The scientific literature in chemistry and physics abounds with abbreviations of chemical compounds, physical methods and mathematical procedures. Unfortunately, many authors take it for granted that the reader knows the meaning of an abbreviation, something quite trivial for a specialist. For the less informed reader, these abbreviations thus present definite communication problems. The Gmelin Institute of Inorganic Chemistry of the Max Planck Society has collected more than 4000 abbreviations for methods and terms from chemistry, physics and mathematics and more than 4000 chemical compounds (mostly ligands in coordination chemistry and standard reagents for physical and analytical methods). GABCOM and GABMET provide an overview enabling readers and authors to check the definition of an abbreviation used by an author and to see whether this abbreviation is already being used for other purposes. GABCOM and GABMET are also in preparation in electronic form (data file and search software) for IBM-PC or compatible computers.

This volume 8 is the fourth in a series dealing with organomolybdenum compounds. An Empirical Formula Index and a Ligand Formula Index provide ready access to the compounds covered. Volume 5 describes mononuclear organomolybdenum compounds with isocyanide, 3 4 carbene, carbyne, alkynyl, alkene, alkyne, L, and L ligands with and without additional CO groups. Volume 6 starts the description of mononuclear organomolybdenum compounds with 5 one L Ligand, a Ligand bonded to molybdenum by five carbon atoms. The compounds contain either zero or one CO group bonded to the molybdenum atom. Volume 7 continues the 5 description of L-molybdenum compounds containing two CO groups, but no additional nl 5 ligands. This volume describes L-molybdenum compounds with two CO groups and additional 1 4 L to L ligands. Following the nomenclature used in this series of organomolybdenum com pounds, nl is an organic Ligand bonded by n C atoms to molybdenum, and mo is an electron 2 donor Ligand with m donor electrons. Thus 0 denotes a Ligand such as PR . 3 Many of the data, particular those in tables, are given in an abbreviated form without units; for explanations see p. X. Additional information, if necessary, is given before the individual table. Frankfurt am Main Manfred Winter November 1992 Wolfgang Petz X Remarks on Abbreviations and Dimensions Many compounds in this volume are presented in tables in which numerous abbreviations are used, the dimensions are omitted for the sake of conciseness. This necessitates the following clarifications.

"Organoiron Compounds" A, Ferrocene 10 systematicalty covers the literature through the end of 1986 and includes so me references published more recently. A formula index provides ready access to the compounds covered. This volume ends the description of mononuclear unbridged disubstituted ferrocenes, 1 2 FeC HRR . The description of the unbridged disubstituted ferrocenes was initiated with lO a 1 2 "Organoiron Compounds" A, Ferrocene 7 (starting with R and R containing C and Hand 1 containing halogen at least in R\ and continuing with compounds containing 0 at least in R to form alcohols and phenols, their esters, ethers, acetals, and aldehydes), and was foltowed 1 by "Organoiron Compounds" A, Ferrocene 8 (with at least R containing 0). "Organoiron 1 Compounds" A, Ferrocene 9 treated compounds in wh ich at least R contains N, S, Se, B, or Si. This volume now comprises the rest of the disubstituted ferrocenes containing P, As, or a 1 metal at least in R . Beyond that it includes the description of alt the mononuclear unbridged trisubstituted ferrocenes, FeClOH7R1R2R3. Series A so far comprises volumes A 1 to A 10 and has been surveyed in the preface to A 7 (1980). The data in tables are given in abbreviated form without dimensions; for dimensions, explanations, and further abbreviations used, see p. X (next page). Additional remarks are given in the headings of the tables where necessary.

The present volume contains all compounds in which at least one indium-carbon bonding interaction can be assumed. The compilation starts with the simplest compound of trivalent indium, In(CHh, and ends with studies about the interaction of indium with carbon monoxide 3 in an argon matrix. Literature coverage is intended to be complete to spring 1991 with various examples up to September 1991. The arrangement is closely related to that of the organogallium volume and documents the similarities between the two elements. Following the indium triorganyls and their adducts with Lewis bases in Section 1, the broad field of compounds of the general type R ln- n 3 n (n = 1, 2) is treated in sections 2 to 9; X represents a ligand bonded with a non-carbon atom to the indium atom. The arrangement of the various ligands follows the order group 17, 16, 15, etc. elements, with few compounds having direct indium-transition metal bonds. Ionic species, predominantly [R lnX -n]-compounds (n = 1 to 4), close the series of trivalent n 4 organoindium compounds and are collected in Section 11. Compounds of formally low valent indium (In", Ini, and Ino), with one R 1nlnR species having an In-In bond, form Section 12; 2 2 an extended chapter therein is dedicated to the young area of Cp*ln compounds in which i formalln is coordinated in an T] 5 manner.

The GmeLin series "Organometallic Compounds" comprises compounds containing at least one carbon-to-metal bond (except cyano compounds, which are considered inorganic). It includes all information in scientific journals, but patents, conference reports, and disserta- tions generally were not reviewed. The volumes published so far are listed on p. V/' Organometallic compounds are classified according to their nuclearity and the bonding mode of the organic ligands nL. Nuclearity means the number of atoms of the title metal in the formula unit disregarding any additional metals that may be present. The term nL designates a ligand bonded by n carbon atoms to one or different atoms of the title metal. As usual, a-bonded 1 L ligands are designated by R. Inorganic ligands (Le., ligands bonded exclusively by elements other than carbon) are generally designated by 0 or X. 0 means donor ligands such as pyridine or phosphanes; m-electron donors are specified by mO. X is reserved for negatively charged ligands or other one-electron donors such as halogens or SnR; bridging X ligands may donate one 3 2 2 2 (~-H), three (~-Cl, ~-OR), or five (~3-1) electrons. Terms such as lL_ 0, 20-X, or 20_ 0_ 0 may be used for multidentate ligands. Heterometals are often designated by M, and bridging elements, bridging groups, or nonmetallic cluster constituents by E. The symbols 1] and ~ follow the IUPAC nomenclature.

The present volume in the organogermanium series describes mononuclear compounds containing only germanium-carbon and germanium-hydrogen bonds (Chapter 1.3). Germanium hydrides with other additional non-carbon ligands, such as halogen or oxygen bonded groups, appear in later chapters according to the Gmelin principle of the last posi tion. Compounds with Ge-H and Ge-O bonds have already been described in Volume 5, Section 1.5.1.4, pp. 50/62. The present volume covers the literature to the end of 1992 and includes many references up to 1994. The nomenclature recommended by IUPAC has been generally adhered to. However, compound names were largely avoided, as most of the compounds are presented in tables and are only identified by their formulas. Many of the data in the tables appear in abbreviated form without units; general explanations are given on pp. X/XI. The volume contains an empirical formula index (p. 327) and a ligand formula index (p.341). The editor wishes to express his gratitude to the former author, Professor J. E. Drake, and to Professor J. Satge for his kind advice and fruitful collaboration. Thanks are due also to Dr. A. R. Pebler for editing the English text and to Mr. H.-G. Karrenberg for drawing the numerous formulas and molecular structures.

In der chemischen und physikalischen Fachliteratur werden hAufig AbkA1/4rzungen fA1/4r chemische Verbindungen sowie fA1/4r Arbeitsmethoden, mathematische Rechenverfahren u.a. verwendet. Leider ist es eine verbreitete Arbeitsweise, daA die Autoren als Spezialisten die fA1/4r sie triviale Kenntnis dieser AbkA1/4rzungen voraussetzen. FA1/4r den nicht spezialisierten Leser bereiten diese AbkA1/4rzungen daher gewisse VerstAndnisprobleme. Das Gmelin-Institut fA1/4r Anorganische Chemie der Max-Planck-Gesellschaft hat aus der Literatur des Zeitraums 1950-1990 eine Sammlung solcher AbkA1/4rzungen erarbeitet. Im vorliegenden Buch sind mehr als 4000 AbkA1/4rzungen fA1/4r Methoden und Begriffe aus Chemie, Physik und Mathematik und A1/4ber 4000 AbkA1/4rzungen fA1/4r chemische Verbindungen (insbesondere Komplexbildner und Standard-Substanzen physikalischer MeAmethoden) zusammengestellt. Mit GABCOM und GABMET kAnnen Leser und Autoren feststellen, was mit einer speziellen AbkA1/4rzung gemeint ist, bzw. ob die von ihnen gewAhlte AbkA1/4rzung nicht schon fA1/4r andere Verfahren oder Verbindungen benutzt wird. GABCOM und GABMET sind auch in elektronisch lesbarer Form (Daten und SuchoberflAche) fA1/4r IBM-PCs oder kompatible Rechner in Vorbereitung.