Coordination complexes as polyesterification catalysts

In a process for the manufacture of solid fiber-forming polyesters or copolyesters of dicarboxylic acid compounds and aliphatic glycols in the presence of catalysts, the improvement which comprises using as a polyesterification catalyst a coordination complex of (A) and (B), wherein:

• (A) is a metal alkoxy halide selected from the group consisting of
• M(OR).sub.a x.sub.b
• wherein M is at least one of titanium, zinc, germanium, tin, lead, antimony and;
• R is alkyl, aryl, alkylaryl, arylalkyl, haloalkyl having from 1 to 20 carbon atoms;
• a and b are integers having a value of from 1 to 3;
• the sum of (a+b) is equal to or less than the integer 4;
• x is at least one of F, Cl, Br or I;
• with the proviso that when M is antimony a is an integer having a value of from 1 to 4 and the sum (a+b) is equal to or less than 5;
• (B) is a silicon compound selected from the group consisting of:
• ##STR6## wherein W is CH.sub.2 .dbd.CX-- or ##STR7## X is hydrogen or methyl and is methyl only when m is one;
• R* is alkyl or haloalkyl having from 1 to 4 carbon atoms;
• R** is is methyl, ethyl, butyl, acetoxy, methoxy, ethoxy or butoxy;
• R is methyl, ethyl, butyl, methoxy, ethoxy, butoxy, or trimethylsiloxy;
• R' is methyl, methoxy, ethoxy, butoxy or trimethylsiloxy;
• R" is methoxy, ethoxy, butoxy, trimethylsiloxy or vinyldimethylsiloxy;
• R'" is methyl, ethyl, butyl or trimethylsilyl;
• Me is methyl;
• Z is methyl or W;
• Q is an NCCH.sub.2 --, NH.sub.2 CH.sub.2 NHCH.sub.2 --, NC--HS-- or HSCH.sub.2 CH.sub.2 S-- group;
• n is an integer having a value of from 2 to 5;
• m is an integer having a value of zero or one;
• x is an integer having a value of from 1 to 100;
• and
• y is an integer having a value of from 1 to 100;
• wherein the mole ratio of A:B in said coordination complex is from 2:1 to 1:10.