Bjerrum, Jannik

In the preceding section, we have described two methods that are frequently used to determine the composition of complexes in solution. We will now turn our attention to a consideration of the simultaneous equilibria that are involved in complex formation. The widely used approach described here is known as Bjerrum s method, and it was described by Jannik Bjerrum many years ago. 

In 1932, Jannik Bjerrums) started work on ammonia complexes of copper(l) and Cu(II). Some of the results were obtained with more direct techniques, such as measurement of the ammonia vapour pressure over the solution, or solubility of weakly soluble salts in various supernatant solutions. However, most of the work involved determination of the free concentration of ammonia [NH3 ] via measurements with a glass electrode of... 

Jannik Bjerrum Theory of the reversible step reactions... 

Fred maintained an international perspective, spending sabbatical leaves with Jannik Bjerrum (1954-1955) and Vincenzo Caglioti (1961-1962). He regarded Italy as a second home and was elected to the Accademia Nazionale dei Lincei (1987), the world s oldest scientific society. He coauthored Coordination Chemistry (1964, 1986) with former student Ronald C. Johnson. Fred cofounded the Inorganic Gordon Research Conference, which continues today. 

In 1948, Jannik Bjerrum became the director of KLA and professor at the University of Copenhagen. His dissertation, from 1937, was entitled Metal Ammine Formation in Aqueous Solutions. Bjerrum was a prominent complex chemist, but he never became comfortable with quantum mechanics. He did not make a secret of this, however. 

Since a good deal of the pioneering work on equilibria of complex ions was carried out in Sweden and Denmark, Joseph thought it would be a good idea to visit and talk with some of the people there who were known to us only as names. I was pleased when Joseph asked me to accompany him. We had an enjoyable and fruitful trip in June of 1952. We were fortunate to meet both Bjerrums (Nils and Jannik), Kai Jensen (who had done early studies of tertiary phosphine, arsine... 

For discussions of Jannik Bjerrum and his work, see Chapters 8 and 9 in this book. 

Jannik Bjerrum will be commemorated also in an "interview," which is planned to appear in Coordination Chemistry Reviews. Jorgensen and I shall therefore view Jannik and his work with our own eyes and, hopefully, with the eyes of many others who either knew him personally or had encountered his work. 

Jannik Bjerrum s Early Work The Copper(II)- and Copper(I)-Anunine Systems... 

As one often sees in the history of chemistry, observations of scientists in their early years influence their work of much later years. There is no doubt that JB s early interest in the colors of complexes and, in particular, in the relationship between the colors and the structures became the basis for his inspiration of his entire laborato almost 25 years later (see here Christian Klixbiill Jorgensen s contribution about Jannik Bjerrum at this symposium). 

One of Jannik Bjerrum s last papers (20) was coauthored by his youngest son, Morten and concern JB s father s first system (70), the extremely weakly complex chromium(III)-chloride system. 

Jannik Bjerrum s Later Life—Turning Toward Chemical Physics Personal Recollections of a Grateful Student... 

Jannik Bjerrum received a thorough training (both in his home laboratory and at the University of Copenhagen) in classical chemistry, including qualitative and quantitative analysis (1 ). 

There is no doubt that Jannik Bjerrum obtained much inspiration from the kinetic and equilibrium studies of his father Niels Bjerrum (1879-1958), the physical chemist (6) best known for his work on chromium(III) complexes. Jannik obtained a comparable success, studying octahedral cobalt(III) conplexes of the N and NgO type (later extended to N O but not beyond S.M.Jj rgensen s type N-O prepared via [(0 NO)2Co(NH2)2] crystals). Jannik s great innovation of using activated charcoal as a catalyst for cobalt (III) equilibria also showed its intrinsic limitations by inducing... 

---