The preparation of the new compounds Ph,GaX, (X = C1, Br; n = 1,2) is reported. Both these and the corresponding aluminium chlorides are shown to be dimeric in benzene, and halogen-bridged structures are suggested. Confirmatory evidence is presented for the association of triphenylaluminium in solution as previously observed. The electrical conductances of triphenylgallium, diphenylgallium chloride, and phenylgallium dichloride have been determined over ranges of temperature; the results indicate that these compounds are mainly covalent.
The problems attending the estimation of gas-phase heats of formation and the calculation of reorganization energies are discussed and the results compared with those available on other Group I l l acceptors.A considerable body of data has been published on the heats of formation of co-ordination complexes of the halides 1 and aliphatic derivatives of the Group I11 eleinents.2 The corresponding aryl compounds however have been almost completely neglected and no thermochemical data whatsoever exist with regard to complex formation by these systems. It was the purpose of the present work to obtain such information and to compare the acceptor properties of the aryl compounds with those of the halides and alkyl systems. Such a comparison is particularly cogent in the light of recent work3 on the x bonding energies of these systems, a factor which is usually considered to be dominant in determining the strength of an electron acceptor.
RESULTS AND DISCUSSIOXGeneral Pro$erties.-All the four triphenyl compounds and diphenylgallium chloride reacted with liquid pyridine at room temperature yielding, finally, stable solid 1 : 1 complexes. Two of these complexes, Ph3B,py and Ph,Al,py, have been reported previously 4,5 but since the recorded melting points were about 30" lower than ours it seems that they were to some extent impure. Triphenylindium initially retained more than 1 mole of yyridine per mole of Ph31n (although the excess was evolved on heating) thus indicating that the 1 : 1 complex is the most stable. All four compounds are essentially monomeric in benzene solution. The lower degree of association of Ph,In,py in more dilute solution (0.91 wt. yo) suggests that some dissociation of the complex is occurring, a not uncommon effect in Group I11 complexes.Although all four compounds melted without apparent decomposition, vacuum sublimation of Ph,Ga,py at 140" led to a solid which melted 4" lower than the original. The i.r. spectra of the. two substances appeared to be identical and hence it is assumed that only
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.