Diorganotin dihydrides

The diorganotin dihydrides react with catalysts based on the metallocenes of titanium, zirconium, or hafnium459 162 to give oligo- and polystannanes. 

The condensation of diorganotin dihydrides with diorganotin diamides is another route to cyclic polystannanes. This method is especially useful for the high-yield synthesis of the dimethyl derivative (Me2Sn)g [eqn (10.5)], which cannot be obtained by the dehydrocoupling process. 

SCHEME 16. Catalytic dehydrogenative coupling of diorganotin dihydrides... 

An early example for the direct coupling of a tin reagent to Amberlite XE 305, a macroporous polystyrene, was reported by Crosby and coworkers157. The synthetic route is shown in Scheme 35. Reaction of the polymer-supported diorganotin dihydride 70 with iodooctane to give octane indicated a minimum content of 2 mmol tin hydride per gram of the polymer. 

SCHEME 35. Synthesis of a polymer-supported diorganotin dihydride starting from Amberlite XE 305... 

The synthesis of tristannanes and linear tetrastannanes can be achieved in a straightforward manner by employing the hydrostannolysis reaction and diorganotin dihydrides (26) and 1,1,2,2-tetraorganodistannanes (9) according to Eq. (8) 49). As shown, this methodology can be used to... 

Borane is an effective reducing agent for organotin alkoxides and amides,11 and this has been exploited in the preparation of diorganotin dihydrides from the dioxastan-nolanes which can readily be obtained by azeotropic dehydration of a mixture of diorganotin oxide and 1,2-diol (e.g. equation 15-9).12... 

The hydrides R2SnHX (X = e.g. halide, carboxylate, sulphonate, alkoxyl) can be formed by the comproportionation between diorganotin dihydrides, R2SnH2, and the compounds R2SnX2. 

The availability of diorganotin dihydrides from the reduction of the corresponding di-oxastannolanes12 renders alkylation of a lithium tin hydride an attractive route to other organotin hydrides with mixed organic groups, R2R SnH.35-36... 

The diorganotin dihydrides R2SnH2 can be monolithiated at -50 °C to give the compounds R2SnHLi that are stable at low temperature but decompose at room temperature to give R3SnH and (R2Sn) . 

In an interesting extension of the above reactions, diorganotin dihydrides have been treated with amines to obtain cyclic polytin compounds 159,188, 192, 194a, 236, 236b, 236c). In one reported case 18S) a 94% yield of octadecaethylcyclononatin was obtained from diethyltin dihydride and a pyridine-diethyltin dichloride complex. It is apparently also possible to obtain straight-chain products with suitable reagents. 

A potentially quite useful synthetic method was recently reported by Sawyer and Kuivila 240-242), who treated diorganotin dihydrides with carboxylic acids to obtain functionally substituted ditin compounds. Thus, the reaction of dibutyltin dihydride with acetic acid leads to 1,2-diacetoxy-tetra-n-butylditin in 65% yield. 

I Reaction of diorganotin dihydride with bis(tributyltin)sulfide,... 

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