β C γ bond of the MC 4 chain. In contrast, the reaction of 8 with HCl yields the five‐coordinate butadienyliridium( III ) compound [IrCl 2 { η 1 ‐( Z )‐CHCHC(Cl)CPh 2 }(P i Pr 3 ) 2 ] ( 11 ). Salt metathesis of 8 with KI, KOH, and NaN 3 leads to the formation of the substitution products trans ‐[IrX(CCCCPh 2 )(P i Pr 3 ) 2 ] ( 12 – 14 ) of which the hydroxo derivative 13 reacts with phenol to give trans ‐[Ir(OPh)(CCCCPh 2 )(P i Pr 3 ) 2 ] ( 15 ). From 13 and methanol, the octahedral dihydridoiridium( III ) complex [IrH 2 (CHCCCPh 2 )(CO)(P i Pr 3 ) 2 ] ( 16 ) is formed by fragmentation of the alcohol. In the presence of CO, both the methyl compound trans ‐[Ir(CH 3 )(CCCCPh 2 )(P i Pr 3 ) 2 ] ( 17 ) (generated from 8 and CH 3 Li) and the azido complex 14 (X=N 3 ) undergo migratory insertion reactions to yield the four‐coordinate iridium( I ) carbonyls trans ‐[Ir(C(CCCH 3 )CPh 2 )(CO)(P i Pr 3 ) 2 ] ( 18 ) and trans ‐[Ir(CCC(N 3 )CPh 2 )(CO)(P i Pr 3 ) 2 ] ( 19 ), respectively. Compound 19 rearranges slowly to the thermodynamically more stable isomer trans ‐[Ir(C(N 3 )CCCPh 2 )(CO)(P i Pr 3 ) 2 ] ( 20 ). The molecular structures of 8 and 18 have been determined crystallographically.