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Protonation of the complexes [M(q2-CH,=CHPh) (L-L)] [M = Pt, L-L = (C,H,,),P(CH,),P(C,H,,),, n = 2 or 3 ( l a or lc), But,P(CH,),PBut2, n = 2 or 3 ( l b or I d ) , and Bu',PCH,C,H,CH,PBu', (le); M = Pd, L-L = But,P(CH,),PBut,, n = 2 or 3 ( I f or l g ) and Bu',PCH,C6H,CH,PBut, (1 h)] with HBF, in diethyl ether affords a series of complexes, [M(q3-MeCHPh)(L-L)] [BF,] (2a-2h), which contain an q3-methylbenzyl ligand. The complexes 2a-2h were characterized by 'H, 13C and 31P N M R spectroscopy and all except 2a and 2f were found to undergo intramolecular rearrangement in solution at or below room temperature. A mechanism is proposed, on the basis of variable-temperature N M R studies, that involves an q3 e CJ conversion coupled with single-bond rotation and P-elimination/hydride migration processes.For 2a-2e, the influence of the chelating diphosphine o n the nature of t h e q3-benzyl interaction was investigated by 31P-{1H} NMR spectroscopy and it was found that the largest diphosphines induce the most asymmetric q3 interaction. Similarly, it was found that the activation barriers to intramolecular rearrangement are lowest for the complexes with the largest diphosphine ligands.

The deprotonation of (p-H)Fe3(CO)g(p-CO) (p3-HBH) with n-butyllithium yields the dianionic complex [Li]2[Fe3(C0)9(p3-HBCO)], which has been spectroscopically characterized. In contrast to the facile reprotonation of closely related ferraboranes, protonation of [LiIz[Fe3(CO)g(p3-HBCO)] leads to decomposition. On the other hand, reaction of this dianionic complex with 2 equiv of FeCl3 gives a good yield of [Li] [ F~~( C O )~( C~-C O ) (~~-H B C~) . Metathesis with [AsPhJ-[Cl] yields [AsPh] [ F~~( C O ) S (~-C O ) (~~-H B C~) ], which has been crystallographically characterized (triclinic, Pi, a = 9.534(3) A, b = 13.305(4) A, c = 15.225(4) A, a = 104.39(2)', /? = 103.56(2)', y = 99.23(2)', V = 1768.7(8) A3, 2 = 2). Comparison with the analogous osmium clusters, as well as isoelectronic organometallic clusters, reveals relationships among their structures, properties, and energetics.

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Reaction of the platinum(o) styrene complexes [Pt(q2-CH2=CHC,H4X){Bu',P(CH,),PBut2}] I a-If (X = Br-3, Br-4, Me-4, F-4, F -3 or Me0-4) with HBF, in diethyl ether afforded the q3-methylbenzyl complexes [Pt(q3-MeCHC,H4X){But2P(CH,),PBut2}] [BF,] 2a-2f. The effect of phenyl substitution on the asymmetry of the q3-methylbenzyl interaction was measured by 31P-{1H} NMR spectroscopy and it was found that, in general, the more electron releasing the substituent, X, the more asymmetric is the bonding. Complexes 2a-2f lose styrene reversibly to form the hydride-bridged dinuclear platinum complex [Pt2(p-H)2{Bu'2P(CH2)3PBut2}2] [ BF,],. Displacement of styrenes from 2a-2f by ethene and bicyclo[2.2.1] hept-2-ene affords known complexes stabilized by a three-centre, two-electron (agostic) bond.