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[Cp 2 V] Migration along an Octatetrayne Chain: From the Monometallic Complex [Cp 2 V(3‐4η‐ t BuC≡CC 2 −C≡CC≡C t Bu)] to the Dimetallic Complex [(Cp 2 V) 2 (1‐2η:7‐8η‐ t BuC 2 −C≡CC≡CC 2 t Bu)]
Author(s) -
Choukroun Robert,
Donnadieu Bruno,
Lorber Christian,
Pellny PaulMichael,
Baumann Wolfgang,
Rosenthal Uwe
Publication year - 2000
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(20001215)6:24<4505::aid-chem4505>3.0.co;2-y
Subject(s) - triple bond , chemistry , ligand (biochemistry) , single bond , stereochemistry , crystallography , double bond , group (periodic table) , biochemistry , receptor , organic chemistry , polymer chemistry
The oxidative addition of one equivalent of [Cp 2 V] ( 4 ) to the tetrayne ligand t BuC≡CC≡CC≡CC≡C t Bu ( 5 ) gives the monometallic complex [Cp 2 V(3‐4η‐ t BuC≡CC 2 −C≡CC≡C t Bu)] ( 7 ). Compound 7 reacts further with a second equivalent of [Cp 2 V] to give the dimetallic complex [(Cp 2 V) 2 (1‐2η:7‐8η‐ t BuC 2 −C≡CC≡CC 2 t Bu)] ( 8 ), which involves a shift of the first coordinated [Cp 2 V] unit from the internal C3–C4 to the external C1–C2 positions on the alkynyl ligand. Compound 8 is also directly obtained by the addition of two equivalents of [Cp 2 V] to 5 . Reversibly, reaction of 8 with 5 leads to 7 . This exchange reaction between 7 and 8 by adding successively 5 and 4 has been monitored by EPR spectroscopy. By contrast, the oxidative addition of one or two equivalents of [Cp 2 V] to the tetrayne ligand PhC≡CC≡CC≡CC≡CPh ( 6 ) gives the homodimetallic complex [(Cp 2 V) 2 (1‐2η:7‐8η‐PhC 2 −C≡CC≡CC 2 Ph)] ( 9 ). Both monometallic and dimetallic complexes 7, 8 , and 9 have been characterized by X‐ray diffraction. Magnetic moment measurements for 8 and 9 from 300 to 4 K indicated a weak antiferromagnetic J exchange coupling of −12.5 and −4.1 cm −1 , respectively.