Schneider, Jorg J.; Denninger, Uwe; Hagen, Jorg; Kruger, Carl; Blaser, Dieter; Boese, Roland:

Reactivity of the heavier Group-13 monochlorides [{CH(SiMe3)2}2AlCl], InCl, TlCl, and of the elements Ga and Hg towards the unsupported Ni-Ni bond of [{(h5-Cp)Ni(PEt3)}2]. A straightforward synthetic approach to the synthesis of mixed main-Group/transition-metal clusters containing unsupported metal-metal bonds.

In: Chemische Berichte/Recueil, Jg. 130 (1997) ; Nr. 10, S. 1433-1440
Zeitschriftenaufsatz / Fach: Chemie
The dinuclear compd. [{(h5-Cp)Ni(PEt3)}2] contg. an unbridged Ni-Ni bond reacts with the heavier Group-13 monochlorides [{CH(SiMe3)2}2AlCl], InCl, and TlCl by scission of the metal-metal bond. In the case of InCl and TlCl the Cl-bridged dimers [{(h5-Cp)Ni(PEt3)2ECl}2] (I; E = In, Tl) were formed. Compd. I (E = Tl) is unstable and decomps. via disproportionation and formation of halogen-free [{(h5-Cp)Ni(PEt3)}3E] (II, E = Tl). Compd. I (E = In) can be dehalogenated with activated Mg to yield halogen-free II (E = In). The Ga analog II (E = Ga) is accessible by a conproportionation of [{(h5-Cp)Ni(PEt3)}2] with Ga metal in refluxing THF. In contrast to InCl and TlCl, the Al(III) monochloride [{CH(SiMe3)2}2AlCl] reacts with [{(h5-Cp)Ni(PEt3)}2] by a ligand redistribution reaction and formation of the salt [(h5-Cp)Ni(PEt3)2]+[{CH(SiMe3)2}2AlCl2]- (III). Elemental Hg or Mg amalgam show the same activity as elemental Ga towards [{(h5-Cp)Ni(PEt3)}2] and insert into the Ni-Ni bond by forming the linear Hg-bridged [{(h5-Cp)Ni(PEt3)}2Hg] (IV). The mol. structures of I (E = In), II (E = In), III and IV were detd. by x-ray crystallog. The In atom in II (E = In) has a distorted trigonal-planar configuration with the central In atom being surrounded by 3 [(h5-Cp)Ni(PEt3)] fragments. Compd. II (E = In) represents the first Ni-In cluster contg. exclusively unsupported In-Ni bonds, as well as the first carbonyl-free Ni-In cluster. On the basis of spectroscopic data the same structure is assigned to the Ga and Tl analogs of II (E = In). The Ni-Hg-Ni arrangement in IV (E = Hg) is exactly linear, as detd. by x-ray crystallog.