Mechanisms of Inorganic and Organometallic Reactions provides an ongoing critical review of the primary literature concerned with mechanisms of inorganic and organometallic reactions. The main focus is on reactions in solution, although solid-state and gas-phase studies are included where they provide relevant mechanistic insight. Each volume covers an eighteen-month literature period, and this, the eighth volume in the series, includes papers published during January 1990 through June 1991. Where appropriate, references to earlier reports and to specific sections in previous volumes are given. Coverage spans the whole area as comprehensively as possible in each volume, and while it is impossible to be absolutely exhaustive, every effort is made to include all of the important published work that is relevant to the elucidation of reaction mechanisms. Numerical data are reported in the units used by the original authors, and they are converted to common units only when comparisons are being made. The successful format of earlier volumes is retained to facilitate tracing progress over several years in a particular topic, and the series now permits this to be done for a twelve-year period. The introduction three volumes ago of computerized techniques to improve cross-referencing in the Index brought positive reader comments, and their use is being continued.