Syntheses, Structures, and Bonding of Cp2M(ER)2 Compounds (Cp = C5H5; M = Ti, Zr; E = Ga, In; R = C6H3-2,6-(2,4,6-i-Pr3C6H2)2)

Sodium or magnesium metal reduction of Cp 2 MCl 2 (Cp = C 5 H 5; M = Zr, Ti) with RECl 2 (E = Ga, In; R = C 6 H 3 -2,6-(2,4,6- i -Pr 3 C 6 H 2 ) 2 ) affords heteronuclear organometallic compounds, Cp 2 M(ER) 2, with new types of group 4−group 13 M−E bonds (Zr−Ga ( 1 ), Ti−Ga ( 2 ), Zr−In ( 3 ), Ti−In ( 4 )). These compounds have been characterized by elemental analyses, 1 H and 13 C NMR spectroscopy, and single-crystal X-ray diffraction analyses. The structures of 1 − 4 have V-shaped E−M−E trimetallic linkages with quite short M−E bonds (Zr−Ga, 2.6350(8) Å; Ti−Ga, 2.4921(7) Å; Zr−In, 2.7916(5) Å; Ti−In, 2.6685(8) Å). The transition metal (M = Zr, Ti) centers adopt a pseudo-tetrahedral coordination geometry, while the main group metal (E = Ga, In) atoms reside in a two-coordinate, almost linear environment. Density functional theory (DFT) computations on the model compounds Cp 2 M(EPh) 2 ( 1Ph − 4Ph ) suggest significant π-back-bonding from the group 4 metals (Zr, Ti) to the group 13 metals (Ga, In) in these compounds.