A Friendship over 35 Years

Abstract

This article describes the memoirs and history of correspondence of two outstanding chemists, R. Hoffman and A.A.Pasynskii. A number of discussions related to isoloble principle and the theory of molecular orbitals were considered.

The older readers will know the special bond I have had with Russian chemists. It stemmed from a year at MGU (actually in the Physics Faculty) in 1960–161. In the years that followed, I came as often as I could to the Soviet Union, and lectured widely. In part this was because I understood from my stay in the USSR how important this window on the world that lectures (and journals) formed for Soviet scientists. In part it was because I found scientists in Russia were more interesting people than scientists in the West. If you are wondering why I would imagine that, think about the choice facing an intelligent 19-year-old in Soviet times as he or she chooses between science and the humanities, between chemistry and philosophy or history, as his life’s work. The astute young person would choose science—there he or she would not have to shape their opinions to the party line, and could read roughly the same journals as their colleagues in the West. But the future scientist could hold on to his passions—in music, art, literature—in his or her private world. As a result, he often became a more interesting human being.

Also, as I switched my applied molecular orbital theory from thinking about organic molecules to organometallic and inorganic ones, there arose a special resonance between my theory and the good synthetic and structural work in Russia, especially at the Nesmeyanov Institute of Organoelement Compounds, and the Kurnakov Institute of General and Inorganic Chemistry.

So in 1983 there began a correspondence between me and Aleksandr Anatolyevich, which ended only with his leaving us in 2018. It began with Aleksandr sending to me the structures of the most recent clusters he had made, structures expertly determined by the Struchkov group. Here, poorly reproduced in Fig. 1, is one of the drawings he sent [1].

Fig. 1.

The structure of a Cr₂Fe cluster [1] sent in 1984 by A.A. Pasynskii to R. Hoffmann.

I sometimes made comments about bonding questions in the cornucopia of compounds his group synthesized [2]. Here (Fig. 2) are the first two pages of a letter I wrote to Aleksandr in 1985.

Fig. 2.

Two pages from a 1985 letter from R. Hoffmann to A.A. Pasynskii.

Note I wrote by hand, as I usually do, and in time Aleksandr Anatolyevich replied similarly. And here (Fig. 3) is the first page from a 1989 letter from him, so you can gauge the warmth of the bond between us.

Fig. 3.

First page of a 1989 letter from A.A. Pasynskii to R. Hoffmann.

And almost twenty years later, close to the end of his life, Aleksandr Anatolyevich wrote these verses for an Institute celebration (Fig. 4), connecting us again. I wish I had been there.

Fig. 4.

Some verses by A.A. Pasynskii, for an Institute celebration, dedicated to Roald Hoffmann.

Aleksandr Anatolyevich Pasynskii was a great inorganic and organometallic chemist, with a synthetic “green thumb. He was always asking questions of nature, and trying to understand. No chemical complexity stood in his way. His warmth and sincerity endeared him to me, and to others as well. We remember him.